7.Mass Transport Flashcards
What is the structure of haemoglobin
Primary-sequence of amino acids in the four polypeptides
Second-each polypeptide coiled into a helix
Tertiary-each polypeptide folded into precise shape -important
Quarte-all 4 linked together to form spherical molecule, each polypeptide associated with haem group contains a ferrous ion
What does the ferrous ion in the haem group do
Each one can combine with single oxygen molecule, so 4 oxygen molecules carried by one haemoglobin molecule in humans
What is unloading and loading oxygen
Process by which haemoglobin binds with oxygen is loading or associating.
Process by which haemoglobin releases its oxygen is unloading or dissociating
Haemolglon with a high affinity for oxygen, take up more easily but release less easily and haemoglobin with low affinity for oxygen, take up oxygen ,es easily but release more easily
To be efficient at transporting oxygen haemglobin must:
Readily associate with oxygen at surface of gas exchange
Readily dissociate from oxygen at tissues requiring it
How does haemoglobin achieve both properties
- changes affinity under different conditions
- shape changes in presence of certain substances eg carbon dioxide
- new shape haemoglobin molecule binds more loosely to oxygen as result it releases it oxygen
What’s the oxygen dissociation curve
Graph showing the relationship between the saturation of haemoglobin with oxygen and the partial pressure of oxygen
How to understand different oxygen dissociation curves on the graph
Further to the left-greater the affinity of haemoglobin (loads readily but unloads less easily)
Further to right-lower affinity of haemoglobin (loads less readily )
Explanation of the oxygen dissociation curve
1-shape of haemoglobin means hard for first oxygen to bind, low oxygen conc little oxygen binds, gradient of curve is shallow
2-binding of first oxygen changes shape of haemoglobin, easier for next two oxygen molecules to bind to other subunits
3-therefore smaller increase in partial pressure needed to bind second oxygen than first one, positive cooperativity gradient steepens
4-after binding of 3rd harder to bind fourth as probability of finding empty subunit is less likely, gradient levels off
What’s the Bohr effect
The greater the conc of carbon dioxide the more readily haemoglobin releases its oxygen.
Why does the conc of carbon dioxide change shape of haemoglobin
Dissolved carbon dioxide is acidic and the low pH causes haemoglobin to change shape
What are features of transport systems
- suitable medium for carrying materials, liquid base on water as dissolves substances and can be breathed as gas
- form of mass transport, moved around in bulk more rapid than diffusion
- closed system of tubular vessels, branching network throughout organism
- mechanism for moving transport medium, requires pressure difference between one part and another
How is mechanism of mass transport achieved
1-use muscular contraction of body muscle or of a specialised pumping organ eg heart
2-rely on natural passive processes eg evaporation of water
What is a double closed circulatory system
Blood is confined to vessels and passes twice through the heart in each complete circuit of the body
Because when passed through lungs pressure reduced
What are the two sections of the heart and the differences between them
Atrium - thin walled and elastic and stretches as collect blood
Ventricle - thicker muscular wall as it has to contract strongly to pump blood some distance
Where does blood from left and right ventricle go to?
Left- goes to body
Right - goes to lungs (thinner muscular wall)
Where are the bicuspid valves
Between atrium and ventricles
Called atrioventricular valves
Where does the aorta connect to
Left ventricle and carries oxygenated blood around body
Where is ve a cava connected to
Right atrium and brings in deoxygenated blood from tissues
Where is pulmonary artery connected to
Right ventricle and carries deoxygenated blood to lungs
Where is pulmonary vein connected too
Left atrium and brings oxygenated blood back from lungs
What are coronary arteries
Blood vessels that supply the heart
Branches off aorta
Blockage of these can cause myocardial infarction (heart attack)
What is diastole
Relaxation of the heart
What happens during diastole
- Blood return to atria via vena cava and pulmonary vein
- Atria fill-pressure increases
- once pressures exceeds that of ventricles atrioventricular valves open
- aided by gravity
- muscles of walls relaxed, ventricle walls recoil which reduces pressure
- pressure in ventricle lower than in aorta and pulmonary artery, semi lunar valves shut
- dub sound
What’s atrial systole
Contraction of atria
What happens in atria systole
Contraction of aria walls along with recoil of ventricles fro es remaining blood in atria into ventricles, ventricle walls still relaxed
What is ventricle systole
Contraction of ventricles
What happens during ventricle systole
Short delay after atria contraction
Allows ventricles to fill, then walls contract simultaneously
Increase blood pressure, forces shut A.V valves prevents backflow
Lub is sound of av shutting
Increased pressure
Pressure exceeds that of aorta and pulmonary artery
Blood forced into them
What’s the function of valves
Atrioventricular
Semi lunar
Pocket valves
All prevent backflow and ensure blood moves “forward”
What’s the equation for cardiac output
Heart rate x stroke volume
What are arteries
Carry blood away from heart and into arterioles
What are arterioles
Smaller arteries that control blood flow from arteries to capillaries
What are capillaries
Tiny vessels linking arterioles to veins
What are veins
Vessels carry blood from capillaries back to heart
What basic structures do arteries arterioles and veins have in common
Tough fibrous outer layer Muscles layer Elastic layer Thin inner lining (endothelium) Lumen
Artery structure related to function
- Thick muscle layer-can be constricted and dilated control volume of water through
- thick elastic-maintain high blood pressure, stretches and recoils, pressure surges
- great thickness of wall-resists vessel bursting under pressure
- no valves-constant pressure due to heart pumping
Arterioles structure related to function
Muscle layer thicker than arteries-restrict lumen, resist blood flow controls movement into capillaries
Elastic layer thinner than arteries-blood pressure is lower
Vein structure related to function
Muscle layer thin-blood away from tissue so can’t control flow of blood to tissue
Elastic layer thin- too low blood pressure to cause recoil action
Overall thickness is small-pressure within is so low no risk of bursting
Valves through out-no backflow as low pressure, ensures when muscles contract blood flow in one direction
Capillary structure related to function
Walls mainly lining layer-extremely thin, rapid diffusion
Numerous and highly branched-large surface area for exchange
Narrow lumen-red blood cells squeezed against side of capillary
Spaces between endothelial cells-allow white blood cells to escape and dal with with infections in tissues
What is tissue fluid made of
Water liquid
Contain glucose amino acids fatty acids oxygen and ions in solution
The means by which materials exchanged between blood and cells
Immediate environment of cells
Formed from blood plasma
How is tissue fluid formed
- Pumping of heart creates hydrostatic pressure at arteirole end
- Hydrostatic pressure causes tissue fluid to move out of blood -plasma
- pressure is enough to force small molecules out of cappliaries, ultrafiltration
-opposing outward pressure is:Hydrostatic pressure of tissue fluid in capillaries resist outward movement and lower water potential of blood due to blood plasma proteins causes water to move back into blood in cappliaries
How does tissue fluid return to circulatory system
- loss of fluid from cappliaries reduces hydrostatic pressure
- when blood reaches venous end hydrostatic pressure considerably lower than that of tissue fluid
- tissue fluid forced back into capillaries
- plasma lost water and stilll contain proteins, lower W.P than tissue fluid
- water leaves tissues via osmosis down w.p gradient
- not all returns to capillaries, remainder carried in lymphatic system
What’s the lymphatic system
System of vessels that begin in tissues
Resemble capillaries except have dead ends. Gradually merge into larger vessels that from networks throughout body, larger vessels drain contents back into bloodstream via two ducts that join veins close to heart
How are the contents of lymphatic system moved?
Hydrostatic pressure of tissue fluid that left capillaries
Contraction of body muscles that squeeze lymph vessels-have valves to maintain one directional flow
Give two reasons why phoneyer does not truly measure rate of transpiration
You assume that all water is lost by evaporation but some molecules will be used in photosynthesis or to make plant turgid
