2 Blood and circulation page 70-79, 81-83 Flashcards
What does blood transport?
- Oxygen from the lungs to all other parts of the body.
- Carbon dioxide from all parts of the body to the lungs.
- Nutrients from the gut to all parts of the body.
- Urea from the liver to the kidneys.
What is a single circulatory system?
The blood is pumped from the heart to the gas exchange organ and then directly to the rest of the body.
What is a double circulatory system?
The blood is pumped from the heart to the gas exchange organ, back to the heart and then to the rest of the body.
How is the heart adapted to its function?
- The left ventricle pumps blood to the whole body while the right ventricle pumps only to the lungs. This requires more pressure so the wall of the left ventricle is much thicker due to the pressure.
- Valves prevent the backflow of blood.
- Walls of the heart are made with cardiac muscle, so it can contract and relax continuously without getting fatigued.
- Walls of the atria are thin and can be stretched to receive blood and can also contract enough to push the blood out.
What do arteries do?
Carry blood away from the heart.
Pulmonary artery, aorta
What do veins do?
Carry blood to the heart.
What do capillaries do?
Carry blood through organs, through the organs. Linking arteries and veins.
What is coronary heart disease caused by?
Blocked coronary arteries (saturated fats).
What factors make coronary heart disease more likely?
- Heredity.
- High blood pressure.
(Puts more strain on the heart) - Diet
- Stress.
- Lack of exercise.
What happens to our heart rate when we exercise?
It increases.
Why does this happen?
When exercising, our cells need more oxygen to respire. So the heart pumps more blood around the body to deliver this energy.
Why does this happen (nerves)?
The receptors in the aorta and carotid artery detect this increase in carbon dioxide and send nerve impulses to the medulla. The medulla responds by sending nerve impulses along the accelerator nerve.
What does the accelerator nerve do?
Increases the heart rate and makes it beat with more force.
What happens to out heart rate when we are afraid or scared?
It increases.
Why does this happen?
It supplies extra blood to the muscles, enabling them to release extra energy through aerobic respiration. This is apart of the bodys’ ‘fight or flight’ response to danger. It is triggered by the secretion of the hormone adrenaline from the adrenal glands.
Who are these changes in heart rate controlled?
Through the medulla in the brain.
How are arteries adapted?
- Thick muscular walls, helps to control the blood flow by dilating and constricting.
- Elastic tissue, allows them to recoil and spring back into shape by maintaining the high blood pressure.
How are veins adapted?
- They contain valves which prevent the backflow of blood.
- They don’t have as thick walls as they don’t have such high pressure in them when they are carrying around blood.
How are capillaries adapted?
- They are very small in order to fit between cells and allow materials to pass through their walls easily.
- One cell thick so the diffusion of materials into and out of the blood can be easier- proving a shorter distance.
- Oxygen can diffuse out of them very easily as the red blood cells are very close to the capillaries walls.
What is the composition of the blood?
- Plasma.
- Red blood cells.
- White blood cells.
- Platelets.
What are examples of white blood cells?
- Phagocytes.
- Lymphocytes.
What is plasma?
Liquid part of blood, mainly water.
What is plasmas function?
Carries the blood cells around the body; carries dissolved nutrients, hormones, carbon dioxide and urea; also distributes heat around the body.
What are red blood cells?
Biconcave disk-like cells with no nucleus so more blood can bind to them.
