Osmoregulation

The body controls its internal environment. One example of this is control of the concentration of the blood.

Give the name for controlling the internal environment.

Give the name for controlling the concentration of the blood.

A person entering a warm environment may become dehydrated as the concentration of the blood changes. Explain how the concentration of their blood is restored.

A person’s response to a changing environment involves communication by nerves and by hormones. State three differences between communication by nerves and communication by hormones.

The diagram shows a nephron from a human kidney.

Name the structures labelled A, B, C and D.

The nephron produces urine that flows out of tube A to the bladder. Explain how changes in the composition of this liquid are brought about when a person is dehydrated (short of water).

4 (a) Hormones are released during exercise.

Explain the role of adrenaline during exercise.

During exercise, water is lost from the body by sweating. Explain the role of ADH following this loss of water.

The graph shows how level of exercise can affect risk of infection in a person.

Describe the relationship between level of exercise and risk of infection.

It is thought that exercise affects the immune system by reducing the number of white blood cells in the body. Explain how a reduction in the number of white blood cells can affect the risk of infection.

Name the process that maintains a constant internal environment in the body.

The diagram shows a section through human skin.

Explain how part A helps a person to maintain a constant body temperature when they enter a warm place.

Explain how part B helps a person to maintain a constant body temperature when they enter a warm place.

The body controls the water content of the blood.

Name this process.

Name the organ that controls the water content of the blood.

The diagram shows a kidney nephron with parts labelled A, B and C.

The table lists events that take place in the nephron. Complete the table by giving the letter of the part where each event takes place.

The photograph shows a flower called a dandelion.

If a person picks this flower and then licks their fingers, they will want to urinate. This is because the plant produces a chemical called a diuretic that affects the regulation of the water content of the blood. Suggest how this diuretic causes more urine to be produced.

The photograph shows an Arabian oryx.

Arabian oryx live in the desert where there is no free-standing water. Most of their habitat is sand. Plants, such as grass and small trees, cover only a small area. Oryx feed mainly on grass. Summers are hot. Daytime temperatures can be as high as 41 °C and temperatures at night only fall to 24 °C. Oryx are less active in summer than in winter. In summer, they reduce their energy use by changing their behaviour and body processes.

Suggest why oryx are less active in summer than in winter.

In summer, oryx rest under trees during the day and feed at night. Suggest why they do this.

Suggest where the oryx get their water from in the absence of free-standing water.

Oryx and humans can control water loss by making their urine very concentrated. Describe how this is done.

The skin is an organ of homeostasis and excretion.

Describe what is meant by the term excretion.

The diagram shows a section through the skin with two structures labelled A and B.

The structures labelled A and B play a part in homeostasis when a person enters a very warm environment.

Explain the role of structure A.

Explain the role of structure B.

Some hormones are involved in homeostasis.

Explain the role of insulin in homeostasis.

Explain the role of ADH in homeostasis.