B2 - Mocks
L10 - The Lungs
Order: Mouth/Nose, Trachea, Bronchi, Bronchioles, Alveoli, Capillaries, [Diaphragm].
The purpose of the intercostal muscles is to contract in order to pull the ribcage up and outwards.
The purpose of the diaphragm is to contact in order to increase the volume of the chest.
L11 - Blood
The function of the lungs is to maintain a constant supply of oxygen for cellular respiration (and the removal of waste carbon dioxide).
The lungs ventilate through contraction of the intercostal muscles and the diaphragm, this changes the pressure and causes air to flow in or out of the lungs.
The blood contains plasma (contains CO2 and other waste substances), red blood cells (contain haemoglobin that binds with oxygen), white blood cells (aid the immune system), platelets (clot and form scabs).
L12 - CHD
In CHD, layers of fatty material build up within the coronary artery, causing them to narrow. This reduces the volume of blood that can flow through the arteries at one time so oxygen is provided to the heart muscle (the muscles therefore respire less).
Several issues that can arise relating to the heart include:
- Blocked coronary arteries.
- Heart attacks.
- Faulty valves.
- Hole in the heart.
Stents are a way of treating CHD; they are a mesh that is placed in the artery. A balloon is then inflated within this mesh, this expands the coronary artery; the balloon is then removed. These stents will remain there for a long time and the recovery period is short; there is a chance of infection - however - and a chance of blood clots forming.
CHD can also be treated using statins, they are used to reduce blood cholesterol level and this reduces the rate at which fatty material builds up. These have to be taken regularly - however - and side effects may occur as a result.
Faulty heart valves can be treated through the use of drugs, a mechanical valve replacement or a biological valve replacement.
Biological valves are often salvaged from animals such as pigs; they typically last 8-10 years, produce no 'clicking' noise and do not require anticoagulation drugs to be taken. Mechanical valves typically last > 20 years, but require anti-coagulation drugs to be taken and produce a 'clicking noise'.
L13 - Health Issues
A diet that is high in salt can increase blood pressure; increasing the risk of cardiovascular diseases. Smoking can also increase the likelihood of a person developing a CV disease (such as emphysema).
Carcinogens are substances that increase the risk of cancer due to exposure or ingestion.
People with type two diabetes struggle to maintain a suitable level of glucose within the blood.
A correlation is a pattern within data, if there is a correlation between contracting a disease and a lifestyle factor, this does not identify a direct cause. A causal mechanism is - however - the direct causation or reason for a disease developing.
L14 - Cancer
Cancer is the result of uncontrolled cell division and growth, cancerous tissue is known as a "tumour".
Benign tumours are cancerous tissue that will not break off and form a secondary tumour, they are harmless and can simply be cut off.
Malignant tumours are cancerous tissue that can form secondary tumours due to cancerous cells breaking off, being transported by the blood or lymph system and 'attacking' healthy tissue.
L15 - Plant Tissue
Examples of plant tissue include:
- Spongy mesophyll
- Palisade mesophyll
- Epidermal cells
- Xylem
- Phloem
- Meristem
The spongy mesophyll contains large spaces between cells, this allows for the diffusion of gasses in and out of the cell.
The palisade mesophyll contains a large amount of chloroplasts which are necessary for the palisade cells to perform their function (photosynthesis).
The function of the upper epidermal tissue is to allow for light to pass into the plant and into the palisade cells. The lower epidermis is covered with stomata; stomata are responsible for controlling water loss and gas exchange.
L16 - Transpiration and Translocation
Transpiration is the movement of water inside a plant; this process begins at the root hair cells, with water moving from the roots to the leaf via the xylem and then out the leaf in the form of water vapour form the stomata.
Translocation is the movement of dissolved sugars from the leaves to the rest of the plant, these sugars are stored or used by the plant.
Stomatal Density = Number of observable stomata / Area of sample
L17 - Rate of Transpiration
Water vapour diffuses more easily into dry air as the concentration gradient is steeper.
A higher wind intensity results in water vapour being removed from the leaf more quickly.
Plants can alleviate the rate of water loss via a waxy cuticle or by concentrating their stomata on the underside of leaves.