Cardiac Physiology

Question 1

What is cardiac output at rest?

Answer 1

5 L/min

CO=SV x HR

Question 2

What are the two divisions of circulation?

Answer 2

• systemic

- pulmonary

Question 3

What is the normal stroke volume of the heart?

Answer 3

60mL per beat

Question 4

What controls regional flow of blood?

Answer 4

Arteriole resistance, local regulation

Question 5

What is the equation for blood flow?

Answer 5

Flow = Change in pressure/Resistance
Flow = (P1-P2)/R

Question 6

What is laminar flow pattern?

Answer 6

• Blood flow against wall of vessel has very low velocity

- Blood in middle of vessel has maximum velocity

Question 7

Where in the arterioles and veins are cellular constituents of blood carried ?

Answer 7

-The middle of the vessel

Question 8

How is turbulent flow different from laminar flow?

Answer 8

• not physiological
• Makes noise
• Happens when you have obstruction in vessel or a narrowing of the vessel
• damages endothelium

Question 9

What is a murmer?

Answer 9

-Turbulent flow in the heart

Question 10

What is bruit?

Answer 10

-turbulent flow in the arteries

Question 11

What determines resistance to fluid flow in a tube (blood vessel or airway)?

Answer 11

• Length
• Fluid Viscosity
• Radius of tube (only one that really changes)

Question 12

What is systole?

Answer 12

-The stage in the cardiac cycle in which the ventricles are ejecting blood into the aorta/pulmonary artery

Question 13

What is diastole?

Answer 13

• Stage in cardiac cycle when R and L ventricles are filling with blood for the next contraction
• Pressure in arterial system is lowest

Question 14

What is the pulse pressure?

Answer 14

-The difference between systolic and diastolic pressure

Question 15

What is the equation for mean arterial pressure?

Answer 15

MAP = diastolic pressure + 1/3 Systolic pressure

Question 16

What is contractility?

Answer 16

The intrinsic property of the cardiac muscle that accounts for varying force of contraction, it is the net effect of many variables

Question 17

What keeps the majority of the capillary beds closed?

Answer 17

Sympathetic Tone

Question 18

What are fenestrae?

Answer 18

-Holes in capillaries that allow water, ions, glucose, and amino acids through

Question 19

What is head pressure?

Answer 19

pressure in the arterioles going into the capillary bed

Question 20

What is back pressure?

Answer 20

Pressure in the venule leaving capillary beds

Question 21

What are the three types of control in the vascular system?

Answer 21

• Nervous control - SYMPATHETIC ONLY
• Hormone control
• Local control

Question 22

What are the factors that determine fluid movement through across capillary walls? (starling forces)

Answer 22

• Water permeability (hydraulic conductance)
• Capillary hydraulic pressure
• Capillary osmotic pressure (Albumin)
• Interstitial fluid pressure
• Interstitial osmotic pressure

Question 23

What generates capillary osmotic pressure?

Answer 23

-albumin (negatively charged)

Question 24

What are the three divisions of local control of blood flow?

Answer 24

1. autoregulation
2. active hyperemia
3. reactive hyperemia

Question 25

Autoregulation

Answer 25

flow held constant in response to fluctuating arterial pressure

Question 26

active hyperemia

Answer 26

flow increases to match metabolic activity in real time

Question 27

reactive hyperemia

Answer 27

flow increases to replenish tissue metabolic requirements after the fact

Question 28

What does angiotensin II do?

Answer 28

• vasoconstriction to increase total peripheral resistance
• Increase aldosterone to increase Na reabsorption
• increases thirst
• increases Na-H exchange

Question 29

What depolarizes the membrane potential of the SA node to reach threshold for the L-type Ca channels?

Answer 29

• Funny current through the HCN channel

- T-type Ca channels (voltage gated)

Question 30

What activates the HCN channel?

Answer 30

• Hyperpolarization

- Increased levels of cAMP

Question 31

What ion generates the current though gap junctions?

Answer 31

Potassium

Question 32

What is inotropy?

Answer 32

contractility

Question 33

What alters contractility?

Answer 33

factors that influence Ca flux

Question 34

Does varying preload alter contractility?

Answer 34

No

Question 35

What is ESPVR a measure of?

Answer 35

Contractility

Question 36

What are 3 substances that result in local vasodilation?

Answer 36

• Histamine
• Bradykinin
• Prostaglandin-E

Question 37

What are 3 local vasoconstrictors?

Answer 37

• Serotonin
• Thromboxane A2
• Prostaglandin-F

Question 38

What initiates the RAAS system?

Answer 38

-decreased perfusion of the kidneys