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OCR A level Biology > 3.1.2 - Transport in Animals > Flashcards

3.1.2 - Transport in Animals Flashcards

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1
Q

Features of a good transport system

A

Fluid - to carry nutrients, O2 and waste products (blood)
Pump - create pressure to push fluid around body (heart)
Exchange surface - to allow substances to leave and enter the transport system (capillaries)
Tubes or vessels - to carry fluid by mass flow
Two circuits

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2
Q

Single circulatory system

A

Blood flows through the heart and travels around the whole body once before returning

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3
Q

Double circulatory system

A

Involves two separate circulations
Blood is pumped from the heart to lungs and then returns
Blood then flows through the heart and is pumped out to travel all around the body before returning

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4
Q

Pulmonary circuit

A

Pick up oxygen

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5
Q

Systemic circuit

A

Deliver oxygen

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6
Q

Why is a single circulatory system less effective

A

As blood flows through gill capillaries, overall pressure decreases
Speed of flow decreases
Blood flowing to body will have a lower pressure and flow slower

Rate at which O2 and nutrients are delivered to respiring tissue and waste removed is limited

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7
Q

Why is blood pumped to the lungs at a low pressure in a double circulatory system

A

As not to damage the capillaries in the lungs

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8
Q

Tissues in artery

A

Folded endothelium
Elastic fibres
Smooth muscle
Collagen fibres

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9
Q

Function of artery

A

Carry blood away from heart to tissue

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10
Q

Function of elastic fibres

A

Composed of elastin and provides flexibility

Recoil artery wall to maintain pressure and even out surges to give a continuous flow

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11
Q

Function of smooth muscle

A

Contracts and relaxes to change diameter of lum

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12
Q

Function of collagen fibres

A

Provide structural support

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13
Q

Function of arterioles

A

Link arteries and capillaries

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14
Q

Tissues in arteriole

A

More smooth muscle

Less elastin

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15
Q

Vasoconstriction

A

When the arteriole is constricted and blood cannot enter the capillary network so is diverted to core of body
Less heat is lost from the skin

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16
Q

Vasodilation

A

When the smooth muscle in the wall of an arteriole is relaxed, blood flows through into the capillary bed. More heat can be lost from the skin

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17
Q

Function of capillary

A

Enable exchange of material between the blood and tissue fluid

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18
Q

Structure of capillary

A

One layer of endothelium cells
Similar diameter to RBC
Leaky epithelium
No tissues

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19
Q

Structure of venule

A

Endothelium

Smooth muscle

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20
Q

Adaptation of capillaries

A

Larger surface area - diffusion is faster
Slow movement of blood though them (one RBC at a time) means more time for exchange of materials
Walls are single endothelial cell thick - short diffusion pathway

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21
Q

Function of venules

A

Link capillaries with veins

Several venules join to form a vein

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22
Q

Function of endothelium

A

Allows blood to flow easily (reduces friction to blood flow)

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23
Q

Structure of veins

A 
Larger lumen - allow lower pressure, reduces resistance to flow 
Endothelium 
Elastic fibres 
Smooth muscle
Collagen fibres
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24
Q

Function of veins

A

Transport deoxygenated blood at a lower pressure back to heart
Enable blood flow in only one direction - valves

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25
Q

What type of valves do veins have

A

The majority have one way valves

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26
Q

One-way valves

A

Flaps of the inner lining of the vein

If blood starts to flow backwards (gravity), valves close

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27
Q

Why does being immobile increase the risk of a blood clot

A

Many of the bigger veins run between big, active muscles in the body (arms, legs)
When the muscles contract they squeeze veins, forcing blood towards the heart

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28
Q

Open circulation

A

Fluid isn’t always contained within vessels

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29
Q

How does open circulation work in animals that don’t have a pump

A

It relies on movements of the body

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30
Q

How does open circulation work in insects

A

They have muscular pumping organs - a long tube that lies under the dorsal surface of the body
Blood enters the near through pores called ostia
The heart then pumps the blood toward the heart by peristalsis. Blood then pours out into the body cavity

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31
Q

Open circulation in larger, more active insects

A

They have open ended tubes attached to the heart directing the blood to more active parts of the body

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32
Q

Disadvantages of open circulatory system

A

Low bp and blood flow is slow
Circulation of blood is affected by body movement or lack of
Oxygenated and deoxygenated blood will mix

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33
Q

Closed circulation

A

Blood stays entirely inside vessels - gives it high pressure
It is a separate fluid, tissue fluid, that bathes the tissues and cells

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34
Q

Advantages of a closed circulatory system

A

High pressure so blood flows more rapidly
More rapid delivery of oxygen and nutrients
More rapid removal of carbon dioxide and other waste
Transport is independent of body movement

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35
Q

What does the right side of the heart do

A

Pump deoxygenated blood to the lungs to be oxygenated

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36
Q

What does the left side of the heart do

A

Pump oxygenated blood to the rest of the body

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37
Q

External features of the heart

A

Cardiac muscle
Coronary arteries
Ventricles
Atria

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38
Q

Role of the coronary arteries

A

Deliver oxygenated blood from the heart. If these arteries become constricted this can cause angina or myocardial infarction

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39
Q

Bicuspid

A

Left Atrioventricular valve

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40
Q

Tricuspid (try before you buy)

A

Right atrioventricular valve

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41
Q

Pathway of blood from vena cavae

A

Vena cava —> right atrium —> tricuspid —> right ventricle —> pulmonary artery —> lung —> pulmonary vein —> left atrium —> bicuspid —> left ventricle —> semilunar valve —> aorta —> rest of body

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42
Q

Function of vena cava

A

Deoxygenated blood from the body flows through the vena cava into the right atrium

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43
Q

Aorta

A

Oxygenated blood is pumped from the left ventricle through the aorta and to the body

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44
Q

Pulmonary vein

A

Oxygenated blood from the lungs flow through the pulmonary vein into the left atrium

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45
Q

Pulmonary artery

A

Deoxygenated blood passes from the right ventricle to the pulmonary artery to the lungs

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46
Q

Atrioventricular valves

A

These valves sit between atria and ventricles and prevent blood travelling back from ventricles to atria during ventricular systole

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47
Q

Tendinous cords

A

These prevent the valves from turning inside out when the ventricle walls contract

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48
Q

Semilunar valves

A

These are at the base of the pulmonary artery and aorta and prevent blood travelling back to the ventricles when it’s pumped out and the ventricles are relaxed

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49
Q

Ventricular septum

A

A wall of muscle separating the ventricles from each other

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50
Q

Thickness of walls in the heart

A

Atria - thin
Right ventricle - thicker than atria but thinner than left ventricle
Left ventricle - v. thick (2-3x thicker than right ventricle)

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51
Q

Pressure in atria

A

Low - only needs to push blood to ventricles

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52
Q

Pressure in right ventricle

A

Medium - only needs to pump to lungs (nearby). Alveoli could also be damaged by high blood pressure

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53
Q

Pressure in left ventricle

A

Highest - blood needs to be pumped to the whole body and needs sufficient pressure to overcome the resistance of the systemic circulation

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54
Q

Cardiac muscle structure

A

Consists of fibres that branch producing cross-bridges that help to spread the stimulus around the heart
Lot of mitochondria between myofibrils so supply energy for contraction

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55
Q

What do cross-bridges ensure

A

That cardiac muscle can produce a squeezing action rather than a simple reduction in length

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56
Q

What is blood composed of

A

Erythrocytes
Platelets
Leukocytes
Plasma

57
Q

Plasma

A 
Composed of dissolved substances: 
Oxygen 
Carbon dioxide 
Glucose 
Minerals 
Amino acids 
Hormones 
Antibodies 
Plasma proteins (albumin)
58
Q

Tissue fluid

A

Fluid that surrounds all cells and tissues. Between tissue fluid and cells that exchange of substances occurs

59
Q

What does tissue fluid contain

A

Plasma and dissolved substances
Neutrophils
Few proteins

60
Q

Why doesn’t tissue fluid have the same things in it as blood

A

Capillaries have small pores and not everything can fit through due to the size, therefore tissue fluid has less components than blood

61
Q

Hydrostatic pressure

A

This is the pressure that a fluid exerts when pushing against the sides of a vessel.

62
Q

When is hydrostatic pressure highest

A

The more fluid and the faster it is travelling will lead to a higher hydrostatic pressure

63
Q

Oncotic pressure

A

Pressure that solutes (e.g. plasma proteins) have when they draw water in by osmosis

64
Q

Why does oncotic pressure draw fluid from the tissue fluid into the capillaries

A

The capillaries contain large solutes

65
Q

Formation of tissue fluid

A

Hydrostatic pressure (caused by the heart) is high at the arteriole end
Greater than oncotic pressure
Leaky capillary wall allows plasma and some dissolved substances in but not RBC’s, proteins and some WBC’s (too large)
Tissue fluid surrounds body cells so exchange of gases and nutrients can occur across the plasma membrane (diffusion, facilitated diffusion and active transport)

66
Q

Why does tissue fluid return to the blood

A

Hydrostatic pressure lower at venous end and oncotic pressure is higher due to plasma proteins
Fluid returns to capillary at venous end

67
Q

Role of lymph

A

Drains excess tissue fluid out of the tissues. Lymph system rejoins blood circulation in the subclavian vein in the chest so this fluid is eventually all returned to the blood

68
Q

Lymph nodes

A

Swellings found at intervals along the lymphatic system which have an important part to play in the immune response

69
Q

Cells found in lymph

A

Lymphocytes

70
Q

Hydrostatic pressure in blood plasma

A

High

71
Q

Hydrostatic pressure in tissue fluid and lymph

A

Low

72
Q

Oncotic pressure in blood plasma

A

More negative

73
Q

Oncotic pressure in tissue fluid and lymph

A

Less negative

74
Q

Cardiac cycle

A

Atrial systole —> ventricular systole —> diastole

75
Q

Diastole

A

Muscular walls of all chambers are relaxed.
Elastic recoil causes chambers to increase in volume (lower pressure)
So blood flows into atria then ventricles (gravity)

76
Q

Atrioventricular valves in diastole

A

Open

77
Q

Semi lunar valves in diastole

A

Shut

78
Q

Atrial systole

A

Atria contract together
Ventricles are relaxed
Small increase in atrial pressure to push blood to ventricles
Ventricles stretch as they fill

79
Q

Atrioventricular valves in atrial systole

A

Open due to pressure gradient

80
Q

Semilunar valves in atrial systole

A

Shut

81
Q

Ventricular systole

A

Atria relax
Ventricles contract simultaneously
Contraction starts at apex of heart to push blood upwards
Huge increase in pressure forcing blood into aorta and pulmonary artery

82
Q

Atrioventricular valves in ventricular systole

A

Shut

83
Q

Semilunar valves in ventricular systole

A

Open

84
Q

When do the atrioventricular valves open

A

Diastole - pressure in ventricles drop below pressure in atria
Blood flowing from atria to ventricles force valves open

85
Q

When do the atrioventricular valves close

A

Ventricular systole - pressure in the ventricles rises above pressure in atria due to contraction

86
Q

When do the semilunar valves open

A

Ventricular systole - when ventricular pressure rises above atrial pressure

87
Q

When do the semilunar valves close

A

Diastole - ventricular pressure drops below the pressure in the major arteries

88
Q

Where is the pressure highest in the blood vessels

A 
Aorta
Artery 
Arteriole 
Capillary 
Venule
Vein
89
Q

Why does blood pressure fluctuate in the aorta

A

Due to rhythmical contractions of cardiac muscle in the left ventricle
The troughs are caused by relaxation

90
Q

Why does pressure drop the further from the heart

A

The total cross-sectional area of the blood vessels further away from the heart gets larger as does the volume
Resistance to flow

91
Q

Why is heart muscle myogenic

A

It can initiate its own contraction

92
Q

What happens when the contractions of the chambers are not synchronised

A

This could cause inefficient pumping (fibrillation) so the heart needs a mechanism that coordinates heart contraction

93
Q

Initiation and control of the heartbeat

A

SAN (found at the top of the right atrium) - initiates a wave of excitation
Wave of excitation quickly spreads over walls of both atria (travels quicker on left, atria contract simultaneously - atrial systole)
Wave of excitation passes through AVN, delays impulse
Carried away from the AVN, down the bundle of His and down the purkyne fibres
Spreads out over walls of ventricles to apex

94
Q

Why does the AVN delay the wave of excitation

A

Allow the atria to finish contacting so the blood can fill the ventricles before they begin to contract
Maximising amount of blood pumped out

95
Q

Why do the ventricles contract from the base upwards

A

So the blood can be pushed up towards the major arteries

96
Q

ECG

A

Electrocardiograms - monitor the electrical activity of the heart

97
Q

What can ECG traces indicate

A

When part of the heart muscle is not healthy and therefore can be used to be diagnosed to diagnose heart problems

98
Q

How do ECG’s work

A

Attaching a number of sensors to the skin. The sensors picks up electrical excitation created by the heart and convert this into a trace

99
Q

Parts of ECG traces

A

P wave
QRS complex
T wave

100
Q

What do the P waves show

A

Atrial stimulation

101
Q

What does the QRS complex show

A

Ventricular stimulation

102
Q

What does T waves show

A

Diastole

103
Q

Tachycardia

A

High heart rate

104
Q

Bradycardia

A

Slow heart rate

105
Q

Atrial fibrillation

A

No clear P waves

Atria beating more frequently than ventricles

106
Q

Ectopic heart beat

A

Extra ventricular systole

Patient feels as if a heart beat has been missed

107
Q

The haem group has a high affinity for …

A

Oxygen

108
Q

Partial pressure

A

Relative pressure a gas contributes to a mixture of gases

109
Q

Transport of oxygen

A

Hb has a high affinity for O2 and binds reversibly with oxygen to give oxyhaemoglobin
Dissociates when the pO2 is low e.g. respiring tissues

110
Q

When does haemoglobin dissociate with oxygen

A

When the partial pressure of oxygen is low. Oxygen then dissolves in plasma and moves out of the capillaries as tissue fluid
RBC’s cannot leave capillaries

111
Q

Why is there low saturation of haemoglobin at low oxygen tensions

A

When haemoglobin isn’t bound to O2 haem groups in centre of molecules
More difficult for the O2 molecule to reach the haem group

112
Q

What happens when O2 tension rises

A

Diffusion gradient in haemoglobin increases
Eventually O2 molecule enters and associates with haem group
Causes conformational change, allowing haemoglobin to associate with three more O2 molecules easier (positive cooperativity)
Curve levels off as haemoglobin reaches 100% saturation

113
Q

Why does fetal haemoglobin have a higher affinity than adult haemoglobin

A

It must be able to associate with O2 in an environment where the oxygen tension is low enough to make adult haemoglobin release O2

114
Q

What happens when O2 tension in placenta is low

A

Fetal haemoglobin binds to oxygen from surrounding fluid
Refuces O2 tension in placenta, more O2 diffuses from the mothers blood fluid into the placenta
Reduces O2 within mother’s blood, making maternal haemoglobin dissociate

115
Q

How does artery wall adapted to maintain pressure

A

Smooth muscle constricts to narrow lumen

Recoil pushes blood and maintains small lumen

116
Q

How is CO2 transported around the body

A

5% - dissolved in plasma
10% - combines with haemoglobin (carbominohaemoglobin)
85% - transported in hydrogencarbonate ions

117
Q

Formation of hydrogen carbonate ions

A

CO2 and H2O (carbonic anhydrase) —> carbonic acid

118
Q

What happens to HCO3- after they diffuse out of RBCs and dissolves to be carried into lungs

A

Chloride shift to maintain neutral charge

119
Q

Haemoglobinic acid

A

Formed when further H+ are taken out of solution by associating with haemoglobin

120
Q

What happens when pH drops in the RBC

A

Haemoglobin molecules change shape slightly and dissociate more readily from O2

121
Q

Why does increased CO2 reduce affinity of haemoglobin for O2

A

CO2 converts to HCO3-
Releases H+, lowers pH of cytoplasm
Alters tertiary structure of haemoglobin and reduces affinity

122
Q

Bohr effect

A

Increases CO2 conc. reduces haemoglobin affinity for O2
Actively repairing tissues produce more CO2 so more O2 is needed
More carbonic acid, more H+ in cytoplasm

123
Q

Bohr shift

A

Refers to the fact that O2 dissociation curve shifts down and to the right as CO2 conc increases

124
Q

Lymph

A

Excess tissue fluid that is not returned to the blood vessel
Contains less oxygen and more fatty acids

125
Q

What causes the ‘lub dub’ sound

A

Closing of the AV valves

126
Q

How do blood vessels maintain pressure

A

Narrow folded lumen in artery
Elastic fibres recoil
Smooth muscle contracts to constrict vessels

127
Q

How do blood vessels withstand pressure

A

Collagen provides structural support

Elastic fibres stretch

128
Q

Why do we form adult haemoglobin

A

So the conc. gradient is maintained if the baby has a child

Fetal haemoglobin will not readily dissociate to release O2 for actively respiring tissues

129
Q

What happens to H+ ions after H2CO3 dissociates

A

H+ ions build up in RBC, pH decreases
Affects 3’ structure
Affinity for O2 decreased
Oxyhaemoglobin dissociates into Hb and O2

130
Q

Haemoglobinic acid

A

Unsaturated Hb binds with H+

Restores pH

131
Q

HbO8

A

Saturated haemoglobin
4 haem groups -> each bind to an O2 molecule
Releases 4 O2 —> taken to plasma then respiring tissues

132
Q

Disadvantage of haemoglobin not having membrane bound organelles

A

Limited life span (cannot undergo mitosis)
Limited respiration
No protein synthesis

133
Q

Why don’t erythrocytes use any of the oxygen it is transporting

A

Erythrocytes lack mitochondria so do not respire aerobically
Moved by mass flow so needs less ATP for metabolic processes

134
Q

Why does blood off load more oxygen to actively respiring tissues than to resting tissues

A

More CO2
Lowered affinity of Hb for O2
Dissociation of carbonic acid
More oxygen released at same pO2

135
Q

Calculating cardiac output

A

Heart rate * stroke volume

136
Q

How do vessels and arteries carry fluids

A

Mass flow

137
Q

Why do animals need specialised transport systems

A

Metabolic demands
SA:V
Hormones/ enzymes made in one place and required in another
Waste products of metabolism need to be removed and transported to excretory systems
Food digested needs to be transported to each cell for respiration

138
Q

Functions of the blood

A 
Transport of:
Oxygen to and CO2 from respiring cells
Digested food from the small intestine
Nitrogenous waste products from the cells to the excretory system
Chemical messenger (hormones)
Platelets to damaged areas 
Cells and antibodies in immune response

Maintenance of steady body temp
Acts as a buffer

OCR A level Biology (25 decks)

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