The larger the surface area of epithelium the faster the rate of absorption is..

Humans don't make enzymes to digest cellulose. Bacteria can digest cellulose in the human intestines, but much of the cellulose eaten is undigested. It is sometimes called 'Fibre'.

Platelets release clotting factors. first in the process of blood clotting.

There is a cascade of reactions in which fibrinogen is converted into fibrin.

Blood clotting seals cuts in the skin. (skin diagrams are not required.)

Some lymphocytes act as memory cells and can quickly reproduce to form a clone of plasma cells if a pathogen carrying a specific antigen is encountered again.
Note: Subgroups of phagocyte and lymphocyte are not required, except these two types of cells derived from lymphocytes.

Describe Florey and Chain’s experiments to test penicillin on bacterial infections in mice.

In March 1940 Chain requested that two mice be injected with a sample of the penicillin.
The mice survived showing that penicillin was not toxic to mice.

Florey then tested the antibacterial properties of penicillin in mice.
Eight mice were injected with hemolytic streptococci (bacteria)

Four of these were subsequently injected with doses of penicillin. Four were untreated.

Less than one day later the four mice that had received penicillin were alive, but the untreated mice were dead.

Further testing involving hundreds of mice was carried out
On August 24, 1940, Florey and Chain reported their findings in the Lancet; as a cure for bacterial disease.

Although neurones release chemical neurotransmitters at their endings they actually transmit electrical impulses along their length. This is caused by movement of charged ions across the membrane, but these ions don't move along the neurone.

Neurotransmitters diffuse across the synaptic cleft and bind to receptors in post synaptic neurones.

After this they can be broken down by enzymes before reabsorption by the presynaptic neurone.

The digestive system moves ingested nutrients by peristalsis, secretes some enzymes and much mucus, digests macromolecules and absorbs nutrients.
While excretion of some chemicals does pass by the digestive system, this is not its main function. Sensitivity is not an important function, nor is storage.

Peristaltic movements cause mixing of the food contents with enzymes and move the digesting food slowly through the intestines.

The blood leaving the small intestine is transported to the liver where digested nutrients such as glucose can be stored as glycogen, but a more important role of the liver in digestion is the production of bile, which is secreted to emulsify lipids to aid their digestion.

Villi absorb monomer products of digestion and small soluble molecules such as vitamins and minerals.
Proteins larger than a few peptides long need to be hydrolysed before they can be absorbed.

Digestive enzymes break the bonds in polymers by adding water - hydrolysis.

Arteries are defined by the direction of flow from the heart, they do have muscular walls but so do veins (even though they are thinner), the pulmonary artery carries deoxygenated blood

The elastic walls of the arteries expand and then contract between contractions of the ventricles, this movement maintains blood pressure between pump cycles.

Epidemiologists study disease to examine causes and consequences which may lead to preventative measures

The raising of the rib cage increases thoracic volume, decreasing pressure, causing air to enter because the pressure in the thorax is lower than atmospheric pressure.

Nodes of Ranvier are found between successive Schwann cells in the myelin sheath. The impulse "jumps" from one node to the next, increasing the speed of transmission.

The right side of the heart generates a low pressure and slow flow rate to allow blood to become oxygenated and to not damage the lung alveoli.

Systole is contraction of a heart chamber, the left ventricle has the highest pressure to pump blood around the systemic (body) circulation.

The pulmonary vein does not need valves because it is short in length and the pressure of blood from the heart retains the flow. The aorta and pulmonary artery have veins to prevent backflow of blood to the heart. The vena cava is the main vein returning blood to the heart from the body and has valves.