Ch. 12 - Circulatory & Cardiac Physiology

Question 1

What is the Perfusion Pressure?

Answer 1

Pressure at the arterial end minus pressure at venous end

Question 2

What has the most powerful relationship with resistance?

Answer 2

Radius - if radius increases by 2, the resistance drop 16X

Question 3

What are the names of the vessels blood flows through, in consistent order?

Answer 3

• Artery
• Arteriole (controller)
• Capillary
• Venule
• Vein

Question 4

What has the largest cross-sectional area and the lowest blood flow velocity?

Answer 4

Capillaries

Question 5

What is Laplace’s Law?

Answer 5

Wall stress = Pr/t

Question 6

What arteries carry deoxygenated blood? And what veins carry oxygenated blood?

Answer 6

• Pulmonary and Umbilical arteries
• Pulmonary veins

Question 7

What vessels account for the greatest total area and largest surface area?

Answer 7

Capillaries

Question 8

What vessels account for the largest drop in BP?

Answer 8

Arterioles

Question 9

Where is most of the blood volume held within the systemic venous circulation?

Answer 9

Systemic veins - 60%

Question 10

What is Cardiac Output equal to?

Answer 10

Heart Rate x Stroke Volume

Question 11

What is the limits for Bradycardia and Tachycardia?

Answer 11

Bradycardia <60 bpm

Tachycardia >100 bpm

Question 12

In the Frank-Starling Mechanism, what is the most important determinant of CO?

Answer 12

Venous Return

Question 13

What does imbalance between myocardial oxygen supply and demand cause?

Answer 13

Ischemia (angina) and myocardial infarction (MI)

Question 14

What is preload and afterload?

Answer 14

• Preload - filling of the ventricles (EDV)
• Afterload - Force against which the heart contracts

Question 15

What is the best way to increase cardiac output?

Answer 15

Increase preload (increase venous return)

Question 16

What will happen to CO at very high heart rates?

Answer 16

CO will actually fall, diastolic filling wont be able to keep up, so even though HR is up, the SV will fall

Question 17

What is the first sound of S1 “lub”?

Answer 17

Sound of the AV valves (mitral and tricuspid) closing, this sound begins systole (ventricular contraction)

Question 18

What is the second sound S2 “dub”?

Answer 18

Sound of the semilunar valves (aortic and pulmonic) closing, this sound begins diastole (ventricle filling)

Question 19

What are the AV valves and the semi-lunar valves?

Answer 19

• AV - mitral & tricuspid
• Semi-lunar - aortic & pulmonic

Question 20

What can a heart murmur be in a diastolic vs systolic?

Answer 20

• Diastolic
  
  • Aortic insufficiency, mitral stenosis
• Systolic
  
  • Aortic stenonis, mitral regurgitation

Question 21

What is the route of electrical signals in the heart?

Answer 21

• SA node
• AV node
• ventricular bundles (His/Purkinje)
• ventricular myocytes
• ventricular contraction

Question 22

Where is the SA node located?

Answer 22

In posterior wall of Right Atrium, near opening of SVC

Question 23

Where is the AV node located?

Answer 23

In the lower right interatrial septum

Question 24

What are the nerves that have sympathetic and parasympathetic control over the heart?

Answer 24

• Sympathetic - T1-T4 (sympathetic chain)
• Parasympathetic - Vagus nerve (CN X)

Question 25

What part of the vagus nerve innervates the SA and AV nodes?

Answer 25

• SA - right vagus nerve
• AV - left vagus nerve

Question 26

What is the Bainbridge Reflex?

Answer 26

Stretch of the atria due to increased blood volume, increases HR and CO = Pumps more blood out of pulmonary system to prevent pulmonary edema.

Question 27

What are baroreceptors activated by and what do they cause?

Answer 27

Activated by high BP

Cause - lower HR, vasodilation, lower BP

Question 28

Where are the receptors to sense pressure?

Answer 28

• Carotid sinus - CN IX
• Aortic arch baroreceptors - CN X