Transport in Animals Flashcards
1
Q
why do multicellular organisms need a transport system?
A
- they have a small SA:V ratio, larger diffusion distance and a high metabolic rate meaning diffusion is not sufficient
- they are very active meaning their cells are respiring very quickly, needing a constant, rapid supply of oxygen and glucose and a fast removal of carbon dioxide
therefore, a transport system is needed to ensure every cell has a sufficient supply of substances and has its waste products removed
2
Q
what is the circulatory system?
A
an organ system that permits blood to circulate
3
Q
what is a circulatory system used for in mammals?
A
- to carry glucose and oxygen around the body
- to transport hormones, antibodies and waste products (e.g. carbon dioxide)
4
Q
what is the function of blood?
A
- it is a tissue which transports many vital components around the organism, to and from the cells
- this is to enable respiration, fight diseases, supply nutrients, and maintain homeostasis (e.g. stabilize temperature and pH)
5
Q
name 5 substances that blood transports
A
- oxygen
- glucose
- carbon dioxide
- hormones
- blood cells
6
Q
what are the 4 different types of circulatory system?
A
- open
- closed
- single
- double
7
Q
what is an open circulatory system?
A
blood isn’t enclosed in blood vessels all the time but flows freely through the body cavity
8
Q
describe the blood in an open circulatory system
A
- doesn’t need red blood cells for transportation
- made up of haemolymph so is a yellow color
- moving slow
- slow oxygen delivery (not sufficient for high metabolisms)
9
Q
which animals have an open circulatory system?
A
some invertebrates (e.g. insects)
10
Q
what is a closed circulatory system?
A
blood is enclosed in blood vessels
11
Q
describe the blood in a closed circulatory system
A
- made up of red blood cells and haemoglobin so is a red color
- moving faster
- more sufficient delivery of oxygen
12
Q
which animals have a closed circulatory system
A
all vertebrates (e.g. fish and mammals)
13
Q
what is a single circulatory system?
A
blood only passes through the heart once for each complete circuit of the body
14
Q
describe the blood in a single circulatory system
A
- low pressure
- moving slow
- supplying limited oxygen and glucose to respiring cells
15
Q
give an example of an animal that has a single circulatory system?
A
fish
16
Q
what is a double circulatory system?
A
blood passes through the heart twice for each complete circuit of the body
17
Q
describe the blood in a double circulatory system
A
- high pressure
- moving fast
- supplying sufficient oxygen and glucose to respiring cells
18
Q
give an example of an animal that has a double circulatory system?
A
mammals (e.g. humans)
19
Q
what are the 6 main components of a double circulatory system
A
- heart
- pulmonary circulatory system (lungs)
- systematic circulatory system (body)
- veins
- capillaries
- arteries
20
Q
what is an advantage of a double circulatory system?
A
it maintains the blood pressure in both the pulmonary and systematic circulatory system
21
Q
name the 5 blood vessels
A
- arteries
- arterioles
- capillaries
- venules
- veins
22
Q
what is the structure of the arteries?
A
- thick and muscular walls
- walls contain fibrous tissue
- the walls contain elastic tissue to stretch and recoil as the heart beats
- it has a folded endothelium (inner lining) to allow the artery to expand
- narrow lumen
- all of this helps maintain high blood pressure (preventing it flowing backwards)
23
Q
what is the function of the arteries?
A
to carry oxygenated blood from heart to body at high pressure
24
Q
which artery is an exception to the usual function
A
pulmonary artery - carries deoxygenated blood to the lungs
25
what is the structure/function of the arterioles?
- arteries branch into arterioles
- they are much smaller than arteries
- they have a layer of smooth muscle but less elastic tissue
- this allows them to contract/expand, controlling the amount of blood flowing to tissues
26
what is the structure of the capillaries?
- arterioles branch into capillaries
- they are the smallest blood vessel
- they are adapted for sufficient exchange/diffusion
- their endothelium is one cell thick
- very narrow lumen (for 1 RBC)
27
what is the function of the capillaries?
site of exchange of substances (e.g. glucose and oxygen) between cells and capillaries
28
how are capillaries adapted for efficient exchange?
- walls are 1 cell thick (short dd)
- narrow lumen (short dd)
- gaps in endothelium to allow exchange of materials
-
-
29
what is the structure of the venules?
- capillaries connect to venules
- they have very thin walls
- their walls contain some muscle cells
30
what is the function of the venules?
they join together to form veins
31
what is the structure of the veins?
- wide lumen (less resistance to blood flow)
- very little elastic/muscle tissue
- contains valves to prevent backflow of blood
- thin walls (mainly fibrous tissue) as blood is at low pressure
32
what is the function of the veins?
to carry deoxygenated blood from body to heart at low pressure
33
which vein is an exception to the usual function
pulmonary vein - carries oxygenated blood from lungs to heart
34
name the 2 valves
- atrioventricular valves (bicuspid and tricuspid)
- semi-lunar valves
35
where are the atrioventricular valves found?
between the atria and the ventricles
36
what is the function of the atrioventricular valves?
to stop backflow when ventricles contract
37
where are the semi-lunar valves found?
between the pulmonary artery and the aorta
38
what is the function of the semi-lunar valves?
to stop backflow when ventricles relax
39
how do valves prevent backflow?
- they are forced open when there is higher blood pressure behind the valve
- they are forced shut when there is a higher blood pressure in front of the valve
40
label the external structure of the heart
p183
41
label the internal structure of the heart
p183
42
which side of the heart muscle is thicker and why?
the left side of the heart muscle is thicker as the blood has to be pumped all the way around the body so the ventricle needs a bigger force (gained by a bigger contraction)
43
why is the atrium muscle thinner than the ventricle muscle?
because the atrium only needs to pump blood to the ventricle whereas the ventricle needs to pump blood into the blood vessels
44
what is tissue fluid?
the fluid that surrounds cells in tissues
45
what is tissue fluid made from?
substances that leave the blood plasma (e.g. oxygen, water and nutrients)
46
what is blood plasma?
the liquid that carries everything in the blood
47
why doesn't tissue fluid contain red blood cells or BIG proteins?
because they are too large to be pushed out through the capillary walls
48
how is tissue fluid formed?
by the interaction between hydrostatic pressure and osmotic/oncotic pressure
49
what substances do cells take in from tissue fluid?
- oxygen
- nutrients
50
what substance do cells release into tissue fluid?
metabolic waste
51
how do substances move into the tissue fluid?
they move out of the capillaries, into the tissue fluid by pressure filtration
52
what is hydrostatic pressure?
the pressure exerted by a liquid - think blood pressure
53
what happens to hydrostatic pressure during pressure filtration?
- at the arteriole end of the capillary bed (nearest the arteries), the hydrostatic pressure inside the capillaries is greater than that in the tissue fluid
- therefore, the high pressure forces fluid (from the blood plasma) out of the capillaries into the spaces around the cells, forming tissue fluid
- as the fluid leaves, the hydrostatic pressure inside the capillaries decreases, meaning it is much lower at the venule end of the capillary bed (nearest the venules)
54
what is osmotic/oncotic pressure?
- in the blood, there are proteins, blood cells, and other materials which means there is a low water potential
- this causes osmotic/oncotic pressure
- it is generated by plasma proteins in the capillaries
55
what happens to osmotic/oncotic pressure during pressure filtration?
- as water leaves the capillaries, the concentration of plasma proteins in the capillaries increases, decreasing water potential
- therefore, there is a lower water potential in the capillaries than in the tissue fluid so some water re-enters the capillaries at the venule end via osmosis (osmotic/oncotic pressure)
- osmotic/oncotic pressure does not change
56
summarize the movement of fluid at the arteriole end
hydrostatic pressure > osmotic/oncotic pressure so fluid is forced out of the capillaries via hydrostatic pressure
57
summarize the movement of fluid at the venule end
osmotic/oncotic pressure > hydrostatic pressure so water re-enters the capillaries via osmosis
OSMOTIC PRESSURE DOES NOT CHANGE BUT HYDROSTATIC PRESSURE DOES WHICH CAUSES THE DIFFERENCE
58
why is there excess tissue fluid after pressure filtration?
not all of the tissue fluid re-enters the capillaries at the venule end
59
what happens to excess tissue fluid?
- it drains into lymph vessels
- once inside, the fluid is called lymph
- lymph gradually moves towards the main lymph vessels in the thorax (chest cavity) and backflow is prevented by valves
- from the thorax, it is returned to the blood near the heart
this is called the lymphatic system
60
what is the lymphatic system?
a drainage system made up of lymph vessels
(a part of the immune system)
61
what is the composition of blood?
- red blood cells
- white blood cells
- platelets
- proteins
- water ( but less water potential than tissue fluid or lymph)
- dissolved solutes (e.g. salt)
62
what is the composition of tissue fluid?
- very few white blood cells (they only enter if there is an infection)
- platelets only present if capillaries are damaged
- very few proteins (plasma/big proteins are too big to leave through capillary walls)
- water
- dissolved solutes (e.g. salt)
63
what is the composition of lymph?
- white blood cells
- proteins (only antibodies)
- water
- dissolved solutes (e.g. salt)
64
what are platelets?
small fragments of cells that play an important role in blood clotting
65
heart dissection
p184
66
summarize how blood is pumped around the body
67
what is the cardiac cycle?
an ongoing sequence of contraction and relaxation of the atria and ventricles that keeps blood continuously circulating around the body
68
name the stages of the cardiac cycle
- atrial systole
- early ventricular systole
- late ventricular systole
- early ventricular diastole
- late ventricular diastole
69
what happens during atrial systole?
- ventricles are relaxed
- atria contract (decreasing the atrial volume and increasing atrial pressure)
- this pushes blood through the AV valves into the ventricles (ventricular pressure and volume increase slightly as they receive the blood)
- therefore the AV valves are open
- semilunar valves are closed
70
what happens during early and late ventricular systole?
- atria relax
- ventricles contract (decreasing the ventricular volume and increasing ventricular pressure)
- this pushes blood through the SL valves into the pulmonary artery (R) and aorta (L)
- therefore the SL valves are open
- the higher pressure in the ventricles than the atria forces the AV valves shut to prevent back flow
71
what happens during early and late ventricular diastole?
- ventricles and atria relax
- the higher pressure in the pulmonary artery and aorta than in the ventricles forces the SL valves shut to prevent back flow
- blood returns to the heart and fills the atria again due to a higher pressure in the vena cava and pulmonary vein
- this increases the atrial pressure and the ventricular pressure decreases as the ventricles continue to relax
- the higher pressure in the atria causes the AV valves to open
- this allows blood to start flowing passively (without contraction) into the ventricles
- when the atria contract, the process begins again (atrial systole)
72
where does the 'lub-dub' sound come from in a heart beat?
'lub' - AV valves closing (ventricular systole)
'dub' - SL valves closing (ventricular diastole)
73
what does systole mean?
contract
74
what does diastole mean?
relax
75
summarize how blood is pumped around the body
76
the cardiac muscle is myogenic, what does this mean?
it means the cardiac muscle can contract and relax automatically, without receiving signals from nerves
this pattern of contractions controls the regular heartbeat
77
where does the process of controlling the heartbeat start?
sino-atrial node (SAN) - in the wall of the right atrium
78
what is the role of the sino-atrial node (SAN)?
- it acts as a pacemaker
- it sets the rhythm of the heartbeat by sending regular waves of electrical activity over the atrial walls
- this causes the left and right atria to contract at the same time
- a band of non-conducting collagen tissue prevents the waves of electrical activity from being passed directly from the atria to the ventricles
- instead, these waves are transferred from the sino-arial node (SAN) to the atrioventricular node (AVN)
79
what is the role of the atrioventricular node (AVN)?
- it is responsible for passing the waves of electrical activity (received from the SAN) onto the bundle of His
- however, there is a slight delay before the atrioventricular node (AVN) reacts, to make sure the ventricles contract after the atria have emptied
80
what is the bundle of His?
a group of muscle fibres
(p187 diagram of location)
81
what is the bundle of His responsible for?
conducting the waves of electrical activity to the Purkyne tissue
82
what is the Purkyne tissue?
finer muscle fibres in the right and left ventricle walls
83
what is the role of the Purkyne tissue?
it carries the waves of electrical activity into the muscular walls of the right and left ventricles
- this causes them to contract simultaneously, from the bottom up (forcing blood into the aorta and pulmonary artery)
84
summarize how the heart beat is controlled (how the waves of electrical activity are passed through the heart)
1. the SAN sets the heart rhythm by sending waves of electrical activity over the atrial walls
2. this causes the atria to contract simultaneously
3. these waves are transferred to the AVN
4. the AVN passes these onto the bundle of His (with a slight delay to ensure the atria have emptied)
5. the bundle of His conducts these waves onto the Purkyne tissue
6. the Purkyne tissue carries the waves to the left and right ventricle walls
7. this causes the ventricles to contract simultaneously
(p187 diagram)
85
what happens to the hearts electrical charge when it contracts?
- it loses electrical charge
- this means the heart muscle depolarizes
86
what happens to the hearts electrical charge when it relaxes?
- it regains electrical charge
- this means the heart muscle repolarizes
87
how is the electrical activity of the heart recorded?
electrocardiograms (ECGs)
88
what is an electrocardiograph?
a piece of machinery that records the electrical activity of the heart
89
what does a normal electrocardiogram (ECG) look like?
p188
90
what is the P wave?
- contraction (depolarization) of the atria
- this is in response to the SAN triggering
(atrial systole)
91
what is the PR interval?
where the AVN delays to ensure the atria are empty and so that the ventricles have time to fill
92
what is the QRS complex?
- contraction (depolarization) of the ventricles
- this triggers the main pumping contraction (biggest spike in ECG)
(ventricular systole)
93
what is the ST interval?
the beginning of ventricle relaxation (repolarization)
94
what is the T wave?
- relaxation (repolarization) of the ventricles
(diastole)
95
what does the flat line on an ECG represent between each heartbeat?
where the heart is relaxing and filling up with blood
96
what does the height of an ECG wave indicate?
how much electrical charge is passing through the heart
(a bigger wave means more electrical charge so a bigger contraction)
97
what is the average heart rate for a healthy person?
60 - 80bpm
98
what does tachycardia look like on an ECG?
- complexes normal
- evenly spaced
- faster heart rate (>100bpm)
- p189
99
what is the problem with tachycardia?
the heartbeat is too fast meaning the heart isn't pumping blood efficiently
100
what does bradycardia look like on an ECG?
- complexes normal
- evenly spaced
- slower heart rate (<60bpm)
- p189
101
what is the problem with bradycardia?
the heart beat is too slow indicating a problem with the hearts electrical activity
(e.g. there may be something preventing impulses from the SAN being passed on properly)
102
what is ectopic heartbeat?
- an 'extra' heartbeat that interrupts the regular rhythm
- it could be caused by an early contraction of the atria or ventricles
103
what does an ectopic heartbeat look like on an ECG?
- if it is caused by an early contraction of the atria, the P wave will look different and will come in earlier
- if it is caused by an early contraction of the ventricles, the QRS complex would look taller and wider, sometimes without the P wave before it
- p189
(occasional ectopic heartbeats in a healthy person don't cause an issue)
104
what does atrial fibrillation look like on an ECG?
- baseline irregular (missing P wave)
- ventricular response is irregular
- p190
105
what is the problem with atrial fibrillation?
- atria lose their rhythm and stop contracting properly
- as a result, blood is not pumped into ventricles
- it can result in anything from chest pain and fainting to lack of pulse and death
106
what does ventricular fibrillation look like on an ECG?
- rapid, wide irregular ventricular complexes
- p190
107
what is the problem with ventricular fibrillation?
- ventricles lose their rhythm and stop contracting properly
- as a result, blood is not pumped around the body
- it can result in anything from chest pain and fainting to lack of pulse and death
108
?what does arrythmia look like on an ECG?
- all complexes normal
- irregular rhythm
- (abnormal ECG sheet)
109
?what does a heart attack look like on an ECG?
higher S and T wave
110
what adaptations do red blood cells have to allow it to carry as much oxygen as possible?
- no nucleus or organelles
- biconcave shape = larger SA:V ratio
- small and flexible to fit in capillaries
111
what is haemoglobin's structure?
- it is a conjugated/large protein (a globular protein with a prosthetic group)
- it has 4 polypeptide chains (quaternary structure) : 2 alpha chains and 2 beta chains
- each chain has a haem (non-protien) group (its prosthetic group)
112
what does the haem group provide for haemoglobin?
- it contains iron
- it gives haemoglobin its red color
113
where is haemoglobin found?
in red blood cells
114
what is the role of haemoglobin?
to carry oxygen around the body
115
how many oxygen molecules can each molecule of human haemoglobin carry?
4 oxygen molecules (8 oxygen atoms)
116
how and where does oxygen bind to haemoglobin?
in the lungs - oxygen joins to the iron in haemoglobin
117
what is the word and symbol equation for when haemoglobin and oxygen bind?
haemoglobin + oxygen -----> oxyhaemoglobin
Hb + 4O₂ -----> HbO8
118
oxygen binding to haemoglobin is a reversible reaction - what does this mean?
- in the lungs, oxygen joins to the iron in haemoglobin
- then, near the body cells oxygen can leave the oxyhaemoglobin and it turns back into haemoglobin
- this is called loading and dissociation
119
what is oxygen loading?
when an oxygen molecule joins to haemoglobin
120
where does oxygen loading take place?
in the lungs because a steep concentration gradient is maintained to allow oxygen to move into the RBCs (where oxygen concentration is low)
121
what is oxygen dissociation?
when an oxygen molecule leaves oxyhaemoglobin
122
where does oxygen dissociation take place?
at respiring tissues (where oxygen concentration is low) in order for the oxygen to diffuse into the cells
123
what is a key feature of haemoglobin?
it has a high affinity for oxygen
124
what does affinity for oxygen mean?
the tendency a molecule has to let go of its oxygen
- high affinity - holds on to it more
- low affinity - lets go more easily (gives it up to respiring cells)
125
what can have an effect on haemoglobin's affinity for oxygen?
partial pressure (pO₂)
126
what is partial pressure (pO₂)?
a measure of oxygen concentration
(the greater the concentration of dissolved oxygen in cells, the higher the partial pressure)
127
what are the units of partial pressure?
Pa or KPa
128
how does partial pressure affect haemoglobin's affinity for oxygen and when it is loaded or dissociated?
(summary)
- at alveoli (in lungs) ---> high oxygen concentration = high partial pressure of oxygen = steep concentration gradient = high affinity for oxygen = oxygen is loaded
- at respiring tissues ---> low oxygen concentration = low partial pressure of oxygen = shallow concentration gradient = low affinity for oxygen = oxygen is dissociated
129
what does an oxygen dissociation curve show
how saturated the haemoglobin is with oxygen at any given partial pressure (affected by haemoglobin's affinity)
130
draw and describe an oxygen dissociation curve
- p192
- where partial pressure is high (e.g. in the lungs), haemoglobin has a high affinity for oxygen so it has a high saturation of oxygen
- where partial pressure is low (e.g. in respiring tissues), haemoglobin has a low affinity for oxygen so it has a low saturation of oxygen
- over the steep part of the curve, a small drop in partial pressure causes a larger drop in haemoglobin saturation
- 100% saturation is very rare
131
what is the typical partial pressure reading in respiring tissues?
132
at what partial pressure does oxygen loading usually occur at in the lungs?
12-14 KPa
133
why is the dissociation curve an S-shape?
- when an oxygen molecule binds to the ferrous ion in haemoglobin, it physically distorts the haem group slightly
- this makes it easier for the next oxygen molecule to bind
- this continues to happen each time the oxygen binds
- therefore, at lower partial pressures of oxygen, it is more difficult for oxygen to bind but easier at higher partial pressures
134
what is different about foetal haemoglobin compared to adult haemoglobin?
- it has a higher affinity for oxygen (a fetus' blood is better at absorbing oxygen than its mothers blood)
- therefore, it lets go of its oxygen less easily
- otherwise, it wouldn't be able to pick up oxygen from the mothers blood
135
why is it important that a fetus must have a higher affinity of oxygen?
- by the time the mothers blood reaches the placenta, its oxygen saturation has decreased because because some has been used up by the mothers body already
- the placenta has a low partial pressure of oxygen so adult oxyhaemoglobin will dissociate there
- for the fetus to get enough oxygen to survive, it must have a higher affinity for oxygen than adult haemoglobin
- this means it can take up oxygen at a lower partial pressure of oxygen
136
why, after birth, is it important that fetal haemoglobin is replaced by adult haemoglobin?
if the child ever gets pregnant, it will need adult haemoglobin to pass oxygen onto its foetus
137
does myoglobin have a higher or lower affinity for oxygen than haemoglobin?
a higher affinity for oxygen
138
do high-land animal's haemoglobin have a higher or lower affinity for oxygen than low-land animals? why?
high-land animals have a higher affinity for oxygen because at increased heights, the partial pressure of oxygen in the atmosphere/air is lower
139
what is the Bohr effect?
an explanation of why, in the presence of carbon dioxide, haemoglobin's affinity for oxygen is reduced (causing the dissociation curve to shift right)
140
how does the partial pressure of carbon dioxide (pCO₂) effect oxygen dissociation?
- when cells respire, they produce carbon dioxide, increasing its partial pressure
- therefore, at a higher partial pressure of carbon dioxide, haemoglobin gives up its oxygen more readily (shifting dissociation curve to shift right)
- it is a way of getting more oxygen to cells during activity
141
draw the Bohr effect curve
p183
- when the curve shifts to the right, hemoglobin lets go of the oxygen easier (lower affinity)
- and oppositely
142
explain the Bohr effect process
1. most of the carbon dioxide from respiring tissues diffuses into red blood cells
(the rest, around 10%, binds directly to haemoglobin and is carried to the lungs)
2. the carbon dioxide reacts with water inside the red blood cells to form (weak) carbonic acid (H₂CO₃)
this is catalyzed by the enzyme carbonic anhydrase
3. the carbonic acid (H₂CO₃) dissociates into hydrogen ions (H+) and hydrogen-carbonate ions (HCO₃ -)
4. the hydrogen-carbonate ions (HCO₃ -) diffuse out of the red blood cells due to a lower concentration on the outside, and get transported in the blood plasma
5. chloride ions (Cl-) then diffuse into the red blood cell to maintain electroneutrality (charges stay the same as before) - this is the chloride shift and it prevents any pH change that could affect the cells
6. the increase in hydrogen ions (H+) causes oxyhaemoglobin to unload its oxygen so that the haemoglobin can take up the hydrogen ions (H+) - this forms haemoglobinic acid (H+Hb)
7. as its an acid, it changes the pH of the haemoglobin, meaning the protein will change shape, allowing oxygen to be released easier
when the blood reaches the lungs, the low partial pressure of carbon dioxide causes some of the hydrogen-carbonate ions (HCO₃ -) and hydrogen ions (H+) to recombine into carbon dioxide and water
the carbon dioxide then diffuses into the alveoli and is breathed out
the more CO2, the more H+, the more oxygen is released from the haemoglobin
143
what is haemoglobin acting as in the Bohr effect?
a buffer
