Central Nervous System 2
Terms in this set (51)
central nervous system
I. The Brain Interpret sensory info, issue appropriate motor commands, carry on all higher intellectual functions
III. Brain Stem
Forms the surface area (what you see when you first look at the brain, and hold it in your hand) of the brain called the cortex. It is mostly made of unmyelinated fibers and cell bodies.
Lies deep to the cortical gray matter. A dense collection of myelinated fibers calls tracts, or bundles of axons that are connected to one part of the brain to another.
Interpret sensory info, issue appropriate motor commands, carry on all higher intellectual functions.
a. Cerebral Hemispheres
> Longitudinal fissures
most superior part of the brain
=elevated wrinkle or fold in the cortex of the cerebrum or cerebellum.
=shallow grooves between gyri.
=deeper grooves that separate larger regions of the brain.
=fissures or sulci that further divides the hemispheres
-primary motor area of cerebrum. Thinking, reasoning, speech.
part of the decending tracts that conduct motor impulses down the spinal cord.
generates a motor program for the muscles of the larynx, tongue, cheeks and lips to produce speech. Damage to the area reduces a persons ability to articulate words
Superficial gray matter
Deep white matter
tracts that carry information to or from the cortex
connects the cerebral hemispheres. It joins the functions of the hemispheres so that the right and left sides communicate.
--. "islands' of gray matter buried within the white matter. Their function is to regulate voluntary motor activities by modifying instructions sent to skeletal muscle by the primary motor cortex Parkinson's disease patients have degeneration in this area.
(interbrain) located on top of the brain stem and enclosed by the cerebral hemispheres.
relay station for sensory impulses
relay station for the ANS. Includes the
pituitary gland, mammillary bodies
Helps to make CSF. Includes the pineal
body, choroids plexus
(under-side of Brain) thumb size, approx 3 in long
-regulates vital life activities (BP,
extends the entire length of the
brainstem and is composed of gray matter. It is responsible for motor control of visceral organs.
consciousness and awake/sleep cycles
: Second largest part of the Brain. Located below and
partially covered by the cerebellum. Coordinates voluntary movement and makes movement smooth. Helps to maintain balance/equilibrium. 2 hemispheres, outer cortex of gray matter, and inner region of white matter.
• 17 inches long depending on the persons height
• continuation of the brain stem
• 2 way conduction pathway to and from the brain and a major reflex center
• extends from the foramen magnum to the first or second lumbar vertebra
just below the ribs
• During spinal tap, you remove CSF around L3 because in this area there
is less of a chance of damaging the spinal cord
Protecting the CNS
Meninges 3 connected be tissue
vertebrae, skull bones
-3 connective tissue coverings that protect the brain and
Arachnoid matter-middle layer.
Pia matter-innermost layer.
outermost protective layer, very tough.
1. Subdural space
middle layer. Delicate, web-like.
1. Subarachnoid space
Cerebral Spinal Fluid (CSF)
Fluid occupying the 4 ventricles of the brain, the space between the meninges, and the central canal of the spinal cord.
Brain floats in CSF and therefore reduces brain weight.
• Composition similar to blood plasma from which it arises
• Contains Vitamins C, Na, Cl, Mg, H, and less Ca and K.
• pH is important in control of cerebral blood flow and breathing
• Transports hormones
• The Choroid Plexuses that hang from the roof of each ventricle produce CSF
Tissue fluid filters through capillaries in this area from the blood stream. The ependymal cells of the ventricles only allow certain ions in and water to diffuse into the ventricles.
• Adults CSF = 1/2 cup is replaced every 3 to 4 hours
• Constant motion of CSF is aided by ciliated ependymal cells
• CSF returns to the blood in the dural sinuses via the arachnoid villi
Ventricles of the Brain:
a. continuous with each other and with the central canal of the spinal cord.
b. Filled with CSF (cerebral spinal fluid)
c. Lined with ependymal cells
(1st and 2nd Ventricles)
1. "C" shaped
2. located deep with in each cerebral hemisphere
3. each lateral ventricle communicates with the third ventricle via the interventricular foramen.
1. located in diencephalon
2. continuous with the fourth ventricle via the canal-like cerebral aqueduct that runs through the midbrain.
1. located dorsal to pons and superior to medulla
2. continuous with central canal of spinal cord
3. 3 openings (apertures) connect the ventricles to the subarachnoid space
• protective mechanism that helps maintain a stable environment for the brain....the brain needs consistency----separated from the extra cellular environment.
• Blood borne substances with in the brain's capillaries are separated from the extra cellular space and neurons by:
1. The continuous endothelium of the capillary wall.
2. Thick basal lamina surface surrounding the external face of the capillary 3. Bulbous "feet" of the astrocyte that cling to the capillary.
• Least permeable capillaries in the entire body. Astrocytes help form these tight junctions by stimulating the endothelial cells to come in extremely close contact.
• The blood brain barrier is ONLY ineffective against fats, fatty acids, oxygen, and carbon dioxide and other fat-soluble molecules such as alcohols, nicotine, and anesthetics can affect the brain.
• We are missing the blood brain barrier in some areas such as:
1. Around the 3rd and 4th ventricles because this is the region of vomiting
center of the brain stem which monitors blood for poisonous substances.
2. Hypothalmus because it regulates the chemical environment and therefore needs to sample the chemical composition of blood
3. Absent in newborns and premature infants....only develops after birth, after skull has closed.
=automatic, involuntary response to some change, either inside or outside the body. They are important in maintaining homeostasis by making adjustments to heart rate, breathing rate, and blood pressure.
components of a reflex arc
2. Sensory Neuron
3. Integration Center
4. Motor Neuron
=Site of stimulus action; receptor end of a dendrite
=Cell body in ganglion outside CNS; axon in CNS
Integration center (CNS)
=In CNS; synapse between sensory and motor neuron, interneurons may also be involved.
=dendrites and cell body in CNS; axon extends into periphery
=muscle or gland outside CNS.
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