Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A Level Biology > Module 3.1.2 Transport In Animals > Flashcards

Module 3.1.2 Transport In Animals Flashcards

modules 4, 2 & 3 :)

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is transport?

A

The movement of substances such as oxygen, nutrients, hormones, waste & heat around the body of an organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What 3 factors influence the need for a transport system?

A

Size
Surface area to volume ratio (SA:V)
Level of metabolic activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the different needs for a transport system?

A

1) metabolic demands of most multicellular animals are high, diffusion over long distances isnt sustainable to supply organism
2) SA:V ratio is smaller as multicellular organism gets bigger
3) molecules e.g. hormones/enzymes made in one place but needed in another
4) food is digested in 1 organ system but needs to be transported for every cell to use - respiration & cell metabolism
5) waste products of metabolism need to be removed from the cell & transported to excretory organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the features of an effective transport system?

A

1) A fluid/medium to carry nutrients, oxygen & wastes around the body e.g Blood
2) A pump to create pressure to push fluid around the body e.g. heart
3) Exchange surfaces that enables substances to enter/leave the blood where they’re needed e.g. capillaries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the features of an efficient transport system?

A

1) Tubes/vessels to carry the blood by mass flow
2) 2 circuits - 1 to pick up & 1 to deliver oxygen to the tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a single circulatory system?

A

One in which the blood flows through the heart once for each circuit of the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a double circulatory system?

A

One in which the blood flows through the heart twice for each circuit of the body of the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is an open circulatory system?

A

One in which the blood isnt held in vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a closed circulatory system?

A

One in which the blood is held in vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is an example of an animal with a single circulatory system?

A

Fish

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the features of the single circulatory system in fish?

A

Blood pressure drops as blood flows through the tiny capillaries of the gills
Blood has a low pressure as it flows towards the body - wont flow quickly
Limited rate at which oxygen & nutrients are delivered to respiring tissues & CO2 & urea removed
Sufficient for fish - not as metabolically active as mammals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is an endotherm?

A

An organism that maintains a constant body temperature (‘warm blooded’)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a poikilotherm?

A

An organism that cannot maintain a constant body temperature (‘cold blooded’)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is an example of an animal with a double circulatory system?

A

Mammals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the features of a double circulatory system?

A

Blood pressure isnt too high in the pulmonary circulation - may damage capillaries in the lungs
Heart can increase the blood pressure after its passed through the lungs - blood pressure higher & flows quicker
The systematic circulation can carry blood at high pressure than pulmonary circulation
Suitable for mammals - active & have high energy requirement (energy released from food in respiration)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the advantages of the single circulatory system?

A

Less complex & doesn’t require complex organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the disadvantages of the single circulatory system?

A

Low blood pressure - slow movement of blood
Low activity level of the organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the advantages of the double circulatory system?

A

Heart can pump blood further around the body
Higher blood pressure - blood flow quicker

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the disadvantages of the double circulatory system?

A

Requires complex organs & structures
Something goes wrong- affects whole organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is an example of an animal with an open circulatory system?

A

Insects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the features of an open circulatory system?

A

Blood fluid (haemolymph) circulates through the open body cavity (haemocoel) rather than being held within blood vessels
Transport medium is under low pressure
Comes into direct contact with tissues & cells
Exchange takes place between transport medium & cells
The transport medium returns to the heart through an open ended vessel
Some animals require the body to move to help circulate the blood
Larger & more active insects e.g. locusts have open ended tubes attached to the heart - direct blood to active parts of the body e.g wings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the features of the insect heart

A

muscular pumping organ like a heart
Long muscular tube that lies just under the dorsal surface of the body
Blood from the body enters the heart through pores (Ostia)
The heart then pumps the blood towards the head by peristalsis
At the forward end of the heart (nearest the head) the blood pores out of the body cavity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the disadvantages of the open circulatory system?

A

Blood pressure is low & blood flow is slow
Circulation of the blood may be affected by body movements/lack of

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What organisms have a double circulatory system?

A

All vertebrates (e.g. fish & mammals)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the features of the double circulatory system?

A

Larger animals have the blood entirely inside vessels
Separate fluid (tissue fluid) bathes the tissues & cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are the advantages of the double circulatory system?

A

Higher blood pressure, quicker blood flow
More rapid delivery of oxygen & nutrients
More rapid removal of CO2 & other wastes
Transport is independent of body movements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How does the heart work in fish?

A

The heart pumps blood into arteries which branch out into millions of capillaries. Substances e.g. glucose & oxygen diffuse from the blood into the capillaries & into body cells but the blood stays inside the blood vessels as it circulates. Veins take the blood back to the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are the main differences between the structure of arteries & veins?

A

Arteries - smaller lumen, thicker walls
Veins - larger lumen, thinner walls, valves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are the 5 types of blood vessel?

A

Arteries
Arterioles
Capillaries
Venules
Veins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the structure of the arteries?

A

The walls contain elastic fibres, smooth muscle (endothelium) & collagen

Elastic fibres - withstand the force of blood pumped out & stretch to take larger blood volume. Recoil to the original length in each contraction (can still feel pulse of blood)
Collagen - maintains limit at which it can stretch
Endothelium - smooth so blood flows easily over it

Small lumen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the function of the arteries?

A

Carry blood away from the heart & carry deoxygenated blood (except pulmonary & umbilical artery)
Carry blood at higher pressure than blood in the veins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the structure of the arterioles?

A

Walls contain less elastic fibres & more smooth muscle (endothelium)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the function of the arterioles?

A

Links arteries & capillaries
Have little pulse surge but can constrict/dilate to control flow of blood to individual organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is vasoconstriction?

A

Smooth muscle in the arterioles constricts & prevents blood flowing into the capillary bed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is vasodilation?

A

Smooth muscle in the arteriole wall relaxes so blood flows into the capillary bed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is the structure of the capillaries?

A

Small lumen - red blood cells have to travel in single file
Gaps between endothelial cells that make up the wall are large - substance exchange (exception in CNS)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is the function of capillaries?

A

Link arterioles with venules
Form an extensive network through all the bodily tissues
Carry oxygenated blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What are the adaptations of capillaries?

A

Large surface area - diffusion
Total cross sectional area of capillaries is always greater than arteriole supplying them - rate of blood flow falls
Single cell thick - diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is the structure of venules?

A

Have very thin walls with little smooth muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is the function of venules?

A

Link capillaries with veins
Several venules join to form a vein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is the structure of veins?

A

Lots of collagen & little elastic fibres, wide lumen & smooth endothelium (blood flows easily)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What is the function of veins?

A

Carry blood away from cells & towards the heart
Don’t have pulse - surges from the heart pumping are lost as blood passes through narrow capillaries
Low blood pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What are the 3 adaptations of veins?

A

One way valves - prevent back flow of blood
Many veins run between active muscles of the body e.g arms - when they contract they squeeze blood towards the heart
Breathing movements of the chest act as a pump - pressure changes & squeezing actions move blood of abdomen & chest towards the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Why do the veins have adaptations?

A

They contain blood that flows at a low pressure & the blood moves against gravity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

what are transport fluids & what is their function?

A

All substances needed by the cells must be in solution so that they can be absorbed through membranes
Blood carries chemicals around the body
Between blood vessels & the cells, the transport is done by tissue fluid
Excess tissue fluid is returned to the blood by lymph (role in immunity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What are the different components of blood?

A

RBC
WBC
Platelets
Plasma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What is the function of RBC?

A

Transports O2 & CO2 by haemoglobin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What is the function of WBC?

A

Plays a role in the immune system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What is the function of platelets?

A

Cell fragments that have a role in the clotting process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What is the function of plasma?

A

the liquid medium of blood which transports dissolved substances (O2,CO2,minerals,glucose, amino acids, hormones & plasma proteins)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What is tissue fluid?

A

Similar to blood plasma but doesn’t contain plasma proteins/most of the cells
Formed by plasma leaking from capillaries
Surrounds cells in the tissue & supplies them with O2 & nutrients
Waste products from cell metabolism are carried back to the capillaries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What is lymph?

A

very similar to tissue fluid but contains more WBC & collects in large quantities in the lymph nodes to fight infection
smallest lymph vessels are lymph capillaries. Valves in the lymph vessels stop lymph going backwards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

How does tissue fluid form?

A

The hydrostatic (forces fluid out) & oncotic pressure gradient draws water in by osmosis) control the movement of fluid to & from the capillaries
The fluid that leaves the blood consists of plasma with dissolved nutrients & O2, any larger molecules & cells remain in the capillary as they cant pass through the walls
The tissue fluid surrounds the cells, allowing exchange of gases & nutrients - exchange happens by diffusion, facilitated diffusion & active transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What is hydrostatic pressure?

A

The pressure that a fluid exerts when pushing against the sides of the container/vessel

55
Q

What is oncotic pressure?

A

The pressure created by the osmotic effects of the solutes

56
Q

How does fluid move through the vessel?

A

The hydrostatic pressure of the blood pushes fluid out the tissue
Oncotic pressure of the blood pulls water back into the blood
The hydrostatic pressure of the tissue pushes fluid into the capillaries
Oncotic pressure of the tissue fluid pulls water into the tissue fluid

57
Q

What are the different external structures of the mammalian heart?

A

Vena cava
Superior & inferior vena cava
Pulmonary artery & vein
Coronary artery
Aorta
Right & left atrium
Right & left ventricle

58
Q

What are the different internal features of the mammalian heart? (some external too)

A

Vena cava
Aorta
Semilunar valves
Right & left atrium
Right & left ventricle
Atrioventricular valves
Septum
Pulmonary artery & veins
Value tendons

59
Q

What is the structure of the heart?

A

Many parts of the heart contain cardiac muscle (firm, dark-red muscle)
Coronary artery lies across the surface of the heart - supplies oxygenated blood

60
Q

What happens if coronary arteries become restricted?

A

Blood flow to the heart can become restricted - can cause angina/myocardial infarction (heart attack)

61
Q

How many chambers does the heart have?

A

4

62
Q

What are the names of the 4 chambers of the heart?

A

Right atrium
Right ventricle
Left atrium
Left ventricle

63
Q

How does blood flow through the heart?

A

The atria receive blood from the major veins. Deoxygenated blood flows from the vena cava into the right atrium. Oxygenated blood flows from the pulmonary vein to the left atrium
From the atria, blood flows down the atrioventricular valves into the ventricles.
Deoxygenated blood leaving the right ventricle flows into the pulmonary artery leading to the lungs
Oxygenated blood leaves the left ventricle via the aorta.

64
Q

What are attached to the valves & what do they do?

A

Tendinous cords - prevent the valves turning inside out during ventricle wall contractions

65
Q

What is the septum?

A

A wall of muscle that separates the left & right sides of the heart
Keeps oxygenated & deoxygenated blood separate

66
Q

What is the function of the aorta?

A

Carries the blood to the main arteries that supply blood to all the body parts

67
Q

What is the function of the semilunar valves & where are they located?

A

Semilunar valves are at the base of the major arteries where they exit the heart
Prevent blood returning to the heart as the ventricles relax

68
Q

What is the blood pressure in the atrial wall & why?

A

Very thin - dont create much pressure

69
Q

What is the blood pressure like in the right ventricle & why?

A

Walls are thicker than the atrial walls so blood can be pumped out of the heart to the lungs
Doesn’t need high pressure as the blood travels a short distance & the alveoli are very delicate

70
Q

What is the blood pressure like in the left ventricle & why?

A

Walls 2-3x thicker than the right ventricle
Blood has to be pumped at a high enough pressure to overcome the resistance of the systematic circulation & go around the whole body

71
Q

What is the role of the heart?

A

To create pressure that pushes blood around the blood vessels

72
Q

What is the cardiac cycle?

A

The sequence of events in one full beat of the heart
- ventricular systole
- diastole
- atrial systole

73
Q

What happens during the cardiac cycle?

A

1) Both L & R ventricles pump together - contractions start at the apex of the heart (blood pushed towards arteries)
2) The muscular walls of all 4 chambers relax - elastic recoil causes the chambers to increase in volume (allows blood from veins to flow in)
3) Both L & R atria contract together - muscles is thin so pressure only slightly increases (helps blood push into ventricles & stretches their walls so they’re full of blood)

74
Q

What is the purpose of the valves?

A

Ensures blood flows in the correct direction as changes in blood pressure in chambers control opening & closing of the valves

75
Q

What happens at stage 1 of the cardiac cycle?

A

a) the Atrium starts to contract so the pressure increases
b) The pressure increase is relatively small as the atria have thin muscular walls)
c) This creates a small pressure increase in the ventricle as blood flows in

76
Q

What happens at stage 2 of the cardiac cycle?

A

a) The atrio-ventricular valve closes
b) the atrium relaxes & the ventricle starts to contract
c) when the pressure in the ventricle is higher than the atrium the AV valve is forced closed

77
Q

What happens at stage 3 of the cardiac cycle?

A

a) The ventricle contracts
b) the continued contraction of the thick muscular wall of the ventricle increases the pressure
c) small rise in atrial pressure due to the closed AV valve bulging into the atrium

78
Q

What happens at stage 4 of the cardiac cycle?

A

a) the semi-lunar valve opens due to pressure increasing in the ventricle than the aorta
b) as the semi-lunar valves open, blood flows into the aorta
c) pressure increases in the aorta

79
Q

What happens at stage 5 of the cardiac cycle?

A

a) the ventricle starts to relax
b) pressure in the ventricle starts to drop

80
Q

What happens at stage 6 of the cardiac cycle?

A

a) semi-lunar valves close when the pressure in the ventricle is below the aorta

81
Q

What happens at stage 7 of the cardiac cycle?

A

a) AV valve open as pressure in the ventricle decreases below the atrium
b) blood is flowing into the atrium causing a gradual rise in pressure that is released when the valve opens & blood flows into the ventricle

82
Q

What happens at stage 8 of the cardiac cycle?

A

a) the aorta wall recoil
b) when blood flows into the aorta the highly elastic walls stretch & expand
c) when blood flow slows, the elastic tissue recoils putting extra pressure on the blood (not active contraction)
d) ensures the continuation of blood flow from the heart during period when both atria & ventricles contract

83
Q

Does blood always flow from high to low pressure?

A

high to low

84
Q

What happens when blood flows from low to high pressure?

A

valves open

85
Q

what happens at low blood pressure?

A

closed valve

86
Q

What is cardiac output?

A

The volume of blood pumped by the heart per minute (measured in cm3 min-1)

87
Q

What is the equation for cardiac output?

A

Cardiac output = Heart rate x stroke volume

88
Q

What is the type of muscle found in the heart chamber walls?

A

cardiac muscle

89
Q

What is the process that creates pressure in the chamber walls?

A

systole

90
Q

Why is the cardiac muscle described as myogenic?

A

Means the cardiac muscle can contract without stimulation from the outside world

91
Q

Which part of the nervous system is the heart a part of?

A

The autonomic nervous system

92
Q

What is the autonomic nervous system?

A

The part of the nervous system that controls involuntary activity (e.g. heart activity, peristalsis, changes in size of the blood vessels).
consists of 2 parts

93
Q

What are the 2 parts that make up the autonomic nervous system & what do they do?

A

Parasympathetic nervous system (decreases heart rate)
Sympathetic nervous system (increases heart rate)

they both have opposite effects

94
Q

What are the 4 main parts that control the heartbeat?

A

The Sino-Atrial node (SAN)
The Atrioventricular node (AVN)
The Bundle of His
The Purkyne fibres/tissues

95
Q

What is the Sino-atrial node (SAN)

A

1) a small patch of tissue that acts as a pacemaker & generates electric activity
2) initiates a wave of excitation at regular intervals

96
Q

How do the atria contract?

A

1) the wave of excitation spreads quickly over the atrial walls - travels along the membranes of the muscle tissue
2) there is a band of non-conducting collagen tissue to prevent the electrical wave being passed directly from the atria to the ventricles
3) these waves are then passed from the SAN to the AVN & atria contract

97
Q

What is the name for when the atria contract?

A

atrial systole

98
Q

What are the purkyne fibres?

A

specialised conducting tissue

99
Q

How do the ventricles contract?

A

4) There is a short delay in the AVN where electrical activity reaches peak (ensures the atria empty)
5) AVN passes the electrical activity to the Bundle of His which is passed to the Purkyne fibres
6) The wave of excitation runs down into the ventricular septum & once it is at the base of the septum it spreads over the ventricular walls
7) As the excitation spreads upwards from the apex of the ventricles it causes the muscles to contract from the apex upwards
8) This pushes blood up towards the arteries at the top of the heart

100
Q

How is electrical activity of the heart monitored?

A

Electrocardiography

101
Q

Why are sensors placed on the skin?

A

To detect electrical activity from the heart

102
Q

What is depolarisation

A

Losing electrical charge

103
Q

What is repolarisation?

A

Regaining charge

104
Q

Does heart muscle depolarise or repolarise when contracting?

A

Depolarise

105
Q

Does the heart muscle depolarise or repolarise when relaxing

A

Repolarise

106
Q

What is the p wave in the ECG trace?

A

The wave detected by the contraction (depolarisation) of the atria

107
Q

What is the QRS complex in the ECG trace?

A

The wave caused by the contraction (depolarisation) of the ventricles

108
Q

What is the T wave in the ECG trace?

A

The wave caused by relaxation (repolarisation) of the ventricles
Diastole

109
Q

What is the calculation for heart rate?

A

HR = 60/time taken for one heartbeat (s)

110
Q

What is the normal resting heart rate?

A

60-100bpm

111
Q

What is a sinus rhythm ECG?

A

A normal ECG

112
Q

What is Tachycardia?

A

When heart rate is too rapid at rest (okay at exercise) -> HR > 100bpm
Shown in the ECG by the peaks being too close together

113
Q

What is Bradycardia?

A

When the heart rate is too slow at rest (normal in some people e.g. athletes)
Shown in the ECG by the peaks being too far apart

114
Q

What is a ectopic heartbeat?

A

When the heart beats too early followed by a pause
Common & requires no treatment + patient may feel heartbeat has been missed

115
Q

What is atrial fibrillation?

A

When the heartbeat is irregular (the p wave is not defined)
The atria lose their rhythm & don’t contract properly
Can result in chest pain, blood clots, stroke or death

116
Q

Why do we need haemoglobin?

A

1) the solubility of oxygen is low
2) If O2 was dissolved in the plasma there wouldnt be enough to supply the body
3) RBC has a red pigment (haemoglobin)
4) haemoglobin readily absorbed oxygen to transport around the body

117
Q

What is affinity?

A

A strong attraction

118
Q

What is the structure of haemoglobin?

A

1) Large protein with a quaternary structure
2) has 4 polypeptide chains (2 alpha, 2 beta)
3) each chain has iron-containing haem group that has a high affinity for oxygen
4) each molecules of human haemoglobin can carry 4 oxygen molecules

119
Q

How does haemoglobin transport of oxygen?

A

1) in lungs - o2 joins iron in the haemoglobin -> oxyhaemoglobin
2) reversible reaction (near body cells o2 leaves oxyhaemoglobin & turns back into haemoglobin)
3) o2 joins to haemoglobin -> association/loading
4) o2 leaves haemoglobin -> dissociation/unloading

120
Q

What is the relationship between the affinity of o2 & po2

A

Depends on the conditioning its in (partial pressure of o2)
The greater the concentration of dissolved o2 in cells -> higher partial pressure
As po2 increases, haemoglobin’s affinity for o2 also increases
A) o2 loads where there’s high po2
B) o2 unloads where there’s low po2

121
Q

What is the po2 & affinity like in the alveoli of the lungs?

A

High oxygen concentration
High po2
High affinity
O2 loads

122
Q

What is the po2 & affinity like in the respiring tissues?

A

Low oxygen concentration
Low po2
Low affinity
O2 unloads

123
Q

What is the role haemoglobin in CO2 transport?

A

1) carbon dioxide is released from respiring tissues
2) must be removed from these & transported by the blood to the lungs or excretion
3) there are 3 forms that co2 is transported in:
A) dissolved co2 (5% in the plasma)
B) hydrogen carbonate ions (70-90% HCO3- ions formed in blood but transported in plasma)
C) combined directly with the haemoglobin (10% forms carbaminohaemoglobin (co2 binds to the terminal amino group of haemoglobin molecule))

124
Q

How is CO2 transported by red blood cells?

A

1) CO2 diffuses into the RBC
2) CO2 is converted into carbonic acid by the carbonic anhydrase enzyme
3) Carbonic acid then dissociates to form H+ & Hydrogen carbonate ions
4) The hydrogen carbonate ions diffuse out of the RBC down a concentration gradient & combine with sodium ions in the plasma to form sodium hydrogen carbonate
5) Chloride shift happens (hydrogen carbonate ions are replaced with chloride ions which diffuse in from the plasma to maintain electrochemical neutrality in the cell
6) The H+ ions combine to form haemoglobinic acid (HHb) which enhances O2 release (Bohr effect) & also becomes a substrate for carboamino formation (CO2 binds to Hb) & has a buffering effect (prevents a drop in pH)
7) oxyhaemoglobin dissociates due to the low pH under the influence of H+ ions & oxygen is released into blood plasma

125
Q

What type of curve is produced in haemoglobin and how does this differ from a normal liquid?

A

Haemoglobin interacts with oxygen in a way that produces an S shaped dissociation curve whereas oxygen absorbed in a liquid is directly proportional to the oxygen tension in the surrounding air

126
Q

What happens in a oxygen dissociation curve

A

A) a slow increase due to relative difficulty absorbing the 1st o2 molecule
b) There is a steep increase due to increasing ease to absorb the 2nd, 3rd & 4th o2 molecule - haemoglobin changes shape (conformational change) after it has combined with the 1st o2 molecule

127
Q

What is the difference between foetal & adult haemoglobin & why is this important?

A

They both have very different affinities for O2

foetal has a higher affinity for O2 than adult as it is important the foetus gets O2 from its mother

128
Q

What happens to ensure a foetus gets sufficient oxygen?

A

at a low partial pressure in the placenta, foetal haemoglobin has a high affinity for o2 so o2 loads

at a low partial pressure in the placenta, adult haemoglobin has a low affinity for o2 so o2 unloads

129
Q

When there is low partial pressure of oxygen (in respiring tissues) is the oxygen saturation low or high & why?

A

low (haemoglobin has a low affinity for o2)

130
Q

When there is high partial pressure of oxygen (in lungs) is the oxygen saturation low or high & why?

A

high (haemoglobin has a high affinity for o2)

131
Q

What is the Bohr effect?

A

When haemoglobin is impacted due to more CO2 release (tissues are more active)

132
Q

What happens in the Bohr effect?

A

1) CO2 enters the RBC forming carbonic acid which dissociates into H+ ions
2) These H+ ions lower the pH of the cytoplasm -> more acidic
3) Change of pH affects the tertiary structure of proteins (including haemoglobin) so CO2 reduces haemoglobin’s affinity for O2
4) This leads to oxyhaemoglobin releasing O2 to tissues as it cant hold as much
5) Means that when more CO2 is present, haemoglobin becomes less saturated with O2 so the dissociation curve moves

133
Q

What happens at the lungs?

A

There is a low partial pressure of CO2
The dissociation curve shifts to the left
The affinity of haemoglobin for O2 increases
There is increased loading of O2

134
Q

What happens at the tissues?

A

There is a high partial pressure of CO2
The dissociation curve shifts to the right
The affinity of haemoglobin for O2 decreases
There is increased release of O2

A Level Biology (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions