Physiology of Nervous System PDF

BY DR. MOHAMED G. SHALAN 2021-2022 **CHAPTER 1** 1. Sensation - NS gathers information from both inside and outside the body (Sensory changes/events). Such changes are known as stimuli and the cells that monitor them are receptors. 2. Integration - Transmits info...

BY DR. MOHAMED G. SHALAN 2021-2022 **CHAPTER 1** 1. Sensation - NS gathers information from both inside and outside the body (Sensory changes/events). Such changes are known as stimuli and the cells that monitor them are receptors. 2. Integration - Transmits information to the processing areas of the brain and spine. - Interpretation of sensory information to determine the appropriate response. - Decide the needed reaction. 3. Reaction Motor output. 4. It controls and coordinates all essential functions of the body including all other body systems allowing the body to maintain homeostasis. 5. **The nervous system detects** and responds to changes inside and outside the body, together with the endocrine system; it controls important body functions and maintains homeostasis, with difference between speed of response to stimulation where the endocrine response is slow and takes a long time , the response by the nervous system is rapid. 1. **The Central Nervous System** : which consists of **the brain , the spinal cord** with **the meninges** and **the cerebrospinal fluid** surrounding them. 2. **The Peripheral Nervous System**: which consists of **the peripheral nerves.** -- -- -- --  1. Sensory (afferent) division - Nerve fibers that bring messages to the central nervous system 2. Motor (efferent) division - Nerve fibers that carry impulses *away from* the central nervous system - Two subdivisions 1. Somatic nervous system = voluntary 2. Autonomic nervous system = involuntary [The central nervous system:] ========================================= 1. **The Brain**: **[Site]**: Inside the skull **[Function]** : It plays a central role in the control of most body functions including awareness , movements , sensations , thoughts , speech and memory. The Spinal Cord: ================ **[Site:]** Runs through the spinal canal of the vertebral column and is connected to a part of the brain called the brain stem. **[Function]**: It carries signals back and forth between the brain and the peripheral nerves. 3. **The Cerebrospinal Fluid:** It surrounds the brain and the spinal cord and also circulates within cavities called the ventricles of the central nervous system. 4. **The Meninges:** They are three layers or membranes covering the brain and the spinal cord they are arranged from outside to inside as follows : 1. **The Dura Matter** 2. **The Arachnoid Matter** 3. **The Pia Matter.** **N.B.-**The cerebrospinal fluid circulates between the pia and arachnoid matters -The dura matter is the thick outer layer for protection of the brain. The human body contains billions of neurons Each neuron consists of **a body** and **an axon** The axons are coated by a fatty white material called myelin which allow nerves to communicate quickly.  1. **Irritability**: Is the ability of the neuron to initiate nerve impulses in response to stimuli from: 2. **Conductivity**: Is the ability to transmit an impulse. **N.B**. : the responses are initiated as electrical and are transmitted from neuron to the next as chemical impulses. - Cell body - Nucleus - Large nucleolus - Extensions outside the cell body - Dendrites -- conduct impulses toward the cell body - Axons -- conduct impulses away from the cell body (only 1!) - Axons end in axonal terminals - Axonal terminals contain vesicles with neurotransmitters - Axonal terminals are separated from the next neuron by a gap - Synaptic cleft -- gap between adjacent neurons - Synapse -- junction between nerves  - Astrocytes - Abundant, star-shaped cells - Brace neurons - Form barrier between capillaries and neurons - Control the chemical environment of - Microglia (CNS) - Spider-like phagocytes - Dispose of debris - Ependymal cells (CNS) - Line cavities of the brain and spinal cord - Circulate cerebrospinal fluid  - Oligodendrocytes (CNS) - Produce myelin sheath around nerve fibers in the central nervous system - Neuroglia divide. - Neurons do not. - Most brain tumors are ―gliomas.‖ - Most brain tumors involve the neuroglia cells, not the neurons. Consider the role of cell division in cancer! - Satellite cells - Protect neuron cell bodies - Schwann cells - Form myelin sheath in the peripheral nervous system  - Schwann cells -- produce myelin sheaths in jelly-roll like fashion - Nodes of Ranvier -- gaps in myelin sheath along the axon - Most are found in the central nervous system - Gray matter -- cell bodies and unmylenated fibers - Nuclei -- clusters of cell bodies within the white matter of the central nervous system - Ganglia -- collections of cell bodies outside the central nervous system  Functional Classification of Neurons: - Sensory (afferent) neurons - Carry impulses from the sensory receptors - Cutaneous sense organs - Proprioceptors -- detect stretch or tension - Motor (efferent) neurons - Carry impulses from the central nervous system - Interneurons (association neurons) - Found in neural pathways in the central nervous system - Connect sensory and motor neurons Structural Classification of Neurons - Multipolar neurons -- many extensions from the cell body.  - Bipolar neurons -- one axon and one dendrite - Unipolar neurons -- have a short single process leaving the cell body  - The plasma membrane at rest is polarized - When an stimuli affects sensory neuron. - Fewer positive ions are inside the cell than outside the cell - Starting a Nerve Impulse: - Depolarization -- a stimulus depolarizes the neuron's membrane - A deploarized membrane allows sodium (Na^+^) to flow inside the membrane - The exchange of ions initiates an action potential in the neuron - The Action Potential - If the action potential (nerve impulse) starts, it is propagated over the entire axon - Potassium ions rush out of the neuron after sodium ions rush in, which repolarizes the membrane - The sodium-potassium pump restores the original configuration - This action requires ATP - Nerve Impulse Propagation: - The impulse continues to move toward the cell body - Impulses travel faster when fibers have a myelin sheath - Continuation of the Nerve Impulse between Neurons - Impulses are able to cross the synapse to another nerve - Neurotransmitter is released from a nerve's axon terminal - The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter - An action potential is started in the dendrite - **How Neurons Communicate at Synapses**  - Some of the presynaptic inputs are excitatory. - Others are inhibitory to the post -synaptic neurons.. - synaptic cleft contain ECF. - The presynaptic neuron contains vesicles 1. Impulse arrives at the axon terminus causing opening of Ca+2 channels and allows Ca+2 to enter the axon. The calcium ions are in the extracellular fluid, pumped there much like sodium is pumped. Calcium is just an intermediate in both neuromuscular and synaptic transmission. 2. Ca+2 causes vesicles containing neurotransmitter to release the chemical into the synapse by exocytosis across the pre-synaptic membrane. 3. The neurotransmitter binds to the post-synaptic receptors. These receptors are linked to chemically gated ion channels and these channels may open or close as a result of binding to the receptors 4. The neurotransmitter is broken down or removed from the synapse in order for the receptors to receive the next stimulus. As we learned there are enzymes for some neurotransmitters such as the Ach-E which breaks down acetylcholine. Monoamine oxidase (MAO) is an enzyme which breaks down the catecholamines (epinephrine, nor-epinephrine, dopamine) and norepinephrine (which is an important autonomic neurotransmitter) is removed by the axon as well in a process known as reuptake. Other transmitters may just diffuse away. 1. Sub-threshold stimuli result in small local potentials (graded potentials) which must add together (summation) to produce an action potential. 2. A variety neurotransmitters can be involved with varying effects. 3. Neurotransmitters can be excitatory or inhibitory. The result might be to turn off the next neuron rather than to produce an action potential.  1. **One way conduction:-** - At a synapse impulses always pass from the pre- to the postsynaptic neuron, and never in the reverse direction. 2. Synaptic Fatigue - When the presynaptic neuron is repetitively stimulated at a rapid rate → exhaustion of neurotransmitter stores in synaptic knobs. - A protective mechanism e.g. Cessation of an epileptic fit. 3. **Synaptic delay** - The minimum time required for transmission across one synapse (0.5 ms). 4. Hypoxia - Synaptic transmission depends on adequate oxygenation. - If the blood supply to the brain stops → unconscious (5 seconds). - Definition: Difference in voltage of electrical charge between inside &outside the cell membrane - Is the potential difference in which inside cell negative relative to out side of the cell at rest -measure in mv. - RMP:- it is found almost in all cells. - RMP in neuron about -70 mv - RMP in skeletal muscle about -90 mv -Na^+^ permeability increases; membrane potential reverses -Na^+^ gates are opened; this lead to Na^+^ influx -Threshold -- a critical level of depolarization stage (-70 to -55 mV) -At threshold, depolarization becomes self-generating.  - Return cell to resting state - This due to close of Na channels and opening voltage K channels - Potassium gates remain open, causing an excessive efflux of K^+^ - This efflux causes hyper polarization of the membrane (undershoot) - **Definition**: It is sudden reversal in the membrane polarity, due to stimulus. - **Threshold**: It is the level at which AP develops and it changes RMP from -70mv to -55mv. - Stages of AP: ============= » Depolarization stage. » Repolarization stage.  IMPORTANCE OF AP: 1. Transmission of impulses along nerve fibers. 2. Contraction of muscles. 3. Reales of chemical transmitters in synapses. 4.Activation or inhibition of glandular secretion. The Reflex Arc - Reflex -- rapid, predictable, and involves both voluntary and - Reflex arc -- direct route from a sensory neuron, to an interneuron, to an effector  - Autonomic reflexes - Smooth muscle regulation - Heart and blood pressure regulation - Regulation of glands - Digestive system regulation - Somatic reflexes - Activation of skeletal muscles Important definitions: - Dendrite -- receive stimulus and carries it (impulse) toward the cell body - Axon -- fiber which carries impulses away from cell body - Schwann Cells- cells which produce myelin or fat layer in the Peripheral Nervous System - Myelin sheath -- dense lipid layer which insulates the axon -- makes the axon look gray - Node of Ranvier -- gaps or nodes in the myelin sheath - Impulses travel from dendrite to cell body to axon Three types of Neurons - Sensory neurons -- bring messages to CNS - Motor neurons - carry messages from CNS - Interneurons -- between sensory & motor neurons in the CNS Impulses - A stimulus is a change in the environment with sufficient strength to initiate a response. - Excitability is the ability of a neuron to respond to the stimulus and convert it into a nerve impulse - All of Nothing Rule -- The stimulus is either strong enough to start and impulse or nothing happens - Impulses are always the same strength along a given neuron and they are self-propagation -- once it starts it continues to the end of the neuron in only one direction- from dendrite to cell body to axon - The nerve impulse causes a movement of ions across the cell membrane of the nerve cell. - It is junction between neurons which uses neurotransmitters to start the impulse in the second neuron or an effector (muscle or gland) - The synapse insures one-way transmission of impulses A. Receptor - reacts to a stimulus B. Afferent pathway (sensory neuron) - conducts impulses to the CNS C. Interneuron - consists of one or more synapses in the CNS (most are in the spine) D. Efferent pathway (motor neuron) conducts impulses from CNS to effector. E. Effector - muscle fibers (as in the Hamstring muscle) or glands responds by contracting or secreting a product. **CHAPTER 2** Sensation Sensory receptors:- specialized neurons or epithelial cells or sensory nerve ending that respond to specific or generalized stimuli from the internal or external environment of an organism. Receptors are transducers: (Transducer device which changes one form of energy to another form). Properties of receptors: 1. Adequate stimulus: Each types of receptor is sensitive to specific form of energy called its adequate stimulus 2. Adaptation. 3. Excitability: Stimulation of receptor result in receptor potential Types of sensations 1. General senses: Like pain, temperature, touch, pressure, vibration and proprioception. 2. Special senses: Like olfaction, vision, gustation, equilibrium, and hearing. First classification of receptors: - Teleceptors (Detect distant events e.g. visual receptor) - Exteroceptors (Immediate external environment -- touch receptor) - Interoceptors (Internal environment e.g. chemoreceptor) - Proprioceptors (Changes in position of the body ) - Nociceptors (Pain receptors -- detect all painfull stimuli arise due to injury or tissue damage) Second classification of receptors: 1. Mechanoreceptors: Sense physical deformation caused by stimuli such as pressure, stretch ,sound, touch. 50\_03HumanSkinReceptors-L.jpg 2. Chemoreceptors: Transmit information about the total solute concentration of a solution - Specific chemoreceptors respond to individual kinds of molecules - When bind , chemoreceptors becomes less or more permeable 3. Electromagnetic receptors: Detect electromagnetic energy such as light, electricity and magnetism 4. Photoreceptors: Detect light 5. Thermo-receptors: Respond to heat, cold, help to regulate body temperature by signaling both surface and body core temperature 6. Pain receptors: In human , pain receptor or nociceptors are a class of naked dendrites in the epidermis - They respond to excess heat, pressure or chemicals released from damaged or inflamed tissues. - Humans have 5 senses: touch, taste, smell, sight, and hearing. The senses are based on receptor cells or groups of receptor cells called sense organs. 1. Gustation 2. Smell  3. Vision: - Visual Receptors: Its function is detecting and interpreting visual stimuli by converting light energy to nerve impulses and transmitting them to the brain. - Rods used in dim light: rhodopsin - Cones used for color vision and sharpest vision 4. Touch:  5. Hearing - Vision -- Eye - Hearing -- Ear - Taste -- Taste receptors (new) - Smell -- Olfactory system - Skin (Touch) -- Hot, cold, pressure, pain - It composed of three layers -- - 1\. Outer layer consists of sclera and cornea - 2\. Middle layer consists of choroid, ciliary body and iris - 3\. Inner layer consists of retina - The iris in humans is the colored (typically brown, blue, or green) area, with the [[pupil]](https://en.wikipedia.org/wiki/Pupil) (the circular black spot) in its center, and surrounded by the white [[sclera]](https://en.wikipedia.org/wiki/Sclera) which is covered with cornea which is completely transparent. that can not be seen except the shine it gives to the eye.  Functions of the major parts of the eye: - Cornea - the clear, dome-shaped part of the sclera covering the front of the eye through which light enters the eye - Anterior Chamber -- a small chamber between the cornea and the pupil - Aqueous Humor - the clear fluid that fills that anterior chamber of the eye and helps to maintain the shape of the cornea providing most of the nutrients for the lens and the cornea and involved in waste management in the front of the eye - Choroid Layer - middle layer of the eye containing may blood vessels - Ciliary Body - the ciliary body is a circular band of muscle that is connected and sits immediately behind the iris- produces aqueous humor, changes shape of lens for focusing, and - Iris - the pigmented front portion of the choroid layer and contains the blood vessels - it determines the eye color and it controls the amount of light that enters the eye by changing the size of the pupil (an albino only has the blood vessels -- not pigment so it appears red or pink because of the blood vessels) - Lens - a crystalline structure located just behind the iris - it focuses light onto the retina - Pupil - the opening in the center of the iris- it changes size as the amount of light changes (the more light, the smaller the hole) - Vitreous - a thick, transparent liquid that fills the center of the eye - it is mostly water and gives the eye its form and shape (also called the vitreous humor) - Retina - sensory tissue that lines the back of the eye. It contains millions of photoreceptors (rods for black & white and cones for color ) that convert light rays into electrical impulses that are relayed to the brain via the optic nerve - Optic nerve - the nerve that transmits electrical impulses from the retina to the brain Common eye defects include -- - myopia or nearsightedness where the eyeball is too long or the cornea is too steep; - hyperopia or far sightedness where the eyeball is short or lens cannot become round enough: cataracts where the lens becomes fogged; presbyopia where the muscles controlling the bulging of the lens become weak as we age; nyctalopia or night blindness where vision is impaired in dim light and in the dark due to pigment rhodospin in the rods not functioning properly - the cornea and the lens help to produce the image on the retina images formed by the lens are upside down and backwards when they reach the retina two types of receptors on the retina Rods -- 125 million on a single retina -- extremely sensitive to all wavelengths of visible light but do not distinguish different color -- in dim light only rods are activated where one can see objects but not as sharp images and are not able to distinguish their color -- most dense in peripheral view -- nighttime vision Rods have a pigment called rhodopsin. - As amount of light increases, the cones -- 7 million on a single retina -- mainly in central view are stimulated and the color becomes clear -- daytime vision There are three types of cones which distinguish the three colors -- blue, red, green Fovea -- point of central focus -- great density of cones - center of the eye\'s sharpest vision and the location of most color perception - the layers of the retina spread aside to let light fall directly on the cones Light stimulates rods and cones and sends impulse via optic nerve to brain areas for vision The Optic Nerve exits the eye just off center near the Fovea - the Optic Nerve exits is referred to as the Blind Spot due to the lack of the receptors in this area The two Optic Nerves come together at the Optic Chiasm located just under the hypothalamus - a crucial part of vision and perception must happen - cross-over of information from the right eye crosses over to the left side and visa versa happens here at the Optic Chiasm.  Information from each eye must be processed in both halves of the brain Information leaves the chiasm via the optic tract. Reorganized optic tract leaves the Optic Chiasm and passes onto the lateral geniculate nucleus At the lateral geniculate nuclei the information is separated, organized, and relayed to different areas of the visual cortex The different zones of the visual cortex process the different aspects of vision and information, taken from both visual fields, is processed and an image is perceived. - Outer Ear & ear canal -- brings sound into eardrum. - Eardrum -- vibrates to amplify sound & separates middle and inner ear Middle ear has 3 small bones or Ossicles = Hammer, anvil, stirrup (Malleus, Incus, Stapes). stapes -- amplify sound (small bones) which vibrate sound. - Eustachian tube -- connects middle ear to throat and equalizes pressure on eardrum. Cochlea -- in inner ear -- has receptors for sound & sends signals to brain via Auditory Nerve. Process of hearing: - Sound waves enter the outer ear and travel through the ear canal to the middle ear. - The ear canal channels the waves to the eardrum, a thin, sensitive membrane stretched tightly over the entrance to the middle ear. - The waves cause the eardrum to vibrate. - It passes these vibrations on to the hammer, one of three tiny bones in the ear. The hammer vibrating causes the anvil, the small bone touching the hammer, to vibrate. The anvil passes these vibrations to the stirrup, another small bone which touches the anvil. From the stirrup, the vibrations pass into the inner ear. \*The stirrup touches a liquid filled sack and the vibrations travel into the cochlea, which is shaped like a shell. Inside the cochlea, a vestibular system formed by three semicircular canals that are approximately at right angles to each other and which are responsible for the sense of balance and spatial orientation. It has chambers filled with a viscous fluid and small particles (otoliths) containing calcium carbonate. The movement of these particles over small hair cells in the inner ear sends signals to the brain that are interpreted as motion and acceleration. The brain processes the information from the ear and lets us distinguish between different types of sounds.  Taste and Smell -- Chemical Receptors Taste buds The mouth contains around 10,000 taste buds, most of which are located on and around the tiny bumps on the tongue. Every taste bud detects five primary tastes: o Sour o Sweet o Bitter o Salty o Umami - salts of certain acids (for example monosodium glutamate or MSG) Each of the taste buds contains 50-100 specialized receptor cells. Sticking out of every single one of these receptor cells is a tiny taste hair that checks out the food chemicals in your saliva. When these taste hairs are stimulated, they send nerve impulses to your brain. Each taste hair responds best to one of the five basic tastes. - Humans able to detect thousands of different smells - Olfactory receptors occupy a stamp-sized area in the roof of the nasal cavity, the hollow space inside the nose - Tiny hairs, made of nerve fibers, dangle from all your olfactory receptors. They are covered with a layer of mucus. - If a smell, formed by chemicals in the air, dissolves in this mucus, the hairs absorb it and excite your olfactory receptors. - A few molecules are enough to activate these extremely sensitive receptors.  Skin receptors: - Your skin and deeper tissues contain millions of sensory receptors. Most of your touch receptors sit close to your skin\'s surface. - Light touch Meissner\'s corpuscles are enclosed in a capsule of connective tissue They react to light touch and are located in the skin of your palms, soles, lips, eyelids, external genitals and nipples these areas of your body are particularly sensitive. Heavy pressure - Paccinian corpuscules sense pressure and vibration changes deep in your skin. - Every square centimeter of your skin contains around 14 pressure receptors - skin receptors register pain pain receptors are the most numerous - each square centimeter of your skin contains around 200 pain receptors - skin receptors register warmth and cold - each square centimeter of your skin contains 6 receptors for cold and 1 receptor for warmth - Cold receptors start to perceive cold sensations when the surface of the skin drops below 95 º F. They are most stimulated when the surface of the skin is at 77 º F and are no longer stimulated when the surface of the skin drops below 41 º F. This is why your feet or hands start to go numb when they are submerged in icy water for a long period of time. - Hot receptors start to perceive hot sensations when the surface of the skin rises above 86 º F and are most stimulated at 113 º F. Beyond 113 - thermoreceptors are found all over the body, but cold receptors are found in greater density than heat receptors -- most of the time of our environment is colder than our body temperature - The highest concentration of thermoreceptors can be found in the face and ears so your nose and ears always get colder faster than the rest of your body on a chilly winter day **Chapter 3** - CNS develops from the embryonic neural tube - The neural tube becomes the brain and spinal cord - The opening of the neural tube becomes the ventricles - Four chambers within the brain - Filled with cerebrospinal fluid  - **Diencephalon** - **Brain stem** - **Midbrain** - **Pons** - **Medulla oblongata** - **Cerebellum** - **Brain stem**  The corpus callosum is a large white matter tract that connects the two [[hemispheres of the brain]](https://www.kenhub.com/en/library/anatomy/topography-of-the-cerebral-hemispheres) Cerebral Hemispheres (Cerebrum) - Paired (left and right) superior parts of the brain - Include more than half of the brain mass Cerebrum - The surface is made of ridges (gyri) and grooves (sulci) Lobes of the Cerebrum - Fissures (deep grooves) divide the cerebrum into lobes - Surface lobes of the cerebrum - Frontal lobe - Parietal lobe - Occipital lobe - Temporal lobe Specialized Areas of the Cerebrum - Somatic sensory area -- receives impulses from the body's sensory receptors  - Primary motor area -- sends impulses to skeletal muscles - Broca's area -- involved in our ability to speak Sensory and Motor Areas of the Cerebral Cortex: Specialized Areas of the Cerebrum - Cerebral areas involved in special senses - Gustatory area (taste) - Visual area - Auditory area - Olfactory area  Interpretation areas of the cerebrum - Speech/language region - Language comprehension region - General interpretation area Motor areas of the cerebrum For movement of head, arms, elbow, wrist, hands, fingers, thumb, neck face, lips, jaws, tongue, pharynx, esophagus, small and large intestine, Hip, trunk and Legs. Layers of the Cerebrum - Gray matter - Outer layer - Composed mostly of neuron cell bodies  - White matter - Fiber tracts inside the gray matter - Example: corpus callosum connects hemispheres - Basal nuclei -- internal islands of gray matter - Regulates voluntary motor activities by modifying info sent to the motor cortex - Problems = ie unable to control muscles, spastic, jerky - Involved in Huntington's and Parkinson's Disease Diencephalon - Sits on top of the brain stem - Enclosed by the cerebral heispheres - Made of three parts - Thalamus - Hypothalamus - Epithalamus Thalamus - Surrounds the third ventricle - The relay station for sensory impulses - Transfers impulses to the correct part of the cortex for localization and interpretation Hypothalamus - Under the thalamus - Important autonomic nervous system center - Helps regulate body temperature - Controls water balance - Regulates metabolism - Neural control for pituitary gland for feed back control of hormonal secretion (Hormonal control) through its releasing factors or releasing hormones. - An important part of the limbic system (emotions) - The pituitary gland is attached to the hypothalamus Epithalamus - Forms the roof of the third ventricle - Houses the pineal body (an endocrine gland) - Includes the choroid plexus -- forms cerebrospinal fluid Brain Stem - Attaches to the spinal cord - Parts of the brain stem - Midbrain - Pons - Medulla oblongata  - Mostly composed of tracts of nerve fibers - Reflex centers for vision and hearing Pons - Cerebral aquaduct -- 3^rd^-4^th^ ventricles - The bulging center part of the brain stem - Mostly composed of fiber tracts - Includes nuclei involved in the control of breathing Medulla Oblongata - The lowest part of the brain stem - Merges into the spinal cord - Includes important fiber tracts - Contains important control centers - Heart rate control - Blood pressure regulation - Breathing - Swallowing - Vomiting Cerebellum - Two hemispheres with convoluted surfaces - Provides involuntary coordination of body movements - Important for body balance Protection of the Central Nervous System - Scalp and skin - Skull and vertebral column - Meninges - Cerebrospinal fluid - Blood brain barrier  Meninges - Dura mater - Double-layered external covering - Periosteum -- attached to surface of the skull - Meningeal layer -- outer covering of the brain - Folds inward in several areas - Arachnoid layer - Middle layer - Web-like - Pia mater - Internal layer - Clings to the surface of the brain Cerebrospinal Fluid - Similar to blood plasma composition - Formed by the choroid plexus - Forms a watery cushion to protect the brain - Circulated in arachnoid space, ventricles, and central canal of the spinal cord Ventricles and Location of the Cerebrospinal Fluid  Blood Brain Barrier - Includes the least permeable capillaries of the body - Excludes many potentially harmful substances - Useless against some substances - Fats and fat soluble molecules - Respiratory gases - Alcohol - Nicotine - Anesthesia Cerebrum Lobes of the brain +-----------------------+-----------------------+-----------------------+ | | | 1. 2. | +-----------------------+-----------------------+-----------------------+ +-----------------------+-----------------------+-----------------------+ | | | 1. | | | | | | | | | | | | | | | | 2. | +-----------------------+-----------------------+-----------------------+ | | | | +-----------------------+-----------------------+-----------------------+ | | | | +-----------------------+-----------------------+-----------------------+ | | | | +-----------------------+-----------------------+-----------------------+ | | | | +-----------------------+-----------------------+-----------------------+ | | | | +-----------------------+-----------------------+-----------------------+ | | | | +-----------------------+-----------------------+-----------------------+ | | | | +-----------------------+-----------------------+-----------------------+ -- -- -- -- -- -- The Base Of The Brain: ====================== The structure ---------------------- -- -- **1-The cerebellum** It is a compact structure that connects the brain with the spinal cord and in which multiple pathways traverse from the brain to the spinal cord and vice versa. -- -- -- -- -- -- +-----------------------+-----------------------+-----------------------+ | | | 1. | | | | | | | | | | | | | | | | 2. | +=======================+=======================+=======================+ | | | 1. 2. | +-----------------------+-----------------------+-----------------------+ The Limbic System and Higher Mental Functions The Limbic System is a complex set of structures found just beneath the cerebrum and on both sides of the thalamus. It combines higher mental functions, and primitive emotion, into one system. It is often referred to as the emotional nervous system. It is not only responsible for our emotional lives, but also our higher mental functions, such as learning and formation of memories. The Limbic system explains why some things seem so pleasurable to us, such as eating and why some medical conditions are caused by mental stress, such as high blood pressure. There are two significant structures within the limbic system and several smaller structures that are important as well. Structures of limbic system 1. The Hippocampus 2. The Amygdala 3. The Thalamus 4. The Hypothalamus 5. The Fornix 6. The Cingulate Gyrus +-----------------+-----------------+-----------------+-----------------+ | | | | | +-----------------+-----------------+-----------------+-----------------+ | 1. | | 1. 2. | | +-----------------+-----------------+-----------------+-----------------+ | | | 1. | | | | | | | | | | | | | | | | | | | | 2. | | +-----------------+-----------------+-----------------+-----------------+ | | | | | +-----------------+-----------------+-----------------+-----------------+ -- -- -- -- -- -- 1. **The amygdala** (in the temporal lobe) responsible for feelings. the amygdala play an important role on the mediation and control of such activities and feelings as love, friendship, affection, and expression of mood. The amygdala is the center for identification of danger and is fundamental for self preservation. The amygdala is the nucleus responsible for fear. - 2-The Fornix - A small structure that is an important connecting pathway for the limbic system - 3\. The Cingulate Gyrus - It coordinates smells and sights, with pleasant memories of previous emotions. The region participates in the emotional reaction to pain and in the regulation of aggressive behavior. **Chapter 4** The peripheral nervous system It is a way of communication from the central nervous system to the rest of the body by nerve impulses that regulate the functions of the human body. It can be subdivided into the somatic and autonomic systems. Somatic Nervous System (voluntary) - Relays information from skin, sense organs & skeletal - muscles to CNS - Brings responses back to skeletal muscles for voluntary - responses Autonomic Nervous System (involuntary) - Regulates bodies involuntary responses - Relays information to internal organs Two divisions - \- Emergency response - \- Fight or flight The peripheral nervous system includes: - Cranial nerves 12 pair, attached to undersurface of brain - Spinal nerves 31 pair, attached to spinal cord The twelve cranial nerves are - I Olfactory Nerve for smell - II Optic Nerve for vision - III Oculomotor for looking around - IV Trochlear for moving eye - V Trigeminal for feeling touch on face - VI Abducens to move eye muscles - VII Facial to smile, wink, and help us taste - VIII Vestibulocochlear to help with balance, - equilibrium, and hearing - IX Glossopharengeal for swallowing and gagging - X Vagus for swallowing, talking, and parasympathetic actions of digestion - XI Cranial accessory for shrugging shoulders - XII Hypoglossal for movement of tongue. Peripheral nervous system: ========================== - The peripheral nervous system consists of all nerves outside the brain and spinal cord and also nerve fibers that exit the brainstem and spinal cord become part of the peripheral nervous system. - Cranial nerves exit from the brain stem and function as peripheral nervous system mediators of many functions including eye movements , facial strength ,sensations , hearing and taste. - The optic nerve is considered a cranial nerve but it is generally affected in a disease of the central nervous system known as multiple sclerosis and for this reason and other reasons it is represents an extension of the central nervous system as apparatus that controls vision.  Spinal Nerves Autonomic Nervous System - The involuntary branch of the nervous system - Consists of only motor nerves - Divided into two divisions - Sympathetic division - Parasympathetic division Comparison of Somatic and Autonomic Nervous Systems  Difference Between Sympathetic and Parasympathetic Neuron: -- -- -- -- -- -- Anatomy of the Autonomic Nervous System [Origin And Distribution Of ANS] ============================================ A - [Sympathetic] : Thoraco-lumber outflow. B - [Parasympathetic]: Cranial and Saccral  Autonomic Ganglia : It is the site of synapse (relay) between pre and Postganglionic neurons of autonomic nerves. It acts as distribution center. Thoraco-lumber outflow from 1st thoracic to the 3rd lumber segments. Distribution of Sympathetic Out Flow : 1. **- [Cervical Sympathetic]** : From T1 & T2 ( upper thoracic ). Postganglionic neurons pass to head and neck to supply eye, salivary glands, and skin. 2. **- [Cardio - Pulmonary division]** : originate from upper thoracic (T2,T3,T4). Postganglionic neurons pass to heart and lungs. 3. **- [Great Splanchic Nerve]** ( thoracic splanchic ): a Preganglionic neuron originate from T5 to T12, pass to abdominal viscera ( stomach , small intestine, liver , pancreas , kidney , gall bladder. and upper large intestine 4. **- [Lesser Splanchic nerve]** (lumber splanchic): originate from L1, L2, and L3. to supply pelvic organs ( rectum, urinary bladder , and sex organs ). THE PARASYMPATHATIC OUTFLOW =========================== A [ - Cranial Outflow :] ==================================== 1. -- [Occulomotor Nerve] ( III ): It innervate the Constrictor Pupille, and Ciliary muscle. 2. \- [Fascial Nerve] ( VII ) : innervate salivary glands, and also the lacrimal glands. 3. \- [Glossopharengeal Nerve] ( IX ) : supply parotid salivary glands. 4. \- [Vagus Nerve] ( X ) : carries parasympathetic fibers to all thoracic and abdominal organs. B [ - Sacral Outflow :] =================================== Preganglionic parasympathetic fibers (S2, S3, S4) form the pelvic nerve (nervie erigentes), relay in parasympathetic ganglia in the wall of pelvic organs e.g. sigmoid colon, rectum, urinary bladder, uterus, and sex organs. FUNCTIONS OF AUTONOMIC NERVOUS SYSTEM ===================================== General functions of sympathetic (Generalized Sympathetic Activation) It occurs in states of emotional excitement to face the environmental stress E.g. fight or flight reaction. The following reactions occur: 1. \- Increase heart rates and force of contraction 2. \- Generalized vasoconstriction, which lead to increase blood pressure. 3. \- Bronchodiltation to increase air flow. 4. \- Increases sweat secretion. 5. \- Pupillary dilatation. 6. \- Increase release of catecholamines from adrenal medulla. General Functions of Parasympathetic Its activity is mainly to build up and conserve of body energy stores during rest. It increases the secretion and motility of GIT, helps defecation and micturition. The spread of parasympathetic discharge is limited due to rapid destruction of acetylcholine, and the location of its ganglia near to the organs. Parasympathetic: ================ a - Contraction circular muscles of the pupil ( pupillary constrictor ) causing pupillary constriction ( Miosis ) b - Contraction of ciliary muscles ( lens becomes more spherical ),helps accommodation to near object e.g. during reading. c - Stimulate lacrimal secretion ( VD of BV ). -[Coetaneous structures:] ===================================== a - Vasoconstriction ( V.C. ) of skin blood vessels. b - Stimulate sweat secretion. c - Erection of hair. [Parasympathetic:] ============================== No effect - [ Salivary glands:] ================================= a - Trophic secretion , small in volume , viscus, rich in mucous. b - V.C. of blood vessels Parasympathetic: ================ a - Physiologic secretion, large in volume , watery. and rich in enzymes. - Heart; ======== a - Increase all the properties of the cardiac muscles (excitability, rythmisity, conductivity, and contractility). b - Increase activation of SA node. c - Increase heart rate. d - Increase systolic blood pressure. e - Increase cardiac output. [Parasympathetic:] ============================== Postganglionic fibers supply atrial and conductive system. a - Decrease heart rate ( vagal tone ) b - decrease all properties of cardiac muscle. - [ Blood Vessels:] =============================== B.V. with dual innervation: Vasoconstriction. [Blood vessels receiving single innervation:] a -Most of the body B.V. is normally held in a state of moderate vasoconstriction (sympathetic tone ) e.g. cutanous blood vessels. Decrease sympathetic tone produce vasodilatation ( V.D. ). b - Coronary blood vessels have more than one type of adrenoreceptors, stimulation of alpha -receptor produce v.c. , stimulation of beta -receptors produce VD, in man increased metabolism by sympathetic stimulation cause V.D. c - On skeletal muscles blood vessels: - sympathetic adrenergic stimulate α- receptors causing V.C. at rest. - sympathetic cholinergic produce V.D. upon expectation of an exercise. Parasympathetic: ================ Vasodilatation of blood vessels. - Lung: ======= Bronchoconstriction ( in animals ) - Gastro-Intestinal Tract ========================= **Sympathetic**: Generally it decrease secretion and motility of GIT A\) Stomach Sympathetic a - inhibit gastric secretion. b - decrease gastric motility c - contraction of pyloric sphincter Parasympathetic a - stimulate gastric secretion. b - increase gastric motility. c - contraction of the smooth muscles of the wall of stomach d - relaxation of pyloric sphincter, so helps evacuation of the stomach. e - V.D. of blood vessels B ) Intestine: ============== Sympathetic a - inhibit intestinal motility. b - decrease intestinal secretion c - V.C. of blood vessels. Parasympathetic a - increase peristaltic movement b - increase intestinal secretion c - V.D. of intestinal blood vessels. c ) Gall bladder: ================= Sympathetic a - relaxation of the wall and contraction of sphincter. Parasympathetic a - contraction of the wall b - relaxation of sphincter of Odii. 8. \- Urinary bladder: Sympathetic a - relaxation of the wall and contraction of the sphincter. Parasympathetic a - contraction of the wall b - relaxation of internal uretheral sphincter Helps micturation. [- Sex Organs] ========================== Sympathetic a - contraction of the smooth muscle of the male reproductive ducts leads to b - V.C. of pelvic blood vessels causing shrinking of sexual organs. Parasympathetic a - vasodilatation of the blood vessels of sexual organs causes erection. [CHEMICAL TRENSMISSION] =================================== The principal transmitters are acetylcholine ( AC ) and norepinephrine ( NE ). I. - [ ACETYLCHOLINE] (Cholinergic system) [Sites of release :] ==================================================================================== 1. \- All preganglionic neurons. 2. \- All autonomic ganglia. 3. \- All parasympathetic postganglionic neurons. 4. \- Sympathetic postganglionic neurons to sweat glands and vasodilators of blood vessels of skeletal muscles. 5. \- Adrenal medulla. 6. \- Neuromuscular junction. II. - [NOREPINEPHRINE] (Adrenergic system) ================================================== NE is present in granulated vesicles of nerve terminals present in most sympathetic postganglionic endings and some brain neurons. AUTONOMIC RECEPTORS =================== - Are stimulated by small dose of nicotine and blocked by large dose. - It is present in autonomic ganglia and neuromuscular junction. B - Muscarinic Recptors ======================= They are stimulated by muscarine and blocked by atropine. [Actions Of Acetylcholine ( Cholinergic actions )] A - Muscarinic actions: ====================================================================================== 7. \- Cardiac inhibition and decrease heart rate. 8. \- Pupillary constriction. 9. \- Contraction of ciliary muscles. 10. \- Stimulate salivary secretion. 11. \- Stimulate gastrointestinal secretion and motility 12. \- Contraction of urinary bladder and rectum. 13. \- Bronchoconstriction. B - Nicotinic action: ===================== 1. \- Stimulation of autonomic ganglia. 2. \- Stimulate adrenal medulla to secrete adrenaline and nor adrenaline. 3. \- Stimulate NM junction causing skeletal muscle contraction. Adrenergic receptors ==================== They respond to different catecholamines (Epinephrine, Norepinephrine, and Dopamine). Subtypes: ========= **Alpha 1** : present in vascular smooth muscle, pupillary radial muscles, pilomotor muscles, gut and bladder sphincters. Beta Receptors: =============== [Beta 1]: present in cardiac muscle. [Beta 2]: present in bronchial, gut, and bladder smooth muscles. Chapter 5 Diseases associated with nervous system - **In Multiple Scleroses (MS) the myelin sheath is destroyed.** - **The myelin sheath hardens to a tissue called the scleroses.** - **This is considered an autoimmune disease.**  Alzheimer's disease Alzheimer's disease is a type of dementia that affects a person's thinking, behaviour and ability to perform everyday tasks. Alzheimer's disease is associated with a build-up of certain proteins and chemicals in the brain, which leads to dementia symptoms that worsen over time. While Alzheimer's disease is more common in older Australians, it is not a normal part of ageing. There is no cure for Alzheimer's disease, but some medications and the learning of new behaviours can help relieve symptoms and improve quality of life. symptoms of Alzheimer's disease? Early on, Alzheimer's disease may be hard to notice. The first signs are usually memory loss and difficulty finding the right words for everyday things. However, many people have trouble with memory but don't have Alzheimer's --- so it's important to visit a doctor to work out the exact cause of memory problems. Other common symptoms of Alzheimer's disease include: - vagueness in daily conversation - lack of enthusiasm for activities you once enjoyed - taking longer to do regular tasks - forgetting well-known people or places - difficulty processing questions and instructions - a decline in social skills - unpredictable emotions Alzheimer's disease is sometimes classified into 3 stages, based on the severity of symptoms: - **Mild Alzheimer's disease**: early signs of dementia, no additional support is usually needed. - **Moderate Alzheimer's disease**: symptoms are difficult to cope with and support is likely to be required. - **Advanced Alzheimer's disease**: continuous care in all daily activities may be needed. - Causes Alzheimer's disease: - Several processes occur in Alzheimer's disease, including amyloid plaque deposits, neurofibrillary tangles and neuronal death. - **Amyloid plaques** are deposits *outside* the brain cells --- they prevent the brain from passing signals properly. - **Neurofibrillary tangles** are deposits *inside* the brain cells --- they kill the cells by blocking off food and energy, causing dementia that worsens over time. - **Neuronal death** causes shrinking in the outer layer of the brain (the cortex) which is vital to memory, language and judgement --- Alzheimer's disease is characterised by this shrinkage. - In most cases, scientists are still unsure of what triggers the formation of plaques, tangles and other chemical changes associated with sporadic Alzheimer\'s disease. Suspected causes include environmental factors, chemical imbalances or the body's own [[immune system]](https://www.healthdirect.gov.au/immune-system). - Alzheimer's disease tends to target the outer part of the brain first, which is associated with learning and short-term memory. As the disease progresses deeper into the brain, other functions are affected and symptoms get worse. - For people with familial Alzheimer's disease, mutations in 3 genes have been found to increase the production of amyloid plaques that damage the brain. There are other \'risk-factor genes\' that may increase a person\'s chance of getting Alzheimer's disease earlier in life. - How is Alzheimer's disease diagnosed? - Unfortunately, there is no single test that can confirm Alzheimer's disease. A diagnosis comes after careful assessment. This may involve: - \- a detailed medical history - \- a complete physical and neurological examination - \- tests to check intellectual function - \- a [[psychiatric]](https://www.healthdirect.gov.au/psychiatrists-and-psychiatry) assessment - \- neuropsychological tests - \- urine and [[blood tests]](https://www.healthdirect.gov.au/blood-tests-a-z) - medical imaging, such as an [[MRI scan]](https://www.healthdirect.gov.au/magnetic-resonance-imaging-mri) to assess shrinking of the brain - After eliminating other possible causes of symptoms (such as vascular dementia, nutritional deficiencies or depression), a clinical diagnosis of Alzheimer's can be made. - An early diagnosis allows your doctor to work out if there is another cause of your symptoms that may be treatable. If a diagnosis of Alzheimer's disease is most likely, you can start to discuss medical treatment and further assistance to help slow the degenerative process. - How is Alzheimer\'s disease treated? - Although there is no cure, certain treatments may improve symptoms for a time. Many people with Alzheimer's disease also learn ways to cope with their symptoms, and improve their quality of life. - Medications - A group of medicines called cholinergic drugs may temporarily improve cognitive symptoms of mild-to-moderate Alzheimer's disease. These work by increasing the level of a brain chemical called acetylcholine, which helps to restore communication between brain cells. - Other medications help to relieve behavioural symptoms such as [[sleeplessness]](https://www.healthdirect.gov.au/insomnia), agitation, [[anxiety]](https://www.healthdirect.gov.au/anxiety-related-disorders) and [[depression]](https://www.healthdirect.gov.au/depression). These treatments don't treat Alzheimer's disease directly but can help improve quality of life. - Lifestyle changes - Where possible, a person with Alzheimer's disease should try to maintain normal social contact with friends and family, [[exercise]](https://www.healthdirect.gov.au/physical-activity-guidelines-for-older-adults) [[regularly]](https://www.healthdirect.gov.au/physical-activity-guidelines-for-older-adults) and engage in activities that stimulate the brain. If you have any concerns about safety (for example, driving skills) see your doctor for advice. - Other interventions - If you care for someone with Alzheimer's disease, it may be helpful to make changes to their home environment to help them feel less disoriented in daily life. For example, you could add clear instructions on how to open doors, or install alert devices if the person is prone to getting lost. Check out [[Dementia Australia's help sheets]](https://www.dementia.org.au/resources/help-sheets) on creating a dementia-friendly environment. Bell's palsy is a sudden weakness or paralysis in one side of the face. It is caused by inflammation or damage to the facial nerve. It is usually temporary --- most people start to get better in 2 weeks and are fully recovered in 3 to 6 months. A few people don't recover fully and are left with some weakness or paralysis of the muscles in their face. - The main symptom is weakness or paralysis of one side of the face. - a drooping eyelid or difficulty closing one eye - difficulty smiling and making facial expressions - drooping of one side of the mouth - difficulty eating and drinking - drooling - pain or sensitivity around the affected area - [[a headache]](https://www.healthdirect.gov.au/headaches) - loss of taste - changes in the amount of tears or saliva  - causes Bell's palsy: - A viral infection is thought to be the main cause of Bell\'s palsy. - The infection inflames or puts pressure on the nerve that controls the facial muscles. It can be mild, or it can be severe. - Treatment of Bell's palsy: - To treat Bell\'s palsy, a doctor may prescribe oral steroids, or an antiviral medicine in the first few days of the onset of Bell's palsy, as this can improve the chance of a full recovery. - They may also prescribe lubricating eye drops, an eye ointment to protect the affected eye and they may recommend physiotherapy or face massage. - Motor neuron disease (MND) - Motor neuron disease (MND) is the name for a group of diseases that affects particular nerves known as motor nerves, or motor neurons. In MND, those neurons generate and die and slowly the muscles become weaker. This eventually leads to paralysis. It is also known as Lou Gehrig\'s disease, amyotrophic lateral sclerosis or ALS. - symptoms of MND - MND is a progressive disease that usually starts slowly and gets worse over time. Symptoms sometimes starting on one side of the body and then spreading. Usually, the first things people notice are: - \- Weakness in the hands and grip - \- Slurred speech - \- Weakness in the legs, and a tendency to trip - \- Weakness of the shoulder, making lifting difficult - \- Cramps and muscles twitching - Later on, people with MND: - \- Have little or no movement - \- Have trouble talking, [[breathing]](https://www.healthdirect.gov.au/breathing-problems) and swallowing - \- A few people with MND develop a type of [[dementia]](https://www.healthdirect.gov.au/dementia). - \- If you have MND, your sense of sight, touch, smell, hearing and taste won't be affected. - Causes of MND: - The exact cause of MND is not known. You can't catch MND from somebody. - Generally, MND is believed to be caused because of a combination of environmental, lifestyle and genetic factors. - Most cases of MND occur spontaneously without any identifiable cause. Around 1 in 10 cases are ‗familial' (meaning the condition is inherited) due to a genetic mutation (or error in the gene). - If a person has an MND-related genetic mutation, their children have a 50/50 chance of inheriting the MND-related genetic mutation. - If a person in your family has MND, other people in the family can be tested to see if they have the genetic mutation. - People who inherit the genetic mutation have a high chance of developing MND, but not all people with the genetic mutation will develop MND. - Treatment: - There is no cure, but a lot can be done to ease your symptoms, maintain quality of life and keep you as mobile as possible for as long as possible. - Most people with MND die within 2 to 3 years of developing the condition, however some people can live a long time. - - Epilepsy - Epilepsy is a long-term brain condition where a person has repeated [[seizures]](https://www.healthdirect.gov.au/seizures). It is thought to affect about 3 in every 100 Australians. - Having just one seizure is not considered to be epilepsy --- about half the people who have one seizure never have another seizure. Other conditions such as [[fever]](https://www.healthdirect.gov.au/fever), [[diabetes]](https://www.healthdirect.gov.au/diabetes), [[heart conditions]](https://www.healthdirect.gov.au/heart-and-cardiovascular-conditions) and alcohol withdrawal can also cause seizures. - Epilepsy is not one single condition; rather it is a range of different conditions that can cause seizures. - symptoms of epilepsy: - The symptom of epilepsy is seizures. These are episodes of disrupted electrical activity in the [[brain]](https://www.healthdirect.gov.au/central-nervous-system) and can vary greatly depending on the part of the brain involved. - Seizures can cause symptoms such as a loss of consciousness, unusual jerking movements (convulsions) as well as other unusual feelings, sensations and behaviours. - There are many different types of seizures. Generalised seizures involve the whole brain and therefore the whole body is affected. Focal seizures involve only part of the brain. - Generalised tonic-clonic seizures - Previously known as \'grand mal seizures\', these types of seizures are the most well recognised. The seizure begins with a sudden loss of consciousness, the body then becomes stiff followed by jerking of the muscles. Turning red or blue, tongue-biting and loss of bladder control are common. Confusion, drowsiness, memory loss, headache and agitation can occur on regaining consciousness. - Generalised absence seizures - Previously known as \'petit mal seizures\', these types of seizures usually start in childhood, but can occur in adults. These seizures are brief and involve staring, loss of expression, unresponsiveness and stopping activity. Sometimes eye blinking or upward eye movements are seen. The person usually recovers immediately and resumes their previous activity, with no memory of the event. - Focal seizures - Previously known as \'partial seizures\', start in one area of the brain and affect the parts of the body controlled by that area of the brain. The seizure may involve unusual movements, feelings, sensations or behaviours. People can have different levels of consciousness during focal seizures. - Febrile convulsions - Febrile convulsions are common seizures occurring in about 3 in 100 healthy children up to the age of 6 years. The seizures are generally harmless and associated with an illness causing a fever, such as a viral infection. - Management includes treating the seizure if necessary, as well as treating the underlying cause of the fever. - In the absence of any risk factors for epilepsy, children with febrile convulsions have a similar risk of developing epilepsy to the general population. - Generalised absence seizures - Previously known as \'petit mal seizures\', these types of seizures usually start in childhood, but can occur in adults. These seizures are brief and involve staring, loss of expression, unresponsiveness and stopping activity. Sometimes eye blinking or upward eye movements are seen. The person usually recovers immediately and resumes their previous activity, with no memory of the event. - Focal seizures - Previously known as \'partial seizures\', start in one area of the brain and affect the parts of the body controlled by that area of the brain. The seizure may involve unusual movements, feelings, sensations or behaviours. People can have different levels of consciousness during focal seizures. - Febrile convulsions - Febrile convulsions are common seizures occurring in about 3 in 100 healthy children up to the age of 6 years. The seizures are generally harmless and associated with an illness causing a fever, such as a viral infection. - Management includes treating the seizure if necessary, as well as treating the underlying cause of the fever. - In the absence of any risk factors for epilepsy, children with febrile convulsions have a similar risk of developing epilepsy to the general population. - What causes epilepsy? - The cause of epilepsy is unknown in half of cases. We know that genetics (family history) play an important role. - Seizures or epilepsy can also be caused by anything that causes damage to the brain, including: - [[head injury or trauma]](https://www.healthdirect.gov.au/head-injuries) - [[stroke]](https://www.healthdirect.gov.au/stroke) or brain haemorrhage - brain infection or inflammation, such as in [[meningitis]](https://www.healthdirect.gov.au/meningitis), encephalitis or a brain abscess - brain malformations or tumours - brain diseases, such as [[Alzheimer's disease]](https://www.healthdirect.gov.au/alzheimers-disease) - chronic alcohol or drug use - genetic factors - [[high]](https://www.healthdirect.gov.au/hyperglycaemia-high-blood-sugar) or [[low blood sugar]](https://www.healthdirect.gov.au/hypoglycaemia-low-blood-sugar) and other biochemical imbalances - However, seizures may not develop for years after the damage to the brain occurs. -  - Treatment of epilepsy: - Most people with epilepsy are able to control their seizures with antiepileptic medicines and by avoiding triggers. The type of antiepileptic therapy you need depends on factors such as how old you are and what types of seizures you are having. Many antiepileptic medications require blood tests to make sure the levels in your blood are not too low or too high or causing other medical problems. - Several new treatments are being explored. These include: - surgery on the area of the brain causing the seizures - vagus nerve stimulation --- nerves in the neck are stimulated by a device placed under the skin - a strict medically supervised diet used in some children with epilepsy, called a ketogenic diet - Parkinson\'s disease: - Parkinson\'s disease is a disorder of the nervous system. It results from damage to the nerve cells that produce dopamine, a chemical that is vital for the smooth control of muscles and movement. - Parkinson\'s disease mainly affects [[people aged over 65]](https://www.healthdirect.gov.au/seniors-health), but it can come on earlier. - Symptoms of Parkinson\'s disease: - The main symptoms of Parkinson\'s disease are: - tremor or shaking, often when resting or tired. It usually begins in one arm or hand - muscle rigidity or stiffness, which can limit movement and may be painful - slowing of movement, which may lead to periods of freezing (inability to start moving) and small shuffling steps - stooped posture and balance problems - The symptoms of Parkinson\'s disease vary from person to person as well as over time. Some people also experience: - \- loss of unconscious movements, such as blinking and smiling - \- difficulties with handwriting - \- changes to speech, such as soft, quick or slurred speech - \- [[anxiety]](https://www.healthdirect.gov.au/anxiety) or [[depression]](https://www.healthdirect.gov.au/depression) - \- loss of smell - \- constipation - \- lack of urinary control - \- sleep disturbance - \- fatigue - \- impotence - \- drop in blood pressure leading to dizziness - \- difficulty swallowing and sweating - Treatment: - Medicines - The medicines used to treat Parkinson\'s disease are designed to increase the level of dopamine in the brain. They may be given in pill form or via an injection or tube straight into the small intestine. - Surgery - Deep brain stimulation surgery can be used for some people to reduce the amount of medicine they need. It can reduce the tremor, or lessen wriggling movements in the body. - Lifestyle changes - If you are living with Parkinson\'s, making changes to your lifestyle and physical environment may make it easier. - Healthy diet - Eating a [[high-fibre](https://www.healthdirect.gov.au/high-fibre-foods-and-diet) [diet](https://www.healthdirect.gov.au/high-fibre-foods-and-diet)] of fruit, vegetables and grains, and drinking plenty of water, can help prevent the [[constipation]](https://www.healthdirect.gov.au/constipation) that often accompanies Parkinson\'s disease. Make sure you eat a balanced diet high in omega-3 fatty acids. - Exercise - [[Exercising]](https://www.healthdirect.gov.au/fitness-and-exercise) may increase muscle strength and balance, and reduce [[depression]](https://www.healthdirect.gov.au/depression) and [[anxiety]](https://www.healthdirect.gov.au/anxiety). A physiotherapist can advise about an exercise program and strategies to overcome problems such as freezing of movement and loss of balance. - ​ Cerebral palsy Cerebral palsy is a condition that affects body movements due to brain injury. The injury can happen before, during or after birth and does not get worse over time. The brain damage affects body movement and posture. It often shows up as either floppy or stiff muscles, or involuntary muscle movements. Cerebral palsy can affect movement, coordination, muscle tone and posture. It can also be associated with impaired vision, hearing, speech, eating and learning. The damage to the brain is permanent. There is no cure. Life expectancy is normal or near normal in mild cerebral palsy, but the effects of cerebral palsy can cause stress to the body and premature ageing. What are the types of cerebral palsy? There are 4 main types of cerebral palsy. - Spastic, in which the muscles are weak and stiff and movements are awkward. Either or both arms or legs may be affected, on the same side of the body or different. - Dyskinetic (athetoid), in which the muscles move uncontrollably or cause involuntary postures. This is caused by the muscles of the arms, legs and body contracting and relaxing. If muscles of the face and tongue are affected, talking is difficult and this may cause drooling. - Ataxic, in which movements appear jerky and clumsy due to problems with balance and coordination. It can lead to unsteady walking and difficulty with rapid movement. People with ataxic cerebral palsy may also experience involuntary shaking of the hands. - Mixed, in which the person shows a range of the above characteristics. What are the symptoms of cerebral palsy? Cerebral palsy causes a range of symptoms. The most common ones are: - being stiff or floppy - having exaggerated reflexes - muscle weakness - lack of muscle coordination - uncontrolled body movements - problems with balance and coordination - problems with swallowing, sucking or eating - using one side of the body to reach for things - delay in learning to speak These symptoms can be mild or severe. They usually appear in a child's first 2 years of life. People with cerebral palsy may or may not have other conditions such as intellectual disability, [[epilepsy]](https://www.healthdirect.gov.au/epilepsy), delayed growth, spinal deformities, and troubles with seeing, hearing and speaking. What causes cerebral palsy? Cerebral palsy occurs when there is damage to the developing brain in the area that controls muscle tone (the motor cortex). An injury to the fetus is sometimes caused by low oxygen levels, poor circulation, infection or trauma. In some cases, the brain fails to develop normally in the fetus. Depending on the damage, cerebral palsy affects people in different ways and to different extents. Risk factors for cerebral palsy are: - prematurity and low birth weight - some pregnancy complications - an infection caught by the mother during pregnancy - prolonged loss of oxygen during pregnancy or childbirth, or severe jaundice after birth - injury or bleeding in the baby\'s brain - mutations in the genes that affect the brain\'s development - being a twin, triplet or other multiple birth The cause remains unknown for most babies with cerebral palsy. There is no single cause of cerebral palsy. Advised for medical care: Children with cerebral palsy tend to miss developmental milestones such as crawling, walking and talking. You may be worried about cerebral palsy if your child is slow to develop physical skills or has tight or floppy muscles or an unusual posture. For example, if your child is not walking by 12 to 18 months and is not speaking simple sentences by 24 months, or if they display some of the signs of cerebral palsy listed above, you may need to speak to your early childhood nurse or doctor. For more information on signs that your child may have cerebral palsy, visit the [[Cerebral Palsy Alliance website]](https://cerebralpalsy.org.au/our-research/about-cerebral-palsy/what-is-cerebral-palsy/signs-and-symptoms-of-cp/). How is cerebral palsy managed? Even though cerebral palsy cannot be cured, a lot can be done to manage the condition. Children, in particular, can benefit from the services of a team of health professionals to help with: - mobility - speech, seeing and hearing - eating and drinking - pain - learning - control of bladder and bowel - emotional wellbeing [[Physiotherapists]](https://www.healthdirect.gov.au/physiotherapy) and [[occupational therapists]](https://www.healthdirect.gov.au/occupational-therapy) can help with everyday tasks like sitting, walking, dressing and using the toilet. They may suggest casts, splints or orthotics, and give exercises to help strengthen muscles. As well as expert advice, they can help with equipment such as walking frames, wheelchairs and modified shoes. Medicines such as [[Botox]](https://www.healthdirect.gov.au/medicines/brand/amt%2C3742011000036100/botox), [[diazepam]](https://www.healthdirect.gov.au/medicines/medicinal-product/aht%2C20759/diazepam) or baclofen may be able to help relax stiff or overactive muscles, reducing pain and improving mobility. Medicines may be given as tablets, injections or via surgically implanted pumps. There are special braces to help with muscle imbalance, and surgery and mechanical aids to help overcome other impairments. Medicines may be needed for epilepsy, pain, [[sleep]](https://www.healthdirect.gov.au/sleep-disorders) or eating disorders due to the cerebral palsy. There are also experts who can help with learning, communication and emotional issues that are often experienced by people with cerebral palsy. Adults with cerebral palsy who work may find that their working conditions need to be adapted, with flexible hours, more rest time and changes to the physical environment. Mobility can be an issue, especially in transferring from one place to another, such as from bed to sitting. An assessment of the environment by an occupational therapist may help enable a person to get around any disabling issues. Prevention of cerebral palsy: There is still no way to prevent cerebral palsy. However, making it law to wear seatbelts and use pool fencing and giving rubella vaccinations have all brought the rate of cerebral palsy down in Australia. Sometimes babies who are at high risk of cerebral palsy may receive medications or be treated with cooling therapy to reduce the risk or severity of the condition. Neurofibromatosis Neurofibromatosis is a [[genetic condition]](https://www.healthdirect.gov.au/guide-to-genetic-disorders) characterised by the growth of neurofibromas. These are a type of tumour that is usually benign, or non- cancerous, although in rare cases they can be [[cancerous]](https://www.healthdirect.gov.au/cancer). These neurofibromas can form wherever there are nerve cells in the body. Neurofibromatosis is not curable, but it is manageable and many people with the condition lead normal lives.  Neurofibromas can form wherever there are nerve cells in the body. What are the types of neurofibromatosis? There are 3 types of neurofibromatosis: - **neurofibromatosis type 1 (NF1)** --- the most common form, caused by a change in a gene on chromosome 17 - **neurofibromatosis type 2 (NF2)** --- a very rare form, caused by a change in a gene on chromosome 22 - **schwannomatosis** --- similar to NF2, but not associated with inner ear tumours and hearing loss What are the symptoms of neurofibromatosis? The signs and symptoms differ from person to person, depending on what type of the condition they have. In NF1, benign tumours commonly grow on the skin. A common feature of NF1 is \'café au lait\' spots, which are harmless coffee-coloured skin patches. Most people have 1 or 2 of these spots, but people with NF1 always have 6 or more. In NF1, tumours can also appear on the optic nerve and on the iris in the eye. These tumours might or might not affect vision. In NF2, the benign tumours usually develop in the ears, but they can also be found within the spinal cord and brain. Symptoms can include [[hearing]](https://www.healthdirect.gov.au/hearing-loss) [[loss]](https://www.healthdirect.gov.au/hearing-loss) and problems with swallowing, speech, balance and eye movements. What causes neurofibromatosis? Half of all people affected by neurofibromatosis have inherited it from a parent who has the condition, while others will be the first person in their family to have it. How is neurofibromatosis managed? Neurofibromatosis can\'t be cured, but any symptoms that arise can be treated or managed. Regular medical attention may be required throughout childhood and into adulthood, particularly if tumours become cancerous, although this is rare. Sciatica Sciatica is a condition that can lead to pain in the back and legs. It occurs when pain travels along the path of the sciatic nerve. This nerve starts in the lower spine, and travels through the hip and buttock and down the back of the leg to the foot. There are a range of different causes of sciatica. In most cases, the condition gets better over time, either on its own or with treatment. What are the symptoms of sciatica? Symptoms of sciatica can include pain, tingling and numbness in the leg. Sciatica is felt as [[nerve pain]](https://www.healthdirect.gov.au/nerve-pain) radiating from the buttock down the back of the leg, often when sitting, sneezing, coughing or going to the toilet. You may also feel lower back pain, and/or tingling, pins and needles, numbness or weakness in your leg. Although sciatica pain can be severe, most people find their symptoms improve in time. As sciatica is seen as a more serious low back condition, it's advisable to see your doctor within the first few days of getting the symptoms. To diagnose sciatica, the doctor will take a medical history and examine your spine and legs. Medical care should be contacted if bladder or bowels are uncontroled, or have weakness, numbness or severe pain. What causes sciatica? The causes of sciatica include spinal injury or trauma, bone spurs or other growths, narrowing of the spinal canal, or tight or swollen muscles in the buttock. In many cases, people can't pinpoint a specific injury that caused the condition. Risk factors for sciatica include: - age-related changes to the spine - obesity, which can put extra pressure on the spine - occupations where you twist the spine or pick up heavy loads - prolonged sitting - [[diabetes]](https://www.healthdirect.gov.au/diabetes), which can increase the risk of nerve damage How is sciatica treated? The choice of sciatica therapies depends on the length of symptoms and severity of your condition. These therapies include: - special back care education - rest - physical therapies - medication treatment - lifestyle changes - surgery Mild sciatic usually goes away in time. When you first experience sciatica, 1 or 2 days' bed rest may be needed. However, it\'s important to return to activity as soon as possible, to help your spine stay strong. Sciatica treatment includes [[pain relief medicines]](https://www.healthdirect.gov.au/pain-relief-medicines) such as [[paracetamol]](https://www.healthdirect.gov.au/medicines/medicinal-product/aht%2C20948/paracetamol), anti-inflammatory drugs such as [[ibuprofen]](https://www.healthdirect.gov.au/medicines/medicinal-product/aht%2C21286/ibuprofen) and [[physiotherapy]](https://www.healthdirect.gov.au/physiotherapy). Most people with sciatica get better with conservative treatments such as physiotherapy. You should see your doctor again self-care measures fail to improve your pain, if your pain lasts longer than a week, is severe or becomes progressively worse. If your symptoms persist, an injection of anaesthetic into the spine may be needed or, in rare cases, surgery. Can sciatica be prevented? Looking after your back, managing your weight, and improving your general physical condition can all help prevent sciatica. Doing physical therapy at home, such as muscle strengthening exercise, can help to prevent sciatica coming back. Shingles Shingles is a viral infection that causes a painful, blistering rash. It is caused by the varicella-zoster virus, which is the same virus that causes [[chickenpox]](https://www.healthdirect.gov.au/chickenpox). You can only get shingles if you have had chickenpox in the past. The shingles rash develops into painful blisters that may also be itchy, usually on one side of the body, either on the face, chest, back, abdomen or pelvis. They can take several weeks to settle. In 1 in 10 people, the pain and tingling of shingles can last for months or even years. This is called post-herpetic [[neuralgia]](https://www.healthdirect.gov.au/nerve-pain). What are the symptoms of shingles? The initial symptoms of shingles include: - pain - a burning, tingling or itching sensation - a stabbing sensation - sensitivity to touch - numbness in the affected area of the body - sensitivity to light - fever and/or headache - fatigue Two to 3 days after these symptoms appear, a painful rash will appear on the sensitive area of skin, usually on one side of the body in the area of one skin nerve (called a dermatome). At first this rash consists of painful red bumps that quickly develop into fluid-filled blisters, which will eventually have a crusty surface. The rash can last for 10 to 15 days. What causes shingles? Anyone who has had chickenpox in the past can develop shingles. The chickenpox virus stays in the nerve cells near the spine but is not active. Shingles occurs when the virus becomes active again. Shingles can occur at any age, but it usually affects people over 40. About 1 in 3 people who have not been immunised against chicken pox or shingles will develop shingles at some stage during their lifetime. Shingles often occurs with no known trigger. It is more likely to occur if you: - are aged 60 or older - are experiencing physical and emotional stress - have HIV and AIDS - have had an organ transplant - have recently had a bone marrow transplant - have a condition which requires treatment that affects the immune system, such as chemotherapy for cancer Usually, people only get shingles once in their lives. But sometimes, especially if you have a weakened immune system, you might get repeated infections. You cannot catch shingles from someone who has the condition. If you have not had chickenpox, you can catch chickenpox by coming into direct contact with fluid on the blisters of someone who has shingles.  If you've had chickenpox in the past, you can develop shingles. The virus will stay in your nerve cells but not be active, shingles occurs when it becomes active again. When should seeking a doctor? when experiencing the following: - [[confusion]](https://www.healthdirect.gov.au/confusion) - memory loss - severe [[headache]](https://www.healthdirect.gov.au/headaches) - symptoms that affect your eye area - [[a temperature]](https://www.healthdirect.gov.au/fever) of 38°C or higher How is shingles treated? There is no cure for shingles, but antiviral medicine may relieve the symptoms and help prevent complications. See your doctor for a prescription of antiviral medicines as soon as possible after symptoms develop. Treatment should be started within 3 days of the shingles rash appearing. If you are pregnant, talk to your doctor about whether antivirals are right for you. Over-the counter medicines, such as [[paracetamol]](https://www.healthdirect.gov.au/paracetamol) and non-steroidal anti- inflammatories, can be used for [[pain relief]](https://www.healthdirect.gov.au/pain-relief-medicines). If over-the-counter medicines are not controlling your pain, your doctor may prescribe other medicines. There are several things you can do to help manage the condition. They include the following. - Try to keep the rash dry and clean. - Cover the rash if possible to avoid spreading the virus to others. Use a non-stick dressing. Do not use antibiotic creams or sticking plasters on the blisters since they may slow down the healing process. - Try not to scratch the rash. Scratching may cause infection and scarring of the blisters. - After a bath or shower, gently pat yourself dry with a clean towel. Do not rub or use the towel to scratch yourself and do not share towels. - Wear loose cotton clothes around the parts of the body that are affected. - Cool compresses, baths or ice packs may help with the discomfort. Do not apply ice packs directly to the skin. Wrap the ice pack in a light towel and place it gently over the dressing. Wash the towel in hot water after use. - If the blisters are open, applying creams or gels is not recommended because they might increase the risk of a secondary bacterial infection. - Avoid contact with people who may be more at risk, such as pregnant women who are not immune to chickenpox, people who have a weak immune system and babies less than one month old. - Do not share towels, play contact sports, or go swimming. Wash your hands often. Prevention of shingles: A vaccination called Zostavax reduces the likelihood of developing shingles. If you are over 50, you can talk to your doctor about whether you need it. It is recommended for everyone over 60. It is given free of charge in Australia to people aged 70 to 79. Vaccination will not guarantee that you will not get shingles, but it will reduce your chance of developing the condition. Zostavax is not the same as the vaccine used to protect against chickenpox. Read more about the [[chickenpox vaccine]](https://www.healthdirect.gov.au/chickenpox#prevented) [[here]](https://www.healthdirect.gov.au/chickenpox#prevented). Shingles vaccine Vaccination is your best protection against shingles. This table explains how the vaccine is given, who should get it, and whether it is on the National Immunisation Program Schedule. Some diseases can be prevented with different vaccines, so talk to your doctor about which one is appropriate for you. -- -- -- -- -- -- -- -- Complications of shingles ========================= In many people, shingles gets better without any complications. However, in others, several complications can occur. These include: - ongoing pain from post-herpetic neuralgia. This is less common in younger people - shingles occurring in the eye area could result in temporary or permanent vision loss. If you do have shingles in your eye, your doctor may refer you to an eye specialist for treatment - the shingles rash could become infected and antibiotics may be needed 1. **Which of the following is the function of Trochlear nerve?** a. Hearing. b. Movement of tongue. c. Moving eye. d. Shrugging shoulders. 2. **Sympathetic nervous system:** e. Its origin is thoraco-lumber. f. Its Pre-ganglionic neuron is long. g. Its ganglia near to the organ. h. Its distribution is localized. 3. **Which of the following is a systemic function of the parasympathetic nervous system on the eye?** i. Contraction of the radial muscles of the pupil. j. Contraction of superior tarsal muscles of the eyelid. k. Contraction circular muscles of the pupil. l. Contraction of retro-occular muscles. 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