Transport in Humans

Question 1

Blood
Q1: Structure of red blood cells, life, where are they produced?
Q2: What happens to RBCs after 4 months?

Answer 1

Q1: - tiny, disc like shape
- made of spongy cytoplasm enclosed in elastic cell membrane
- their cytoplasm has haemoglobin: a red pigment consisting of a protein combined with iron
- no nucleus
- life: about 4 months
- made by red bone marrow of ribs, backbone, breastbone.
Q2: - broken down by the liver
- haemoglobin: broken down to a yellow pigment called bilirubin, which is excreted in the bile
- iron: stored in the liver

Question 2

Q3: Structure of white blood cells, types, where do they mature?
Q4: What are platelets?
Q5: How do platelets clot blood?

Answer 2

Q3: have nuclei and are bigger than RBCs
- Phagocytes: kill by ingesting. irregular shape, granular cytoplasm (can escape from capillaries into tissues by squeezing between the cells of capillary walls)
- lymphocytes: kill by producing antibodies, circular shape, granular
- undergo a maturation and development process in the thymus gland, lymph nodes and spleen
Q4: Colourless blood cells that help blood clot, made in the bone marrow.
Q5: by converting fibrinogen to fibrin.

Question 3

Heart
Q1: Flow of blood through the heart?
Q2: Function and location of heart valves?
Q3: When do the valves close and open?

Answer 3

Q1: Blood enters through the atria
Pulmonary vein brings oxygenated blood from lungs into left atrium
Vena cava brings deoxygenated blood from body tissues into right atrium
Goes into ventricles
Ventricles pump it out into arteries.
Artery from left side, that carries oxygenated blood to the body: aorta
Artery on right side, that carries deoxygenated blood to lungs: pulmonary artery
Q2: Blood is stopped from flowing backwards by four sets of valves.
Between right atrium and ventricle: tricuspid valve
Between left atrium and left ventricle: bicuspid valve
In the pulmonary artery and aorta: semilunar valves
They have tendons to prevent them from being turned inside out
Q3: When ventricles contract, bicuspid and tricuspid valves close (because of blood pressure in ventricles)
When ventricles relax, semilunar valves close (because of blood pressure in arteries)

Question 4

Circulatory System
Q1: What is the pathway of the two human circulations?
Q2: What are the blood vessels that carry blood to and from the heart called?
Q3: What is the pace-maker, how does it work?

Answer 4

Q1: - pulmonary circulation: heart to lungs and lungs to heart
- sytemic circulation: heart to body and body to heart
Q2: Oxygenated blood from lungs to heart: pulmonary vein
- Oxygenated blood from heart to body: aorta
- Deoxygenated blood from body to heart: Vena Cava
- Deoxygenated blood from heart to lungs: pulmonary artery
- Heart’s own supply of oxygen and nutrients: coronary arteries
Q3: - A small group of specialised muscle cells at the top of the right atrium, which initiate heartbeat.
- Supplied by two sets of nerves: one to speed up the heart, one to slow it down.
- These nerves originate in the centre of the brain, which receives an input from receptors.
- The receptors are sensitive to blood pressure, oxygen, carbon dioxide levels.

Question 5

Vessels
Q1: What are arteries, what is their structure and function?
Q2: Difference between small and big arteries? (location and structure)
Q3: What is a pulse?

Answer 5

Q1: - fairly wide vessles that carry blood away from the heart
- Have thick walls, elastic tissue and muscle fibres inside them
Q2: The nearer to the heart they are, the thicker they are, because pressure
- small arteries: have less elastic tissue and more muscle fibre than big ones (muscle fibres: contract and restrict blood flow to regulate it)
Q3: A pressure wave through the arteries

Question 6

Q4: Structure and function of capillaries?
Q5: How are materials transferred between capillaries and tissue fluid?
Q6: What is the structure and function of veins, how are they different from arteries?

Answer 6

Q4: A network of microscopic vessels passing between the cells of every living tissue. Thin, single-celled, permeable walls (allow some blood to leave them)
Q5: High pressure in the capillaries forces tissue fluid out. It contains nutrients and oxygen, and bathes all living cells. It takes up their waste products and oxygen, seeps back.
Q6: Thin walls, fibrous tissue, muscle layer. Blood pressure is lesser and more steady than arteries. Wider than arteries. Valves to prevent back flow.

Question 7

Q7: Vessels that carry blood to and from the liver?
Q8: Vessels that carry blood to and from the kidneys?
Q9: Vessels that carry blood to and from the brain?
Q10: Vessels that carry blood to and from the legs?
Q11: Vessels that carry blood to and from the head, neck and arms?

Answer 7

Q7: Hepatic artery and hepatic vein. (hepatic portal vein: intestine to liver)
Q8: Renal artery and renal vein.
Q9: Carotid artery, and jugular vein.
Q10: Femoral artery and femoral vein.
Q11: Subclavian artery and subclavian vein.

Question 8

Coronary heart disease
Q1: What is coronary heart disease, how is it caused (process)?
Q2: Causes of coronary heart disease?

Answer 8

Q1: Occlusion of arteries, caused by deposits of a fatty substance called atheroma in the arterial lining. Happens to everyone, but deposits get numerous with age. Patches join to form continuous layer, reducing internal diameter of arteries. Sometimes its surface becomes rough, causing plasma to deposit fibrin on it, forming a thrombus (blood clot). Blocks the artery.
Q2: 1. fatty diet: animals fats have high cholestrol. Atheroma deposits contain cholestrol.
2. stress Causes high blood pressure, which may increase the rate at which atheroma is formed
3. Smoking: Carbondioxide or other chemicals may damage arterial lining, causing atheroma to form
4. Lack of exercise: exercise improves blood flow, reducing risk.