CHAPTER 21--Muscle Blood Flow and CO During Exercise & Coronary Circulation and Ischemic Heart Disease

Question 1

When exercise begins, the shift (___________) in blood flow to the skeletal muscles is needed to bring O2 and nutrients to the muscles and carry CO2 and waste products away.

Answer 1

vasodilation

Question 2

Blood flow to the exercising muscles can increase

___-_____ fold depending on the intensity of exercise and the aerobic capacity of the individual.

Answer 2

25-50

Question 3

Local Control of Muscle Blood Flow During Exercise X 3

1. ↓O2 content in the tissue fluid because it is used rapidly during exercise—causes _______ of arteriole walls which signals the release of vasodilator substances.
2. ____________ is one of the vasodilator
   substances but it cannot stimulate enough
   blood flow.
3. Other vasodilator substances—K+, LA, ↑CO2

Answer 3

dilation

Adenosine

Question 4

Sympathetic and Hormonal Regulation During Exercise

Along with the local _______ substances, the
sympathetic nervous system and hormones also have a role in increasing blood flow to the exercising muscles.

Releases noreponephrine ( receptors) which 
\_\_\_\_\_\_\_\_\_\_\_ blood vessels in non-exercising areas so reduces blood flow to the kidneys and gut by 1/3 to ½ of resting values.

Adrenal medulla releases norepinepherine and
epinepherine which works as a __________ on ß receptors
in skeletal muscle.

Answer 4

vasodilator

vasoconstricts

vasodilator

Question 5

Total Body Circulatory Readjustments During Exercise

1. Mass Sympathetic Discharge—at the onset of exercise, voluntary signals to the brain cause:

(1) muscle contractions,
(2) the Vasomotor Center (VMC) initiates the sympathetic discharge to the whole body,
(3) inhibition of parasympathetic signals to the heart.

Answer 5

a. Heart is stimulated to increase HR and force of contraction.

b. Most of the arterioles in the body are strongly contracted except for those involved in exercise. Redistribution of blood from nonmuscular
areas to the skeletal muscles. (Cardiac and cerebral blood vessels have limited capacity to vasoconstrict so maintain blood flow during exercise).

c. The walls of the veins contract which increases VR.

Question 6

Total Body Circulatory Readjustments During Exercise

2. INCREASE in Mean Arterial Pressure results from __________of metarterioles and small arteries in nonworking areas and an increase in mean systemic filling pressure caused by the contraction of the veins.

• Mean arterial pressure increases 20-80 mmHg during exercise.
• The increase in ______ _______ is dependent on exercise intensity. Jogging or swimming may only raise it 20 mmHg but high intensity exercise like a maximal bench press may raise it 80 mmHg or more.

• This increase in MAP will also cause a stretch in the walls of the blood vessels thus assisting with signaling vasodilation. This stretch on the walls to cause vasodilation is one of the most important factors for
increasing ____ ________ to the working muscles.

Answer 6

vasoconstriction

arterial pressure

blood flow

Question 7

Total Body Circulatory Readjustments During Exercise

3. INCREASE in Cardiac Output—the increase in CO is in proportion to the ___ demand of exercise.

• Increased CO provides ___ and nutrients to the
working muscles and this is just as (if not more)
important than the need to increase HR and
force of contraction.

• An untrained individual can increase CO by 4
fold while a trained endurance athlete can
increase CO 7 fold and an elite athlete 9 fold or
more.

Answer 7

O2

O2

Question 8

Coronary Circulation and Ischemic Heart Disease

___ of all deaths in industrialized (primarily, Western) countries are due to heart disease (as compared to 22% due to cancers).

_____ of all deaths result from coronary artery disease (CAD).

Almost all elderly people have some level of CAD.

Answer 8

45%

33%

Question 9

Risk factors for CAD

NAME 3 THAT ARE IRREVERSIBLE:

Answer 9

1. Aging
2. Male
3. Genetic predisposition

Question 10

Risk factors for CAD

NAME 6 THAT ARE REVERSIBLE:

Answer 10

1. Cigarette smoking— doubles risk of MI
2. Hypertension
3. High LDLs from high saturated fat diet
4. Physical Inactivity
5. Obesity
6. Diabetes if from lack of exercise and obesity

Question 11

Anatomy of Coronary Blood Supply X 4

1. ____ _________Artery supplies the rt. ventricle
   and posterior of left ventricle.
2. _____ ________ Artery supplies the anterior and
   lateral portions of the left ventricle
3. Venous flow from Lt. ventricle returns to
   the Rt. Atrium via the ________ _______
4. Venous flow from Rt. ventricle enters the
   ______ __________ via small anterior cardiac
   veins.

Answer 11

Rt. Coronary

Lt. Coronary

coronary sinus.

right atrium

Question 12

Coronary blood flow in the _____ ventricle muscle decreases during SYSTOLE because of the strong
compression of the ventricle around the intramuscular blood vessels (opposite of other tissues)

During DIASTOLE, the cardiac muscle
________ so blood flow rapidly increases.

Answer 12

left

relaxes

Question 13

Coronary blood flow at rest is about 225 ml/min which equals about 5% of total CO at rest. During strenuous exercise, coronary blood flow can increase___ TO ___ fold.

Answer 13

3 to 4

Question 14

Control of Coronary Blood Flow X3

1. Local Muscle Metabolism—arteriole________ occurs in response to increased nutrient needs of cardiac muscle.

*** This is similar to control of local blood flow of
other tissues.

Answer 14

vasodilation

Question 15

Control of Coronary Blood Flow X 3

2. O2 Demand—the heart’s need for O2 is a major regulator of coronary blood flow. Normally, _____% of the O2 is removed as the blood flows through the coronary blood vessels. Therefore, blood flow must ______ in proportion to O2 demand.

When ATP degrades to ADP, AMP and then adenosine,
adenosine is a major __________ substance.

Other _________ in the heart are K+, H+, CO2 and
nitric oxide.

Answer 15

70%

increase

vasodilator

vasodilators

Question 16

Control of Coronary Blood Flow X 3

3. Nervous Control—nervous stimulation comes
   from the autonomic nervous system:

a. _______________ –release of acetylcholine from vagus nerves slows heart rate and decreases force of contraction.
b. ____________—norepinephrine and epinephrine cause the blood vessels to vasoconstrict and increase HR and force of contraction.

__________ cells have ALPHA receptors = vasoconstrict

________ arterioles have ß receptors = vasodilate.

More influence from vasoconstrictors—people with ischemia have chest pain (angina) during times of significant vasoconstriction.

Answer 16

Parasympathetic

Sympathetic

Epicardial

intramuscular

Question 17

Energy Supply for Heart

• 70% from __________ metabolism

• Glycolysis (glucose) must be used under
anaerobic or ________ conditions to produce
ATP.

• __________ glycolysis uses lots of glucose and forms lots of lactic acid which may contribute to the angina in ischemic conditions.

Answer 17

lipid (fat)

ischemic

Anaerobic

Question 18

Ischemic Heart Disease

Definition—_________ coronary blood flow

____________—the most frequent cause of diminished blood flow in the coronary arteries.

Answer 18

insufficient

Atherosclerosis

Question 19

Ischemic Heart Disease

Causes : NAME 5 CAUSES

Answer 19

1. .Genetic predisposition
2. .Hypertension—damages walls of blood vessels
3. .Sedentary lifestyle
4. .Obesity
5. .High cholesterol

Question 20

Ischemic Heart Disease

Cholesterol deposits collect beneath the ________of the damaged blood vessel walls. These deposits are invaded by _________ tissue and become _______ forming plaque. The plaque protrudes into the lumen of the blood vessel and either partially or completely blocks blood flow. The most common place for this to form is first few cm of the coronary arteries.

Answer 20

endothelium

fibrous

calcified

Question 21

Acute Coronary _______—most frequently occurs in people with underlying atherosclerosis.

Answer 21

Occlusion

Question 22

If the plaque breaks through the _______, it comes in direct contact with the flowing blood. Since the plaque has an ________ surface, platelets adhere to it, fibrin is deposited and ______ get trapped forming a blood clot. This blood clot is called a ___________.

Answer 22

endothelium

unsmooth

RBCs

thrombus

Question 23

If the blood clot breaks away and travels via the blood to a smaller branch of the artery, it causes a coronary ______ in the more distal part of the blood vessel.

Answer 23

embolus

Question 24

Collateral Circulation—in the heart, the smaller coronary arteries have ___________

• When an occlusion occurs in a large coronary artery, the anastomoses begin to __________ immediately.
• Initially, the blood flow through these ______vessels is not enough to keep the cardiac muscle it must supply alive.

Answer 24

anastomoses.

dilate

smaller

Question 25

**Over time (within a month), blood vessels widen and blood flow _________ so that coronary circulation is
about back to normal.

**This is why people with atherosclerosis don’t know it until the plaque build up is excessive and the ________circulation is not enough. Heart’s ability to pump is
severely compromised.

Answer 25

increases

collateral

Question 26

Myocardial Infarction (MI)—immediately after an acute coronary occlusion, blood does not flow beyond the occluded area except for the small amount of collateral 
circulation. The area of the heart that receives little or no blood supply is said to be \_\_\_\_\_\_\_\_\_

Answer 26

infarcted.

Question 27

Soon after the occlusion, collateral circulation_________but the blood flow to this area becomes stagnant. The cardiac muscle uses all the O2 so the _____________ hemoglobin caused the infarcted area to take on a bluish-brown color.

Answer 27

increases

deoxygenated

Question 28

Stages of Recovery from MI x 3

1. If the area of ischemia is small, there is little to no cell death. Even the nonfunctional area will come back as collateral circulation __________.
2. If area of ischemia is large, some of the muscle cells on the interior will die rapidly (within 1 to 3 hours). The nonfunctional area will either survive or die depending on how fast _________ circulation can get to it within 3 weeks.
3. Ischemia can stimulate _________ activity so dead tissue is replaced with fibrous tissue (scar tissue).

Answer 28

increases

collateral

fibroblast

Question 29

Function of Heart After Recovery from an MI:

1. The most important factor in treating a patient after an MI is complete body rest during the recovery process.
2. The heart has the potential to recover to full functional capacity. However, most often the heart’s pumping capabilities are compromised _____ that of a healthy heart.
3. Even with a compromised heart, under resting conditions, the heart can pump enough blood to make most day-to-day activities comfortable.
4. The normal heart is capable of pumping _____-____ % above resting (called _____ ______). Even with a 100% cardiac reserve, the person can perform most daily activities.

Answer 29

below

300-400%

cardiac reserve

Question 30

Drug Treatments x 2

1– ________ drugs such as nitroglycerin and other nitrates

2– Beta Blockers such as propranolol (block sympathetic
receptors)

Surgical Treatments

1– ________ –balloon-tipped catheter
2– _______—stainless steel mesh
3– Laser beam from tip of catheter—dissolves the ______
4– By-Pass Surgery using a ____________ vein from leg as a graft

Answer 30

Vasodilator

Angioplasty

Stents

plaque

subcutaneous

Question 31

Four Causes of Death After Acute Coronary Occlusion:

1. Decreased Cardiac Output—if the cardiac muscle fibers cannot contract normally, then cardiac output decreases.

a. _____ _______ occurs when the dead or nonfunctional area develops pressure from the inside of the ventricle therefore, the pumping capacity of the left ventricle is
diminished.

Answer 31

Systolic Stretch

Question 32

Four Causes of Death After Acute Coronary Occlusion:

2. Damming of Blood in the Venous System—if the heart isn’t pumping blood forward, it is damming in the atria, pulmonary vessels and the
   veins.

a. Not noticeable initially after MI but within a few days, this decreased ___ means less blood flow to the kidneys so urine production is diminished as well. This leads to increased blood volume.

b. This leads to______ and which produces
congestive heart failure.

Answer 32

CO

edema

Question 33

Four Causes of Death After Acute Coronary Occlusion:

3. Ventricular Fibrillation—usually after a large infarct but can also occur after a small occlusion.

a• Two dangerous periods after an MI when V-fib is most likely to occur:
– Within the first 10 minutes of the MI
– Another beginning an hour or so later and lasting a few hours

b• Acute ______ in blood flow to the cardiac muscle causes a rapid decrease of K+ which increase K+ in the extracellular fluids. This increase in extracellular K+ causes ________.

c• Ischemia prevents the cardiac muscle cells from completely repolarizing so the exterior of the heart remains more _________ compared to the interior so not being in sync creates abnormal impulses that cause fibrillation.

d• Powerful _________ reflexes occur after an MI causing irritability of the heart which leads to fibrillation.

Answer 33

decrease

fibrillation

negative

sympathetic

Question 34

Four Causes of Death After Acute Coronary Occlusion:

4. Rupture of the Infarcted Area—does not occur within
   the first few days after an MI.

a. A few days after the MI, the cardiac muscle begins to
_________ and the dead muscle bulges outward with
each contraction.

b. This systolic stretch becomes _______ until the heart
ruptures.

c. When the heart ruptures, the loss of blood flow into
the _________ space causes cardiac tamponade by
blood collecting in the pericardial cavity.

d. Because of the compression on the heart, blood cannot
flow into the ________ atrium and the individual dies
suddenly because there is no CO.

Answer 34

degenerate

greater

pericardial

right