2.4 Adaptations for transport of animals Flashcards
1
Q
What components does an effective transport system have?
A
- A transport medium, e.g. blood
- Most organisms have haemoglobin, which has a high affinity for oxygen
- Blood vessels including capillaries, arteries, veins, arterioles and venioles
- A muscular pump, e.g. heart
- Valves for unidirectional flow of blood.
2
Q
How is blood transported in an open circulatory system?
A
In an open circulatory system, blood is not transported in blood vessels but bathes the tissues in a body cavity called the haemocoel.
3
Q
Give an example of an organism with an open circulatory system.
A
Insects
4
Q
Describe the circulatory system of an insect.
A
- A long, dorsal aorta runs the length of the body.
- Blood is pumped at low pressure into the haemocoel where exchange of materials occurs
- Blood returns slowly to the tube-shaped heart portion, which are areas with thickened muscular walls.
- There are no RBCs as the oxygen is delivered directly to the respiring tissues by the tracheae. The fluid is called haemolymph
5
Q
What is the haemolymph?
A
Insect’s equivalent to blood.
Called haemolymph because it doesn’t have haemoglobin
6
Q
Explain how an insect can have a circulatory system which functions at low pressure despite having a high demand for oxygen.
A
The tracheoles directly transport oxygen to the respiring tissues. The circulatory system is not directly involved in the gaseous exchange process.
7
Q
What is a closed circulatory system?
A
Where the blood moves in blood vessels
8
Q
What is the advantage of a closed circulatory system?
A
- Blood is transported at higher pressure.
- Blood can be transported further.
9
Q
What are the two types of closed circulatory systems?
A
Single circulatory system
Double circulatory system
10
Q
What is a single circulatory system?
A
Where the blood moves through the heart once in one complete circuit of the body.
e.g. in earthworm and fish
11
Q
Describe the circulatory system in an earthworm.
A
- Blood moves forward in the dorsal vessel and back through the ventral vessel.
- Thickened, muscular walled blood vessels called pseudohearts pump the blood.
- Earthworm has blood containing haemoglobin which has high affinity for oxgygen, so improves efficiency of oxygen transportation.
12
Q
How many chambers does a fish heart have?
A
2
1 atrium, 1 ventricle.
13
Q
State the benefit of the simplicity in structure of the fish’s heart.
A
The simplicity in structure makes it less likely to encounter any damage as it operates at lower pressure.
14
Q
Describe the blood circulation in fish.
A
Deoxygenated blood is pumped under high pressure from the ventricle to the gill capillaries via the afferent arteries.
Oxygenated blood is then pumped under low pressure and low flow rate to the tissues via efferent arteries. This is due to the increased total cross-sectional surface in the gill capillaries, increasing friction and resistance to flow which decreases pressure.
15
Q
Does the blood of the fish have haemoglobin?
A
Yes
16
Q
State a disadvantage of single circulation.
A
Oxygenated blood is transported under lower pressure, so flow rate is slower.
17
Q
What is a double circulatory system?
A
Where blood passes through the heart twice in one complete circuit of the body
18
Q
Give an example of organisms with a double circulatory system.
A
Mammals
19
Q
Describe what happens in a double circulatory system.
A
A muscular heart pumps oxygenated blood at high pressure and with a high flow rate to the body.
Haemoglobin in the RBCs increases the oxygen carrying capacity.
Tissue fluid is formed to enable exchange of materials with body tissues.
20
Q
State the advantages of double circulation.
A
- Oxygenated blood and deoxygenated blood are kept separate.
- Blood is at different pressures in both circuits. High pressure in the systemic circuit to ensure tissue fluid formation and lower pressure in the pulmonary circuit to avoid tissue fluid formation.
21
Q
What happens if there is a hole in the septum of the heart?
A
Oxygenated and deoxygenated blood can mix.
Causes high anaerobic respiration, high breathlessness and low activity.
22
Q
Why is blood in systemic circuit in high pressure?
A
To ensure that oxygenated blood reaches our respiring tissues faster.
Because oxygenated blood reenters the heart before being pumped to the rest of the body so it is at high pressure.
23
Q
How many chambers does a mammalian heart have?
A
4
24
Q
What is the pulmonary circuit?
A
heart –> lungs —> heart
25
What is the systemic circuit?
heart ---> body ----> heart
26
Why is double circulation efficient?
As it enables oxygenated blood to be pumped around the body at high pressure.
27
What are the three main types of vessels?
Arteries
Capillaries
Veins
28
Draw and label the structure of the artery.
29
What does artery transport blood to and from?
Transports oxygenated blood from the heart to the rest of the body under high pressure and high flow rate
30
State the function of the tunica externa/adventitia.
Has lots of collagen fibres/connective tissue
This prevents the arteries and veins from overstretching
31
How is the tunica media different in the artery compared to the vein?
It is thicker in the artery than in a vein
32
What is the tunica media made up of?
Smooth muscle and elastic fibres
33
State the function of the smooth muscle in the tunica media.
enables arteries to withstand high pressure
34
State the function of eleastic fibres in the tunica media.
Can contract and relax to alter the diameter of the lumen.
They recoil which decreases volume and increase pressure in artery to push blood.
35
State the function of the Tunica Intima and Smooth endothelium.
reduces friction between the blood and the inner surface of the artery and vein
36
State the function of the vein.
Transports oxygenated blood from the respiring tissues to the heart under low pressure and slower flow rate
37
Draw and label the structure of the vein.
38
How is the tunica media different in the vein compared to artery?
Thinner than artery since it does not need to withstand high pressure.
low pressure because further away from heart
39
State the function of valves.
To prevent the backflow of blood.
They are semilunar valves
40
How are arteries and veins connected?
Arteries branch into smaller arteries called arterioles.
They then further subdivide into capillaries.
Capillaries re-join to form venules which further rejoin to form veins.
41
How does the tunica media of arterioles enable vasodilation and vasoconstriction?
They have a thicker layer of smooth muscle to enable vasodilation and vasoconstriction.
42
What do the capillaries do?
Capillaries form a vast network that transport blood to all organs of the body, allowing the exchange of materials to occur.
43
Why does venous blood flow at a slower velocity?
Veins have a large diameter lumen, so blood travels at a slower velocity and at lower pressure.
This means that venous blood has the tendency to flow backwards.
To counter this, they contain semi-lunar valves to prevent backflow of blood.
44
What happens if the semi-lunar valves fail?
Failure in the functioning of these valves can lead to varicose veins and even heart failure
45
How do calf muscles help upward blood flow?
When the muscle contracts, it pinches the vein, decreasing the diameter of the lumen, increasing the pressure, pushing the blood back up to the heart.
46
State the function of capillaries.
Transport both oxygenated and deoxygenated blood as they are the link between arterioles and venioles.
47
How is the capillary adapted?
Single layer of endothelial cells surrounded by a basement membrane, to provide a short diffusion pathway.
Endothelial layer is fenestrated, making walls permeable to enable the exchange of materials - water and solutes diffuse out and waste products diffuse back in.
Narrow diameter and are numerous, increasing total S.A., also increases resistance to blood flow, so velocity of flow decreases, allowing time for exchange of materials.
Capillaries have a slightly smaller diameter than a RBC so the RBCs have to bend to squeeze through.
48
What is the heart made of?
The specialised muscular tissue, known as cardiac muscle.
49
How is the cardiac muscle different from the skeletal muscle?
Cardiac muscle never tires.
50
Why is the heart said to be myogenic?
The heartbeat is initiated within the muscle cells and can contract without any external stimulation.
51
How can the heartbeat be altered?
By nervous and hormonal stimulation.
52
Which side of the heart pumps deoxygenated blood?
The right-hand side pumps deoxygenated blood to the lungs
53
Which side of the heart pumps blood to the rest of the body?
The left side carries oxygenated blood to the body.
54
Label the diagram of the heart.
55
What are the stages of the cardiac cycle?
Atrial systole
Ventricular systole
Diastole
56
How long do each of the stages of the cardiac cycle last for?
0.8 seconds
57
What happens during atrial systole?
1. Thin-walled atria contract, increasing the blood pressure
2. The atrioventricular valves (bicuspid and tricuspid) open due to the pressure the atria exceeding the pressure in the ventricles.
3. Blood flows out of the atrium and into the ventricle
4. The semi-lunar valves are closed.
58
What happens during ventricular systole?
1. The thick muscular walls of the ventricles contract, from the apex upwards, decreasing their volume, increasing their pressure. The pressure in the ventricles quickly exceed atrial pressure so the blood backflows, hitting the atrio-ventricular valves forcing them closed. This causes the first heart sound, 'lub'
2. The pressure in the aorta and pulmonary artery is still higher than the ventricles so the semi-lunar valves remain closed. At this point, there is no movement of blood in the ventricles as both sets of valves are closed.
3. Ventricles continue to contract, increasing pressure. Eventually the pressure in the ventricles exceed that of the aorta and pulmonary artery. At this point the pressure of the blood against the semi-lunar valves forces them open. Now the blood is allowed to leave
4. Pulmonary artery carries deoxygenated blood to the lungs and the aorta carries oxygenated blood to the different parts of the body.
59
What happens during diastole?
1. Ventricles relax.
2. As the volume increases, the pressure inside the ventricles drops below that in the arteries
3. This causes blood to flow backwards, which closes the semi-lunar valves, preventing blood from going back into the ventricles. This produces the second part of the heart sound. 'dub'
4. Blood from the vena cava and the pulmonary veins passively enters the atria, which are relaxed. The whole cycle then starts again.
60
What happens at the end of diastole?
blood moves into the heart
61
Which valves are open/closed in atrial systole?
Bicuspid and Tricuspid valves are open
62
Which valves are open/closed in early ventricular systole?
Bicuspid and Tricuspid valves are closed
63
Which valves open in late ventricular systole?
Semi-lunar valves
64
Which valves close in diastole?
Semi-lunar valves
65
Draw a graph for the changes in pressure in the left-hand side of the heart.
66
What acts as a pacemaker in the heart?
The wall of the right atrium has a cluster of specialised cardiac cells called the sino-atrial node (SAN) that acts as a pacemaker.
67
How is ventricular systole stimulated?
The SAN generates an electrical impulse or a wave of excitation which spreads across the walls of the atria, depolarising them, stimulating atrial systole.
A layer of connective tissue insulates the ventricles apart from another cluster of cells, the atrio-ventricular node (AVN). This introduces a delay in the transmission of the electrical stimulation.
The AVN passes the wave of excitation down the septum via nerves of the bundle of His, to the apex of the heart. It then transfers up the Purkinje fibres in the outer muscular walls of the ventricles.
This stimulates ventricular systole from the apex upwards, pushing the blood up and out of the heart into the aorta and pulmonary artery
68
Why is the delay necessary?
So that the atria complete their contraction and empty with blood before the ventricle starts to contract
69
What is the electrocardiogram?
A trace of the voltage changes that occurs in the heart, detected by electrodes on the skin.
70
Draw an electrocardiograph.
71
What does the P wave show?
Depolarization of atria in response to SA node triggering
These waves are snall due to thin muscular walls
72
What is the PR interval?
Time bwteen start of P wave and start of QRS complex.
Shows the delay of AV node to allow the filling of ventricles.
73
What does QRS complex show?
Depolarization of ventricles, triggers main pumping contraction.
Amplitude is larger due to thick muscular walls
74
What does the T wave show?
Repolarization of the ventricle muscles.
75
What is the ST segment?
The period of time between end of S wave and start of T wave
76
What is the isoelectric line?
horizontal line after T wave.
Is the baseline voltage
77
State two differences between the normal trace and a person suffering from atrial fibrillation.
In atrial fibrillation, QRS complexes are irregular.
Many P-waves per cycle in atrial fibrillation, while in normal trace there is one P-wave per heart beat
In atrial fibrillation, heart rate is greater than normal.
78
Talk about the blood pressure changes in the systemic and pulmonary circulatory system.
Pressure in the aorta, ventricles and pulmonary artery is pulsatile due to the close proximity to the heart: the peak is due to ventricular systole, the trough is due to diastole
The largest drop in pressure occurs in the arterioles due to an increase in total surface area, increasing the friction and resistance to flow. This occurs despite having a narrower lumen. The pressure can be altered with vasoconstriction/vasodilation
Pressure drops further in the capillaries due to :
- a further increase in total surface area of the capillary bed
- leakage of tissue fluid resulting in less volume and therefore less pressure
Pressure in veins and venules remains low due to a large lumen and the distance from the heart
79
Why are erythrocytes (RBCs) red?
Due to the presence of haemoglobin
80
State the function of erythrocytes.
The transport of oxygen from the lungs to the respiring tissue
81
How are RBCs adapted to their function?
1. Can change shape to fit through capillaries
2. Biconcave; large surface area for diffusion of oxygen
3. No nucleus to carry more haemoglobin
4. Short at the centre to provide a short diffusion pathway
82
What are the two main groups of leucocytes (WBCs)?
Agranulocytes
Granulocytes
83
What are agranulocytes?
They have a clear cytoplasm and spherical nucleus. They produce antibodies and anti toxins and are therefore responsible for immunity
84
What are granulocytes?
They have a granular cytoplasm and lobed nucleus. They are involved in the first line of defence, mainly phagocytosis
85
What is plasma?
A pale-yellow liquid.
approx 90% water containing many solutes like blood proteins, nutrients, hormones and electrolytes
Plasma also distributes heat released during respiration to prevent enzymes from becoming denatured.
86
How does haemoglobin bind to oxygen?
Haemoglobin binds to oxygen via cooperative binding
4O2 + Hb ------> HbO8
when the 1st molecules of oxygen binds to the iron group, it changes the shape of haemoglobin, making it easier for the second molecule to bind.
When the 2nd one binds, it also changes the shape of haemoglobin, making it easer to bind the 3rd oxygen.
Binding of 3rd oxygen has no effect on the shape so it takes a large amount of partial pressure to bind the 4th oxygen molecule.
87
Draw and explain the oxygen dissociation curve for adult haemoglobin.
At high partial pressures, haemoglobin has a high affinity for oxygen. It therefore binds readily and does not release oxygen readily (95% saturation)
As partial pressures of oxygen decrease, the affinity of haemoglobin for oxygen also decreases. Oxygen is therefore released or dissociated readily to the respiring tissues to maintain aerobic respiration.
The steep part of the graph shows that a very small drop in oxygen partial pressure leads to a large drop in % staturation of haemoglobin
88
Why is the oxygen dissociation relationship of haemoglobin not linear?
In a sigmoid relationship:
- At all partial pressures a higher % saturation is acheived
- can achieve 95-98% saturation at lower partial pressures
In a linear relationship, a change in partial pressure in oxygen would not result in a large % change of saturation of haemoglobin
89
Draw and explain the oxygen dissociation curve for foetal haemoglobin.
Curve to the left of adult haemoglobin
Higher affinity for oxygen than adult haemoglobin and higher % saturation at all partial pressures
Oxygen can be absorbed from maternal haemoglobin to foetal haemoglobin in the placenta
90
Draw and explain the oxygen dissociation curve of myoglobin.
To the left of foetal haemoglobin
Extremely high affinity for oxygen and only dissociates during intense physical activity when partial pressures of oxygen are very low
Has a higher % saturation at all partial pressures of oxygen compared to adult haemoglobin
Only single haemoglobin unit therefore only binds to one molecule of oxygen
Acts as an oxygen store in muscle cells
A small decrease in partial pressure of oxygen results in an extremely large decrease in saturation of myoglobin
91
What are the advantages of training at high altitudes?
Number of RBCs increase, so number of haemoglobin molecules increase, so more oxygen transported to respiring tissues, so more oxygen for respiration, so more ATP allowing athletes to improve their performance
92
Talk about the oxygen dissociation curve of the llama
Graph to the left of human haemoglobin
Llama's live in habitats where there is lower partial pressure because they live in high altitudes.
Oxygen dissociation curve is to the left of adult haemoglobin.
Llama's haemoglobin has a higher affinity for oxygen
Reaches 95% saturation at a lower partial pressure (able to reach 95-98% saturation in the partial pressure of o2 available in its habitat)
When partial pressure reduces, does not readily dissociate o2 to respiring tissues because of haemoglobin's high affinity in llama. carries out less aerobic respiration at lower partial pressures.
93
Talk about the oxygen dissociation curve of the lugworm.
Graph to the left of llama oxygen dissociation curve
Lives in an area with low oxygen availability, so low partial pressure.
Haemoglobin has high affinity for oxygen
So can reach 95-98% saturation at the lower partial pressures available in habitat.
At low partial pressures, it does not dissociate oxygen as readily.
Has external gills which increases SA for gas exchange
Flow of water in one direction over burrow to maintain concentration gradient. Counter-current flow, maintains high concentration gradient over the entire gill lamella/surface
94
Explain the Bohr effect.
The Bohr effect promotes the release of oxygen molecules to respiring tissues.
Active respiration releases carbon dioxide, causing the partial pressure of carbon dioxide to increase.
This increases acidity levels, lowering pH due to formation of H+ ions
H+ ions bind to oxyhaemoglobin, causing change in shape, lowering haemoglobin affinity for oxygen, shown as a shift to the right on the oxygen dissociation curve.
Oxygen is then released from oxyhaemoglobin to respiring tissues so aerobic respiration can be maintained.
95
List 3 ways carbon dioxide is transported in blood.
1. 5% dissolved in plasma
2. 10% bound to haemoglobin as carbamino haemoglobin
3. 85% as hydrogen carbonate ions
96
How is carbon dioxide transported in RBCs?
1. Carbon dioxide in the blood diffuses into the red blood cell
2. Carbonic anhydrase enzyme catalyses the addition of carbon dioxide to water, forming carbonic acid.
3. Carbonic acid dissociates to form hydrogen ions and hydrogen carbonate ions
4. Hydrogen carbonate ions diffuse out of the red blood cell into the plasma. To negate the outward flow of the negative hydrogen carbonate ions, chloride ions diffuse into the red blood cell from the plasma. This is called the chloride shift and occurs to maintain electrochemical neutrality
5. Hydrogen ions bind to oxyhaemoglobin at an allosteric site, changing the shape of the haemoglobin molecule, lowering its affinity for oxygen, which is then dissociated. The hydrogen ions that are bound to haemoglobin form haemoglobinic acid, HHb. This removes hydrogen ions and therefore acts as a buffer to maintain the pH within the red blood cell.
6. Oxygen diffuses out of the cell and into the respiring tissues
97
What is tissue fluid?
Blood plasma minus the plasma proteins
98
What is the function of tissue fluid?
1. To supply tissues with oxygen and other solutes , e.g. glucose, fatty acids, salts, hormones and amino acids to respiring tissues
2. To transport waste products such as carbon dioxide and, in the liver, urea, move from the cells to the blood
99
How are capillaries adapted for exchange of substances?
1. Have fenestrations to allow substances to move out
2. Only a single endothelial cell thick
3. Have a close relationship with body tissues/systems
100
Draw a diagram to show how tissue fluid is formed.
101
What causes kwashiorkor?
A diet lacking in protein.
This results in fewer plasma proteins which raises the water potential of the blood plasma. This in turn reduces water potential gradient so less is reabsorbed by osmosis resulting in severe oedema
102
What does kwashiorkor result in?
swollen limbs, face and abdomen.
