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a-level biology > 3.1.2 Transport in Animals > Flashcards

3.1.2 Transport in Animals Flashcards

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1
Q

the reason why small simple organisms do not need a transport system

A

large SA: V ratio - short diffusion distance = can rely on simple diffusion of substances
small size - less cells = less active, lower metabolic rate = lower demand for oxygen and nutrients

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2
Q

the reason why multicellular organisms need a transport system

A

small SA: V ratio - diffusion distance too large to reach demands = cannot rely on simple diffusion
large size - many cells= more active, higher metabolic rate = higher demand for oxygen, glucose, removal of waste

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3
Q

large multicellular organisms need a transport system to:

A

transport minerals: oxygen, glucose, amino acids, fatty acids, glycerol
transport waste: carbon dioxide, urea
transport hormones, antibodies

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4
Q

factors that affect the need for a transport system

A

size
surface area:volume ratio
level of activity
body temperature

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5
Q

basic components of a circulatory system

A

circulating fluid
pumping device
blood vessels
valves
exchange surface
circuits

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6
Q

single circulatory system

A

blood passes through the heart once during one complete circulation of the body

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7
Q

double circulatory system

A

blood passes through the heart twice during one complete circulation of the body
two circuits: pulmonary and systemic

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8
Q

single circulatory system in a fish

A

deoxygenated blood is pumped by heart to the gills
gills - exchange surface of oxygen and carbon dioxide
oxygenated blood flows from gills to the rest of the body
blood travels through capillaries
blood returns to the heart
heart - 1 atrium, 1 ventricle

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9
Q

double circulatory system in mammals

A

deoxygenated blood in right side of the heart travels to lungs
alveoli - exchange surface for oxygen and carbon dioxide
oxygenated blood enters left side of the heart
oxygenated blood is pumped around the body
deoxygenated blood returns to right side of the heart

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10
Q

closed circulatory system

A

blood is fully enclosed within blood vessels at all times = blood pressure, rapid flow of blood can be maintained giving greater control over blood distribution

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11
Q

organims with closed circulatory system

A

fish, birds, mammals, amphibians

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12
Q

open circulatory system

A

fluid is not enclosed within blood vessels so it moves** slowly + at a low pressure** in cavity due to the movement of the organism
heart pumps haemolymph through short vessels into large cavity = harmocoel
haemolymph directly bathes tissues = enables diffusion
when the heart relaxes, haemolymph sucked back in via pores

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13
Q

ineffciency of open circulatory systems

A

ok for insects as they are small + have a seperate system for oxygen transport
blood loses pressure in body cavity
cannot regulate direction of blood flow

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14
Q

organisms with open circulatory system

A

insects, molluses

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15
Q

advantages of closed circulatory system

A

higher pressure of blood maintained
rapid flow of blood maintained
greater control of blood distribution

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16
Q

circulatory system in insects

A

one main blood vessel - the dorsal vessel
tubular heart in abdomen pumps haemolymph into the dorsal vessel
dorsal vessel delivers the haemolymph into the haemocoel (body cavity)
haemolymph surrounds the organs, re-enters the heart via ostia (one-way valves)

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17
Q

types of blood vessels
(5)

A

artery
arterioles
capillaries
veins
venules

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18
Q

function of artery

A

transport blood away from the heart (usually at high pressure) to tissues

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19
Q

function of arterioles

A

narrower blood vessels branched from arteries
transport blood from arteries into capillaries

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20
Q

function of capillaries

A

responsible for the exchange of oxygen, nutrients, and waste products between the blood and the cells

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21
Q

function of veins

A

transport blood to the heart (usually at low pressure)

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22
Q

function of venules

A

narrower blood vessels
transports blood from capillaries to veins

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23
Q

structure of arteries

A

thick walls: maintain + withstand high pressures
walls of 3 layers: tunica adventita/externa, tunica media, tunica intima
narrow lumen

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24
Q

tunica adventita - artery

A

elastic fibres:, elastin (fibrous protein), stretches to prevent bursting, recoils to propel blood + even out surges in blood pressure
collagen: fibrous protein, provides strength to withstand high pressure

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25
Q

tunica media - artery

A

elastic fibres: elastin (fibrous protein), stretches to prevent bursting, recoils to propel blood + even out flucuations in blood pressure
smooth muscle: vasoconstriction + vasodilation, strengthens blood vessel to withstand high pressures, enables artery to contract and narrow the lumen for reduced blood flow

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26
Q

tunica intima - artery

A

endothelium: lines the lumen, smooth lining to reduce friction and increase blood flow, folded and expand when artery stretches, impermeable
connective tissue
layer of elastic fibres

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27
Q

lumen - artery

A

narrow - helps maintain blood pressure

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28
Q

structure of arterioles

A

walls of 3 layers: tunica adventita/externa, tunica media, tunica intima - less elastic tissue, more smooth muscle
lumen

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29
Q

muscular layer in arterioles

A

allows them to contract and close their lumen to stop and regulate blood flow
contract and partially cut off blood flow to specific organs - allows more blood to reach priority muscles during exercise

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30
Q

structure of capillary

A

very small lumen/diameter
wall: single layer of endothelial cells

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31
Q

lumen - capillary

A

narrow: squeezes red blood cells against walls to improve transfer of oxygen, forces the blood to travel slowly = provides more time for diffusion to occur

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32
Q

walls of capillary

A

one cell thick: reduces the diffusion distance for oxygen and carbon dioxide between the blood and the tissues of the body
**have gaps “fenestrations”: **allow blood plasma to leak out and form tissue fluid
white blood cells: combat infection in affected tissues by squeezing through the intercellular junctions in capillary walls

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33
Q

structure of veins

A

thin wall: doesn’t need to withstand high pressure
walls of 3 layers: tunica adventita/externa, tunica media, tunica intima - less smooth muscle, elastic fibres
large/wide lumen:can accomadate large volumes of blood, less % blood in contact with walls = less resistance to flow = eases blood flow back to heart
valves: prevent backflow of blood

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34
Q

tunica adventita - vein

A

thick layer
collagen: provides strength
elastic fibres

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35
Q

tunica media - vein

A

much thinner layer - no need, don’t have to withstand high pressure

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36
Q

tunica intima - vein

A

endothelium, little connective tissue

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37
Q

large lumen - vein

A

eases blood flow back to heart as there’s less % of blood in contact with vein walls = less resistance to flow
reduces friction between the blood and the endothelial layer
blood flow is slower, but a larger lumen = volume of blood delivered per unit of time is equal

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38
Q

structure of venule

A

few or no elastic fibres
large lumen

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39
Q

when does tissue fluid formation occur

A

plasma leaks out through fenestrations of capillary to surround the cells of the body

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40
Q

why are there no proteins in tissue fluid

A

proteins are too large to pass through fenestrations in capillaries

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41
Q

function of tissue fluid

A

bathes cells of the body outside of circulatory system
exchange of substances between cells and the blood

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42
Q

hydrostatic pressure

A

the pressure exerted by a fluid
blood pressure inside the capillaries caused by fluid pushing against walls of the capillary

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43
Q

oncotic pressure

A

the net pressure of movement of fluid from tissue fluid into capillaries
the osmotic pressure exerted by plasma proteins within a blood vessel

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44
Q

arterial end of capillary

A

hydrostatic pressure is high = fluid forced out of capillary
proteins remain in the blood = too large to pass through fenestrations
increased protein content = water potential gradient (osmotic pressure) between capillary and tissue fluid
hydrostatic pressure > osmotic pressure = net movement of water is out of the capillaries into tissue fluid

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45
Q

venous end of capillary

A

hydrostatic pressure is reduced = furthe raway from the heart, slow blood flow
water potential gradient same as at arterial end
osmotic pressure > hydrostatic pressure = water flows back into capillary from tissue fluid
90% of the fluid lost at the arterial end is **reabsorbed **
other 10 % remains as tissue fluid then collected by lymph vessels

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46
Q

tissue fluid formation

A

blood arrives at arterial end - high hydrostatic pressure
net HP > OP = positive net filtration pressure - fluid leaving blood via fenestrations
fluid carries water, solutes, glucose to tissue cells
red blood cells + large plasma proteins = too large to pass through

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47
Q

tissue fluid reabsorption

A

occurs at venous end
net HP < OP = net filtration pressure is negative
oncotic pressure has not changed = plasma proteins remain in blood, hydrostatic pressure has decreased = fluid lost from blood
fluid is reabsorbed by osmosis

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48
Q

functions of the lymph

A

returns 10% of tissue fluid to blood
returns plasma proteins to blood
lacteals - allows fatty acids + glycerol to enter blood
prevents pathogens entering circulation
returns excess fluid to blood via subclavian vein

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49
Q

what causes lymph movement

A

skeletal muscle contractions
respiratory pump
hydrostatic pressure
valves
smooth muscle in lymphatic vessels

50
Q

what causes lymph movement

A

skeletal muscle contractions
respiratory pump
hydrostatic pressure
valves
smooth muscle in lymphatic vessels

51
Q

importance of lymphatic drainage

A

plasma proteins need to be returned to heart
fluid returns to blood
prevents swelling

52
Q

how does the loss of proteins in urine affect circulation of tissue fluid

A

fewer proteins in body = lower oncotic pressure
more tissue fluid accumulates, less is reabsorbed
reabsorbtion is reduced at venous end due to low oncotic pressure

53
Q

constituents of blood

A

plasma
red blood cells (erythrocytes)
white blood cells (leukocytes)
platelets

54
Q

constituents of tissue fluid

A

similar to plasma but no large proteins
white blood cells may be present - can squeeze through
no red blood cells

55
Q

constituents of lymph

A

similar to tissue fluid but with more fat, more white blood cells, antibodies

56
Q

formation of blood

A

stem cells in bone marrow

57
Q

where is blood found

A

heart
blood vessels

58
Q

where is tissue fluid found

A

bathing the cells

59
Q

function of blood

A

transport of substances
defence against pathogens

60
Q

differences in composition of tissue fluid and plasma

A

plasma:
higher concentration of glucose
higher concentration of glycerol and fatty acids
higher concentration of amino acids
higher concentration of plasma proteins
lower water potential
higher oxygen concentration
lower carbon dioxide concentration
tissue fluid:
higher concentration of the substances secreted by cells

61
Q

four chambers of the mammalian heart

A

right ventricle - thick walled
right atrium - thin walled
left ventricle - thick walled
left atrium - thin walled

62
Q

separation of chambers

A

sides of heart separated by wall of muscular tissue = septum - ensures blood does not mix
left and right atria = interatrial septum
left and right ventricles = interventricular septum

63
Q

valves in the heart

A

open: pressure of blood behind them > pressure in front of them
close: pressure of blood in front of them > pressure behind them

64
Q

function of valves

A

keeping blood flow in the correct direction
stop it flowing backwards
maintain the correct pressure in the chambers

65
Q

valve separating right atrium and right ventricle

A

atrioventricular valve (tricuspid valve)

66
Q

valve separating right ventricle and pulmonary artery

A

pulmonary valve

67
Q

valve separating left atrium and left ventricle

A

mitral valve (bicuspid valve)

68
Q

valve separating left ventricle and aorta

A

aortic valve

69
Q

blood vessels that bring blood to the heart

A

vena cava and pulmonary vein

70
Q

blood vessels that take blood away from the heart

A

pulmonary artery and aorta

71
Q

why and how does the heart receive blood

A

receives blood through coronary arteries for aerobic respiration

72
Q

coronary arteries

A

supply cardiac muscle cells with nutrients
remove waste from cardiac muscle cells

73
Q

structure of cardiac muscle tissue

A

multinucleate = multiple nuclei
step-like intercalated disc - gap junctions
many mitochondria - prevents fatigue by producing lots of ATP

74
Q

myogenic

A

initiate its own contractions without the need for nervous stimulation

75
Q

why is there a delay between contractions

A

allows the heart to refill with blood before next contraction
prevents oxygen debt = cardiac muscle fatigue prevented

76
Q

diastole - relaxed phase, no contracting

A

low-pressure blood enters atria
atria fill with blood = become distended
atrial pressure > ventricular pressure = bi/tricuspid valves open
blood flows into relaxed ventricles
semi-lunar valves shut = aortic pressure > ventricular pressure

77
Q

atrial systole - atria contracting simultaneously

A

atria pressure increases = more blood flows into ventricles
contraction of atria walls seals off vena cava + pulmonary vein = prevents backflow into veins
atria - thin walls: only need enough pressure to pump blood a short distance (atria to ventricles)

78
Q

ventricular systole - atria relaxed, ventricles contracting

A

ventricular pressure increases
ventricular pressure > aortic pressure = semi-lunar valves open
ventricular pressure > atria pressure = bi/tricuspid valves close, prevents backflow
blood expelled from ventricles through aorta and pulmonary artery

79
Q

ventricular and atrial diastole

A

high pressure develops in arteries = blood forced back towards ventricles
semi-lunar valves close to prevent backflow
atria then begin to fill again for another cycle

80
Q

stenosis

A

heart valves become rigid
loss of flexibility causes heart to work harder to propel blood through valve
heart eventually weakens

81
Q

heart rate

A

number of times the heart beats in one minute

82
Q

stroke volume

A

the amount of blood pumped by each ventricle with each heartbeat

83
Q

cardiac output

A

the volume of blood ejected from the ventricles into the arteries per minute
= stroke volume x heart rate

84
Q

effect of exercise on cardiac output
(short term)

A

cardiac output increases - extra demand for oxygen, glucose for more respiration = increased heart rate
volume of blood in heart increases = extra stretching of left ventricle wall - stronger contraction, stroke volume increases

85
Q

effect of exercise on cardiac output
(long term)

A

increases ventricular wall strethcing, stronger contractions cause muscle in left ventricle wall to become thicker
more blood is ejected per beat = takes less heart beats to deliver same cardiac output

86
Q

advantages of increased cardiac output

A

to deliver more blood to cells/organs/tissues
to deliver more oxygen/glucose/amino acids
to meet the need for a higher metabolic rate

87
Q

two nodes in the heart

A

sinoatrial node (SAN)
atrioventricular node (AVN)

88
Q

accelerator nerve

A

acts on sinoatrial nerve to increase heart rate

89
Q

vagus nerve

A

acts on sinoatrial node to decrease heart rate

90
Q

sinoatrial node

A

specialised group of cardiac cells
initiate a wave of excitation which spreads across atria walls causing depolarisation - co-ordinated simultaneous contraction

91
Q

atrioventricular node

A

near the base of the right atrium
delays the wave of excitation
provides a route for transmission of the wave from atria to ventricles
continuous with the bundle of His

92
Q

bundle of His

A

modified cardiac fibres that run down the interventricular septum
fan out over the walls of the ventricles forming network of fibres = Purkyne fibres

93
Q

Purkyne fibres

A

conducts wave of excitation to apex of ventricles
wave radiates upwards through ventricle walls causing depolarisation
cells contract from apex up - forces blood up and out of the heart

94
Q

advantages of co-ordinating the heart beat

A

ensures cells in atria contract at the same frequency and in synchrony
ensures ventricular systole is delayed before both ventricles contract in synchrony = maximum pumping effect

95
Q

p wave

A

electrical activity during atrial systole
atrial depolaristion

96
Q

qrs complex

A

electrical activity during ventricular systole
ventricular depolarisation
atrial repolarisation (obscured on ECG)

97
Q

t wave

A

ventricular repolarisation
recovery of ventricular wall

98
Q

q-t interval

A

contraction time - ventricles are contracting

99
Q

t-p interval

A

filling time
ventricles are relaxed + filling with blood

100
Q

why does the wave of excitation not spread down the ventricles after being sent out by the sinoatrial node

A

would cause ventricles and atria to contract simultaneously
atria and ventricles would not have maximum pumping effect - ventricles not completely full

101
Q

bradycardia

A

slow heart rate
maybe caused by beta blockers, tranquilisers
causes blood clots

102
Q

tachycardia

A

rapid heart rate
filling time reduced
treatment: beat blockers, relaxation therapy

103
Q

atrial fibrillation

A

irregular, lost rhythm
atria contract more frequently than ventricles
risk of blood clot, stroke

104
Q

ventricular fibrillation

A

electrical impulses are firing from multiple points in ventricles
rhythm has been lost
uncoordinated, weak heartbeats
lack of oxygen to heart
defibrillation restarts heart

105
Q

ectopic heartbeat

A

heart beats too early, followed by a pause
extra beats out of the normal rhythm

106
Q

partial pressure of gases

A

pressure exerted by a gas in a mixture of gases
directly related to the concentration of that gas in the mixture

107
Q

role of haemoglobin

A

transport of oxygen
carbon dioxide transport
formation of hydrogen carbonate ions
the chloride shift

108
Q

transport of oxygen by haemoglobin

A

oxygen is bound to Hb in erythrocytes
1 molecule Hb = four haem groups = each haem group binds to one oxygen molecule
Hb can carry eight oxygen atoms
oxygen binds to Hb= oxyhaemoglobin (Hb4O2)
binding of first oxygen molecule = a conformational change in structure of Hb molecule =easier for the next oxygen molecule to bind (cooperative binding)

109
Q

carbon dioxide transport by haemoglobin

A

carbon dioxide produced during respiration diffuses from tissues into blood
small percentage of carbon dioxide dissolves directly in the blood plasma & is transported in solution
carbon dioxide can bind to haemoglobin, forming carbaminohaemoglobin
larger percentage of carbon dioxide is transported in the form of hydrogen carbonate ions (HCO 3-)

110
Q

formation of hydrogen carbonate ions by haemoglobin

A

carbon dioxide diffuses from the plasma into red blood cells
inside red blood cells, CO2 + H2O ⇌ H2CO3

RBCs contain carbonic anhydrase = catalyses the reaction between CO2 + H2O

plasma contains little carbonic anhydrase = H2CO3 forms slowly in plasma
Carbonic acid dissociates readily into H+ and HCO3- ions
H2CO3 ⇌ HCO 3– + H+

H+ can combine with Hb, forming haemoglobinic acid = preventing the H+ ions from lowering the pH of the red blood cell
Hb acts as a buffer

111
Q

normal atmospheric pressure

A

760mmHg = sum of all major gases in the air

112
Q

stages of oxygen dissociation curve

A

slow increase
steep increase
levels out

113
Q

oxygen dissociation curve: slow increase

A

haem groups are found in the middle of haemoglobin, it is difficult for the first oxygen group to associate

114
Q

oxygen dissociation curve: steep increase

A

once the first oxygen molecule associates, there is a slight change in the shape of haemoglobin
this makes it easier for more oxygen molecules to diffuse and associate with haemoglobin

115
Q

oxygen dissociation curve: level out

A

once the haemoglobin contains 3 oxygen molecules, it becomes harder for the fourth molecule to associate

116
Q

oxygen dissociation curve: where the partial pressure of oxygen is high

A

haemoglobin has a high affinity for oxygen, so has a high % saturation of oxygen (haemoglobin is loading oxygen)

117
Q

oxygen dissociation curve: where the partial pressure of oxygen is low

A

haemoglobin has a low affinity for oxygen, so unloads oxygen and has a low % saturation of oxygen

118
Q

foetal haemoglobin vs adult haemoglobin

A

the foetal Hb curve shifted to the left
foetal Hb has a higher oxygen affinity = higher oxygen saturation
it can always load oxygen from maternal Hb in the placenta, through villi

119
Q

myoglobin vs haemoglobin

A

myoglobin curve shifted to the left
myoglobin has a high affinity for oxygen = it will only dissociate and unload oxygen when oxygen levels are very low

120
Q

ways carbon dioxide is transported away from respiring tissues

A

5% dissolves directly into blood plasma
85% transported in form of HCO3 - ions
10% combines with haemoglobin = carbaminohaemoglobin

121
Q

formation of hydrogen carbonate ions

A

carbon dioxide from blood plasma diffuses into red blood cells and combines with water = carbonic acid (catalysed by carbonic anhydrase)
carbonic acid dissociates into hydrogen carbonate ions and protons

a-level biology (26 decks)

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