nervous system Flashcards
(33 cards)
what is a multipolar neuone
1 axon, many dendrites
What are the different glial cells in the CNS? and one in the PNS
Astrocyte - growth support
Oligodendrocyte - myelin forming cell, wraps around axons
Microglia - immune function in brain
Ependymal cells - specialised epithelial cells, secrets cerebral spinal fluid.
IN the PN: Schwann cells - myelin forming cell and growth forming and immune role.
What is gray matte?
Cell bodies of neurones reside in gray matter.
Gray matter is on the inside of the spinal cord (but outside the brain)
What is white matter?
Myelinated axons exist.
The myelinated phenotype from the oligodendricytes provide lipid covering, a rich white colour
White matter is on the outside of the spinal cord (inside of the braiN)
The 4 brain divisions
Cerebrum
Diencephalon (middle of brain, above brain stem)
Brain stem
Cerebellum (behind brain stem)
The different lobes
Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
What are sulci and gyri?
Allow “more substance in a closed space.”
Allows the tissue to fold in on itself on the brain.
Sulci - infoldings of the cerebral hemispheres that form “valleys” between the gyri. (The valleys between the mountains)
Gyri - The ridges of the infolded cerebral cortex (it’s the tissue itself, the mountain)
What is the functions of the different brain divisions; Frontal lobe, parietal, Occipital, Temporal
Frontal lobe - motor function
Parietal lobe - somatosensory cortex.
Occipital lobe - vision
Temporal - auditory
What are two areas in the diencephalon that are important and what do they do
Thalamus - major relay station for sensory information coming into the cortex from below (e.g spinal cord and brain stem) - it’s a gate for how many information is coming into the somatosensory cortex. Olfaction doesn’t go through here
Hypothalamus - Autonomic control center - works with endocrine system, helps body sit in homeostasis
What does the brain stem do and what are the three important components?
Less evolved species have a brain stem because it’s the most primitive area of the brain.
Attaches spinal cord to cerebellum and cerebrum.
- mid brain - eye movement
- pons - major relay area between cerebellum and cerebrum
- Medulla oblongata - control center for involuntary function (houses vital center e.g blood pressure, and non-vital centers e.g sneezing)
Cerebellum - balance and coordination
What are the different areas of the spinal cord? and what re they associated with?
Cervical area - neck
thoracic area - chest cavity
lumbar
sarcral area
What protects the CNS? ; bone, meninges
Bone: skull protecting brain, vetrebal column protecting spinal cord
Meninges: cellular layers that surround the tissue, they come in 3 different layer.
- Dura: outer. Tough structural layer, attaches tissue to bone
- Arachnoid: Close to dura, web-like appearance.
- Pia: deepest layer, external layer of brain and spinal cord.
What is the subarachnoid space?
Because of the arachnoid web like appearance, there’s a lot of space between it.
This space contains fluid (CSF)
What does the CSF do?
Protective layer. Cell-free fluid
What does the BBB (blood brain barrier) do?
A barrier composed of endothelial cells and astrocytes.
Prevents free diffusion into the brain by large molecules (>500 daltons MW)
E.g O2, CO2, lipid soluble molecules (hormones can enter
What is an action potential?
A brief change in electrical potential across the cell’s membrane involving the movement of ions across the membrane in response to stimulation.
What is the resting membrane potential of a neurone?
Where the cell sits when it’s not excited.
-70mV (need to know it’s negative).
mV used to characterize membrane potential.
What ions are greater on the outside of the axon than the inside?
Na+ and Cl -
This diagram is on ON
What is the active process that help maintain the RMP?
Sodium potassium ATPASS
active because it requires ATP,
Able to pull 3Na+ out, and 2K+ in.
This is used in CV system.
What are Na+ and K+ mainly responsible for in terms of action potential?
Na+ movement is largely responsible for an action potential (e.g an increase in intracellular Na+ produces an action potential)
K+ is mainly responsible for resting membrane potential
Movement of only a few ions are required to generate the AP because the cell’s lipid membrane is…
a capacitor which STORES electrical charge.
What properties of a neuron allow for rapid conduction of signals?
- positive feedback
- Myelination (fatty substance), increases ratio of outwardsResistance/InwardsResistance, helps to insulate even further where the AP’s occur on the axons. Increased resistance = faster action potential
What are nodes of randvier?
Little gaps between the myelin.
At each node there are a huge abundance of voltage gated sodium channels.
There’s a high level of insulation and so an action potential happens at a node and then it jumps to the other node
The AP travels in a “saltatory conduction” manner
Example of an unmyelinated axon
Pain fibres.
Sensory fibres
AP travels in a “continuous conduction” manner, it’s much slower than saltatory.
