Anatomy Chapter Notes
Anatomy Chapter Notes
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Popular in Anatomy
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All-or-None Principle You can have… - A stimulus causing a slight polarization - Stimulus that is enough to cross the threshold and open channels to get further depolarization that’ll right itself - You can have a stimulus that is larger than your threshold, but the way action potential looks never changes - Doesn’t matter how far above threshold stimulus gets: it’s either gonna fire or its not; it wont fire bigger or longer if you go above threshold Anatomy Lecture Notes Exam 3 Diencephalon(15.15) o Thalamus Not part of the cerebral nuclei Half in the right, and half in the left hemispheres Relay center for all sensory impulses except smell Thalamus directs the impulses to the appropriate locations in the right or left parietal lobes or the occipital lobes or the temporal lobes Initiates physiological shock o Hypothalamus Inferior and Anterior to the thalamus Small area of the brain Does a multitude of different things Monitors your blood stream Knows whats going on in all parts of your body Communicates with the nervous system and endocrine system Master control of the Endocrine system Control of emotional behavior Sex drive Control of food and water intake Regulation of sleep-wake (circadian rhythms) o Epithalamus Control center of emotional and visceral response to odors o Pineal gland Melatonin production 1 Anatomy Lecture Notes Exam 3 Informs your brain of the photo period When it gets dark the Melatonin is released o Mammillary Bodies Centers for small reflexes and swallowing Sniffing Reflex Only 2 to 4 percent of air gets high enough to stimulate olfactory receptors o Brain stem Everything inferior to the Diencephalon Mesencephalon(table 15.1) o Brainstem o Contains cranial nerve nuclei for CN III-IV o Tectal plate(15.8) Cerebral peduncle Projection fibers that carry impulses form the lower parts of the brain to high parts and vise versa Superior colliculi Responsible for eye hand coordination interior colliculi Auditory reflexes o Controls vibrations in response to the intensity of the atmospheric sound waves o Tympanic membrane o Substantia nigra Dark color because of the unusually high density of melanin Neurons produce dopamine(neurotransmitter)* Parkinsons disease* When the neurons in this structure do not produce enough dopamine, they have trouble initiating movement Causes tremors, particularly in arms Abnormal gait By the time symptoms occur, about 70% of neurons in substantia nigra are already dead. o Great reserve capacity of the brain 2 Anatomy Lecture Notes Exam 3 o Other examples: The heart can beat up to 200BPM, sustained for a short time to escape a life-threatening situation. Respiratory rate doubles; Urinary bladder can hold up to 1000mL, but urge is felt at about 150mL. o About 35% of the neurons are used on a typical day. Smooth out motor impulses that have come through the cerebral nuclei. Treating Parkinson’s with dopamine is ineffective, because it cannot pass the blood-brain barrier Treatment involves Administering L-DOPA o Precursor to Dopamine o L-Dopa is only a temporary therapy and becomes less effective over time because fewer neurons are present General role of dopamine: Premotor cortex selects muscles, precentral gyrus initiates impulses, impulses pass through cerebral nuclei, and then substantia nigra Substantia nigra smoothes/blends the impulses. o Red nuclei Looks red because of high iron deposition Equilibrium mechanism Posture reflex Equilibrium process found in the inner ear Muscles fluctuate on each side of the body to maintain balance. o Reticular formation(17.14) Runs span of brain stem Involved in arousal*: waking you up and keeping you conscious 3 Anatomy Lecture Notes Exam 3 Keeps your brain aroused so that you can respond to stimuli Metabolic state Keeps you awake and a certain level of attentiveness Run from the medulla, through the pons and midsections, and to all parts of the brain Responsible for brain arousal Keeping the brain at a level of neurological activity where it can be stimulated. Various degrees of brain arousal o Deep sleep=reticular formations functioning poorly; Sleep suppresses reticular formations, however an external stimulus still awakens o Reticular Formations are functioning well about 30min after waking up in the morning o At the prime of our day, they are functioning at their peak. Varies for each person. In a coma, reticular formations are nonfunctional. Coma does not mean that you are neurologically dead; other sensory mechanisms may be working. Memory from during the coma can be perfect. Metencephalon o Pons(15.20) Integration center& helps with respiration -Connected to Cerebellar penducles: they pass through pons Relay center for impulses going to/from superior parts of the brain. Projection tracts Contains cranial nerve nuclei for CN V-VII(15.24) A nucleus is a aggregation of neuron cell bodies within the CNS Ganglion—An aggregation of neuron cell bodies outside the CNS(within PNS). o Cerebellum Motor coordination 4 Anatomy Lecture Notes Exam 3 Coordinates skeletal muscle impulse(i.e. walking) Stores memory of previously learned motor movements habits(i.e. riding a bike) Adjusts muscle activity to maintain posture—posture reflex. Knows the position of every part of the body, relative to the rest of the body, particularly the limbs Receives information from Proprioceptors: Three different groups Found in synovial joints, tendons of skeletal muscle, within skeletal muscles. Example: Placing hands where you cant see them, such as putting on a hook-from-behind bra. o Medulla Oblongata Relay center for impulses going from the spinal cord to the brain, and vice versa. Decussation: Area of crossing Contains nuclei for CN IX-CN XII Completely sensory cranial nerves do not originate within the CNS Location of the majority of decussation. Center for autonomic nuclei, which regulate the following functions: Heart rate and strength of contraction o As heart rate increases, so does the strength of contraction(more blood pumped per beat) Blood Pressure Respiratory Rate Coughing Sneezing Swallowing Vomiting Reflex(after visiting the local watering hole) Possibly urination and defecation. Injury to the medulla is bad. Functions executed by the brainstem structures: 5 Anatomy Lecture Notes Exam 3 o Controls vital functions to keep us alive o Sticking gun in mouth: hits brain stem directly o Vagus: viscera: autonomic functions o o On old olymus’ towering tops a fine Viennese girl viewed a hawk o HOW MANY CRANIAL NERVES INNERVATE THE EYE (BOTH MOTOR AND SENSORY ASPECTS)? o WHICH ONES ARE THEY? HOW MANY ARE MOTOR AND HOW MANY SENSORY Limbic System(15.23) Emotional brain or “lizard brain” Hippocampus: memory formation Amygdala: emotions& emotional encoding of memory Especially in fear Includes telencephalon and diencephalon Also memory processing and long-term memory Ch 16—The Spinal Cord (16.1) The spinal cord begins in the foramen magna, at the medulla oblongata. Spine is divided into regions: o Cervical(C1-C8) o Thoracic(T1-T12) 12 segments. No plexus in the thoracic region o Lumbar(L1-L5) Lumbosacral Enlargement 6 Anatomy Lecture Notes Exam 3 Lumbar, Sacral, and Coccygeal portions Tracts that make up the spinal cord start to peel apart when they reach the lumbar region Cauda Equina Horse Tail Portion of the spine that is Inferior to the L1 vertebrae. Spinal nerves come off the bottoms of the segments Lumbar Plexus Plexus: Grouping of nerves after they exit the spinal cords on left& right side Connections between adjacent spinal nerves Connecting adjacent spinal nerves, results in each spinal nerve overlapping the parts of the body they serve. o Less neurological damage after an injury. o Sacral- innervates leg o Coccygeal o Whats A horn? Gray Matter o Whats a column? Fenunculus: White matter o Where does sensory info come in? posterior gray matter ; synapse in posterior horn; somatic information comes in through most posterior of posterior horn; visceral comes in through posterior but more anterior o Where does motor info go out? Anterior o Autonomic Motor: comes out of lateral horn The spine ends at L1(naval) Is only 16-18 inches long. Spinal cord is heavily vascularized Spinal Nerves are all mixed nerves o When we were talking about cranial nerves, some were all sensory, some were all motor, some were a mix Spinal cord is segmented 7 Anatomy Lecture Notes Exam 3 o Each Segment gives rise to a pair of spinal nerves. o The spinal nerves come off the lateral parts of the segments. o 8 segments in the cervical vertebrae The first 2 nerves come off before C1 The spinal cord passes through the vertebral column via the vertebral foramen. Intervertebral foramen—spinal nerves exit the spine to the body wall. Anterior view of the spine(16.2) o Spine is highly vascularized o Spinal nerves exit the lateral sides. o Meninges Dura mater Arachnoid mater Subarachnoid space Contains CSF Pia Mater Contains highly vascularized blood Blood-brain barrier. o Epidural Space Space between the meninges and the bone. Contains adipose tissue for protection of the spine from the bone. o Internal gray mater.(H-Pattern) o Anterior median fissure Deep Sulcus into the spinal cord Spinal nerves are fixed and will not move. These fissures allow for the formation of a space when the body is moved. 8 Anatomy Lecture Notes Exam 3 Increases surface area. Mobility o The spine is highly vascularized—veins enter the pia mater o Gray matter is internal—H pattern o White matter o Posterior median fissure (sulcus) Goes about 2/3 into the spinal cord, almost divides the spinal cord into two Deeper than anterior median fissure. Greatly increases surface area Nature intends surface area to be maxed out Increases mobility The spinal cord is basically severed by these sulci o Enables you to swivel and twist your body o The grooves open up when you twist (widen) o The spinal cord cannot move into the muscle so this allows movement to occur The spinal nerves that go out into the body wall are fixed in their location and cannot slide deeper or pull back into the muscles Allows the spinal nerves to stay in their respective locations and movement to occur o Spinal Nerves Divides into two roots: Anterior and posterior Posterior Root Ganglion—Enlargement on the posterior root; Sensory neuron cell bodies. Ganglion=cell bodies are sensory Posterior Root—Contains dendrites of sensory neurons All spinal nerves are mixed nerves: both sensory and motor. Anterior Root—Contains axons of motor neurons 9 Anatomy Lecture Notes Exam 3 Rootlets—posterior and anterior roots are made of rootlets. Allow each spinal nerve to be in contact with the entire segment(inferior-superior) Lumbar Puncture/Epidural o Epidural—Injection of a pain suppressor in process of giving birth. o Administered Bent over or in fetal position to increase curvature of the vertebral column o Numbs the sensory neurons , but motor neurons not affected o Motor control maintained o Needle inserted between L3-L4 or L4-L5 in the cauda equina area. o Complications are rare. Spinal Cord(16.3) Looks like a butterfly o White Matter Myelin tracts Regionalized into faniculi Posterior, Lateral, and Anterior Faniculus. o Grey Matter* Cell bodies Info coming into posterior route has to be sensory: In spinal cord Motor information comes out anterior : out of spinal cord Divided into horns (H) Posterior, Lateral, and Anterior Horns Lateral and Anterior Horns are together o This section is wider Anterior Horn Lateral Horn Gray commissure o Connection in the “H” o Interneurons cross from one side of the CNS to the other LABEL WHICH IS SENSORY, MOTOR, MIXED IN BRAIN, WHERE DO U FIND SPINAL FLUID? Between arachnoid matter and piomatter 10 Anatomy Lecture Notes Exam 3 Subarachnoid space: find cerebrospinal fluid IF INSERTING NEEDLE, INSERT IN SUBARACHNOID SPACE Theres a space called the epidural space Women in labor: insert needle in epidural space to numb o Skin, hypodermis(subcutaneous layer), back muscles, fibrocartilage, intervertebral disc, to subarachnoid space o Don’t wanna damage spinal cord o Cotta aquina: lumbar has more space to stick needle o Patient can curl into ball Cross Section of the Spinal Cord(Figure 16.4) o Shows the function in the different areas of the spinal cord o Somatic sensory neuron Body wall and skeletal muscle. Unipolar neuron cell Nerve cell body is in the posterior root ganglion Somatic sensory neurons end in the posterior horn of the gray matter of the spinal cord Goes into the posterior root ganglion, and then the posterior horn Dendrites cover a very small area of the somatic area, thus a large amount of neurons are present in the area. 11 Anatomy Lecture Notes Exam 3 Sensory nerve enters the posterior root and the axon continues into the spinal cord and ends in the posterior horn Interneuron synapses with dendrites motor neurons Go from the posterior horn to the anterior horn o Will connect with motor neurons in the anterior horn (to muscles) and out the anterior root to respond to impulse Dendrite Nerve Cell Bodies Axon Two interneurons receive impulses o One travels anteriorly to the motor neurons o The other travels to the white matter and takes impulses to the brain o Visceral sensory neuron Pick up impulse from internal organ Ie. Pain in the chest, hungry feeling, cramping Goes into the posterior root ganglion, and then the posterior horn From organ or tissue to spinal nerve to the spinal cord Dark blue area of the posterior is where they synapse with autonomic motor neurons in the lateral horn Ends deeper in the posterior horn Takes impulses to autonomic motor neurons o Autonomic Motor Neurons Originate in anterior horn Autonomic—Part of the nervous system that controls the internal organs. Exit via the anterior root, then branch to the organs. o Somatic Motor Neurons Originate in lateral horn o Sensory neurons end in the posterior horn o Posterior Horn 12 Anatomy Lecture Notes Exam 3 Beginnings of both Visceral and Somatic Sensory Neurons. Receive senses from the visceral organs in the anterior ¼ of the posterior horn The posterior 3/4of the posterior horn receives impulses from somatic sensory neurons o Anterior Horn Contains dendrites, cell bodies, and beginnings of axons of somatic motor neurons Beginning of somatic motor neurons o Lateral Horn Beginning of autonomic motor neurons o Interneurons Connect Posterior and Lateral/Anterior horns Anatomy of the Spinal Nerves (Figure 16.5) o Rami/Ramus Branch of a spinal nerve going to the body wall o Anterior and Posterior Ramus Basically synonymous with the spinal nerve o Posterior Ramus Serves muscles of the back o Rami Communicates o Anterior Ramus(16.7) The spinal nerve runs parallel with the ribs and the branches branch off into almost all tissue that you have Branches run to internal organs and the body wall There are also sensory neurons coming into the anterior ramus o Dermatomes Segment of skin that is affected by a particular part of the spinal nerve Reflexes 13 Anatomy Lecture Notes Exam 3 o Reflexes are Rapid, automatic, involuntary reactions of muscles or glands to a stimulus o An automatic, sudden, involuntary response to a stimulus o When the integration takes place in the spinal cord, the refle is a spinal reflex o Not conscious of the action o Involuntary response with no intent or pre-awareness of the reflex activity o Allows you to move the affected part of the body away from the potentially life-threatening stimulus. o Reflex Arc (16.12) The stimulus depolarizes the sensory neuron When the membrane becomes permeable to the sodium ions for outside the cell from a stimulus the impulse is created Nerve impulse travels with the sensory neurons to the spinal cord, nerve impulse is processed within the spinal cord from the posterior to the anterior horn anterior root spinal nerve muscle The interneuron takes the impulse from the sensory neuron in the posterior horn to the motor neuron in the anterior horn, out the spinal nerve, and then the ramus, then the effector(muscle) Immediately moves the part away from the stimulus. Then the motor neuron transmits the impulse to effectors Different kinds of impulses(16.13) Monosynaptic reflex o No interneuron o Sensory neuron communicates directly with the motor neuron that stimulates the response o Knee Jerk Reflex--When hit with a mallet on the knee The area of aim is the fat pad below the patellar ligament If you tap on the tendon the automatic response is to contract 14 Anatomy Lecture Notes Exam 3 Dense regular connective tissue o Collagen fibers o No elasticity Ligament is distorted into the fat pad o Whatever its attached to has to move Tibia and patella(smaller) The patella is going to move Then will move tendons pulls on the quadriceps muscle Tighten up proprioceptors o Proprioceptors monitor amount of overlap of the myofilaments in the muscles. o Proprioceptors depolarize, impulse sent to the sensory neuron, through spinal nerve, posterior root, anterior horn, motor neuron, to the quadriceps muscle o Impulse is initiated in the muscle and effect is initiated in the muscle. o Stimulates only the quadriceps muscle to regain overlap o This reflex aims to maintain the overlap in the quadriceps muscle fibers. o In muscles, tendons and synovial joints 15 Anatomy Lecture Notes Exam 3 o Stimulated receptors in one location in the quadriceps muscle o Proprioceptors—Sensory Neuron—posterior horn— autonomic motor neuron— effector organ. This is not the same neurological impulse at the feeling of the mallet. Polysynaptic reflex (withdrawal) o Move your body from the stimulus ASAP o When do you become aware or conscious of this burn? After withdrawal ( impulse goes straight to motor neuron) o Respond by sending impulses to various muscles o Utilizes an interneuron for communication between sensory and motor neurons KNOW WHEN * CONSCIOUS OF KNEE JERK/ WITHDRAWAL Gray Matter o Unmylienated axon and dendrites o Mylienated axons of interneurons White Matter o Mylienated axons o Organized into bundles or tracts of sensory of interneurons (AXONS) carrying sensory and motor impulses to and from the brain Sensory pathways in the spinal cord o Bundles and tracts of interneuron that are carrying sensory impulses up to the brain 16 Anatomy Lecture Notes Exam 3 Step on a tack with bare feet (left foot)Tack punctured foot Depolarizes receptors(Modified the membrane of the neuron and you get an impulse) travels to the spinal cord via sensory neuron, a unipolar neuron(about 3ft long) interacts (synapses) with two interneurons simultaneously, an interneuron carries the impulse to the motor neuron: o Motor neuron goes out anterior root, to the spinal nerve, out through the body wall, out rami, to the hip, thigh, etc o moves muscles in the hip and leg to pick up the foot. The other interneuron(short one) goes out into the white matter on its way to the brain (right side of the brain): o This is happening as the reflex is happening o White matter contains tracts/bundles(17.1) Tracts are bundles of interneurons that run from the same part of the body to the same part of the brain. o When you get to the superior end of the spinal cord: Enters the medulla, and decussation occurs(impulses transferred to the right hemisphere of the brain. Synapses with another interneuron Decussation results in impulse going to the RIGHT side of the brain. Carries the impulse through the pons Then through the midbrain (mesencephalon) through pedicles Through the thalamus(15.12) Synapses with another interneuron Takes the impulse to superior portion of the longitudinal sulcus in the primary somatosensory complex (POST CENTRAL GYRUS) o The superior portion of the longitudinal sulcus. Then to the parietal somatosensory association area o Interprets something is stuck in your foot Impulse must go back to the left side in order to speak via the commissural tract across the corpus colosum to Wernike’s Area 17 Anatomy Lecture Notes Exam 3 Gnostic area choose the words in the order you want to put them in Goes to the prefrontal cortex through the articulate fasciculus o Decides if you want to say it or not To the Broca’s Area o Selects the muscles you need to speak the words you chose in the order you chose o Premotor Cortex PreCentral Gyrus o Initiates impulses Goes to the primary motor cortex o Initiates the neurons to express the words you chose These impulses to through the cerebral nuclei o Unconscious control of the skeletal muscles The impulses are then smoothed out in the substania nigra o Midbrain Pons Cerebellum (coordinates them to put them in the right sequence) Pons Medulla Cranial Nerves 5, 7, 10, 12 Every new destination involves a synapse with a different interneuron o To look at the tack in the foot Strengthen the muscles in the right leg, bend the left leg, bend the torso, move the neck, move your eyes, move your arms, and bend fingers, moving your arms Right somatosensory association area anterior to the right prefrontal cortex (your brain decides the response it has to make about what this stimulus is and what you need to do about it) 18 Anatomy Lecture Notes Exam 3 Right prefrontal cortex decides to use both sides of your body (so you send impulses to the right premotor cortex) and then you send other impulses to the left premotor cortex to decide what muscles you need via commensural fibers and the corpus callosum(bc you need to stiffen right leg, move right arm, etc) precentral gyrus of the respective side(initiates impulses) Arms move, legs move, body wall tightens cerebral nuclei substania nigra(some) red nuclei(some)(helps to maintain equilibrium) midbrain pons cerebellum (some go back to the pons to enter cranial nerves 6) and (some go to the midbrain for cranial nerves 3, 4) in order to move your eyes whereas some go into the medulla for cranial nerves 11 (to help bend your neck) Then the impulses get decussated in the medulla and they synapse with interneurons to go down the spinal cord in tracts neurons have several axon branches and carry the impulses down some of the impulses go out of the axons into the biracial plexuses (goes to the arms and fingers) meanwhile the impulses continue down the cord and they go out into the thoracic area so you can bend your back forward and backwards out the lumber and sacral plexus into your hips and legs Figure 15.12 Proprioceptors: Tell your body where something is occurring 19 Anatomy Lecture Notes Exam 3 Ch. 18—Autonomic Nervous System Autonomic Nervous system AUTONOMIC MOTOR OUTPUT ONLY; NOT INPUT (NOT VISCERAL SENSORY) o Fight or flight mechanism Run as fast as you can for as long as you have to o The autonomic nervous system is what maintains and then returns you to homeostasis o Homeostasis—Chemical equilibrium o Control of the muscles that operate your internal organs o Totally involuntary, no conscious control of these nerves o Maintains or returns to homeostasis in response to changing environmental conditions Internal, chemical equilibrium within your body o Stimulus sends a sensory impulse into the sensory nervous system(just as in somatic), but motor impulse is delivered to the effector by TWO neurons. One leaves the lateral horn, out anterior root, into spinal nerve to the body, into the ganglion, synapses with a second motor neuron, which takes the impulse to the effector Pre-ganglionic Motor Neuron—The motor neuron that leaves the CNS Ganglion—A collection of cell bodies outside of the CNS. Ganglionic Autonomic Motor Neuron—(Post-Ganglionic) Neuron where its dendrites and cell bodies are in a ganglion somewhere, and the axon takes the impulse to the effector It takes one motor neuron to take a somatic impulse from the CNS to the effector, but the autonomic nervous system takes two motor neurons, one taking out of the CNS to a ganglion, a second from the ganglion to the effector. o Two divisions Sympathetic Gears you up Parasympathetic 20 Anatomy Lecture Notes Exam 3 Slows you down Returning back to normal o Sympathetic Division “Fight or Flight” In order to run from dogs’ you need excess O2 In order for the increase of O2 to get to the skeletal muscle your heart rate increases (blood pressure increases) Heart rate can increase to 200BPM Produce adrenaline—A hormone produced by the adrenal medulla that helps the nervous system make these adjustments in the body Increase respiratory rate to support skeletal muscles(doubles) Contract the spleen to release more red blood cells(carries oxygen) o Spleen is along the left abdominal wall, behind the stomach Dilate pupils(CN III) o More light to see better Increase metabolic rate o Glycohydrolysis—Breakdown of glycogen reserves o After the breakdown of glycogen is complete, lipids are broken down as energy storage o Relax the muscles in the bladder so it can expand since you have excess metabolic waste that is expelled through the urine o Perspiration removes excess heat You shut down your digestive system in order to conserve energy for running(escaping the preverbal pack of pit bulls) o Blood flow is reduced to the large intestine, small intestine, and stomach. Saliva 21 Anatomy Lecture Notes Exam 3 o Change the chemistry of your saliva to become more viscous Don’t need saliva for digestion Clings to oral cavity so it doesn’t dry out due to increased respiration Moist cavity Helps to vocalize cries for help. o Perception of salvia: Fluid material Keeps oral cavity moist Keeps clean (anti-bacterial compounds) Reproductive System o Body will also shut down the reproductive systems o Female: Shut down if not pregnant Reduces odiferous molecule production(leaves a scent trail) If pregnant, uterus will contract causing labor/abortion Fetus is expelled to create a diversion Due to the scent of the fetus o Male: May ejaculate to leave attractant Ejaculation will occur without erection of the penis. Sympathetic nervous system increases your odds to survive an emergency situation. o Parasympathetic Division You can’t return to normalsy in a few seconds, it will take longer (possibly a few hours) Heart rate will rapidly drop to 160, then slow down gradually over a period of 3 hours. Respiration rate may take a few minutes to return to normal 22 Anatomy Lecture Notes Exam 3 The cause for the delay for respiration and heart rates to return to normal is because more metabolic wastes were produced during the fight or flight situation. Crying Part of the parasympathetic division (not sympathetic) Relieves emotional stress Help you return to normalsy faster Reproductive System Females: Vaginal contractions will start up making mucus Males: will have an erection due to increased blood flow to the abdominal area to restart the digestive system. Digestive System Will Start up Blood vessels dilate o Side effect can be an erection because of the blood that is sent to the digestive system. Red blood cells go back in to the spleen o The autonomic system contains a neuron that goes to an autonomic ganglion and then synapses with a bunch of neurons that send impulses throughout the body o Preganglionic autonomic motor neuron ganglion postganglionic autonomic motor neuron Sends impulses to smooth muscle, cardiac muscle, and glands (ducts) Visceral Nervous System Ganglions distribute impulse (distribution networks) Preganglionic axon begins in the lateral horn of the CNS Figure 18.6: Sympathetic Division o Impulse Distribution Networks o Preganglionic Sympathetic Motor Neurons o Postganglionic Sympathetic Motor Neurons o Originates in the spinal cord from segments T1-L2 23 Anatomy Lecture Notes Exam 3 On each side of the spinal cord are chains of “popped beads” Called the sympathetic trunk On each side of the spinal cord(outside the vertebral column) there are two structures called a Sympathetic Trunk, which is a ganglion adjacent to a spinal nerves. Each represents a ganglion part of the trunk (Collection of Nerve Cell Bodies outside the nervous system) Some are inferior to L2 and some are superior to T1 o Rami Communicantes Sympathetic trunk ganglion comes off of this One on each side of the spinal cord o Peripheral Ganglia Out in the body other than the sympathetic trunk (Prevertebral Ganglia) o Nerve Impulse Distribution Network—Sends impulses to many different places at the same time: Exit spinal cord in preganglionic neurons Gangli in sympathetic trunk Goes up the trunk Synapse with post ganglionic neurons Carries impulses to the eyes, salivary glands, heart, and lungs. Farther down the sympathetic trunk(T5-T9), preganglionic neurons go to the peripheral gangli(prevertebral gangli) Preganglionic neurons synapse with postganglionic neurons which go to the abdominal organs. Still further down the spinal cord, T10-T12 preganglionic neurons go to a different peripheral ganglion, which the postganglionic neurons go lower down the abdominal cavity to large and small intestines In L1-L2 area and below, premotors go to another peripheral ganglion taking impulse to the bladder and reproductive organs. 24 Anatomy Lecture Notes Exam 3 In some cases preganglionic neurons come out of the spinal cord and go up the trunk and others go down, and some go straight through, carrying impulses to initiate the sympathetic response. All preganglionic motor neurons go to a ganglion and synapse with a postganglionic neuron EXCEPT those that go to the adrenal gland(adrenal medulla) Produces adrenaline/epinephrine No synapse because it takes more time Adrenaline supplements the nervous system o To activate impulses: Prefrontal Lobe (decide what to do) Premotor cortex (decide on muscles to use) Precentral gyrus (initiate impulses to muscles) Cerebral Nuclei Substania Nigra (smooths out impulses) Red Nuclei (Equilibrium) Midbrain Pons Cerebellum (puts impulses in order) Some will go back to Pons to activate Eyeballs Medulla (Decussate) Go down tract (interneurons in the white matter) Synapse with neurons in the gray matter Go out into lateral horn in particular segment Synapses with the autonomic motor neurons and sometimes with short interneurons Goes down the Rami communicantes into the neighboring sympathetic nerve cells bodies in the ganglion o More RBC (More O ) 2 Sympathetic Response Contract smooth muscles of the spleen to squeeze out stored RBC (Erythrocytes) because you sped up the respiratory system and the circulatory system. o Kidneys 25 Anatomy Lecture Notes Exam 3 Remove metabolic waste to urinate If you produce more waste you have to speed up the kidneys to remove more waste o Motor Impulses to Pancreas It produces enzymes you use for digestion Shut the digestive system down you darn well better shut this down The enzymes may produce holes in the intestines o You sweat to get rid of some metabolic waste since utilizing muscles creates heat and metabolic waste Blood vessels are dilated o Adrenal Glands (Adrenal Medulla) Direct connection with a PREganglionic neuron Faster synapse Figure 18.5: Parasympathetic Division o Nothing comparable to the sympathetic trunks o Originates from two distinct parts of the CNS: Brain and Sacral Region o In the brain in the Nuclei Gives rise to cranial nerves 3, 7, 9, 10 They have parasympathetic components. CNIII: Occumotor Nerve—Constriction of pupils(otherwise will burn out photoreceptors) CNVII: Facial Nerve—Increases secretion from lacrimal gland of eye, submandibular and sublingual salivary glands. Return saliva back to normal viscosity. CNIX: Increases secretion from parotid salivary gland. CNX: Slows heart rate and respiratory rate, starts digestive system, reproductive organs. Innervates smooth muscle and glands of heart, lungs, larynx, trachea, moist abdominal organs. o In the sacral region of the spinal column S2, S3, S4 Parasympathetic preganglionic neurons go out to the large intestine, bladder, penis, uterus, and vagina. 26 Anatomy Lecture Notes Exam 3 o Impulses come out of the parasympathetic division at different times(changes occur over a period of a few hours) o No peripheral gangli: The preganglionic go from the CNS to the effector organ where they synapse with short parasympathetic post ganglionic neurons—Called Terminal Gangli Terminal gangli are immediately adjacent to the organ. o Parasympathetic Preganglionic neurons Go out to the tissue that is to be stimulated (adjacent) Then they synapse with Parasympathetic postganglionic (very short) neurons Called terminal ganglia (different than the sympathetic division) Types of Senses for Different Stimuli: Tactile Receptors (Cuntaneous Receptors)(19.5) o Provide information on touch, temperature, pain, pressure o Most receptors are located in the Dermis layer o Tactile disc—Most superficial receptors sensitive strictly to touch. Fine touch senses(E.g. reading brail) In the Stratum Basale o Receptors must be depolarized They are a type of mechanoreceptors--depolarized by MECHANICAL distortion. Depolarized: The permeability of the receptors is altered (allowing the flow of Na into the cell initiating an impulse) o Receptors are for defense Types of Tactile Receptors(Table 19.2) o Tactile Receptors—Bags of dendritic ends for touch, pressure, etc. o Mechanoreceptor—A receptor that is stimulated by distortion Compression, squeezing, distortion Depolarized by pressure. The brain perceives the amount of pressure on a part of the body based on how many receptors are depolarized.(More, deeper receptors=greater pressure.) 27 Anatomy Lecture Notes Exam 3 o Tactile corpuscles Touch/Pressure Location Dermal papillae Papillary Layer Lips, Palms, Eyelids, Tongue, Nipples, Genitals Function Detects fine, light touch, and texture Stimulus Mechanoreceptors o Free Nerve Ending Location Widespread in deep epidermis and associated underlying connective tissue Most superficial receptors Reach the live areas of the epidermis Function Detects pressure, change in temperature, tissue damage, touch Stimulus Three different kinds; Mechanoreceptors, Thermoreceptors, Nociceptors. The mechanoreceptors are stimulated by very light touch because they are so close to the surface. Thermoreceptors: o Monitor both surface temperature and internal temperature. o Internal temp=98.6 degrees F o Surface temp<98.6 o Monitor temperature via monitoring the speed of molecules within the cytoplasm o Depolarized when molecules move at a certain speed Nociceptors o Pain receptors 28 Anatomy Lecture Notes Exam 3 o Most abundant pain receptors throughout the body, not just at the surface. o Pain represents cell damage or destruction o Cell membrane is compromised(leaks or destroyed) Molecules from within the cytoplasm leaks into the interstitial area Nerve endings are depolarized by the cytoplasmic molecules. o Root Hair Plexus Location Surrounds hair follicles in the dermis Function Detects movement of hair Maintain body temperature Detects wind, insects on the surface, protection from harmful creatures. If a bee lands on the body, it stimulates root hair plexuses, giving you a head start to prevent from getting stung. Stimulus When the hair moves, it changes the membrane of the plexus, allowing the sodium ions to pass through Mechanoreceptors o Tactile Disc Location Stratum basale of the epidermis Function Detects light touch, shapes, and textures Stimulus Mechanoreceptors o Krause bulb Location Dermis; mucous membranes of conjunctiva, lips, oral cavity, nasal cavity, vagina, and anal cavity Deeper in dermis Function 29 Anatomy Lecture Notes Exam 3 Detect light pressure and low frequency vibration Stimulus Mechanoreceptors o Lamellated Corpuscle Location Dermis, subq tissue, synovial membranes, some viscera Function Detect deep pressure and high frequency vibration Stimulus Mechanoreceptors o Ruffini corpuscle Location Dermis and subq layers Function Detects pressure and skin distortions Stimulus Mechanoreceptors Proprioceptors o Receptors in three types of tissue: Synovial joints—Tells the location of the joint Tendons—Monitor tension/resistance on the tendon; ensures necessary amount of overlap in the myofilaments(review muscle impulses) o In the muscles that monitor the stretch Stimulates sensory impulses to go to the CNS Stimulates “knee jerk reflex” o Found in tendons Monitors the amount of pull on a tendon o Sends the CNS an exact position of where your limbs are in your body If you get an itch, you can tell exact where it is Putting on a hook from behind bra o Cerebellum Stored memory (actions) Baroreceptor o “Stretch Receptors” o Monitor internal fluid pressure on the walls of vessels. 30 Anatomy Lecture Notes Exam 3 o Monitor pressure on the walls of the hollow internal structures o Monitoring the blood pressure on the artery walls o Pressure of urine on the bladder wall o Wall of rectum o Tell the brain how to react to the pressure inside the body Chemoreceptor o Depolarized by the presence of chemicals o Monitor the presence of molecules in the body o Olfaction(19.9) Clear up in the highest part of the nasal passage Monitors molecules in the air Many of which are odifferece Normal sense of smell Can distinguish 10,000 different odors Weakest sense o Gustatory Cells(19.6) Gustation--Taste Found on the sides of the papili on the surface of the tongue. Measure and analyze taste different from olfaction Depolarized by chemicals in the saliva o Removed from the food by saliva in process of chewing. Only 4 different modalities for taste: Salty, bitter, sweet, sour Omami—Sensory perception of proteins Perception of taste is the effect of each modality arriving in the insula lobe of the brain. Taste Buds(19.7) Contains gustatory cells Gustatory Microvilli—dendritic ends of the gustatory cells. Axons of the gustatory cells found feeding into the sensory nerve at the base Supporting Cell—Takes up space to ensure the gustatory cells remain elongated and the gustatory microvilli in contact with the surface of the oral cavity. o Blood chemistry is monitored continuously by chemoreceptors 31 Anatomy Lecture Notes Exam 3 The Eye(19.12) Cornea—outer covering of the eye Iris—Colored part of the eye surrounding the pupil Pupil—allows light to enter the eye Lens—refracts light rays to send to the posterior eye wall Eye Wall o Three Layers: Retina: Innermost layer Neurological layer Choroid Layer Highly vascularized Middle layer Sclera Outer layer White of the eye Fibrous connective tissue. Anterior Cavity: o Anterior Chamber Anterior of the iris. o Posterior Chamber Behind the iris, around the lens o Filled with aqueous matter Vitreous Chamber o Posterior to the lens o Filled with a gelatin like material called vitreous humor Photoreceptors(19.14) Light rays strike rods and cones The rods and cones depolarize and sends impulses back
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