Histology

Question 0

Where is the sinoatrial node found?

Answer 0

Junction of the superior vena cava and the right atrium

Question 1

Describe the features of cardiac muscle

Answer 1

Cells are striated
One centrally placed nucleus
Specialised functions called intercalated discs which also act as Z lines
Have gap junctions for cell to cell communication

Question 2

Name some elastic arteries

Answer 2

Pulmonary
Aorta
Brachiocephalic
Subclavian
Carotid
Common iliac

Question 3

What are the blood pressures during systole and diastole of the elastic arteries?

Answer 3

Systole: 120mmHg
Diastole: 70-80mmHg

Question 4

What is in the tunica media?

Answer 4

External elastic lamina
Elastic membranes
Smooth muscle cells
Collagen

Question 5

Describe the walls of arterioles

Answer 5

1-3 layers of smooth muscle cells in the tunica media
Only larger ones have a thin, elastic lamina
External elastic lamina is absent
Tunica adventitia is scant

Question 6

Which arteries arise from the aorta?

Answer 6

The brachiocephalic, common carotid and left subclavian

Question 7

What does the aorta bifurcate into in the abdomen?

Answer 7

The left and right common iliac arteries

Question 8

How much blood does the CVS need to deliver to tissues?

Answer 8

5-25L/min

Question 9

What blood flow does the brain require?

Answer 9

0.75L/minute

Question 10

How is flow contolled?

Answer 10

Arterioles and pre-capillary sphincters

Question 11

What is the blood volume?

Answer 11

5L

Question 12

How much blood is in arteries and arterioles?

Answer 12

0.55L

Question 13

How much blood is in capillaries?

Answer 13

0.25L

Question 14

How much blood is in veins?

Answer 14

3.35L

Question 15

How much blood is in the heart and lungs?

Answer 15

0.85L

Question 16

What is the function of arterioles?

Answer 16

Regulate amount of blood reaching tissues

Regulate blood pressure

Question 17

What type of arteries are arterioles

Answer 17

Muscular

Question 18

How high is blood velocity in capillaries? Why?

Answer 18

At its lowest

Allows time for exchange with surrounding tissues

Question 19

Diameter of capillaries?

Length of capillaries?

Answer 19

7-10 μm

Less than 1mm

Question 20

Describe continuous endothelial layer

Answer 20

Cells joined by tight/occluding junctions

Question 21

Where are capillaries with continuous endothelium found?

Answer 21

Nervous, muscle and connective tissues

Question 22

Describe fenestrated endothelium in capillaries

Answer 22

Has interruptions in the endothelium and bridged by a thin diaphragm.

Question 23

Where is fenestrated endothelium found?

Answer 23

Gut, endocrine glands and the renal glomerulus

Question 24

Describe sinusoidal endothelium

Answer 24

``` Larger diameter (30-40 μm) and slower blood flow. Gaps exist in the walls allowing whole cells to move between blood and tissue. ```

Question 25

Where are sinusoidal capillaries found?

Answer 25

Liver Spleen Bone marrow

Question 26

What are pericytes?

Answer 26

Form a branching network on outer surface of endothelium | Can divide into muscle cells or fibroblasts during angiogenesis, tumour growth or wound healing

Question 27

Which veins do not have semi lunar valves?

Answer 27

Those less than 1mm in diameter | Those found in the thoracic and abdominal cavities

Question 28

Characteristics of the tunica intima in elastic arteries?

Answer 28

Endothelial cells with long axes parallel to the long axis of the artery Narrow sub-endothelium of connective tissue with discontinuous internal elastic lamina

Question 29

Features of the tunica media of elastic arteries?

Answer 29

40-70 fenestrated elastic membranes Smooth muscle cells and collagen between these lamellae Thin external elastic lamina may be present

Question 30

What is in the tunica adventitia of muscular and elastic arteries?

Answer 30

Vaso vasorum Fibroelastic connective tissue Lymphatic vessels Nerve fibres

Question 31

Features of tunica intima of muscular arteries?

Answer 31

Endothelium Sub endothelial layer Thick internal elastic lamina

Question 32

Features of tunica media of muscular arteries?

Answer 32

40 layers of smooth muscle cells connected by gap junctions for coordinated contraction Prominent external elastic lamina

Question 33

What type of nerve fibres stimulate vasoconstriction? What is the neurotransmitter?

Answer 33

Sympathetic | Noradrenaline

Question 34

When is an artery considered to be an arteriole?

Answer 34

When its diameter is less than 0.1 mm

Question 35

How many layers of smooth muscle cells do arterioles have?

Answer 35

1-3

Question 36

What is a pre-capillary sphincter?

Answer 36

A smooth muscle cell that encircles the endothelium of a capillary arising from a metarteriole

Question 37

What is re permeability of post capillary venules compared to capillaries?

Answer 37

More permeable

Question 38

Which way does fluid flow in a post capillary venule? ie out of or into the vessel through the wall?

Answer 38

Fluid tends to drain in, due to low pressure

Question 39

Diameter of venules?

Answer 39

Up to 1mm

Question 40

How do veins compare to their accompanying artery?

Answer 40

Larger diameter | Thinner wall with more connective tissue and fewer elastic and muscle fibres

Question 41

What is the order of vessels that blood passes through?

Answer 41

``` Large arteries (elastic) Medium arteries (muscular) Arterioles Metarterioles Capillaries Post capillary venules Venules Medium veins Large veins ```

Question 42

What is found in the tunica adventitia of arteries?

Answer 42

Thin layer of fibrous connective tissue Vaso vasorum Lymphatic vessels Nerve fibres