Axon potential, Muscle, Endocrine

Question 1

Flux

Answer 1

J = PdeltaC, units of mol/(cm^2*hr)

Question 2

Permeability coeff

Answer 2

P = KD/membrane thickness (X), units of cm/hr

Question 3

Partition coeff

Answer 3

K = solubility in oil : solubility in water

Question 4

P-type transporter

Answer 4

primary AT, E-P intermediate, Ex: Na/K ATPase, Ca ATPase, H/K ATPase

Question 5

F-type transporter

Answer 5

primary AT, H pump run in reverse to make ATP

Question 6

Cardiac glycosidases

Answer 6

Inhibits Na/K ATPase, ex: digoxin, digitoxin

Question 7

ABC transporters

Answer 7

primary AT, MDR and CFTR receptors

Question 8

Reflection coeff (sigma)

Answer 8

= 0 (permeable solute), = 1 (impermeable solute)

Question 9

Nernst equation

Answer 9

[-60/z]*log[Xi]/[Xo]

Question 10

GHK equation

Answer 10

[-60/z]*log(Pk[Ki]+PNa[Nai]+PCl[Clo)]/(Pk[Ko]+PNa[Nao]+PCl[Cli])

Question 11

Titin

Answer 11

connects Z-lines to thick filaments, runs from M-line to Z-line, provides horizontal stability

Question 12

Nebulin

Answer 12

Sets length of thin filaments to 1.05um, important for anchoring capping proteins

Question 13

Tropomodulin

Answer 13

actin capping protein, protects from depolymerization at one end

Question 14

CapZ

Answer 14

actin capping protein, protects from depolymerization at one end, anchors thin filament to Z-line proteins ie alpha-actinin

Question 15

Alpha-actinin

Answer 15

Anchors thin filaments to Z-line

Question 16

Thick filament

Answer 16

3 peptide chains, 1 heavy, 2 light, S1 (ATPase and actin binding site), S2 (neck), and tail region

Question 17

Thin filament

Answer 17

double stranded helix of actin monomers, with tropomyosin (extends over 7 actin filaments) and troponin (TnT, TnC, TnI)

Question 18

Cross bridge cycle

Answer 18

1) AM (rigor) myosin head bound to actin in 45deg angle
2) A + M-ATP, ATP binds and myosin head is released from actin in 45 deg angle
3) A + M-ADP-Pi, ATP is hydrolyzed, moves to 90deg angle, RESTING STATE
4) AM-ADP-Pi, myosin binds to actin IF Ca++ is present and has bound to TnC and moved tropomyosin out of the way, revealing actin binding site
5) AM, power stroke occurs when ADP-Pi leaves

Question 19

Isotonic

Answer 19

Same force, myosin detaches and binds to DIFFERENT actin molecule, shortening occurs

Question 20

Isometric

Answer 20

Same length, myosin detaches and binds to SAME actin molecule, force is generated

Question 21

Striated muscle is always turned ?

Answer 21

ON! only inhibited by troponin/tropomyosis, turned on when Ca++ binds to TnC of troponin, this is disinhibition

Question 22

T-tubules

Answer 22

Extracellular tubular system on invaginations of sarcolemma

Question 23

Sarcoplasmic reticulum

Answer 23

Intracellular tubular system which stores Ca++, has longitudinal part with Ca++ ATPase and terminal cisternea which stores Ca-calsequestrin

Question 24

Contraction in skeletal muscle

Answer 24

DHR act as voltage-sensor proteins and move foot processes our of the way so RYR can release Ca++ from SR, muscle relaxes through Ca++ ATPase in longitudinal SR which pumps Ca++ out of the cytosol into SR, no extracellular Ca++, contraction is all or none

Question 25

Contraction in cardiac muscle

Answer 25

DHR act as voltage-gated calcium channels and respond to AP by letting a little Ca++ into the cell which triggers Ca++ release from the SR via the RYR - Calcium induced calcium release, need both Ca++ ATP for SR and Na/Ca exchanger (secondary AT) to remove Ca++ from the cytosol, contraction is graded, through prolonging plateau phase

Question 26

PKA effects in cardiac muscle

Answer 26

1) phosphorylates TnI, increasing relaxation, and decreasing TnC affinity for Ca++
2) phosphorylates phospholamban on SR that increases CaATPase activity, increasing relaxation

Question 27

Force production in skeletal muscle is controlled by what?

Answer 27

Neural control

Question 28

How is skeletal muscle graded

Answer 28

Twitch, summation of force (repeated APs), tetanus (repetitive stimulation, rarely occurs physiologically)

Question 29

Henneman Size Principle

Answer 29

recruitment of motor units within a muscle takes place with recruitment of larger and larger motor units