Topic 1 Flashcards
What are the three types of circulatory system?
Open
Closed, single
Closed, double
Describe open circulatory systems
They partly depend on diffusion, as the heart pumps blood into cavities surrounding organs, leaving substances to diffuse in and out. Only occurs in small animals, like insects, because diffusion is inefficient
Describe closed circulatory systems
More efficient than open because blood travels quicker through tube, as it’s under higher pressure. It is found most animals
Describe single circulatory systems
Blood goes through the heart once in one circulation. It mainly happens in fish. The heart pumps deoxygenated blood to gills, where gaseous exchange occurs. The newly oxygenated blood then travels to the rest of the body
Describe double circulatory systems
Blood goes through the heart twice in one circulation. The right ventricle pumps dexygenated blood to the lungs, where gaseous exchange takes place. The newly oxygenated blood returns to the heart, where it receives an extra boost to reduce the time taken to got round the body
What are three main types of blood vessels in mammals?
Arteries
Veins
Capillaries
What is the function of arteries?
To take blood away from the heart to the rest of the body. Apart from the pulmonary artery, all arteries carry oxygenated blood
How are arteries adapted to their function?
Thick walls- lots of muscle and elastic tissue to cope with the high pressure
Endothelium is folded- allows lumen to expand to cope with the high pressure
No valves- high pressure keeps blood going in the right direction
What is the function of veins?
To take blood back to the heart from the body. Apart from the pulmonary vein, all veins carry deoxygenated blood
How are veins adapted to their function?
Wide lumens- very little muscle or elastic tissue because the blood is under low pressure
Valves- to stop blood flowing backwards
What is the function of capillaries?
The location of metabolic exchange
How are capillaries adapted to their function?
Walls are only one cell thick- speeds up diffusion in and out of capillaries
Network of capillaries- increase the surface area for exchange
Which ventricle has more muscular walls and why?
Left ventricle, in order to pump blood around the body
What is the function of atrioventricular valves?
To stop blood flowing back into atria from ventricles when ventricles contract. Cords attach AV valves to ventricles, which stops them being forced into atria when ventricles contract
Function of sumilunar valves?
To stop blood flowing back into the heart when the ventricles relax
What are the three stages in the cardiac cycle?
Atrial systole/ventricular diastole
Ventricular systole/atrial diastole
Cardiac diastole
What happens during atrial systole/ventricular diastole ?
The ventricles are relaxed. The atria contract, meaning the volume inside decreases and the pressure increases. This pushes blood into the ventricles, through the open AV valves
Describe what happens during ventricular systole/atrial diastole
Ventricles contract, causing the volume to decrease and the pressure to increase. AV valves are forced shut because the pressure is higher in ventricles than atria. Semi-lunar valves are forced open, blood is forced out of the heart through aorta/pulmonary artery
Describe what happens in cardiac diastole
Whole heart is relaxed. Semi-lunar valves forced shut due to pressure in pulmonary artery/aorta. Blood returns to the heart and the atria begin to fill. The pressure in the atria is higher than in ventricles, so AV valves open, blood passively into ventricles
How can the endothelium be damaged?
High blood pressure, toxins in tobacco
Define endothelial damage
When damage to the endothelium means it can’t function properly
Describe the process of atherosclerosis
- damage to the endothelium causes an inflammatory response
- white blood cells, as well as lipids, move to the area and clump together under endothelium
- more WBC, lipids, and connective tissue build up over time to form atheromas, fibrous plaques
- this hardens artery walls
Why does the build up of atheromas result in a dangerous negative feedback system?
The plaques make the arteries narrower, restricting blood flow. This increases blood pressure, which makes it more likely for another plaque to form
Suggest another reason why the formation of atheromas is bad.
The amount of blood arteries can carry reduces, so they can’t supply enough oxygen or nutrients to tissues
Why does atherosclerosis only happen in arteries?
The blood in arteries is under much higher pressure than in veins.
