Chapter 9: The Central Nervous System Flashcards
- brain and spinal cord
- Responsible for everything we perceive, do, feel, and think
- coordinating the activities of all our organ systems
- Necessary for the maintenance of homeostasis
central nervous system
-Contains 1011 neurons (100 billion)
Contains 1014 synapses (100 trillion)
central nervous system
the restructuring of the brain networks in response to sensory input and experience
plasticity
- Involved in memory
- Affective behaviors- related to feeling and emotion
- Cognitive behaviors- linked to thinking
plasticity
what is involved in the physical support of the CNS?
-bone ~cranium ~vertebral column -meninges ~dura mater ~arachnoid mater ~pia mater -cerebrospinal fluid (CSF) ~cerebroventricles ~clear watery fluid bathing the CNS
cushion the delicate brain tissue
The meninges and extracellular fluid
-Secreted by ependymal cells of the choroid plexus
~Circulates through ventricles to subarachnoid space
~reabsorbed by arachnoid villi
cerebrospinal fluid
what are the functions of cerebrospinal fluid?
- cushions brain
- Maintains a stable interstitial fluid environment
transports ions and
nutrients from the blood
into the cerebrospinal fluid.
choroid plexus
total volume of CSF
125-150 mL
how much CSF does the choroid plexus produce a day?
400-500 mL
how many times is the CSF recycled?
3 times per day
consist of first and second ventricles
lateral ventricles of the brain
extend through the brain stem
and connect to the central canal
that runs through the spinal cord
third and fourth ventricles of the brain
- accounts for 2% of total body weight (3-4 lbs)
- receives 15% of blood supply
CNS
what is the metabolic rate of the CNS?
- high metabolic rate
- Brain uses 20% of oxygen consumed by body at rest
- Brain uses 50% of glucose consumed by body at rest
what does the CNS depend on for energy?
blood flow
depend on aerobic glycolysis
neurons of CNS
Passes freely across blood–brain barrier carriers
oxygen
move glucose from plasma into the brain interstitial fluid (CNS)
membrane transporters
- Sites of exchange between blood and interstitial fluid
- Thin: single layer of endothelial cells
- Diffusion
capillaries of blood brain barrier
- Special anatomy consisting of CNS capillaries that limit exchange
- Protects brain from toxic water soluble compounds and pathogens
blood brain barrier
cross the blood-brain barrier
small lipid soluble molecules
what two regions lack the blood brain barrier?
- hypothalamic-hypophyseal portal system (getting hormones into circulation)
- vomiting center of medulla oblongata (monitoring for toxins)