Circulatory system

Question 1

Blood vessels

Metarterioles

Answer 1

1. short connecting vessel between true arteriole and capillaries, or direct to venules (shunt)
2. Can be a thoroughfare channel, direct shunt between capillaries and venules
3. encircled by precapillary sphincters

Question 2

Elastic Arteries

Answer 2

Largest in body

able to stretch without injury - smoothing of blood flow, contract and relax

Question 3

Capillaries

Answer 3

Primary exchange vessels, microscopic

highest numbers in tissue with high metabolic rate

10-100 per capillary bed

Question 4

Veins

Answer 4

Carry blood toward heart

collectors and reservoir vessels called capacitance vessels (65% blood supply)

venules join to form veins

Large lumen, thinner wall than arteries

valves

Question 5

vessel structure

Answer 5

1. Tunica externa - found in arteries and veins, tuica adventitia, outside layer
2. tunica media - found in arteries and veins
3. tunica intima - found in all blood vessels, is the only layer present in capillaries.

Question 6

What is the lining of the vessel

Answer 6

Endothelial cells

• Line the entire vascular tree
• provide smooth luminal surface: protect against intravascular coagulation
• intercellular clefts, cytoplasmic pores, and fenestrations allow exchange to occur between blood and tissue fluid
• capable of secreting a number of substances
• capable of reproduction

Question 7

Collagen fibers

Answer 7

Tunica Externa

1. Gives support
2. woven appearance
3. formed from protein molecules that aggregate into fibers
4. limited ability to stretch

Question 8

Vessel structure

Elastic fibers

Answer 8

1. composed of insoluble protein called elastin (smoothing action)
2. form highly elastic networks
3. play important role in passive tension to help regulate blood pressure throughout cardiac cycle

Question 9

smooth muscle fibers

Answer 9

1. Present in all segments of vascular system except capillaries
2. exert active tension in vessels when contracting

Question 10

Systemic circulation

Answer 10

1. Blood flows from the left ventricle of the heart through blood vessels to all parts of the body, except gas exchange tissues of lungs) and back to right atrium

Question 12

Pulmonary circulation

Answer 12

1. Deoxygenized venous blood flows pulmonary artery to lung arterioles and capillaries, where gases are exchanged. Oxygenated blood returns to the left atrium by pulmonary veins.

Question 13

Arterial Anastomoses

Answer 13

Arteries that open into other branches of the same or other arteries

Question 14

Arteriovenous anastomoses or Shunts

Answer 14

Occur when blood flows from an artery directly into a vein. (the metarteriole thoroughfare channel)

Question 15

Venous anastamoses

Answer 15

Abundant

Question 16

Anastomose

Answer 16

Collateral circulation

Makes sure blood gets where it needs to, if one line is blocked there’s another

Question 17

Systemic circulation Veins

Answer 17

1. The ultimate extensions of capillaries-unite into vessels of increasing size to form venules then veins
2. Venous blood from head neck, upper extremities and thoracic cavity (exept lungs) drains into the superior vena cava
3. Large veins of the cranial cavity are called dural sinuses

Question 18

Hepatic portal circulation

Answer 18

Veins from spleen, stomach, pancreas, gallbladder, and intestines, send blood to the liver by the hepatic portal vein

In the liver venous blood mingles with arterial blood in the capillaries and is eventually drained from the liver by hepatic veins that join the inferior vena cava