Exam 4 Flashcards
(169 cards)
Central Nervous System
brain (97% of nervous tissue) and spinal cord
Grey Matter (nuclei)
groups of neuronal cell bodies in the CNS
White Matter (tracts or fibers)
the bundles of axons which are myelinated in the CNS
Ganglia
groups of neuronal cell bodies in the PNS
Nerves
the bundles of axons in the PNS
How is the brain protected?
skin, cranial bones, cranial meninges, cerebrospinal fluid (made from plasma)
What are the cranial meninges?
dura mater (thick fibrous), arachnoid (thin fibrous and filamentous mesh), pia mater (thin fibrous)
Sinus
a special type of vein that does not contain smooth muscle in it
What happens in the subarachnoid space?
the cerebrospinal fluid circulates there
The purpose of cerebrospinal fluid (CSF)
homeostatic regulation of ions and nutrients, support, immune functions
Where is CSF produced?
First produced in lateral ventricles then flow through the interventricular foramen into the third ventricle producing more CSF which flows through the cerebral aqueduct into the fourth ventricle. From here the fluid can exit and flow around the brain or some of it will exit and flow to the spinal cord
How do we drain CSF?
The fluid is in the subarachnoid space where there is a good amount of pressure from the constantly created CSF that creates bulk flow and some of the CSF will drain into the dural space into the dural sinuses and the CSF will become part of the blood
Choroid plexus
the majority of the CSF is produced here, lining in the ventricles, tight junctions between internal capillaries and ependymal cells create a selective gradient that allows specific ions
How do plasma and CSF differ?
CSF has higher concentration of water and lower concentration of protein, high concentrations of sodium which make depolarization happen more rapidly
Blood brain barrier
endothelial cells with microvessels, exhibit complex tight junctions, everything must go through the barrier to get from plasma to CSF, contain parasites which integrate and process signals to help regulate the flow of nutrients and waste through the network of cells, contain astrocytes that help promote the tight junctions formation in the specialized neuroglia that extend to number of capillaries
What is the neurovascular unit and their function?
endothelium, astrocytes and parasites which controls molecular traffic to keep out toxins, creating ion homeostasis, creating low protein environment in the CSF
How do we create energy within the brain?
Consume lots of oxygen which passes freely across the blood brain barrier and the brain consumes about 15% of blood pumped by heart at rest, consumes lot of glucose which is about half of the body, membrane transporters move glucose from plasma into brain interstitial fluid
What happens if there is a lack of glucose in the brain?
progressive hypoglycemia that leads to confusion, unconscious and progressive unconsciousness and potentially death
What parts of the brain supply the blood?
internal carotid arteries - supplies anterior parts of brain, vertebral artery - supplies posterior parts of brain
Circle of Willis
a circle that provides redundant blood supply and prevent irreversible damage
How does the blood return?
Venous return happen through jugular veins
Cerebrum
highly folded, higher level thinking, responsible for conscious, motor control, and sensory perception
Diencephalon
responsible for homeostatic controls, smooth muscle control, temperature regulation
Function of brainstem
responsible for autonomic/reflex center (breathing or cardiac rhythm)