3.3.4.1 Mass Transport In Animals Flashcards
(22 cards)
Role of red blood cells in transport
Contain lots of Heamoglobin (Hb)
No nucleus & biconcave shape so lots of space for Hb, high SA:V and short diffusion distance
Hb associates with lots of O at the lungs where partial pressure O is high
This form oxyheamogolbin which transports O. Each can carry 4 O molecules
Hb dissociates from O when partial pressure of O is low
Describe structure of haemoglobin
Protein with quaternary structure
Made of 4 polypeptide chains
Each chain contains a Haem group contains an iron ion (Fe+)
Loading and unloading of O in relation to oxyheamoglobin curve
Areas with low partial pressure of oxygen:
-Hb has low affinity for O
-so O readily unloads/disassociates with Hb
- So % saturation is low
Areas with high partial pressure of O:
-Hb has high affinity
-so Hb associates/loads with O
-% of saturation is high
Explain how O binds and creates an oxygen dissociation curve
Binding of the first oxygen changes tertiary/quaternary structure of Hb
This uncovers the Haem group binding sites, making further binding easier
Evidence for this
At low partial pressure of O- as O increases there is little increase in saturation when first binding
At high partial pressure of O- as O increases there is a big increase in saturation, this shows it’s got easier for oxygens to bind
What is the Bohr effect
Effect of CO2 conc on dissociation of oxyhemoglobin
Effect of CO2 conc on dissociation of oxyhaemoglobin
Blood CO2 increases due to increased respiration
Lowers blood PH
Reduces Hb affinity for o shape changes slightly
So faster unloading of Onto respiring cells
General pattern of blood circulation in a mammal
Deoxygenated blood in the right atrium (vena cava)
Down to right ventricle
Pulmonary artery to the lungs
Oxygenated blood into left atrium (pulmonary vein)
Done to left ventricle and to the rest of the body by the aorta
Importance of double circulated system
Prevents mixing of de/oxygenated blood
Blood is fully saturated with O
Blood can be pumped at a higher pressure, substance moved from body cells quicker
Blood vessels entering/leaving the kidney
Renal arteries-oxygenated blood I got the kidneys
Renal veins deoxygenated blood to the vena cava from the kidney
What are the coronary arteries
Blood vessels that carry oxygenated blood to the heart muscles
How dose blood move in the heart?
3 moves
Atrial systole:
-atria contract
-their volume decreases so pressure increases
-AV (atrioventricular values ) open when pressure in the atrium is greater than in the ventricles
-SV(semilunar valves) shut
-blood goes into ventricles
Ventricular systole:
-ventricles contract
-their volume decreases, pressure increases
-AV valves shut when pressure in ventricles are greater than atrium
-SV valves open
-blood rushes out of the heart
Diastole:
-atrium and ventricles relax
-volume increases so pressure decreases
-SV values shut when pressure in arteries exceeds ventricles
-AV values open
-so blood fills the atrium from the veins and flows in the ventricles
When do SV and AV valves open and close?
SV:
-close when artery pressure is higher than ventricle to prevent back-flow
-open when ventricle pressure is high than artery
AV:
-close when ventricle pressure is higher than atrium, preventing back flow
-open when pressure in atrium is higher than ventricle
How can heart rate be calculated
60/length of 1 cardiac cycle
Equation for cardiac output
Stroke volume(volume of blood pumped in each heart beat) X heart rate (bpm)
Structure of arteries
Thick smooth muscle tissue-can maintain pressure
Thick elastic tissue - can stretch and recoil to reduce pressure surges and maintain bp
Thick wall - withstand high pressure
Smooth folded endothelium - reduces friction
Narrow lumen - increases/maintains pressure
Structure of arterioles
Thick smooth muscle- contracts to reduces blood flow to capillaries (narrowing lumen)
Or can relax to allow more blood flow to capillaries (widens lumen)
Structure of capillaries
1 cell thick wall- reduces diffusion distance
Large network of capillaries - increases SA
Narrow lumen - reduces blood flow rate so more time for diffusion
Pores in walls between cells- allows larger substances though
Structure of veins
Wider lumen- less resistance to blood flow
Valves - prevents back-flow
Little elastic muscle- low bp
Formation of tissue fluid
Arteriole end of capillaries- higher hydrostatic pressure inside capillaries (contraction of ventricles) than tissue fluid. This forces water (and dissolved substances) out of capillaries. Large proteins remain in the capillaries
Return of tissue fluid to circulatory system
Venule end of capillaries:
Hydrostatic pressure reduces and fluid leave the capillaries.
As water is lost there is an increase of conc of all proteins, this lowers water potential in capillaries-lower than that of tissues fluid.
Water enters capillaries from tissue fluid by osmosis down the water potential gradient.
Excess water is taken by the lymph capillaries and returned to the circulatory system though veins
What causes excess tissue fluid to build
Low conc of proteins:
-Water gradient is reduced
-more tissue fluid formed at arteriole end-less water absorbed.
Lymph system can’t drain quick enough
High Bp:
-High hydrostatic pressure
-increases outward pressure (arteriole end) and reduces inward pressure (venule end).
-more tissue fluid formed at arteriole end as less water is absorbed
-lymph system can’t drain fast enough
