Essentials of Human Anatomy Physiology Seventh Edition Chapter

Essentials of Human Anatomy & Physiology Seventh Edition Chapter 7 The Nervous System Central Nervous System, Drugs, the Brain and Neurotransmission Elaine N. Marieb This presentation contains copyright protected materials. Lecture Slides in Power. Point by Jerry L. Cook, edited by Melissa Scott Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Functions of the Nervous System · Sensory input – gathering information · To monitor changes occurring inside and outside the body · Changes = stimuli · Done by a sensory receptor (Ex. - Rods and cones of eye, olfactory neurons of nose, touch receptors in integument…) http: //www. colorado. edu/intphys/Class/IPHY 3430 -200/image/10 -4. jpg

Functions of the Nervous System · Integration · To process and interpret sensory input and decide if action is needed · Done in brain or spinal cords http: //www. faqs. org/health/images/uchr_02_img 0126. jpg

Functions of the Nervous System · Motor output · A response to integrated stimuli · The response activates muscles or glands (effectors)

Functional Properties of Nervous Tissue · Irritability – ability to respond to stimuli · Conductivity – ability to transmit an impulse Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings http: //media. photobucket. com/image/synapse 79/neuronen-m. Slide 7. 17 synapse. jpg#!o. ZZ 2 QQcurrent. ZZhttp%3 A%2 F%2 Fmedia. photobucket. com%2 Fimag e%2 Fpink_deity%2 FSynapse. jpg%3 Fo%3 D 2

Structural Classification of the Nervous System · Central nervous system (CNS) · Brain · Spinal cord · Peripheral nervous system (PNS) · Nerves outside the brain and spinal cord Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 2

Nervous Tissue: Support Cells (Neuroglia) · Nervous tissue does not regenerate well and has many “helper” cells to protect it and do various jobs. www. dmacc. edu/instructors/rbwollaston/Chapter_8_Nervous_System. htm Slide 7. 5

Nervous Tissue: Support Cells (Neuroglia) · Astrocytes · Abundant, star-shaped cells · Brace neurons · Form barrier between capillaries and neurons · Control the chemical environment of the brain Figure 7. 3 a Slide 7. 5

Nervous Tissue: Support Cells · Microglia · Spider-like phagocytes · Dispose of debris Slide 7. 6

Nervous Tissue: Support Cells · Ependymal cells · Line cavities of the brain and spinal cord · Have cilia that help to circulate cerebrospinal fluid Figure 7. 3 b, c Slide 7. 6

Nervous Tissue: Support Cells · Oligodendrocytes · Produce myelin sheath around nerve fibers in the central nervous system · The myelin sheath is a phospholipid “roll” that “insulates” the nerve fibers to increase the speed of conduction Slide 7. 7 a

Nervous Tissue: Support Cells · Satellite cells · Protect neuron cell bodies Figure 7. 3 e http: //kcfac. kilgore. cc. tx. us/mobleypageap 2/nerve%20 tisues/satellite%20 cells%204 orks%20 b. jpg Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 7 b

Nervous Tissue: Support Cells http: //legacy. owensboro. kctcs. edu/gcaplan/anat/images/Image 425. gif · Schwann cells · Form myelin sheath in the peripheral nervous system Figure 7. 3 e Slide 7. 7 b

Nervous Tissue: Neurons · Neurons = nerve cells · Cells specialized to transmit messages http: //www. johnabbott. qc. ca/~p. anderson/806 lab 1/nervoustissue. JPG http: //larvalsubjects. files. wordpress. com/2009/02/neurons. jpg Slide 7. 8

Functional Classification of Neurons · Sensory (afferent) neurons · Carry impulses from the sensory receptors http: //www. colorado. edu/intphys/Class/IPHY 3430 -200/image/10 -1. jpg

Functional Classification of Neurons - Sensory · Sensory receptors· Proprioceptors – detect stretch or tension http: //upload. vipulg. com/Zoology/759/chapter%2029%20 final%20 files_files/chapter%2029%20 final%20 files-1. png

Functional Classification of Neurons - Sensory · Sensory receptors- · Cutaneous sense organs (touch, pressure, pain, temperature http: //www. exploringnature. org/graphics/anatomy/sensory%20 organs. jpg

Functional Classification of Neurons - Sensory · Sensory receptors· Rods and cones of eye http: //www. colorado. edu/intphys/Class/IPHY 3730/image/figure 7 -8. jpg

Functional Classification of Neurons - Sensory · Sensory receptors- · Olfactory neurons of nose http: //nobelprize. org/nobel_prizes/medicine/laureates/2004/illpres/images/olfactory. jpg

Functional Classification of Neurons - Sensory · Sensory receptors· Hair cells of ear http: //melbourneaudiologycentre. com. au/img/pics/anatomy. Ear. jpg

Functional Classification of Neurons - Sensory · Sensory receptors· Taste buds http: //blsciblogs. baruch. cuny. edu/mpenaz/files/2010/09/taste-6. gif

Functional Classification of Neurons · Interneurons (association neurons) · Found in neural pathways in the central nervous system http: //img. tfd. com/dorland/thumbs/interneuron. jpg · Connect sensory and motor neurons · Processing the information http: //www. dushkin. com/connectext/psy/ch 02/reflex. gif

Functional Classification of Neurons · Motor (efferent) neurons · Carry impulses from the central nervous system to an effector (muscle or gland) http: //www. ott. zynet. co. uk/polio/lincolnshire/library/gawne/images/pandcmfig 3. gif Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Structural Classification of Neurons · Multipolar · Bipolar · Unipolar Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 16 a

Structural Classification of Neurons · Multipolar neurons – many extensions from the cell body · Motor and interneurons Figure 7. 8 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 16 a

Structural Classification of Neurons · Bipolar neurons – one axon and one dendrite · Found in sensory cells for the ear and eye Figure 7. 8 b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 16 b

Structural Classification of Neurons · Unipolar neurons – have a short single process leaving the cell body · Most sensory neurons Figure 7. 8 c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 16 c

Nervous Tissue: Neurons · Major regions of neurons · Cell body – contains nucleus, metabolic center of the cell · Processes – fibers that extend from the cell body (axons and dendrites) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings ttp: //fau. pearlashes. com/anatomy/Chapter%2017_files/image 002. jpg Slide 7. 8

Neuron Cell Body Location · Most are found in the central nervous system · Gray matter – cell bodies and unmylenated fibers · Nuclei – clusters of cell bodies within the white matter of the central nervous system · Ganglia – collections of cell bodies outside the central nervous system http: //www. google. com/imgres? imgurl=http: //fau. pearlashes. com/anatomy/Chapter%252017_files/image 002. jpg&imgrefurl=http: //fau. pearlashes. com/anatomy/Chapter%252017. htm&usg=__a. Hidh. Dh 150 bg 7 Tc. A 44 E 0 Pa 6 dlx. Q=&h=475&w=711&sz=62&hl=en&start=19&zoom=0&um=1&itbs=1&tbnid=1 D 2 a. Enmm. LVEb 2 M: &tbnh=94&tbnw=140&prev=/image s%3 Fq%3 Dcell%2 Bbodies%2 Bof%2 Bneurons%26 um%3 D 1%26 hl%3 Den%26 sa%3 DG%26 rlz%3 D 1 T 4 ADBF_en. US 314 US 324%26 tbs%3 Disch: 1

Neuron Anatomy- Cell body · Nucleus · Large nucleolus Figure 7. 4 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 9 b

Neuron Anatomy- Cell Body · Nissl substance – specialized rough endoplasmic reticulum http: //vanat. cvm. umn. edu/neur. Hist. Atls/pages/images/Neuron 7. jpg Figure 7. 4 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 9 a

Neuron Anatomy- Cell Body · Neurofibrils – intermediate cytoskeleton that maintains cell shape Figure 7. 4 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings http: //www. pathology. vcu. edu/Wir. Self. Inst/neuro_med. Students/image/016 neurfib. jpg Slide 7. 9 a

Neuron Anatomy · Axon hillock · Enlarged projection of the cell body where the nervous impulse undergoes summation (“accumulates”) until it reaches threshold (the amount of energy needed to start an impulse) http: //www. ouhsc. edu/histology/Glass%20 slides/3_09. jpg http: //z. about. com/d/psychology/1/5/H/axonhillock. jpg

Neuron Anatomy · Extensions outside the cell body · Dendrites – conduct impulses toward the cell body · Axons – conduct impulses away from the cell body Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7. 4 a Slide 7. 10

Nerve Fiber Coverings · Schwann cells – produce myelin sheaths in jellyroll like fashion · Nodes of Ranvier – gaps in myelin sheath along the axon Figure 7. 5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 12

The Action Potential · If the action potential (nerve impulse) starts, it is propagated over the entire axon (all-ornone) · Summation- the energy accumulates at the axon hillock until it reaches threshold (the amount of energy needed to carry out an impulse) http: //www. ncbi. nlm. nih. gov/bookshelf/br. fcgi? book=mcb&part=A 6187 Slide 7. 19

The Action Potential · The plasma membrane at rest is polarized · Fewer positive ions are inside the cell than outside the cell Slide 7. 19 cwx. prenhall. com/. . . /custom 1/deluxe-content. html

Starting a Nerve Impulse · Depolarization – a stimulus reverses the charge across the nerve cell membrane · A deploarized membrane allows sodium (Na+) to flow inside the membrane · The exchange of ions initiates an action potential in the neuron Figure 7. 9 a–c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 18

Nerve Impulse Propagation · The impulse continues to move away from the cell body · Impulses travel faster when fibers have a myelin sheath Animation: http: //www. blackwellpublishing. com/matthews/actionp. html Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Repolarization · Potassium ions rush out of the neuron after sodium ions rush in, which repolarizes the membrane or brings it back to resting state · The sodium-potassium pump restores the original configuration · This action requires ATP · Sodium ions are pumped back out and potassium ions are pumped back in http: //upload. wikimedia. org/wikipedia/commons/thumb/a/a 5/Scheme_sodium-potassium_pump-en. svg/635 px-Scheme_sodium-

Axons and Nerve Impulses · Axons end in axonal terminals · Axonal terminals contain synaptic vesicles with neurotransmitters http: //sakshat. amrita. ac. in/Virtual. Lab/images/neuron. png Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 11

Axons and Nerve Impulses · Axonal terminals are separated from the next neuron by a gap · Synaptic cleft – gap between adjacent neurons · Synapse – junction between nerves Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 11 http: //www. psiwebsubr. org/SUBR/studyguides/210/neuronscomm. png

http: //www. lionden. com/graphics/AP/synapse. jpg Nerve Impulse · Impulses are able to cross the synapse to another nerve · The synaptic vesicles fuse the membrane · The neurotransmitter is released from a nerve’s axon terminal (on the pre-synaptic neuron) into the synapse · The neurotransmitter attaches to the dendrites of the next neuron (postsynaptic neuron) · An action potential may be started in the dendrite of the next neuron

Neurotransmitters may be excitatory or inhibitory. Excitatory- lead to changes that generate an action potential in the responding neuron http: //webspace. ship. edu/cgboer/receptorsite. gif

Inhibitory- tend to block the changes that cause an action potential to be generated in the responding cell http: //www. nutramed. com/brain/neuron 2. jpg

CLASSIFICATION OF NEUROTRANSMITTERS MONOAMINES Serotonin -mainly inhibitory -plays a role in the regulation of mood; in the control of eating, sleep and arousal; and in the regulation of pain

CLASSIFICATION OF NEUROTRANSMITTERS MONOAMINES (CONT. ) Serotonin -the cell bodies of these neurons lie primarily in the pons, medulla, and midbrain structures http: //salmon. psy. plym. ac. uk/year 1/psy 128 anxiety/serotonin 1. gif

CLASSIFICATION OF NEUROTRANSMITTERS MONOAMINES (CONT. ) Dopamine (catecholamine) -the brain contains several dopaminergic systems, the most important of which are locations in the midbrain - substantia nigra, ventral tegmental area -implicated in several functions: movement, attention, learning and the reinforcing effects of drugs of abuse

Animationhttp: //www. methinsideout. com/animations/NDT. html http: //drugabuse. gov/pubs/teaching 2/largegifs/slide 8. gif

CLASSIFICATION OF NEUROTRANSMITTERS MONOAMINES (CONT. ) Epinephrine (adrenaline) -manufactured in the adrenal cortex -secreted by the adrenal medulla when the sympathetic nervous system is stimulated - causes vasoconstriction, increased heart rate and respiration, increased energy to muscles

CLASSIFICATION OF NEUROTRANSMITTERS MONOAMINES (CONT. ) Norepinephrine (noradrenaline) -may be excitatory or inhibitory depending on the receptor type -the cell bodies of most are located in seven regions of the pons (breathing) and medulla (heart rate, breathing, swallowing), and one region of the thalamus (relay station) -the main neurotransmitter of ganglion cells in the sympathetic (“fight or flight”) nervous system -a “feeling good” neurotransmitter

CLASSIFICATION OF NEUROTRANSMITTERS Acetylcholine (ACh) -excitatory to skeletal muscle and viscera (organs) -primary neurotransmitter secreted by efferent (coming from the CNS) axons. -all muscular activity is accomplished by the release of acetylcholine -ACh is also found in the ganglia (cell bodies) of the autonomic nervous system (“automatic”) and at the target organs of the parasympathetic nervous system (“resting and digesting”).

CLASSIFICATION OF NEUROTRANSMITTERS Amino Acids Glutamate (glutamic acid) -excitatory effects (it is the most important excitatory neurotransmitter in the brain) -important in learning and memory http: //www. sbs. utexas. edu/bio 361 t/images/Glutamate-Science. gif

CLASSIFICATION OF NEUROTRANSMITTERS GABA (gammaaminobutyric acid) -inhibitory effects (it is the most important inhibitory neurotransmitter in the brain) -produced in the substantia nigra

CLASSIFICATION OF NEUROTRANSMITTERS Peptides Endorphins and enkephalins -Opioids naturally found in body that are generally inhibitory

CLASSIFICATION OF NEUROTRANSMITTERS Peptides Endorphins and enkephalins -Several different neural systems are activated when opiate receptors are stimulated: Analgesia - pain reduction inhibition of defensive responses such as fleeing and hiding Stimulation of neurons involved in reinforcement (“reward") Substance P -generally excitatory -blocking its release reduces pain

Neurotransmitters fitting to the receptor site is specific, like lock and key. Only certain shape will fit on certain receptors. http: //www. vikingnet. org/cook/modneurotransmitters 3. jpg

Neurotransmitters are inactivated in several ways: -Broken down by an enzyme -Reabsorbed (also known as reuptake) by transporter molecules in the axon that released them -Diffuse away from the site -Are removed from the site from glial cells http: //facpub. stjohns. edu/~yoburnb/pages/dictimages/reuptake 2. gif

Regions of the Brain · Cerebral hemispheres · Diencephalon · Brain stem · Cerebellum Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cerebral Hemispheres (Cerebrum) · Paired (left and right) superior parts of the brain · Include more than half of the brain mass cwx. prenhall. com/. . . /custom 1/deluxe-content. html

Cerebral Hemispheres (Cerebrum) · The surface is made of ridges (gyri) and grooves (sulci) 1 - Central sulcus 2 - Precentral gyrus 3 - Postcentral gyrus 10 - Lateral sulcus 16 - Parieto-occipital sulcus Figure 7. 13 a Slide 7. 28 b

Lobes of the Cerebrum · Fissures (deep grooves) divide the cerebrum into lobes · Surface lobes of the cerebrum · Frontal lobe · Parietal lobe · Occipital lobe · Temporal lobe Slide 7. 29 a

Specialized Areas of the Cerebrum · Somatic sensory area – receives impulses from the body’s sensory receptors · Primary motor area – sends impulses to skeletal muscles · Broca’s area – involved in our ability to speak Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 30

Specialized Area of the Cerebrum · Cerebral areas involved in special senses · Gustatory area (taste) · Visual area (sight) · Auditory area (hearing) · Olfactory area (smell) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 32 a

Specialized Area of the Cerebrum · Interpretation areas of the cerebrum · Speech/language region · Language comprehension region · General interpretation area Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 32 b

Layers of the Cerebrum · Gray matter · Outer layer · Composed mostly of neuron cell bodies Figure 7. 13 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 33 a

Layers of the Cerebrum · White matter · Fiber tracts inside the gray matter · Example: corpus callosum connects hemispheres Figure 7. 13 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 33 b

Layers of the Cerebrum · Basal nuclei – internal islands of gray matter Figure 7. 13 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 33 c

Diencephalon · Sits on top of the brain stem · Enclosed by the cerebral heispheres Slide 7. 34 a

Diencephalon · Made of three parts · Thalamus · Hypothalamus · Epithalamus Slide 7. 34 a

Thalamus · Surrounds the third ventricle · The relay station for sensory impulses · Transfers impulses to the correct part of the cortex for localization and interpretation Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 35

Hypothalamus · Under the thalamus · Important autonomic nervous system center · Helps regulate body temperature · Controls water balance · Regulates metabolism

Hypothalamus · An important part of the limbic system (emotions) · The pituitary gland is attached to the hypothalamus Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Epithalamus · Forms the roof of the third ventricle · Houses the pineal body (an endocrine gland) · Includes the choroid plexus – forms cerebrospinal fluid Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 37

Brain Stem · Attaches to the spinal cord · Parts of the brain stem · Midbrain · Pons · Medulla oblongata Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 38 a

Midbrain · Mostly composed of tracts of nerve fibers · Has two bulging fiber tracts – cerebral peduncles · Has four rounded protrusions – corpora quadrigemina · Reflex centers for vision and hearing Slide 7. 39

Pons · The bulging center part of the brain stem · Mostly composed of fiber tracts · Includes nuclei involved in the control of breathing Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 40

Medulla Oblongata · · The lowest part of the brain stem Merges into the spinal cord Includes important fiber tracts Contains important control centers · Heart rate control · Blood pressure regulation · Breathing · Swallowing · Vomiting Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 41

Reticular Formation · Diffuse mass of gray matter along the brain stem · Involved in motor control of visceral organs · Reticular activating system plays a role in awake/sleep cycles and consciousness Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 42 a

Cerebellum · Two hemispheres with convoluted surfaces · Provides involuntary coordination of body movements Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 43 a

The Limbic System - Evolutionarily primitive structures -Located on top of the brainstem and buried under the cortex http: //www. umm. edu/images/ency/fullsize/limbic_system_19244. jpg

The Limbic System Involved in : - Emotions and motivations, particularly those related to survival (fear, anger, and emotions related to sexual behavior) - Feelings of pleasure related to survival, such as eating and sex. http: //files. bsc. edu/CLASSES/Terry%20 Goodrick/limbic_system 2. jpg

The Pleasure Circuit Pleasure (reward)- a very powerful biological force for survival. If you do something pleasurable, the brain is wired such that you tend to do it again. Life sustaining activities, such as eating, activate a circuit of specialized nerve cells devoted to producing and regulating pleasure.

The Pleasure Circuit One important set of nerve cells, which uses a chemical neurotransmitter called dopamine, sits at the very top the brainstem in the ventral tegmental area (VTA) Dopamine-containing neurons relay messages about pleasure through their nerve fibers to nerve cells in the nucleus accumbens. http: //www. niaaa. nih. gov/publications/arh 26 -2/26_2 images/brain. gif

The Pleasure Circuit Other fibers reach to a related part of the frontal region of the cerebral cortex. http: //abdellab. sunderland. ac. uk/Lectures/Reward/Pics/DAsystem. png

SUBSTANTIA NIGRA Another part of the brain effected by drugs is the substantia nigra. -Found in the midbrain -Controls movement, attention, releases dopamine, produces GABA, controls eye movement (along with frontal eye field) -One of the two primary output nuclei of the brain's basal ganglia http: //www. memorylossonline. com/glossary/substantianigra. jpg

Cerebrospinal Fluid · Similar to blood plasma composition · Formed by the choroid plexus · Forms a watery cushion to protect the brain Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 46

Location of the Cerebrospinal Fluid Circulated in arachnoid space, ventricles, and central canal of the spinal cord Figure 7. 17 b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 47 b

Protection of the Central Nervous System · Scalp and skin · Skull and vertebral column · Meninges Figure 7. 16 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 44 a

Protection of the Central Nervous System · Cerebrospinal fluid · Blood brain barrier Figure 7. 16 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 44 b

Meninges · Dura mater · Double-layered external covering · Periosteum – attached to surface of the skull · Meningeal layer – outer covering of the brain · Folds inward in several areas Slide 7. 45 a

Meninges · Arachnoid layer · Middle layer · Web-like · Pia mater · Internal layer · Clings to the surface of the brain Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 45 b

Blood Brain Barrier · Includes the least permeable capillaries of the body · Excludes many potentially harmful substances · Useless against some substances · Fats and fat soluble molecules · Respiratory gases · Alcohol · Nicotine · Anesthesia Slide 7. 48

Spinal Cord · Extends from the medulla oblongata to the region of T 12 · Below T 12 is the cauda equina (a collection of spinal nerves) · Enlargements occur in the cervical and lumbar regions Figure 7. 18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 52

Spinal Cord Anatomy · Exterior white mater – conduction tracts Figure 7. 19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 53 a

Spinal Cord Anatomy · Internal gray matter - mostly cell bodies · Dorsal (posterior) horns · Anterior (ventral) horns Figure 7. 19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 53 b

Spinal Cord Anatomy · Central canal filled with cerebrospinal fluid Figure 7. 19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 53 c

Spinal Cord Anatomy · Meninges cover the spinal cord · Nerves leave at the level of each vertebrae · Dorsal root- contains sensory (afferent) neurons · Associated with the dorsal root ganglia – collections of cell bodies outside the central nervous system · Ventral rootcontains motor (efferent) neurons Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 54

http: //www. biology. ualberta. ca/courses. hp/zoo. 225/Spinal. Cordmodel. JPG 1 - Ventral fissure 7 - Posterior median sulcus 2 - Ventral column 8 - Central canal (contains CSF) 3 - Ventral root- motor 4 - Lateral horn 5 - Dorsal root ganglion- collection of cell bodies 6 - Dorsal root- sensory 9 - Dorsal horn 10 - Central commissure 11 - Ventral horn 12 - Spinal nerve

Central Nervous System (CNS) · CNS develops from the embryonic neural tube · The neural tube becomes the brain and spinal cord · The opening of the neural tube becomes the ventricles · Four chambers within the brain · Filled with cerebrospinal fluid Slide 7. 26

Development Aspects of the Nervous System · The nervous system is formed during the first month of embryonic development · Any maternal infection can have extremely harmful effects · The hypothalamus is one of the last areas of the brain to develop Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 75 a

Development Aspects of the Nervous System · No more neurons are formed after birth, but growth and maturation continues for several years · The brain reaches maximum weight as a young adult Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7. 75 b