circulatory system Flashcards
blood vessels, tissue fluid, haemoglobin
Give the pathway a red blood cell takes when travelling in the human circulatory system from a kidney to the lungs (3)
- renal vein
- vena cava to right atrium
- right ventricle to pulmonary artery
tissue fluid is formed from blood at the arteriole end of a capillary bed
explain how water from tissue fluid is returned to the circulatory system (4)
- plasma proteins remain
- creates a water potential gradient/ reduces water potential of blood
- water moves to blood by osmosis
- returns to blood by lymphatic system
describe 3 precautions the student should take when clearing away after a heart dissection (3)
- disinfect surfaces
- disinfect hands
- carry sharp instruments by holding handle
explain how an arteriole can reduce the blood flow into capillaries (2)
- muscle contracts
- constricts arteriole/ lumen
which blood vessel carries blood at the lowest pressure? (1)
vena cava
there is a small increase in pressure and in rate of blood flow in the aorta
explain how this happens and it’s importance (2)
- semi-lunar valves closed
- because pressure in aorta is higher than in ventricle
describe the advantage of the Bohr effect during intense exercise (2)
- increases disassociation of oxygen
- for aerobic respiration at the tissues
explain which and how a physiological change would allow for removal of increased carbon dioxide (2)
-increase in breathing rate
-similar pCO2 per breath but more breaths
EPO increases the percentage of red blood cells in blood, a heart attack is caused by a lack of glucose and oxygen being delivered to cardiac muscle, overuse of EPO can increase heart attack risk- suggest how (2)
- EPO causes blood to thicken
- thickened blood could block the coronary arteries
describe and explain the effect of increasing carbon dioxide concentration on the disassociation of haemoglobin (2)
- more oxygen disassociation
- by decreasing blood pH
explain how valve A (Atrioventricular) maintains a unidirectional flow of blood (2)
- pressure in left atrium is higher than in ventricle, causing valve to open
- pressure in ventricle is then higher than in the atrium, causing it to close
name the blood vessels that carry blood to the heart muscle (1)
coronary arteries
binding of one molecules of oxygen to haemoglobin makes it easier for a second oxygen to bind, explain why (2)
- binding of first oxygen changes the tertiary structure of haemoglobin
- uncovers another binding site
explain the role of the heart in the formation of tissue fluid (2)
- contraction of ventricle produces high blood pressure
- this forces water and some dissolved substances out of blood capillaries
lymphoedema is a swelling in legs which may be caused by a blockage in the lymphatic system, suggest how a blockage in the lymphatic system could cause lymphoedema (1)
excess tissue fluid cannot be reabsorbed/ it builds up
explain how changes in the shape of haemoglobin result in the S-shaoed oxyhaemoglobin disassociation curve for HbA (2)
-first oxygen binds to Hb causing change in shape
- shape change of Hb allows more oxygen to bind easily
explain a property of iron ions that enables these ions to carry out their role in red blood cells (2)
- is charged
- binds with oxygen
how does composition of blood in the pulmonary artery of a fetus differ from composition of blood in pulmonary artery of mother (2)
- fetal blood has more oxygen
- because gas exchange occurs in the placenta
hydrostatic pressure falls from the arteriole end of the capillary to the venule end, explain why (2)
loss of water from capillary
high blood pressure leads to an accumulation of tissue fluid. Explain how (3)
- high blood pressure means high hydrostatic pressure
- increases outward pressure from arterial end
- so more tissue fluid formed
water potential of blood plasma is more negative at the venule end than at the arteriole end. Explain why (3)
- water has left the capillary
- proteins too large to leave capillary
- increasing concentration of blood proteins
how is tissue fluid formed (1)
small molecules such as amino acids and glucose are forced out of the capillary at the arterial end
describe the quaternary structure of haemoglobin
4 polypeptides
each polypeptide has a haem group that contains an Fe2+ ion
explain how DNA leads to different haemoglobin molecules having different affinities for O2
different base sequence so different amino acid sequence so different tertiary structure and quaternary structure = different affinities for O2
when the body is at rest only one of the four O2 molecules carried by Hb is normally released into the tissues
suggest why this could be an advantage when the organism becomes more active
if all O2 molecules were released there would be none in reserve to supply tissues when they were more active
carbon monoxide occurs in car exhaust fumes. it binds permanently to haemoglobin instead of O2- suggest why a person breathing in car fumes may lose consciousness
CO occupies all binding sites on Hb instead of O2
so no O2 carried to tissues such as the brain
these tissues cant respire and function, so person loses consciousness
what does the curve show about Hb affinity if the curve is to the:
- left
-right
to the left: Hb has a HIGHER affinity for O2, loads O2 more readily
to the right: Hb has a LOWER affinity for O2, loads O2 less readily
what effect does an increased CO2 concentration have on the affinity of Hb
increased CO2 concentration REDUCES affinity of Hb, unloads O2 more easily
at tissues there is high concentration of CO2 so Hb has low affinity and releases O2 more readily
what effect does CO2 concentration have on affinity of Hb at the LUNGS
- low CO2 concentration as it is constantly being excreted
- this raises pH
- higher pH changes the shape of the Hb which enables it to LOAD O2 more readily
- increased affinity of Hb
what effect does CO2 concentration have on affinity of Hb at the TISSUES
- CO2 produced by respiring cells
- CO2 dissolves in blood and lowers its pH
- this changes shape of Hb which enables it to UNLOAD O2 more easily
- decreased affinity of Hb
- more O2 unloaded
- more O2 available for respiration
suggest whether disassociation curve of a pigeon is shifted to left or right of a human
RIGHT
so Hb has a lower affinity for O2 and unloads O2 more easily at the respiring tissues
quicker respiration
diasassociation curve of a mouse is shifted to the right of a humans
explain how this changes the way O2 is unloaded from mouse Hb compared to human Hb
suggest an advantage this has for the maintenance of body temperature in mice
- unloads more easily in the mouse as it has lower affinity
- O2 more easily unloaded to tissues, so more respiration means more heat is produced, which helps maintain body temperature
ice fish live in the antarctic and are the only vertebrates to completely lack Hb.
suggest 1 reason why they can survive in the seas around antarctica without Hb in their blood
temperatures in antarctic waters are LOW so respiration rates of cold blooded animals is also low
respiration needs O2, if they respire less they need less O2
ice fish rely on water for O2- the amount of O2 dissolved in water is adequate enough to supply their needs
why does blood return to the heart after leaving the lungs
after going through lungs, pressure of blood is reduced
if it were to pass immediately to whole body circulation would be very slow
goes to heart before to increase pressure so circulation is faster
state 2 factors that make it more likely that the organism will have a circulatory pump e.g the heart
- low SA:V ratio
- high metabolic rate
state the main advantage of double circulation found in mammals
it increases blood pressure so increases rate of blood flow to tissues
suggest and explain why the rise and fall in blood pressure in the aorta is greater than in small arteries (3)
- the aorta is directly connected to heart (LV) this creates the highest pressure
- there are more elastic fibres in aorta
- elastic fibres stretch and recoil to maintain high BP
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 membrane
Wall is single cell thick- reduces diffusion distance
Flattened endothelial cells- reduces diffusion distance
Fenestrations allow large molecules through
Small diameter increases SA:V ratio, short diffusion distance
Explain how tissue fluid is formed and how it may be returned to the circulatory system. (6)
Hydrostatic pressure of blood is high at arterial end
Fluid passes out
Proteins remain
This lowers water potential of blood
Water moves back into venous end of capillary by osmosis
Lymph system collects excess tissue fluid which then returns to blood
what makes up tissue fluid
water
amino acids
fatty acids
salts
sugars
hormones
white blood cells
metabolic waste products.
