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55 Cards in this Set

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Nervous tissue
is made up of just two principal populations: neurons and supporting cells referred to as neuroglia, or glial cells. The N in the CNS include astrocytes, oligodendroctyes, microglia, and epedymal cells. The most important glial cell in the PNS in the neural structures outside the CNS, are schwann cells and satellite cells.
Neuroglia
serve the needs of the delicate neurons by bracing & protecting them. They act as phagocytes, myelinate the cytoplasmic extensions of the neurons, play a role in capillary-neuron exchanges, and control the chemical enviroment around neurons. Have fibrous cellular extensions unlike neurons, they are not capable of generating & transmitting nerve impulses, a capability that is highly developed in neurons.
Neurons
basic functional units of nervous tissue. Highly specialized to transmit messages from one part of the body to another. All have a cell body from which slender processes of fibers extend. Although neuron cell bodies are typically found in the CNS in clusters called nuclei, occasionally they reside in ganglia. They make up the gray matter of the NS. Neuron processes running through the CNS form tracts of white matter; in the PNS they form periphreal nerves.
Neuron cell body
contains a large round nucleus surrounded by cytoplasm. The cytoplasm is riddled with neurofibrils & with darkly staining structures called Nissl bodies. the Cytoskeleton elements of the neuron have support & intracellular transport function. Nissl bodies, an elaborate type of Rough ER, are involved in the metabolic activities of the cell.
2 types of neuron processes
Dendrites are receptive regions and Axons generate and conduct nerve impulses. Neurons have only one axon but have many dendrites, depending on the neuron type.
Classification by Structure
Structually, neurons may be different according to the # of processes attatched to the cell body. In unipolar neurons, one very short process which divides into perphreal & central processes, extends from the cell body. Functionally, only the most distal portions of the periphreal process act as receptive endings, the rest acts as an axon along with the central process. Nearly all neurons that conduct impulses toward the CNS are unipolar. Bipolar neurons have two processes attatched to the cell body. This neuron type is quite rare, typically found only as part of the receptor apparatus of the eye, ear, and olfactory mucosa. Multipolar neurons, all classified as dendrites except for a single axon. Most neurons in the brain & spinal cord (CNS neurons) & those whose axons carry impulses away from the CNS fall into this last category.
Schwann cells
wrap themselves tightly around the axon in jellyroll fashion. During the wrapping process, the cytoplasm is squeezed from between adjacent layers of schwann cell membranes, so that when the process is completed a tight core of plasma membrane material encompasses the membrane. is referred to as the neurilemma.
Nodes of Ranvier
Gaps or indentations in the sheath aka: neurofibril nodes.
Oligodendroctyes
W/ in the CNS myelination is accomplished by glial cells called oligodendroctyes. These CNS sheaths do not exhibit the neurilemma seen in fibers myelinated by schwann cells. Because of its chemical composition, myelin insulates the fibers & greatly increases the speed of neurotransmission by neuron fibers.
A neuron is excited by...
Other neurons when their axons release neurotransmitters close to its dendrites or cell body. The electrical current produced travels across the cell body & down the axon. The axon begins just to distal slightly enlarged cell body structure called the axon hillock. The point at which the axon hillock narrows to the axom diameter is referred to as teh initial segment. The axon ends in many small structures called axon terminals, or synaptic knobs, which form synapses or junctions with neurons or effector cells. These terminals store the neurotransmitter chemical in tiny vesicles. Each axon terminal is seperated from the cell body or dendrites of the next postsynaptic neuron by a tiny gap called the synaptic cleft. No actual physical connection between neurons, only very close. When an impulse reaches the axon terminal, some of the synaptic vesicles rupture and release neurotransmitter into the synaptic cleft. The nt. then diffuses across the s.c. to bind to membrane receptors on the next neuron, initiating a synaptic potential.
Classification by function
In general, neurons carrying impulses from sensory receptors in the internal organs, the skin, skeletal muscles, joints, or special sensory organs are termed sensory or afferent neurons. Neurons carrying activiating impulses from the CNS to the viscera and/or body muscles and glands are termed motor or efferent neurons. Motor neurons are most often multipolar & their cell bodies are almost always located in the CNS. The third functional category of neurons is the association neurons or interneurons, which are situated between & contribute pathways that connect sensory & motor neurons. Their cell bodies are always located w/ in the CNS and they are multipolar neurons structurally.
Neurons have 2 major phsiological properties
Excitablilty or the ability to respond to stimuli & convert them into nerve impulses, and conductivity, the ability to transmit the impulse to other neurons, muscles or glands.
Resting neuron
the exterior surface of the membrane is slightly more postively charged than inner surface. This difference in electrical charge on the 2 dies of the membrane results in a voltage across the plama membrane referred to as the resting membrane potential, and a neuron in this sate is said to be polarized. In the resting state, the predominant intracellular ion is potassium and sodium ions are found in greater concentration in the extracellular fluid. The resting membrane potential is maintained by a very active sodium-potassium pump, which transports sodium out of the cell and potassium into the cell.
Depolarization
When a neuron is stimulated, the membrane becomes more permeable to sodium ions and potassium diffuses into the cell, making the interious of the membrane less negative. This is known as depolarization. if the stimulus is of subthreshold intensity, the depolarization is limited to a small area of the membrane, but if the stimulus reaches threshold, a nerve impulse is generated. in a motor neurons the impulse is generated at the axon hilock, and in sensory neurons the impulse is generated in the most distal part of the axon.
Action potential
During generation of the nerve impulse, or action potential, the membrane becomes increasingly permeable to sodium ions. Depoloarization proceeds until the membrane polarity reverses, making the inside face positive and the outisde face negative.
Cerebral hemispheres
are the most superior portion of the brain. The entire surface is thrown into elevated ridges of tissue called gryi that are septerated by shallow grooves called sulci or depper grooves called fissures. Many of the fissures and gyri are divided by a single deep fissure, the longitudinal fissure. The central sulcus divides the frontal lobe from the parietal love and the lateral sulcus divides the temporal lobe from the parietal lobe. The pariet-occipital sulcus on the medial surface of each hemisphere divides the occipital lobe from the parietal lobe.
Diencephalon
somtimes considered the most superior portion of the brain stem, is embryologically part of the forebrain, along with the cerebral hemispheres. Include: olfactory bubls & tracts, optic nerves, optic chiasma, optic tracts, pituitary gland & mammillary bodies. the major internal structures of the diencephalon are the thalmus (major integrating & relay station for sensory impulses passing upward to the cortical sensory area for localization and interpreation), hypothalmus (regulation of body temperature, water balance & fat and carbohydrate metabolism as well as in other activities (sex, hunger thirst)). epithalmus (pineal body or gland & the choroid plexus which forms the cerebrospinal fluid).
Brain stem
Brain stem structures- the cerebral peduncles (fiber tracts in the midbrain connecting the pons below w/ cerebrum above), the pons, and the medulla oblongata. Pons means bridge. and the pons consists primarily of motor & sensory fiber tracts connecting the brain w/ the lower CNS centers. the lowest brain stem region, the medulla oblongata, is also composes primarily of fiber tracts. The medulla also houses many vital autonmic centers involved in the control of heart rate, respitory rhythm & blood pressure as well as involving centers involved in vomiting, swallowing etc.
Cerebellum
Cauliflower like cerebellum, which projects dorsally from under the occipital lobes of the cerebrum. the cerebellum has 2 major hemispheres and a convulted surface. it also has an outer cotrex made up of gray matter w/ an inner region of white matter.
Cranial nerves
CN 1: OLFACTORY
CN 2: OPTIC
CN 3: OCULOMOTOR
CN 4: TROCHLEAR
CN 5: TRIGEMINAL
CN 6: ABDUCENS
CN 7: FACIAL
CN 8: VESTIBULOCOCHLEAR
CN 9: GLOSSOPHARYNGEAL
CN 10: VAGUS
CN 11: ACCESORY
CN 12: HYPOGLOSSAL
CRANIAL NERVE 1
OLFACTORY
PURELY SENSORY- CARRIES AFFERENT IMPULSES ASSOCIATED WITH THE SENSE OF SMELL.
*SMELL*
CRANIAL NERVE 2
OPTIC
PURELY SESORY- CARRIES AFFERENT IMPULSES ASSOCIATED WITH VISION
*EYE*
CRANIAL NERVE 3
OCULOMOTOR
PRIMARILY MOTOR- WHICH DIRECT THE EYEBALL & TO LEVATOR PALPEBRAE MUSCLES OF THE SUPERIOR EYELID. PARASYMPATHETIC FIBERS TO IRIS AND SMOOTH MUSCLE CONTROLLING LENS SHAPE. *PUPIL DIAMTER8
CRANIAL NERVE 4
TROCHLEAR
PRIMARILY MOTOR- AN EXTRINSIC EYE MUSCLE
*EYE MUSCLES*
CRANIAL NERVE 5
TRIGEMINAL
MIXED- SENSORY AND MOTOR. MAJOR SENSORY NERVE OF FACE, CONDUCTS SENSORY IMPULSES FROM SKIN OF FACE AND ANTERIOR SCALP, FROM MUCOSAE OF MOUTH & NOSE, & FROM SURFACE OF EYES; MANIBULAR DIVISION ALSO CONTAINS MOTOR FIBERS THAT INNERVATE MUSCLES OF MASTICATION & MUSCLES OF THE FLOOR OF MOUTH
CRANIAL NERVE6
ABDUCENS
CARRIES MOTOR FIBERS TO LATERAL RECTUS MUSCLE OF EYE
*EYE MUSCLES*
CRANIAL NERVE 7
FACIAL
MIXED- FACIAL EXPRESSION & PARASYMPATHETIC MOTOR FIBERS TO LACRIMAL & SALIVARY GLANDS; CARRIES SENSORY FIBERS FROM TASTE RECEPTORS OF TONGUE.
*TASTE, SMILING, WHISTLING, CLOSE EYES*
CRANIAL NERVE 8
VESTIBULOCOCHLEAR
PURELY SENSORY- TRANSMITS IMPULSES ASSOCIATED WITH SENSE OF EQUILIBRIUM FROM VESTIBULAR APPARATUS AND SEMICIRCULAR CANALS; COCHLEAR BRANCH TRANSMITS IMPULSES ASSOCIATED WITH HEARING
*HEARING & EQUILIBRIUM*
CRANIAL NERVE 9
GLOSSOPHARYNGEAL
MIXED- MOTOR FIBERS SERVE PHARYNGEAL MUSCLES AND PARASYMPATHETIC MOTOR FIBERS SERVE SALIVARY GLANDS; SENSORY FIBERS CARRY IMPULSES FROM PHARYNX, TONSILS, (TASTE BUDS) POSTERIOR TONGUE, AND FROM CHEMORECEPTORS OF CARTOID ATERY.
*TONGUE, GAG REFLEX*
CRANIAL NERVE 10
VAGUS
MIXED- FIBERS CARRY SOMATIC MOTOR IMPULSES TO PHARYNX & LARNYX AND SENSORY FIBERS FROM SAME STRUCTURES; VERY LARGE PORTION IS COMPOSED OF PARASYMPATHETIC MOTOR FIBERS WHICH SUPPLY HEART AND SMOOTH MUSCLES OF ABDOMINAL VISCERAL ORGANS; TRANSMITS SENSORY IMPULSES FROM VISCERA
*MAIN PART OF THE PARASYMPATHETIC SYSTEM*
CRANIAL NERVE 11
ACCESORY
MIXED- PRIMARILY IN MOTOR FUNCTION- PROVIDES SOMATIC MOTOR FIBERS TO STERNOCLEIDOMASTOID AND TRAPEZIUS MUSCLES OF SOFT PALATE, PHARYNX AND LARNYX,
*NECK MUSCLES*
CRANIAL NERVE 12
HYPOGLOSSAL
MIXED BUT PRIMARILY MOTOR IN FUNCTION- CARRIES SOMATIC MOTOR FIBERS TO MUSCLES OF TONGUE
*STICKING YOUR TONGUE OUT*
ANATOMY OF THE SPINAL CORD
ENCLOSED W/ IN THE VERTEBRAL CANAL OF THE SPINAL COLUMN, THE SPINAL CORD EXTENDS FROM THE FORAMEN MAGNUM OF THE SKULL TO THE FIRST OR SECOND LUMBAR VERTEBRA, WHERE IT TERMIATES IN THE CONE SHAPED CONUS MEDULLARIS. THE THE BRAIN, THE CORD IS CUSHOINED & PROTECTED BY MENINGES. THE DURA MATAR & ARACHNOID MENINGEAL COVERINGS EXTEND BEYOND THE CONUS MEDULLARIS, TO S2, AND THE FILUM TERMINALE, A FIBEROUS EXTENTION OF THE PIA MATER, EXTENDS EVEN FARTHER TO ATTATCH TO THE POSTERIOR COCCYX. DENTICULATE LIGAMENTS, SAW TOOTHED SHELVES OF PIA MATER, SECURE THE SPINAL CORD TO THE BONY WALL OF THE VETERBRAL COLUMN ALL ALONG ITS LENGTH.
HAS 31 PAIRS OF SPINAL NERVES.
31 PAIRS OF SPINAL NERVES
NAMED ACCORDING TO THEIR POINT OF ISSUE. ALL SPINAL NERVES ARE MIXED NERVES. C
*C1-T1
*T2-T12
*L1-L5
*S1-S4
CERVICAL PLEXUS
ARISES FROM THE VENTRAL RAMI OF C1 TO C5 TO SUPPLY MUSCLES OF THE SHOULDER & NECK. THE PHRENIC NERVE (MAY CAUSE HICCUPS)
BRACHIAL PLEXUS
IS LARGE & COMPLEX. ARISING FROM THE VENTRAL RAMI OF C5 TO C8 & T1. THE PLEXUS AFTER BEING REARRANGED CONSECUTIVELY INTO TRUNKS DIVISIONS & CORDS, FINALLY BECOMES SUBDIVIDED INTO 5 MAJOR PERIPHREAL NERVES. THE AXILLARY NERVE, WHICH SERVES THE MUSCLES & SKIN OF THE SHOULDER, HAS THE MOST LIMITED DISTRIBUTION. THE LARGE RADIAL NERVE PASSES DOWN THE POSTEROLATERAL SURFACE OF THE ARM AND FOREARM, SUPPLYING ALL THE EXTENSOR MUSCLES OF THE ARM, FOREARM & HARD AND THE SKIN ALONG ITS COURSE. MEDIAN NERVE: SUPPLY MOST OF THE FLEXOR MUSCLES IN THE FOREARM AND SEVERAL MUSCLES IN THE HAND. MUSCULOCUTANEOUS: ARM MUSCLES THAT FLEX THE FOREARM AND THE SKIN OF THE LATERAL SURFACE OF THE FOREARM.
ULNAR NERVE: TRAVELS DOWN THE POSTEROMEDIAL SURFACE OF THE ARM. (FUNNY BONE)
LUMBAR PLEXUS
ARISES FROM VENTRAL RAMI OF L1-L4 & SOMTIMES T12. ITS NERVES SERVE THE LOWER ABDOMINOPELVIC REGION AND THE ANTERIOR THIGH. THE LARGEST NERVE IS THE FEMORAL NERVE.
SACREL PLEXUS
ARISING FROM L4-S4, THE NERVES SUPPLY THE BUTTOCK, POSTERIOR SURFACE OF THE THIGH AND VIRTUALLY ALL SENSORY & MOTOR FIBERS OF THE LEG & FOOT. THE MAJOR NERVE IS THE SCIATIC NERVE, THE LARGEST NERVE IN THE BODY.
SOMATIC REFLEXES
INCLUDE ALL THOSE REFLEXES THAT INVOLVE STIMULATION OF SKELETAL MUSCLES BY THE SOMATIC DIVISION OF THE NS. AN EX: IS THE RAPID WITHDRAWL OF A HAND FROM A HOT OBJECT.
AUTONOMIC REFLEXES
AKA: VISCERAL REFLEXES. ARE MEDIATED THROUGH THE AUTONOMIC NS, AND WE ARE NT USUALLY AWARE OF THEM. THESE RELFEXES ACTIVATE SMOOTH MUSCLES, CARDIAC MUSCLE, AND THE GLANDS OF THE BODY, AND THEY REGUALTE BODY FUNCTIONS SUCH AS DIGESTIONS, ELIMATINATION, BLOOD PRESSURE, AND SALIVATION & SWEATING.
EXTEROCEPTORS
REACT TO STIMULI IN THE EXTERNAL ENVIROMENT, AND TYPICALLY THEY ARE FOUND CLOSE TO THE BODY SURFACE.
INTEROCEPTORS
RESPOND TO STIMULI ARISING W/ IN THEBODY.
(CHEMORECEPTORS)
PROPRIOCEPTORS
LIKE INTEROCEPTORS, RESPOND TO INTERAL STIMULI BUT ARE RESTRICTED TO SKELETAL MUSCLES, TENDONS JOINTS, LIGAMENTS, AND CONNECTIVE TISSUE COVERINGS OF BONES AND MUSCLES. THEY PROVIDE INFO ON THE POSITION AND DEGREE OF STRETCH OF THOSE STRUCTURES.
GENERAL SENSORY RECEPTOR
CUTANEOUS RECEPTORS & PROPRIOCEPTORS
SPECIAL SENSES
INCLUDE: SIGHT, HEARING, EQUILIBRIUM, SMELL & TASTE.
GENERAL SENSES
REACT TO TOUCH, PRESSURE, PAIN, HEAT, COLD, STRETCH, VIBRATION, AND CHANGE IN POSITION AND ARE DISTRIBUTED THROUGHOUT THE BODY.
OLFACTORY EPITHELIUM
(ORGANS OF SMELL) OCCUPIES AN AREAS OF ABOUT 5CM2 IN THE ROOF OF THE NASAL CAVITY. SINCE THE AIR ENTERING THE HUMAN NASAL CAITY MUST MAKE A HAIRPIN TURN TO ENTER THE RESPITORY PASSAGES BELOW, THE NASAL EPITHELIUM IS IN THE RATHER POOR POSITION FOR PERFOMING ITS FUNCTION. THIS IS WHY SNIFFING INTESTIFIES THE SENSE OF SMELL.
*CHEMORECEPTORS*
SURROUNDED BY SUPPORTING CELLS. THE OLFACTORY RECEPTOR CELLS ARE BIPOLAR NEURONS WHOSE OLFACTORY CILIA EXTEND OUTWARD FROM THE EPITHELIUM. AXONAL NERVE FILAMENTS EMERGING FROM THEIR BASAL ENDS PENETRATE THE CRIBRIFORM PLATE OF THE ETHMOID BONE & PROCEED AS THE OLFACTORY NERVES TO SYNAPSE IN THE OLFACTORY BULBS LYING ON EITHER SIDE OF THE CRISTA GALLI OF THE ETHMOID BONE. IMPULSES FROM NEURONS OF THE OLFACTORY BULBS ARE THE CONVEYED TO THE OLFACTORY PORTION OF THE CORTEXT W/ OUT SYNAPSING IN THE THALMUS.
TASTE BUDS
SPECIFIC RECEPTORS FOR THE SENSE OF TASTE, ARE WIDELY BUT NO UNIFORMLY DISTRIBUTED IN THE ORAL CAVITY. MOST ARE LOCATED IN PAPILLAE, ON THE DORSAL SURFACE OF THE TONGUE. A FEW ARE FOUND ON THE SOFT PALATE, EPIGLOTTIS, PHARYNX AND INNER SURFACE OF THE CHEEKS. TASTE BUDS ARE LOCATED PRIMARILY ON THE SIDES OF THE LARGE ROUND CIRCUMVALLATE PAPILLAE IN THE SIDE OF THE WALLS OF TEH FOLIATE PAPILLAE AND ON THE TOPS OF THE MORE NUMEROUS MUSHROOM SHAPED FUNGIFORM PAPILLAE. EACH BUD CONSISTS OF 2 TYPES OF MODIFIED EPITHEAL CELLS: GUSTATORY OR TASTE CELLS & BASAL CELLS . SEVERAL NERVE FIBERS ENTER EACH TASTE BUD AND SUPPLY SENSORY NERVE ENDINGS TO EACH OF THE TASTE CELLS. THE LONG MICROVILLI OF THE RECEPTOR CELLS PENETRATE THE EPITHEAL SURFACE THROUGH AN OPENING CALLED THE TASTE PORE. WHEN THESE MICROVILLI CALLED GUSTAOTRY HAIRS CONTACT SPECIFIC CHEMICALS IN THE SOLUTION, THE TASTE CELL DEPOLOARIZE. THE AFFERENT FIBERS FROM THE TASTE BUDS TO THE SENSORY CORTEX IN THE POSTCENTRAL GYRUS OF THE BRAIN ARE CARRIED IN 3 CRANIAL NERVES: FACIAL NERVE, SOPHARYNGEAL NERVE & THE VAGUS NERVE.
*SOUR SWEET, BITTER, SALTY, AND UMAMI*
THYROID GLAND
COMPOSED OF 2 LOBES JOINED BY A CENTRAL MASS. IT IS LOCATED IN THE THROAT. IT PRODUCES 2 MAJOR HORMONES: THYROID HORMONE & CALCITONIN.
PARATHYROID GLANDS
ARE FOUND EMBEDDED IN THE POSETIOR SURFACE OF THE THYROID GLAND. TYPICALLY THERE ARE 2 SMALL OVAL GLANDS ON EACH LOBE, BUT THERE ARE MANY MORE & SOME MAY BE LOCATED IN OTHER REGIONS OF THE NECK. THEY SECRETE PARATHYROID HORMONE, THE MOST IMPORTANT REGULATOR OF CALCIUM BALANCE OF THE BLOOD.
ADRENAL GLANDS
LOCATED ATOP THE KIDNEYS. THE ADRENAL MEDULLA DEVELOPS FROM NEURAL CREST TISSUE AND IT IS DIRECTLY CONTROLLED BY THE SNS. RESPOND TO THIS STIMULATION BY RELEASING EPINEPHRINE AND NONREPINEPHRINE WHICH ACT IN CONJUNCTION W/ THE FIGHT OR FLIGHT RESPONSE.
PANCREAS
LOCATED BEHIND THE STOMACH, FUNCTIONS AS BOTH AN ENDOCRINE & EXOCRINE GLAND. IT PRODUCES DIGESTIVE ENZYMES AS WELL AS INSULIN AND GLUCAGON, IMPORTANT HORMONES CONCERNED WITH THE REGULATION OF BLOOD SUGAR LEVELS.
THE GONADS
PRODUCES FEMALE SEX CELLS, THE OVARIES PRODUCE 2 STEROID HORMONE GROUPS, THE ESTROGENS & THE PROGESTERONE. DO NOT BEGIN UNTIL THE ONSET OF PUBERTY.
THE PAIRED OVAL TESTES OF THE MALE ARE SUSPENEDED INA POUCHLIKE SAC, OUTSIDE THE PELVIC CAVITY. IN ADDITION TO THE MALE SEX CELLS, SPERM, THE TESTES PRODUCE THE MALE SEX HORMONE TESTOSTERONE.
THYMUS
LOCATED IN THE SUPERIOR THORAX. IT BEGINS TO ATROPHY AT PUBERTY AND BY OLD AGE IT IS RELATIVELY INCONSPICUOUS. THE THYMUS PRODUCES HORMONES CALLED THYMOSIN & THYMOPOITIN WHICH HELP DIRECT THE MATURATION & SPECIALIZATION OF A UNIQUE POPULATION OF WHITE BLOOD CELLS CALLED T LYMPHOCYTES OR T CELLS.
PINEAL GLAND
LOCATED IN THE ROOF OF THE 3RD VENTRICLE OF THE BRAIN. ITS MAJOR ENDOCRINE PRODCUT IS MELATONIN.