Adrenal Glands (6)

Question 1

What is an adrenal gland and where is the adrenal gland?

Answer 1

A pyramid-shaped adrenal gland is found on the top end of each kidney. Each adrenal gland is made up of two glands, the inner medulla and outer cortex.

Question 2

What is the adrenal cortex?

Answer 2

The adrenal cortex secretes a group of steroid (fat-based) hormones, i.e. aldosterone, cortisone and reproductive hormones. Their functions are varied but very important.

Question 3

What is aldosterone?

Answer 3

Aldosterone causes increased reabsorption of sodium ions from the filtrate in the kidney nephrons and the simultaneous movement of potassium ions into the filtrate. It therefore helps to regulate the electrolytic levels of body fluids and is therefore vital for osmoregulation.

Question 4

What is cortisol?

Answer 4

Cortisol (cortisone) increases the body’s ability to resist stress of all kinds. It is also anti-inflammatory and anti-allergic.

Question 5

What is the adrenal medulla?

Answer 5

The medulla secretes one of the best-known hormones, adrenaline.

Question 6

What are the effects of adrenaline?

Answer 6

Adrenaline, the ‘fight or flight hormone’, is secreted under situations of sudden danger or excitement and will prepare the body for action so it can cope with the emergency.

Question 7

Adrenaline causes the same effects as the sympathetic nervous system to bring about the following effects: (5)

Answer 7

1. Blood pressure increased because vasoconstriction (narrowing of blood vessels) takes place in the skin and alimentary canal. This enables more blood to go to the skeletal and cardiac muscle where it is needed.
2. The blood sugar levels are increased because liver glycogen is converted to glucose. The glucose is released into the blood stream and will provide fuel for the release of extra energy.
3. The oxygen content of the blood is raised because the breathing rate and depth of breathing is increased. Rate ‘because breathing muscles are stimulated and ‘depth’ because the bronchial tubes dilate. The extra oxygen is needed for increased respiration which results in more energy being released.
4. The heart rate is increased. This results in more blood with higher levels of glucose and oxygen going to the muscles. Cellular respiration therefore increases in the muscle cells and more energy is made available for muscle activity.
5. Skeletal muscle-tone is increased enabling the muscles to respond more quickly.

Question 8

What are other effects of adrenaline? (4)

Answer 8

• Dilation of pupils for better vision in the emergency.
• Increased sweating for increased cooling of the body when being physically active.
• Reduction of digestive system activity.
• Increased mental alertness to be aware and think about how to cope with the emergency.