L12 Coronary Circulation and Tissue Perfusion

Question 1

What is the main source of energy in the heart?

Answer 1

2/3 = Fat

Question 2

How is pressure calculated?

Answer 2

Pressure = Flow * Resistance

Question 3

How is a blood vessel structured?

Answer 3

The inner endothelial layer is found in all blood vessels. Above the endothelium is the tunica intima. Atherosclerosis occurs above the endothelial layer in the intima. The endothelial lining is important in terms of protection. There is a muscular media layer and an outer adventitia where there is a neural and blood supply. Muscular arteries are found away from the heart and so are required to maintain flow using resistance. The resistance vessels are upstream of the capillaries.

Question 4

What is the use of nitrous oxide in the heart?

Answer 4

The endothelium of blood vessels uses nitric oxide to signal the surrounding smooth muscle to relax, thus resulting in vasodilation and increasing blood flow. Nitric oxide is made by endothelial cells. Sheer stress of the endothelial, which happens in exercise, causes nitric oxide production. If you do not exercise, it does not produce nitric oxide and the arteries cannot dilate as well leading to hypertension and coronary heart disease.

Question 5

How is the lumen of vessels controlled?

Answer 5

Angiotensin II is a vasoconstrictor and bradykinin and histamine are vasodilators, part of an inflammatory reaction.

Question 6

What is the difference between pitting oedema and non-pitting oedema?

Answer 6

This is pitting oedema. This is caused by water leakage.

Non-pitting oedema is caused by protein that is leaked into the space. This can cause in lymphedema due to lymphoma.

Question 7

What are the 3 cardinal features of angina?

Answer 7

• Relieved by rest and relieved by GTN which opens blood vessels
  
  • Pain onset by exercise
    Chest pain

Question 8

How can menopause lead to chest pain?

Answer 8

Post menopausal women, the ovaries stop making oestrogen and the endothelial are less relaxed. This results in spasm. This is a dynamic effect. Due to lack of relaxation of the endothelium. People are typically under stress. They hyperventilate, increased pH , calcium influx causing spasm. This leads to crushing chest pain. The treatment for this is vasorelaxation substances which relax the blood vessels even during stress.