Histology Of Blood Vessels And Nerves

Question 1

What are the three layers of arteries and veins?

Answer 1

Intima
Media
Adventitia

Question 2

Do arteries and veins often run side by side?

Answer 2

Yes

Question 3

How can you immediately tell the difference between an artery and vein?

Answer 3

The artery has a thicker, more muscular wall and appears circular
The vein has a larger diameter, with a thinner wall and appears more irregular in shape
Veins have valves

Question 4

Describe the intima layer

Answer 4

The thinnest layer composed of endothelium and a small amount of elastic tissue

Question 5

What separates the intima layer from the medial layer?

Answer 5

A wavy internal elastic lamina (it glistens)- which is a tube of elastic tissue

Question 6

What is the media layer mostly composed of in arteries?

Answer 6

Smooth muscle arranged circumferentially

Question 7

In large muscular arteries e.g. aorta what is also present?

Answer 7

An external elastic lamina between the media and adventitia layers

Question 8

What is the adventitia mainly composed of?

Answer 8

Strands of collagen and elastin fibres

Question 9

Which arteries contain the most elastic fibres?

Answer 9

Those nearer the heart

Question 10

What is the main differences between arteries and arterioles?

Answer 10

Arterioles are thinner in diameter, never contain an external elastic lamina and have less smooth muscle in their media

Question 11

Describe venules

Answer 11

Very thin walled with little of no muscle, often their endothelium is just reinforced by connective tissue

Question 12

Describe large lymphatic vessels

Answer 12

Irregular outline
Thin walls with a mixture of collagen and elastin with few smooth muscle fibres
Filled with amorphous plasma (stains pink in H&E)
Contain valves

Question 13

Describe capillaries

Answer 13

Walls are just endothelial cells and their basement membrane
Pericytes regulate their diameter

Question 14

What are the two types of capillaries?

Answer 14

Continuous- transport across is by diffusion or pinocytosis

Fenestrated- products pass freely through pores

Question 15

What are the two parts of the nervous system

Answer 15

Central- contains most of the cell bodies

Peripheral-contains mostly axons

Question 16

What are the supporting cells in the (1) CNS (2) PNS

Answer 16

(1) oligodendrocytes

(2) Schwann cells

Question 17

What is responsible for anterograde (forward) and retrograde (backward) movement of organelles (especially vesicles) along a nerve cell?

Answer 17

A complex cytoskeleton

Question 18

Other than the CNS where can nerve cell bodies also be found?

Answer 18

Dorsal root ganglia (sensory neurone cell bodies)
Sympathetic ganglia alongside the spinal cord
Parasympathetic ganglia embedded in the organs they innervate

Question 19

How can you distinguish between a myelinated axon or unmyelinated axon?

Answer 19

In a myelinated axon: the Schwann cells only surround one axon and are a lot thicker
In an unmyelinated axon: the Schwann cell surrounds multiple axons and the wall is much thinner

Question 20

What does epineurium surround?

Answer 20

Multiple nerve fascicles and blood vessels that supply the nerve
Forms nerve fibres

Question 21

What does perineurium surround?

Answer 21

A single fascicle (bundle of axons)

Question 22

What does endoneurium surround?

Answer 22

A single axon, it is the connective tissue present between individual axons

Question 23

What is the problem with observing the myelin sheath?

Answer 23

Normally the lipids contained within the myelin sheath are extracted during processing

Question 24

How can the myelin sheath be preserved?

Answer 24

Using osmium tetroxide, in which case they appear brown

Question 25

How can you recognise a peripheral nerve cut longitudinally in osmium tetroxide stain?

Answer 25

Gaps between brown myelin sheath (nodes of ranvier)

Question 26

How can you distinguish between motor neurone cell bodies in the CNS and sensory cell bodies in the dorsal root ganglion?

Answer 26

Motor neurone cell bodies have processes arising from them and are stained brown
Sensory cell bodies are more circular and stain pink

Question 27

What is the life span of erythrocytes?

Answer 27

120 days