Histology

Question 1

What is the functions of the CVS?

Answer 1

Transport oxygen and nutrients to tissues
Transport carbon dioxide and metabolic waste from the tissues
Temperature regulation
Distribution of hormones and immune cells
Reproductive function in maes- penile erection

Question 2

Where is blood distributed at a given moment?

Answer 2

65% peripheral veins
20% heart and lungs
10% in peripheral arteries
5% in capillaries

Question 3

Do the elastic membranes have perforations?

Answer 3

Yes

Question 4

What are pericytes?

Answer 4

Connective tissue cells with contractile properties often found at intervals in capillaries just outside the basal lamina

Question 5

What is the microvasculature?

Answer 5

Small arterioles connect to a post capillary venuole through a network of metarterioles, thoroughfare channels and capillaries.

Question 6

What is a thoroughfare channel?

Answer 6

Allow shunting of blood from the arterial to venous side without passing through capillaries

Question 7

What is a precapillary sphincter?

Answer 7

Smooth muscle sphincter at the beginning of some capillaries to help control flow through the network

Question 8

What is the 3 layer structure of the heart?

Answer 8

Endocardium, myocardium and epicardium

Question 9

What is the structure and function of the epicardium?

Answer 9

Lines the entire surface of the heart including the valves
Endothilium, basal lamina, thin layer of collagen and a layer of dense connective tissue. Some areas have a sub endocardium.

Question 10

What is a sub endocardium and where is it found?

Answer 10

Lose connective tissue containing small vessels, nerves and branches of the impulse conducting system.
Occurs in the ventricular septum and contains perkinje fibres

Question 11

What is the structure and function of the myocardium?

Answer 11

Bundles and layers of contractile cardiac muscle fibres. individual muscle fibres are surrounded by delicate, collagenous connective tissue with a rich network of capillaries.
Single central nucleus and intercollated discs to attach cells together and allow the spread of electrical activity.

Question 12

What is within an intercollated disc in cardiac muscle?

Answer 12

Desomosome to attach intermediate fillaments 
Adherent junctions (zonula adherens) between actin fillaments (microfillaments) 
Gap junctions to allow the spread of depolarisation

Question 13

What is the structure and function of the epicardium?

Answer 13

Outer layer of the heart
Mesothilium, basal lamina, fibroelastic connective tissue and sometimes adipose tissue
Coronary vessels are embedded in the adipose tissue on the surface of the heart

Question 14

What are the 3 layers of pericardium?

Answer 14

Fibrous, perietal and visceral pericardium

Question 15

What makes up the fibrous pericardium?

Answer 15

Tough fibrocollagenous tissue

Question 16

What makes up the serous parietal and visceral pericardium?

Answer 16

Mesothilium with a basal lamia and connective tissue

Question 17

What is contained in the pericardial cavity?

Answer 17

15-50ml of pericardial fluid providing lubrication for contraction

Question 18

What is the fibrous skeleton?

Answer 18

Formed by bands of fibrous connective tissue around the valves, between the atria and between the ventricles.

Question 19

What is the function of the fibrous skeleton?

Answer 19

Supports the valves and provides attachment for cardiac muscle.
Tunnel for the AV bundle is critically important

Question 20

What is the structure of the heart valves?

Answer 20

Outer layer of endothilial cells with a basa lamina
Layer of collagen and elastic fibres
Core of dense irregular connective tissue- lamina fibrosa that is continuous with the fibrous skeleton of the heart

Question 21

How are the leaflet valves anchored to the wall of the ventricle?

Answer 21

Papillary muscles attach to the wall of the ventricles ad chordae tendonae (collagen) attch to the papillay muscles and lamina fibrosa.

Question 22

Are there any blood vessels in the valves?

Answer 22

No

Question 23

What are the 3 types of cardiac muscle cells?

Answer 23

Contractile cells- 99%
Pacemaker cells- generate electrical impulse
Conducting cells- conduct impulse
NB: Pacemaker and conducting cells are specialised muscle cells NOT nerve cells

Question 24

What characterises a pacemaker cell?

Answer 24

Smaller than a contractile cell and embedded in a more extensive matrix of connective tissue
Appear paler as they have few organelles contractile fibres and no T tubules

Question 25

Conducting cells make up the perkinje fibres. Where are they found and what are their features?

Answer 25

Large cells which lie beneath the endocardium in the sub endocardial layer
Abundant in glycogen, no T tubeules or intercollated discs and sparse contractile fibres
Appear pale with a clear centre
Distribute excitatory activity o ventricular contraction contraction occurs apex to base