Transport in Animals Flashcards
(22 cards)
What is tissue fluid?
-Where cells soaked
-To facilitate substance exchange between cells & blood
Name the 2 types of pressure related to the formation of tissue fluid
-Oncotic
-Hydrostatic
What is oncotic pressure?
Tendency of water to move into blood by OSMOSIS
What causes osmotic pressure? Describe how it does this
-Plasma proteins
-Cause diff in ψ between blood & tissue fluid -> osmosis occurs (osmotic effect)
Which type of water has the highest water potential?
Pure water
Explain why oncotic pressure always stays constant. What value is it always?
Plasma proteins can’t leave blood fenestrations (too big)
-Always -3.3kPa
What does a positive and negative oncotic pressure mean?
-Positive: substances move out of blood
-Negative: substances move into blood
What causes hydrostatic pressure within a human?
Heart contractions
State 3 ways CO2 can be transported
-Binds to amino groups -> carbominohaemoglobin (10-20%)
-Dissolved in blood plasma (5%)
-Converted in cytoplasm of red blood cells into hydrogen carbonate ions (75-85%)
What is the Bohr shift?
Hb’s O2 affinity is inversely related to conc of CO2
What is an advantage of the Bohr shift?
-Ensures Hb releases O2 to areas that require it most e.g. respiring tissues
-Ensures CO2 transported to lungs for excretion
Describe the Bohr Shift
-CO2 diffuses into erythrocyte
-CO2 reacts w/ water -> carbonic acid (catalysed by carbonic anhydrase)
-Dissociates into H+ & HCO₃^- ions (hydrogen carbonate)
-HCO₃^- diffuse out erythrocyte -> plasma (lowers pH)
-Cl^- ions diffuse into erythrocyte -> balance charge (chloride shift)
-Haemoglobinic acid maintains pH & removes H+ from cytoplasm
-O2 diffuses out of blood
Explain why haemoglobin has a higher affinity for hydrogen ions than oxygen
H+ ions cause conformational change (change Hb shape)
Compare the levels of oxygen and carbon dioxide in the respiring tissue and lungs
-Respiring tissue: high CO2
-Lungs: high pO2
Explain how oxygen binds to haemoglobin in the lungs
-Lungs: high pO2 -> Hb has higher affinity for O2 than protons
-So proton dissociates from Hb -> Hb binds to O2 -> oxyhaemoglobin
Explain why large organisms cannot have an open system
-No vessels -> low H pressure -> low speed -> reduced conc gradient -> less supply of nutrients e.g. O2 for respiring cells
-Transport blood to diff parts of body
-If had open, would need to rely on body movements so higher metabolic demand needed
-Low SA:V need specialised exchange surface therefore need circulatory system
Describe how the action of the heart is initiated and coordinated
Describe the role of the atrioventricular node in the production of a heartbeat
Passes on electrical IMPULSE from SAN to Bundle of His
Describe the role of the Bundle of His and Purkyne Fibres in the production of a heartbeat
Carry electrical IMPULSE from AVN to ventricles -> contract
Is the fibrous tissue between the atria and the ventricles able to conduct waves of excitation?
No
Describe why without the purkyne tissue, blood would not be pumped out of the heart efficiently
-Conduct wave of excitation
-To apex of heart
-So contraction occurs upwards
-Both ventricles contract together
