Chapter 11 - fundamental's of the nervous system and tissue

Question 1

Define and match nucleus, tract, ganglion, and nerve to CNS and PNS.

Answer 1

CNS - nucleus(cell body) and tract (axons)
PNS - ganglion (cell body) and nerve (axons)

Question 2

What is the difference between retrograde and anterograde?

Answer 2

R - movement toward the cell body (backwards)
- viruses, bacteria, degrade organelles
A - movement away from cell body (forward)

Question 3

How do certain viruses damage neurons?

Answer 3

By using retrograde they are able to enter the cell
- polio, rabies, herpes

Question 4

where does AP vs GP happen?

Answer 4

A - axon
G - cell body (soma), dendrites, axon hillock

Question 5

What is a myelin sheath and its function?

Answer 5

white, fatty substance used to insulate and increase speed of nerve impulses

Question 6

Explain the difference between myelin sheaths in the CNS and PNS.

Answer 6

• thin fibers don’t have myelination
  CNS - oligodendrocytes - can wrap around 60 axons

PNS - Schwann cells

Question 7

What is voltage?

Answer 7

a measure of potential energy generated by separated charge

Question 8

What is current?

Answer 8

flow of electrical charge (ions) between two points

Question 9

What is resistance and the 2 types?

Answer 9

hindrance to charge flow

insulator: substance with high electrical resistance
conductor: substance with low electrical resistance

Question 10

What are the 2 types of ion channels?

Answer 10

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

Question 11

what is difference between conc. gradient and electrical gradient?

Answer 11

C - ions move from area of high to low concentration
E - ions move towards area of opposite electrical charge

Question 12

What is the voltage of the membrane at rest and the range of the actual voltage?

Answer 12

RMP - -70mV
Range - -40mV to -90mV

Question 13

explain 4 key points in the plasma membrane permeability.

Answer 13

• impermeable to large anionic proteins
• slightly permeable to Na+
• very permeable to K+
• quite permeable to Cl-

Question 14

Explain the difference between graded and action potential.

Answer 14

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

Question 15

Explain the difference between depolarization, repolarization and hyperpolarization.

Answer 15

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.

Question 16

What are the 2 types of Na+ channels?

Answer 16

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

Question 17

What is propagation?

Answer 17

Propagation allows A P to be transmitted from origin down entire axon length toward terminals
- causes depolarization to move to the adjacent membrane

Question 18

What determines the stimulus intensity?

Answer 18

• frequency is number of impulses (AP) received per second
• higher frequencies means stronger stimulus

Question 19

What is the difference between absolute and relative refractory periods?

Answer 19

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

Question 20

What are the two factors AP propagation depends on?

Answer 20

Axon diameter - larger means less resistant, so faster impulse conduction

Degree of myelination - more means faster

Question 21

AP can propagate in 2 ways.

Answer 21

Nonmyelinated axons: slower conduction called continuous conduction

Myelinated axon: faster conduction called saltatory conduction

Question 22

What are the 5 types of synaptic connections?

Answer 22

axodendritic: between axon terminal and dendrite

axosomatic: between axon and soma

axoaxonal: between axon and axon

dendrodendritic - dendrite and dendrite

somatodendritic - soma and dendrite

Question 23

What are the 2 parts of the chemical synapses?

Answer 23

axon terminal: presynaptic neuron contains synaptic vesicles with neurotransmitters

receptor region: postsynaptic neurons receive neurotransmitter

Question 24

What is the difference between EPSP and IPSP?

Answer 24

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.

Question 25

What are the 2 types of summation by the postsynaptic neuron?

Answer 25

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

Question 26

Explain biogenic amines.

Answer 26

catecholamines - dopamine, norepinephrine and epinephrine

indolamines - serotonin and histamine

Question 26

Explain Acetylcholine.

Answer 26

• released at neuromuscular junctions
• block nerve causes spasms

Question 27

explain amino acids.

Answer 27

• glutamate, aspartate, glycine, GABA

Question 28

explain peptides (neuropeptides).

Answer 28

substance P (mediator of pain signals)
endorphins (reduces pain perception)
Gut-brain peptides ( regulating digestion)

Question 29

explain gas and lipid transmitters

Answer 29

gasotransmitters (binds to g proteins)

endocannabinoids (involved in learning and memory)

Question 30

How is potential generated?

Answer 30

• difference in ionic composition of ICF and ECF
• difference in plasma membrane permeability

Question 31

Examples of purines.

Answer 31

ATP and adenosine