Hormones & the endocrine system

Animals produce coordinated responses when there are changes to their internal or external environments.

An animal’s nervous system is important in coordinating responses.

Put a tick (✓) next to any statements that correctly describe the functions of parts of an animal’s

Hormones are responsible for coordinating longer lasting responses.

Describe how low thyroxine levels would stimulate a response by the body.

Use the words in the list within your answer.

hypothalamus pituitary gland TRH TSH

* IVF is a treatment some people use when they have difficulty getting pregnant.

This treatment involves the use of hormones involved in the menstrual cycle and eggs being fertilised by sperm in a laboratory.

Embryos are then transferred into a female’s uterus.

This treatment has different results depending on age:

• females under 35 have a 32% success rate

• females aged 40–42 have an 11% success rate.

Name the hormones which are used in IVF treatment and explain their function. Evaluate the effectiveness of using IVF treatment.

Doctors can test your eye reflexes by touching the eye to make you blink. Fig. 14.1 shows the reflex arc involved in blinking.

Fig. 14.1

Explain how the components of the nervous system produce the response of blinking. Use Fig. 14.1.

The endocrine system also controls the body.

Which endocrine gland releases thyroxine into the blood?

Describe two effects of adrenaline on the human body.

Hormones are used in the contraceptive pill.

Explain how the progesterone contraceptive pill prevents pregnancy.

Identify hormone Y.

Explain why hormone X is glucagon.

Compare the functions of glucagon and hormone Y.

Draw lines to connect the letters, X, Y and Z, to the correct name of each neurone.

The foot steps on a sharp object. The leg is pulled away from the sharp object.

Explain how the reflex arc in the diagram produces this response.

The body is also controlled by the endocrine system.

Adrenaline and thyroxine are both hormones.

Compare the roles of adrenaline and thyroxine in the body.

A scientist investigates the effect of glucose on insulin levels in the blood.

They drink glucose dissolved in water. They then measure the level of insulin in their blood.

The table shows their results.

Explain the change in blood insulin levels between 90 and 120 minutes.

This question is about hormones.

The hormone thyroxine helps to control the amount of energy available to cells.

Look at the diagram. It shows how energy levels in the body are controlled.

Explain why controlling energy levels is an example of negative feedback.

Which of these is not an effect of adrenaline on the body?

A Air passages of the lungs expand

B Blood flow to the digestive system increases

C Blood pressure increases

D Pupils dilate