Cardiovascular System

Question 1

What is the site of the heart?

Answer 1

Lies behind sternum & costal cartilage, extending from 2nd to 6th

Question 2

What on the two sacs covering the heart.

Answer 2

Fibrous pericardium
Serious pericardium

Question 3

What are the types of circulation

Answer 3

Systemic _ pulmonary_ portal

Question 4

Define arteries.

Answer 4

Vessels which carry blood from the heart
Larry oxygenated blood except pulmonary artery & umbilical arteries

Question 5

Define arterial anastomosis & functions & types

Answer 5

Connection between arteries present mainly around joints
Functions:
→ increases blood supply to some organs
→ equalizes pressure in communicating arteries
→ maintains blood flow to an area if itsmain artery is obstructed

Types: end-to-end / by terminal arterioles / by conversion

Question 6

Clinical importance of anastomosis

Answer 6

All large arteries that cross over a joint are liable to be kinked during movements of the joint, however, the distal flow of the blood is not interrupted because an adequate anastomosis is usually between branches of the arteries that arise both proximal and distal to the joint.

Sudden closure of the main artery proximal to the anastomosis, such as in faulty ligation, will lead to the death of the part of the limb distal to the artery because anastomosis does not open in sudden closure.

Question 7

What ate end arteries?

Answer 7

They are arteries which do not anastomose with adjacent arteries are called the end arteries and their obstruction will lead to death (necrosis) of the tissues which are supplied by them

1) Central retinal artery which supplies the retina.

2) Renal artery which supplies the kidney.

3) Splenic artery which supplies the spleen.

4) Central branches of cerebral arteries (brain)

5) Pulmonary arteries

Question 8

Factors which help venous return

Answer 8

From upper part of the body venous blood is drained mainly by gravity

II. From lower part of the body

A- from the lower limb:

1. Venous valves.
2. Arterial pulsations.
3. Muscular contractions (muscle pump).
4. Deep fascia surrounding the muscle groups
5. Negative intrathoracic pressure drawing blood from the abdomen, head and neck into thorax.

B-from abdomen, pelvis and thorax venous return by suction mechanism of negative intrathoracic pressure.

Question 9

What are the arterio- venous connections

Answer 9

Arteries and veins are connected by one of the following structures:

1. Capillaries: with narrow uniform diameter.
2. Sinusoids: with wide irregular diameter with dilatations and constrictions
3. Arteriovenous shunt: between small arteries and accompanying veins.

Question 10

State site, functions & characters of arteriovenous shunt

Answer 10

Sites:
1. External ear, nail bed and palmar aspects of digits.
2. Tongue.
3. Thyroid gland.
4. Penis.
5. Alimentary tract.

Characters: Straight or coiled, surrounded by a thick muscular coat and supplied by sympathetic fibers which control its opening and closure

Functions:

1. Regulation of body temperature and local heat: when it opens, blood will pass from the artery to the vein decreasing the local heat.
2. Regulation of food absorption.
3. Play a role in erection.

Question 11

State the clinical importance of arteriovanous shunt.

Answer 11

Varicose veins:
A varicosed vein is one that has a larger diameter than normal and is elongated and tortuous. It has many causes, including hereditary weakness of the vein walls, incompetent valves, and elevated intra- abdominal pressure as a result of multiple pregnancies or abdominal tumors. As result of high pressure the venous blood escapes from the deep to superficial veins and produces varicosity. Varicose veins commonly occur in the lower limb.

Stagnation:
Stagnation of blood in the varicose veins may cause thrombosis e.g. deep venous thrombosis (DVT) in the calf muscles