cardiovascular

Question 1

List the two components of the Cardiovascular system

Answer 1

1. Blood vascular system (Heart -> artery -> capillaries -> vein -> heart)
2. Lymphatic vascular system ( lymphatic capillaries -> Lymphatic organs -> lymphatc vessels -> vein -> heart)

Question 2

Classify the arteries with distribution

Answer 2

The histology of the 3 layers changes as you move through the different classifications. The tunica externa contains the loose connective tissue (elastic) and gives it protection to vessels, this layer will be much thicker in the large vessel. Whereas, in the medium sized artery, the tunica media (middle layer) that normally contains smooth muscle, will be relatively larger to assist with distribution.

1. Large artery
   - Is an elastic artery as they recoil and is the main conducting vessel
   - Needs to be elastic is it this part of the Blood vascular system will be undergoing high blood pressure, immediately after the heart pumps. Aorta must be able to return to its original shape, hence it will contain elastic fibers.
   - e.g aorta
2. Medium sized artery
   - Is a muscular artery as they are the main distributing vessel.
   - e.g renal artery
3. Smallest artery (arteriole)
   - Is a resistance vessel
   - e.g is found at the tissue level

Question 3

Classify the veins and give examples

Answer 3

1. Large vein
   - Creates capacitance and acts as a reservoir
   - Vena Cava
2. Medium sized vein
   - Is a muscular vein
   - e.g renal vein
3. Smallest vein
   - venules
   - found at the tissue level

Question 4

Differentiate between an artery, vein, and capillary

Answer 4

1. An artery will have a thick outer wall, a vein will have a thin layer of muscle and elastic fibers, and the capillary will be made of a single layer of cell.
2. Artery contains a small lumen, the vein contains a large lumen, capillary contains a small lumen.
3. Artery contains thick layer of muscles and elastic fibers, vein has a thin layer of muscle and elastic fibers, capillary has no layers
4. Veins also contain valves, unlike arteries and veins.

Question 5

Classify the types of capillaries and give examples

Answer 5

1. Continuous capillary
   - Made of a single layer of endothelial cells ocnnected to a basement membrane.
   - No trans cellular perforations and the cells are joined by tight junctions, which are non-permeable.
   - Most commonly found in muscle, fat, and nervous tissue.
2. Fenestrated capillary
   - Similar structure to continous capillary but has intracellular perforations called fenestrae and is more permeable than continous capillaries.
   - The fenestrations are pores found in the boundary between endothelial cells
   - Fenestrated capillaries with diaphragms (glycoprotein connection between the endothelial cells) can be found in endocrine glands and the intestine
   - Fenestrated capillaries without diaphragms can be found in the kidney glomeruli
3. Sinusoidal
   - Open spaces bewteen endothelial cells and hence the basement membrane is discontinous
   - It is very permeable and sometimes permits the passage of blood cells between them.
   - Found in liver, spleen, and bone barrow

Question 6

Describe the nutrition and innervation of blood vessels

Answer 6

The vaso vasorum is the primary nutrient blood vessels to other vessels.

The blood vessels also receive autonomic supply and has a sympathetic (vasomotor) and parasympathetic (vasodilator) component

Question 7

Define portal circulation and give some examples

Answer 7

• When blood passes through two sets of capillaries in a closed channel, called portal circulation
• Arterial portal circulation is when blood passes through two sets of capillaries in bewteen arteries
• Venous portal capillaries is when blood passes through two sets of capillaries in veins.

Question 8

Define anastomoses

Answer 8

Communication between vessels (AA, AV, VV)

For example, the arterial arcades in mesenteric arteries or between the R and L coronary arteries.
There are also anastomoses between portal and systemic veins.

Question 9

Define an Arterio-venous shunt

Answer 9

The AVS allows blood to bypass capillary by providing direct routes between arteries and veins
Found in the skin of fingertips, nose, lips, erectile tissue of penis and clitoris

Question 10

Define and give examples of an End Artery

Answer 10

Arteries which have no / few pre-capillary anastomoses not sufficient for collateral circulation.

Types:
1. True end artery
- Have no precapillary anastamoses at arteriolar level
- Example is at th central artery of the retina

2. Functional end artery
   - Have few precapillary anastomses
   - Example is the coronary, cerebral, nutrient artery