Nervous System Anatomy and Physiology PDF

THE NERVOUS SYSTEM The nervous system consists of the brain, spinal cord. Sensory organs, and all of the nerves that connect these organs with the rest of the body. These organs are responsible for the control of the body and communication among its parts. The brain and s...

THE NERVOUS SYSTEM The nervous system consists of the brain, spinal cord. Sensory organs, and all of the nerves that connect these organs with the rest of the body. These organs are responsible for the control of the body and communication among its parts. The brain and spinal cord form the control center known as the central nervous system (CNS), where information is evaluated and decisions made. NERVOUS SYSTEM PHYSIOLOGY FUNCTIONS OF THE NERVOUS SYSTEM SENSORY The sensory function of the nervous system involves collecting information from sensory receptors that monitor the body’s internal and external conditions. INTEGRATION The process of integration is the processing of the many sensory signals that are passed into the CNS at any given time. THE NERVOUS SYSTEM ANATOMY NERVOUS TISSUES The majority of the nervous system is tissue made up of two classes of cells: neurons and neuroglia. NEURONS Also known as nerve cells, communicate within the body by transmittingelectrochemical signals. Neurons look quite different from other cells in the body due to the many long cellular processes that extend from their central cell body. NERVOUS SYSTEM ANATOMY Neuroglia Neuroglia, also known as glial cells, act as the “helper” cells of the nervous system. Each neuron in the body is surrounded by anywhere from 6 to 60 neuroglia that protect, feed, and insulate the neuron.  Brain The brain, a soft, wrinkled organ that weighs about 3 pounds. Is located inside the cranial cavity, where the bones of the skull surround and protect it. BRAIN SECTIONS BRAIN HAS 6 SECTION: - CEREBRUM - CEREBELLUM - DIENCEPHALON - MIDBRAIN - PONS - MEDULLA OBLONCATA NERVOUS SYSTEM ANATOMY SPINAL CORD The spinal cord is a long. Thin mass of bundled neurons that carries information through the vertebral cavity of the spine beginning at the medulla oblongata of the brain on its superior end and continuing inferiorly to the lumbar region of the spine. In the lumbar region. The spinal cord separates into a bundle of individual nerves called the cauda equina (due to its resemblance to a horse’s tail) that continues inferiorly to the sacrum and Coccyx. The white matter of the spinal cord functions as the main Conduit of nerve signals to the body from the brain. The grey matter of the spinal cord integrates reflexes to stimuli. NERVES Nerves are bundles of axons in the peripheral nervous system (PNS) that act as information highways to carry signals between the brain and spinal cord and the rest of the body. Each axon is wrapped in a connective tissue sheath called the endoneurium. Individual axons of the nerve are bundled into groups of axons called fascicles, wrapped in a sheath of connective tissue called the perineurium. NERVOUS SYSTEM ANATOMY AFFERENT, EFFERENT. AND MIXED NERVES. Some of the nerves in the body are specialized for carrying information in only one direction, similar to a one-way street. CRANIAL NERVES Extending from the inferior side of the brain are 12 pairs of cranial nerve  Each cranial nerve pair is identified by a Roman numeral 1 to 12 based upon its location along the anterior-posterior axis of the brain. CRANIAL NERVES Each nerve also has a descriptive name (e.g. olfactory, opti etc.) that identifies its function or location. The cranial nerves provide a direct connection to the brain for the special sense organs, muscles of the head, neck, and shoulders. the heart, and the Cf tract. SPINAL NERVES Nerves extending from the left and right sides of the spinal cord are 31 pairs of spinal nerves. The spinal nerves are mixed nerves that carry both sensory and motor signals between the spinal cord and specific regions of the body. FUNCTIONS OF THE CRANIAL NERVES 12 CRANIAL NERVES HAS A SPECIFIC FUNCTION WITHIN THE NERVOUS SYSTEM. 1. The olfactory nerve 2. The optic nerve 3,4,5. Oculomotor, trochlear, and abducens nerves 6. The facial nerve (VII 7. The vestibulocochlear nerve (Vill) 8. The glossopharyngeal nerve (IX) 9. The vagus nerve (X) 10. The accessory nerve (XI) 11. The hypoglossal nerve (XII) SPINAL NERVES 8 paired Cervical nerves 12 pairs of Thoracic nerves 5 pairs of Lumbar nerves 5 pairs of Sacral nerves 1 pair of Coccygeal nerves MENINCES The meninges are the protective coverings of the central nervous system (CMS). They consist of three layers the dura mater, arachnoid mater, and pia mater. DURA MATER The dura mater, which means "tough mother." is the thickest, toughest, and most superficial layer of meninges. ARACHNOID MATER The arachnoid mater, which means "spider-like mother," is much thinner and more delicate than the dura mater. PIA MATER The pia mater, which means "tender mother." is a thin and delicate layer of tissue that rests on the outside of the brain and spinal cord. CEREBROSPINAL FLUID The space surrounding the organs of the CMS is filled with a clear fluid known as cerebrospinal fluid (CSF). CSF is formed from blood plasma by special structures called choroid plexuses CEREBROSPINAL FLUID Newly created CSF flows through the inside of the brain in hollow spaces called ventricles and through a small cavity in the middle of the spinal cord called the central canal. CSF also flows through the subarachnoid space around the outside of the brain and spinal cord. CSF is constantly produced at the choroid plexuses and is reabsorbed into the bloodstream at structures called arachnoid villi. SENSE ORGANS All of the bodies many sense organs are components of the nervous system. What are known as the special senses-vision. Taste. smell hearing, and balance- are all detected by specialized organs such as the eyes, taste buds, and olfactory epithelium. DIVISIONS OF THE NERVOUS SYSTEM CENTRAL NERVOUS SYSTEM The brain and spinal cord together form the central nervous system. or CMS. The CNS acts as the control center of the body by providing its processing, memory, and regulation systems. The CMS takes in all of the conscious and subconscious sensory information from the body's sensory receptors to stay aware of the body's internal and external conditions. Using this sensory information, it makes decisions about both conscious and subconscious actions to take to maintain the body's homeostasis and ensure its survival. DIVISIONS OF THE NERVOUS SYSTEM PERIPHERAL NERVOUS SYSTEM The peripheral nervous system (PHS) includes all of the parts of the nervous system outside of the brain and spinal cord. These parts include all of the cranial and spinal nerves. ganglia, and sensory receptors. SOMATIC NERVOUS SYSTEM The somatic nervous system (SHS) is a division of the PNS that includes all of the voluntary efferent neurons. DIVISIONS OF THE NERVOUS SYSTEM AUTONOMIC NERVOUS SYSTEM The autonomic nervous system (ANS) is a division of the PNS that includes all of the involuntary efferent neurons. The ANS controls subconscious effectors such as visceral muscle tissue, cardiac muscle tissue, and glandular tissue. SOMATIC NERVOUS SYSTEM The somatic nervous system (SNS) is a division of the PNS that includes all of the voluntary efferent neurons. DIVISIONS OF THE NERVOUS SYSTEM 2 DIVISIONS OF THE AUTONOMIC NERVOUS SYSTEM IN THE BODY: SYMPATHETIC PARASYMPATHETIC DIVISIONS OF THE NERVOUS SYSTEM ENTERIC NERVOUS SYSTEM The enteric nervous system (ENS) is the division of the ANS that is responsible for regulating digestion and the function of the digestive organs. The ENS receives signals from the central nervous system through both the sympathetic and parasympathetic divisions of the autonomic nervous system to help regulate its functions. The ENS is often called the "brain of the gut" or the body's "second brain." DIVISIONS OF THE NERVOUS SYSTEM REFLEXES Reflexes are fast. involuntary responses to stimuli. The most well-known reflex is the patellar eflex, which is checked when a physician's taps on a patient's knee during a physical examination. Reflexes are integrated in the gray matter of the spinal cord or in the brain stem. Reflexes allow the body to respond to stimuli very quickly by sending responses to effectors before the nerve signals reach the conscious parts of the brain. SENSORY PHYSIOLOGY All sensory receptors can be classified by their structure and by the type of stimulus that they defect. Structurally, there are 3 classes of sensory receptors free nerve endings, encapsulated nerve endings, and specialized cells. Free nerve endings are simply free dendrites at the end of a neuron that extend into a tissue. Pain, heat, and cold are all sensed through free nerve endings. DIVISIONS OF THE NERVOUS SYSTEM 6 MAJOR CLASSES OF RECEPTORS: MECHANORECEPTORS Mechanoreceptors. Mechanoreceptors are sensitive to mechanical stimuli like touch, pressure, vibration, and blood pressure. NOCICEPTORS Nociceptors respond to stimuli such as extreme heat, cold, or tissue damage by sending pain signals to the CHS. 6 MAJOR CLASSES OF RECEPTORS: PHOTORECEPTORS In the retina detect light to provide the sense of vision. CHEMORECEPTORS Detect chemicals in the bloodstream and provide the senses of taste and smell. OSMORECEPTORS Monitor the osmolarity of the blood to determine the body's hydration levels. THERMORECEPTORS It detect temperatures inside the body and in its surroundings. SPECIAL SENSES SPECIAL SENSES Special senses refer to the five sensory systems that provide humans and many other animals with specific and distinct sensory information about their environment. These senses are considered "special" because they are more complex and specialized compared to the general or somatic senses, such as touch and pressure. The functions of the five special senses include: VISION Sight or vision is the capability of the eye(s) to focus and detect images of visible light on photoreceptors in the retina of each eye that generates electrical nerve impulses for varying colors. hues, and brightness. HEARING Hearing or audition is the sense of sound perception. TASTE Taste refers to the capability to detect the taste of substances such as food, certain minerals, and poisons, etc. SMELL Smell or olfaction is the other "chemical" sense: odor molecules possess a variety of features and, thus, excite specific receptors more or less strongly: this combination of excitatory signals from different receptors makes up what we perceive as the molecule's smell. TOUCH Touch or somatosensory. also called tactition or mechanoreception, is a perception resulting from activation of neural receptors, generally in the skin including hair follicles. but also in the tongue, throat, and mucosa. THE EYE AND VISION Vision is the sense that has been studied most of all the sensory receptors in the body 70% are in the eyes. ANATOMY OF THE EYE Vision is the sense that requires the most "learning". and the eye appears to delight in being fooled: the old expression "You see what you expect to see" is often very true. EXTERNAL AND ACCESSORY STRUCTURES The accessory structures of the eye include the extrinsic eye muscles, eyelids, conjunctiva, and lacrimal apparatus. EYELIDS Anteriorly, the eyes are protected by the eyelids. which meet at the medial and lateral corners of the eye, the medial and lateral commissure (canthus), respectively. EXTERNAL AND ACCESSORY STRUCTURES EYELASHES They help filter out dust and debris from entering the eye and provide additional protection. TARSAL CLANDS Modified sebaceous glands associated with the eyelid edges are the tarsal glands: these glands produce an oily secretion that lubricates the eye: ciliary glands. modified sweat glands, lie between the eyelashes. EXTERNAL AND ACCESSORY STRUCTURES CONJUNCTIVA A delicate membrane, the conjunctiva, lines the eyelids and covers part of the outer surface of the eyeball it ends at the edge of the cornea by fusing with the corneal epithelium. LACRIMAL APPARATUS The lacrimal apparatus consists of the lacrimal gland and a number of ducts that drain the lacrimal secretions into the nasal cavity. LACRIMAL CLANDS The lacrimal glands are located above the lateral end of each eye: they continually release a salt solution (tears) onto the anterior surface of the eyeball through several small ducts. LACRIMAL CANALICULI The tears flush across the eyeball into the lacrimal canaliculi medially, then into the lacrimal sac, and finally into the nasolacrimal duct, which empties into the nasal cavity. LYSOZYME Lacrimal secretion also contains antibodies and lysozyme, an enzyme that destroys bacteria: thus, it cleanses and protects the eye surface as it moistens and lubricates it. EXTRINSIC EYE MUSCLE Six extrinsic, or external, eye muscles are attached to the outer surface of the eye: these muscles produce gross eye movements and make it possible for the eyes to follow a moving object: these are the lateral rectus, medial rectus, superior rectus, inferior rectus, inferior oblique, and superior oblique. THE EAR: HEARING AND BALANCE At first glance, the machinery for hearing and balance appears very crude. ANATOMY OF THE EAR Anatomically, the ear is divided into three major area: the external, or outer; the middle ear, and the internal, or inner, ear. EXTERNAL (OUTER EAR) The external, or outer, ear is composed of the auricle and the external acoustic meatus. AURICLE The auricle, or pinna, is what most people call the “ear”- well-shaped structure surrounding the auditory canal opening. EXTERNAL (OUTER EAR) EXTERNAL ACOUSTIC MEATUS The external acoustic meatus is a short, narrow chamber carved into the temporal bone of the skull: in its skin-lined walls are the ceruminous glands, which secrete waxy, yellow cerumen or earwax, which provides a sticky trap for foreign bodies and repels insects. EXTERNAL (OUTER EAR) TYMPANIC MEMBRANE Sound waves entering the auditory canal eventually hit the tympanic membrane, or eardrum, and cause it to vibrate: the canal ends at the ear drum, which separates the external from the middle ear. MIDDLE EAR PHARYNGOTYMPANIC TUBE. The pharyngotympanic tube runs obliquely downward to link the middle ear cavity with the throat, and the mucosae lining the two regions are continuous. OSSICLES The tympanic cavity is spanned by the three smallest bones in the body, the ossicles, which transmit the vibratory motion of the eardrum to the fluids of the inner ear. INTERNAL (INNER) EAR The internal ear is a maze of bony chambers, called the bony, or osseous, labyrinth, located deep within the temporal bone behind the eye socket. SUBDIVISIONS The three subdivisions of the bony labyrinth are the spiraling, pea-sized cochlea, the vestibule, and the semicircular canals. INTERNAL (INNER) EAR Perilymph The bony labyrinth is filled with a plasma-like fluid called perilymph. Membranous labyrinth Suspended in the perilymph is a membranous labyrinth, a system of membrane sacs that more or less follows the shape of the bony labyrinth. Endolymph The membranous labyrinth itself contains a thicker fluid called endolymph. CHEMICAL SENSES: TASTE AND SMELL The receptors for taste and olfaction are classified as chemoreceptors because they respond to chemicals in solution. OLFACTORY RECEPTORS AND THE SENSE OF SMELL Even though our sense of smell is far less acute than that of many other animals, the human nose is still no slouch in picking up small differences in odors. SENSE OF SMELL OLFACTORY RECEPTORS The thousands of olfactory receptors, receptors for the sense of smell, occupy a postage stamp-sized area in the roof of each nasal cavity. The olfactory receptor cells are neurons equipped with olfactory hairs, long cilia that protrude from the nasal epithelium and are continuously bathed by a layer of mucus secreted by underlying glands. SENSE OF SMELL OLFACTORY FILAMENTS When the olfactory receptors located on the cilia are stimulated by chemicals dissolved in the mucus, they transmit impulses along the olfactory filaments, which are bundled axons of olfactory neurons that collectively make up the olfactory nerve. OLFACTORY NERVE The olfactory nerve conducts the impulses to the olfactory cortex of the brain CHEMICAL SENSES: TASTE AND SMELL The receptors for taste and olfaction are classified as chemoreceptors because they respond to chemicals in solution. TASTE BUDS AND THE SENSE OF TASTE The word taste comes from the Latin word "taxare". which means "to touch, estimate, or judge". SENSE OF TASTE TASTE BUDS The taste buds, or specific receptors for the sense of taste, are widely scattered in the oral cavity; of the 10. 000 or so taste buds we have most are on the tongue. PAPILLAE The dorsal tongue surface is covered with small peg- like projections, or papillae. SENSE OF TASTE CIRCUMVALLATE AND FUNGIFORM PAPILLAE. The taste buds are found on the sides of the large round circumvallate papillae and on the tops of the more numerous fungiform papillae. GUSTATORY CELLS. The specific cells that respond to chemicals dissolved in the saliva are epithelial cells called gustatory cells. SENSE OF TASTE GUSTATORY HAIRS. Their long microvilli- the gustatory hairs- protrude through the taste pore, and when they are stimulated, they depolarize and impulses are transmitted to the brain. FACIAL NERVE The facial nerve (VII) serves the anterior part of the tongue. SENSE OF TASTE GLOSSOPHARYNGEAL AND VAGUS NERVES The other two cranial nerves- the glossopharyngeal and vagus- serve the other taste bud- containing areas. BASAL CELLS. Taste bud cells are among the most dynamic cells in the body, and they are replaced every seven to ten days by basal cells found in the deeper regions of the taste buds. ENDOCRINE SYSTEM ENDOCRINE SYSTEM The endocrine system is a complex regulatory system in the human body that consists of a network of glands, hormones, and target organs. Its primary function is to regulate various physiological processes and maintain homeostasis by producing, releasing, and transporting chemical messengers called hormones. These hormones act as signals, traveling through the bloodstream to specific target cells or organs, where they influence and control a wide range of bodily functions. ENDOCRINE SYSTEM FUNCTION The endocrine system is responsible for regulating a range of bodily functions through the release of hormones. Hormones are secreted by the glands of the endocrine system, traveling through the bloodstream to various organs and tissues in the body. The hormones then tell these organs and tissues what to do or how to function. ENDOCRINE SYSTEM FUNCTION Some examples of bodily functions that are controlled by the endocrine system include: - Metabolism - Growth and development - Sexual function and reproduction - Heart rate - Blood pressure - Appetite - Sleeping and waking cycles - Body temperature ENDOCRINE SYSTEM ORGANS The endocrine system is made up of a complex network of glands, which are organs that secrete substances. The glands of the endocrine system are where hormones are produced, stored, and released. Each gland produces one or more hormones, which go on to target specific organs and tissues in the body. ENDOCRINE SYSTEM ORGANS The glands of the endocrine system include: HYPOTHALAMUS While some people don't consider it a gland, the hypothalamus produces multiple hormones that control the pituitary gland. It's also involved in regulating many Pituitary The pituitary gland is located below the hypothalamus. The hormones it produces affect growth and reproduction. They can also control the function of other endocrine glands. ENDOCRINE SYSTEM ORGANS PITUITARY The pituitary gland is located below the hypothalamus. The hormones it produces affect growth and reproduction. They can also control the function of other endocrine glands. PINEAL This gland is found in the middle of your brain. It's important for your sleep-wake cycles. ENDOCRINE SYSTEM ORCANS THYROID The thyroid gland is located in the front part of your neck. It's very important for metabolism. PARATHYROID Also located in the front of your neck. the parathyroid gland is important for maintaining control of calcium levels in your bones and blood. ENDOCRINE SYSTEM ORGANS THYMUS Located in the upper torso, the thymus is active until puberty and produces hormones important for the development of a type of white blood cell called a T cell. ADRENAL One adrenal gland can be found on top of each kidney. These glands produce hormones important for regulating functions such as blood pressure, heart rate, and stress response. PANCREAS The pancreas is located in your abdomen behind your stomach. Its endocrine function involves controlling blood sugar levels. ENDOCRINE SYSTEM HORMONES Hormones are the chemicals the endocrine system uses to send messages to organs and tissue throughout the body. Once released into the bloodstream, they travel to their target organ or tissue, which has receptors that recognize and react to the hormone. Below are some examples of hormones that are produced by the endocrine system: ECONDITIONS THAT CAN AFFECT THE ENDOCRINE SYSTEM Sometimes, hormone levels can be too high or too low. When this happens, it can have a number of effects on your health. The signs and symptoms depend on the hormone that's out of balance. HYPERTHYROIDISM Hyperthyroidism happens when your thyroid gland makes more thyroid hormone than necessary. This can be caused by a range of things including autoimmune conditions. Some common symptoms of hyperthyroidism include: fatigue, nervousness, weight loss, diarrhea, issues tolerating heat, fast heart rate, trouble sleeping. Hyperthyroidism happens when your thyroid gland makes more thyroid hormone than necessary. This can be caused by a range of things, including autoimmune conditions. Some common symptoms of hyperthyroidism include: fatigue, nervousness, weight loss, diarrhea, issues tolerating heat, fast heart rate, trouble sleeping. HYPERTHYROIDISM Treatment depends on how severe the condition is, as well as its underlying cause. Options include medications, radioiodine therapy, or surgery. GRAVES DISEASE Is an auto immune disorder and common form of hyperthyroidism. In people with Craves disease, the immune system attacks the thyroid, which causes it to produce more thyroid hormone than normal. HYPOTHYROIDISM Hypothyroidism occurs when your thyroid doesn't produce enough thyroid hormone. Like hyperthyroidism, it has many potential causes.  Some common symptoms of hypothyroidism include: fatigue, weight gain, constipation, issues tolerating the cold, dry skin and hair, slow heart rate, irregular periods, and fertility issues. Treatment of hypothyroidism involves supplementing your thyroid hormone with medication CUSHING SYNDROME Cushing syndrome happens due to high levels of the hormone cortisol. Common symptoms of Cushing syndrome include: weight gain, fatty deposits in the face, midsection, or shoulders, stretch marks, particularly on the arms, thighs, and abdomen, slow healing of cuts, scrapes, and insect bites, thin skin that bruises easily, irregular periods, and decreased sex drive and fertility in males Treatment depends on the cause of the condition and can include medications, radiation therapy, or surgery. ADDISON DISEASE Addison disease happens when your adrenal glands don't produce enough cortisol or aldosterone. Some symptoms of disease include: fatigue, weight loss, abdominal pain, low blood sugar, nausea or vomiting. diarrhea, irritability, a craving for salt or salty foods. and irregular periods. Treatment of Addison disease involves taking medications that help to replace the hormones that your body isn't producing enough of. DIABETES Diabetes refers to a condition in which your blood sugar levels aren't regulated properly. People with diabetes have too much glucose in their blood (high blood sugar). There are two types of diabetes: type 1 diabetes and type 2 diabetes. Some common symptoms of diabetes include: fatigue, weight loss, increased hunger or thirst, frequent urge to urinate, irritability, and frequent infections. PUTANGINA TAPOS NA RIN, AYOKO NA