mass transport in animals

Question 1

why is a mass transport system needed in larger organism

Answer 1

most cells are too far away from exchange surfaces for diffusion alone to maintain composition of tissue fluid within suitable metabolic range

mass transport maintains final diffusion gradients bringing substances to and from cells

helps maintain relatively stable immediate environment of cells that is tissue fluid

Question 2

draw the circulatory system

Answer 2

left side deoxygenated blood
kidneys to renal vein to vena cava entering heart to pulmonary artery from heart to lungs to be oxygenated

right side oxygenated blood
pulmonary vein from lungs to heart
aorta out of heart
renal artery to kidney

Question 3

why is the human a closed double circular system

Answer 3

prevents mixing of oxygenated and deoxygenated blood so blood pumped to body is fully saturated with oxygen so efficient delivery of oxygen and glucose for respiration

blood can be pumped at higher pressure so substances taken to and removed from body cells quicker and more efficiently

Question 4

describe the two circuits of the circulatory system

Answer 4

pulmonary circulation
- deoxygenated blood in right side of heart pumped to lungs
- oxygenated blood returns to left side

systematic circulation
- oxygenated blood in left side of heart pumped to tissues and organs
- deoxygenated blood returns to right side

Question 5

what is the purpose of the coronary arteries

Answer 5

deliver oxygenated blood to cardiac muscle

Question 6

describe the blood vessels entering and leaving lungs

Answer 6

aorta - takes oxygenated blood from heart to respiring tissues
vena cava - takes deoxygenated blood from respiring tissues to heart
pulmonary artery - takes deoxygenated blood from heart to lungs
pulmonary vein - takes oxygenated blood from lungs to heart

Question 7

describe the blood vessels entering and leaving kidneys

Answer 7

renal arteries - take oxygenated blood to kidneys
renal veins - take deoxygenated blood to vena cava from kidneys

Question 8

draw the human heart

Answer 8

right deoxygenated side
vena cava —> right atrium—> right ventricle —> pulmonary artery

left oxygenated side
pulmonary vein —> left atrium —> left ventricle —> aorta

semi lunar valves in pulmonary artery and aorta

atrioventricular valves in atriums

Question 9

how does the structure of the heart relate to its function

Answer 9

atrioventricular valves - prevent back flow of blood from ventricles to atria

semi lunar valves - prevent back flow of blood from arteries to ventricles

left has thicker muscular wall - generates higher blood pressure for oxygenated blood to travel greater distance around body

right has thinner muscular wall - generates lower blood pressure for deoxygenated blood to travel small distance to lungs higher pressure would damage alveoli

Question 10

describe the structure of the arteries and how it relates to its function

Answer 10

carry blood from heart to rest of body at high pressure

thick smooth muscle layer
- contact pushing blood along
- contain blood flow and pressure

elastic tissue layer
- stretch as ventricle contacts and recoil as ventricle relaxed
- reduces pressure surges and maintain high pressure

smooth and thin endothelium
- reduces friction

narrow lumen
- increases and maintains high blood pressure

Question 11

describe the structure of the arterioles and how it relates to it function

Answer 11

division of arteries to smaller vessels which can direct blood to different capillaries

similar to arteries but

tinker muscle layer
- constricts to reduce blood blood by narrowing linen
- dilates to increase blood flow by enlarging lumen

thinner elastic layers as lower pressure surges

Question 12

describe the structure of veins and how it relates to its function

Answer 12

carry blood back to heart under low pressure

wider linen than arteries

very little elastic and muscle tissue

valves
- prevent back flow

contraction of skeletal muscles squeezes veins maintaining blood flow

Question 13

describe the structure of capillaries and function

Answer 13

capillaries allow the efficient exchange of gases and nutrients between blood and tissue fluid

wall is thin layer for short diffusion path

capillary bed is made up of large network of beaches capillaries so increased surface area for diffusion

narrow lumen reducing flow rate so more time for exchange

no cell is far away from capillary short diffusion path

pores in walls between cells allows substances to escape

Question 14

what is tissue fluid

Answer 14

the fluid surrounding cells

provides respiring cells with water oxygen glucose amino acids

enables waste substance to move back into blood eg. urea carbon dioxide lactic acid

Question 15

describe the formation of tissue fluid

Answer 15

higher hydrostatic pressure inside capillaries than tissue fluid
forces fluid out of capillaries
large plasma proteins remain in capillaries

Question 16

describe the return of tissue fluid to circulatory system

Answer 16

hydrostatic pressure reduces as fluids leave capillaries
due to water loss an increasing conc. of plasma proteins lowers the water potential in capillary below tissue fluid
water re enters the capillaries by osmosis down water potential gradient
excess water taken up by lymph system and returned to circulatory system

Question 17

what may the causes of tissue fluid accumulation be

Answer 17

low conc. of protein in blood plasma

water potential in capillaries not as low so potential gradient reduced
more tissue fluid formed at arteriolar end
less water absorbed into capillary by osmosis

high blood pressure

high hydrostatic pressure
increased outward pressure at from arterial end reduces inward pressure at venal end
so more tissue fluid formed
lymph system not able to drain fast enough

Question 18

describe the pressure and volume changes associated with valve movement during the cardiac cycle

Answer 18

Atrial systole
- Atria contract→decreasing volume and increasing pressure inside atria
- Atrioventricular valves forced open
- When pressure inside atria > pressure inside ventricles, atrioventricular valves open
- Blood pushed into ventricles
- (note: semilunar valves are shut)

Ventricular systole
- Ventricles contract from the bottom up → decreasing volume and increasing pressure inside ventricles
- Semilunar valves forced open
- When pressure inside ventricles > pressure inside arteries
- Atrioventricular valves shut
- When pressure inside ventricles > pressure inside atria
- Blood pushed out of heart through arteries

Diastole
- Atria and ventricles relax→increasing volume and decreasing pressure inside chambers
- Blood from veins fills atria (increasing pressure inside atria slightly) and flows passively to
ventricles
- Atrioventricular valves open
- When pressure inside atria > pressure inside ventricles blood flows passively to ventricles

Semilunar valves shut
- When pressure inside arteries > pressure inside ventricles
- Note: the purpose of valves shutting is to prevent back flow into (named chamber / vein) to maintain unidirectional flow of blood through the heart

Question 19

how to work out cardiac output and what is it

Answer 19

stoke volume x heart rate

cardiac output - amount of blood pumped out the heart per minute
stroke volume - volume of blood pumped by ventricles in each heart beat
heart rate - number of beats per min

Question 20

how to calculate heart rate from cardiac cycle

Answer 20

one beat = one cardiacs cycle
find the length of one cardiac cycle
heart rate per min = 60/ length of one cardiac cycle in second s

Question 21

when are the semilunar valves closed

Answer 21

when pressure in aorta/ pulmonary artery is higher than ventricle —> prevents backflips of blood from arteries to ventricles

Question 22

when are semilunar valves open

Answer 22

when pressure in ventricles is higher than in aorta/pulmonary artery -> blood flows from ventricle to aorta

Question 23

when are atrioventricular valve closed

Answer 23

when pressure in atrium is higher than ventricles —> prevents back flow of blood from ventricle to aorta

Question 24

when are atrioventricular valves open

Answer 24

when pressure higher in ventricle than atrium —> blood flows from ventricle to atrium

Question 25

what is coronary heart disease and what are the risk factors

Answer 25

often associated with atherosclerosis and atheroma formation

atheroma causes narrowing of coronary arteries restricting blood flow to heart
heart anaerobically respires -> less ATP —> not enough energy to contract—> lactate produced —> tissue damage

risks
- age
- diet high in salt or saturated fats
- high alcohol consumption
- stress
- smoking
- genes

Question 26

how to analyse and interpret data associated with specific risk factors and the incidence of cardiovascular disease

Answer 26

data interpretation
- overall tend : positive negative or linear
- most obvious trend
- manipulate data - difference from two points, how may time greater, percentage change

Question 27

how would you evaluate conflicting evidence associated with risk factors affecting cardiovascular disease

Answer 27

sample size
other risk factors
used similar groups eg. age gender
way in which info collected

Question 28

how are red blood cells adapted

Answer 28

no nucleus - more space for haemoglobin
biconcave shape - increased surface area to volume ration for short diffusion distance

Question 29

what is the role of haemoglobin

Answer 29

associates with oxygen near exchange surfaces where partial pressure of oxygen high
forming oxyhemoglobin which transports oxygen
dissociates near cells where partial pressure is low

Question 30

what is the structure of haemoglobin

Answer 30

protein quaternary structure

made of 4 polypeptide chains
each contains a Haem group containing an iron ion

Question 31

how is oxygen loaded transported and unloaded in regions with low partial pressure of oxygen

Answer 31

respiring tissues

low affinity for oxygen
so unloads readily with Hb
so % saturation is low

Question 32

how is oxygen loaded transported and unloaded in regions with high partial pressure of oxygen

Answer 32

gas exchange surfaces

Hb has high affinity for oxygen
so readily loads with Hb
so % saturation high

Question 33

draw an oxygen dissociation curve and explain

Answer 33

show how saturation is haemoglobin with oxygen changes as partial pressure of oxygen changes

at low partial pressure as oxygen increases there is a slow increase in % saturation when first oxygen is binding

at higher partial pressure of oxygen as oxygen increases there is a rapid increase in % saturation as it is easier for oxygens to bind

s shaped curve

Question 34

what is the Bohr effect

Answer 34

effects of CO2 on dissociation if oxyhemoglobin

shift to the right

increasing blood CO2 dues to increased respiration
lowers blood pH
reducing Hbs affinity for oxygen as tertiary structure changes
so more unloading of oxygen to respiring tissues

curve shifts right due to increased carbon dioxide

Question 35

what happens if the oxygen dissociation curve shifts right

Answer 35

Hb has lower affinity for oxygen

more oxygen dissociates
at respiring tissues
eg. organisms with high rates of respiration

Question 36

what happens if the oxygen dissociation curve shifts left

Answer 36

Hb has higher affinity for oxygen

more oxygen associated
at gas exchange surfaces where pO2 li lower
eg. organisms in low oxygen environments