Circulation 2

Question 1

Do Arteries have a low or high resistance? Why?

Answer 1

Low resistance
Elastin and Smooth muscle cushions systole

Question 2

Which blood vessel has the highest resistance? What does this equal?

Answer 2

Arterioles
Total Arteriolar resistance= Total Peripheral resistance

Question 3

What determines the radius of a blood vessel? What happens to resistance, flow and BP when blood vessels constrict?

Answer 3

Smooth Muscle
Constriction= Decreased radius
Increased resistance
Decreased flow
Increased Blood pressure

Question 4

What determines rate of flow in capillaries? (2)

Answer 4

Arteriolar resistance and Pre-capillary sphincter

Question 5

Describe the area and flow in capillaries

Answer 5

Large area and slow flow

Question 6

Do veins have a low or high resistance? What is the pressure in veins?

Answer 6

Very low resistance
~10mmHg

Question 7

What 3 factors aids the Veins in returning blood to the heart?

Answer 7

Skeletal muscle
Valves (prevent Backflow)
Respiratory pump

Question 8

What type of Innervation do blood vessels lack?

Answer 8

Parasympathetic

Question 9

Name three Circulating hormonal Vasoconstrictors

Answer 9

Epinephrine
Angiotensin II
Vasopressin

Question 10

Name two circluating Hormonal Vasodilators

Answer 10

Epinephrine
ANP

Question 11

Name two Local Humoral vasoconstrictor.

Answer 11

Endothelin 1
Internal Blood pressure autoregulation

Question 12

Where and how is Endothelin-1 produced? What 5 factors stimulate it?

Answer 12

Big Endothelin 1 converted to Endothelin 1 by Endothelin by Endothelin converting enzyme in endothelium
Factors stimulating:
-Vasopressin
-Angiotensin II
-Cytokines
-Thrombin
-Oxidative reactive species

Question 13

What does Endothelin-1 act upon? What does this result in?

Answer 13

G coupled proteins stimulating IP3 to release Ca2+ to contract smooth muscle

Question 14

What eight humoral factors result in Vasodilation?

Answer 14

-Hypoxia
-Prostacyclin
-Adenosine
-Nitric oxide
- CO2
-K+
-H+
-Tissue breakdown products

Question 15

Where and How is Nitric oxide produced?

Answer 15

Endothelium
Ach and Insulin stimulate Ca2+ release
L-arginine (Amino acid)–> Nitric oxide via NO synthase

Question 16

What are three blood volume regulators?

Answer 16

RAAS
ADH
Adrenal and kidneys

Question 17

What is blood pressure autoregualtion?

Answer 17

Smooth muscle is stretched when BP increases
Results in it contracting

Question 18

What two locations are Peripheral Chemoreceptors and arterial Baroreceptors located in? (both found here)

Answer 18

Carotid sinus
Aortic arch

Question 19

What is the afferent and efferent nerve for baroreceptors respectively? Where does it travel to?

Answer 19

Glossopharyngeal (CNIX)
and Vagus (X)
Medulla

Question 20

What type of regulation do Arterial baroreceptors provide? What happens if there is a continuous increase in BP?

Answer 20

Short term (Min-Min)
Baseline for arterial baroreceptors will change to that BP

Question 21

What is the other type of baroreceptor (not arterial) called? where are they found (2)?

Answer 21

Cardiopulmonary baroreceptors
Atria and ventricles

Question 22

What do cardiopulmonary baroreceptors result in the secretion of?

Answer 22

Atrial Natriuretic peptide (ANP)

Question 23

Where are central chemoreceptors found? What are they most sensitive to? What does this result in?

Answer 23

Medulla
High PaCO2
Vasoconstriction

Question 24

What affects Blood pressure in the long term? What influences this?(4)

Answer 24

Volume of blood
Na+, H2o, RAAS and ADH

Question 25

What are Peripheral chemoreceptors most sensitive to (2)? What does this factor cause to happen?

Answer 25

PO2 and pH
Decreased parasympathetic to heart increased pulse and increased CO