Chapter Eight: Transport In Animals

Question 1

what transport system do multicellular animals use? why do multicellular animals need a transport system?

Answer 1

• the circulatory system
• hard to supply multicellular animal cells with everything they need since they are relatively big, causing them to have a low SA:VOL ratio and a higher metabolic rate

Question 2

what are the four types of circulatory systems? give examples of what organisms have which circulatory systems.

Answer 2

• open: some invertebrates (like insects)
• closed: fish and mammals (vertebrates)
• single: fish
• double: mammals

Question 3

describe single and double circulatory systems.

Answer 3

single circulatory system:
- blood only passes through the heart once for each complete circuit around the body
- fish: heart pumps blood to the gills and then through the rest of the body in a single circuit

double circulatory system:
- blood passes through heart twice for each complete circuit around the body
- mammals: heart divided down the middle.
1. right side of the heart pumps blood to the lungs
2. lungs pump blood to left side of the heart which is then pumped to the rest of the body
3. when blood returns to heart, it enters the right side again

Question 4

describe open and closed circulatory systems.

Answer 4

closed circulatory system:
- blood enclosed in blood vessels
1. heart pumps blood into arteries that branch out into many capillaries
2. substances like oxygen and glucose from the blood into body cells but blood stays in vessels
3. veins take blood back to heart

open circulatory system:
- blood isn’t enclosed, instead flows freely through body cavity
1. heart is segmented, contracts in a wave, starting from the back, pumping blood into a single main artery
2. artery opens up into body cavity
3. blood flows around insects organs, then makes its way back to the heart segments through a series of valves
- doesn’t supply cells with oxygen

Question 5

what is the structure and function of arteries and arterioles?

Answer 5

arteries:
- carry blood from the heart to the rest of the body features:
- thick muscular walls that have elastic tissue helping to maintain the high pressure as the heart beats
- folded endothelium (inner lining) which allows artery to expand and maintain high pressure

arterioles:
- branch from arteries
- layer of smooth muscle, less elastic tissue
- smooth muscle allows them to expand and contract, controlling amount of blood flowing to tissues

Question 6

what is the structure and function of capillaries?

Answer 6

• arterioles branch into capillaries
• one cell thick providing a short diffusion distance for exchanging substances between the blood and cells

Question 7

what is the structure and function of venules and veins?

Answer 7

venules:
- connected to capillaries
- thin walls that contain some muscle cells
- join together to form veins

veins:
- take blood back to heart under low pressure
- wider lumen than arteries with very little elastic or muscle tissue
- contain valves to stop back flow of blood
- blood flow helped by contraction of body muscles surrounding them
(all carry deoxygenated blood except pulmonary veins that carrv blood from lungs to heart )

Question 8

describe hydrostatic and oncotic pressure. what are they responsible for?

Answer 8

• hydrostatic pressure is the pressure exerted by liquid
• oncotic pressure is the tendency of water to move into the blood via osmosis
• the interaction of the pressures are responsible for for the formation and reabsorption of tissue fluid

Question 9

describe tissue fluid formation.

Answer 9

• as blood enters the capillaries from the arterioles the hydrostatic (liquid) pressure in the capillaries is greater than the hydrostatic pressure in the tissue fluid. the difference in pressure forces fluid out of the capillaries and into the spaces around the cells forming tissue fluid

• as fluid leaves the hydrostatic pressure reduces in capillaries, so hydrostatic pressure is much lower at the end of the capillary bed that’s nearest to the venules

Question 10

describe tissue fluid reabsorption.

Answer 10

• large molecules remain in capillaries, lowering water potential of blood remaining in capillary
• lowered water potential = higher oncotic pressure
• venule end of capillaries: hydrostatic pressure low due to loss of liquid, but water potential is very low. this all results in the net movement of liquid is back into the capillary by osmosis
• once equilibrium of the water potential of the blood is reached, no more water from the tissue fluid can be reabsorbed back into the capillaries.

Question 11

what happens to the excess tissue fluid during tissue fluid reabsorption?

Answer 11

• absorbed into the lymphatic system and eventually into the bloodstream near the heart
• liquid in the lymphatic system is called lymph

Question 12

describe lymph.

Answer 12

• similar make up as plasma, however is doesn’t contain the large plasma proteins and is has less oxygen and nutrients (would have been absorbed by the cells)

Question 13

what are the differences between blood, tissue fluid, and lymph?

Answer 13

red blood cells:
- only in blood. too big to get through capillary walls into tissue fluid

white blood cells:
- in blood and lymph, very few in tissue fluid. most found in lymph system. only enter tissue fluid when there’s an infection

platelets:
- only in blood, only in tissue fluid if capillaries are damaged

proteins:
- in blood, very few in tissue fluid, only antibodies in lymph. most plasma proteins too large to fit through capillary walls.

water:
- in all, tissue fluid and lymph have a higher water potential than blood

dissolved solutes:
- in all, they can move freely between blood, tissue fluid, and lymph.

Question 14

list all the parts of the external structure of the heart. label a diagram to make sure you know where each part is.

Answer 14

• pulmonary artery
• left atrium
• pulmonary veins
• left ventricle
• inferior vena cava
• right ventricle
• coronary artery
• right atrium
• aorta
• superior vena cava

Question 15

list all the parts of the internal structure of the heart. label a diagram to make sure you know where each part is.

Answer 15

left side:
- pulmonary veins
- left atrium
- atrioventricular valve
- cords/valve tendons
- left ventricle
- semi-lunar valve
- aorta

right side:
- superior and inferior vena cava
- right atrium
- atrioventricular valve
- right ventricle
- semi-lunar valve
- pulmonary artery

Question 16

describe these features of the heart: cardiac muscle, coronary arteries, pericardial membranes

Answer 16

• cardiac muscle is myogenic, it can contract and relax without receiving signals from nerves
• coronary arteries supply the cardiac muscle with oxygenated blood for aerobic respiration which provides ATP so the cardiac muscle can continually contract ad relax
• pericardial muscles surrounds the heart. they are inelastic membranes that prevent the heart from filling and swelling with blood

Question 17

describe the role and features of the left ventricle.

Answer 17

• thick muscular wall so it can contract with more force and pump blood at a higher pressure which is needed so blood will flow all the way around the body

Question 18

describe the role and features of the right ventricle.

Answer 18

• only pumps blood to the lungs, requires blood flow to move slowly to allow time for gas exchange
• muscular wall is much thinner since blood dosent need to be pumped at as high a pressure

Question 19

describe the role and features of the atria.

Answer 19

• pumps blood from the atria into the ventricles, minimal force and pressure required
• has thin muscular walls due to its job role

Question 20

what is the role and features of valves in the heart? how do they work

Answer 20

• prevent blood rom flowing the wrong way
• atrioventricular valves connect atria to ventricles, semi-lunar valves connect ventricles to the pulmonary artery and the aorta
• work by only allowing blood to flow one way , they are open or closed depending on the relative pressure of the heart chambers
• high pressure behind valve = forced open
• high pressure in front of valve = forced shut

Question 21

what are the three stages of the cardiac cycle?

Answer 21

1. diastole
2. atrial systole
3. ventricular systole

Question 22

what happens during diastole?

Answer 22

• ventricles and atria relax, higher pressure in pulmonary artery and aorta causes semi-lunar valves to close
• atria fills with blood due to high pressure in vena cava and pulmonary vein
• ventricle pressure falls below pressure in the atria, causing atrioventricular valves to open and blood flows passively into ventricles

Question 23

what happens during atrial systole?

Answer 23

• ventricles are relaxed, atria contract which decreases their volume and increases their pressure, pushing blood into ventricles through atrioventricular valves
• slight increase in ventricular pressure and volume as they are receiving the ejected blood from the contracting atria

Question 24

what happens during ventricular systole?

Answer 24

• atria relaxes, ventricles contract which causes a decrease in volume and an increase in pressure
• pressure higher in ventricles than atria, forcing atrioventricular valves to shut preventing backflow
• high pressure in ventricles causes semi-lunar valves to open, forcing blood out into the pulmonary artery and aorta

Question 25

what is cardiac output? how do you calculate it?

Answer 25

- the volume of blood which leaves one ventricle in one minute cardiac output = heart rate x stroke volume heart rate = beats of the heart per minute (min^-1) stroke volume = volume of blood that leaves the heart each beat (dm^3)

Question 26

what elements control the cardiac cycle?

Answer 26

- sino-atrial node - atrio-ventricular node - purkyne tissue - bundle of His

Question 27

describe the elements that make up the cardiac cycle.

Answer 27

- sinoatrial node (SAN): in wall of right atrium, sets the rhythm of heartbeat by sending out waves of electrical activity to atrial walls. like a pacemaker - atrio-ventricular node (AVN): responsible for passing waves of electrical activity on to the bundle of His. has a slight delay before AVN reacts to make sure ventricles contract after atria are emptied. found near border of right and left ventricle, still within atria - the bundle of His (group of muscle fibres) is responsible for conducting the waves of electrical activity to the finer muscle fibres in the right and left ventricle walls (purkyne tissue) - purkyne tissue carries the waves of electrical activity into muscular walls of the ventricles. found in the walls of the ventricles

Question 28

describe the process of how the cardiac cycle is controlled.

Answer 28

- SAN releases a wave of depolarisation across the atria which causes them to contract - AVN releases another wave of depolarisation once the first wave reaches it. non-conducting collagen tissue prevents the waves of depolarisation travelling down to the ventricles. - instead, the wave of depolarisation is transferred from the SAN to the AVN which passes the wave onto the bundle of His. there’s a slight delay before the AVN reacts to make sure the ventricles contract after atria is fully emptied - the bundle of His conducts the wave of depolarisation down the septum and to the purkyne tissue - the purkyne tissues carry the the waves of depolarisation into the right and left ventricles causing them to contract simultaneously - cells repolarise, cardiac muscle relaxes

Question 29

describe an electrocardiograph.

Answer 29

- machine that records the electrical activity of the heart - the changes in electrical activity in the heart is recorded by the electrocardiograph using electrodes placed on the chest - the trace produced by the electrocardiograph is called an electrocardiogram (ECG)

Question 30

what are the four parts of an electrocardiogram in one full heartbeat?

Answer 30

- P wave, caused by the contraction of the atria - QRS complex - main peak of the heartbeat with dips at either side. caused by the contraction of the ventricles - T wave, due to relaxation of the ventricles - height of wave, indicates how much charge is passing through the heart. bigger wave = more electrical charge = stronger contraction

Question 31

what are the four key abnormal heart rhythms? describe them.

Answer 31

- tachycardia: heart is beating over 100bpm. normal during exercise but abnormally fast whilst resting - bradycardia: heart is beating at less than 60 bpm. common in athletes because they are so fit their cardiac muscle can contract harder and therefore fewer contractions are needed. if heart rate drops too low, an artificial pacemaker is needed to regulate heart rate - fibrillation: very irregular and chaotic rhythm of the heart - ectopic heartbeat: additional heartbeats that are not in rhythm. will. show up on an ECG aas two heartbeats close together, followed buy normally spaced heartbeats. common to occur once a day but if regular if indicate a serious health condition

Question 32

what are the features of haemoglobin?

Answer 32

- large protein w/ a quaternary structure, each polypeptide chain has a haem group which contains iron and gives haemoglobin its red colour - high affinity for oxygen, each molecule carries 4 oxygen molecules - oxygen joins to the iron in haemoglobin to form oxyhaemoglobin. this is a reversible reaction

Question 33

haemoglobin saturation depends on the partial pressure of oxygen. what is partial pressure of oxygen?

Answer 33

- partial pressure of oxygen (pO2) is a measure of oxygen concentration. greater concentration of dissolved oxygen in cells = higher partial pressure - similarly, partial pressure of carbon dioxide is a measure of the CO2 in a cell

Question 34

how and why does haemoglobins affinity vary depending on the partial pressure of oxygen?

Answer 34

- oxygen loads onto haemoglobin, forming oxyhaemoglobin where there’s a high pO2, oxyhaemoglobin unloads its oxygen when there’s a low pO2 - oxygen enters blood capillaries at alveoli which has a high pO2 so oxygen loads onto haemoglobin, forming oxyhaemoglobin - cells respiring lowers pO2, red blood cells deliver oxyhaemoglobin to respiring tissues, where it unloads its oxygen. haemoglobin returns to the lungs for more oxygen

Question 35

what does the oxygen dissociation curve show?

Answer 35

- shows how saturated the haemoglobin is with oxygen at any given partial pressure

Question 36

describe an oxygen dissociation curve

Answer 36

- 100% saturation = every haemoglobin molecule is carrying the max amount of oxygen molecules (4). 0% saturation = no haemoglobin molecule is carrying oxygen - where pO2 is high (alveoli), haemoglobin has a high affinity for oxygen - it will readily combine with oxygen so it has a high saturation of oxygen - where pO2 is low (respiring tissue), haemoglobin has a low affinity for oxygen, its releasing oxygen instead of combining with it. so it has a low saturation of oxygen

Question 37

describe the shape of an oxygen dissociation curve

Answer 37

- graph is S-shaped because when haemoglobin combines with the first O2 molecule, its shape alters in a way that makes it easier for other molecules to join. as the haemoglobin gets more saturated, it becomes harder for more oxygen molecules to join - because of this, the curve has a steep bit in the middle where its easy for oxygen molecules to join, and the shallow parts at each end where its harder - when the curve is steep a small change in pO2 causes a big change in the amount of oxygen carried by the haemoglobin

Question 38

describe the oxygen dissociation curve for fetal and adult human haemoglobin. why is the difference between them important?

Answer 38

- adult haemoglobin and fetal haemoglobin have different affinities for oxygen, fetal haemoglobin has a higher affinity for oxygen at the same partial pressure of oxygen as the fetus’s blood is better at absorbing oxygen than its mothers blood. - the difference is important because: - fetus gets oxygen from mothers blood across the placenta, by the time mothers blood reaches placenta, the oxygen saturation has decreased - for the fetus to get enough oxygen to survive its haemoglobin has to have a higher affinity for oxygen so it takes up enough - if its haemoglobin had the sam affinity for oxygen it wouldn’t be saturated enough

Question 39

describe the process of how CO2 affects blood pH

Answer 39

1. most of the CO2 from respiring tissues diffuses into red blood cells cells, it reacts. with water to form carbonic acid which is catalysed by carbonic anhydrase. (rest of the CO2 binds directly to haemoglobin and is brought to the lungs) 2. carbonic acid dissociates, giving hydrogen ions and hydrogencarbonate ions. 3. increase in hydrogen ions = oxyhaemoglobin unloads its oxygen, so haemoglobin can take up the hydrogen ions, forming haemoglobinic acid. (process stops hydrogen ions from increasing cells acidity) 4. hydrogen carbonate ions diffuse out of red blood cells and are transported in the blood plasma. due to the loss of hydrogen carbonate ions from red blood cells, chloride ions diffuse into red blood cells (chloride shift); this prevents any change in pH that could affect the cells 5. blood reaches the lungs, the low pCO2 levels causes some of the hydrogencarbonate and hydrogen ions to recombine into CO2 and water. this CO2 diffuses out into the alveoli and is breathed out

Question 40

what is The Bohr Effect

Answer 40

- CO2 levels increase, dissociation curve shifts ‘right’. this shows that more oxygen is released from the blood because the lower the saturation of of haemoglobin with O2, the more O2 is released.