The heart Flashcards
Describe the structure of the heart in mammals.
- Have 4 chambers and a double circulation. (every one circuit of the body, the blood passes through the heart twice)
- Right side of heart receives deoxygenated blood and sends it to the lungs.
- left side receives receives oxygenated and sends to the body.
Why do ventricles have a thicker wall then atrium and why is left ventricles thicker than right.
- Ventricles are thicker as they pump blood out of heart therefore need higher pressure.
- left ventricle has a thicker muscle wall than the right ventricle as it has to pump blood at high pressure around the entire body, whereas the right ventricle is pumping blood at lower pressure to the lungs
describe path way of blood
- Deoxygenated blood coming from the body flows into the right atrium via the vena cava
- Once the right atrium has filled with blood the heart beats and the blood is pushed through the tricuspid valve into the right ventricle
- The walls of the ventricle contract and the blood is pushed into the pulmonary artery through the semi lunar valve.
- The blood travels to the lungs and moves through the capillaries past the alveoli where gas exchange takes place (low pressure necessary on this side of heart– blood is going directly to capillaries which would burst under higher pressure)
- Oxygen rich blood returns to the left atrium via the pulmonary vein
- It passes through the bicuspid valve into the left ventricle
- The thicker muscle walls of the ventricle contract strongly to push the blood forcefully into the aorta and all the way around the body
What are the functions of the valves and how many types of valves are there.
- Basic function = prevent back flow of blood.
1. The atrioventricular valves which separate atria and ventricles. Right side is called tricuspid left side is called bicuspid.
2. Second one = semilunar valves, they are found in the two blood arteries that come out of the top of the heart.
Function of tri and bicuspid valves
They are pushed open when atria contract but when the ventricles contract they are pushed shut to prevent blood flowing back into the atria.
Fuction of semilunar valves
Only two arteries in body that contain valves
1.They open when the ventricles contract so blood squeezes past them out of the heart, but then shut to avoid blood flowing back into the heart
Effect on heart during exercise
- During exercise, muscle cells need more energy as they contracting more, therefore respiring more and need more O2 and glucose and need to get rid of CO2.
to meet this
1. Heart rate increases therefore beating more.
2. Stroke volume increases therefore heart contracts more powerfully, pumping more blood with each beat.
Effect on heart after exercise
- After exercise heart takes few minutes to get back to resting rate to continue to supply muscle cells with oxygen.
This is needed to repay oxygen debt build up during exercise if the muscles respired anaerobically producing lactic acid.
The O2 will react with the lactic acid to produce CO2 and water.
Effect of adrenaline on heart
- Adrenaline is a hormone secreted when we are afraid, stressed or angry
1. Causes heart rate and stroke volume to increase to prepare body for flight or fight.
2. Also diverts blood away from non essential areas of the body (like the digestive system) so that more is available to supply muscles.
What is coronary heart disease.
- The heart is made of muscle cells that require their own supply of blood to deliver them oxygen, glucose and other nutrients and remove carbon dioxide and other waste products.
- The blood is supplied by coronary arteries.
- If the coronary arteries get partially or completely blocked by fatty deposits called ‘plaques’ heart would not respire therefore not allowing it to contract leading to a heart attack.
What are the causes of coronary heart diease
poor diet, stress and smoking\
How does poor diet cause coronary heart disease.
Eating more saturated fat = increases cholestrol levels, increasing chance of building fatty plaques.
How does stress cause coronary heart disease.
When under stress, hormones produce increased blood pressure, increasing chance of a blockage in coronary arteries.
How does Smoking cause coronary heart disease.
Nicotine in cigarette cause blood vessels to be narrower, increasing blood pressure which cause build of fat globules. If it happens in the coronary artery it could cause coronary heart disease.
What is the structure, function and adaptations of arteries
- Carry blood at high pressure away from the heart.
- Carry oxygenated blood other than pulmonary artery.
- Have thick muscular walls containing elastic fibres to withstand high pressure
- Have narrow lumen to maintain high pressure.
* Speed of flow is fast
