mammalian transport Flashcards
1
Q
Why Do Multicellular Organisms Need Transport Systems?
A
Specialised exchange surfaces have been developed in organisms (e.g. alveoli in lungs), linked by a transport system (e.g. circulation), which carries substances to all parts of the body, e.g. O2 & nutrients and removes waste products, e.g. CO2 and urea.
2
Q
what factors affect the need for an animal’s transport system
A
- size
- activity
- surface area to volume ratio
3
Q
why is size an important factor for an animal’s transport system?
A
Larger animals have cells and tissues deep in the body
They distance is therefore too great to supply these cells with O2 and nutrients by diffusion from the outside.
O2 and nutrients will be used up by the outer layer of cells.
Diffusion would be too slow.
4
Q
why is activity an important factor for an animal’s transport system?
A
If an animal is very metabolically active more energy is needed.
More O2 is required to release energy from food by respiration.
Cell required more O2 and nutrients and require removal of more CO2 and waste products from the body
Diffusion is too slow to achieve this.
More energy is also required if the organisms keeps itself warm e.g. mammals
5
Q
why is SA:VR an important factor for an animal’s transport system?
A
Affected by size and shape
Small animals and thin, flat organisms have a large SA:V ratio. Exchange/diffusion can occur over the surface of their bodies.
As the organism increases in size the SA:V ratio decreases and the distance for diffusion is too great to supply enough O2 and nutrients to all cells.
6
Q
why is transport system used?
A
To be able to transport oxygen and nutrients to tissues/ remove excess carbon dioxide. it allows them to transport these quickly and in sufficient quantities. Specialised SA is needed for gaseous exchange
7
Q
what are the features needed for an efficient transport system?
A
- a fluid or medium to carry nutrients/oxygen
- pump to create pressure to push fluid around body
- exchange surfaces to enable oxygen and nutrients to enter and leave the blood
- tubes and vessels
- two circuits
8
Q
what happens in an open circulatory system?
A
blood is not always in the vessels. It circulates through the body cavity, directly bathing cells.
9
Q
why is an open system sufficient for a locust?
A
- They are small so blood does not have to travel far.
- They do not rely on blood to transport O2 or CO2.
- They have a separate transport system for this e.g. tracheae deliver air to the respiratory organs.
10
Q
How do locust circulate blood around their body to their tissues and cells?
A
- Blood is always maintained inside VESSELS and there is a HEART which pumps the BLOOD at higher PRESSURE
- There is a separate FLUID (TISSE FLUID) which enables the HEART to pump.
11
Q
what happens in a closed circulatory system?
A
the blood is always maintained in the vessels
12
Q
Why is an open circulation not sufficient to meet a fishes needs?
A
- They are LARGER organisms, and more ACTIVE, and rely on BLOOD to transport O2 and CO2
- An open circulation is not sufficient because BLOOD is at a very low PRESSURE and the FLOW is very slow.
- Therefore MUSCLES would not be supplied with enough BLOOD, and many other body parts would not receive enough OXYGEN & NURIENTS
13
Q
How do fish circulate blood around the body to their tissues and cells?
A
- Blood is always maintained inside VESSELS and there is a HEART which pumps the BLOOD at higher PRESSURE
- There is a separate FLUID (TISSE FLUID) which enables the HEART to pump.
14
Q
What happens in a single circulatory system?
A
the blood passes through the heart once on each circuit of the body
e.g. fish: heart → arteries → gills → veins → body tissues → veins → heart
15
Q
why do fish only need a single circulatory system?
A
- They are not as active as mammals and do not maintain their body temperature.
- Therefore they need less energy.
- Their single system delivers O2 and nutrients quickly enough to meet their needs.
16
Q
What happens in a double circulatory system?
A
the blood passes through the heart twice on each circuit of the body
17
Q
what are the two types of circulation in mammals?
A
systemic and pulmonary
18
Q
What is systemic circulation? pressure?
A
carries oxygen & nutrients around the body to the tissues
(higher pressure)
19
Q
What is pulmonary circulation? pressure?
A
carries blood to the lungs to pick up oxygen.
20
Q
what are the advantages of a double circulation?
A
An efficient circulatory system will deliver oxygen & nutrients quickly to the parts of the body where they are needed. The blood can be made to flow more quickly by increasing the blood pressure created by the heart.
21
Q
compare the transport systems of fish and mammals? SINGLE VS DOUBLE
A
Single: BP is reduced as blood flows through the tiny capillaries in the gills. Therefore is will not flow fast to the rest of the body.
LIMITS RATE OF DELIVERY
Double: BP is increased by the heart AFTER passing through the lungs.
Therefore blood flows more quickly to the body tissues.
This brings good supplies of both nutrients & oxygen.
22
Q
What is the basic structure of the heart?
A
- 2 pumps, side by side, left & right
- 4 chambers, 2 upper atria & 2 lower ventricles
23
Q
what side of the heart contains oxygenated blood?
A
left
24
Q
what side of the heart contains deoxygenated blood?
A
right
25
what chambers of the heart do arteries carry blood away from?
ventricles
26
what chambers of the heart do veins return blood from the heart to?
atria
27
why do the atrium have thinner muscular walls than ventricles?
only need to contract and create enough pressure to push blood a short distance to ventricles.
28
Why is the muscular wall of the left ventricle thicker than the right ventricle?
left needs to contract to produce a greater pressure to pump blood further – to body cells
Right only needs to contract to produce enough pressure to pump blood to the lungs which are closer
29
what are the advantages of having a double circulatory system?
- separation of oxygenated and deoxygenated blood
- More efficient/rapid supply of oxygen to body cells
- Maintains high blood pressure to body cells
- Allows a lower blood pressure to be supplied to the lungs (alveoli) to prevent them from getting damaged
30
what is the structure in regards to the blood supply to the heart?
Heart muscle needs its own blood supply – arteries branch off from aorta to form the coronary arteries which run through heart muscle, close to outer surface.
31
How do the heart valves work?
They only open one way – whether they are opened or closed depends on the relative pressure on either side.
32
if there is a high pressure, what happens to the valve?
it is forced open
33
if there is a low pressure, what happens to the valve?
it is forced closed
34
why does the heart need valves?
prevent back flow of blood
35
What is the purpose of the septum in the heart?
to separate the two sides of the heart, left side contains oxygenated blood whereas the right side contains deoxygenated blood.
36
what are the names of the atrio-ventricular valves? where are they located?
between each atrium and ventricle.
left side - bicuspid
right side - tricuspid
37
what is the name of the valve located in the aorta and pulmonary artery?
semilunar
38
How are the A-V valves attached?
A-V Valves are attached to ventricles by tendons to prevent valves inverting when ventricles contract
39
what do arteries do?
carry blood away from the heart
40
what do the veins do?
carry blood back to the heart
41
what is the function of the coronary artery?
to supply oxygen-rich blood to the heart muscle
42
what is systole in the cardiac cycle?
- Blood enters the left and right atria
- Pressure in the atria increases
- Bicuspid and tricuspid valves open slightly
- Blood starts to enter ventricles
43
what is the atrial systole stage of the cardiac cycle?
- Walls of the atria contract
- Bicuspid and tricuspid valves open fully
- Blood from the atria is forced into the ventricles
44
what is the stage of ventricular systole in the cardiac cycle?
- Ventricles contract
- Blood is forced into the pulmonary artery and the aorta
- Semi-lunar valves open
- Atrio-ventricular valves closed
45
what is the final stage of the cardiac cycle (diastole)?
- Blood pressure in the arteries is greater than in the ventricles
- Semi-lunar valves close to prevent backflow of blood into the ventricles
46
what happens at stage A?
At A - increasing ventricular pressure from systole causes a-v valves to close
47
what happens at stage B?
At B - increasing ventricular pressure from systole causes s-l valves to open
48
what happens at stage C?
At C - reducing ventricular pressure from diastole causes s-l valves to close
49
what happens at stage D?
At D - decreasing ventricular pressure from diastole causes a-v valves to open
50
What is the sinoatrial node?
small patch of tissue that sends out waves of electrical excitation at regular intervals to initiate contractions, it is the pacemaker.
51
what is the atrioventricular node?
- another node at the top of the septum separating the 2 ventricles
– this tissue picks up the wave of excitation and conducts it to a specialised conducting tissue called the PURKYNE TISSUE.
52
what is the purine fibres?
This tissue runs down the septum to the base and allows the wave of excitation to spread up the walls of the ventricles.
53
what is the process of the contraction of atria?
Sino atrial node fires, generating a wave of excitation which spread through atria causing them to contract.
The wave of excitation quickly spreads over the walls of both atria, travelling along the membranes of the muscle tissue and causing the cardiac muscle cells to contract.
54
what happens when the wave of excitation spreads?
it can't spread directly so it is picked up by the atrioventricular node.
55
what happens when the AVN picks up the wave of excitation?
the wave of excitation is delayed at the AVN, which allows time for the atria to finish contracting & force the blood to flow into the ventricles before they begin to contract.
56
What happens after the delay at the AVN?
After the delay, the wave of excitation is carried away from the AVN & down the Purkyne tissue which is located in the interventricular septum.
57
after the the wave of excitation passes down the purkyne tissue, what happens?
The wave then spreads upwards from the base of the septum (apex) causing the muscles to contract.
i.e. the ventricles contract from the base upwards, pushing the blood up to the major arteries.
58
what does an ECG show?
The electrical activity of the heart is monitored using an electrocardiogram (ECG).
This involves attaching sensors to the skin which pick up the electrical excitation created by the heart and converts it to a trace.
59
what is It called when the heart is beating irregularly?
arrhythmia
60
what is It called when the heart is beating too slowly?
Bradycardia
61
what is It called when the heart is beating too fast?
tachycardia
62
what is It called when the heart is not coordinated and what does it show?
fibrillation - AF indicated by small and unclear P waves
63
what does the ECG show on a heart attack?
indicated by elevation of the ST section
AKA: myocardial infarction
64
what is hypertrophy and how is it shown on an ECG?
if the heart has enlarged/increased muscle thickness
by a deep S wave
65
what else can a ECG show?
ECG can also show if the SAN or Purkyne tissue is not conducting electrical activity properly
66
what is the tunica intima made of in the artery?
made of squamous epithelial cells resting on a thin layer of elastic fibres
67
what is the tunica media made of?
contains elastic fibres, smooth muscle and some collagen fibres
68
what is the tunica external made of?
contains collagen fibres & some elastic fibres
69
what is the difference between the artery and vein tunica intima?
thinner than that of the artery and made of squamous epithelial cells
70
what is the composition of plasma?
- Mostly water
- Dissolved salts
- Hormones
- Waste products – urea, ammonia
- Organic molecules – glucose, amino acids
- Plasma proteins
71
what are the cells that blood contains?
red and white blood cells
72
what is the function of the red blood cells biconcave disc?
- A flat cell, indented on both faces
Large surface area. For rapid diffusion of oxygen and carbon dioxide
73
what is the reason for anulceatec red blood cells?
- No nucleus or organelles (respiration is anaerobic)
- To provide a large internal volume
to hold the maximum volume of haemoglobin
74
what is the size of the red blood cells?
Very small (7μm)
- haemoglobin is never far from cell plasma membrane so short diffusion pathway for oxygen
75
what area has high oxygen concentrations?
In blood vessels in the lungs
Haemoglobin becomes saturated and picks up many molecules of oxygen
76
what are has low oxygen concentrations?
In blood vessels in active tissues – muscle
Haemoglobin gives up any oxygen it is carrying (delivering the oxygen to the muscle)
77
what are the two types of wbc?
6000 per cubic mm
phagocytes and lymphocytes
78
what is the role of the phagocyte?
destroys invading microorganisms by phagocytosis (engulf)
79
what is the role of the lymphocyte?
produces antibodies and destroys infected cells.
80
properties of the lymphocytes
- Cytoplasm is not granular
- Nucleus is round, large and fills up almost all of the cell
81
what does the presence of carbonic anhydrase do for the abc?
Catalyses formation of carbonic acid, i.e. Reaction of CO2 with water (CO2 + H2O H2CO3-);
carbonic acid forms hydrogen carbonate ions;
in which form most is carried.
82
what is tissue fluid?
This surrounds body cells in the tissues and organs.Therefore exchange of gases & nutrients can occur across cell surface membrane – diffusion & facilitated
This is plasma that has passed out of the capillaries into the inter-cellular spaces WITHOUT red blood cells, platelets, most WBC and large plasma proteins
83
What regulates the amount of fluid movement?
- blood pressure (hydrostatic)
- osmotic pressure (due to water potential)
84
at the arterial end of the capillary, what happens?
- Blood pressure is high due to the contraction of muscle of the left ventricle of the heart
- which forces fluid OUT of the capillary
- There is also hydrostatic pressure in tissue fluid, which tends to push fluid back INTO the capillaries
- As a result, overall there will be a HIGH HP forcing water and dissolved molecules OUT of the capillary through the tiny gaps in the capillary walls.
85
what is the second part of the arterial end of the capillary?
- Plasma proteins remain in the capillaries as they are too large to pass through the gaps in the capillary wall.
- Therefore the water potential (solute potential) is LOWER in the blood of the capillary than in the tissue fluid
- There will be a SMALL osmotic pressure attempting to move water INTO the blood, by osmosis, down a water potential gradient.
86
what is the overall effect of the arterial end of the capillary?
- Higher hydrostatic pressure in blood vessel in blood vessel, pushing fluid, etc OUT
- Lower osmotic pressure in blood vessel, bringing fluid, etc IN
- HP is greater than osmotic pressure
Therefore - Fluid & dissolved solutes leave the capillary, at arterial end
87
what happens at the end of the venous capillary?
- Blood pressure is much lower here and there is still a small hydrostatic pressure exerted by the tissue fluid
- Since large plasma proteins remain in the blood in the capillary, lowering the water potential
- the water potential is now lower in the blood of the capillary than in the tissue fluid
- As a result, there will be a HIGHER osmotic pressure attempting to move water INTO the blood
88
what is the overall effect at the venous end of the capillary?
- No/ Very small difference in hydrostatic pressure across blood vessel
- Higher osmotic pressure in blood vessel
Fluids & dissolved solutes return to the capillary at venous end
89
what does fluids and dissolved solutes do to help?
This enables water and dissolved waste materials that have left the cells to return to back the blood.
90
what is oedema?
If the protein concentration and rate of loss from plasma are not in balance with the concentration and rate of loss from tissue fluid, there can be a build up of tissue fluid
91
why does tissue fluid build for oedema?
- Tissue fluid builds up because there is less protein in the diet, therefore LESS dissolved plasma proteins
- And therefore the water potential in the capillaries is higher
- Therefore less water is able to move back into the capillary down the water potential gradient.
92
what happens to the rest of the fluid that doesn't return to the capillary?
Around 90% of tissue fluid returns to the capillary at the venous end of the capillary.
The other 10% is known as `lymph’ and is returned in lymph vessels to the venous system in the chest cavity (also known as lymphatics)
93
what is the difference between tissue fluid and lymph?
- Lymph contains lymphocytes *
- Lymph is contained in vessels, tissue fluid is not
- Lymph has a higher concentration of fats, proteins & carbon dioxide
- Lymph has a lower concentration of glucose, a.a. & oxygen
94
What happens in a lymph vessel?
- lymph vessels are blind-ending vessels
- tissue fluid flows into the vessel through a valve in the vessel wall
- the valves prevent fluid moving out of the vessel
- lymph is returned to the venous system
95
what is the movement of lymph within the lymph vessel?
- Small lymphatics join to form bigger vessels
- Contraction of muscles around vessels
help push lymph along
- Smooth muscle in wall of lymph vessel
helps push lymph along
- Valves prevent backflow of lymph
96
What is the lymphatic system?
- lymph vessels are found throughout the body
- lymph rejoins venous system In the left and right subclavian veins
97
what does the lymphatic system contain and what do they do?
lymph nodes
- Found at intervals along lymph vessels
- Protect against disease
- Some contain white blood cells which remove pathogens while others make antibodies
98
what is the name of red blood cells?
erythrocytes
99
when haemoglobin takes up oxygen what is it called?
Oxyhaemoglobin, which is a reversible reaction
100
how is oxygen taken up in the lungs?
- The oxygen diffuses into the blood plasma and then enters the red blood cells where it is taken up by the haemoglobin.
- This takes the oxygen out of solution and so maintains the diffusion gradient for continued diffusion of more oxygen into the RBC.
101
how does releasing oxygen work in the lungs?
- The ability of haemoglobin to take up and release oxygen depends on the concentration of oxygen in the surrounding tissues, which is measured by the relative pressure that it contributes to a mixture of gases.
- This is called the partial pressure or pO2.
- It is also called the oxygen tension and is measured in units of pressure (kPa).
102
what is the shape of the Oxygen haemoglobin dissociation curve?
an s-shape/sigmoid
103
Is the percentage saturation of haemoglobin with oxygen high or low when the partial pressure of oxygen is low?
Very low - Hb is combined with only a very little oxygen
104
What is the likely percentage saturation of haemoglobin in the lungs?
e.g. if ppO2 = 12 kPa,
% saturation is very high – 96-98%,
i.e. it is combined with large amounts of oxygen
105
What happens to the percentage saturation of haemoglobin as the partial pressure of oxygen decreases?
it decreases
106
How does oxyhaemoglobin respond as blood flows through tissues that are actively respiring and using up a lot of oxygen?
It releases the oxygen which diffuses out of the RBC to the muscle cells.
107
Where is oxygen required?
In the mitochondria of the respiring cells; required for respiration - final electron acceptor
108
at high partial pressure of oxygen...
in the lungs, oxygen is picked up.
109
when the partial pressure of oxygen is decreased?
oxyhaemoglobin dissociates and oxygen is released to the tissues.
110
what is the partial pressure when a foetus obtains its oxygen?
low
111
how is foetal blood different from adult blood?
It has a greater affinity for oxygen which enables it to pick up the oxygen that the adult haemoglobin has released and results in the curve being shifted to the LEFT.
112
what does an increase in co2 do to the curve and what is it called?
An increase in the carbon dioxide concentration shifts the curve to the RIGHT.
BOHR SHIFT
112
What does transport of co2 do?
It enables additional OXYGEN to be delivered to muscle tissues when metabolic activity increases.
113
What is the effect of increasing the partial pressure of carbon dioxide on % saturation of haemoglobin with oxygen?
It causes haemoglobin to release its oxygen even more readily than it would do otherwise.
114
What is the advantage of this relationship between O2 and CO2?
More oxygen than usual is released from the blood when it travels through tissues that are respiring fast
115
What process can continue to occur in transport of co2?
aerobic respiration
116
what does the majority of co2 do?
The majority of carbon dioxide (85%) produced by tissues combines with water in the presence of the enzyme carbonic anhydrase, to form carbonic acid.
This dissociates into hydrogen ions (H+) and hydrogencarbonate ions (HCO3-).
117
what do the hydrogencarbonate ions do?
Most of the hydrogencarbonate ions diffuse out of the red blood cell into the blood plasma, where they are carried away in solution.
118
What happens to co2 in aqueous solutions?
Some carbon dioxide doesn’t dissociate but remains as carbon dioxide molecules. These dissolve into the blood plasma about 5% of the total co2 is carried in this form
119
How does CO2 transportation occur in combination with the haemoglobin molecules?
- A little carbon dioxide (about 10%) diffuses into red blood cells but instead of undergoing the reaction catalysed by carbonic anhydrase, it combines directly with the amine group (-NH2)of some of the haemoglobin molecules.
- This forms a compound called
carbamino haemoglobin.
120
what is the equation for the combination with Hb molecules?
CO2 + Hb ⇌ carbaminohaemoglobin
121
What happens when the blood reaches the lungs in co2 transport?
The reactions go in reverse –
The CO2 conc in alveoli is lower than in blood, therefore it diffuses from the blood to the alveoli.
This stimulates the CO2 of the carbamino – haemoglobin to leave the RBC.
Hydrogencarbonate ions and hydrogen ions recombine to form CO2 and the haemoglobin is free to re-associate with O2 and take it around the body, etc.
122
what is the process of transporting co2 (1)?
- CO2 diffuses from the respiring tissue through the capillary wall and plasma into the red blood cell.
- Inside the cell the enzyme carbonic anhydrase catalyses the conversion of carbon dioxide and water into carbonic acid.
- The hydrogen ions released by the carbonic acid destabilise the oxyhaemoglobin, causing it to release its oxygen molecules.
123
what is the process of transporting co2 (2)?
- The O2 diffuses into the tissues, and the Hb takes up the hydrogen ions forming HHb
- The accumulating hydrogen carbonate ions diffuse out of the red blood cell leaving the inside of the cell with a net positive charge.
- To maintain the charge balance, chloride ions diffuse into the cell.
This is called the chloride shift.
124
What does the chloride shift maintain?
electroneutrality
125
where is the pigment myoglobin found?
in high concentrations in the muscles of large diving birds and mammals where it functions as an oxygen store
126
what is myglobin?
Myoglobin is a respiratory pigment found in vertebrate muscle where it functions as an oxygen store; unlike haemoglobin, this molecule consists of a single polypeptide chain with one haem group and displays a higher affinity for oxygen than the haemoglobin molecule
127
what is the difference between myglobin and haemoglobin?
Myoglobin has a higher affinity for oxygen than haemoglobin and therefore removes oxygen from this molecule; myoglobin stores the loaded oxygen and releases it to active muscle tissue
128
what occurs during strenuous exercise in terms of oxygen?
During strenuous exercise, when the oxygen supply in the blood is unable to meet the demands of muscle tissue, myoglobin unloads its oxygen store allowing muscle contraction to continue efficiently
129
how does myoglobin become saturated?
Myoglobin becomes saturated with oxygen at lower oxygen tensions than haemoglobin and rapidly releases oxygen when oxygen tensions fall to low levels; myoglobin shows no Bohr shift as the advantageous effect of its high oxygen affinity would be lost
130
what is the function of capillaries?
SITE OF EXCHANGE of materials between blood & cells of tissues.
131
what are the differences in sizes of capillaries, arteries and veins?
- SMALL relative to size, to maintain a high pressure. (a)
- LARGE relative to size, to ease flow of blood back to heart (reduces friction). (v)
- TINY – 7 μm diameter, which is the same as diameter of RBC which are therefore close to capillary wall = short diffusion pathway for exchange. (c)
132
what are the type of walls in sizes of capillaries, arteries and veins?
- THICK – contains collagen to give strength to withstand the high pressure. (a)
- THIN – blood is at low pressure, therefore walls do not need to be thick & they do not need to stretch & recoil. Can be flattened by surrounding muscle contractions. (v)
- VERY THIN – to allow exchange of materials between blood and cells via tissue fluid. (c)
133
what do the arteries, veins and capillaries have in terms of elastic tissues?
- THICK layer of elastic tissue – allows wall to stretch & then recoil when heart pumps. The recoil maintains the high BP when the heart relaxes, which smooths out BP changes. (a)
- Thinner layer of elastic tissues (& collagen) since they do not need to stretch & recoil. (v)
- none (c)
134
what do the arteries, veins and capillaries have in terms of muscle walls?
- Walls contain smooth muscle to contract and constrict the artery – this narrows the lumen to decrease the blood flow & also maintains BP. (a)
- Walls contain a thinner layer of smooth muscle because vessels do not need to be constricted to reduce blood flow. (v)
- none (c)
135
what do the walls of the arteries, veins and capillaries have in terms of endothelium?
- Made of smooth endothelium. Folded and can unfold when artery stretches.(a)
- Made of smooth endothelium, not folded. (v)
- Capillary walls consist of a single layer of flattened endothelial tissue. Therefore there is a short diffusion distance for exchange. (c)
136
Do the veins, capillaries and arteries have valves?
- No valves, except at exit from ventricles. (a)
- Valves present to help blood flow back to heart and prevent it flowing in the opposite direction (unidirectional flow). (v)
- no valves (c)
137
heart rate
the number of beats per minute (bpm)
138
how do you calculate heart rate?
60s / time taken for one heat beat or cardiac cycle
139
stroke volume
volume of blood forced out of the heart in each beat
140
how do you calculate stroke volume?
cardiac output / heart rate
141
cardiac output
volume of blood released from the heart per minute
142
how do you calculate cardiac output?
stroke volume x heart rate
