3.1.2 Transport in Animals Flashcards
Multicellular organisms
High metabolic demand
SA:V low
Open circulatory system (insects)
Blood NOT inside vessels
Low metabolism
Closed circulatory system (fish and mammals)
Blood within the vessels
Pumped by heart
Higher metabolism
Single circulatory system (fish)
One circuit
Low metabolic rate still sufficient
Double circulatory system (mammals)
Pulmonary (lungs)
Systemic (body)
Higher metabolism
Higher pressure
Arteries
Narrow lumen Thick elastic layer Thick muscle layer Thin outer layer High elasticity
Veins
Wide lumen Thin elastic layer Thin muscle layer Thick tough outer layer Low elasticity
Transporting O2 and CO2; erythrocytes
Biconcave shape
High surface area
Haemoglobin
O2 binds loosely to iron containing haem group
Hb + 4O2 Hb(O2)4
Transporting O2 and CO2 in the blood
See diagram
The blood
Transports:O2,CO2,digested food, hormones,platelets, antibodies
Maintain:steady body temp,buffer - minimise pH changes
Blood plasma
Glucose, amino acids, mineral ions, hormones, plasma proteins, red and white bc, platelets
55% of blood volume
Tissue fluid
Everything except large plasma proteins
Plasma proteins have oncotic effect so H2O has a tendency to more into the blood from fluid
Oncotic pressure
The tendency of H2O to move into the blood
Around -3.3kPa
Hydrostatic pressure
Blood under pressure from surge of blood when the heart contracts
Around 4.6kPa
When h.s pressure high: H2O moves out
When h.s pressure low: H2O moves in
Lymph
Blood plasma ultrafiltrated into tissue fluid.
Tissue fluid drains into lymph
The cardiac cycle
DEOXYGENATED
RA in vena cava - AV valve open - RV - RA contract - AV closes - RV contract - semilunar valve - pulmonary artery - lungs
OXYGENATED
LA in pulmonary vein - LA contracts - LV contracts - semilunar - aorta - body
Transporting O2/CO2
CO2
—> 5% in plasma as H2CO3
—> 10% in cell as carbamino-haemoglobin (CO2+HbNH2)
—> 85% in plasma as HCO3-
i) CO2+H2O–>H2CO3
ii) H2CO3–>H++HCO3-
For CO2=opposite
How heart action is initiated and coordinated
• Electrical excitation starts at SAN - atria contract
(A layer of non-conducting tissue prevents it passing directly to ventricles)
- AVN picks it up and imposed delay before stimulating bundle of His (purkyne fibres)
- branches at apex where conduction begins = efficient emptying
ECGs
See book
Positive cooperativity
Once one oxygen binds to haem group, the molecule changes shape, making is easier for the next oxygen molecules to bind
What does the oxygen dissociation curve show?
Shows the affinity of haemoglobin for oxygen
Oxygen dissociation curve
Small change in partial pressure of oxygen in surroundings makes significant difference to saturation of the haemoglobin with oxygen
Pattern of oxygen dissociation curve as partial pressure of oxygen increases
- at low pO2: few haem groups bound to oxygen, so haemoglobin doesn’t carry as much
- at higher pO2: more haem groups bound to oxygen, making is easier for oxygen to be picked up
- haemoglobin becomes saturated at v high pO2 as all haem groups become bound
Effect of CO2 on oxygen dissociation curve
BOHR SHIFT
As pCO2 rises, haemoglobin gives up oxygen more easily
As a result:
• active tissues w high pCO2, haemoglobin gives up O2 more easily
• lunge w low pCO2, oxygen binds to the haemoglobin molecules easily
Transporting carbon dioxide
- 5% dissolved in blood plasma
- 10-20% A’s carbaminohaemoglobin
- 75-85% hydrogen carbonate ions in cytoplasm of red blood cells
CO2+H2OH2CO3H++HCO3-
