T1 Flashcards
Describe the nature of water.
- Polar molecule due to an unevenly distributed charge.
- Hydrogen end slightly positive and Oxygen end is slightly negative. Hence dipole nature.
What are the 3 main properties of water?
1) Solvent properties.
2) Thermal properties.
3) Very cohesive.
Explain the solvent properties of water.
Chemicals dissolve easily due to dipole nature. Hence, biochemical reactions occur in cytoplasm.
Polar molecules dissolve easily in water and are therefore hydrophilic.
Explain the thermal properties of water.
Water has a very high specific heat capacity; energy required to raise 1g of water by 1 degree is high.
Meaning large amounts of energy is required to break the hydrogen bonds.
What is meant by water being very cohesive and what are the benefits?
Cohesion is the attraction between molecules of the same type.
Given that water has a dipole nature, it is very cohesive so this helps water to flow so it’s great for transporting substances.
What is the transport medium?
All liquids and particles are transported in one direction due to a difference in pressure called mass flow.
What are some of the dissolved substances contained in the plasma (mainly water)?
- Oxygen, Carbon dioxide
- Proteins and amino acids
- Salts
- Enzymes
- Hormones
- Antibodies
- Urea
Define diffusion.
Movement of molecules or ions from a high concentration to a low concentration.
What is an open circulatory system?
1) Heart pumps and blood circulates in large open spaces surrounding organs where it then diffuses between the blood and cells.
2) Heart relaxes and the blood is drawn in from the cavities through small valve openings.
Explain how a Closed circulatory system works.
1) Blood leaves the heart via arteries then arterioles to capillaries.
2) Exchange (diffusion) happens from capillaries to cells.
3) Then the blood returns to the heart via venules then veins.
Animals with a closed circulatory system tend to be larger in size and more active.
What is the purpose of valves?
Prevent blood flowing backwards so all the blood flows in one direction.
Explain how the single circulatory system works.
1) Heart pumps deoxygenated blood to the gills.
2) Gaseous Exchange happens; oxygen diffuses in and carbon dioxide out.
3) Blood leaves the gills and circulates the body
4) Blood returns back to the heart.
E.g. A fish
How does a double circulatory system work?
1) Right ventricle pumps deoxygenated blood to the lungs.
2) It then returns to the heart where the left ventricle pumps the oxygenated blood.
3) It then circulates the body before returning back to the heart.
What are the advantages of a double circulatory system?
1) blood flows through blood vessels which are narrow increasing blood pressure so it’s more efficient.
2) second pressurised pump allows for the oxygenated blood to flow faster around the body allowing for a higher metabolic rate as more nutrients can be rapidly delivered.
3) first pump is slower allowing for a more efficient gaseous exchange.
Explain the different between the left ventricle and the right ventricle?
Left ventricle is thicker with more muscular walls as it needs to pump blood around the whole body.
Right ventricle is smaller as it only needs to pump blood to the lungs with a more effective weak pump so gas Exchange is more effective.
Where are the atrioventricular valves?
They link the atria and ventricles and stop blood flowing backwards into the atria when the ventricles contract.
Where are the semi-lunar valves?
Link the ventricles to the pulmonary arteries and aorta, stopping blood flow back into the heart after the ventricles contract.
What is the basic structure of the heart?
It is made out of cardiac muscle and has 4 chambers with a double pump.
Right side receives deoxygenated blood.
Left side receives oxygenated blood.
What is the structure of arteries?
- Narrow lumen
- Thicker walls
- More collagen, smooth muscles and elastic fibres
- No valves
What is the structure of veins?
- Wide lumen
- Thinner walls
- Fewer collagen, smooth muscles and elastic fibres
- Valves
What is the structure of capillaries?
- Smallest of the blood vessels
- One cell thick
- Branches like a web
What happens during atrial systole?
1) Blood under low pressure flows from left to right atria from pulmonary veins and vena cava.
2) Atria fill opening the atrioventricular valves and then contract allowing blood into ventricles.
What happens in ventricular systole?
1) Ventricles contract increasing pressure in the ventricles.
2) It results in the semi-lunar valves opening.
3) Thus, blood flows through the pulmonary arteries and aorta.
What is Cardiac Diastole?
Both atria and ventricles relax and the elastic recoil of the relaxing heart reduces the pressure.
Coronary arteries fill during diastole. Low pressure in the atria helps draw blood into the heart from the veins.
Explain the process of atherosclerosis.
1) Endothelium with arteries becomes damaged and dysfunctional due to high blood pressure.
2) Inflammatory response occurs and the white blood cells move to the artery wall. Cells accumulate with cholesterol leading to fatty deposits called atheromas.
3) Calcium salts and fibrous tissue build up resulting in hard swelling called plaque. Loss of elasticity and hardens.
4) Plaque results in narrower lumen increasing blood pressure; positive feedback.
How are platelets specialised for their function?
Platelets change from flattened discs to spheres with thin projectiles causing them to stick to exposed collagen of the wall.
This forms a temporary platelet plug and also release of substances that activates more platelets.
