Transport in Animals Flashcards
What are the atria?
Thin muscular walls receiving (low pressure) blood returning to the heart in veins
What does the right ventricle do?
contracts to move deoxygenated blood into the lungs via the pulmonary artery
What does the right atrium do?
Receives deoxygenated blood via the vena cava
What does the left atrium do?
receives oxygenated blood via the pulmonary veins
Features of arteries
- Blood is carried under higher pressure than veins
- do not posses valves except for the aorta and pulmonary artery
- thicker wall and smaller lumen than veins + more elastic fibres and smooth muscle fibres
- carry oxygenated blood except for the pulmonary arteries
How to work out Cardiac Output?
stroke volume (cm^3) x heart rate (min^-1)
what is the function of the capillaries?
to exchange of materials such as oxygen & carbon dioxide between the blood and body cells.
Describe the process of the formation of tissue fluid
- at arteriole end of capillary the hydrostatic pressure of the blood plasma is much higher than the osmotic pressure of the tissue fluid so water and small molecules osmose into and form the tissue fluid
- plasma protein and blood cells stay in the capillary
- loss of fluid and high frictional resistance reduces blood pressure
- the large plasma proteins which remain in the blood reduce the water potential of the blood plasma causing the osmotic uptake of water into the capillaries
- less hydrostatic pressure at the venule end of the capillary means that due to the osmotic pressure of the tissue fluid some of the water is reabsorbed by osmosis
what is lymph + why does it form?
- this process is too slow to re-absorb all the filtered plasma and some of the tissue fluid enters lymph capillaries
- this tissue fluid is now called lymph which eventually return to the blood when the lymph capillaries join to form lymph vessels
what is haemoglobin?
An iron containing pigment, which loosely and reversibly combines with oxygen to form oxyhaemoglobin
what is the oxyhaemoglobin dissociation curve
a graph showing the relationship between the partial pressure O2 and percentage saturation of haemoglobin
normally an S shape
Describe the Loading, transport and unloading of oxygen (3)
- deoxygenated blood enters the lung capillaries
- alveoli contain a high conc of oxygen = conc gradient for diffusion of O2
- O2 enters RBC and combines with Hb to form OxyHb
why is the HbO2 dissociation curve an S shape
- a molecule of O2 binds to one of the four haem units causing a slight change in the tertiary structures of the other haem units
- this change increases the affinity for O2 allowing the subsequent O2 molecules to bind easier
- at higher ppO2 the haemoglobin approaches 100% saturation and can’t load anymore causing the curve to plateau
what happens when the HbO2 dissociation curve shifts to the right
- at the same partial pressure of O2, the affinity of Hb for O2 decreases
- more O2 is dissociated from the Hb to the tissues
what happens when the HbO2 dissociation curve shifts to the left
- at the same partial pressure of O2, the affinity of Hb for O2 increases
- more O2 is loaded at lower partial pressures
Why does foetal haemoglobin have a curve shifted to the left
- low ppO2 in the placenta
- shift to left = higher affinity for O2
- more loaded at lower ppO2
why do animals at high altitudes have a curve shifted to left
- low ppO2 in high altitudes
- shift to left = higher affinity for O2
- more loaded at lower ppO2
what is the Bohr effect
- increased respiration = more CO2 which dissolves into the blood and lowers the pH (carbonic acid)
- this changes the quaternary structure of Hb and lowers its affinity for O2 and shifts the curve to the right
differences between tissue fluid and blood plasma
- TF contains no large plasma proteins
- TF contains more CO2 than blood plasma
equation for oxyhaemoglobin?
Hb + 4O2 ⇌ Hb(O2)4
differences between tissue fluid and lymph
- TF contains less WBC’s than lymph
describe the features of the capillaries? (5)
- one endothelial cell thick- short diff pathway
- gaps between endothelial cells (fenestrations) - increase permeability
- many capillaries/highly branched - large surface area
- high total cross-sectional area=more frictional resistance=slower blood flow which allows more time for substance exchange
- small diameter means RBC’s are squeezed against the endothelial wall - short diff pathway
what is haemoglobin made up of?
4 haem units and 4 polypeptide chains ( quaternary protein structure)
- each haem unit can combine with one oxygen molecule so one Hb molecule can transport 4 oxygen molecules
What is venous return?
- skeletal muscles that surround veins contracting and compressing the veins pushing the blood along
