3.2 Transport in animals Flashcards
What are the 3 features circulatory systems have in common?
- they have a liquid transport medium that circulates around the body
- they have vessels that carry the transport medium
- they have a pumping mechanism to move the fluid around the system
What are the 4 types of circulatory system?
- Open circulatory system
- Closed circulatory system
- Single closed circulatory system
- Double closed circulatory system
What is an open circulatory system?
there are very few vessels to contain the transport medium and it is pumped straight from the heart into the haemocoel. found mainly in invertebrates
What is insect blood called?
Haemolymph
What is a closed circulatory system?
The blood is enclosed in blood vessels and does not come directly into contact with the cells of the body
What is a single closed circulatory system and where are they found?
- the blood flows through the heart and is pumped out to travel all around the body before returning to the heart. The blood only travels once through the heart for each complete circulation of the body
- found in fish and annelid worms
What is a double closed circulatory system?
involves two separate circulations. Blood is pumped to the lungs to pick up O and unload CO2 and then returns to the heart where it is then transported all over the body. The blood travels twice through the heart for each circuit of the body
What do arteries do?
Carry blood away from the heart
What do arterioles do?
link the arteries and the capillaries
What are capillaries?
microscopic blood vessels that link the arterioles with the venules
How are capillaries adapted for their role?
- provide a large surface area
- the total cross-sectional area of the capillaries is always greater than the arteriole supplying them so the rate of blood flow falls giving more time for gas exchange
- the walls are a single endothelial cell thick
What do veins do?
carry blood towards the heart
What does the pulmonary vein do?
carry oxygenated blood from the lungs to the heart
What does the inferior vena cava do?
carry deoxygenated blood from the lower parts of the body back to the heart
What does the superior vena cava do?
carry deoxygenated blood from the head and upper parts of the body back to the heart
Do veins have a pulse?
no
What do venules do?
link the capillaries with the veins
What does blood consist of?
- plasma
- red blood cells
- white blood cells
- platelets
What are the functions of the blood?
- transport of O2 and CO2
- transport of digested food
- transport of nitrogenous waste products
- transport of hormones
- transport of platelets to damaged areas
- transport of cells and antibodies involved in the immune response
- maintenance of body temperature and pH
What is tissue fluid?
the solution surrounding the cells of most tissues, arriving via blood capillaries and being removed by the lymphatic vessels
How is filtration pressure calculated?
filtration pressure = hydrostatic pressure - oncotic pressure
Define oncotic pressure
The tendency of water to move into the blood by osmosis
Define hydrostatic pressure
As the blood flows through the arterioles into the capillaries, it is still under pressure from the surge of blood that occurs every time the heart contracts. this is hydrostatic pressure
Does tissue fluid have the same composition as plasma?
no it has almost the same but without red blood cells and plasma proteins
What is lymph?
Tissue fluid that drains into the lymphatic system
Does lymph have the same composition as tissue fluid and plasma?
No, similar but with less oxygen and fewer nutrients. It also contains fatty acids
What is a major role of the lymphatic system?
defence mechanisms of the body
How is oxygen transported around the body?
In haemoglobin in erythrocytes
What is formed when oxygen binds to haemoglobin?
oxyhaemoglobin
What is positive cooperativity?
the arrangement of the haemoglobin molecule means that as soon as one oxygen binds to a haem group, the molecule changes shape, making it easier for the next oxygen molecules to bind
What is plotted in an oxygen dissociation curve?
percentage saturation haemoglobin is plotted against the partial pressure of oxygen
What happens at low pO2?
few haem groups are bound to oxygen so haemoglobin does not carry much oxygen
What happens at higher pO2?
more haem groups are bound to oxygen, making it easier for more oxygen to be picked up
What happens at very high pO2?
haemoglobin becomes saturated so all the haem groups become bound
