Transport in Animals Flashcards
why are specialised transport systems needed in animals?
- High metabolic demands
- Small SA:V ratio
- Transport of molecules, food and waste products
What are the 2 types of circulatory systems?
Open and closed
What are the features of an open circulatory system?
- Blood comes into direct contact with cells
- Few vessels
What’s a haemocoel?
Body cavity of an animals
What organisms are open circulatory systems mainly found in?
Insects
What are the features of a closed circulatory system?
- Blood is enclosed in blood vessels
- Blood doesn’t come into direct contact with cells
What organisms are closed circulatory systems mainly found in?
Fish/mammals
What are the 2 types of closed circulatory system?
Single and double
How does a single closed circulatory system work?
Blood only travels through the heart once in every circuit around the body
Give an example of an organism that has a single closed circulatory system
Fish
Which organisms use a double closed circulatory system?
Most mammals
Explain the 2 circulations in a double closed circulatory system?
- Blood travels through the heart twice per circuit
- Oxygenated around body
- Deoxygenated to lungs
What is the name of the circulation that carries blood to the lungs in a double closed circulatory system?
Pulmonary circulation
What is the name of the circulation that carries blood to the rest of the body in a double closed circulatory system?
Systemic circulation
When O2 binds loosely to haemoglobin, what forms?
Oxyhaemoglobin
Write the balanced equation for haemoglobin binding to oxygen
Hb + 4O₂ Hb(O₂)₄
Explain the process of oxygen binding to haemoglobin
- Erythrocytes enter capillaries in the lungs
- Oxygen from alveoli diffuses into erythrocyte and binds to Hb
- Positive cooperativity occurs
- Steep diffusion gradient is maintained until all the Hb is saturated with O2
What is positive cooperativity?
The previous O2 molecule gives an increased affinity for the next one
What is affinity?
How easy Hb is able to associate with O2
What does saturated refer to?
the number of O2 molecules associated with Hb
How does Hb release O2?
- Conc of O2 in cytoplasm is lower than in erythrocyte
- O2 diffuses out of erythrocyte
- Once first molecule is released, Hb changes shape to give easier removal of further molecules
What is plotted on an O2 dissociation curve?
- Percentage saturation
- Partial pressure of O2
What are the units for partial pressure of O2?
PO₂/kPa
Explain the oxygen dissociation curve
- Low affinity for 1st O2 molecule at low pressure
- As pressure increases so does affinity (positive cooperativity)
- At highest pressure, most binding sites are occupied so no more O2 molecules can bind
What is the Bohr effect?
As the partial pressure of CO2 rises, Hb gives up O2 more easily
Where does a foetus get its O2 from?
Oxygenated mother blood in placenta
Why does fetal Hb have a higher O2 affinity?
To associate the necessary O2 from the mother blood in placenta
What percentage of CO2 is dissolved in plasma?
5%
What percentage of CO2 takes the form of carbaminohaemoglobin?
10-20%
What percentage of Co2 is stored as HCO3- in cytoplasm of RBC?
75-85%
What does H2CO3 dissociate into?
H+ ion and HCO3- ion
How is CO2 converted into H2CO3?
By the enzyme carbonic anhydrase
How is H+ removed?
Buffers, especially Hb
What happens to the H+ ion?
- Binds allosterically to Hb
- Changed Hb tertiary structure (dissociates from O2)
- Forms haemoglobinic acid
What happens to the hydrogen carbonate ion?
- Diffuses out of the RBC to maintain a conc gradient so CO2 continually diffuses into RBC
What is chloride shift?
HCO3- ions diffuse out of RBC and are replaced by CL- ions from plasma to balance loss of negative charge
