1.5 Phys Must Knows

Question 1

Name ligand receptors with tyrosine kinase activity?

Answer 1

*insulin, epidermal GF and fibroblast GF

Question 2

what is JAK/STAT pathway?

Answer 2

JAK is a membrane transduction pathway

*in this case, the receptor doesn’t have an enzymatic subunit but it is closely related to phosphorylation of STAT

Question 3

the degree of cell electronegativity is dictated by?

Answer 3

cell type and cell size

• large motor skelelal/cardiac muscle = -90mV
• small nerves/CNS/smooth muscle = -40 to -60mV
• RBCs= -10 to -20

Question 4

Big point of opening K+ channels (equilibrium potential for K+)

Answer 4

open K channels, K leaves cell (EFFLUX)nand membrane charge races to -94 (which is equilibrium potential for K)
*this is where the chemical conc gradient from inside to outside is equal to and opposite of the electrical gradient which is 0mV on outside and now -94 inside

Question 5

No efflux of moleules when their channels are open indicates?

Answer 5

electronegative equalibrium
(Ex: once cell membrane reaches -94 for K, it’s so negative that it’ll refuse to let K+ leave anymore – opposites attrack)

Question 6

what is equilibirum potential for K+? for Na+?

Answer 6

K+ = -94 (will hyperpolarize; inhibitory)
Na+ = +61 (will depolarize; excitatory)

Question 7

Big point of opening Na+ channels (equilibrium potential for Na+)

Answer 7

Na INFLUXES (rushes inside cell)
*as the membrane races towards +61 and the inside of the cell becomes more electropositive, it eventually REPELS any further + charge from entering

Question 8

Big point about equilibrium potentials?

Answer 8

for any molecule, it only tells you what the membrane charge is going to race towards, does NOT mean it will get there

Question 9

EPSP?

Answer 9

excitatory post-synaptic potentials are GRADED

• drives axon hillock closer to threshold (depolarize)
• makes nearuon more excitable

Question 10

IPSP?

Answer 10

inhibitory post-synaptic potentials are GRADED

• drive axon hillock AWAY from threshold (hyperpolerize)
• makes neurons less excitalbe

Question 11

Example of EPSP?

Answer 11

1) Ach binds onto receptor
2) Na+ pores OPEN (influx)
3) membrane depolarizes/excited/towards threshold
* ** can also be ligand that CLOSES K or CL

Question 12

Example of IPSP?

Answer 12

1) ligand binds on post-synaptic membrane
2) causes K+ or Cl- channels to open
3) K+ = EFFLUX; Cl- = influx
4) membrane hyperpolarizes/UNexcited/away from threshold

Question 13

describe depolarization, overshoot, repolarization, hyperpolarization and stimulation for A and G potentials?

Answer 13

• depolarization= line goes up towards negative
• oveshoot= line bypasses 0mV
• repolarization= line descends back to resting poten.
• hyperpolarization= line dips below resting, more -
• stimulation= NOT continuous, an event

Question 14

Local anesthetic blocks?

*Ex of local?

Answer 14

blocks sodium channels, so dendrites and cell bodies unaffected
*lidocaine

Question 15

two types of stimulus in action and graded potentials? What dependent on stimulus?

Answer 15

inhibitory= hyperpolarization (K+)
excitatory= depolarization (Na+)
**amplitude of GRADED potentials are modulated by stimulus strength

Question 16

location of graded and action potentials?

Answer 16

graded= dendrites/cell body with ligand gates
action= axon with voltage gates

Question 17

temportal vs spatial summation?

which one has greater stimulation?

Answer 17

• temporal= over time with 1 stimulating force happening multiple times
• spatial summation= multple stimulating events coming from different places at same time great stimulation

Question 18

mylinated vs unmyelinated nerves?

Answer 18

*Myelinated= nerve conduction velocity 5-50X greater, decreases energy requirment for conduction, better nerve generation, BUT takes more energy to form myelinated nerves, take longer to numb

Question 19

characteristic of graded vs action potentials?

Answer 19

• action= all-or-not; MUST meet threshold, have refractory periods; NO Summation
• graded= opposite

Question 20

Absolute refractory period (ARP) ENDS and relative refractory period (RRP) begins with?

Answer 20

opening of H gate

Question 21

when does threshold vary for action potentials?

Answer 21

during refractory periods

Question 22

Na+ channel gating: at rest? at threshold? reaching depolarization? membrane repolarization?

Answer 22

• at rest= m activation gate is closed; h inactivation gate open
• at threshold= m activation gate opens and Na+ flows in BEGINNING ARP
• depolarization= h gate closes
• repolarization= m gate closes and THEN h gate reopens (end ARP/begin RRP) *microsencond they are both closed**

Question 23

K+ channel gating?

Answer 23

• at rest n gate is closed
• as membrane depolarizs to overshoot, n gate open allowing EFFLUX and repolarization
• when resting is restored the n gate closes

Question 24

hypoatremia

Answer 24

a condition of low blood sodium (can be caused by water intoxication aka too much water)
*neural dysfunction, heart’kidney imparment, sluggish, negative storke test

Question 25

what keep impulses from reversing on axon?

Answer 25

1) the absolute refractory period

Question 26

What are the mylinating cells in PNS and CNS?

Answer 26

schwann cells= PNS

oligodendoglia cells= CNS

Question 27

salatory conduction

Answer 27

when action potentials occur only at the nodes on myelinated axon

Question 28

multiple sclerosis?

Answer 28

autoimmune attack on and degradation of myelin sheath

Bad bc 1) prevents regrowth of myelin 2) poor insulator 3) nerve disfuntion/motor loss

Question 29

7 synaptic steps at terminal?

Answer 29

1) membrane depolarizes
2) Ca+ influx thru gated channels
3) Ca+ activation of calmodulin
4) calmodulin activation of protein kinase
5) protein kinase activation of synapsin to move synaptic vesicle to surface
6) exocytosis of synaptic vesicles
7) release of neurotransmitters

Question 30

presynaptic inhibition? usually used?

• inhibition of an excitatory PS neuron=
• *inhibition of an inhibitory PS neuron=

(this is special circumstance)

Answer 30

PS inhibition nuerons usually release GABA neuromodulator at nerve terminal of PS; GABA then opens CL channels on PS which prevents neurotransmitter release from PS

• inhibition of an excitatory PS neuron= Postsynaptic INhibition
• *inhibition of an inhibitory PS neuron= Postsynaptic excitation

Question 31

facilitation of neurons?

Answer 31

some neuropeptides can regulate long-term membrane permeability for select ions by “re-setting” resting membrane potentials
*if re-set to a potential that is near threshold, it is said to be facilitated and can generate action potentials/excitation more easily

Question 32

defacilitation of neurons is?

Answer 32

harder to activate pathways

*probably “re-set” ion far away from threshold

Question 33

1) metbolic alkalosis=
2) metabolic acidosis=
3) central hypoxia=
4) caffeine=
5) most aneathetics

Answer 33

1) increase excitability; seizures
2) increase excitability; coma
3) decrease excitability; unconsciousness
4) increase excitability
5) decrease excitability

Question 34

agonists vs antagonists

Answer 34

Agonists= a ligand that can bind to another receptor & activate a similar cellular response but NOT to the same degree
Antagonist= has affinity and can bind but has no acitvation cite so it WON'T produce cellular activity