Circulatory System Flashcards
What does the cardiovascular system do?
Circulates and transports nutrients, oxygen, carbon dioxide, hormones, and blood cells to and from cells in the body
Fights disease, stabilises temperature, pH, and helps maintain homeostasis
Three main components of the CVS:
Heart, blood and blood vessels
What is pulmonary circulation?
A loop through the lungs where blood is oxygenated
What is the systemic circulation?
A loop through the rest of the body to provide oxygenated blood and receive deoxygenated blood.
How much blood does an average adult have?
5 litres.
2 litres of red cells
3 litres of plasma
Where is the blood distributed?
3.25 litres in the veins
1 litre in the heart and lungs
- 5 litres in the peripheral arteries
- 25 litres in the capillaries
What is an end artery?
A terminal artery supplying all or most of the blood to a body part without significant collateral circulation.
What is systole?
Left ventricular contraction causes the blood pressure in the aorta to rise to ~120mmHg. The walls of the aorta stretch.
What is diastole?
The aortic semilunar valve closes. Walls of the aorta recoil maintain pressure and moving blood towards the heart. Aortic pressure drops to 70-80mmHg
Three layers of the walls of arteries and veins:
Tunica intima
Tunica media
Tunica adventitia
What is the tunica intima?
Endothelium
Subendothelial layer
Thick internal elastic lamina
What is the tunica media?
40 layers of smooth muscle cells
Prominent external elastic lamina
What is the tunica adventitia?
Thin layer of fibroelastic connective tissue
Lymphatic vessels
Nerve fibres
What are arterioles?
Arteries with a diameter less than 0.1mm
Only 1-3 layers of smooth muscle in tunica media
What are metarterioles?
Arteries that supply blood to capillary beds
