II: 7.2 - Transport in humans

Question 1

What is the circulatory system?

Answer 1

A system of tubes (veins, capillaries, arteries) with a pump (heart) and valves (in heart and veins) to ensure one-way flow of blood.

We need a transport system to deliver oxygen, nutrients and other substances to all our body cells, and take away waste products from them.

Question 2

Describe the double circulation of blood

Answer 2

Systemic:

• High pressure circulation transporting oxygenated blood to the body tissues and deoxygenated blood from them
• Longer distance, so stronger circulation and higher pressure needed

Pulmonary:

• Low pressure circulation transporting deoxygenated blood to the lungs and oxygenated blood from the lungs
• Shorter distance, so weaker circulation and lower pressure needed

Question 3

State the name and function of A

Answer 3

Superior vena cava

Carries in deoxygenated blood from the upper body

Question 4

State the name and function of B

Answer 4

Pulmonary vein

Carries oxygenated blood from the lungs to the left atrium

Question 5

State the name and function of C

Answer 5

Right atrium

Receives deoxygenated blood from the body via the vena cava

Question 6

State the name and function of D

Answer 6

Pulmonary semi-lunar valve

Prevents a backflow of blood between the right ventricle and pulmonary artery

Question 7

State the name and function of E

Answer 7

Tricuspid valve

Prevents a backflow of blood between the right atrium and right ventricle

Remember: tricuspid valve on the right side

Question 8

State the name and function of F

Answer 8

Inferior vena cava

Carries in deoxygenated blood from the lower body

Question 9

State the name and function of G

Answer 9

Aorta

Carries out oxygenated blood from the left ventricle to the rest of the body

Question 10

State the name and function of H

Answer 10

Pulmonary artery

Carries deoxygenated blood from the right ventricle to the lungs

Question 11

State the name and function of I

Answer 11

Left atrium

Receives oxygenated blood from the lungs via the pulmonary vein

Question 12

State the name and function of J

Answer 12

Bicuspid valve

Prevents a backflow of blood between the left atrium and left ventricle

Question 13

State the name and function of K

Answer 13

Aortic semi-lunar valve

Prevents a backflow of blood from the aorta to the left ventricle

Question 14

State the name and function of L

Answer 14

Left ventricle

Pumps oxygenated blood to the body tissues via the aorta

Has a thick muscular wall as high pressure is needed to reach the whole body

Question 15

State the name and function of M

Answer 15

Septum

Separates the two sides of the heart

Question 16

Describe the steps of the cardiac cycle

Answer 16

1. Atrial systole: artia contract and push blood into the ventricles
2. Ventricular systole: ventricles contract and puch blood into the arteries; bicuspid and tricuspid valves close
3. General/cardiac diastole: all chambers relax, allowing blood to seep in; semi-lunar valves close

Question 17

State and explain the effect of physical activity on pulse rate

Answer 17

Increased physical activity usually leads to an increased pulse rate.

This is because physical activity makes the heart beat more quickly and more deeply, for an increased circulation of blood so that more oxygen and glucose can get to the muscles.

Fitter people’s pulse rate returns to normal faster after physical activity as their hearts can pump blood more effectively.

Question 18

Describe coronary heart disease and list the symptoms

Answer 18

• The coronary arteries bring blood and oxygen to the heart. Fatty material and other substances form a plaque build-up on the walls of the coronary arteries. This may also be called hardening of the arteries.
• This build-up causes the arteries to get narrow.
• As a result, blood flow to the heart can slow down or stop
• The heart muscle cells are deprived of oxygen and glucose, and poisonous wastes such as lactic acid build up
• Part of the heart muscle stops contracting, causing a heart attack
• Symptoms:
  
  • Chest pain or discomfort (also known as angina)
  • Shortness of breath and fatigue with activity (exertion)

Question 19

State the possible causes and preventive measures of coronary heart disease

Answer 19

Causes:

• diet
• stress
• smoking
• alcohol

Preventative measures:

• have a healthy, balanced diet
• exercise at least 30 minutes a day
• don’t smoke
• avoid excessive consumption of alcohol
• learn healthy ways to cope with stress through special classes or programs, or things like meditation or yoga

Question 20

Name the main blood vessels to and from the heart, lungs, liver and kidney

Answer 20

Lungs→heart = Pulmonary vein
Liver→heart = Hepatic vein
Kidneys→heart = Renal vein

Heart→lungs = Pulmonary artery
Heart→liver = Hepatic artery
Heart→kidneys = Renal artery

Question 21

Describe the function and structure of arteries

Answer 21

• carry (oxygenated) blood away from the heart
• small lumen to maintain high pressure
• thick muscle layer to withstand high pressure
• elastic fibres help to pulse blood
• high pressure prevents backflow of blood

Question 22

Describe the function and structure of veins

Answer 22

• carry (deoxygenated) blood to the heart
• large lumen reduces resistance to blood flow
• thinner layer of muscle and elastic fibres as they do not need to withstand high pressure
• have valves to prevent a backflow of blood
• in the legs, the muscles squeeze blood up against gravity

Question 23

Describe the function and structure of capillaries

Answer 23

• takes oxygenated blood from arteries to cells, and deoxygenated blood from cells to veins
• walls are only one cell thick
• often as little as 0.001mm in diameter
• thin walls allow liquid to pass through, i.e. they are permeable

Question 24

Describe the transfer of materials between capillaries and tissue fluid

Answer 24

• tissue fluid diffuses out of the capillaries, containing nutrients and oxygen
• the slow flow rate in the capillaries allows plenty of time for the exchange of O₂, CO₂, nutrients and waste
• some tissue fluid, now containing waste products, is absorbed back into the capillaries, some enters lymphatic vessels
• fluid in lymphatic vessels (lymph) eventually empties back into the blood

Question 25

List the four components of blood

Answer 25

1. Red blood cells 2. White blood cells 3. Plasma 4. Platelets

Question 26

Identify this component of blood and state its functions and adaptations

Answer 26

**Red blood cell** * oxygen transport * life span - about 120 days * no nucleus, so more capacity for oxygen * contain haemoglobin - a red pigment/protein combined with iron * bi-concave shape to increase surface area * flexible so that they can squeeze through narrow blood vessels * thin cell membranes to let oxygen diffuse through quickly Oxygen is carried as *oxyhaemoglobin*, an unstable product formed from oxygen and haemoglobin that breaks down in places of low oxygen concentration.

Question 27

Identify the following component of blood and state its function and adaptations

Answer 27

**Lymphocyte** * defense against disease - antibody formation * very large nucleus holds instructions to produce many different antibodies

Question 28

Describe how antibodies in the immune system help to defend against disease

Answer 28

* antibodies - proteins which attack pathogens by: * attaching to the surface of the pathogen and make it easier for phagocytes to ingest it * clumping the bacteria together * neutralising the toxins produced by the pathogen * locking onto it and destroying it * antibodies are specific, i.e. each type will only attack a certain pathogen * lymphocytes produce antibodies when a pathogen has been detected by its antigens - chemicals on the surface of the cells ## Footnote Tissue rejection happens as a result of white blood cells not recognising the antigens on the tissue as belonging to oneself, and attempt to destroy it.

Question 29

Identify the following component of blood, and state its functions and adaptations

Answer 29

**Phagocyte** * defense against disease - engulfs and destroys pathogens (phagocytosis) * life span - about 20 days * lobed nucleus allow it to change shape and squeeze through small spaces * has vesicles containing digestive enzymes to digest/destroy pathogens

Question 30

Describe phagocytosis

Answer 30

1. Pathogen is detected/identified 2. False feet formed to surround pathogen 3. Pathogen engulfed with water droplet 4. Digestive enzymes digest pathogen 5. Toxins released from pathogen, killing the phagocyte

Question 31

Identify the following component of blood and state its function

Answer 31

**Platelets** * fragments of red blood cells * causes clotting (helps heal wounds) * produces clotting factor

Question 32

Describe the process of clotting

Answer 32

* person gets wounded * platelets produce clotting factor * clotting factor converts fibrinogen (soluble) to fibrin (insoluble) * platelets, red blood cells and white blood cells get trapped in fibrin network/mesh, forming a clot * this eventually dries to form a scab ## Footnote Calcium is needed for this process

Question 33

State the function of blood plasma

Answer 33

Transport of blood cells, ions, soluble nutrients, hormones, carbon dioxide, urea and plasma proteins ## Footnote (also a little dissolved oxygen, only about 1% of oxygen is carried in plasma)

Question 34

Describe the function of the lymphatic system

Answer 34

* Circulation of body fluids, and the production of lymphocytes * Lymph node contains many lymphocytes which filter lymph * Tissue fluid: made when plasma is squeezed out of capillaries * Substances diffuse between cells and tissue fluid * Some tissue fluid returns to the capillaries by osmosis * Lymph vessels collect excess tissue fluid (now called lymph), have valves to prevent backflow * Lymph vessels from all parts ot the body join up to make two thoracic ducts * Ducts join with subclavian veins, blood flows to heart