Endocrine glands in the body (2)

Question 1

Where is the hypothalamus situated?

Answer 1

The hypothalamus is part of the brain, situated above the pituitary gland.

Question 2

What hormone does the hypothalamus secrete?

Answer 2

It secretes, amongst others, the hormone ADH (anti-diuretic hormone)

Question 3

What is the role of ADH?

Answer 3

The Osmoreceptors hypothalamus detect an increase in the osmolarity (low water levels) of the blood. The hypothalamus responds and releases ADH. ADH helps to conserve water if the body is dehydrated. It does this by causing more water to be reabsorbed back into the blood from the of collecting ducts of the kidney, so less water is lost in urine.

Question 4

What is the pituitary gland?

Answer 4

This gland acts as the chemical co-ordinator of most of the other endocrine glands and is therefore often called the ‘master gland. It is attached to the hypothalamus at the base of the brain by a short stalk.

Question 5

What is the role of TSH?

Answer 5

Thyroid stimulating hormone (TSH), which stimulates the thyroid gland to secrete its hormone, thyroxine.

Question 6

What is the role of FSH? (2)

Answer 6

• Follicle stimulating hormone (FSH) In females FSH stimulates oogenesis in the ovary, i.e. the formation of eggs (ova).
• In males FSH stimulates spermatogenesis in the testes, i.e. sperm formation.

Question 7

What is the role of Luteinizing hormone?

Answer 7

Luteinizing stimulates ovulation (release of an egg) from the ovary and the formation of the corpus luteum.

Question 8

What is the role of Prolactin?

Answer 8

Prolactin, which stimulates the production of milk in the female mammary glands after the birth of the baby. This will continue for as long as the baby sucks. Prolactin is also responsible for much of the maternal instinct.

Question 9

What is the role of Adrenocorticotropic hormone (ACTH)?

Answer 9

ACTH stimulates the adrenal cortex to secrete the hormones, cortisone and aldosterone.

Question 10

What is the role of interstitial cell stimulating hormone (ICSH)?

Answer 10

Interstitial cell stimulating hormone (ICSH), which stimulates the testes to secrete as testosterone.

Question 11

What is the role of growth hormone (GH) (somatotrophic hormone) or STH?

Answer 11

Growth hormone (GH) (somatotrophic hormone), which promotes skeletal and muscular growth. It does this by stimulating the synthesis of proteins.

Question 12

What growth disorders can occur?

Answer 12

Too much or too little growth hormone causes growth disorders.

• hyposecretion = under secretion of a hormone
• hypersecretion= over secretion of a hormone.

Question 13

How does gigantism occur?

Answer 13

In prepubertal (before growth stops) children: hypersecretion of growth hormone results in overdevelopment of the skeleton (tall stature). This condition is known as gigantism.

Question 14

What is gigantism caused by?

Answer 14

This is usually caused by a tumor in the pituitary gland and is extremely rare.

Question 15

What does hyposecretion of growth hormone result in?

Answer 15

hyposecretion of growth hormone results in underdevelopment of the skeleton (short stature).

Question 16

What features do those who suffer from hyposecretion of growth hormone? (3)

Answer 16

• This is known as and has some of the following features.
• Although height is reduced, they can be as short as 91–122 cm, the body proportions of pituitary dwarfism are normal.
• They are not mentally retarded but are often sexually immature.

Question 17

How can hyposecretion be treated?

Answer 17

They can be treated by injections of synthetic growth hormone (STH) produced by genetically engineered bacteria.

Question 18

What does the over-secretion of GH lead to in adults?

Answer 18

In adults, over-secretion of GH leads to a condition called acromegaly, a condition where the bones of the face, hands and feet are enlarged. The thickening of soft tissues leads to enlarged features and an enlarged tongue.