Nervous System Physiology 2024 PDF

Nervous System 2024 Nervous System 2024  The Nervous System Two Organ Systems Control All the Other Organ Systems. – Nervous system characteristics Rapid response Brief duration – Endocrine system characteristics Slower response Long duration  01Ner...

Nervous System 2024 Nervous System 2024  The Nervous System Two Organ Systems Control All the Other Organ Systems. – Nervous system characteristics Rapid response Brief duration – Endocrine system characteristics Slower response Long duration  01Nervous Sysytem https://www.youtube.com/watch?v=44B0ms3XPKU  The Nervous system The nervous system is a complicated web of nerve fibers and cells that run to and from the brain and spinal cord throughout the body. It innervates every organ in the body and is responsible for carrying messages to the brain to be interpreted.  Facts About The Nervous System The more we learn, the more electrical connections are generated in our brains. These connections help in establishing memory, and the more they are reinforced, the stronger the memory. As they say practice makes perfect! electrical impulses that flow through neurons and nerve cells are conducted by the flow of tiny chemical.  Facts About The Nervous System In total there are 43 pairs of nerves in the peripheral nervous system, 12 pairs are connected directly with the brain, and 31 pairs are connected to the spinal cord. The connections between neurons in the brain create a network that resembles a Spider web! It is a myth that humans use only 10% of their brain! only 4% of the cells are active and involved in electrical impulse generation and transmission. The rest of the cells are in a dormant or resting phase.  Convolutional Neural Network (CNN) Convolutional Neural Network (CNN) is a type of Deep Learning neural network architecture commonly used in Computer Vision. Computer vision is a field of Artificial Intelligence that enables a computer to understand and interpret the image or visual data. CNN FOUR PRIMARY FUNCTIONS OF NERVOUS SYSTEM 1. Sensing the world  Vision, Hearing, Smell, Taste, Touch 2. Transmitting information 3. Processing information 4. Producing a response  The Nervous System Two Anatomical Divisions – Central nervous system (CNS) Brain Spinal cord – Peripheral nervous system (PNS) All the neural tissue outside CNS Afferent division (sensory input) Efferent division (motor output) – Somatic nervous system – Autonomic nervous system Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings  Neural Tissue Organization Anatomic Organization of CNS Neurons – White matter—Bundles of axons (tracts) that share origins, destinations, and functions Anatomic Organization of PNS Neurons – Ganglia—Groupings of neuron cell bodies – Nerve—Bundle of axons supported by connective tissue Spinal nerves –To/from spinal cord Cranial nerves –To/from brain Organization of the Nervous System  Components of the Nervous System Central Nervous System – Brain – Spinal Cord Peripheral Nervous System – Sensory and Motor Nerves – Cranial Nerves – Spinal Nerves  02Brain https://www.youtube.com/watch?v=HVGlfcP3ATI  The Human Brain Complex 1.4 kg in weight Pre frontal cortex 2% of body weight 20% of oxygen 15% of our cardiac input 10% of all energy  Functions of Brain Functions of the brain: Major parts of the brain: Interprets sensations Cerebrum Determines perception Frontal lobes Stores memory Parietal lobes Reasoning Occipital lobes Makes decisions Temporal lobes Coordinates muscular movements Insula Regulates visceral activities Cerebellum Determines personality Brainstem Midbrain Pons Medulla oblongata 19  Large front part of the brain FUNCTIONS: – Voluntary activity – Memory – Language – Receives and responds to sensory signals – Controls motor functions The Central Nervous Brain Waves System (Electroencephalogram)  Cerebral Cortex Three kinds of functional areas Motor areas: movement Sensory areas: perception Association areas: integrate diverse information to enable purposeful action  The Cerebrum Controls conscious activities, intelligence, memory, language, muscles. Wrinkled with countless folds and grooves and covered with an outer layer of gray matter called the cerebral cortex. Divided into 4 lobes  Frontal lobe Personality, behavior, emotions Judgment, planning, problem solving Speech: speaking and writing (Broca’s area) Body movement (motor strip) Intelligence, concentration, self awareness  Parietal lobe Interprets language, words Sense of touch, pain, temperature (sensory strip) Interprets signals from vision, hearing, motor, sensory and memory Spatial and visual perception  Occipital lobe Interprets vision (color, light, movement)  Temporal lobe Understanding language (Wernicke’s area) Memory Hearing Sequencing and organization  Basal Nuclei Also called basal ganglia Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Masses of gray matter Longitudinal fissure deep within cerebral Caudate Right cerebral hemisphere hemispheres nucleus Basal Putamen nuclei Caudate nucleus, Globus pallidus putamen, and globus pallidus Thalamus Cerebellum Produce dopamine Hypothalamus Brainstem Control certain muscular Spinal cord activities Primarily by inhibiting motor functions 28  Thalamus Gateway for sensory impulses heading to cerebral cortex Receives all sensory impulses (except smell) Channels impulses to appropriate part of cerebral cortex for interpretation Hypothalamus Maintains homeostasis by regulating visceral activities Links nervous and endocrine systems (hence some say the neuroendocrine system 29  The Central Nervous System What are the Functions of the Hypothalamus? – Produce emotions and behavioral drives – Coordinate nervous and endocrine systems – Secrete hormones – Coordinate voluntary and autonomic functions – Regulate body temperature Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings  Hypothalamus Control of endocrine system through pituitary gland  Hypothalamus Main visceral control center – Autonomic nervous system (peripheral motor neurons controlling smooth and cardiac muscle and gland secretions): heart rate, blood pressure, gastrointestinal tract, sweat and salivary glands, etc. – Emotional responses (pleasure, rage, sex drive, fear) – Body temp, hunger, thirst sensations – Some behaviors – Regulation of sleep-wake centers: circadian rhythm (receives info on light/dark cycles from optic nerve) – Control of endocrine system through pituitary gland – Involved, with other sites, in formation of memory  Smaller part of the brain ,towards the back FUNCTIONS: Coordinates all movement Helps maintain posture, muscle control, and balance  Cerebellum Receives messages from most of the muscles in your body The cerebellum is most directly involved in coordinating voluntary movements. It is also responsible for a number of functions including motor skills such as balance, coordination, and posture.  03BrainStem https://www.youtube.com/watch?v=dEgaaJWRf7g  Brainstem Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hypothalamus Three parts: Thalamus Diencephalon 1. Midbrain 2. Pons Corpus callosum 3. Medulla Oblongata Corpora quadrigemina Midbrain Cerebral aqueduct Pons Reticular formation Medulla oblongata Spinal cord 36  Brain Stem  The brainstem controls several important functions of the body including:  Alertness  Arousal  Breathing  Blood Pressure  Digestion  Heart Rate  Other Autonomic Functions  Relays Information Between the Peripheral Nerves and Spinal Cord to the Upper Parts of the Brain  Pons Regulates breathing. In addition, the pons is involved in the transmission of signals to and from other structures in the brain, such as the cerebrum or the cerebellum. The pons is also involved in sensations such as hearing, taste, and balance. Finally, the pons is also involved in the regulation of deep sleep.  Medulla Oblongata The medulla oblongata is located in the lower portion of the brainstem. It is very important in things like heart rate and blood pressure. It's responsible for many reflexes in the body, or involuntarily controls, such as vomiting, sneezing, and coughing.  Cerebrospinal Fluid CSF Made in choroid plexuses (roofs of ventricles) Cushions and nourishes brain Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. Cerebrospinal fluid. The cerebrospinal fluid circulates in the subarachnoid space around the brain and spinal cord, and in the ventricles of the brain.  CSF circulation: through ventricles, median and lateral apertures, subarachnoid space, arachnoid villi, and into the blood of the superior sagittal sinus CSF: -Made in choroid plexus -Drained through arachnoid villus  Blood-Brain Barrier Tight junctions between endothelial cells of brain capillaries, instead of the usual permeability Highly selective transport mechanisms Allows nutrients, O2, CO2 Not a barrier against uncharged and lipid soluble molecules; allows alcohol, nicotine, and some drugs including anesthetics  04Blood-Brain Barrier https://www.youtube.com/watch?v=e9sN9gOEdG4  Memory How humans form memories is poorly understood. “Working memory” appears to be distinct from long-term memory. There may be short-term memory as well, things remembered for a few days. Is this because the memory disappears, or because it cannot be retrieved? Models of Memory Models of Memory Craik & Lockhart, 1972 47  Peripheral Nervous System Cranial nerves arising from the brain Somatic fibers connecting to the skin and skeletal muscles Autonomic fibers connecting to viscera Spinal nerves arising from the spinal cord Somatic fibers connecting to the skin and skeletal muscles Autonomic fibers connecting to viscera 48  Peripheral Nervous System Sensory (Afferent) – convey impulses from sensory receptors to CNS – Afferent (sensory) neurons Motor (Efferent) – convey impulses away from CNS to periphery – Efferent (motor) neurons  Peripheral Nervous System Nerves are either motor nerves or sensory nerves. – Efferent or motor nerves innervate muscles and glands. In order to accomplish this, they conduct nerve impulses from the CNS to the muscles and glands. – Afferent or sensory nerves send sensory information and nerve impulses from sensory receptors in the skin, muscles, and joints to the brain. Structure of a Peripheral Nerve Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fascicle Peripheral nerve Epineurium Motor neuron ending Axon Perineurium Endoneurium Node of Ranvier Schwann cell Sensory receptor Myelin sheath Neurilemma  04Neuron https://www.youtube.com/watch?v=6qS83wD29PY  05What are neurons and how do they work https://www.youtube.com/watch?v=FcMK7qLQ07k  The Neuron Dendrites receive signals. The cell body integrates signals. The axon transmits action potential. The myelin sheath makes the signal travel faster. Synaptic terminals transmit signals.  06How Neurotransmission Works https://www.youtube.com/watch?v=p5zFgT4aofA  Neurotransmitters There are two kinds of neurotransmitters – INHIBITORY and EXCITATORY. stimulate the brain calm the brain  Neurotransmitters Acetylcholine (ACh) Norepinephrine (NE)( also known as noradrenaline) Dopamine(D) Serotonin (5HT) Glutamate Gamma-aminobutyric acid (GABA)  Acetylcholine (Ach) Cholinergic pathways thought to be involved in cognition (esp. memory) and our sleep/wake cycle parasympathetic nervous system regulating bodily functions such as heart rate, digestion, secretion of saliva and bladder function Alzheimer’s disease and myathesia gravis (weakness of skeletal muscles) Anti-cholinergic effects  07Acetyl Choline https://www.youtube.com/watch?v=yPq8qDaj184  Norepinephrine (NE) attention, alertness and arousal NE levels fluctuate with sleep and wakefulness and changes in attention and vigilance mood, affective states and anxiety antidepressant  Dopamine(D) complex movement and cognition Emotional responses such as euphoria or pleasure (seen in amphetamine/cocaine use). Significant role in motor control  Great influences on Serotonin (5HT) behaviour. Low serotonin activity is associated with aggression, suicide, impulsive eating and disinhibited sexual behaviour particularly the onset of sleep depression and anxiety disorders delusions, hallucinations (LSD) negative symptoms of schizophrenia  Glutamate Glutamate is found in all cells of the body control the opening of ion channels that allow calcium to pass into nerve cells producing impulses Blocking of glutamate receptors produces ( eg. By PCP) schizophrenic like symptoms Over exposure of neurons to glutamate cause cell death seen in stroke and Huntington’s disease (PN).  Gamma-aminobutyric acid (GABA) Inhibitory and its pathways are only found within the CNS. control excitatory neurotransmitters in the brain and controlling spinal and cerebral reflexes. anxiety disorders decreased GABA can lead to seizure activity Benzodiazepines and barbiturates sedative medication act on GABA  Synapse Neurons usually do not connect directly to one another. A gap called a synapse controls the transmission of signals. Neurotransmitters cross the synapse and stimulate the next neuron.  Electrical Transmission The Information that flows in the neurone Approximately 10 billion neurons are responsible for receiving, organising and transmitting information in the central nervous system Ions in the intracellular fluid (inside the cell) have a negative charge Ions in extracellular fluid (outside the cell) have a positive charge attracting positively charged cells (cations) ‘Potential difference’ between the inside and the outside of the cell  08Electrical Transmission https://www.youtube.com/watch?v=b2ctEsGEpe0  Ions are sodium, potassium, calcium and chloride ‘voltage gated’ Resting Potential vs. Action potential  Chemical Neurotransmission The flow of neurotransmitter across the synapse Neurotransmitter; – Made in the pre synaptic neurone – Stored inactively in synaptic vesicles – Released from the synaptic vesicles into the synapse – Binds to receptors – Binds to reuptake transporters to be taken back into the neurone – Is degraded by specific enzymes  Resting potential  Using active transport, the neuron moves Na+ ions to the outside of the cell and K+ ions to the inside of the cell.  Large molecules in the cell maintain a negative charge.  Action potential  On receiving a stimulus, sodium gates and potassium channels open briefly, allowing these ions to diffuse.  The gates close, and active transport restores the resting potential.  09Action Potential Explained https://www.youtube.com/watch?v=ZAmUjvgoO0A  Nerve Impulse A change in charge that travels as a wave along the membrane of a neuron Called an action potential Depends on the movement of sodium ions (Na+) and potassium ions (K+) between the interstitial fluid and the inside of the neuron.  Resting Potential Sodium ions are in large concentration along the outside of the cell membrane Potassium ions are in large concentration along the inside of the cell membrane Human Anatomy, 3rd edition Prentice Hall, © 2001  Beginning of a Nerve Impulse Requires a stimulus of adequate strength Membrane is irritable – Neuron may respond to a stimulus and convert it to an impulse. When? – If above threshold  Starting Depolarization –a a Nerve Impulse stimulus depolarizes the neuron’s membrane A depolarized membrane allows sodium (Na+) to flow inside the membrane The exchange of ions initiates an action potential in the neuron Marieb, Essentials of Human Anatomy and Physiology, 8th edition, 2006  If the action The Action Potential potential starts, it is propogated over the entire axon Potassium ions rush out of the neuron after sodium ions rush in – Repolarizes the membrane http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/files/Bio%20102/Bio%20102%20lectures/nervous%20system/neuron6.gif  Return to Resting Potential Sodium-potassium pump restores original configuration – Requires ATP http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/files/Bio%20102/Bio%20102%20lectures/nervous%20system/neuron6.gif  Nerve Impulse Propagation The impulse continues to move away from the cell body Impulses travel faster when fibers have a myelin sheath Marieb, Essentials of Human Anatomy and Physiology, 8th edition, 2006  Continuation of the Nerve Impulse Impulses are ableBetween Neurons to cross a synapse to another nerve – Neurotransmitter is released from the axon terminal (synaptic knob) into synaptic cleft – The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter Marieb, Essentials of Human Anatomy and Physiology, 8th edition, 2006  Synaptic Cleft Marieb, Essentials of Human Anatomy and Physiology, 8th edition, 2006 Postsynaptic Membrane Receptor Marieb, Essentials of Human Anatomy and Physiology, 8th edition, 2006  Synapse Human Anatomy, 3rd edition Prentice Hall, © 2001 Section 35-3 The Nervous System is divided into Central nervous Peripheral nervous system system Motor nerves which consists of Sensory nerves that make up Somatic nervous Autonomic nervous system system which is divided into Sympathetic Parasympathetic nervous system nervous system  The Peripheral Nervous System The 12 pairs of cranial nerves are responsible for the special senses of smell, sight, and hearing/balance, and control movement of the eye, jaw, face, tongue, and muscles of the neck, back, and shoulders. They also provide sensation from the face, neck, and upper chest and autonomic innervation to thoracic and abdominopelvic organs. The Peripheral Nervous The Cranial Nerves System Peripheral nervous system… The network of nerves branching out throughout the body from the brain and spinal cord is called the peripheral nervous system. In addition to the 31 pairs of spinal nerves mentioned in the slides on the spinal cord, there are 12 pairs of cranial nerves that attach to the brain: I. The olfactory nerve carries sensory input for smell Peripheral nervous system… II. The optic nerve carries sensory input for vision III. The oculomotor nerve controls muscles of the eye and eyelid IV. The trochlear nerve controls the eyeball V. The trigeminal nerve controls the face, nose, mouth, forehead, top of head, and jaw. VI. The abducens nerve (ab DŪ senz) also controls the eyeball Peripheral nervous system… VII. The facial nerve controls muscles of the face and scalp, and part of the tongue for sense of taste. VIII. The auditory or cochlear nerve provides sensory input for hearing and equilibrium. IX. The glossopharyngeal nerve controls saliva, swallowing, and taste. Peripheral nervous system… X. The vagus nerve is the longest cranial nerve, extending to and controlling the heart, lungs, stomach, and intestines. XI. The accessory nerve permits movement of the head and shoulders. XII.The hypoglassal nerve controls the muscles of the tongue.  Cranial Nerve Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Superior ganglion Vagus nerve (X) Meningeal branch Auricular branch of vagus nerve Pharyngeal branch Inferior ganglion Mixed nerve Palate of vagus nerve Nerve XI Somatic motor to muscles Superior laryngeal nerve Nerve XII of speech and swallowing Carotid body Autonomic motor to Recurrent laryngeal Left vagus nerve viscera of thorax and nerve Cardiac nerves abdomen Lung Sensory from pharynx, Heart larynx, esophagus, and viscera of thorax and Liver Stomach abdomen Spleen Pancreas Kidney Small intestine Large intestine 94  Peripheral Nervous System Spinal Nerves – there are 31 pairs of spinal nerves branching off the spinal cord. – 8 cervical – 12 thoracic – 5 lumbar – 5 sacral – 1 coccygeal  Dermatomes The surface of the skin is divided into specific areas called dermatomes There are 31 segments of the spinal cord, each with a pair (right and left) of ventral (anterior) and dorsal (posterior) nerve roots that innervate motor and sensory function, respectively. The anterior and posterior nerve roots combine on each side to form the spinal nerves as they exit the vertebral canal through the intervertebral foramina or neuroforamina.  Dermatomes The 31 spine segments on each side give rise to 31 spinal nerves, which are composed of 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal spinal nerve. Dermatomes exist for each of these spinal nerves, except the first cervical spinal nerve. Sensory information from a specific dermatome is transmitted by the sensory nerve fibers to the spinal nerve of a specific segment of the spinal cord.  Clinical significance Dermatomes are useful to help localize neurologic levels, particularly in radiculopathy. Effacement or encroachment of a spinal nerve may or may not exhibit symptoms in the dermatomic area covered by the compressed nerve roots in addition to weakness, or deep tendon reflex loss. Innervation of the skin: dermatomes- each spinal nerves innervates a skin zone  Motor Component Somatic Nervous System (Voluntary) – conduct impulses from CNS to skeletal muscles Autonomic Nervous System (Involuntary) – convey impulses from CNS to smooth muscle, cardiac muscle and glands  The Peripheral Nervous System Nerve Plexus —A complex, interwoven network of nerves Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings  The Peripheral Peripheral Nervous System Nerves and Nerve Plexuses  The Peripheral Nervous System Reflex—An automatic involuntary motor response to a specific stimulus  REFLEX ARC https://www.youtube.com/watch?v=aaQWxko6qmk  The Peripheral Nervous System Reflex—An automatic involuntary motor response to a specific stimulus Arrival of stimulus and activation of receptor Stimulus  Dorsal Arrival of Activation of a root stimulus and sensory neuron activation of receptor Receptor Stimulus KEY Sensory neuron (stimulated)  Dorsal Sensation Arrival of Activation of a root relayed to stimulus and sensory neuron the brain by activation of collateral receptor Receptor Stimulus Information processing in CNS KEY Sensory neuron (stimulated) Excitatory interneuron  Dorsal Sensation Arrival of Activation of a root relayed to stimulus and sensory neuron the brain by activation of collateral receptor REFLEX Receptor ARC Stimulus Ventral root Information processing in CNS Activation of a motor neuron KEY Sensory neuron (stimulated) Excitatory interneuron Motor neuron (stimulated)  Dorsal Sensation Arrival of Activation of a root relayed to stimulus and sensory neuron the brain by activation of collateral receptor REFLEX Receptor ARC Stimulus Effector Ventral root Information processing in CNS Response Activation of a by effector motor neuron KEY Sensory neuron (stimulated) Excitatory interneuron Motor neuron (stimulated) Stretching of muscle tendon stimulates muscle spindles Muscle spindle (stretch receptor) Stretch Spinal cord REFLEX ARC Contraction Activation of motor neuron produces reflex muscle contraction Stretching of muscle tendon stimulates muscle spindles Muscle spindle (stretch receptor) Stretch Spinal cord Stretching of muscle tendon stimulates muscle spindles Muscle spindle (stretch receptor) Stretch Spinal cord REFLEX ARC Contraction Activation of motor neuron produces reflex muscle contraction  The Peripheral Nervous System The Flexor Reflex, a Type of Withdrawal Reflex Organization of Nervous System Nervous System Central Nervous Peripheral System Nervous Brain & spinal System cord Autonomic N.S. Somatic N.S.  10Autonomic Nervous System – Physiology https://www.youtube.com/watch?v=D96mSg2_h0c  Autonomic Nervous System 2 divisions: – Sympathetic “Fight or flight” “E” division – Exercise, excitement, emergency, and embarrassment – Parasympathetic “Rest and digest” “D” division – Digestion, defecation, and diuresis  Peripheral Nervous System Autonomic division of the nervous system can be subdivided into 2 divisions: (1) Parasympathetic – Decreases heart rate, bronchiole dilation, blood glucose, blood to skeletal muscle – Increases digestion, pupil size, urinary output – “rest and digest” (2) Sympathetic – Decreases digestion, pupil size, urinary output – Increases heart rate, bronchiole dilation, blood glucose, blood to skeletal muscle – “fight or flight”  Peripheral Nervous System PNS can be subdivided into 2 divisions: (1) Autonomic – Cranial & spinal nerves connecting CNS to heart, stomach, intestines, glands – Controls unconscious activities  Peripheral Nervous System (2) Somatic – Cranial & spinal nerves connecting CNS to skin & skeletal muscles – Oversees conscious activities Adrenergic and Cholinergic Synaptic Transmission  Parasympathetic vs. Sympathetic Divisions  Sympathetic Effects Fight, Fright or flight response Release of Neurotransmitters (NT)- Norepinephrine (NT) from postganglionic fibers Epinephrine (NT) from adrenal medulla  Sympathetic Effects Mass activation prepares for intense activity Heart rate (HR) increases Bronchioles dilate Blood [glucose] increases  Sympathetic Effects GI motility decreases Contraction of sphincters Relaxation of Detrusor muscle Ciliary muscle Mydriasis  Parasympathetic Effects Normally not activated as a whole Stimulation of separate parasympathetic nerves. Release ACh as NT Relaxing effects- Decreases HR. Dilates visceral blood vessels. Increases digestive activity.  Parasympathetic Effects Bronchonstriction GI motility increases Relaxation of sphincters Contraction of Detrusor muscle Ciliary muscle Miosis Somatic Nervous System Structure Single motor neuron cell leading from the CNS directly to the muscle Cell body of motor neurons located in CNS The Autonomic Nervous System What Is The Autonomic Nervous System? Branch of nervous system that coordinates cardiovascular, digestive, excretory, and reproductive functions The Autonomic Nervous System What are the Two Divisions of the ANS? – Sympathetic division “Fight or flight” system – Parasympathetic division “Rest and digest” system The Autonomic Nervous System The two divisions of the ANS operate largely without our awareness. The sympathetic division increases alertness, metabolic rate, and muscular abilities; the parasympathetic division reduces metabolic rate and promotes visceral activities such as digestion.  The Autonomic Nervous System The Somatic and Autonomic Nervous Systems  The Autonomic Nervous System The Somatic and Autonomic Nervous Systems The Organization of the Somatic and Autonomic Nervous System The Autonomic Nervous System The Sympathetic Division Figure 8-34 The Autonomic Nervous System What are the Effects of Sympathetic Activation? – Generalized response in crises – Increased alertness – Feeling of euphoria and energy – Increased cardiovascular activity – Increased respiratory activity – Increased muscle tone The Autonomic Nervous System The Parasympathetic Division The Autonomic Nervous System What are the Effects of Parasympathetic Activation? – Relaxation – Food processing – Energy absorption – Brief effects at specific sites  Autonomic nervous System Neurotransmitters of ANS Neurotransmitters of sympathetic nervous system Neurotransmitters of parasympathetic nervous system Sympathetic Nervous System Neurotransmitters at- A. Preganglionic nerve endings B. Postganglionic nerve endings C. Target tissue Sympathetic Nervous System Neurotransmitters at- A. Preganglionic nerve endings  Acetylcholine (ACh) B. Postganglionic nerve endings  Norepinephrine (NE) Sympathetic Nervous System Neurotransmitters at- Target tissue Epinephrine (Ep) Norepinephrine (NE) Parasympathetic Nervous System Neurotransmitters at- A. Preganglionic nerve endings  Acetylcholine (ACh) B. Postganglionic nerve endings  Acetylcholine (ACh) Aging and the Nervous System What are Age-Related Changes? – Reduction in brain size and weight – Loss of neurons – Decreased brain blood flow – Changes in synaptic organization of the brain  Autonomic Nervous System (ANS) The autonomic or involuntary nervous system is that portion of the nervous system which regulates the activity of cardiac muscle, smooth muscle, and the glands. The ANS has two parts: – Sympathetic – Parasympathetic Comparison of autonomic and somatic motor systems- the motor unit of autonomic system includes two motor neurons: preganglionic neuron (myelinated) has an axon that synapses with the postganglionic neuron (unmyelinated) in autonomic ganglion, then the axon of the postganglionic neuron synapses with the viscera. A somatic motor unit contains one myelinated axon per innervated muscle cell  Autonomic Nervous System Structure Two neurons involved in efferent pathway (CNS to effector) 1rst (preganglionic) has cell body in CNS – synapses with 2nd in the autonomic ganglion 2nd (postganglionic) sends signal from auton. gang. to the effector organ 11Autonomic Nervous System https://www.youtube.com/watch?v=eeQ6c5nu-ck  Autonomic Nervous System Sympathetic – stimulates viscera – Prepares the body for emergency situations (“fight or flight” response to stress) – Fear, emergency, physical exertion, and embarrassment are responded to by this system – This system shifts energy and blood toward the skeletal muscles, cardiac muscles, and respiration  Autonomic Nervous System Parasympathetic – inhibits viscera – Energy conservation system – Restores body energy during rest – Responses toward digestion, elimination of waste, and decreases heart rate Sympathetic and X Parasympathetic Divisions Sympathetic (thoracolumnar) – dominates in stressful situations – prepares body for activity ('Fight or Flight’) – adrenergic effects (use norepinephrine) Parasympathetic (craniosacral) – dominates during relaxed situations – precise control over the body – cholinergic effects (use acetylcholine)  Sympathetic vs. Parasympathetic Effects Organ Sympathetic Parasympathetic Heart increases HR decreases HR Blood vessels to visceral organs constrict dilate Blood vessels to heart + skeletal muscle dilate constrict Digestive tract decreases motility increases motility  THE STRESS REACTION When stress occurs, the sympathetic nervous system is triggered. Norepinephrine is released by nerves, and epinephrine is secreted by the adrenal glands. By activating receptors in blood vessels and other structures, these substances ready the heart and working muscles for action. Acetylcholine is released in the parasympathetic nervous system, producing calming effects. The digestive tract is stimulated to digest a meal, the heart rate slows, and the pupils of the eyes become smaller. The neuroendocrine system also maintains the body’s normal internal functioning.  Chronic stress When glucocorticoids or adrenaline are secreted in response to the prolonged psychological stress commonly encountered by humans, the results are not ideal. Normally, bodily systems gear up under stress and release hormones to improve memory, increase immune function, enhance muscular activity, and restore homeostasis. If you are not fighting or fleeing, but standing frustrated in a supermarket checkout line or sitting in a traffc jam, you are not engaging in muscular exercise. Yet these systems continue to be stimulated, and when they are stimulated chronically, there are different consequences: Memory is impaired, immune function is suppressed, and energy is stored as fat. Response to stress Senses  Sensory receptors Receptors are found in the sense organs. They receive stimuli from the environment and transmit stimuli to neurons. Primary humans senses: photoreception, chemoreception, mechanoreception, thermoreception.  Thermoreception  Free nerve endings in the skin sense changes in temperature (differences rather than absolutes).  These are directly transmitted through the PNS.  Mechanoreception Hearing is a form of mechanoreception. Ears gather sound waves from the environment. The inner ear bones amplify sounds. Sounds are transmitted to the cochlea.  Sound transmission Within the cochlea, hair cells on the basilar membrane vibrate to certain frequencies, and send signals down the auditory nerve. Loud sounds can damage these sensitive hairs permanently.  Photoreception Sight is photoreception. Light enters the eye through the cornea and pupil. Light is focused by the lens. Light strikes the retina, and stimulates receptors.  Photoreceptors Light breaks pigments in the receptor cells, releasing energy that stimulates neurons connecting to the optic nerve. Rod cells detect amount of light, cone cells distinguish colors.  Chemoreceptioin Taste is one form of chemoreception. Taste buds detect certain ions dissolved in saliva. Tastes: salty, sweet, sour, bitter,  Chemoreception Smell is another form of chemoreception. Receptors in the olfactory patch in the human nose can distinguish between about 1000 different chemicals in the air.  “Flavor” What we sense as the “flavor” of food is not taste alone. Smell and taste together create the sensation of “flavor.” This is why things don’t “taste” good when we have a cold; we lose the sense of “flavor.”  Chemoreception The sense of pain is another form of chemoreception. Injured tissues release chemicals as a response. These chemicals stimulate free nerve endings in the skin and the stimulation is perceived as pain.  The End Any Questions???