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SN Physiology Final > Cardiovascular > Flashcards

Cardiovascular Flashcards

1
Q

define stressed volume?

A

volume of blood contained in the arteries

arteries are under the highest pressure in the vasculature

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2
Q

where can we find the highest resistance to blood flow?

why?

A

Arterioles

they have a lot of smooth muscle which is tonically active (innervated by sympathetic adrenergic nerve fibers)

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3
Q

what adrenergic R can we find in the arterioles in the skin and splanchnic vasculature?
what is the consequences?

A

a1-Adrenergic -> contraction -> decrease in diameter of the arteriole -> increase the resistance to blood flow

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4
Q

which vessels have large capacitance and why?

A

veins

bcs their walls contain much less elastic tissue than arteries

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5
Q

equation for the relationship btw velosity, flow and crossectional area

A

V=Q/A

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6
Q

what two factors eefect the blood flow through a blood vessel?

A
  1. pressure difference

2. resistance of the vessel

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7
Q

equation for the relationship btw flow, pressure and resistance?

A

Q=P/R

mL/min

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8
Q

direction of blood flow is allways from:

A

high pressure to low pressure

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9
Q

what will higher resistance do to flow?

A

inversley prop. higher resistance -> decreased flow

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10
Q

define TPR

A

the resistance of the entire systemic vasculature

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11
Q

how can we measure TPR?

A

we can put cardiac output instead of flow in the Q=P/R equation
and the difference in pressure btw Aorta and Vena Cava

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12
Q

what does compliance describes?

A

the volume of blood the vessel can hold at a given pressure

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13
Q

compliance equation

A

C=V/P
C- Compliance (mL/mmHg)
V- Volume (mL)
P- Pressure (mmHg)

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14
Q

SA node BPM

A

60-80 BPM

sinus rythm

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15
Q

what is the reason for the delay 0.1 sec in the AV node conduction?

A
  1. less amount of Gap Junction

2. diameter is smaller (slower conductance)

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16
Q

connection btw nodal cells

A

Gap Junction

17
Q

funny channels function

A

allow slow leaking into the cell of Na+

18
Q

resting membrane potential of nodal cells

A

around -60 mV

19
Q

T-type channels are for ___ and open at ___

A

Ca++

-55 mV

20
Q

threshold point in the nodal cells

A

-40 mV

21
Q

which channel opens when the membrane otential reaches the threshold?

A

L-type Ca++ channels

22
Q

what happens to the contractile cells when the nodal cells reach depolarization (at +40mV)?
how?

A

positive cations moves from the nodal cells into the contractile cells through the Gap Junction

23
Q

define intercalated disks

A

Desmosomes+Gap Junction

btw nodal and contractile cells

24
Q

resting membrane potential of the contractile cells in the heart

A

around -85 mV / -90 mV

25
Q

threahold potential of the contractile cells in the heart

A

-70 mV

26
Q

upon entering of cations from the nodal cells and reaching the threshold, which channels are stimulated?

A

voltage gated Na+ channels open

27
Q

what happens after voltage gated Na+ channels open and Na+ ions get inside the contractile cell?

A
  • also L Type Ca++ are open (slowly)

- K+ ch open (K+ goes out -> repolerize the cell to 0 mV)

28
Q

what does the repolirization of the cell to 0mV causes?

A

L Type Ca++ are open faster and allows many Ca++ get inside the cell. in the same time K+ leave the cell

29
Q

what causes the platau in the contractile cell membrane potential?

A

L Type Ca++ are open -> many Ca++ get inside the cell. in the same time K+ leave the cell

30
Q

describe Ca++ induce Ca++ release mechanism

A

Ca++ is in the cells due to L -Type Ca++ channels -> Ca binds RYR-2 on the Sarcoplamic Reticulum -> RYR-2 opens its channel -> Ca leave the Sarcoplamis Reticulum to the cell

31
Q

describe the contraction mechanism itself of the contractile cells of the heart

A

Ca++ binds Troponin -> changes the shape of Tropomyosin -> Myosin head can now interact with the Actin
[over all Ca++ induces the cross-bridging]

32
Q

how does the contraction terminates?

A
  • L type Ca ch stop working
  • antipoter of H+/Ca++ using ATP to give back the Ca++ ions to the Sarcoplasmic Reticulum
  • Na/Ca antiporter on the Sarcoplasmic Reticulum
33
Q

what R can we find on the nodal cell of the heart?

A

B1 Adrenergic R (NE/N) -symp NS

M2-R (Ach) - para symp

34
Q

action of B1 Adrenergic R on the nodal cell

A

activates Gs GPCR -> cAMP increases -> pKA activates -> phoshorylation of L-Type Ca channels and other proteins -> Ca enters the cell BLA BLA BLA -> increased HR

35
Q

action of M2-R on the nodal cell

A

activates Gi GPCR -> B and Gamma subunits of Gi open K+ chennels -> K+ move out -> Hyperpolarization -> decreased HR
** A subunit -> cAMP decrease

SN Physiology Final (59 decks)

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