3.3.2 Mass Transport Flashcards
Define a closed circulatory system
Blood is enclosed within vessels/diffusion of substances only takes place within vessels
Define a single circulatory system
Blood flows through the heart once for each complete circuit of the body
Blood is pumped at a low blood pressure. Suitable for organisms with a low metabolic rate
Define a double circulatory system
Blood flows through the heart twice for each complete circuit of the body (i.e simultaneously pumps to lungs and heart)
Maintains a high blood pressure to meet demands of a high metabolic rate
Why cant complex multi cellular organisms rely on diffusion to transport substances around the body?
They have a small SA:vol so can’t diffuse substances quickly or efficiently enough to reach all the cells
Why is a closed circulatory system more efficient?
The blood is forced through fairly narrow tubes so it remains under pressuse and therefore travels faster, delivering oxygen and glucose to cells more quickly
Describe the structure of capillaries
Very narrow lumen for short diffusion distance, single layer of cells so it can lie very close to the cells
What is the function of the capillaries?
Where metabolic exchange occurs so substances are exchanged between cells and the blood
Describe how blood flows in veins
Blood flow is assisted by the contraction of skeletal muscles during movement of limbs and breathing.
State the four chambers of the heart
Left atria/left ventricle/right atria/right ventricle
State the four vessels entering/exiting the heart
aorta/vena cava/pulmonary artery/pulmonary vein
How is the left side of the heart identified?
Presence of a thicker muscular wall
What is present inside the heart to prevent backflow?
AV valves (tricuspid = right, bicuspid = left) and semi-lunar valves.
Why are the ventricle walls thicker than atria walls?
Blood needs to be under higher pressure to travel a further distance
Why are valves important?
Prevent backflow/allow build up of pressure
State what happens to the heart during ventricular diastole and atrial systole
Ventricles are relaxed/atria contract/increases pressure in atria/AV valves open/blood flows into ventricles
How does the structure of xylem allow them to transport water?
Hollow as no cytoplasm, vessels have no end walls and pits, vessels are strong so do not collapse, lignin makes the walls waterproof
How does no ATP production affect transport of substances in plants?
translocation inhibited but transpiration stream not inhibited. Phloem contains cytoplasm but xylem does not. Cytoplasm has mitochondria involved in metabolism.
State the function of xylem vessels
Transport water and mineral ions up the plant and provide support
State the function of phloem tissue?
Transport organic solutes from where they are made in the plant to where they are needed
Describe the structure of xylem tissue
Long tube-like structures formed from dead cells joined end to end, found together in bundles. Hollow lumen as no cytoplasm and no end walls makes an uninterrupted tube allowing water and mineral ions to pass through the middle easily. Walls thickened with lignin.
Describe the structure of phloem tissue
Sieve tube elements (living cells) joined end to end to form sieve tubes. Sieve parts are the end walls which have lots of holes to allow solutes to pass through. There is a companion cell for every sieve tube element
Why do plants need water?
For photosynthesis, to transport minerals, maintain structural rigidity and to regulate temperature
Why do plants need nitrate ions?
For production of DNA, proteins and chlorophyll. They are required for plant growth, fruit production and seed production
If the CO2 concentration increases, which way will the oxygen dissociation curve shift?
To the right - haemoglobin will have a lower affinity and will unload more easily
If the CO2 concentraiton decreases, which way will the oxygen dissociation curve shift?
To the left - haemoglobin will have a higher affinity and will load more easily
During diastole, which valves are open and which are closed?
semi lunar closed, AV valves open
During ventricular systole, which valves are open and closed?
AV valves close, semi-lunar valves open
State how the oxygen affinity of haemoglobin changes in a high concentration of CO2 vs a low concentration of CO2. Explain why this is useful for humans.
Haemoglobin has a high oxygen affinity in high in low CO2 concentration and a low affinity in high CO2 concentration. This means oxygen is loaded at the lungs (where CO2 conc is low) and unloaded at the respiring cells (where CO2 conc is high)
Give the basic structure and function of arteries, veins and capillaries
describe what happens to heart muscle, the blood in the heart and the valves in: atrial systole, ventricular systole, diastole
Describe the mas flow hypothesis
