Histology

Question 1

What are the 3 layers of basic structure of blood vessel?

Answer 1

Tunica externa
Tunica media
Tunica intima

Question 2

What are the 3 layers of the heart?

Answer 2

Endocardium
Myocardium
Epicardium

Question 3

What does the endocardium and tunica intima contain?

Answer 3

Endothelium, basement membrane and connective tissue

Question 4

What does the myocardium and tunica media contain?

Answer 4

Muscle and elastic tissue

Question 5

What does the epicardium and tunica externa (adventitia) contain?

Answer 5

Fibrous connective tissue
And epicardium has layer of epithelium

Question 6

Describe the endocardium

Answer 6

Lines the heart chambers with simple squamous epithelium sitting on basement membrane
Sits on connective tissue

Question 7

Which layer of the heart forms the valves?

Answer 7

Endocardium

Question 8

Describe the myocardium

Answer 8

Thick middle layer containing cardiac muscle (branching fibres)
Rich capillary bed
Muscle bundles in different planes (spiral) to close down chamber lumen

Question 9

Describe cardiac muscle

Answer 9

Straited, lots of mitochondria and single central nucleus
Myocytes connected by intercalated discs
Has syncytium in which cells function as a unit

Question 10

Describe the epicardium

Answer 10

Outer layer
Simple squamous epithelium, BM and connective tissue
Epithelium makes the visceral layer of pericardium
Contains main branches of coronary arteries

Question 11

Describe the structure of an artery

Answer 11

Thick muscle wall,
smaller and thicker compared to vein
Thin adventitia

Question 12

Describe the structure of veins

Answer 12

Thin muscle wall
Larger and thinner compared to artery
Thick adventitia
Has valves to prevent backflow of blood

Question 13

What are valves in veins?

Answer 13

Endothelial projections into lumen form vein

Question 14

What are the types of arteries?

Answer 14

Elastic, muscular and arterioles

Question 15

Where would you find elastic arteries?

Answer 15

Aorta, common carotid and pulmonary
Large conducting arteries

Question 16

Where would you find muscular arteries?

Answer 16

Coronary arteries, radial and femoral
Distributing arteries

Question 17

Describe elastic arteries

Answer 17

Pressure reservoir. Stretched during systole and maintains pressure during diastole
Recoil and stretchability due to presence of elastic fibres in T. media in layers called laminae

Question 18

In elastic arteries, what are the elastic fibres in T. media secreted by?

Answer 18

Smooth muscle cells

Question 19

Describe muscular arteries

Answer 19

Controls distribution of blood
Thick T. media has smooth muscle cells and no elastic laminae

Question 20

How are elastic fibres concentrated in muscular arteries?

Answer 20

2 well defined sheets
Internal elastic laminae under epithelium
Thin external elastic laminae between T. media and T. adventitia

Question 21

Describe histology of arterioles

Answer 21

Only 1-2 layers of smooth muscle in T. media
No IEL or EEL, or no T. adventitia
Control systemic blood pressure and blood flow to capillaries

Question 22

Describe histology of capillaries

Answer 22

Very thin T. intima, no T. media and no T. adventitia
Blood pressure in capillaries is low and main exchange site

Question 23

What are pericytes?

Answer 23

Incomplete layer of cells surrounding capillary and have contractile properties which control blood flow
Blood pressure is low in capillaries

Question 24

What are the 3 types of capillaries?

Answer 24

Continuous, fenestrated and discontinuous/ sinusoids

Question 25

Explain continuous capillaries

Answer 25

Control what is exchanged, material must pass through cell or between cell
Selective transport mechanisms
Ex. in muscles

Question 26

Explain fenestrated capillaries

Answer 26

Have fenestrations (or pores)
Diaphragms filter molecules by MW and/or charge
Ex. endocrine glands and kidney renal corpuscle

Question 27

Explain discontinuous capillaries

Answer 27

Gaps between endothelial cells (and BM)
Allow free passage of fluid and cells
Ex. liver, spleen and bone marrow

Question 28

What are sinusoids?

Answer 28

Large diameter type of discontinuous capillaries
Found where large amount of exchange takes place
T. intima contains phagocytic cells
Ex. liver

Question 29

What are arteriovenous shunts?

Answer 29

Bypasses capillary beds
Used in skin for thermoregulation

Question 30

Describe the histology of veins and venules?

Answer 30

Thin T. intima, T. media and T. adventitia
Larger and less rounded lumen than arteries

Question 31

Describe the structure of superficial veins?

Answer 31

Thick walled
No surrounding support

Question 32

Describe the structure of deep veins?

Answer 32

Thin walled, surrounding support from deep fascia and muscles
Superficial veins drain into deep veins
DVT can happen

Question 33

Describe lymphatic system

Answer 33

Drains tissue fluid lost from blood capillaries and drains to systemic venous system
Nodes filter the blood and found alongside major arteries
Valves direct flow

Question 34

Describe lymph capillaries

Answer 34

Blind-ended capillaries
Lined by very thin endothelium
No red blood cells in lumen

Question 35

What are anchoring filaments?

Answer 35

Fine collagenous filaments link endothelial cell to surrounding tissue keeping lumen open

Question 36

What is vasa vasorum?

Answer 36

Blood supply to vessels
‘vessels of vessels’

Question 37

Where are lymphatics of blood vessels?

Answer 37

In T. adventitia

Question 38

What nerve supply do blood vessels receive?

Answer 38

Sympathetic and parasympathetic