Blood Vessels & Flow

Question 1

What is the general order of blood flow through the circulatory system?

Answer 1

Heart → Arteries → Arterioles → Capillaries → Venules → Veins → Heart

Question 2

What are the three layers (tunics) of blood vessels?

Answer 2

Tunica intima, Tunica media, Tunica externa

Question 3

What is the function of the tunica intima?

Answer 3

Provides a smooth lining to reduce friction and allow selective transport

Question 4

What is the function of the tunica media?

Answer 4

Contains smooth muscle and elastic fibers; responsible for vasoconstriction and vasodilation

Question 5

What is the function of the tunica externa?

Answer 5

Provides support and protection through connective tissue

Question 6

What is a lumen in a blood vessel?

Answer 6

The hollow interior of a blood vessel through which blood flows

Question 7

What is an elastic artery?

Answer 7

A large artery close to the heart with abundant elastic fibers that expand and recoil to maintain pressure gradient

Question 8

What is a muscular artery?

Answer 8

A medium-sized artery with thick smooth muscle that distributes blood to specific organs

Coronary arteries & Carotid arteries

Question 9

What is an arteriole?

Answer 9

A small resistance artery that regulates blood pressure and controls blood flow into capillaries

Question 10

What is a capillary?

Answer 10

The smallest blood vessel where gas, nutrient, and waste exchange occurs

Question 11

What is perfusion?

Answer 11

The delivery of blood into the capillaries of tissues

Question 12

What is microcirculation?

Answer 12

Flow of blood through arterioles, capillaries, and venules

Question 13

What are the three types of capillaries?

Answer 13

Continuous, Fenestrated, Sinusoid

Question 14

Where are continuous capillaries found?

Answer 14

Muscles, skin, CNS (blood-brain barrier)

Question 15

What are fenestrated capillaries?

Answer 15

Capillaries with pores that allow passage of larger solutes, found in kidneys and endocrine glands

Question 16

What are sinusoid capillaries?

Answer 16

Capillaries with large gaps for passage of plasma proteins and cells, found in liver and bone marrow

Question 17

What is an intercellular cleft?

Answer 17

Small gap between endothelial cells in capillaries for solute movement

Question 18

What are fenestrations?

Answer 18

Pores in capillary walls allowing rapid exchange of substances

Question 19

What is a metarteriole?

Answer 19

A vessel between arteriole and capillary with both arteriole and capillary characteristics

Question 20

What is a precapillary sphincter?

Answer 20

A ring of smooth muscle controlling blood flow into a capillary

Question 21

What is a capillary bed?

Answer 21

A network of 10–100 capillaries fed by a single arteriole

Question 22

What is a thoroughfare channel?

Answer 22

A channel allowing blood to bypass the capillary bed and flow to venule

Question 23

What is a vascular shunt?

Answer 23

A metarteriole + thoroughfare channel combination bypassing capillaries

Question 24

What is an arteriovenous anastomosis?

Answer 24

A vessel directly connecting an arteriole to a venule

Question 25

What is vasomotion?

Answer 25

Rhythmic contraction/relaxation of precapillary sphincters regulating blood flow

Question 26

What is a vein?

Answer 26

A vessel that returns blood to the heart with thin walls, valves, and large lumens • Most veins carry deoxygenated blood. • Pulmonary veins are the exception — they carry oxygenated blood.

Question 27

Why do veins have valves?

Answer 27

To prevent the backflow of blood due to low pressure and gravity

Question 28

What is a venule?

Answer 28

Venules: • Are the smallest veins. • Receive blood from capillaries. • Allow WBCs (white blood cells) to exit (emigrate) through their thin walls into surrounding tissues to respond to infection or injury — a process called diapedesis or emigration.

Question 29

What are venous sinuses?

Answer 29

Wide, thin-walled veins with no smooth muscle, reliant on surrounding tissue

Question 30

What are anastomotic veins?

Answer 30

Veins connecting superficial and deep venous systems

Question 31

What is diffusion?

Answer 31

The passive movement of solutes from high to low concentration across membranes

Question 32

What is reabsorption?

Answer 32

Movement of water from interstitial fluid into the blood

Question 33

What is filtration?

Answer 33

Movement of water from blood into interstitial fluid

Question 34

What is transcytosis?

Answer 34

Movement of large molecules across capillary endothelial cells using vesicles

Question 35

What is active transport?

Answer 35

ATP-powered transport of molecules against their concentration gradient

Question 36

What is capillary hydrostatic pressure (CHP)?

Answer 36

The pressure of blood pushing fluid out of capillaries

Question 37

What is interstitial fluid hydrostatic pressure (IFHP)?

Answer 37

Pressure in tissues pushing fluid into capillaries

Question 38

What is blood colloid osmotic pressure (BCOP)?

Answer 38

Osmotic pressure due to plasma proteins pulling water into capillaries

Question 39

What is interstitial fluid colloid osmotic pressure (IFCOP)?

Answer 39

Very low osmotic pressure pulling fluid out of capillaries

Question 40

What is net filtration pressure (NFP)?

Answer 40

The difference between CHP and BCOP; determines direction of fluid flow

Question 41

At the arterial end of a capillary, is filtration or reabsorption dominant?

Answer 41

Filtration (CHP > BCOP)

Question 42

At the venous end of a capillary, is filtration or reabsorption dominant?

Answer 42

Reabsorption (BCOP > CHP)

Question 43

What are trans-membrane proteins?

Answer 43

Integral membrane proteins that span the cell membrane and transport substances

Question 44

What is a concentration gradient?

Answer 44

A difference in solute concentration across a space or membrane

Question 45

What is endocytosis?

Answer 45

Process of taking substances into a cell using vesicles

Question 46

What is exocytosis?

Answer 46

Process of releasing substances from a cell via vesicles