Ch 5 Nervous System PDF

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Ch 5 Nervous System...

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Chapter 5 NERVOUS SYSTEM Introduction The nervous system is one of two main body systems charged with regulating homeostasis. The system is divided into two main branches, the central nervous system (CNS) and the peripheral nervous system (PNS). Macroscopically it consists of the brain, spinal cord, nerves, and ganglia. Microscopic features include the cells that actually transmit electrical signals called neurons, and the supporting cells called neuroglia. The purpose of this lab is to become familiar with the microscopic features and functions of the neurons and neuroglia, to study the parts of the brain and spinal cord (including the cranial nerves), and learn specified nerves and nerve plexuses. Objectives: 1. Identify nervous tissue and specific structures of nervous tissue on models, diagrams, and microscopic slides. 2. Identify structures of the brain and its coverings on models, diagrams, and preserved specimens. 3. Identify structures of the spinal cord and its coverings on models, diagrams, and preserved specimens. 4. Identify the structures of a nerve. 5. Describe locations and functions of the cranial nerves and of representative spinal nerves. 6. Describe the nervous activity involved in a reflex, and test certain reflexis. Prelab Assignment Prior to attending lab, study in your textbook the overview of the nervous system in Chapter 12. Also, study the properties of neurons and supportive cells in Chapter 12. Consider the spinal cord and the spinal nerves in Chapter 13. Study the overview of the brain; meninges, ventricles, cerebrospinal fluid, and blood supply; the hindbrain and midbrain; and the forebrain.

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NERVOUS SYSTEM Ⅰ. Nervous Tissue Exercise 1: Neuron and Neuroglia A. Identify the following nervous tissue structures on model: Neuron Neuroglia Cell body (neurosoma): Nissl bodies Dendrites Axon: axon hillock, myelin sheath, nodes of Ranvier, axon terminal

Schwann cell Oligodendrocyte

B. Label the following diagram:

Dendrites

Cell body

Axon Axon hillock Axon terminal

Myelin sheath Nodes of Ranvier Figure 5.1 Nervous Tissue

Exercise 2: Nervous Tissue Histology Identify: Neuron cell body, nucleus, dendrites, and nuclei of neuroglial cells.

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Exercise 3: Nerve Synapse Label the terms in the following diagram: Synaptic knob (end bulb) synaptic vesicles

synaptic cleft

neurotransmitter receptors

Synaptic vesicles Synaptic knob

Synaptic cleft

Neurotransmitter Neurotransmitter receptors

Figure 5. 2 N erve Synapse

Check Your Understanding Protecting the nerves from other electrical 1. What is the function of the myelin sheath? _____________________________________

impulses. 2. How do Schwann cells and oligodendrocytes differ in location and shape?

Schwann cells: PNS. Oligodendrocytes: CNS & has arms ___________________________________________________________ 3. Why are synaptic vesicles present in axons but not in dendrites?

Afferent, sending out signals Efferent, receiving information ____________________________________________________________

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Ⅱ. C ra l N e rvo rv o u s Sy Sy s te m : Bra B ra Ce e n tral raii n Exercise 1: Meninges of the Brain Identify the following structures on models: Dura mater: Folds: Falx cerbri, Tentorium cerebelli, Falx cerebelli Arachnoid mater Pia mater Spaces: Subdural, Subarachnoid Label the following diagrams:

Subdural space

Arachnoid mater

Subarachnoid space

Pia mater Falx cerebri

Figure 5. 3 Meninges of the Brain

(Separate the R/L cerebrum) Falx cerbri

Tentorium cerebelli (Separate cerebrum from cerebellum) Falx cerebelli (Separate R/L cerebellum) Figure 5.4 Folds of Dura Mater

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Check Your Understanding Cerebrospinal fluid 1. What substance fills the subarachnoid space? _____________________ 2. What is the function of the arachnoid villi? Are these structures found over the entire surface of the brain? _______________________________________________ 3. What is the function of the falx cerebri and the tentorium cerebelli? Describe their location. ____________________________________________________________________ Exercise 2: Cerebrum A. Surface Anatomy of the Brain: Fissures, Sulci, and Gyri a. Locate the fissures of the cerebrum and notice how they form markings between the two cerebral hemispheres and the cerebellum. b. Identify the location of the sulci and notice how they outline the lobes of the brain. c. Notice the gyri which are thick folds on the brain surface d. On sagittal sections of the brain, identify corpus callosum, cerebral cortex with gray matter and white mater. Fissure Sulcus Gyrus Longitudinal Central Precentral Transverse Lateral Postcentral Parieto-occipital Label the following diagrams:

Central sulcus Longitudinal fissure

Gyrus Precentral gyrus

Central sulcus

Lateral sulcus

Parieto-occipit sulcus

Postcentral gyrus

Transverse fissure

Figure 5.5 Surface Anatomy of the Brain

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B. Ventricles of the Brain Identify the location of these ventricles on models: Fourth ventricle Cerebral aqueduct Lateral ventricles Third ventricle Where is the choroid plexus located and what is its function? _________________ Produce CSF Label the following diagram: Lateral ventricles Lateral ventricle

Choroid plexus

Cerebral aqueduct

Third ventricle

Fourth ventricle Figure 5.6 Ventricles of the Brain

C. Cerebral Lobes Identify these structures on models: Frontal Parietal Temporal

Occipital

D. Functional Areas of the Brain Functional Area Location Function Primary motor cortex Primary somatosensory cortex Primary visual cortex Primary auditory cortex Broca’s area Wernicke area Label the lobes and functional areas in the following diagram: Primary motor cortex Primary somatosensory cortex Parietal Wernicke area Broca’s area Occipital Primary visual cortex

Frontal Temporal

Primary auditory cortex

Figure 5.7 Lobes and Functional Areas of Brain

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E. The Diencephalon Identify these structures on models: Epithalamus Thalamus Choroid plexus Pineal gland Label the following diagram:

Hypothalamus

Choroid plexus Thalamus Pineal gland Hypothalamus

Pituitary gland Figure 5.8 Diencephalon

F. The Brain Stem Identify these structures on models: Midbrain Pons

Medulla oblongata

G. The Cerebellum Identify these structures on models: Cerebellar hemispheres Arbor vitae Label the following diagram:

Gray mater

Vermis (Connects 2 cerebellum)

Midbrain Arbor vitae 4th ventricle Pons Gray mater Medulla oblongata

Figure 5.9 Brain Stem and Cerebellum

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Ⅲ. Central Nervous System: Spinal Cord Exercise 1: Gross Anatomy of the Spinal Cord A. Identify the following structures on models of the spinal cord: Cervical and lumbar enlargements Cauda equina Spinal nerves Filum terminale Nerve plexuses

Figure 5.10 Spinal Cord Gross Anatomy

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B. Cross Section of the Spinal Cord Identify the following structures on cross sectional models of the spinal cord: Gray mater Spinal nerve Anterior horn Dorsal root (dorsal root ganglion) Lateral horn Ventral root Posterior horn White mater Meninges Anterior column Dura mater Lateral column Arachnoid mater Posterior column Pia mater Central canal Spaces Subarachnoid space Epidural space Posterior median sulcus Anterior median fissure Label the following diagram: Posterior median sulcus

Posterior horn

Posterior column

Dorsal root Dorsal root ganglion Spine nerve

Central canal Lateral column

Lateral horn Anterior horn

Anterior median fissure Ventral root

Anterior column

Figure 5.11 Cross-sectional Anatomy of Spinal Cord

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Figure 5.12 Cross-section of Spinal Cord Showing Spaces

Check Your Understanding 1. How does the epidural space of the spinal cord differ from that surrounding the brain? Brain: Nothing Spinal cord: Fat _________________________________________

2. What type of neuron fibers (sensory or motor) are found in the dorsal root of a spinal nerve? Dorsal root: Sensory Ventral root: Motor In the ventral root? ____________________________________________

3. Where are the cell bodies for the sensory neurons of a spinal nerve located? The cell bodies for the motor neurons? Dorsal root ganglion _________________________________________________________________________ Gray mater 4. Where are interneurons found in the spinal cord? _________________________

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Ⅳ. Per P er erip ip h eral N ervo ervou u s S ys tem A. Nerve Structure Identify the following structures of peripheral nerves Epineurium Perineurium Myelinated axon

Endoneurium

Figure 5.13 Cross-sectional Anatomy of Nerve

B. Histology of Peripheral Nerve

Identify: nerve fascicles, perineurium, and blood vessels

Check Your Understanding 1. Why are the nodes of Ranvier necessary; i.e., why is the myelin sheath discontinuous?

Allows signal rapidly jumps from node to node; To result saltatory conduction. _____________________________________________________________ 2. What is the term used to describe transmission of an action potential along a myelinated axon?

Saltatory conduction (Unmyelinated is called continuous conduction) _____________________________________________________________ 11

C. Cranial Nerves Use your textbook to locate the cranial nerves on models of the brain. What is the specific function of each cranial nerve? Nerve Sensory or Motor Function I. Olfactory

Sensory

Smell

II. Optic

Sensory

Vision

III. Oculomotor

Motor

4/6 muscle that control eye movements

IV. Trochlear

Motor

A single muscle of the eye

V. Trigeminal

Both

Innervates face and jaw muscles

VI. Abducens

Motor

Eye movement

VII. Facial

Both

Facial expression

VIII. Vestibulocochlear

Sensory

Conduct sound, balancing

IX. Glossopharyngeal

Both

Leads to tongue & phanynx

X. Vagus

Both

Heart & digestive tract

XI. Accessory

Motor

Moves head & shoulder, neck muscles

Motor

Allowing swallowing & talking, pharynx & larynx

XII. Hypoglossal

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