Download CENTRAL NERVOUS SYSTEM

BIOLOGY 165 CENTRAL NERVOUS SYSTEM LAB MANUAL
NOTE: You may be asked to identify any structure, cell, tissue, or organ labeled in the figures/pictures within
this lab manual. In addition, you may be asked to name one function of each labeled item and one location
within the human body where it can be found. You are only responsible for the specific information contained
within this lab manual. Although the pictures in this packet show a particular model, you should look at all
similar models we have in the lab; any model in lab can be used during the practical.
INTRODUCTION
The central nervous system consists of the brain and the spinal cord.
The Brain
1. Brainstem – with the following functional areas:
a. Medulla oblongata.
i. Contains all ascending and descending tracts that pass between the spinal cord and the
brain.
ii. Contains the decussation of the pyramids where motor tracts cross over to the opposite
side of the central nervous system.
iii. Contains the three vital reflex centers:
1. Cardiac center.
2. Respiratory center.
3. Vasomotor center.
b. Pons – with the following functional areas:
i. Contains the nuclei of some of the cranial nerves.
ii. Contains two vital reflex centers:
1. Pneumotaxic area and apneustic area:
a. These two areas together define the limits of pulmonary ventilation
(inhalation and exhalation).
c. Midbrain – with the following functional areas:
i. Contains the cerebral peduncles that attach the brain stem to the cerebellum.
ii. Contains the corpora quadrigemina with two specialized reflex areas:
1. Superior colliculi – reflex center for visual stimuli.
2. Inferior colliculi – reflex center for auditory stimuli.
2. Cerebellum – the motor area of the brain that coordinates certain subconscious movements of skeletal
muscles required for coordination of body movements, posture, and balance.
3. Diencephalon – contains the following functional areas:
a. Thalamus – functions as a relay station for sensory stimuli between the cerebrum of the brain and
the spinal cord.
b. Hypothalamus – with many functions including:
i. Control and integration of the autonomic nervous system.
ii. Control of secretion of hormones from various endocrine glands.
iii. Control of body temperature.
iv. Feelings of rage and aggression, food intake, thirst, and many more.
c. Pituitary gland – (attached to the hypothalamus by a stalk called the infundibulum) secretes
many hormones.
d. Pineal gland – controls the onset of puberty and other biorhythms.
4. Cerebrum (composed of the left and right cerebral hemispheres) - with the following functional areas:
a. Frontal lobe – contains the primary motor cortex (on the precentral gyrus), which is involved in
the voluntary control of the skeletal muscles, among other things…
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b. Parietal lobe – contains the primary sensory cortex (on the postcentral gyrus) which is involved
in the conscious perception of touch, pressure, pain, vibration, taste and temperature, among
other things…
c. Temporal lobe – involved in the conscious perception of sound and smell, among other things…
d. Occipital lobe – involved in the conscious perception of visual stimuli, among other things…
e. Corpus callosum – connects regions of one hemisphere of the cerebrum with the same regions on
the other hemisphere of the cerebrum.
Be able to identify the structures shown in the pictures below, using any similar model we have in lab.
Parietal
lobe
Frontal
lobe
Temporal
lobe
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Occipital
lobe
Hypothalamus
Superior colliculus of the
corpora quadrigemina
Inferior colliculus of the
corpora quadrigemina
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Ventricles of the Brain
The central nervous system contains chambers (ventricles) where cerebrospinal fluid (CSF) is produced. This
fluid is produced by capillaries called the choroid plexus, found within the lateral, third, and fourth ventricles.
1. Lateral ventricles – one is located in each cerebral hemisphere of the brain. Each contains a capillary
bed called the choroid plexus that produces CSF.
2. Interventricular foramen – drains the CSF from the two lateral ventricles into the third ventricle.
3. Third ventricle – also contains a choroid plexus for the production of CSF.
4. Cerebral aqueduct – drains the CSF from the third ventricle into the fourth ventricle.
5. Fourth ventricle – also contains a choroid plexus for the production of CSF.
6. The CSF drains from the fourth ventricle into the central canal of the spinal cord and into the
subarachnoid space around the brain and spinal cord. It is then reabsorbed into the blood.
Seen below: Ventricles of the brain. Be able to identify the structures shown in the picture below, using any
similar model we have in lab.
Spinal Cord
1. Meninges – three coverings of connective tissue that surround the brain and spinal cord:
a. Dura mater – the outer layer of the meninges, consisting of dense fibrous connective tissue.
b. Arachnoid mater – the middle layer of the meninges, composed of very delicate connective
tissue.
i. Beneath the arachnoid mater is the subarachnoid space, which contains CSF.
c. Pia mater – the inner layer of the meninges is composed of a delicate transparent fibrous
membrane. It adheres tightly to the surface of the brain and spinal cord. It also forms the
denticulate ligaments and filum terminale that holds the spinal cord in place.
2. Spinal cord structures:
a. The dorsal roots – contains the fibers of the incoming (afferent) sensory neurons.
b. The ventral roots – contains the fibers of the outgoing (efferent) motor neurons.
c. The spinal nerves – contains both sensory and motor fibers.
d. The dorsal root ganglia – contains the cell bodies of the sensory neurons.
e. Gray matter – contains the cell bodies of neurons.
f. White matter – contains the myelinated axons of motor and sensory neurons.
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Be able to identify the structures shown in the pictures below, using any similar model we have in lab.
Seen below: Model of the spinal cord within a cervical vertebra. Note: The three meninges and associated
spaces are shown in a close-up view on the next page, and are named individually.
Dorsal root ganglion
Ventral root
Dorsal root
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Seen below: Meninges and spinal cord.
Ventral horns
Dorsal horns
Arachnoid mater
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