physio - E2: CV

"right" vs "left" side circulation

right = pulmonary (deoxygenation)
left = systemic (oxygenated)

flow is proportional to pressure & inversely proportional to resistance

ohm's law

↑ resistance = ____ CO

↓

↑ flow = ____ pressure

↑

↑ length = ____ resistance

↑

↓ radius = ____ resistance

↑

what impacts flow the most

radius!

compliance

distensibility of a structure
(pressure will stay the same if more blood enters)

exitation-contraction coupling

1. pacemaker cells = AP along T tubules
2. voltage-gated ion channels = Ca2+ INTO cell
3. SR releases Ca2+
4.Ca2+-induced Ca2+-released
5. Ca2+ to troponin C...

6. Ca2+-ATPase = put Ca2+ back into SR
Ca2+/Na exchanger = Ca2+ OUT of cell

Conduction pathway of the heart

SA node, AV node, bundle of His, L/R bundle branches, and Purkinje fibers

ventricular muscle AP (phases)

Phase 0 = Na+ - depol
Phase 1 = K+ leaves - partial repol
Phase 2 = Ca2+ comes in same time K+ leaves - plateau
Phase 3 = K+ leaves - repol

(Phase 4 = rest)

SA node will fire spontaneously during which phase?

Phase 4

EKG wave meanings

P = atrial depol (contraction)
QRS = ventricular depol (contraction)
T = ventricular repol (relaxation)

normal rate of SA node. What slows it down?

100 bpm
- pns tone = 70 bpm

what happens if SA node fails?

AV node 40-60 bpm
- if fails = bundle of his = 20-40 bpm

AV node must have a long ______ = protect against arrhythmias

absolute refractory period
(beta blockers extend this period if used)

atrial fibrillation rate

350-600 bpm (thats why we need AV node to relax HR)

PNS vs SNS chronotropic (beats per min) effect
- what do they release?

PNS = negative chronotropic effect
- Ach -> muscarinic

SNS = positive chronotropic effect
- E/NE -> adrenergic (a,beta)

what drug is used for bradycardia?

atropine = blocks muscarinic receptors (↓ pns)

inotropy vs dromotropy vs chronotropy

inotropy = force of contraction
dromotropy = conductance
chronotropy = bpm

leads:
- frontal plane
- transverse plane

frontal = 6 limb leads
transverse = 6 precordial leads

ventricular diastole
atrial systole
isovolumic ventricular contraction
ventricular ejection
isovolumic relaxation

ventricular diastole = AV valves open

atrial systole = atrial kick

isovolumic vent contraction = aortic valve open, AV valves closed

ventricular ejection = ventri p > aortic p (120mmHg)

isovolumic relaxation = ventri p < aortic p, aortic valve closes, AV valves open

dicrotic notch

vibration (backflow) caused by closure of aortic valve = change in aortic pressure

A, C, V wave in left atira

A = atrial systole
C = mitral valve closes in vent cont
V = atrial filling in vent diastole

stroke volume equation

SV = EDV - ESV

ejection fraction equation

EF = SV/EDV

ejection fraction is usually ___ %

55-65%

S1

lub" = AV valves close

S2
- s2 split

"dub" = semilunar valves close
- inspiration = S2 split (↓ pressure = ↑ SV), delays P2 (pulomonic valve)

S3

"Tennessee" = blood hitting stiff ventricle

S4

"kentucky" = atrial kick

CO equation

Q = HR x SV

2 forms of congestive heart failure:
Preserved EF vs Reduced EF

preserved = diastolic dysf
reduced = systolic dysf

Cardiac Index equation

CI = Q/BSA (body surface area)
- only used in icu

Frank-Starling Law
- give relationships
- why does this occur

↑ stretch = ↑ EDV = ↑ contraction = ↑SV

there is increased sensitivity of troponin C to Ca2+!

____ is the MOST important determinant of SV

EDV!!!

Preload vs. afterload

Preload = EDV created by venous return

Afterload = systemic/aortic pressure

5 factors that increase preload

1. ↑ circulating blood
2. skeletal muscle contr
3. inspiration (increase abdominal pressure -> blood to heart)
4. atrial systole
5. venoconstriction

SV is determined by what 3 things?

preload, afterload, contractility

↑ preload = ____ SV

↑

2 factors that increase afterload

1. low compliance of ventricle
2. stenosis

use BP to test vascular resistance

↑ afterload = ____ SV

↓

left vs right-shift in Frank-Starling

left = ↑ contractility
right = ↓ contractility

↑ compliance = ____ SV

↑

LV failure = ___ compliance = ___ pressure = ___ EDV = ___ SV = ___ HR

↓ compliance = ↑ pressure = ↓ EDV = ↓ SV = ↑ HR

site of greatest vascular resistance ??

arteries & arterioles

they control BP the most!

benefit of capillaries

large surface area = exchange of nutrients

benefits of venules/veins

high capacitance (can hold a LOT of blood), low pressure

↑ venous tone (aka venoconstriction) = _____ venous return

increase

↑ SVR = ___ afterload = ____ SV

↑ afterload = ↓ sv

what 2 things affect ESV

1. afterload
2. contractility

!!!

what effects EDV

preload !!!

Pulse pressure equation

PP = SBP-DBP

MAP equations

MAP = DBP + 1/3 (PP)

MAP = CO x SV

what 4 things det SBP

1. MAP is proportional to CO & SVR
2. Increases in SV = increase SBP & PP
3. low aortic compliance = high SBP (atherosclerosis)
4. DBP

↑ CO & ↑ SVR = ___ MAP

↑

↑ SV = ___ SBP = ___ PP

↑ SBP = ↑ PP

↓ compliance = _____ SBP

↑

what 3 things det DBP

1. vascular resistance
2. runoff from aorta
3. time

↑ vascular resistance = ___ DBP

↑

↑ runoff = ___ DPB

↑

↑ HR = ____ DBP

↑ (less time for drop in pressure)

SVR is what

systemic vascular resistance (aka total peripheral resistance!!)

How is SVR determined?

vasoconstriction
vasodialation

vasoconstriction = ____ SVR = ___ afterload = ____ SV

↑ SVR = ↑ afterload = ↓ SV

vasoconstriction = ____ VR

↓

vasodilation = ____ SVR = ___ afterload = ____ SV

↓ SVR = ↓ afterload = ↑ SV

vasodilation = ___ VR

↑

Central venous pressure (CVP) is pressure of blood in the _____

right atria !!!

(& vena cavas)

what do you do when CO is LESS THAN 5???

add saline!!!

ON EXAM

↓ CVP = ___ venous return

↑

↑ CVP = _____ venous return = ____ EDV = ___ preload = ___ SV

↓venous return = ↓ EDV = ↓ preload = ↓ SV

3 ways venous return can be altered

1. supine -> standing
2. skeletal muscle contr
3. ventilation

supine to standing = ____ VR = ___ CO = ___BP

↓ all

walking = ____ VR = ____ CO = ___ BP

↑ all

inspiration = ____ VR = ____ CO

↑ both

transmural pressure

pressure able to distend or dilate a structure

CO must equal

VR (venous return)!!

issues with filling vs contraction

filling = diastolic problem
contraction = systolic problem

HR is ONLY determined by?

PNS -
SNS +

main response system that protects against systemic arterial BP

baroreceptors!

primary site of cardiovascular control

medulla oblongata

PNS (vagal) fibers innervate...

SA, AV, conduction pathways, cardiac myocytes

PNS fibers main effects

lower HR, conduction, & contraction

SNS have which receprots

beta & alpha

SNS receptors:
B1
A1
B2

B1 = ↑ HR, conduction, contractility
A1 = vasoconstriction/venoconstriction
B2 = vasodilation

net effect of SNS is ___ & ___!!

vasoconstriction & ↑SVR

NE vs E affinity for SNS receptors

NE - alpha
E - B2

baroreceptors: primary vs secondary

primary = carotid sinus (glossopharyngeal CN IX)
secondary = aortic arch (vagus CN X)

carotid message = _____ stretch = activates ____ nervous system = ____ tachy

↑ stretch = activates PARASYMPATHETIC nervous system = ↓ tachy

veno vs vasoconstriction

veno - ↑blood flow
vaso - ↓blood flow

see if a change BP/HR is due to a change of position causing fainting - a good baroreceptor reflex test!

tilt-table test

need constant blood flow

brain & kidney (unlike GI)

when is blood flow highest in the myocardium?

diastole!!!

which is why tachy is an ISSUE (less diastole)

how do you increase O2 supply?

increase coronary BF

what drug provides vasodilation

nitroglycerin = has nitric oxide

myogenic autoregulation

brain will have constant supply of O2

want MAP to be ____

>65mmHg!!!

How is renal & GI affected during exercise?

vasoconstriction



(SNS - don't want to pee/eat while running)

SNS - when cold vs hot

cold = vasoconstriction
hot = vasodilation