3.1.2 - Transport in Animals Flashcards
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
2
Q
Single circulatory system
A
Blood flows through the heart and travels around the whole body once before returning
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
4
Q
Pulmonary circuit
A
Pick up oxygen
5
Q
Systemic circuit
A
Deliver oxygen
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
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
8
Q
Tissues in artery
A
Folded endothelium
Elastic fibres
Smooth muscle
Collagen fibres
9
Q
Function of artery
A
Carry blood away from heart to tissue
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
11
Q
Function of smooth muscle
A
Contracts and relaxes to change diameter of lum
12
Q
Function of collagen fibres
A
Provide structural support
13
Q
Function of arterioles
A
Link arteries and capillaries
14
Q
Tissues in arteriole
A
More smooth muscle
Less elastin
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
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
17
Q
Function of capillary
A
Enable exchange of material between the blood and tissue fluid
18
Q
Structure of capillary
A
One layer of endothelium cells
Similar diameter to RBC
Leaky epithelium
No tissues
19
Q
Structure of venule
A
Endothelium
Smooth muscle
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
21
Q
Function of venules
A
Link capillaries with veins
Several venules join to form a vein
22
Q
Function of endothelium
A
Allows blood to flow easily (reduces friction to blood flow)
23
Q
Structure of veins
A
Larger lumen - allow lower pressure, reduces resistance to flow Endothelium Elastic fibres Smooth muscle Collagen fibres
24
Q
Function of veins
A
Transport deoxygenated blood at a lower pressure back to heart
Enable blood flow in only one direction - valves
25
What type of valves do veins have
The majority have one way valves
26
One-way valves
Flaps of the inner lining of the vein
| If blood starts to flow backwards (gravity), valves close
27
Why does being immobile increase the risk of a blood clot
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
28
Open circulation
Fluid isn’t always contained within vessels
29
How does open circulation work in animals that don’t have a pump
It relies on movements of the body
30
How does open circulation work in insects
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
31
Open circulation in larger, more active insects
They have open ended tubes attached to the heart directing the blood to more active parts of the body
32
Disadvantages of open circulatory system
Low bp and blood flow is slow
Circulation of blood is affected by body movement or lack of
Oxygenated and deoxygenated blood will mix
33
Closed circulation
Blood stays entirely inside vessels - gives it high pressure
It is a separate fluid, tissue fluid, that bathes the tissues and cells
34
Advantages of a closed circulatory system
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
35
What does the right side of the heart do
Pump deoxygenated blood to the lungs to be oxygenated
36
What does the left side of the heart do
Pump oxygenated blood to the rest of the body
37
External features of the heart
Cardiac muscle
Coronary arteries
Ventricles
Atria
38
Role of the coronary arteries
Deliver oxygenated blood from the heart. If these arteries become constricted this can cause angina or myocardial infarction
39
Bicuspid
Left Atrioventricular valve
40
Tricuspid (try before you buy)
Right atrioventricular valve
41
Pathway of blood from vena cavae
Vena cava —> right atrium —> tricuspid —> right ventricle —> pulmonary artery —> lung —> pulmonary vein —> left atrium —> bicuspid —> left ventricle —> semilunar valve —> aorta —> rest of body
42
Function of vena cava
Deoxygenated blood from the body flows through the vena cava into the right atrium
43
Aorta
Oxygenated blood is pumped from the left ventricle through the aorta and to the body
44
Pulmonary vein
Oxygenated blood from the lungs flow through the pulmonary vein into the left atrium
45
Pulmonary artery
Deoxygenated blood passes from the right ventricle to the pulmonary artery to the lungs
46
Atrioventricular valves
These valves sit between atria and ventricles and prevent blood travelling back from ventricles to atria during ventricular systole
47
Tendinous cords
These prevent the valves from turning inside out when the ventricle walls contract
48
Semilunar valves
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
49
Ventricular septum
A wall of muscle separating the ventricles from each other
50
Thickness of walls in the heart
Atria - thin
Right ventricle - thicker than atria but thinner than left ventricle
Left ventricle - v. thick (2-3x thicker than right ventricle)
51
Pressure in atria
Low - only needs to push blood to ventricles
52
Pressure in right ventricle
Medium - only needs to pump to lungs (nearby). Alveoli could also be damaged by high blood pressure
53
Pressure in left ventricle
Highest - blood needs to be pumped to the whole body and needs sufficient pressure to overcome the resistance of the systemic circulation
54
Cardiac muscle structure
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
55
What do cross-bridges ensure
That cardiac muscle can produce a squeezing action rather than a simple reduction in length
56
What is blood composed of
Erythrocytes
Platelets
Leukocytes
Plasma
57
Plasma
```
Composed of dissolved substances:
Oxygen
Carbon dioxide
Glucose
Minerals
Amino acids
Hormones
Antibodies
Plasma proteins (albumin)
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58
Tissue fluid
Fluid that surrounds all cells and tissues. Between tissue fluid and cells that exchange of substances occurs
59
What does tissue fluid contain
Plasma and dissolved substances
Neutrophils
Few proteins
60
Why doesn’t tissue fluid have the same things in it as blood
Capillaries have small pores and not everything can fit through due to the size, therefore tissue fluid has less components than blood
61
Hydrostatic pressure
This is the pressure that a fluid exerts when pushing against the sides of a vessel.
62
When is hydrostatic pressure highest
The more fluid and the faster it is travelling will lead to a higher hydrostatic pressure
63
Oncotic pressure
Pressure that solutes (e.g. plasma proteins) have when they draw water in by osmosis
64
Why does oncotic pressure draw fluid from the tissue fluid into the capillaries
The capillaries contain large solutes
65
Formation of tissue fluid
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
Why does tissue fluid return to the blood
Hydrostatic pressure lower at venous end and oncotic pressure is higher due to plasma proteins
Fluid returns to capillary at venous end
67
Role of lymph
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
Lymph nodes
Swellings found at intervals along the lymphatic system which have an important part to play in the immune response
69
Cells found in lymph
Lymphocytes
70
Hydrostatic pressure in blood plasma
High
71
Hydrostatic pressure in tissue fluid and lymph
Low
72
Oncotic pressure in blood plasma
More negative
73
Oncotic pressure in tissue fluid and lymph
Less negative
74
Cardiac cycle
Atrial systole —> ventricular systole —> diastole
75
Diastole
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
Atrioventricular valves in diastole
Open
77
Semi lunar valves in diastole
Shut
78
Atrial systole
Atria contract together
Ventricles are relaxed
Small increase in atrial pressure to push blood to ventricles
Ventricles stretch as they fill
79
Atrioventricular valves in atrial systole
Open due to pressure gradient
80
Semilunar valves in atrial systole
Shut
81
Ventricular systole
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
Atrioventricular valves in ventricular systole
Shut
83
Semilunar valves in ventricular systole
Open
84
When do the atrioventricular valves open
Diastole - pressure in ventricles drop below pressure in atria
Blood flowing from atria to ventricles force valves open
85
When do the atrioventricular valves close
Ventricular systole - pressure in the ventricles rises above pressure in atria due to contraction
86
When do the semilunar valves open
Ventricular systole - when ventricular pressure rises above atrial pressure
87
When do the semilunar valves close
Diastole - ventricular pressure drops below the pressure in the major arteries
88
Where is the pressure highest in the blood vessels
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Aorta
Artery
Arteriole
Capillary
Venule
Vein
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89
Why does blood pressure fluctuate in the aorta
Due to rhythmical contractions of cardiac muscle in the left ventricle
The troughs are caused by relaxation
90
Why does pressure drop the further from the heart
The total cross-sectional area of the blood vessels further away from the heart gets larger as does the volume
Resistance to flow
91
Why is heart muscle myogenic
It can initiate its own contraction
92
What happens when the contractions of the chambers are not synchronised
This could cause inefficient pumping (fibrillation) so the heart needs a mechanism that coordinates heart contraction
93
Initiation and control of the heartbeat
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
Why does the AVN delay the wave of excitation
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
Why do the ventricles contract from the base upwards
So the blood can be pushed up towards the major arteries
96
ECG
Electrocardiograms - monitor the electrical activity of the heart
97
What can ECG traces indicate
When part of the heart muscle is not healthy and therefore can be used to be diagnosed to diagnose heart problems
98
How do ECG’s work
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
Parts of ECG traces
P wave
QRS complex
T wave
100
What do the P waves show
Atrial stimulation
101
What does the QRS complex show
Ventricular stimulation
102
What does T waves show
Diastole
103
Tachycardia
High heart rate
104
Bradycardia
Slow heart rate
105
Atrial fibrillation
No clear P waves
| Atria beating more frequently than ventricles
106
Ectopic heart beat
Extra ventricular systole
| Patient feels as if a heart beat has been missed
107
The haem group has a high affinity for ...
Oxygen
108
Partial pressure
Relative pressure a gas contributes to a mixture of gases
109
Transport of oxygen
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
When does haemoglobin dissociate with oxygen
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
Why is there low saturation of haemoglobin at low oxygen tensions
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
What happens when O2 tension rises
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
Why does fetal haemoglobin have a higher affinity than adult haemoglobin
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
What happens when O2 tension in placenta is low
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
How does artery wall adapted to maintain pressure
Smooth muscle constricts to narrow lumen
| Recoil pushes blood and maintains small lumen
116
How is CO2 transported around the body
5% - dissolved in plasma
10% - combines with haemoglobin (carbominohaemoglobin)
85% - transported in hydrogencarbonate ions
117
Formation of hydrogen carbonate ions
CO2 and H2O (carbonic anhydrase) —> carbonic acid
118
What happens to HCO3- after they diffuse out of RBCs and dissolves to be carried into lungs
Chloride shift to maintain neutral charge
119
Haemoglobinic acid
Formed when further H+ are taken out of solution by associating with haemoglobin
120
What happens when pH drops in the RBC
Haemoglobin molecules change shape slightly and dissociate more readily from O2
121
Why does increased CO2 reduce affinity of haemoglobin for O2
CO2 converts to HCO3-
Releases H+, lowers pH of cytoplasm
Alters tertiary structure of haemoglobin and reduces affinity
122
Bohr effect
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
Bohr shift
Refers to the fact that O2 dissociation curve shifts down and to the right as CO2 conc increases
124
Lymph
Excess tissue fluid that is not returned to the blood vessel
Contains less oxygen and more fatty acids
125
What causes the ‘lub dub’ sound
Closing of the AV valves
126
How do blood vessels maintain pressure
Narrow folded lumen in artery
Elastic fibres recoil
Smooth muscle contracts to constrict vessels
127
How do blood vessels withstand pressure
Collagen provides structural support
| Elastic fibres stretch
128
Why do we form adult haemoglobin
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
What happens to H+ ions after H2CO3 dissociates
H+ ions build up in RBC, pH decreases
Affects 3’ structure
Affinity for O2 decreased
Oxyhaemoglobin dissociates into Hb and O2
130
Haemoglobinic acid
Unsaturated Hb binds with H+
| Restores pH
131
HbO8
Saturated haemoglobin
4 haem groups -> each bind to an O2 molecule
Releases 4 O2 —> taken to plasma then respiring tissues
132
Disadvantage of haemoglobin not having membrane bound organelles
Limited life span (cannot undergo mitosis)
Limited respiration
No protein synthesis
133
Why don’t erythrocytes use any of the oxygen it is transporting
Erythrocytes lack mitochondria so do not respire aerobically
Moved by mass flow so needs less ATP for metabolic processes
134
Why does blood off load more oxygen to actively respiring tissues than to resting tissues
More CO2
Lowered affinity of Hb for O2
Dissociation of carbonic acid
More oxygen released at same pO2
135
Calculating cardiac output
Heart rate * stroke volume
136
How do vessels and arteries carry fluids
Mass flow
137
Why do animals need specialised transport systems
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
Functions of the blood
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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
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Maintenance of steady body temp
Acts as a buffer
