Anatomy of the cardiovascular system

Question 1

What terms are commonly used in anatomy?

Answer 1

• Superior (rostral)- towards the head
• Inferior (cadual)- towards the feet
• Anterior- towards the belly (body facing sideways on)
• Posterior- towards the bum (sideways on)
• Middle line down the centre running down the spinal cord- medial
• Lateral- Anything towards the exterior (away from the medial)

Question 2

What is the pericardium- function and organisation?

Answer 2

The heart sits in the middle of the chest (slightly towards the LHS). It sits in a bag (pericardium). There are 5 layers between the blood in the chambers and the outside of the heart:

1. Endocardium- one cell thick layer which is the interface between the heart and the blood
2. Myocardium- Thick layer of cardia muscle cells
3. Visceral pericardium- the epicardium: a layer of serous tissue between the myocardium and pericardial space
4. Parietal pericardium- a layer of serous tissue linng the fibrous pericardium and facing the pericardial space
5. Connective tissue to protect the heart and hold its position

Question 3

What are the 4 chambers of the heart?

Answer 3

• Left atrium- recieves oxygenated blood from the lungs from pulmonary veins
• Left ventricle- gives out oxygenated blood to the body by the aorta
• Right atrium- recieves deoxygenated blood from the body via the vena cava
• Right ventricle- sends deoxygenated blood to the lungs by the pulmonary artery

Question 4

Label this diagram

Answer 4

NB:

• Mitral valve is another word for bicuspid valve
• Aortic valve is the SL valve on the LHS
  The pulmonary valve is the SL valve on the RHS
• Valves are held in place by chordae tendineae (tendonous chords) which are connected to papillary muscle.
• There are multiple pulomnary arteries entering the LHS
• There is an inferior (coming from the bottom) and superior (coming from the top) vena cava, entering the right atrium.
• The left ventricle heads up into the aortic arch

Question 5

What are the 4 valves in the heart and how many cusps do they have?

Answer 5

• Tricuspid valve- 3 cusps- on the RHS between the right atrium and the right ventricle
• Mitral valve (bicuspid valve)- 2 cusps- on the LHS between the left atrium and the left ventricle. The mitral valve is not equally biscuspid (more one than the other)
• Aortic valve- semilunar valve (3 cusps) between the left ventricle and the aortic arch
• Pulmonary valve- semilumar valve (3 cusps) between the right ventricle and the pulmonary artery

Question 6

What are the layers of a blood vessek?

Answer 6

1. Tunica externa (outer layer)- outer connective tissue layer. loosely formed layer of elastic and collagenous fibres along the length of the vessel. Provides mechanical strength.
2. Tunica media (the middle layer)- consists of cocentric smooth muscle cells with fibres of collagen and elastin.
3. Tunica intima- flat layer of endothelium cells overlying a thin layer of connective tissue. The endothelium cells are in direct contact with the blood

In some vessels, the external elastic lamina is inbetween teh tunica externa and tunica media

Similarly, the internal elastic lamina lies inbetween the tunica media and the tunica intima

Question 7

Describe the histology of all the blood vessels

Answer 7

Artery- conduit vessels- carry blood from one location to the other- lots of elastic and collagenous tissue

Arteriole- resistance vessels because they control flow into the copious numbers of capillary beds. lots of smooth muscle

Capillary- mainly all endothelium layers. They are known as exchange vessels because they are responsible for gas exchange, absorption and secretion

Venule- bit between capillary and vein. Mainly collagenous tissue

Veins- capacitance vessels- because they contain the majority of blood at any given time. No elastic tissue- mainly collagenous tissue and some smooth muscle. they have valves

Question 8

Describe coronary circulation (arteries)

Answer 8

The blood supply of the heart comes from the right and left coronary arteries which arise from the root of the aorta.

The right coronary artery sends descending branches to the right ventricle and to a part of the septum

The left coronary artery branches extensively to provide a rich blood supply to the left ventricle as well as the septum. The left ventricle has the biggest blood supply.

The left circumflex goes around the back of the heart.

Question 9

Describe coronary circulation (veins)

Answer 9

The coronary sinus recieves four major tributaries: the great, middle, small and posterior cardiac vein.

great- begins at the apex of the heart.

The coronary sinus drains into the bottom of the right atrium.

Question 10

Arterial network from the aorta

Answer 10

The ascending arch of the aorta has three arteries diverging greatly from the aorta.

There are 3 trunk vessels- primary branches that come out of the arch. They are 1) Brachiocephalic 2) left common carotid 3) left subclavian.

These trunks then branch/ bifurcate into smaller arteries. For instance, the brachiocephalic bifurcates into the right subclavian and the right common carotid

Question 11

Venous network

Answer 11

Most veins converge and coalesce into the vena cava. Most veins are named taking into account the organ drained, it anatomical location and its side of the body.

Just know some of the main ones:

Inferior/ superior vena cava

Femoral vein

Subclavian vein

Radial/ulna vein

Hepatic and renal veins coming off the inferior vena cava

Question 12

How is a pre-transplant heart connected into the organ care system

Answer 12

• A cannula securely collects blood from the pulmonary artery
• Blood is pumped into the aorta
• The vena cava is clamped
• The pulmonary veins are not clamped

The RHS is airtight and the blood is pumped into the aorta because blood flow is blocked by the aortic valve and pushed into coronary arteries.

A drainage vent should be put in place into the apex of the left ventricle- this is done by the pulmonary vein, through the LA and mitral valve.