5- Vasculature 1

Question 1

Name 5 main types of blood vessels and where they carry blood

Answer 1

Arteries - from heart to tissues
Arterioles - arteries to capillaries
Capillaries - between arterioles and venules
Venules - capillaries to larger veins
Veins​ - from tissues to heart

Question 2

What is angiogenesis?

Answer 2

Angiogenesis is the growth of new blood vessels

Question 3

Three layers (tunics) in a blood vessel wall?

Answer 3

1- Tunica interna (intima) = innermost layer three sections:

• Epithelial layer, known as the endothelium
• Basement membrane
• Internal elastic lamina

2- Tunica media (middle layer; circular smooth muscle and elastic fibres)

3- Tunica externa (adventitia)
(outer layer; elastic and collagen fibres)

Question 4

What does an artery have that a vein does not?

Answer 4

internal and external elastic lamina

Question 5

What does a vein have that a vein does not?

Answer 5

Valves

Question 6

Two functional properties of blood vessels?

Answer 6

Elasticity and contractility

Question 7

The vascular smooth muscle of blood vessels is innervated by which nervous system?

Answer 7

sympathetic nervous system

Question 8

Two functions of elastic arteries?

Answer 8

1- Conducting arteries because they conduct blood from the heart to the medium-sized muscular arteries.
2- Pressure reservoir.

Question 9

Three characteristics of elastic arteries?

Answer 9

1- Largest arteries.
2- The tunica media has more elastic fibres and less smooth muscle than a muscular artery
3- It is able to receive blood under pressure and propel it onwards.

Question 10

Three characteristics of muscular arteries?

Answer 10

1- Medium-sized arteries.
2- The tunica media has more muscle than elastic fibres.
3- The walls are relatively thick (but no recoil ability).

Question 11

Two functions of muscular arteries?

Answer 11

1- Distributing arteries because they direct blood flow.

2- Capable of vasoconstriction and vasodilation to adjust the rate of flow.

Question 12

What are anastomoses?

Answer 12

Anastomoses are a union of two or more arteries supplying the same body region

Question 13

Name 3 examples of anastomoses

Answer 13

Circle of Willis underneath the brain
Coronary circulation of the heart
Gastrointestinal tract

Question 14

What do anastomoses do?

Answer 14

Create a secondary pathway so blood can continue to flow despite blockages

(They also occur between veins, arterioles and venules and work as safety net against blockages)

Question 15

What is collateral circulation?

Answer 15

Collateral circulation is the alternate route of blood flow through an anastomosis.

Question 16

3 characteristics of arterioles?

Answer 16

Very small, almost microscopic,
Tunica media: Thin, few layers of muscle.
Tunica interna: Thin, disappears distally.

Question 17

2 functions of arterioles?

Answer 17

Delivers blood to capillaries.

Resistance vessels: Regulates blood flow and arterial blood pressure through vasoconstriction and vasodilation.

Question 18

Where are metarterioles located?

Answer 18

at the terminal end of the arteriole

form branches into the capillary bed

Question 19

Where are precapillary sphincters located?

Answer 19

at the metarteriole-capillary junction

monitor blood flow via vasomotion; contraction and relaxation of sphincters

Question 20

4 characteristics of capillaries?

Answer 20

• The smallest blood vessels (microscopic).
• Tunica media and tunica externa are absent.
• Tunica interna: single layer of endothelial cells and a basement membrane.
• Found near every cell in the body but more extensive in highly active tissue (muscles, liver, kidneys and brain).

Question 21

Where are capillaries absent?

Answer 21

in epithelia, cornea and lens of eye and cartilage.

Question 22

3 functions of capillaries?

Answer 22

Connect arterioles to venules.
Form microcirculation.
Exchange of nutrients and wastes between blood and tissue fluid.

Question 23

3 types of capillaries?

Answer 23

Continuous capillaries

Fenestrated capillaries

Sinusoids

Question 24

Structure and location of continuous capillaries?

Answer 24

continuous tube; central nervous system, lungs, muscle tissue and skin

Question 25

Structure and location of fenestrated capillaries?

Answer 25

many holes in the plasma membranes of the endothelial cells; plasma membranes of the endothelial cells

Question 26

Structure and location of sinusoids?

Answer 26

The endothelial cells have unusually large fenestrations, the basement membrane is incomplete or absent, very large intercellular clefts (allow proteins and in some cases even blood cells to pass from the tissue into the bloodstream)

In liver, bone marrow, spleen, anterior pituitary, adrenal glands and parathyroid gland.

Question 27

2 types of venules?

Answer 27

post-capillary venules and muscular venules

Question 28

2 functions of venules?

Answer 28

They drain the capillary blood and begin the return flow of blood back toward the heart.
They serve as excellent reservoirs for accumulating large volumes of blood.

Question 29

Function of veins?

Answer 29

return blood to the heart

Question 30

Characteristics of veins

Answer 30

The tunica interna is thinner than in arteries and lacks the internal elastic lamina. It contains valves which are thin folds of the tunica interna, to prevent the backflow of blood.
The tunica media is also much thinner than in arteries and lacks the external elastic lamina (less elastic tissue and smooth muscle).
The tunica externa is thicker than in arteries.
significant flexibility

Question 31

What and where are vascular (venous) sinuses?

Answer 31

Vascular (venous) sinuses are veins with very thin walls with no smooth muscle to alter their diameters

in the brain’s superior sagittal sinus and the coronary sinus of the heart.

Question 32

3 functions of valves in veins?

Answer 32

prevent backflow
return of blood to the heart
adapt to blood volume changes

Question 33

systemic veins and venules contain what % of blood volume at rest?

Answer 33

64%

Question 34

Systemic arteries and arterioles contain what % of blood volume at rest?

Answer 34

13%

Question 35

what is capillary exchange?

Answer 35

the continuous movement of substances between the blood in systemic capillaries and interstitial fluid

Question 36

What are the three basic mechanisms of capillary exchange?

Answer 36

Diffusion
Transcytosis
Bulk flow

Question 37

3 locations for capillary diffusion?

Answer 37

Fenestrations or intercellular clefts
(water-soluble substances such as glucose and amino acids)

The lipid bilayer of endothelial cells
(lipid-soluble materials, such as O2, CO2, and steroid hormones)

Intercellular clefts of sinusoids
(larger, allow even proteins and blood cells to pass through)

Question 38

The BBB is formed by what?

Answer 38

non-fenestrated epithelium with tight junctions in the brain capillaries

Question 39

What can pass through the BBB?

Answer 39

A few water-soluble substances, such as glucose (active transport).
Creatinine, urea, and most ions (slow movement).
Lipid-soluble substances, such as oxygen, carbon dioxide, alcohol, and most anaesthetic agents through the endothelial plasma membrane.

Question 40

Bulk flow is comprised of what?

Answer 40

filtration and reabsorption;

faster rate of movement than during diffusion or osmosis. It regulates relative volumes of blood and interstitial fluid

Question 41

Filtration is…

Answer 41

Filtration is the movement of material into the interstitial fluid
( promoted by blood hydrostatic pressure and interstitial fluid osmotic pressure)

Question 42

Reabsorption is…

Answer 42

Reabsorption is the movement from the interstitial fluid into capillaries
(promoted by blood colloid osmotic pressure.)

Question 43

Net filtration pressure is….

Answer 43

the balance of the pressures that promote filtration and reabsorption
(Whether fluids leave or enter capillaries)

Question 44

What is blood hydrostatic pressure?

Answer 44

Pressure that promotes filtration

Question 45

What is blood colloid osmotic pressure?

Answer 45

Pressure that promotes reabsorption