3.1.2 Transport in Animals Flashcards
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
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
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
4
Q
factors that affect the need for a transport system
A
size
surface area:volume ratio
level of activity
body temperature
5
Q
basic components of a circulatory system
A
circulating fluid
pumping device
blood vessels
valves
exchange surface
circuits
6
Q
single circulatory system
A
blood passes through the heart once during one complete circulation of the body
7
Q
double circulatory system
A
blood passes through the heart twice during one complete circulation of the body
two circuits: pulmonary and systemic
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
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
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
11
Q
organims with closed circulatory system
A
fish, birds, mammals, amphibians
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
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
14
Q
organisms with open circulatory system
A
insects, molluses
15
Q
advantages of closed circulatory system
A
higher pressure of blood maintained
rapid flow of blood maintained
greater control of blood distribution
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)
17
Q
types of blood vessels
(5)
A
artery
arterioles
capillaries
veins
venules
18
Q
function of artery
A
transport blood away from the heart (usually at high pressure) to tissues
19
Q
function of arterioles
A
narrower blood vessels branched from arteries
transport blood from arteries into capillaries
20
Q
function of capillaries
A
responsible for the exchange of oxygen, nutrients, and waste products between the blood and the cells
21
Q
function of veins
A
transport blood to the heart (usually at low pressure)
22
Q
function of venules
A
narrower blood vessels
transports blood from capillaries to veins
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
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
25
tunica media - artery
**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
26
tunica intima - artery
**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**
27
lumen - artery
**narrow** - helps maintain blood pressure
28
structure of arterioles
**walls of 3 layers:** tunica adventita/externa, tunica media, tunica intima - less elastic tissue, more smooth muscle
**lumen**
29
muscular layer in arterioles
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
30
structure of capillary
very small lumen/diameter
wall: single layer of endothelial cells
31
lumen - capillary
**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
32
walls of capillary
**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
33
structure of veins
**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
34
tunica adventita - vein
thick layer
**collagen:** provides strength
**elastic fibres**
35
tunica media - vein
much thinner layer - no need, don't have to withstand high pressure
36
tunica intima - vein
endothelium, little connective tissue
37
large lumen - vein
**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
38
structure of venule
few or no elastic fibres
**large** lumen
39
when does tissue fluid formation occur
plasma leaks out through fenestrations of capillary to surround the cells of the body
40
why are there no proteins in tissue fluid
proteins are too large to pass through fenestrations in capillaries
41
function of tissue fluid
bathes cells of the body outside of circulatory system
exchange of substances between cells and the blood
42
hydrostatic pressure
the pressure exerted by a fluid
blood pressure inside the capillaries caused by fluid pushing against walls of the capillary
43
oncotic pressure
the net pressure of movement of fluid from tissue fluid into capillaries
the osmotic pressure exerted by plasma proteins within a blood vessel
44
arterial end of capillary
**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**
45
venous end of capillary
**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**
46
tissue fluid formation
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
47
tissue fluid reabsorption
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
48
functions of the lymph
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
49
what causes lymph movement
skeletal muscle contractions
respiratory pump
hydrostatic pressure
valves
smooth muscle in lymphatic vessels
50
what causes lymph movement
skeletal muscle contractions
respiratory pump
hydrostatic pressure
valves
smooth muscle in lymphatic vessels
51
importance of lymphatic drainage
plasma proteins need to be returned to heart
fluid returns to blood
prevents swelling
52
how does the loss of proteins in urine affect circulation of tissue fluid
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
constituents of blood
plasma
red blood cells (erythrocytes)
white blood cells (leukocytes)
platelets
54
constituents of tissue fluid
similar to plasma but no large proteins
white blood cells may be present - can squeeze through
no red blood cells
55
constituents of lymph
similar to tissue fluid but with more fat, more white blood cells, antibodies
56
formation of blood
stem cells in bone marrow
57
where is blood found
heart
blood vessels
58
where is tissue fluid found
bathing the cells
59
function of blood
transport of substances
defence against pathogens
60
differences in composition of tissue fluid and plasma
**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
four chambers of the mammalian heart
right ventricle - thick walled
right atrium - thin walled
left ventricle - thick walled
left atrium - thin walled
62
separation of chambers
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
valves in the heart
open: pressure of blood behind them > pressure in front of them
close: pressure of blood in front of them > pressure behind them
64
function of valves
keeping blood flow in the correct direction
stop it flowing backwards
maintain the correct pressure in the chambers
65
valve separating right atrium and right ventricle
atrioventricular valve (tricuspid valve)
66
valve separating right ventricle and pulmonary artery
pulmonary valve
67
valve separating left atrium and left ventricle
mitral valve (bicuspid valve)
68
valve separating left ventricle and aorta
aortic valve
69
blood vessels that bring blood to the heart
vena cava and pulmonary vein
70
blood vessels that take blood away from the heart
pulmonary artery and aorta
71
why and how does the heart receive blood
receives blood through coronary arteries for aerobic respiration
72
coronary arteries
supply cardiac muscle cells with nutrients
remove waste from cardiac muscle cells
73
structure of cardiac muscle tissue
multinucleate = multiple nuclei
step-like intercalated disc - gap junctions
many mitochondria - prevents fatigue by producing lots of ATP
74
myogenic
initiate its own contractions without the need for nervous stimulation
75
why is there a delay between contractions
allows the heart to refill with blood before next contraction
prevents oxygen debt = cardiac muscle fatigue prevented
76
diastole - relaxed phase, no contracting
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
atrial systole - atria contracting simultaneously
**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
ventricular systole - atria relaxed, ventricles contracting
**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
ventricular and atrial diastole
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
stenosis
heart valves become rigid
loss of flexibility causes heart to work harder to propel blood through valve
heart eventually weakens
81
heart rate
number of times the heart beats in one minute
82
stroke volume
the amount of blood pumped by each ventricle with each heartbeat
83
cardiac output
the volume of blood ejected from the ventricles into the arteries per minute
= stroke volume x heart rate
84
effect of exercise on cardiac output
(short term)
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
effect of exercise on cardiac output
(long term)
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
advantages of increased cardiac output
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
two nodes in the heart
sinoatrial node (SAN)
atrioventricular node (AVN)
88
accelerator nerve
acts on sinoatrial nerve to increase heart rate
89
vagus nerve
acts on sinoatrial node to decrease heart rate
90
sinoatrial node
specialised group of cardiac cells
initiate a wave of excitation which spreads across atria walls causing depolarisation - co-ordinated simultaneous contraction
91
atrioventricular node
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
bundle of His
modified cardiac fibres that run down the interventricular septum
fan out over the walls of the ventricles forming network of fibres = Purkyne fibres
93
Purkyne fibres
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
advantages of co-ordinating the heart beat
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
p wave
electrical activity during atrial systole
atrial depolaristion
96
qrs complex
electrical activity during ventricular systole
ventricular depolarisation
atrial repolarisation (obscured on ECG)
97
t wave
ventricular repolarisation
recovery of ventricular wall
98
q-t interval
contraction time - ventricles are contracting
99
t-p interval
filling time
ventricles are relaxed + filling with blood
100
why does the wave of excitation not spread down the ventricles after being sent out by the sinoatrial node
would cause ventricles and atria to contract simultaneously
atria and ventricles would not have maximum pumping effect - ventricles not completely full
101
bradycardia
slow heart rate
maybe caused by beta blockers, tranquilisers
causes blood clots
102
tachycardia
rapid heart rate
filling time reduced
treatment: beat blockers, relaxation therapy
103
atrial fibrillation
irregular, lost rhythm
atria contract more frequently than ventricles
risk of blood clot, stroke
104
ventricular fibrillation
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
ectopic heartbeat
heart beats too early, followed by a pause
extra beats out of the normal rhythm
106
partial pressure of gases
pressure exerted by a gas in a mixture of gases
directly related to the concentration of that gas in the mixture
107
role of haemoglobin
transport of oxygen
carbon dioxide transport
formation of hydrogen carbonate ions
the chloride shift
108
transport of oxygen by haemoglobin
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
carbon dioxide transport by haemoglobin
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
formation of hydrogen carbonate ions by haemoglobin
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
normal atmospheric pressure
760mmHg = sum of all major gases in the air
112
stages of oxygen dissociation curve
slow increase
steep increase
levels out
113
oxygen dissociation curve: slow increase
haem groups are found in the middle of haemoglobin, it is difficult for the first oxygen group to associate
114
oxygen dissociation curve: steep increase
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
oxygen dissociation curve: level out
once the haemoglobin contains 3 oxygen molecules, it becomes harder for the fourth molecule to associate
116
oxygen dissociation curve: where the partial pressure of oxygen is high
haemoglobin has a high affinity for oxygen, so has a high % saturation of oxygen (haemoglobin is loading oxygen)
117
oxygen dissociation curve: where the partial pressure of oxygen is low
haemoglobin has a low affinity for oxygen, so unloads oxygen and has a low % saturation of oxygen
118
foetal haemoglobin vs adult haemoglobin
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
myoglobin vs haemoglobin
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
ways carbon dioxide is transported away from respiring tissues
5% dissolves directly into blood plasma
85% transported in form of HCO3 - ions
10% combines with haemoglobin = carbaminohaemoglobin
121
formation of hydrogen carbonate ions
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
