The Vascular System

Question 1

Describe the different vessel wall layers

Answer 1

Tunica adventitia: thin layer collagen with nerve and bloody supply
Tunica media: smooth muscle with elastic layer
Tunica intima: elastic tissue with inner layer endothelium

Question 2

Describe circulation of coronary arteries and how it provides oxygen to the heart

Answer 2

1. Oxygenated Blood comes in pulmonary artery to left atria through bicuspid valve to left ventricle and up to aorta
2. When heart is in diastole aortic valve closes causing some of the blood to go down coronary arteries
3. This provides oxygen to heart via gas exchange once deoxygenated the blood goes to vena cava via branch of the artery it’s on (either left or right).

Question 3

How does gas exchange take place?

Answer 3

As capillaries have a single layer of endothelial cells gas exchange via diffusion is fast.
Water also moves across the semi permeable membrane depending on hydrostatic and onvotic pressures.

Question 4

Outline what is cardiac output and how to calculate it

Answer 4

CO: is the volume of blood pumped out of heart in one minute

CO (L/min) = stroke volume X heart rate

Factors affecting CO
Reduce strength of contraction of cardiac music
Reduced fillling of left ventricle
Reduced heart rate

Question 5

Outline what is arterial blood pressure and how to calculate it

Answer 5

It is the systolic and diastolic pressure of the heart (abnormal value would be 120/70

Meant arterial BP = CO X total peripheral resistance

Question 6

Outline what is meant by total peripheral resistance

Answer 6

It is the amount of force on circulating blood caused by the vasculature of the body.
So skeletal muscle will contract during movement or muscle tension causing blood vessels contract decreasing size if lumen and increasing pressure of blood flow, making pressure on arterial side higher.

Question 7

Describe the negative feedback loop of how blood pressure is controlled with baroreceptors

Answer 7

Nerve endings on aortic arch (baroreceptors) sense the stretch of carotid sinuses indicating high .BP, so they’ll send message to the brain blocking sympathetic NS stopping increased heart rate.

Question 8

Describe the negative feedback of Renin Angiotensin Aldosterone System (RAAS)

Answer 8

If low blood pressure in kidneys Renin is released into the blood
This converts Angiotensinogen into Angiotensinogen I
ACE (a converting enzyme in the lungs) turns Angiotensinogen I into Angiotensinogen II
This acts on vasoconstriction (skeletal muscle contracts increase BP in veins.
Acts on pituitary gland releasing ADH to increase volume of blood as it increases amount of water retention
Acts on sympathetic NS to increase BP
Adrenal cortex release aldosterone also to increase water retention.