BIO 210 Lab Handout

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BIO 210 Lab Handout 10 Nervous System Cell
body large rounded region of the cell
biosynthetic center of the cell contains all
organelles except centrioles. Nucleus large,
round found in cell body Neurofibrils
cytoskeletal elements of the neuron Nissl
bodies elaborate rough ER dark staining bodies
protein synthesis Mitochondria everywhere
synthesize ATP Dendrite short, branching
processes close to the cell body main receptive
or input region convey signals toward the cell
body contains all organelles Axon - only 1
per neuron very long axons are nerve fibers
the conducting component of the neuron
generate nerve impulses do not have Nissl
bodies or Golgi Axon hillock cone shaped area
of the cell body leading to the axon Axon
terminal knoblike distal endings of terminal
branches Secretory component of the neuron
stores neurotransmitters in vesicles Myelin
sheath whitish, fatty covering on axon
protects, electrically insulates nerves
increases speed Schwann Cell neuroglia that
forms myelin sheath in PNS
Nodes of Ranvier gaps in the myelin sheath
Schwann cells do not touch each other
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Supporting Cells (Neuroglia) Central Nervous
System 4 types 1. Astrocytes star shaped
radiating processes cling to neurons and
capillaries anchoring them to their nutrient
supply mop up leaked potassium ions and recycle
released neurotransmitters control the chemical
environment around neurons 2. Microglia small
ovoid cells with long thorny processes to touch
and monitor neurons transform into a macrophage
that phagocytizes invading microorganisms or
debris from dying neurons monitor health of
neurons
3. Ependyma squamous to columnar, may be
ciliated line central cavities of the brain and
spinal cord form a semipermeable membrane
beating cilia circulates cerebrospinal fluid
4. Oligodendrocyte forms myelin sheaths in
the CNS

• Peripheral Nervous System
• Schwann cells form myelin sheaths around larger
  nerve fibers in the PNS
• Satellite cells surround neuron cell bodies
  within ganglia

• Brain
• The brain is generally divided into 4 major
  regions
• Cerebrum most superior portion of the brain
  localizes and interprets sensory inputs controls
  voluntary and skilled activity intellectual and
  emotional processing
• Diencephalon central core of the brain
  surrounded by the cerebrum relay station to
  conduct sensory impulses to the cerebrum relay
  station for impulses to and from cerebral motor
  cortex memory processing integration center for
  involuntary nervous system regulates hormonal
  output of the pituitary gland produces oxytocin
  and antidiuretic hormone
• Brain stem between the cerebrum and the spinal
  cord visual and auditory reflex centers relays
  information from the cerebrum to the cerebellum
  controls respiration, heart rate, vomiting,
  coughing, etc. sensory relay to the cerebellum
• Cerebellum cauliflower-like dorsal to the
  brain stem processes information from the
  cerebral cortex and instructs the cerebral motor
  cortex resulting in proper balance, posture and
  smooth, coordinated movements

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• Ventricles cavities within the brain filled
  with cerebrospinal fluid continuous with central
  canal of spinal cord lined by ependymal cells
• Lateral two large C-shaped chambers deep
  within the cerebral hemispheres
• Third narrow within the diencephalon
• Fourth dorsal to the brain stem continuous
  with the spinal canal apertures connect to the
  subarachnoid space surrounding the brain with
  fluid
• Cerebral aqueduct canal-like channel that
  connects the third and fourth ventricles

Brain Exterior Meninges 3 layers of connective
tissue membranes that cover and protect the brain
spinal cord 1. Dura Mater outermost,
tough leather, double layer 2. Arachnoid
middle layer has threadlike spider web
projections to the inner layer 3. Pia Mater
innermost delicate, highly vascular, clings
tightly to brain surface
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Cerebrum 4 Lobes Frontal Parietal Temporal Occi
pital
Longitudinal fissure separates the two cerebral
hemispheres Transverse fissure separates the
cerebrum from the cerebellum Gyri elevated
ridges of tissues Sulci depressed areas between
the gyri Cerebral Cortex gray matter of the
brain it is located in the gyri
Gyrus
Sulcus
Gray matter contains clusters of Neuron Cell
Bodies in the cortex
Cerebral cortex
Longitudinal Fissure
12 Cranial Nerves
I Olfactory bulb sensory for smell
II Optic chiasma sensory for vision
III Oculomotor mixed for eye movement
IV Trochlear mixed for eye movement
Facial VII Mixed for taste, facial expressions
V Trigeminal mixed for facial expression
chewing
Vestibulocochlear VIII Sensory for hearing,
balance
VI Abducens mixed for eye movement
Glossopharyngeal IX Mixed for taste, swallowing
Vagus X Mixed for organ sensations, movements
Accessory XI Mixed for head, neck movement
XII Hypoglossal mixed for tongue movement
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Cerebrum 3 deep components 1. Corpus callosum
major tract of fibers connecting the two cerebral
hemispheres 2. Septum pellucidum membrane
separating lateral ventricles of the cerebral
hemispheres 3. Fornix bandlike fiber tract
inferior to septum pellucidum
Diencephalon 3 parts 1. Epithalamus forms
roof of the 3rd ventricle A. Pineal body
usually dark from producing melatonin posterior
to the thalamus 2. Thalamus 2 large lobes of
gray matter lateral walls of 3rd
ventricle Intermediate mass slender stalk of
thalamic tissue that connects the 2 lobes
bridges the ventricle
3. Hypothalamus floor of the 3rd ventricle
under the thalamus Pituitary gland hangs
from the the hypothalamus by the
infundibulum, Mammillary bodies bulge
exteriorly from the floor of the hypothalamus
posterior to the pituitary gland
Fornix
Septum pellucidum
Corpus Callosum
Cerebrum
Third ventricle
Intermediate mass
Thalamus
Pineal body
Hypothalamus
Corpora quadrigemina
Optic chiasma
Cerebral aqueduct
Pons
Infundibulum
Cerebellum
Midbrain
Arbor vitae
Medulla oblongata
Fourth ventricle
Central canal
Spinal cord
Brain Stem has 3 parts 1. Midbrain between
the Diencephalon and the Pons contains the
Cerebral aqueduct and the Corpora quadrigemina 2.
Pons 3. Medulla oblongata Cerebellum 2 small
lateral hemispheres outer cortex is gray
matter Arbor vitae tree-like branches of
white matter
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• Dissection of the Sheep Brain
• Use safety glasses
• Put the bag containing a sheep brain in the
  dissecting tray
• Cut the bag near the top and rinse the brain with
  running tap water
• Pat the brain with paper towels to remove excess
  water
• Examine the surface of the brain. Locate the
  following
• Dura mater
• Olfactory bulbs (cranial nerve I)
• Optic chiasma (cranial nerve 2)
• Pituitary gland Infundibulum

• Carefully cut away the dura mater from the
  cerebral hemispheres with scissors
• Cut the dura mater from the optic chiasma and the
  pituitary gland
• Snip the Dura mater between the cerebellum and
  the cerebral hemispheres and pull it all the way
  out
• Identify the following on the cerebral
  hemispheres
• Gyri
• Sulci
• Longitudinal fissure
• Transverse fissure
• Frontal lobe
• Parietal lobe
• Temporal lobe
• Occipital lobe
• Pia mater

• Gently separate the cerebral hemispheres along
  the longitudinal fissure to see the white fibers
  of the corpus callosum
• Gently bend the cerebellum down and away from the
  cerebral hemispheres. Locate the following
• Arachnoid
• Corpora quadrigemina
• Pineal gland

• On the ventral side of the brain, locate the
  following
• Olfactory bulbs
• Optic nerves
• Optic chiasma
• Infundibulum (pituitary stalk)
• Mammillary bodies (just inferior to infundibulum)
• Trigeminal nerve

• Use a long sharp knife to cut the brain along the
  midline to produce a midsagittal section

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• Brain Dissection Continued
• Locate the following structures of the cerebrum
• Cerebral hemispheres
• Cerebral cortex
• Corpus callosum
• Septum lucidum
• Fornix
• Lateral ventricle

• Locate the following structures of the
  diencephalon
• Optic chiasma
• Infundibulum
• Pituitary gland
• Thalamus
• Pineal gland
• Hypothalamus
• Mammillary bodies
• Third ventricle

• Locate the following structures of the brain stem
• Midbrain
• Corpora quadrigemina
• Cerebral aqueduct
• Pons
• Medulla Oblongata
• 4th ventricle

• Locate the following structures of the cerebellum
• Arbor vitae
• Gray matter

• Return the dissected brain to its bag and add 1-2
  ounces of Carosafe
• Close the bad securely with staples and label it
  with your name
• Wash and dry all instruments and dissecting tray
  return to proper storage

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