Blood vessels and circulation

Question 1

What are the three types of blood vessels?

Answer 1

• Arteries (carry blood away from the heart and toward capillaries)
• Capillaries (carry blood from the arterioles to the venules)
• Veins (carry blood toward the heart and away from veins)

Question 2

Describe the structure of arteries.

Answer 2

• Tunica intima - inner layer of epithelial cells
• Tunica media - smooth muscle with some elastic tissue; thick layer in arteries; important in blood pressure regulation
• Tunica externa - thin layer of fibrous elastic connective tissue

Question 3

Describe the structure of veins.

Answer 3

• Tunica intima - inner layer; valves prevent retrograde movement of blood
• Tunica media - smooth muscle; thin in veins
• Tunica externa - heavy layer of fibrous connective tissue

Question 4

Describe the structure of capillaries.

Answer 4

Microscopic vessels with only one layer - tunica intima; blood flow in capillaries regulated by smooth muscle in arterioles

Question 5

Describe the function of arteries.

Answer 5

Distribution of nutrients, gases, etc., with movement of blood under high pressure; assist in maintaining the arterial blood pressure and thus maintain blood flow.

Question 6

Describe the function of veins.

Answer 6

Collect blood for return to the heart; low pressure vessels.

Question 7

Describe the function of capillaries.

Answer 7

• Serve as exchange vessels for nutrients, wastes, and fluids.
• Osmosis and filtration are major forces that drive capillary exchange.
• outwardly directed forces are greater at arterial end of capillary, moving from blood to tissue
• inwardly directed forces are greater at venous end of capillary, moving fluid from tissue to blood
• excess tissue fluid not returned to blood is collected by lymphatic system

Question 8

What does blood circulation refer to?

Answer 8

The flow of blood through all the vessels, which are arranged forming a complete circuit or circular pattern.

Question 9

What is systemic circulation and its path?

Answer 9

Carries blood throughout the body; path goes from left ventricle through aorta, smaller arteries, arterioles, capillaries, venules, venae cavae, to right atrium.

Question 10

What is pulmonary circulation and its path?

Answer 10

Carries blood to and from the lungs; arteries deliver deoxygenated blood to the lungs for gas exchange; path goes from right ventricle, through the pulmonary arteries, lungs, pulmonary veins, to left atrium

Question 11

What is hepatic portal circulation?

Answer 11

• Unique blood route through the liver
• Vein (hepatic portal vein) exists between two capillary beds
• Assists with homeostasis of blood glucose levels

Question 12

What is fetal circulation?

Answer 12

• Refers to circulation before birth
• Modifications required for fetus to efficiently secure oxygen and nutrients from the maternal blood
• unique structures include the placenta, umbilical arteries and veins, ductus venosus, ductus arteriosus, and foramen ovale

Question 13

What is blood pressure?

Answer 13

Push, or force, of blood in the blood vessels; highest in arteries, lowest in veins.

Question 14

What is the blood pressure gradient?

Answer 14

Causes blood to circulate - liquids can flow only from the area where pressure is higher to where it is lower.

Question 15

What is hypertension (HTN)?

Answer 15

High blood pressure.
Can cause vessels to rupture; can increase workload of heart, causing abnormal thickening of myocardium.

Question 16

Name five factors that influence blood pressure.

Answer 16

1) Blood volume - the larger the volume, the more pressure is exerted on vessel walls; diuretics can be used to promote water loss and thus loss of total blood volume
2) Strength of heart contractions - affect cardiac output; stronger heartbeat increases pressure; decreased rate decreases pressure
3) Heart rate - increased rate increases pressure; decreased rate decreases pressure
4) Blood viscosity (thickness) - less-than-normal viscosity decreases pressure, more-than-normal viscosity increases pressure
5) Peripheral Resistance (PR) - resistance to blood flow, affected by many factors, including the vasomotor mechanism (vessel muscle contraction/relaxation)

Question 17

What is polycythemia?

Answer 17

Abnormally high hematocrit, which increases blood viscosity and this increases blood pressure.

Question 18

What is considered a normal systemic arterial blood pressure?

Answer 18

Although blood pressure varies within normal range; normal is considered 120/80 at rest.

Question 19

Venous return of blood to the heart depends on these five mechanisms.

Answer 19

1) Strongly beating heart
2) Adequate arterial blood pressure
3) valves in the veins
4) pumping action of skeletal muscles as they contract
5) changing pressures in the chest cavity caused by breathing

Question 20

What is a ‘pulse’?

Answer 20

Alternate expansion and recoil of the blood vessel wall.

Question 21

Name the nine major “pulse points” named after the arteries over which they are felt.

Answer 21

1) superficial temporal artery
2) facial artery
3) Carotid artery
4) Axillary artery
5) Brachial artery
6) Radial artery
7) Femoral artery
8) Popliteal artery
9) Dorsalis pedis artery