mass transport in animals Flashcards
organisms
Describe the role of red blood cells & haemoglobin (Hb) in oxygen transport
● Red blood cells contain lots of Hb
○ No nucleus & biconcave → more space for Hb, high SA:V & short diffusion distance
● Hb associates with / binds / loads oxygenate gas exchange surfaces (lungs) where partial
pressure of oxygen (pO2) is high
● This forms oxyhaemoglobin which transports oxygen
○ Each can carry four oxygen molecule, one at each Haem group
● Hb dissociates from / unloads oxygen near cells / tissues where pO2
is low
Describe the structure of haemoglobin
● Protein with a quaternary structure
● Made of 4 polypeptide chains
● Each chain contains a Haem group containing an iron ion (Fe2+)
The haemoglobins are a group of chemically similar molecules found in many different organisms
Describe the loading, transport and unloading of oxygen in relation to the oxyhaemoglobin dissociation curve
Explain how the cooperative nature of oxygen binding results in an S-shaped (sigmoid) oxyhaemoglobin dissociation curve
- Binding of first oxygen changes tertiary / quaternary structure of haemoglobin
- This uncovers Haem group binding sites, making further binding of oxygens easier
Describe evidence for the cooperative nature of oxygen binding
● A low pO2 as oxygen increases there is little / slow increase in % saturation of Hb with oxygen
○ When first oxygen is binding
● At higher pO2, as oxygen increases there is a big / rapid increase in % saturation of Hb with oxygen
○ Showing it has got easier for oxygens to bind
What is the Bohr effect?
Effect of CO2 concentration on dissociation of oxyhaemoglobin → curve shifts to right
Explain effect of CO2 concentration on the dissociation of oxyhaemoglobin
- Increasing blood CO2 eg. due to increased rate of respiration
- Lowers blood pH (more acidic)
- Reducing Hb’s affinity for oxygen as shape / tertiary / quaternary structure changes slightly
- So more / faster unloading of oxygen to respiring cells at a given pO2
-Describe evidence for the Bohr effect
-At a given pO2 %, the saturation of Hb with oxygen is lower
Explain the advantage of the Bohr effect (eg. during exercise)
More dissociation of oxygen → faster aerobic respiration / less anaerobic respiration → more ATP produced
Explain why different types of haemoglobin can have different oxygen
transport properties
● Different types of Hb are made of polypeptide chains with slightly different amino acid sequences
● Resulting in different tertiary / quaternary structures / shape
● So they have different affinities for oxygen
Explain how organisms can be adapted to their environment by having
different types of haemoglobin with different oxygen transport properties
Describe the general pattern of blood circulation in a mammal
Closed double circulatory system - blood passes through heart twice for every circuit around body:
1. Deoxygenated blood in right side of heart pumped to lungs; oxygenated returns to left side
2. Oxygenated blood in left side of heart pumped to rest of body; deoxygenated returns to right
Suggest the importance of a double circulatory system
● Prevents mixing of oxygenated / deoxygenated blood
○ So blood pumped to body is fully saturated with oxygen for aerobic respiration
● Blood can be pumped to body at a higher pressure (after being lower from lungs)
○ Substances taken to / removed from body cells quicker / more efficiently
Draw a diagram to show the general pattern of blood circulation in a
mammal, including the names of key blood vessels
Name the blood vessels entering and leaving the heart and lungs
● Vena cava – transports deoxygenated
blood from respiring body tissues → heart
● Pulmonary artery – transports
deoxygenated blood from heart → lungs
● Pulmonary vein – transports oxygenated
blood from lungs → heart
● Aorta – transports oxygenated blood
from heart → respiring body tissues
Name the blood vessels entering and leaving the kidneys
● Renal arteries – oxygenated blood → kidneys
● Renal veins – deoxygenated blood to vena cava from kidneys
Name the the blood vessels that carry oxygenated blood to the heart muscle
Coronary arteries - located on surface of the heart, branching from aorta
Label a diagram to show the gross structure of the human heart (inside)
Suggest why the wall of the left ventricle is thicker than that of the right
● Thicker muscle to contract with greater force
● To generate higher pressure to pump blood around entire body
Explain the pressure & volume changes and associated valve movements during the cardiac cycle that maintain a unidirectional flow of blood
Explain how graphs showing pressure or volume changes during the cardiac cycle can be interpreted, eg. to identify when valves are open / closed
Semilunar valves closed
● Pressure in [named] artery higher than in ventricle
● To prevent backflow of blood from artery to ventricles
Semilunar valves open
● When pressure in ventricle is higher than in [named] artery
● So blood flows from ventricle to artery
Atrioventricular valves closed
● Pressure in ventricle higher than atrium
● To prevent backflow of blood from ventricles to atrium
Atrioventricular valves open
● When pressure in atrium is higher than in ventricle
● So blood flows from atrium to ventricle
How can heart rate be calculated from cardiac cycle data?
Heart rate (beats per minute) = 60 (seconds) / length of one cardiac cycle (seconds)
Describe the equation for cardiac output
Cardiac output (volume of blood pumped out of heart per min)
= stroke volume (volume of blood pumped in each heart beat) x heart rate (number of beats per min)
Explain how the structure of arteries relates to their function
Function – carry blood away from heart at high pressure
Explain how the structure of arterioles relates to their function
Function – (division of arteries to smaller vessels which can) direct blood to different capillaries / tissues
● Thicker smooth muscle layer than arteries
○ Contracts → narrows lumen (vasoconstriction) → reduces blood flow to capillaries
○ Relaxes → widens lumen (vasodilation) → increases blood flow to capillaries
● Thinner elastic layer → pressure surges are lower (as further from heart / ventricles)
Explain how the structure of capillaries relates to their function
Function - allow efficient exchange of substances between blood and tissue fluid (exchange surface)
Explain how the structure of veins relates to their function
Function – carry blood back to heart at lower pressure
● Wider lumen than arteries → less resistance to blood flow
● Very little elastic and muscle tissue → blood pressure lower
● Valves → prevent backflow of blood
Explain the formation of tissue fluid
At the arteriole end of capillaries:
1. Higher blood / hydrostatic pressure inside capillaries (due to
contraction of ventricles) than tissue fluid (so net outward force)
2. Forcing water (and dissolved substances) out of capillaries
3. Large plasma proteins remain in capillary
Explain the return of tissue fluid to the circulatory system
At the venule end of capillaries:
1. Hydrostatic pressure reduces as fluid leaves capillary (also due to friction)
2. (Due to water loss) an increasing concentration of plasma proteins lowers water potential in
capillary below that of tissue fluid
3. Water enters capillaries from tissue fluid by osmosis down a water potential gradient
4. Excess water taken up by lymph capillaries and returned to circulatory system through veins
Suggest and explain causes of excess tissue fluid accumulation
● Low concentration of protein in blood plasma
○ Water potential in capillary not as low → water potential gradient is reduced
○ So more tissue fluid formed at arteriole end / less water absorbed at venule end by osmosis
○ Lymph system may not be able to drain excess fast enough
● High blood pressure (eg. caused by high salt concentration) → high hydrostatic pressure
○ Increases outward pressure from arteriole end AND reduces inward pressure at venule end
○ So more tissue fluid formed at arteriole end / less water absorbed at venule end by osmosis
○ Lymph system may not be able to drain excess fast enough
What is a risk factor? Give examples for cardiovascular disease
● An aspect of a person’s lifestyle or substances in a person’s body / environment
● That have been shown to be linked to an increased rate of disease
● Examples - age, diet high in salt or saturated fat, smoking, lack of exercise, genes
spot the mistake ““[Named organism] has a [higher / lower] affinity for oxygen.”
It is the organism’s haemoglobin that has a high / low affinity for
oxygen, not the organism itself.
true or false “Capillaries are the blood vessels with the lowest blood pressure.”
Pressure drops from arteries, to arterioles, to capillaries, to
venules, to veins. The vena cava has the lowest blood pressure.
true or false “Tissue fluid / blood / plasma leaves
capillaries.”
Water (and some dissolved substances) are forced out of capillaries, resulting in tissue fluid.
what’s the importance of muscle contraction in arteriole walls
Contraction narrows the lumen of arterioles,
reducing blood flow to capillaries.
explain what causes the pH level in blood to be reduced
- aerobic respiration will produce carbon dioxide
- carbon dioxide dissolves in blood forming acid
- increases hydrogen ion concentration
