Kim. Special Circulation

Question 1

The difference between basal flow and maximal flow for a specific organ is called the

Answer 1

Flow capacity or vasodilator reserve

Question 2

Blood flow w/in coronary arteries _____ during cardiac systole and _______ during diastole

Answer 2

Decreases

Increases

Question 3

Most of the blood flow to the myocardium occurs during ________

Answer 3

Diastole

Question 4

Coronary blood flow is primarily regulated by ?

Answer 4

Changes in tissue metabolism

Question 5

Unlike most other vascular bed, activation of sympathetic nerves to the heart causes

Answer 5

Transient vasoconstriction followed by vasodilation

Question 6

When a person exercises, the increased CO primarily goes to the active skeletal muscles, heart and skin. Blood flow decreases to the __________

Answer 6

Gastrointestinal and renal circulation

Question 7

Normally, coronary arteries dilate with increased heart rate and metabolism, if the coronaries are diseased and their vasodilator reserve is limited, increases in HR can _____

Answer 7

Limit coronary flow, lead to myocardial ischemia, and anginal pain

Question 8

The ______ of coronary flow overrides the direct coronary nervous effects w/in seconds.

Answer 8

Metabolic control

This explains the transient vasoconstriction from sympathetics that is followed by vasodilation

Question 9

What does ICP do to cerebral blood flow?

Answer 9

Collapses veins

Decrease effective CPP

Reduces blood flow

Question 10

Cerebral blood flow is highly related to metabolism of the tissue. _______ is the main factor regulating cerebral blood flow

Answer 10

Arterial PCO2

Question 11

Substances that increase the acidity of the brain tissue will __________ cerebral blood flow

Answer 11

Increase

Question 12

As long as arterial PO2 is normal, cerebral blood flow is regulated by PCO2. However, a _________ in arterial PO2 will cause and increase in cerebral blood flow

Answer 12

Large decrease in arterial PO2

Question 13

Neuropeptides originating in the brain;

Vasoactive intestinal polypeptide
Calcitonin gene-related peptide
Substance P

Cause

Answer 13

Vasodilation

Question 14

Neuropeptide Y, a brain neuropeptide, causes

Answer 14

Vasoconstriction

Question 15

Activation of sympathetic nerves that innervate the larger cerebral vessels has relatively little influence on cerebral blood flow because of?

Answer 15

The strong autoregulation mechanism in the brain

Question 16

When skeletal muscle is not contracting, little oxygen is required and only about _____ of the capillaries are perfused

Answer 16

One-forth

In contraction, and active hyperemia, all anatomical capillaries may be perfused

Question 17

W/ rhythmic or phasic contractions, mean blood flow increases _________

Answer 17

During the contractions

If measured w/o avg the blood flow is phasic, but averaged, it is increasing during

Question 18

Why does blood flow decrease during contraction and increase during relaxation of muscle?

Answer 18

Because the muscles mechanically compress the vessels

Question 19

A sustained muscle contraction does what to blood flow ?

Answer 19

Decreases the blood flow during the duration of the contraction, but increases the blood flow after due to a reflexive hyperemia

Question 20

Decreased oxygen in muscle greatly _ ____ blood flow ?

Answer 20

Enhances

Question 21

During activity, the blood flow in muscles increases. Why ?

Answer 21

1. Decreased O2 causes increase
2. Vasodilator substances are released during contraction: adenosine, potassium
   Increased lactic acid, CO2 and H ions.

Question 22

Under resting conditions, a significant portion of the vascular tone is generated by _________ therefore, in resting skeletal muscle, nervous control is dominant

Answer 22

Sympathetic activity

Question 23

Splanchnic circulation includes blood flow to the _ _ _ _

Answer 23

GI tract
Spleen
Liver
Pancreas

Question 24

All splanchnic ciruclation blood is supplied by which three arteries?

Answer 24

Celiac

Superior mesenteric

Inferior mesenteric

Question 25

All blood that courses through the gut, spleen, and pancreas flow immediately into the?

Answer 25

Liver, via the portal vein

Question 26

Hepatic blood flow is derived from which two source?

Answer 26

The hepatic artery

The portal vein

(About 3/4 use by liver is derived from hepatic arterial blood)

Question 27

During active absorption of nutrients, blood flow in the villi and adjacent regions of the submucosa and the muscle layers of the intestinal walls is

Answer 27

Increased

Question 28

Possible causes of increased blood flow during GI activity?

Answer 28

Several vasodilator substances released from mucosa during digestion (cholecystokinin, vasoactive intestinal peptide, gastrin, secretin)

GI glands release bradykinin

Decrease O2 conc in gut wall

Question 29

What does sympathetic stimulation do to GI tract?

Answer 29

Causes intense vasoconstriction of the arterioles w/ greatly decreased blood flow

(Symp = fight or flight
Parasymp = rest and digest)

Question 30

_______ causes a decrease in volume in the large-vol intestinal and mesenteric veins. Displacing large amounts of blood to other parts of the circulation that actively need them.

Answer 30

Sympathetic stimulation

Splanchnic circulation functions as a venous reservoir