Nervous System Flashcards
What are the two main divisions of the nervous system
Central nervous system
peripheral nervous system
what are the 3 sub divisions of the peripheral nervous system
somatic
autonomic
enteric
describe the sensory and motor pathways of the somatic nervous system
sensory: somatic and special sense receptors to to CNS
motor: info from CNS to skeletal muscle
describe the sensory and motor pathways of the autonomic nervous system
sensory: receptors in visceral organs
motor: intro from CNS to cardiac and smooth muscle and glands
how is the autonomic nervous system divided
sympathetic and parasympathetic
describe the sensory and motor pathways of the enteric nervous system
sensory: motor chemical changes and stretch in GI tract
motor: innervates smooth muscle and glands and endocrine cells in GI tract
what are the 6 main structures of the neuron
cell body (soma)
dendrites
Axon
node of ranvier
Axon terminals
synaptic end bulb
what are the 3 types of neurons
multipolar neuron
bipolar
unipolar
what are the 6 types of neuroglia
astrocytes
oligodendrocytes
microglia
ependymal cells
Schwann cells
satellite cells
what are the 5 types of channels
leak channel
ligand-gated channel
mechanically-gated channel
voltage-gated channels
sodium-potassium pump
describe the leak channel
randomly open and close, letting ions specific to the channel to slowly leak in/out
describe the ligand-gated channel
open/close in response to a ligand/chemical; neurotransmitters, hormones, ions can be the stimulus for them to open/close
describe mechanically-gated channels
opens/closes due to mechanical stimulation such as vibrations, pressure on skin, stretch tissue
describe voltage-gated channels
open in response to voltage change
(open, inactive, close)
describe sodium-potassium pump
restoration and maintenance of resting membrane potential
describe the resting membrane potential
the summary of the amount of positive or negative ions on both the inside and outside of the cell
describe the graded potential
small deviation in resting membrane potential making it less or more polarised
describe summation
graded potentials added together, summating to create a bigger one
describe an action potential
sequence of rapidly occurring events that decrease or reverse membrane potential and restores it to resting state
describe what the threshold is
the summated membrane potential needs to meet this mark to create an action potential
describe the sequence of events for an AP with the voltage-gated channels
resting: Na and K channels closed.
depolarisation: Na channels open, Na moves into cell.
Depolarisation: Na channels inactivated. K channels open and move into cell.
Hyperpolarisation: Na channels closed. K channels still open and exiting cell.
Resting: Na and K channels closed. Na/K pumps restore resting potential
what are the two refactors periods of AP
absolute refractory period
relative refractory period
describe absolute refractory period
Na channels are already open so it can’t be open any further, and needs to close before opening again to start new AP
describe relative refractory period
second AP can occur but only by a larger than normal stimulus
what is propagation
AP in neurone must travel from where they arise in neuron to muscle or gland
what is continuous propagation
occurs in unmylinated axons; must occur in each segment of the axon
what is saltatory propagation
occurs in myelinated axons; the AP can “jump” over the myelin sheaths to the other nodes of ranvier - faster
what is a synapse
where neurons connect and communicate with each other
describe an electrical synapse
AP conducted directly between plasma memb of adjacent neurons through gap junctions. allows for fast communication and to be synchronised
describe a chemical synapse
pre and post synaptic cells are separated by synaptic cleft which is filled with interstitial fluid
what are the 7 steps of a chemical synapse
- AP arrives at axon terminal
- voltage gated Ca channels open
- Ca enters the cell
- Ca signals to vesicles
- vesicles move into the membrane
- docked vesicles release neurotransmitter by exocytosis
- neurotransmitter diffuses across the synaptic cleft and binds to receptors
what is the excitatory postsynaptic potential
a depolarising postsynaptic potential. brings the postsynaptic memb closer to threshold
what is the inhibitory postsynaptic potential
a hyperpolarising postsynaptic potential. takes thepostsynaptic memb further from threshold
what is the trigger zone
net summation of EPSPs and IPSPs determines whether an action potential is generated here
what are the three cranial meninges layerings
dura mater
arachnoid mater
pia mater
describe the blood-brain barrier
endothelial cells with tight junctions, a thicker basement memb and end-feet of astrocytes surround the capillaries of the brain - separates brain tissue from harmful substances in blood
describe the circle of willis
circular arrangement of interconnected arteries at the base of the brain to ensure a continuous supply of blood throughout the brain
describe cerebrospinal fluid
clear fluid that protects brain from chemical and physical injury
what is the pathway of CSF
lateral ventricle
third ventricle
fourth ventricle
central canal
subarachnoid space
outside of spinal cord and brain
back to Venus sinuses to be reabsorbed
what are the three parts of the brain stem
medulla oblongata
pons
midbrain
what are the four parts of the cerebrum
frontal lobe
parietal lobe
occipital lobe
temporal lobe
what are the three parts of the diencephalon
thalamus
hypothalamus
epithalamus