Cardiovascular Physiology 1 (9/17b) [Biomedical Sciences 1] Flashcards Preview

Unit 1 > Cardiovascular Physiology 1 (9/17b) [Biomedical Sciences 1] > Flashcards

Flashcards in Cardiovascular Physiology 1 (9/17b) [Biomedical Sciences 1] Deck (48)
Loading flashcards...
1
Q

Path of RBC from vena cava to vena cava

A
Vena cava
Right atrium
-Tricuspid Valve
Right Ventricle
-Pulmonary Valve
Pulmonary Circulation
-Pulmonary artery → vein
Left atrium
-Mitral/Bicuspid Valve
Left Ventricle
-Aortic Valve
Systemic circulation
-Aorta → Vena Cava
2
Q

Atrioventricular valves

A

tricuspid and mitral valves

3
Q

Semilunar valves

A

aortic and pulmonary valves

4
Q

When do arteries carry deoxygenated blood?

A

Pulmonary artery carries deoxygenated blood to the lungs to get oxygenated

5
Q

Main functions of cardiovascular system

A

Deliver enough blood to satisfy metabolic needs

Deliver O2 and nutrients, remove waste

Redistribute cardiac output

6
Q

Range of metabolic demand

A

measure respiration/oxygen consumption rate to understand metabolic demand

Resting = about 250 mL O2/min

Exercise = about 5000 mL O2/min

7
Q

Cardiac Output (CO)

A

measure cardiac output (L/min) by Heart Rate (beats/min) x Stroke Volume (mL/beat)

CO = HR * SV

8
Q

Cardiac output increases as heart rate does, but not enough to keep up with oxygen consumption. What is needed?

A

redistribution of blood

9
Q

During heavy exercise, more of cardiac output will be directed to ___ ___ ___

A

active skeletal muscle

10
Q

___-____ fold increase in blood flow to active muscle

A

20-30

11
Q

Sodium-Potassium (Na+/K+) pump

A

sets up electrochemical gradients

Lots of K+ inside cell, little outside → pumped out

Lots of Na+ outside cell, little inside → pumped in

Creates an electrical potential of about -90 mV in a resting cardiac/muscle cell

An electric current is needed to depolarize the current → action potential

12
Q

Na+/K+ pump creates an electrical potential of about ___ mV in a resting cardiac/muscle cell

A

-90 mV

13
Q

Action Potential - Skeletal Muscle (Myocytes)

A

Threshold reached → Na+ channels open quickly and Na+ rushes in (upstroke)

Depolarizes the cell, brings it up a little past neutral

Na+ channels close → K+ channels open and K+ rushes out (downstroke)

All of this happens in about 1-2 milliseconds

14
Q

Action Potential - Cardiac Muscle (Nodal Cells)

A

Slow calcium (Ca2+) channels open and calcium comes in while potassium is leaving → they oppose each other and makes it a slow process → creates a plateau

Calcium has positive charge, so it keeps depolarizing the membrane; but potassium leaving hyperpolarizes it

Once Ca2+ channels close → membrane potential brought back to -90 mV

Upstroke rapid influx of Na+, plateau is balanced influx of Ca2+ and efflux of K+, downstroke is efflux of K+

happens in about 300 milliseconds

15
Q

Contraction Ability - Skeletal vs Cardiac Muscle

A

Skeletal muscle → needs innervation to cause contraction, some electrical stimulation needed

Cardiac muscle → could beat on its own without innervation, has sinus or AV nodal cells

16
Q

Automaticity

A

Nodal cells have an unstable resting potential → creates automaticity (able to beat on its own)

Gradual inward current of Na+ creates funny current

Once threshold is reached → action potential spreads to other myocytes

17
Q

Flow of Signal Conduction

A

Sinoatrial (SA) node (60-100 bpm)

Atrioventricular (AV) node (40-60 bpm)

Bundle of His (15-40 bpm)

Bundle branches

Purkinje fibers

18
Q

Overdrive suppression

A

high intrinsic rate of SA node makes it the dominant pacemaker

Ectopic foci can become pacemakers in pathological states

19
Q

AV node delay allows time for…

A

atrial contraction and ventricular filling

aka leads to coordinated heart beat

20
Q

How do we evaluate the signal of the heart?

A

with an ECG

21
Q

Normal sinus rhythm is defined by

A

Regular rhythm

rate between 60-100 bpm

normal shape of waveform (shape of P, QRS, T waves) (duration of PR, ST, and QT intervals)

22
Q

What do P, QRS, and T segments of ECG correspond to in the heart?

A

P = atrial depolarization

QRS complex = ventricular depolarization (also partly atrial repolarization) (mitral valve closing)

T wave = ventricular repolarization

23
Q

What parts of ECG correspond to ventricular systole and diastole?

A

Ventricular Systole → beginning QRS complex to end of T wave

Ventricular Diastole → end of T wave to beginning of next QRS complex

24
Q

ECG abnormalities

A

Sinus tachycardia → fast rhythm

Sinus bradycardia → slow rhythm

Triplet Premature Ventricular Contraction → ectopic foci, wide bizarre signals

Ventricular fibrillation → wavy line with no distinct rhythm/shapes

Atrial fibrillation → lacks P wave

25
Q

The signal that makes the heart beat

A

the depolarization of cardiac myocytes

26
Q

How does the signal produce a heart beat?

A

Excitation-Contraction Coupling (E-C Coupling)

27
Q

E-C Coupling - Contraction/Systole

A

Ca2+ influx during action potential triggers release of Ca2+ from sarcoplasmic reticulum (SR)
(Calcium-induced calcium release)

Ca2+ binds to troponin, causing it to shift, allowing myosin-actin interaction and contraction

28
Q

E-C Coupling - Relaxation/Diastole

A

Ca2+ falls as it is transported

  • Into SR via SERCA pump (requires ATP)
  • Out of cell by membrane Ca2+ pump and Na+/Ca2+ exchanger

Fall in Ca2+ causes troponin to shift back, blocking actin-myosin interaction and contraction

29
Q

Echocardiography

A

uses sound waves to image the heart and evaluate the beat

provides info about stroke volume and ejection fraction

30
Q

Stroke Volume (SV)

A

the volume of blood ejected each beat

SV = End Diastolic Volume (EDV) - End Systolic Volume (ESV)

31
Q

Ejection Fraction (EF)

A

the fraction of end diastolic volume ejected each beat

normal is about 50-70%

EF = SV/EDV

32
Q

Issues with heart response

A

Valve disease (stenosis and regurgitation)

Decreased contractility during systole → systolic dysfunction

Decreased relaxation during diastole → diastolic dysfunction

33
Q

Valve Disease - Stenosis

A

narrowing of valve opening

34
Q

Valve Disease - Regurgitation

A

valve allows backflow of blood

35
Q

Phases of Cardiac Cycle

A

Ventricular Systole (contraction)

  • Isovolumetric contraction
  • Ejection of blood into aorta

Ventricular Diastole (relaxation)

  • Isovolumetric relaxation
  • Passive filling of ventricle
  • Active filling of ventricle → atrial systole (“atrial kick”)
36
Q

How can the autonomic nervous system charge heart rate?

A

The sympathetic and parasympathetic systems change the slope of the resting membrane potential by changing Na+/K+ levels, impacting the funny current

37
Q

Cardiac Regulation - Sympathetic

A

Positive Chronotropic effect → increases slope

Norepinephrine acts on beta-1 receptors in SA node to increase HR

38
Q

Cardiac Regulation - Parasympathetic

A

Negative Chronotropic effect → decreases slope

Acetylcholine released from vagus nerve acts on muscarinic receptors to decrease HR

39
Q

As HR increases (above ~150 bpm), diastole duration decreases, reduces time for ___ ___

A

ventricular filling

40
Q

To increase cardiac output, increased HR is accompanied by increased ventricular filling, but how?

A

Venoconstriction by sympathetic nervous system

Muscle pump - muscles in our legs contract, squeeze veins, push blood back up to heart

41
Q

Factors that affect stroke volume

A

Preload (increases)
Afterload (decreases)
Contractility (increases)

42
Q

Preload

A

volume of blood in ventricles at the end of diastole

Directly correlated with SV → increased preload = increased SV

Increased preload → increased stretch on myocyte → stronger contraction → increased stroke volume

Length-tension relationship (Frank-Starling Curve)

Venous return and duration of diastole affect preload

43
Q

Afterload

A

resistance the ventricle must overcome to eject blood

The left ventricle must overcome aortic pressure

Inversely correlated with SV → increased afterload = decreased SV

Hypertension and aortic stenosis increase afterload, hypotension decreases afterload

44
Q

Contractility

A

strength of myocardial contraction, calcium dependent

Directly related with SV → increased contractility = increased SV

Inotropy (+/-)affects calcium concentration in myocyte

45
Q

Positive (+) Inotropy

A

Positive inotropy → increased calcium concentration → stronger contraction → increased stroke volume

SNS → norepinephrine acts on β-1 receptors to increase calcium concentration

Cardiac glycosides (digitalis) also increases calcium concentration

46
Q

Negative (-) Inotropy

A

Negative inotropy → decreased calcium concentration → weaker contraction → decreased stroke volume

Calcium channel blockers (diltiazem) decrease calcium concentration

47
Q

At the beginning of ___ ___, mitral (on left) and tricuspid (on right) valves close

A

isovolumetric contraction

48
Q

At the beginning of ___ ___, the aortic valve closes when ventricular pressure falls below aortic pressure

A

isovolumetric relaxation