Block 3 - Bsf: Coronary Flow

Front 1

Which organ has the highest amount of blood flow?

Back 1

Kidneys (followed by the heart)

Front 2

Which organ has the least amount of blood flow?

Back 2

Skeletal muscle (followed by the skin)

Front 3

Approximately how much of the total CO goes to GI tract, kidneys, skeletal muscle, heart and brain?

Back 3

80%

Front 4

T/F

Distribution of CO greatly depends on environment (T⁰, humidity, etc) and physical activity.

Back 4

True!

Front 5

Basal flow refers to what conditions?

Back 5

When person is in fasted, resting state, and at normal t⁰ (room) and humidity.

Front 6

What does the difference between basal flow and maximal flow represent?

Back 6

The flow capacity or vasodilator reserve for the organ.

Front 7

Which organs have a relatively large vasodilator reserve?

Back 7

Most organs! Skeletal muscle, GI tract, skin

Front 8

What organ is an example of an organ with a relatively small vasodilator reserve?

Back 8

Kidneys

Front 9

The major coronary vessels (epicardial vessels) serve as ______________ vessels.

Back 9

Low-resistance distribution

Front 10

The smaller branches of the major coronary vessels go into the a)____________and become b)_______________ vessels that regulate coronary blood flow.

Back 10

a) Myocardium
b) Microvascular resistance

Front 11

In the capillary network of the coronary arteries, each a)__________ is closely associated with several capillaries. There are (short/long) diffusion distances (O2, CO2, metabolites).

Back 11

a) Myocyte
b) Short

Front 12

What is the principle factor responsible for perfusion of the myocardium?

Back 12

Aortic pressure

Front 13

What are the regulatory factors of coronary blood flow?

Back 13

Physical factors: aortic pressure and cardiac work

Neural control: cardiac sympathetic nerves

Metabolic factors

Front 14

What are the most important regulatory factors of coronary blood flow?

Back 14

Metabolic factors

Front 15

T/F

Coronary blood flow is phasic.

Back 15

True!

Front 16

Coronary blood flow is reduced during (systole/diastole).

Why?

Back 16

Systole

Beause contraction of the myocardium creates extravascular pressure that decreases flow.

Front 17

Which region of the heart is most susceptible to ischemic injury?

Back 17

The subendocardial region is most susceptible to ischemic injury, because during systole, contraction that creates extravascular pressure occurs to a greater extent within the subendocardium.

Front 18

Most coronary blood flow occurs during (systole/diastole).

Why?

Back 18

Diastole

Because of relaxation of the myocardium. As the ventricle begins to relax in early diastole, the compressive forces are removed and blood flow is permitted.

Front 19

a) When does coronary blood flow reach a peak?

b) Then, it falls passively as what falls towards its diastolic value?

Back 19

a) Early diastole

b) Aortic pressure

Front 20

What is the direct vascular effect of cardiac sympathetic nerves?

Back 20

Only transient vasoconstriction (via alpha1-AR) followed by vasodilation.

Front 21

What is the indirect vascular effect of cardiac sympathetic nerves?

Back 21

Increase heart work (metabolism, via alpha1-AR) followed by the production of local vasodilator metabolites.

Front 22

What is the direct vascular effect of cholinergic stimulation (Ach "spillover" from the vagus)?

Back 22

Vasodilation of the coronary artery (Ach effect, endothelium-dependent mechanism)

Front 23

What is the indirect vascular effect of cholinergic stimulation (Ach "spillover" from the vagus)?

Back 23

Decrease heart work (↓metabolic activity) and causes a decrease in coronary blood flow.

Front 24

T/F

Locally produced metabolites produce the greatest effect on coronary blood flow.

Back 24

True!

Front 25

Which metabolites dilate the arterioles thereby adjusting O2 supply to demands?

Back 25

Adenosine
NO
Decreased intracellular ATP level

Front 26

How does decreased intracellular ATP lead to vasodilation in coronry arteries?

Back 26

low ATP→ opening of the K+ATP channels → hyperpolarization of the smooth muscle → vasodilation

Front 27

The balance between myocardial metabolic rate and myocardial O2 supply is called:

Back 27

Myocardial oxygen balance

Front 28

Myocardial O2 supply refers to the amount of what?

Back 28

O2 delivered to myocardium in the arterial blood.

Front 29

Myocardial O2 supply depends on what 2 things?

Back 29

Coronary blood flow and arterial O2 content

Front 30

Compare/contrast tylenol and aspirin

Back 30

Both analgesic and antipyretic.
Only aspirin is anti-inflammatory and effective anti-platelet.
Acetomenaphen has mainly CNS inhibitory effects (ex: temperature control in hypothalamus and pain).

Front 31

What determines myocardial metabolic rate?

Back 31

Myocardial O2 demands:

Amount and the type of activity of the myocardium as well as cardiac output (stroke volume and heart rate).

Front 32

T/F

In a healthy heart O2 demand (metabolic rate) exceeds O2 supply (delivery).

Back 32

False!

In a healthy heart O2 demand (metabolic rate) matches O2 supply (delivery).

Front 33

What is MO2C?

Back 33

Myocardial O2 consumption (myocardial metabolic rate)

Front 34

How is MO2C affected by ↑heart rate, ↑ionotropy, ↑afterload, and ↑preload?

Back 34

MO2C is increased. It is affected by all factors that would have an effect on cardiac output.

Front 35

How can MO2C be estimate by Fick's principle (what's the equation)?

Back 35

MO2C = coronary blood flow x (AO2-VO2)

Front 36

What is MO2C at rest, during heavy exercise, and during cardiac arrest?

Back 36

At rest: 8 mlO2/min per 100g
Heavy exercise: 70 mlO2/min per 100g
Cardiac arrest: 2 mlO2/min per 100g

Front 37

Why is cardiac O2 supply flow-limited?

Back 37

Because nearly all O2 is extracted from myocardial capillaries

Front 38

What occurs in myocardial ischemia?

a) Inhibition of ____________.
b) Intracellular (acidosis/alkalosis).
c) These lead to accumulation of what ion?
d) This enhances Na/Ca exchange and results in _______ accumulation in the cytosol.
e) Overload of (d) causes what to happen?

Back 38

a) Na, K-ATPase
b) Acidosis
c) Na+
d) Ca2+
e) Interferes with myocardial contraction and can lead to cell death.

d)

Front 39

What can "buffer" (to some extent) excess Ca2+ in the cell?

However, once there is overload, what happens? (what opens, what happens to the membrane potential, and what loses function?)

Back 39

Mitochondrial uptake

Once the mito experiences overload, this opens the mitochondrial permeability transition pore. This will dissipate the membrane potential of the mito and result in loss of function of the F1F0 ATPase.

Front 40

Ca-dependent proteases (calpains) may be activated when?

What does this lead to?

Back 40

During Ca overload

Cell death