Ch 12-13

Question 1

compare and contrast the nervous and endocrine systems

Answer 1

nervous
• fast
• short response
•neurotransmitters
• acts at specific locations
• act over short distances

endocrine
• slow
• longer response
• hormones
• diffuses / widespread
• act over long distances

BOTH:
- specialized for control and coordination

Question 2

what are neurons and their 4 functional properties

Answer 2

functional unit of the nervous system
- morphology varies

1. input (dendrites)
2. integration of potentials (soma/ cell body)
3. conduction (axon)
4. output (presynaptic terminals)

Question 3

3 structural classifications of neurons and most are what

Answer 3

based on # of things extending from cell body

• unipolar (touch)
• bipolar (eyes, ears)
• multipolar

most are multipolar !

Question 4

3 functional classifications of neurons and where they are found

Answer 4

1. sensory (afferent) (in)
   - from PNS to CNS
2. interneurons (association neurons)
   - only in CNS, between sensory and motor
3. motor (efferent) (away)
   - from CNS thru PNS to effectors

Question 5

what are the supporting cells of neurons in the CNS and PNS

Answer 5

glial cells

in CNS
- astrocyte
- microglial cell
- oligodendrocyte

in PNS
- schwann cell

Question 6

what is membrane potential

Answer 6

voltage that exists across the plasma membrane
- unstimulated cells have a resting membrane potential ~ 70 mv but varies within cells

Question 7

inside and outside of cell electrically _____
but across membrane ___ _____

Answer 7

neutral

across membrane not neutral!

Question 8

ohms law

Answer 8

I = V / R

Question 9

what causes changes in membrane permeability

Answer 9

ion channels

Question 10

ligand gated ion channels

Answer 10

opens and closes in response to a specific chemical stimulus

Question 11

mechanically gated ion channels

Answer 11

open or close in response to mechanical stimulation (touch, pressure)

Question 12

voltage gated ion channel

Answer 12

opens in response to a change in membrane potential

Question 13

where is K higher ? where is Na higher ?

Answer 13

K+ higher inside & A/P/S-
Na+ / Cl- higher outside

Question 14

what has more leak channels and dictates RMP more?

Answer 14

K+

Question 15

what is a graded potential and 2 types

Answer 15

small deviation from resting membrane potential
* weakens as gets father away from stimulus

• depolarizing
  = bump up (less negative)
• hyperpolarizing
  = bump down (more negative)

Question 16

main difference between action potentials and graded potentials

Answer 16

action:
NOT influenced by stimulus strength

graded:
influenced by stimulus strength

Question 17

what can trigger graded potentials

Answer 17

• neurotransmitters (ligand gated ion channels)
• mechanical deformation (mechanically gated ion channels)
• light energy via photoreceptor cells

Question 18

what is better to be used for long distance travel graded or action potentials

Answer 18

action!

Question 19

graded potentials can _____ at the ___ ____ to trigger an action potential

Answer 19

can summate at the axon hillock

Question 20

3 phases of an action potential and describe

Answer 20

1. depolarizing (rising)
   - opened VG Na channels
   - lots of Na move in!
2. repolarizing (falling)
   - VG Na channels inactived
   - at peak open VG K+ channel
   - K+ move out of cell
3. hyperpolarizing (recovery)
   - K+ channels are slow to close so cause hyperpolarization
   - VG Na+ closed

Question 21

what is threshold mv

Answer 21

-55mv

Question 22

what is a suprathreshold stimulus

Answer 22

stronger than necessary
- prolonged time = multiple signals (higher frequency)

amplitude stays the SAME

Question 23

what is spatial summation

Answer 23

graded potentials from DIFFERENT sites add together @ axon hillock to create a.p if both are depolarizing

Question 24

what is temporal summation

Answer 24

graded potentials from same site but with increased frequency of stimuli summate

Question 25

what is the conduction of action potentials influenced by? (3) and describe

Answer 25

1. axon diameter • conduction velocity increases with larger diameter 2. myelination of axon • provides electrical insulation (no leakage of charge) + increases speed of conduction CNS = oligodendrocyte PNS = shwann cell 3. temperature • as temp increases so does velocity as increasing ion movement

Question 26

sultitory vs continuous conduction

Answer 26

sultitory - A.P propagated from one node to another (myelinated) continuous - unmyelinated

Question 27

what does the node of Ranvier contain

Answer 27

it is packed with VG Na+ and K+ channels

Question 28

what is a synapse and the 2 types

Answer 28

= point at which one neuron communicates with another neuron or a target tissue - electrical - chemical

Question 29

electrical synapse

Answer 29

bidirectional !! can go from pre to post synaptic neurons and vice versa • must be very close together • have gap junctions • coupling potential

Question 30

chemical synapses

Answer 30

unidirectional !! move neurotransmitters in synaptic vesicles from pre to post synaptic neuron • graded potentials at neurotransmitter receptors • has post synaptic potential

Question 31

2 types of neurotransmitters

Answer 31

excitatory or inhibitory EPSPs (depolarizing to reach threshold) or IPSPs (hyperpolarizing) acetylcholine = excitatory

Question 32

describe what happens in a chemical synapse (4 steps)

Answer 32

1. electrical stimulus (action potential) 2. VG calcium channel opens/ activated and Ca+ flows into cell(axon terminal) 3. triggers calcium induced exocytosis - synaptic vesicles with neurotransmitters release into synaptic cleft & diffuse 4. neurotransmitters bind to receptors on post synaptic neuron

Question 33

what are the 2 options for neurotransmitters when they reach the post synaptic neuron

Answer 33

1. ionotropic synapse • fast • ion channels open • more Na+ in ! so depolarizing • end plate potential to a graded potential (muscular) 2. metabotropic synapse • slow • linked with G protein • trigger intracellular signalling

Question 34

is a graded potential (one of) large enough to depolarize a muscle fiber

Answer 34

no one is not large enough