Hormones

Question 1

what are Endocrine glands

Answer 1

Endocrine glands secrete hormones directly into the bloodstream

Question 2

describe the mode of action of steroid hormones

Answer 2

diffuse across the plasma membrane
bind to receptors in the cytoplasm
form a receptor-hormone complex
activated complex moves into the nucleus and acts as a transcription factor promoting transcription of specific genes
steroid hormones include: estrogen, progesterone and testosterone

Question 3

describe the mode of action of peptide hormones

Answer 3

• hydrophylic so they cannot freely cross the plasma membrane
• bind to receptors on the surface of the cell
• binding triggers a cascade of reactions
• mediated by second messengers
  such as cAMP
• Peptide hormones include insulin, glucagon

Question 4

Outline the function of hormones in the production and release of milk

Answer 4

Prolactin

• Produced by the anterior pituitary
• Stimulates mammary glands to grow
• Stimulates the production of milk

Oxytocin

• Produced in neurosecretory cells «in hypothalamus»
  OR
  secreted by posterior pituitary
• nursing ( suckling infant) stimulates oxytocin release (stimulation of sensory receptors in the breast )
• IT triggers the release of milk from the mammary glands

Question 5

Outline the need for iodine in human endocrine system.

Answer 5

• iodine is needed by the thyroid
• to synthesise thyroxin
• thyroxin used to regulate metabolic rate/generate heat
• lack of iodine causes swelling of thyroid gland/goiter

Question 6

What hormones are released by the anterior pituitary gland

Answer 6

FSH
LH
Prolactin

Question 7

Which hormones are released by the posterior pituitary gland?

Answer 7

ADH
Oxytocin

Question 8

List 3 steroid hormones

Answer 8

Estrogen
Testosterone
Progesterone