PBL

Question 1

Where does the posterior intercostal artery originate from?

Answer 1

Aorta

Question 2

Where does the anterior intercostal artery originate from?

Answer 2

Internal thoracic artery (or its branches)

Question 3

Where does the internal thoracic artery originate from?

Answer 3

The subclavian artery

Question 4

The internal thoracic artery bifurcates in to…

Answer 4

The musculophrenic and superior epigastric arteries

Question 5

List the three general sections of a vessel wall.

Answer 5

1. Tunica intima (innermost)
2. Tunica media
3. Tunica adventitia

Question 6

What is the general function of arteries?

Answer 6

To take oxygenated blood from the heart and deliver it to capillaries for oxygen and nutrient exchange to occur. (Exception is pulmonary artery which takes deoxygenated blood from right ventricle to lungs)

Question 7

List the four main types of artery in the body.

Answer 7

1. Large elastic (conducting arteries)
2. Medium muscular (distributing) arteries
3. Arterioles
4. Metarterioles

Question 8

What is the function of the large elastic/conducting arteries?

Answer 8

To ‘conduct’ blood from heart to regions of body where it can be distributed.

Question 9

List examples of large elastic/conducting arteries.

Answer 9

1. Aorta

2. Pulmonary arteries

Question 10

Describe the tunica intima of large elastic/conducting arteries.

Answer 10

Endothelial cells with a thin subendothelium of connective tissue and discontinuous elastic laminae.

Question 11

Describe the tunica media of large elastic/conducting arteries/

Answer 11

40-70 fenestrated elastic membranes with smooth muscle cells and collagen between these lamellae.

Question 12

Which layer is the thickest part of an elastic artery?

Answer 12

The tunica media

Question 13

Describe the tunica adventitia of large elastic/conducting arteries.

Answer 13

Thin layer of connective tissue containing lymphatics, nerves and vasa vasorum.

Question 14

What are vasa vasorum?

Answer 14

Blood vessels that supply blood to the artery

Question 15

What is the function of medium muscular/distributing arteries?

Answer 15

To distribute blood to the sub regions of the body

Question 16

Describe the tunica intima of medium arteries.

Answer 16

Endothelium, subendothelial layer, thick elastic lamina

Question 17

Describe the tunica media of medium arteries.

Answer 17

Approx 40 layers of smooth muscle connected by gap junctions to allow coordinated contraction

Question 18

Describe the tunica adventitia of medium arteries.

Answer 18

Minor Vasa vasorum, nerves, lymphatics

Question 19

What is the function of arterioles?

Answer 19

To carry blood from medium arteries to metarterioles.

Question 20

Describe the structure of arterioles.

Answer 20

1. Diameter of less than 0.1mm
2. Generally have 3 layers of smooth muscle cells
3. Internal elastic lamina is absent
4. External elastic lamina only present in larger arterioles

Question 21

What is the function of metarterioles?

Answer 21

To supply capillary beds with blood

Question 22

Describe the structure of metarterioles.

Answer 22

1. Intermediate rings of smooth muscle located at certain points (not continuous)
2. These rings are known as precapillary sphincters which contract to control blood flow to capillary bed.

Question 23

Describe the structure of a capillary.

Answer 23

1. Single layer of endothelium

2. Concordant basement membrane

Question 24

List the three types of capillary.

Answer 24

1. Continuous
2. Fenestrated
3. Sinusoidal

Question 25

What is the function of capillaries?

Answer 25

Nutrient, gas and waste exchange with tissues that they supply

Question 26

How do the three types of capillary differ from each other?

Answer 26

They each have variably sized gaps between the endothelial cells to allow for molecules structures leaving the capillary.

Question 27

Where would continuous capillaries be found?

Answer 27

Skeletal muscle where only water and ions can leave.

Question 28

Give an example of where sinusoidal capillaries would be located.

Answer 28

The liver as larger structures like cells and proteins need to be able to leave.

Question 29

Give an example of where fenestrated capillaries may be found.

Answer 29

Kidneys

Question 30

What is the function of the venous system?

Answer 30

To take deoxygenated blood from the capillaries and deliver it to the heart for oxygenation. (Exception is pulmonary vein which returns oxygenated blood from the lungs to the left atrium).

Question 31

List the types of vessels found in the venous system.

Answer 31

1. Postcapillary venules 2. Venules 3. Veins

Question 32

What is the function of postcapillary venules?

Answer 32

To receive blood from the capillaries and empty it in to venules.

Question 33

Why does tissue fluid tend to drain in to postcapillary venules?

Answer 33

Their pressure is lower than that of the capillaries or surrounding tissue.

Question 34

Describe the structure of postcapillary venules.

Answer 34

1. Endothelial lining with associated pericytes 2. Diameter of 10-30 micrometers 3. More pemeable than capillaries so site of WBC migration

Question 35

What is the function of venules?

Answer 35

To continue moving blood away from the capillaries.

Question 36

Describe the structure of venules.

Answer 36

1. Endothelium associated with pericytes or smooth muscle cells to form very thin wall. 2. Diameter up to 1mm 3. Valves to restrict back flow of blood

Question 37

Describe the structure of small and medium veins.

Answer 37

1. Well developed tunica adventitia | 2. Thin tunica intima and media

Question 38

Describe the structure of large veins.

Answer 38

1. Diameter greater than 10mm 2. Thicker tunica intima 3. Well developed longitudinal smooth muscle in tunica adventitia 4. Tunica media has circular smooth muscle 5. Valves to prevent back flow and help propel blood to heart

Question 39

What are venae comitantes?

Answer 39

Deep paired veins wrapped together with an artery in one sheath. The pulsations of the artery promote venous return.