Blood Vessels

Question 1

What are the components of blood vessels ?

Answer 1

• endothelium
• smooth muscle
• connective tissue

Question 2

Describe the structure of endothelium

Answer 2

• thin and flat cells
• link together by cell junctions to form tubes

Question 3

Explain the function of endothelium

Answer 3

• line the entire cardiovascular system
• keep blood in the system
• allow transfer between the vessels and the surroundings

Question 4

What are the 2 circulatory systems ?

Answer 4

• pulmonary system (right side)
• systemic system (left side)

Question 5

What is the overall strategy of blood vessels ?

Answer 5

Heart > elastic artery > muscular artery > arteriole > capillary > venule > vein (and back to the heart)

Question 6

What is the function of the elastic arteries ?

Answer 6

• smooth blood flow
• at high pressure so the wall can stretch and the volume of the vessel can increase

Question 7

What is the function of the muscular artery ?

Answer 7

Note - also known as distributing artery
- controls and distributes blood flow to different parts of the body

Question 8

What is the function of arterioles ?

Answer 8

Pressure control to the capillaries

Question 9

What is the function of the capillaries ?

Answer 9

• have very thin walls so majority of exchange takes place here

Question 10

What is the function of the venules ?

Answer 10

• gathers blood from the capillaries
• fluid exchange between plasma and tissue fluid

Question 11

What is the function of the veins ?

Answer 11

Return of the blood to the heart

Question 12

What is the general structure of the blood vessels ?
(Except capillaries and sinusoids)

Answer 12

• they have 3 layers :
  1) tunica intima
  2) tunica media
  3) tunica adventitia

Question 13

What are the boundaries of the tunica media ?

Answer 13

• internal boundary is the internal elastic lamina
• external boundary is the external elastic lamina

Question 14

Describe the structure of the tunica intima

Answer 14

• made of endothelium and little amounts of connective tissue
• innermost layer

Question 15

Describe the structure of the tunica media

Answer 15

• made up of smooth muscle and connective tissue
• makes up the majority of the vessel

Question 16

Describe the structure of the tunica adventitia

Answer 16

• made up of connective tissue
• outermost later
• holds the vessel together

Question 17

Describe the orientation of smooth muscle in the blood vessels

Answer 17

• has a circular arrangement
• controls diameter of the vessel

Question 18

Give some examples of elastic arteries

Answer 18

• aorta
• pulmonary artery

Question 19

Describe blood supply to large arteries

Answer 19

• the walls of large arteries are too thick to receive adequate nutrient supply and waste disposal from the centre of the vessel
• so these vessels have blood vessels within their walls
• this is known as vasa vasora

Question 20

What are terminal arterioles ?

Answer 20

• control blood flow to capillary beds
• the pressure within them is enough to get blood through but not too much to burst the capillaries

Question 21

What are the 3 types of endothelium ?

Answer 21

• continuous
• fenestrated
• discontinuous

Question 22

Describe the structure and function of continuous endothelium

Answer 22

• no gaps
• complete basement membrane
• line nearly all blood vessels and capillaries
• allow the exchange of solutes and gases

Question 23

Describe the structure and function of fenestrated endothelium

Answer 23

• there are pores between the endothelial cells
• complete basement membrane
• found in the capillaries of endocrine glands
• allow the exchange of larger molecules such as hormones

Question 24

Describe the structure and function of discontinuous endothelium

Answer 24

• there are gaps between the endothelial cells
• incomplete basement membrane
• found in sinusoids which occur in the bone marrow
• allow the exchange of whole cells

Question 25

What are sinusoids ?

Answer 25

Big capillaries with very thin walls

Question 26

Describe the structure of veins

Answer 26

- small tunica media and large tunica adventitia - contain valves

Question 27

Describe the structure and function of valves

Answer 27

- they are folds of the tunica intima - they ensure one way flow of blood

Question 28

Why do arteries and veins run together ?

Answer 28

- the blood flowing through the artery causes it to pulse - the pulse causes the vein to be massaged and this allows blood to flow through the vein and back into the heart

Question 29

What is the importance of muscle contraction in relation to veins ?

Answer 29

Muscle contraction squeezes veins and moves blood along