Chapter 11 - fundamental's of the nervous system and tissue Flashcards
Define and match nucleus, tract, ganglion, and nerve to CNS and PNS.
CNS - nucleus(cell body) and tract (axons)
PNS - ganglion (cell body) and nerve (axons)
What is the difference between retrograde and anterograde?
R - movement toward the cell body (backwards)
- viruses, bacteria, degrade organelles
A - movement away from cell body (forward)
How do certain viruses damage neurons?
By using retrograde they are able to enter the cell
- polio, rabies, herpes
where does AP vs GP happen?
A - axon
G - cell body (soma), dendrites, axon hillock
What is a myelin sheath and its function?
white, fatty substance used to insulate and increase speed of nerve impulses
Explain the difference between myelin sheaths in the CNS and PNS.
- thin fibers don’t have myelination
CNS - oligodendrocytes - can wrap around 60 axons
PNS - Schwann cells
What is voltage?
a measure of potential energy generated by separated charge
What is current?
flow of electrical charge (ions) between two points
What is resistance and the 2 types?
hindrance to charge flow
insulator: substance with high electrical resistance
conductor: substance with low electrical resistance
What are the 2 types of ion channels?
leakage (non gated) channel: always open
chemically gated channel: opens only with bonded chemical
voltage-gated channel: open and close in response to changes in membrane potential
mechanically gated channels: open and clos in response to physical deformation of receptors
what is difference between conc. gradient and electrical gradient?
C - ions move from area of high to low concentration
E - ions move towards area of opposite electrical charge
What is the voltage of the membrane at rest and the range of the actual voltage?
RMP - -70mV
Range - -40mV to -90mV
explain 4 key points in the plasma membrane permeability.
- impermeable to large anionic proteins
- slightly permeable to Na+
- very permeable to K+
- quite permeable to Cl-
Explain the difference between graded and action potential.
GP- short lived and localized in membrane potential
- the more stimulus, the more voltage gates open, the father the current flows
receptor potential: graded potential in receptors of sensory neurons
postsynaptic potential: neuron graded potential
end-plate potential: occurs in muscle cells
AP- goes from -70mV to +30mV
- occurs in excitable membranes
Explain the difference between depolarization, repolarization and hyperpolarization.
D - Sodium channels open, allowing Sodium ion entry. This corresponds to an increasing part of the graph.
R - Sodium channels are being inactivated. Potassium channels open, allowing potassium ions to exit. This corresponds to the decreasing part of the graph.
H - Some potassium channels remain open. Sodium channels reset. This corresponds to the minimum and then increases back to the resting part of the graph.
What are the 2 types of Na+ channels?
Activation gates: closed at rest; open with depolarization; Na+ enters
Inactivation gates: open at rest; block channel once it is open to prevent more Na+ from entering
What is propagation?
Propagation allows A P to be transmitted from origin down entire axon length toward terminals
- causes depolarization to move to the adjacent membrane
What determines the stimulus intensity?
- frequency is number of impulses (AP) received per second
- higher frequencies means stronger stimulus
What is the difference between absolute and relative refractory periods?
ARP - time from opening of Na+ channels until resetting of the channels
- enforces one-way transmission of APs
RRP- Na+ channels returned to their resting state, some K+ channels still open
- only very strong stimulus can cause AP
What are the two factors AP propagation depends on?
Axon diameter - larger means less resistant, so faster impulse conduction
Degree of myelination - more means faster
AP can propagate in 2 ways.
Nonmyelinated axons: slower conduction called continuous conduction
Myelinated axon: faster conduction called saltatory conduction
What are the 5 types of synaptic connections?
axodendritic: between axon terminal and dendrite
axosomatic: between axon and soma
axoaxonal: between axon and axon
dendrodendritic - dendrite and dendrite
somatodendritic - soma and dendrite
What are the 2 parts of the chemical synapses?
axon terminal: presynaptic neuron contains synaptic vesicles with neurotransmitters
receptor region: postsynaptic neurons receive neurotransmitter
What is the difference between EPSP and IPSP?
EPSP - Depolarization that spreads to initial segment of axon; moves membrane potential toward threshold for generating an AP
IPSP - Hyperpolarization that spreads to initial segment of axon; moves membrane potential away from threshold for generating an AP.
What are the 2 types of summation by the postsynaptic neuron?
Temporal summation: one or more presynaptic neurons transmit impulses in rapid-fire order
Spatial summation: postsynaptic neuron is stimulated by large number of terminals simultaneously
Explain biogenic amines.
catecholamines - dopamine, norepinephrine and epinephrine
indolamines - serotonin and histamine
Explain Acetylcholine.
- released at neuromuscular junctions
- block nerve causes spasms
explain amino acids.
- glutamate, aspartate, glycine, GABA
explain peptides (neuropeptides).
substance P (mediator of pain signals)
endorphins (reduces pain perception)
Gut-brain peptides ( regulating digestion)
explain gas and lipid transmitters
gasotransmitters (binds to g proteins)
endocannabinoids (involved in learning and memory)
How is potential generated?
- difference in ionic composition of ICF and ECF
- difference in plasma membrane permeability
Examples of purines.
ATP and adenosine
