topic 10 - human transport

Question 1

why do unicellular organisms rely on diffusion?

Answer 1

When the surface area to volume ratio is large, there is a lot of surface area for diffusion and not much volume to travel within. which is why unicellular organisms rely on diffusion alone to get the substances they need.

Question 2

why are transport systems needed in multicellular organisms?

Answer 2

multicellular organisms contain many layers of cells, meaning that the distance between the surface of the organism to its centre is relatively long. the diffusion distance is too great to rely on diffusion alone as it cannot occur at a sufficient rate to meet the needs of the organism, so larger organisms usually have transport systems, which is the circulatory system for humans.

Question 3

components of blood

Answer 3

red blood cells, white blood cells, platelets and plasma

Question 4

% of each component of blood

Answer 4

45% red blood cells, 55% plasma, less than 1% platelets and white blood cells.

Question 5

structure of red blood cell

Answer 5

• biconcave
• no nucleus
• plenty of protein haemoglobin

Question 6

structure of white blood cell

Answer 6

• large cell
• big nucleus
• all are slightly different

Question 7

structure of platelet

Answer 7

fragments of cells

Question 8

structure of plasma

Answer 8

straw coloured liquid

Question 9

role of plasma in transporting CO2

Answer 9

CO2 is dissolved in the plasma as hydrogencarbonate ions and transported from respiring cells to the lungs

Question 10

role of plasma in transporting digested food

Answer 10

the dissolved particles are absorbed from the small intestine and delivered to requiring cells around the body

Question 11

role of plasma in transporting urea

Answer 11

Urea is the waste substance produced in the breakdown of proteins by the liver. Urea is dissolved in the plasma and transported to the kidneys

Question 12

role of plasma in transporting hormones

Answer 12

hormones are released into the blood from the endocrine organs (glands) and delivered to target tissues/organs of the body

Question 13

role of plasma in transporting heat energy

Answer 13

heat energy is transferred to cooler parts of the body or to the skin where heat can be lost

Question 14

3 adaptations of red blood cells and how they help the transport of oxygen

Answer 14

• full of haemoglobin, a protein that binds to oxygen to form oxyhaemoglobin
• no nucleus which allows more space for haemoglobin to be packed in
• ‘biconcave disc, allowing them a large surface area to volume ratio to maximise diffusion of oxygen in and out

Question 15

2 types of white blood cells

Answer 15

phagocytes and lymphocytes

Question 16

function of phagocytes

Answer 16

• Phagocytes carry out phagocytosis by engulfing and digesting pathogens
• they are able to detect chemicals produced by pathogenic cells.
• Once they encounter the pathogenic cell, they will engulf it and release digestive enzymes to digest it, this is a non-specific immune response

Question 17

function of lymphocytes

Answer 17

• Lymphocytes produce antibodies.
• antibodies have a shape that is specific (complementary) to the antigens on the surface of the pathogen.
• this is a specific type of immune response as the antibodies produced will only fit one type of antigen on a pathogen

Question 18

what is it called when antibodies bind to antigens?

Answer 18

agglutination

Question 19

points to include in exam question: explain the bodies immune response to disease

Answer 19

• phagocytes that encounter the pathogen recognise that it is an invading pathogen and engulf and digest (non-specific response)
• eventually, the pathogen encounters a lymphocyte which recognises its antigens
• the lymphocyte starts to produce specific antibodies to combat that particular pathogen
• the lymphocyte clones itself to produce lots of lymphocytes (all producing the specific antibody required)
• antibodies cause agglutination of pathogens
• phagocytes engulf and digest the agglutinated pathogens
• memory cells can produce much larger quantities of the required antibody in a much shorter time to fight off the pathogen before the patient suffers any symptoms if they encounter the same pathogen.

Question 20

where are oxygenated and deoxygenated blood pumped in from and where do they go?

Answer 20

• oxygenated blood from the lungs enters the left side of the heart and is pumped to the rest of the body
• the left ventricle has a thicker muscle wall than the right ventricle as it has to pump blood at high pressure around the entire body
• deoxygenated blood from the body enters the right side of the heart and is pumped to the lungs
• the right ventricle is pumping blood at lower pressure to the lungs

Question 21

which ventricle is thicker and why?

Answer 21

the left ventricle has a thicker muscle wall than the right ventricle as it has to pump blood at high pressure around the entire body. the right ventricle is pumping blood at lower pressure to the lungs

Question 22

what separates the two sides of the heart

Answer 22

a muscle wall called the septum

Question 23

what are veins and arteries?

Answer 23

veins pump blood towards the heart and arteries pump blood out of the heart

Question 24

what are coronary arteries?

Answer 24

The coronary arteries supply the cardiac muscle tissue of the heart with oxygenated blood

Question 25

what are valves?

Answer 25

Valves are present to prevent blood flowing backwards

Question 26

structure of the heart (left and right)

Answer 26

RIGHT:
- pulmonary artery
- vena cava
- right atrium
- tricuspid valve
- right ventricle

LEFT:
- aorta
- pulmonary vein
- left atrium
- bicuspid valve
- left ventricle

semi-lunar valves are located on both sides of the heart below the pulmonary artery and aorta.

Question 27

pathway of blood through the heart (from vena cava to the rest of the body)

Answer 27

• deoxygenated blood coming from the body flows through the vena cava and into the right atrium
• the atrium contracts and the blood is forced through the tricuspid valve into the right ventricle
• the ventricle contracts and the blood is pushed through the semilunar valve into the pulmonary artery
• the blood travels to the lungs and moves through the capillaries past the alveoli where gas exchange takes place
• low pressure blood flow on this side of the heart prevents damage to the capillaries in the lungs
• oxygenated blood returns via the pulmonary vein to the left atrium
• the atrium contracts and forces the blood through the bicuspid valve into the left ventricle
• the ventricle contracts and the blood is forced through the semilunar valve and out through the aorta
• thicker muscle walls of the left ventricle produce a high enough pressure for the blood to travel around the whole body

Question 28

how does adrenaline affect the heart?

Answer 28

adrenaline increases heart rate, breathing rate and blood pressure to provide more oxygen and energy to the muscles.

Question 29

how does heart rate change during exercise?

Answer 29

Heart rate increases to deliver oxygen and glucose and remove waste more frequently. the volume of blood pumped out of the heart also increases to deliver bigger quantities of oxygen and glucose

Question 30

what is CHD?

Answer 30

coronary heart disease is the block up in coronary arteries by fatty deposits, caused by high cholesterol.

• If a coronary artery becomes partially or completely blocked by these fatty deposits, it loses its elasticity and cannot stretch to accommodate the blood which is being forced through every time the heart contracts.
• the flow of blood through the arteries is reduced, resulting in a lack of oxygen for the heart muscle, which could lead to heart attacks

Question 31

4 risks factors of CHD

Answer 31

• obesity - carrying extra weight puts a strain on the heart. 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

Question 32

3 types of blood vessels

Answer 32

• veins
• arteries
• capillaries

Question 33

5 key features of arteries

Answer 33

• carry blood at high pressure away from the heart
• carry oxygenated blood (except the pulmonary artery)
• have thick muscular walls containing elastic fibres - help withstand pressure
• have a narrow lumen - helps maintain high pressure
• blood flows through at a fast speed

Question 34

6 key features of veins

Answer 34

• carry blood at low pressure towards the heart
• carry deoxygenated blood (other than the pulmonary vein)
• have thin walls
• have a large lumen
• contain valves - prevent back flow of blood as it has low pressure
• blood flows through at a slow speed

Question 35

5 key features of capillaries

Answer 35

• carry blood at low pressure within tissues
• carry both oxygenated and deoxygenated blood
• have walls that are one cell thick - short diffusion distance for substances to pass through
• have ‘leaky’ walls - allows plasma to leak out
• speed of blood flow is slow

Question 36

structure of the circulatory system

Answer 36

RIGHT:
- pulmonary artery - takes blood to lungs

• vena cava - takes blood into the heart
• hepatic vein - takes blood from the liver to the heart
• hepatic portal vein - takes blood between the liver and gut
• renal vein - takes blood from the kidneys to the heart

LEFT:
- pulmonary vein - takes blood from the lungs to the heart

• aorta - takes blood out of the heart
• hepatic artery - takes blood from the heart to the liver
• mesenteric artery - takes blood from the heart to the gut
• renal artery - takes blood from the heart to the kidneys