Nervous System and RMP Flashcards
Two types of nerves (origin wise) and where they come from
Cranial nerves (brain) and spinal nerves (spinal cord)
What is in the peripheral NS (anatomically)
Ganglia, cranial and spinal nerves
What are the two divisions of the PNS
Afferent (brings sensory information to the CNS)
Efferent (delivers motor commands from the CNS
1. Somatic NS - skeletal muscle (ones you can control)
2. Autonomic NS - smooth muscle, cardiac muscle and glands and adipose tissue (ones you can’t control)
Two types of cells in the nervous system
Neurons - send electrical signals through the NS (functional unit of the NS)
Neuroglia - supporting cells, isolate, much more than neurons inn numbers
Structure of a neuron
Soma (cell body), dendrites (receive information), axon (sends information) - axon hillock (where an action potential or electrical impulse starts) & axon terminals (release neurotransmitters t communicate with other cells)
Three types of neurons
Bipolar (soma in middle with an axon and and synaptic terminals on one end, dendrites on other end) rare and associated with special sensors such as vision (in retina) and smell (in olfactory system)
Unipolar - soma is to the side of axon with a small process. neuron is mostly axon with dendrites at the end. single fused process (dendrites and axon). mostly sensory neurons. axon hillock (where the action potential originates) is right up near the dendrites
Multipolar - stereotypical shape (one axon, more than two dendrites coming from the soma) many motor neurons are multipolar
Bundle of axons in the PNS
Nerves
Bundle of axons in the CNS
Tract
Cluster of neural cell bodies in the PNS and CNS
PNS - ganglia (ganglion singular)
CNS - nuclei
What are the two supporting cells (neuroglia) in the PNS
Satellite and Schwann cells
Neuroglia in the CNS
Oligodendrocytes
Astrocytes
Ependymal cells
Microglia
What supporting cells produce the myelin sheath
Schwann (PNS), Oligodendrocytes (CNS)
What does the myelin do
Increase the speed of the electrical conduction
Difference between myelination in CNS and PNS
Oligodendrocytes myelinated up to 60 cells, whereas Schwann cells only wrap around one axon
What is the RMP and what is its range in mV
A separation of opposite charge across the membrane of a cell, it can vary from -50 to -100 depending on the cell
Why is the body cell voltage negative?
the inside of the cell is negative compared to the outside
How is the body electrically neutral but there is still a voltage for every cell
There are an equal number of positively charged particles as negative in the body, the voltage occurs just at the membrane
When and how is a RMP established, what is it dependent on and how much is it for most neurons
When the concentration and electrical gradient of the ions is “balanced” or reached equilibrium so to speak.
Also dependent on the permeability of the ions through the membrane
-70mV
How does the cell maintain a concentration gradient after a while
via the sodium potassium pump which actively transports the ions against their concentration gradients
Q for lecturer - don’t the ions still maintain a concentration gradient due to the electrical gradient (eg. they go against their c gradient because they’re attracted to an opposite charge on the other side of the membrane)
…
What two cells can harvest (use) the energy provided/created by the RMP
How do they do it?
Neurons and muscle cells do it by changing the permeability of the plasma membrane to Na+ and K+ ions to alter the RMP
How do muscle cells and neurons create electrical signals
By craning the membrane potential by:
- changing membrane permeability to certain ions
- changing the number of open channels
