L1: Anatomy Cardiovascular System

Question 1

What is the function of the cardiovascular system?

Answer 1

The basic function of the cardiovascular system is to exchange nutrients in order to maintain a constant internal environment. It also provides an opportunity for hormones to be distributed.

Question 2

How can the CVS be divided in terms of circulation?

Answer 2

The systemic circuit and the pulmonary circuit.

The systemic circuit to and from the body. It delivers oxygenated blood and removes waste. The pulmonary circuit is used to take oxygen to and from the lungs for oxygenation.

Question 3

How can the CVS be divided functionally?

Answer 3

The conducting portion and the exchange portion.

The conducting portion is made up of vasculature that transport blood around the body to the relevant areas. The exchange portion is made up of capillary beds and are the site fo gases exchange.

Question 4

How does blood flow through the chambers of the heart?

Answer 4

Blood enters the right atrium via the superior and inferior vena cava. This then flows into the right ventricle and is pumped out to the lungs via the pulmonary trunk. The pulmonary trunk branches out into the right and left pulmonary artery.

Blood enters the left ventricle through sth pulmonary veins - there are 4. It then moves down into the left ventricle and is pumped tho the body through the aorta.

We then branch out from the aorta to form small arteries that send blood to the limbs and the viscera. These will get smaller to arterioles and eventually to capillary beds. The capillary beds are within the organ and the site of exchange. Away from the heart, the vessels get thinner and thinner.

Question 5

Where does the coronary sinus empty?

Answer 5

The right atria

Question 6

What is the fossa ovalis?

Answer 6

The indentation in the wall known as the fossa ovalis - this used to be a hole in embryology. It used to be a forona ovale. This is used to bypass the lungs as a foetus. When developing in the womb you get oxygenated blood from the placenta. As a result the foetus only requires a small amount of oxygenated blood from the lungs to keep the tissue alive.

Question 7

How does the texture of the atria vary?

Answer 7

There is a roughened part on the muscles compared to the smooth wall of the atrial wall. This means the atria comes from two different embryological origins.

Question 8

How do the papillary muscles attach to the AV valve?

Answer 8

There are muscular elevations known as Trabeculae carneae on the muscular walls. There are further elevations from this muscle known as Papillary muscles. The attachment of the papillary muscles are attached to the tricuspid valves by the chordae tendineae.

Question 9

What is the function of the papillary muscles?

Answer 9

The papillary muscles are muscles located in the ventricles of the heart. They attach to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae and contract to prevent inversion or prolapse of these valves on systole (or ventricular contraction).

Question 10

What is the difference between the left and right atria?

Answer 10

The left atria is smoother than the right atria.

Question 11

What vessels branch from the ascending aorta?

Answer 11

The coronary arteries.

Question 12

What vessels branch from the aortic arch?

Answer 12

The brachocephellic artery, the carotid artery and the subclavian artery.

Question 13

Name the major branches of the coronary artery.

Answer 13

There is a left and right coronary artery. The left coronary artery branches into the left inter ventricular anterior artery (the left descending anterior artery) and the circumflex artery.

The right coronary artery supplies blood to the right ventricle, the right atrium, and the SA (sinoatrial) and AV (atrioventricular) nodes, which regulate the heart rhythm. The right coronary artery divides into smaller branches, including the right posterior descending artery and the acute marginal artery.

Question 14

What is the effect of a blockage of a coronary artery?

Answer 14

Coronary arteries are functional end arteries. There is not a lot of overlap in the areas in which they supply and so if the flow is blocked, that particular area of the heart will not receive a lot of blood an so the tissue will die.

Important: sudden blockage may lead to Ischaemia i.e.. Reduced/inadequate blood supply
This can lead to Myocardial Infarction. An infarction means that the blood delivered to the tissue is reduced, leading to necrosis.

Question 15

What are the different types of branches from the aorta?

Answer 15

A = Ventral, unpaired arteries to gastrointestinal tract (e.g.: coeliac trunk)
B = Paired, arteries to paired internal organs (e.g.: kidneys i.e. paired renal arteries/gonads)
C = Paired, segmental arteries to body wall (e.g.: intercostal arteries)

Question 16

At what stage does the aorta pass through the diaphragm?

Answer 16

The aorta passes through at the aortic hiatus at T12.

Question 17

At what stage does the oesophagus pass through the diaphragm?

Answer 17

T10

Question 18

At what stage does the vena cava pass through the diaphragm?

Answer 18

T8

Question 19

What is collateral circulation? How does this occur?

Answer 19

Blood is diverted through dilated smaller vessels to bypass the obstruction. This can develop between proximal and distal aorta via intercostal and internal thoracic arteries. There is an increase in pressure of the aorta due to a blockage causing smaller arteries to dilate. Blood passes through the brachiocephalic trunk, subclavian and the carotid. The subclavian gives rise to the internal intercostal arteries which gives rise to anterior intercostal muscles.

The anterior intercostal muscles anastomose with the posterior intercostal muscles (which arises form the aorta). With a collateral blood supply there is an increased blood supply in the subclavian and so internal intercostal artery. Blood now in the anterior intercostal artery will then anastomose with the posterior intercostal artery and drain back into the aorta so the rest of the body can be supplied.

Question 20

What arteries supply the limbs?

Answer 20

• The lower limb is supplied by the external iliac

- The upper limb is supplied by the subclavian

Question 21

Give the features of deep veins.

Answer 21

Deep veins are usually duplicated or triplicated.
• Surround corresponding artery (accompanying veins)
• Radial artery = Radial vein
• Use arterial contraction and valves to aid venous return known as a Arteriovenous pump
• Helps to maintain core body temperature using a counter-current heat exchanger

Question 22

What is the lymphatic system? How does it drain into circulation?

Answer 22

Lymphatic plexuses (amongst capillaries
->
Lymphatic vessels (alongside arteries)
->
Lymph nodes
->
Thoracic duct or
right lymphatic duct
->
Venous system

Thin wall tubes that transport interstitual fluid, bacteria, cellular debris & whole cells
(lymphocytes).

Question 23

What is anastomosis?

Answer 23

Anastomosis - two vessels that supply the same area. They can either meet or anastomose theoretically where by they supply the same area but do not meet.

Question 24

What arteries, other than the anterior intercostal arteries, branch from the internal intercostal muscle?

Answer 24

Superior epigastric and muscophrenic artery