3.1.2 Transport in animals

Question 1

What is the need for transport systems in multicellular organisms?

Answer 1

smaller SA: V ration;
higher metabolic rate;
takes longer for oxygen to diffuse into organism;
prevent waste product building up;
longer diffusion distance;

Question 2

What is a double circulatory system?

Answer 2

blood passes to the heart twicer per circuit of the body

systemic circulation
pulmonary circulation

Question 3

What is an advantage of a double circulatory system?

Answer 3

pulmonary circulation = can be under a lower pressure = doesn’t damage lungs

systemic circulation = under higher pressure = allows blood to be pumped around the whole body speed of circulation

Question 4

What is a closed circulatory system?

Answer 4

blood is enclosed in blood vessels at all times

Question 5

What is the circulatory system in fish?

Answer 5

single closed

Question 6

What is the circulatory system in insects?

Answer 6

open circulatory

Question 7

What is an open circulatory system?

Answer 7

blood is not enclosed in blood vessels at all times

tissues and cells are in direct contact of blood

Question 8

What is a single circulatory system?

Answer 8

blood passes through the heart once each circuit of the body

Question 9

What is the general structure of blood vessels?

Answer 9

tunica externa = collagen
tunica media = smooth muscle + elastic tissue
tunica intima = squamous epithelial + endothelium

Question 10

What is the structure of an artery?

Answer 10

narrow lumen
thick tunica media
(elastic tissue to maintain pressure by stretching and recoiling and smooth muscle contracts to constrict blood vessel)

Question 11

What is the difference between a artery and a ateriole?

Answer 11

thicker smooth muscle
vasodilation and vasoconstriction
widen/narrow lumen
blood flow into capillaries controlled

elastic fibre is thinner

Question 12

What is the structure of capillaries?

Answer 12

one cell thick - short diffusion distance
squamous epithelial cells
smooth - prevent friction
fenestrations = allow substances to move into and out of the cell = tissue fluid formation
lots of them = large SA

Question 13

What is the structure of a vein?

Answer 13

large lumen = blood under low pressure
thin tunica media
valves prevent backflow
collagen = strength

Question 14

How is tissue fluid formed?

Answer 14

1) blood flows from the arteriole end at a higher hydrostatic pressure than oncotic pressure

2) the high pressure forces fluid out through the fenestrations in the capillary walls where oxygen and nutrients dissolve into it

3) the fluid with the dissolved oxygen and nutrients seeps into the cells

Question 15

How does tissue fluid return too the blood?

Answer 15

1) large proteins and red blood cells remain in the capillaries lowering the water potential

2) the oncotic pressure is higher than the hydrostatic pressure at the venous end

3) the water moves back into the blood from the fluid by osmosis down conc gradient

Question 16

What is the composition of blood tissue fluid and the lymph?

Answer 16

see on iPad

Question 17

What happens to 10% of tissue fluid?

Answer 17

enters the lymph vessel

Question 18

What component does tissue fluid only have a few of?

Answer 18

white blood cells

Question 19

What component does the lymph only have a few of?

Answer 19

glucose

Question 20

Whats the difference between blood plasma and tissue fluid?

Answer 20

tissue fluid doesnt contain plasma proteins because theyre too large to pass through the fenestrations in the capillary wall

Question 21

Draw the heart:

Answer 21

iPad

Question 22

What is found on the external side of heart?

Answer 22

coronary arteries = supplies blood to the heart

needs glucose and oxygen for respirations = contract to pump blood

Question 23

What are the three stages of the cardiac cycle?

Answer 23

diastole
atrial systole
ventricular systole

Question 24

What occurs during cardiac systole?

Answer 24

the heart is relaxed;
blood enters through the pulmonary vein and the vena cava into the atrium;
higher pressure in the vena cava and vein than the atrium and ventricle;
blood flows down the pressure gradient into atrium;
AV valves are open as pressure in atria increase

Question 25

What occurs during atrial systole?

Answer 25

atria contract;
pressure increases causing the atria to empty out and blood moves into ventricles;
via the AV valves;
pressure in ventricles slightly increase;
AV close to prevent backflow of blood

Question 26

What occurs during ventricular systole?

Answer 26

ventricles contract;
pressure further increases and has a higher pressure than the arteries;
semi lunar valves open;
blood flows down pressure gradients from ventricles to arteries

Question 27

How do you work out cardiac output?

Answer 27

heart rate x stroke volume

Question 28

How is the heart action initiated and coordinated?

Answer 28

1) SAN sends nerve impulse through the atria = atria contract simultaneously (atrial systole)

2) nerve impulse from SAN spread to the ventricles to the AVN - AVN delays impulse to allows atrial empty out and contract after the atria

3) impulse goes down bundle of His to the apex and purkyne fibres causing ventricles to contract - ventricular systole

Question 29

Why is the heart called myogenic?

Answer 29

initiates and coordinates its own contraction without needed to be connected to nervous system

Question 30

What is the role of the SAN?

Answer 30

sinoatrial node;
natural pace maker;
ensures heart is beating at a constant rate;

Question 31

How is the heart action initiated and coordinated? (markscheme)

Answer 31

SAN initiates excitation;
wave of excitation spreads over atrial wall;
atria contract;
contraction is synchronised;
reaches AVN;
delay at AVN;
excitation spreads to septum;
bundle of His/purkyne fibres;
ventricles contract from apex

Question 32

What is tachychardia?

Answer 32

fast heart rate

Question 33

What is bradychardia

Answer 33

slow heart rate

Question 34

What is fibirilation?

Answer 34

irregular heart beat

Question 35

What is a ectopic heart rate?

Answer 35

heart skips a beat

Question 36

What is the role of haemoglobin?

Answer 36

binds to oxygen in the lungs to form oxyhaemoglobin and then dissociates into tissues as oxygen and haemoglobin = oxygen used in aerobic respiration

Question 37

How are hydrogencarbonate ions formed?

Answer 37

carbon dioxide diffuses into the blood;
carbon dioxide binds with water to make carbonic acid;
catalysed by carbonic anhydrase;
carbonic acid dissocated forming hydrogen ions and hydrogen carbonate ions;
chloride ions move into the RBC to maintain charge ;
Hydrogen ions are taken up by the Hb = acts as buffer forming haemoglubinic acid

Question 38

What is the Bohr effect?

Answer 38

oxygen dissociation curve moves to the right at high conc of carbon dioxide

Question 39

What occurs at high conc of carbon dioxide?

Answer 39

shape of Hb is altered;
Hb affinity for oxygen is reduced;
more dissociation of oxyhaemoglobin therefore more oxygen available for respiring tissues;
Hb acts as a buffer;
by bindning to the hydrogen ions;
forming hamoglobinic acid;
Hb binds to carbon dioxide to form carbaminohaemoglobin