Module 3 - Mass transport in animals Flashcards
3 marks
The oxygen dissociation curve for heamoglobin shifts right during vigorous exercise. Explain the advanatge of this shift
- Low pH due to increased CO2/ increased respiration
- Increased dissociation of haemoglobin
- Oygen diffuses from r.b.c to tissues
3 marks
How does exposure to CO affect loading and unloading of oxygen by haemologlobin
- A low Po2 Hb exposed to CO has a higher affinity for oxygen than normal Hb
- In respiring tissue its unloading less oxygen than it should
- At high Po2 (lungs) it has a lower affinity for oxygen than normal Hb- only 50% saturation of the no CO Hb (less oxygen loaded at lungs)
3 marks
Explain why the thickness of the aorta wall changes all the time during each cardiac cycle
- Aorta wall stretches because ventricle contracts (pressure increases)
- Aorta wall recoils because ventricle relaxes (pressure falls)
- Maintain smooth flow / pressure
What does atheroma lead to
Atheroma leads to blockage of coronary artery
Name the type of blood vessel that controls blood flow to muscles and explain how these blood vessels change blood flow during exercise.
- Arteriole;
- (Circular/smooth) muscle relaxes;
- Widens/dilates (lumen of) blood vessel so increases blood flow;
2 marks
There is a small increase in pressure and in rate of blood flow in the aorta.
Explain how this happens and its importance.
- Elastic recoil of the aorta wall
- Smooths the blood flow
What factor limits the minimum internal diameter of the lumen of a capillary
Diameter of red blood cell
2 marks
How is the pressure in the ventricle related to the thickness of ventricle wall
- Thickness of wall increases because ventricle wall contracts
- Contraction caused by increase in pressure
3 marks
Explain why high blood pressure leads to the accumulation of tissue fluid
- High blood pressure (as ventricle contracts)= high hydrostatic pressure
- Increase in outward pressure from arteriole end of capillary
- So more tissue fluid formed
3 marks
Why does venule end of capillary have lower blood plasma water potential
- Water has left capillary
- Proteins in blood too large to leave
- Higher concentration of blood plasma proteins
Why does carbonmonoxide kill people. Use loading and unloading of O2.
At low pO2, Hb exposed to CO has higher affinity for O2 than normal Hb
In respiring tissues it is unloading less O2 than it should
At high PO2, it has lower affinity for O2 than normal Hb- less O2 loaded to lungs
6 marks
Explain how tissue fluid is formed and how it may be returned to the circulartory system
- High hydrostatic pressure at arterial end
- Soluble molecules pass out
- Proteins remain - too large
- This lower water potential at venule end
- Water moves back into venule end via osmosis
- Lymphatic system collects any excess tissue fluid which returns to blood
2 marks
High absorption of salt from the diet can result in a higher than normal
concentration of salt in the blood plasma entering capillaries. This can lead to a build-up of tissue fluid. Explain how.
- Higher salt results in higher blood pressure–> higher hydrostatic pressure
- So more fluid forced out of arteriole end of capillary
OR - Higher salt results in lower water potential of tissue fluid
- So less water returns to capillary by osmosis at venule end
6 marks
Explain how the structures of the walls of arteries, veins and capillaries are related to their functions.
Artery
1. thickest wall, enabling it to carry blood at high pressure / withstand pressure surges
2. most elastic tissue, which evens out pressure
3. most muscle which maintains pressure
4. muscle in wall to control blood flow
Vein
5. thin wall does not have to withstand high pressure
Capillary
6. thin wall, allowing diffusion
7. only endothelium present, allowing short diffusion pathway
All vessels
8. have endothelium that reduces friction
Does artery or vein have larger lumen
Arteries have smaller lumens than veins
3 marks
Explain how oxygen in a RBC is made available for respiration in active tissues
- Low pH due to increased CO2 due to increased respiration;
- Increased dissociation of haemoglobin
- Oxygen diffuses from r.b.c. to tissues
2 marks
A decrease in the pH of blood plasma reduces the affinity of haemoglobin for oxygen.
Explain how aerobic respiration in cells leads to a change in the pH of blood plasma.
- CO2 is produced
- Forms carbonic acid
- Hydrogen ions released
2 marks
What is the advantage to tissue cells of a reduction in the affinity of haemoglobin for oxygen when the plasma pH decreases?
- Low pH due to high rates of respiration
- Cells need more oxygen
- More oxygen released
4 marks
Describe how oxygen in the air reaches capillaries surrounding alveoli in the lungs.
Details of breathing are not required.
- Trachea and bronchi and bronchioles
- Down pressure gradient
- Down diffusion gradient
- Across alveolar epithelium
- Across capillary endothelium
2 marks
The oxygen dissociation curve of the fetus is to the left of that for its mother. Explain the advantage of this for the fetus.
- Higher affinity for oxygen at low partial pressure
- Oxygen moves from mother to fetus
5 marks
Explain how the heart muscle and the heart valves maintain a one-way flow of blood from the left atrium to the aorta.
- Atrium has higher pressure than ventricle (due to contraction) causing atrioventricular valves to open
- Ventricle has higher pressure than atrium (due to contraction) causing atrioventricular valves to close
- Ventricle has higher pressure than aorta causing semilunar valve to open
- Higher pressure in aorta than ventricle (as heart relaxes) causing semilunar valve to close
- Contraction causes increase in pressure
3 marks
The oxygen dissociation curve for haemoglobin shifts to the right during vigorous exercise.
Explain the advantage of this shift.
- Lower affinity for oxygen
- To muscles/tissues
- For high respiration
The water potential of the blood plasma is more negative at the venule end of the capillary than at the arteriole end of the capillary. Explain why
- Water has left the capillary
- Proteins in blood too large to leave capillary
- Increasing concentration of blood proteins
2 marks
Other than causing slow blood flow, explain one advantage of capillaries being narrow.
- Short distance between blood and outside of capillary
- Large surface area (of blood) in contact with walls of capillaries
- Fast exchange / fast diffusion
2 marks
What is the function of the coronary arteries?
- Carry oxygen
- To heart muscles
6 marks
Arteries and arterioles take blood away from the heart.
Explain how the structures of the walls of arteries and arterioles are related to their functions.
Elastic tissue
1. Elastic tissue stretches under pressure then recoils
2. Evens out pressure / flow
Muscle
3. Muscle contracts to reduce diameter of lumen / vasoconstriction
4. Changes blood flow
Epithelium
5. Epithelium smooth
6. Reduces friction
2 marks
Give two structural features of an aorta wall and explain how they are related to the function of an aorta.
- Smooth muscle withstands high blood pressure
- Elastic tissue stretches and recoils maintains/smooths blood pressure
- Smooth endothelium reduces friction
- Protein coat prevents artery wall splitting
6 marks
Explain how oxygen is loaded, transported and unloaded in the blood.
1) Haemoglobin carries oxygen / has a high affinity for oxygen / oxyhaemoglobin
2) In red blood cells
3) Loading/uptake/association in lungs
4) At high partial pressure of oxygen
5) Unloads/ dissociates / releases to respiring cells/tissues
6) at low partial pressure of oxygen
7) Unloading linked to higher carbon dioxide conc
3 marks
The oxygen dissociation curve of the foetus is to the left of that for its mother.
Explain the advantage of this for the foetus.
1) Have a higher affinity / loads more oxygen
2) At low pO2
3) So oxygen moves from mother to fetus
4 marks
Explain how oxygen in a red blood cell is made available for respiration in active tissues.
1) Respiration increases carbon dioxide conc
2) So increases rate at which oxygen is dissociated
3) Low partial pressure of oxygen in tissues/plasma
4) So oxygen diffuses from red blood cells to tissues
4 marks
Describe and explain four ways in which the structure of a capillary adapts it for the exchange of substances between blood and the surrounding tissue.
- permeable capillary wall
- Thin epithelium walls, reduces diffusion distance
- flattened endothelium cells, reduces diffusion distance
- fenestrations, allows large molecules through
- small diameter, gives a large surface area to volume / short diffusion distance
- narrow lumen, reduces flow rate giving more time for diffusion
- red blood cells in contact with wall- more time for diffusion
3 marks
Give the pathway a red blood cell takes when travelling in the human circulatory system from a kidney to the lungs. Do not include descriptions of pressure changes in the heart or the role of heart valves in your answer.
- Renal vein
- Vena cava to right atrium
- Right ventricle to pulmonary artery
1 mark
Give one other way, besides ventillation, that helps to maintain the difference in oxygen concentration.
Ciculation of blood
Equation for pulmonary ventillation
PV= breathing rate x tidal volume
2 marks
When a person starts to breathe out, the percentage of oxygen in the air first exhaled is the same as the percentage of oxygen in the atmospheric air. Explain why.
- Air is dead space/ not from trachea/ bronchi
- Gas exchange only in alveoli
Equation for cardiac output
CO= breathing rate x stroke volume
2 marks
In healthy lungs, a gradient is maintained between the concentration of oxygen in the alveoli and the concentration of oxygen in the lung capillaries. Describe how ventilation helps to maintain this difference in oxygen concentration.
In alveolus
1. Brings in air containing a high(er) oxygen concentration;
2. Removes air with a low(er) oxygen concentration
2 marks
Binding of one molecule of oxygen to haemoglobin makes it easier for a second oxygen molecule to bind. Explain why.
- Binding of first oxygen changes tertiary structure of haemoglobin
- Creates another binding site
2 marks
Describe the advantage of the Bohr effect during intense exercise
- Increases dissociation of oxygen
- For aerobic respiration at the tissues/muscles/cells
6 marks
Describe the 3 stages of the cardiac cycle with reference to all the valves and the cardiac muscles in the atria and ventricles
- Atrial systole
- Atria contracts amd ventricles relax
- Atrioventricular valve open and semi lunar valve closed
- Ventricular systole
- Ventricles contract and atria relax
- AVN closed and SLV open
- Diastole
- Ventricles and atria are both relaxed
- SLV closed and AVN open
6 marks
Explain the cellular response
- Antigen presenting cell- phagocyte, cancer cell, invaded host cell
- T helper cell receptors binds to APC presented antigens
- Cytokines released and stimulates T cells
- Triggers mitosis and differentiation of T cells (clonal selection)
- T cells differentiate to cytotoxic cells and T helper cells
- Cytotoxic cells release perforin
- Perforin destroys infected calls
- Only suitable when pathogens are inside host cells
5 marks
The vaccine for shingles is available on the NHS to everyone over 70. The vaccines contains a protein from the virus
Describe how the immune system would create antibodies after being exposed to the shingles vaccine
- Phagocyte will engulf antigen
- Forms antigen presenting cell
- Cellular respone: T helper cell activated by APC
- T helper cell activate B cell
- With complementary receptor
- Humoural response: B cell divides by mitosis
- B plasms cells secretes monoclonal antibodies
5 marks
Explain what is meant by herd immunity and suggest the advantages of it
- Herd immunity: Majority of the population is vaccinated
- Prevents transmission of pathogen in the community
- Reduces infection rate in population
- Can lead to eradication of disease
- Protects vulnerable populations, people who cannot have vaccines e.g. babies
- Prevents future pandemics
1 mark
Give formula for % saturation of Hb with O2
(Oxygenated Hb/ maximum saturation) x 100
2 marks
The first molecule of oxygen to bind causes a change in the shape of the haemoglobin molecule. This change of shape makes it easier for other oxygen molecules to bind to the haemoglobin molecule. Explain how the graph provides evidence for this.
- At low partial pressure of oxygen, little increase in saturation as oxygen increases
- (then) rapid rise as it gets easier for oxygen to bind
1 mark
Suggest one advantage of this change in the affinity of haemoglobin for oxygen.
Ensures rapid / more intake of oxygen in lungs / release of oxygen in tissues
Outline the route that blood takes through the heart
VC, RA, RV, Pulmonary Artery, Lungs, Pulmonary vein, LA, LV, Aorta
How does vein structure relate to its function?
Thin walls, wide lumen – low pressure. Valves to prevent back flow.
