U3 Endocrine system: Endocrine glands

Question 1

What are the endocrine glands?

Answer 1

• Hypothalamus
• Pituitary gland
• Pineal gland
• Thyroid gland
• Parathyroid glands
• Thymus gland
• Pancreas
• Adrneal glands (adrenal medulla, adrenal cortex)
• Gonads (testes and ovaries)

Question 2

Pineal gland

Answer 2

• Secretes the hormone melatonin
• Influences sexual development and sleep patterns

Question 3

Thyroid gland

Answer 3

Secrets hormones:

Thyroxine
- secreted in response to thyroid stimulating hormone
- maintains body temperature and metabolism
- increased thyroxine = increased metabolic rate
- iodine is needed to make thyroxine

Calcitonin
- regulates the levels of calcium and phosphate in the blood
- increased calcitonin = decreased calcium in the blood
- opposites the action of the parathyroid hormone

Question 4

Parathyroid glands

Answer 4

Secrete parathyroid hormone
- regulates the level of calcium in the blood
- increased parathyroid hormone = increased calcium in the blood

Question 5

Thymus gland

Answer 5

Secretes thymosins
- Influence the production and maturation of T-lymphocytes (T-cells)
- T-lymphocytes help protect the body from infection by fighting diseases

Question 6

Adrenal glands

Answer 6

• There are two adrenal glands, one for each kidney
• Each one has an inner adrenal medulla and an outer adrenal cortex

Adrenal cortex secretes:
Aldosterone
- acts on the kidney to decrease the amount of sodium and increase the amount of possasium in urine
Glucocorticoids (EG: cortisol)
- maintains, metabolism blood pressure and cardiovascular function
- help the body respond to stress by raising blood glucose levels

Adrenal medulla secretes:
Adrenaline and noradrenaline
- Prepares the body for the fight or flight response
- Increases heart rate and breathing rate

Question 7

Pancreas

Answer 7

• Only gland that is both endocrine and exocrine
• Exocrine part secretes digestive enzymes into the small intestine through the pancreatic duct
• Endocrine part involves specialised cells called islets of Langerhans:

Alpha cells:
- release glucagon which stimulates the liver to release glucose stored as glycogen and therefore increased blood glucose levels

Beta cells:
- release insulin which increases the rate at which body cells take up glucose to decrease blood glucose levels

Question 8

Gonads

Answer 8

• Controlled by luteinising hormone and follicle stimulating hormone (gonadotropins) from the anterior pituitary lobe

Ovaries (females)
- secrete hormones estrogen and progesterone which promote the development of female sex characteristics during puberty and encourages fertility

Testes (males)
- secrete testosterone which promotes masculine development

Question 9

What are the two types of glands?

Answer 9

Exocrine glands
- Glands that secrete into a duct that carries the secretion to the body surface or to one of the body cavities
- EG: sweat glands, digestive glands

Endocrine glands
- Glands that secrete hormones directly into adjacent tissue (aka: ductless glands) which then pass into the capillaries to be transported by the blood