Module 3- Neurophysiology

Question 1

Central Nervous System

Answer 1

acts as the integrating system
-brain and spinal cord

Question 2

Peripheral Nervous System

Answer 2

-rapid communication
(1) Sensory division of the PNS; sends info to the CNS through afferent (sensory) neurons
(2) Efferent division of PNS; takes info from the CNS to target cells via efferent neurons

Question 3

Efferent neurons

Answer 3

(1) autonomic neurons; sympathetic and parasympathetic
(2) somatic motor neurons

Question 4

autonomic neurons

Answer 4

• unconscious, homeostatic response
  sympathetic and parasympathetic
• controls: cardiac muscle, smooth muscle, exocrine glands/cells, some adipose tissue

Question 5

somatic motor neurons

Answer 5

-conscious movement
controls skeletal muscle

Question 6

interneurons

Answer 6

neurons entirely within the CNS

Question 7

ganglia

Answer 7

clusters of neuron cell bodies in the peripheral nervous system

Question 8

nerves

Answer 8

bundles of axons in the peripheral nervous system
-transmits signals between brain or spinal cord and other body regions

Question 9

Autonomic (involuntary) nervous system

Answer 9

-conveys impulses from CNS to smooth muscle, cardiac muscle, and glands
- 1st preganglionic fiber has cell body in the CNS and synapses with 2nd in the autonomic ganglion
-2nd postganglionic fiber sends signal from autonomic ganglion to the effector organ

Question 10

spinal cord

Answer 10

-links brain and PNS
-controls some involuntary functions
-protected by vertebral column
- 31 pairs of spinal nerves

Question 11

sympathetic

Answer 11

-fight or flight
-excitement, emergency, exercise, embarrassment
-routes energy resources to brain, heart, and skeletal muscles

Question 12

sympathetic effects

Answer 12

-adrenergic effects
-dilates pupils
-increases heart beat and force of contraction
- relaxes airways
-inhibition of digestion and stomach activity
-stimulates release of glucose into the blood; inhibits insulin release from pancreas
-stimulates secretion of epinephrine and norepinephrine from adrenal

Question 13

parasympathetic

Answer 13

-rest and digest
-digestion, defecation, and dieresis
-reduces energy use and directs “housekeeping” activities

Question 14

parasympathetic effects

Answer 14

• cholinergic
  constricts pupils
• slows heartbeat
  -constricts airways
  -stimulates digestion and stomach activity
  -increases glucose utilization by liver cells; stimulates insulin secretion from pancreas

Question 15

sympathetic fibers

Answer 15

the sympathetic nervous system has short cholingeric (acetlycholine-releasing) preganglionic fibers and long adrenergic (norepinephrine-releasing) postganglionic fibers

Question 16

parasympathetic fibers

Answer 16

parasympathetic nervous system has long cholinergic preganglionic fibers and short cholinergic postganglionic fibers

Question 17

long distance communication

Answer 17

the nervous system achieves long distance communication by combining long distances electrical signals within (along) cells and short distance chemical signals between cells (synapses)

Question 18

neuron structure

Answer 18

cell body: organelles
dendrites; receive signals
axon; transmits signals
axon hillock; initiates signals to travel down axon

Question 19

membrane potential

Answer 19

unequal distribution of positivities and negative charges across the membrane
-in neurons, is primarily driven by the distribution of sodium and potassium ions

Question 20

resting membrane

Answer 20

the membrane potential of cell (neuron) not transmitting signals; roughly -70 mV, polarized, negative

Question 21

leaky channel

Answer 21

always open, no gate and not regulated

Question 22

ligand (chemically) gated

Answer 22

open in response to a specific chemical (such as a neurotransmitter)

Question 23

mechanical gated

Answer 23

open in response to physical deformation of the receptor

Question 24

voltage gated

Answer 24

only open in response to specific electrical signals

Question 25

depolarization

Answer 25

- closer to 0mV -decrease in potential; membrane less negative

Question 26

repolarization

Answer 26

return to resting potential after depolarization

Question 27

hyper polarization

Answer 27

-further from 0mV increase in potential; membrane more negative

Question 28

graded potentials overview

Answer 28

-occur in dendrites and cell body -small, localized change in membrane potential

Question 29

graded potential

Answer 29

-the magnitude of change in membrane potential varies with strength of stimulus (greater stimulus = more gated channels open) -caused by opening of voltage or ligand gates ion channels -local signal initiated in dendrites, decays with distance

Question 30

graded potential effects

Answer 30

can cause depolarization or hyperpolarization -depolarization; increase in membrane potential, more Na+ diffuses into the cell - hyperpolarization; decrease in membrane potential, more K+ diffuses out of cell

Question 31

action potentials

Answer 31

-brief, rapid reversal of membrane potential -begins at the axon hillock, travels down axon (conduction) -all to none threshold -initiated by graded potentials

Question 32

action potential phases summary

Answer 32

1. resting potential (Na+/K+ pump) 2. depolarization (Voltage gated Na+ channel) 3. depolarization (Voltage gates K+ channel) 4. Resting potential (Na+/K+ pump)

Question 33

electrical synapses

Answer 33

- electrical current flows from one cell to next via gap junctions direct; gap junctions; ion flow [CNS: sensory cells to neurons; in btwn cardiac cells; neuron to "non-excitable" effectors (e.g. adrenal medulla)]

Question 34

chemical synapses

Answer 34

-chemical neurotransmitter released from presynaptic neuron indirect; synaptic cleft; neurotransmitters [PNS; MOST common; neuron to neuron; neuron to "excitable" effectors (e.g. muscles)]

Question 35

neurotransmitter receptors are grouped into two major types

Answer 35

(1) ionotropic receptors - ligand-gated ion channels -fast response -result in change in Vm (2) metabotropic receptors -g protein coupled receptors -slower response -can result in Vm -can result in long term changes in gene expression

Question 36

three major drivers of resting membrane potential

Answer 36

(1) sodium-potassium pump (2) leaky ion channels (3) cellular proteins leads to.. -more Na+ outside -more K+ inside