transport in humans

Question 1

why do simple, unicellular organisms not need independent transport systems?

Answer 1

unicellular organisms have a large surface area in comparison to their volume –> this means a short distance across the organism.
they therefore dont need specialist exchange surfaces or transport systems bc they can rely on diffusion, osmosis and active transport.

Question 2

why do multicellular organisms need transport systems?

Answer 2

multicellular organisms have lots of cells and therefore a higher volume in comparison with their surface area.

With a small surface area to volume ratio, multicellular organisms therefore have inefficient rate of diffusion, preventing cell to rely on diffusion to transport necessary substances in and out of the cell and therefore a transport system is required.

Question 3

what artery takes oxygenated blood from the heart?

Answer 3

aorta

Question 4

what artery/vein takes oxygenated blood to the liver?

Answer 4

hepatic artery

Question 5

what artery/vein takes oxygenated blood to the gut?

Answer 5

mesenteric artery

Question 6

what artery/vein takes oxygenated blood to the kidneys?

Answer 6

renal artery

Question 7

what artery/vein takes deoxygenated blood from the liver?

Answer 7

hepatic vein

Question 8

what artery/vein takes deoxygenated blood from the gut (via which other organ)

Answer 8

deoxygenated blood from the gut goes to the liver via the hepatic portal vein

Question 9

what artery/vein takes deoxygenated blood from the kidneys?

Answer 9

renal vein

Question 10

what are the roles of the pulmonary artery and pulmonary vein and what makes them unique?

Answer 10

pulmonary artery - carries DEOXYGENATED blood from the heart to the lungs

pulmonary vein - carried OXYGENATED blood from the lungs to the heart

they are different because usually an artery carries oxygenated blood away from the heart and a vein does the opposite. the pulmonary artery and pulmonary vein act in contradiction with most arteries/veins

Question 11

how are arteries structured and why?

Answer 11

• thick elastic walls
• small lumen
• Thick muscular walls to withstand high pressure from the heart pumping out freshly oxygenated blood
• Narrow lumen to maintain high pressure to pump blood around the body

Question 12

how are veins structured and why?

Answer 12

• thin wall
• large lumen
• valve
• Thin walls to allow Skeletal muscle to exert pressure on Vein
• Wide lumen to transport large volume of blood
• Valves to prevent the backflow of blood under low pressure

Question 13

how are the capillaries structured and why?

Answer 13

• thin cell wall
• porous membrane
• branched
• Thin walls (one cell thick) that are porous and permeable for efficient material exchange via diffusion
• Narrow lumen to fit between cells for extensive branching, which increases surface area to volume ratio for efficient material exchange via diffusion

Question 14

what is the heart?

Answer 14

it is a chambered muscle organ that is composed of Cardiac muscle, and is myogenic to initiate contractions to pump blood around the body

Question 14

what factors may increase the risk of developing coronary heart disease?

Answer 14

cardiac muscle cells need a supply of blood to deliver oxygen and glucose and to remove waste products such as carbon dioxide

In coronary heart disease (CHD), layers of fatty material (plaque) build up inside the coronary arteries

factors:
- Obesity
Increased weight can lead to Type 2 diabetes which further damages your blood vessels

• High blood pressure
  This increases the force of the blood against the artery walls and consequently leads to damage of the vessels
• High cholesterol
  Speeds up the build up of fatty plaques in the arteries leading to blockages
• Smoking
  Chemicals in smoke cause an increase in plaque build up and an increase in blood pressure
• Carbon monoxide also reduces the oxygen carrying capacity of the red blood cells

Question 14

how does the heart function?

Answer 14

• Deoxygenated blood from respiring cells are carried by the Vena Cava to the Right Atrium
• Right Atrium will contract to increase pressure, pushing blood into Right Ventricle through tricuspid valve
• Tricuspid valve closes to prevent backflow of blood from Ventricle to Atrium
• Right Ventricle will contract to increase pressure, causing blood to be carried out via Pulmonary Artery to be Oxygenated at the Lungs through the Semilunar Valve
• Semilunar Valve closes to prevent backflow of blood from Artery to Ventricle
• Pulmonary Vein carries Oxygenated blood from Lungs to the Left Atrium
• Left Atrium will contract to increase pressure, pushing blood into Left Ventricle through Semilunar Valve
• Semilunar Valve closes to prevent backflow of blood from Ventricle to Atrium
• Left Ventricle will contract to increase pressure, causing Oxygenated blood to be carried out via Aorta to respiring cells around the body

Question 15

what artery/vein carries deoxygenated blood into the heart?

Answer 15

vena cava

Question 16

how does the heart rate change during exercise?

Answer 16

During exercise, more energy is needed via respiration to allow muscle contractions to occur to facilitate movement

Hence, heart rate will increase to allow more oxygen transport in blood to respiring cells for movement to occur

If energy demand exceeds oxygen intake, energy may be produced via anaerobic respiration, producing Lactic acid as a waste product

After exercise, heart rate continues to increase as extra Oxygen is needed to break down the Lactic acid produced - Oxygen debt

Question 17

how does heart rate change under the influence of adrenaline?

Answer 17

During times of fear or stress, adrenaline is produced by adrenal glands and secreted into the bloodstream

As a result, liver cells convert glycogen into glucose to increase blood glucose levels

Additionally, breathing and heart rate increases to increase blood flow

Hence, the increase in breathing and heart rate allows more glucose and
oxygen to be transported in the bloodstream to respiring cells for ‘fight or flight’ response to occur

Question 18

what is a red blood cell?

Answer 18

Transports oxygen in haemoglobin of cell from lungs to respiring cells for aerobic respiration. they have a biconcave structure and no nucleus to allow it to better fulfil its function.

Question 19

what is a white blood cell?

Answer 19

Composed of two types of cells - phagocytes that engulf and digest pathogens, and lymphocytes that produce antibodies to deactivate antigens of bacteria

Question 20

what is a platelet?

Answer 20

Cell fragments involved in blood clotting which prevents blood loss and the entry of micro-organisms

Question 21

what is plasma?

Answer 21

Medium of transport that carries carbon dioxide, digested food, urea, hormones and heat

Question 22

how does the immune system respond to disease?

Answer 22

the immune system has two types of white blood cell: phagocytes and lymphocytes. lymphocytes produce antibodies which disable specific antigens of different pathogens. once disabled the pathogen is then engulfed/consumed by the phagocyte and destroyed.

Question 23

how does vaccination help protect against pathogens?

Answer 23

vaccinations are either weakened or dead versions of a pathogen which have the same antigens but are not harmful. your body identifies the pathogen as foreign and starts producing the suitable antibodies. once the antibodies have been produced once, the white blood cells become memory cells which can then produce the suitable antibodies more quickly and in a greater quantity when the same pathogen (but harmful) enters the body and destroying it before any harm is caused. therefore, allowing one to be immune.