NS I - Nervous System Overview and Action Potentials

Question 1

what are the overall functions of the nervous system

Answer 1

-muscle contraction
-integration of blood oxygen, carbon dioxide, and pH levels via respiratory activity
- regulation of volumes and pressures in the circulation via cardiovascular and urinary function
-digestive system motility and secretion

Question 2

whats the difference between nervous system reflex and an endocrine system reflex

Answer 2

nervous system is quick fix and ES is slower long term maintenance

Question 3

what is the functional unit of the NS

Answer 3

neurons

Question 4

what are the two main divisions of the NS

Answer 4

afferent and efferent

Question 5

what are the parts of the afferent NS

Answer 5

visceral and somatic

Question 6

what are the parts of the efferent NS

Answer 6

somatic and autonomic

Question 7

what are nissl bodies

Answer 7

clusters of ribosomes on neurons that make the cell body and tissue appear gray

Question 8

what are internodes formed by

Answer 8

neuroglia cells such as oligodendrocytes (CNS) and Schwann cells (PNS)

Question 9

what are internodes separated by

Answer 9

nodes of ranvier

Question 10

what is the function of internodes

Answer 10

speed up the rate of nerve impulse conduction

Question 11

which way does information flow in a neuron

Answer 11

from the cell body down the axon

Question 12

what type of neurons are sensory neurons and where are they found

Answer 12

pseudounipolar and bipolar neurons found in afferent division of PNS

Question 13

what do sensory neurons do

Answer 13

carry sensory information from reflex receptor to CNS

Question 14

are sensory neurons myelinated

Answer 14

yes

Question 15

what type of neurons are motor neurons and where are they found

Answer 15

multipolar neurons found in the efferent division of the PNS

Question 16

where are cell bodies and dendrites of sensory neurons found

Answer 16

PNS with axons that extend into the CNS

Question 17

what do motor neurons do

Answer 17

carry motor commands from CNS to effectors

Question 18

where are the cell bodies/dendrites of motor neurons found

Answer 18

in CNS axons extend into PNS

Question 19

what types of neurons are interneurons and where are they found

Answer 19

multipolar, anaxonic, found in the CNS only

Question 20

what do interneurons do

Answer 20

carry information from one neuron to another

Question 21

where are APs trigggered

Answer 21

at the axon hillock

Question 22

what are graded potentials

Answer 22

small changes in membrane potential of variable strength/amplitude

Question 23

whats the difference between graded potentials and APs

Answer 23

GPs last longer but only travel a short distance along membrane and lose strength as they travel

Question 24

what are examples of graded potentials

Answer 24

-synaptic potentials
-EPSPs
-IPSPs

Question 25

are receptor potentials excitatory or inhibitory

Answer 25

excitatory

Question 26

are end plate potentials excitatory or inhibitory

Answer 26

excitatory

Question 27

whats happening in depolarization

Answer 27

Na+ moves into the cell through VG Na+ channels
then VG Na+ channels close and slow VG K+ channels open

Question 28

what happens during repolarization

Answer 28

K+ moves outside the cell through VG K+ channels

Question 29

what happens during hyperpolarization

Answer 29

VG K+ channels still open then they close and return to resting membrane potential

Question 30

what causes the absolute refractory period

Answer 30

the all or non activation and the voltage gated Na+ channels closed inactivation gates

Question 31

what causes the relative refractory period

Answer 31

some sodium channels resetting to resting state after hyperpolarization

Question 32

what would a potassium concentration between 3.5 mM and 6 mM do to a neuron

Answer 32

-increase membrane excitability
-depolarizes membrane moving closer to threshold

Question 33

what would a potassium concentration greater than 6 mM do to a neuron

Answer 33

-reduce membrane excitability
-depolarizes membrane and cause inactivation of VG Na+ channels

Question 34

what does hypokalemia do to to neuron excitability

Answer 34

reduces membrane excitability and hyperpolarizes membrane

Question 35

what does hypercalcemia do to membranes

Answer 35

reduces membrane excitability

Question 36

what does hypocalcemia do to membranes

Answer 36

increased membrane excitability

Question 37

what is threshold potential

Answer 37

the Vm at which AP triggered which is usually around -50 mV

Question 38

whats the difference between VG Na+ channels and VG K+ channels

Answer 38

sodium channels have an activation gate and an inactivation gate. potassium channels only have an inactivation gate

Question 39

describe the process of generating an AP and local current flow

Answer 39

-a graded potential above threshold reaches the trigger zone
- VG Na+ channels open and Na+ enters the axon
- positive charge flows into adjacent sections of the axon by local current flow
- local current flow from the active region causes new sections of the membrane to depolarize
-the refractory period prevents backward conduction. loss of K+ from the cytoplasm repolarizes the membrane

Question 40

what are the 2 ways to increase conduction velocity of AP

Answer 40

-if myelinated
-increasing axonal diameter

Question 41

what is saltatory conduction

Answer 41

AP jumps from node to node