5 Structure and function of blood vessels

Question 1

All blood vessel must be….

Answer 1

resilient and flexible so they can stay open during movement

Question 2

What is the structure of all vessels but capillaries?

Answer 2

• Lumen
• Tunica interna
• Tunica media
• Tunica adventitia

Question 3

Structure of tunica interna

Answer 3

• basal lamina (epithelia)
• squamous epithelial layer
• sub-epithelial connective tissue (dense regular)

Question 4

Structure of tunica media

Answer 4

• loose connective tissue (containing some smooth muscle fibres)
• Elastic fibres
• also known as the muscular layer

Question 5

Structure of tunica adventitia

Answer 5

• can contain vaso vasorum

- contains CT that merges with surrounding CT

Question 6

When an artery is compared to its corresponding vein what are the differences?

Answer 6

• Artery lumen appears smaller
• Thicker walls
• No valves
• Is more resilient (doesn’t lose its shape)

Question 7

Types of arteries:

Answer 7

Elastic/conducting
Muscular/Distributing
Arterioles/Resistive

Question 8

Elastic conducting arteries consist of:

What do they do?

Answer 8

Aorta, Carotid, Bracheophalic

-conduct blood from the heart so need to be able to withstand changes in pressure

Question 9

Structure of elastic arteries:

Answer 9

• Large tunica media
• Tunica adventitia
• Lots of elastic fibres
• Not much smooth muscle
• 2.5 cm in diameter

Question 10

Muscular arteries:

Answer 10

(distributing)

• most named arteries (e.g. femoral)
• Control speed of blood tailored to organs needs

Question 11

Muscular artery structure

Answer 11

• 0.5mm-0.4cm diameter
• tunica media has lots of smooth muscle
• thick adventitia
• can vasoconstrict and dilate

Question 12

Arterioles structure:

Answer 12

• virtually no adventitia
• can vasoconstrict and dilate
• less than 30 micrometers diameter
• 1 or two layers of smooth muscle in media

Question 13

Arterioles function:

Answer 13

• controls blood flow to organs
• responsible for blood pressure
• can vaso constrict or dilate

Question 14

what is the diameter of capillaries?

Answer 14

8 micrometers

Question 15

What are the three types of capillary?

Answer 15

• sinusoidal
• continuous
• fenestrated

Question 16

Sinusoidal capillaries:

Answer 16

• have holes in the epithelial layer
• incomplete or missing basal lamina
• for exchange of plasma proteins e.g. RBCs
• lined by specialised cells e.g. in the liver where phagocytes engulf RBCs

Question 17

Continous capillaries:

Answer 17

• Most are these
• No gaps between epithelial cells
• found in lungs etc for gas exchange and skeletal muscle

Question 18

Fenestrated capillaries:

Answer 18

-Have small gaps between epithelial cells
-Contain fenestrations/pores
for rapid exchange of molecules (and some small proteins)
-Found in the kidney (glomerulus) and endocrine glands

Question 19

What are the main features of capillary beds?

Answer 19

• Metarteriole
• arteriovenous anastamosis
• pre capillary sphyncters

Question 20

What is a metarteriole?

Answer 20

A continuous vessel linking artery and venous blood supply with many capillaries branching off it
-restricting the blood flow to this can decrease it to the whole capillary bed

Question 21

What is an arteriovenous anastamosis?

Answer 21

A continuous vessel linking artery and venous blood supply with no capillaries branching off it
-blood flow through here can bypass the capillary beds

Question 22

Venules:
function
size
structure

Answer 22

• collect blood from capillary beds and deliver it to small veins
• tunica adventitia is predominant
• very thin walls with essentially just epithelia and basal lamina
• diameter varies around 20 micrometers
• as they get larger you get more smooth muscle in the walls

Question 23

Veins sizes

Answer 23

small - less than 2mm
medium - 2-9mm
large - more than 9 mm

Question 24

Which have higher pressure capillaries or veins?

Answer 24

Capillaries

Question 25

The word describing the link between pressure and blood volume of an artery

Answer 25

capitance

Question 26

The passage that links the metarteriole to the venule

Answer 26

thorouroughfare channel

Question 27

artery that supplies the intestines

Answer 27

Mesentric