Endocrine System - Practice Questions

Question 1

Describe the mode of action of a steroid hormone. (4 marks)

Answer 1

• being lipid soluble it moves easily through the mainly lipid membrane by diffusion
• it enters the cytoplasm and binds with a receptor protein
• the hormone-receptor complex move into the nucleus
• the complex activates genes controlling protein synthesis

Question 2

Describe the mode of action of a amine/protein hormone. (4 marks)

Answer 2

• hormones reaches the target cell but does not pass through the membrane
• hormone attaches to receptor on the membrane of the cell
• the formation of the hormone receptor complex causes a secondary messenger to diffuse through the cell
• this activates particular enzymes

Question 3

Describe the process that stimulates the release of TSH from the pituitary gland. (5 marks)

Answer 3

• hypothalamus is stimulated by low levels of thyroxin in the blood
• hypothalamus produces TSH releasing factors
• which are carries by the blood to the anterior lobe of the pituitary
• TSHRF stimulates the production and release of TSH into the blood
• TSH targets the thyroid causing it to produce and release thyroxin

Question 4

What is the difference between how a protein and steroid hormone enters a cell?

Answer 4

• receptor on cell membrane vs receptor inside cytoplasm
• hormone receptor complex forms on cell membrane vs forms in cytoplasm
• hormone stays outside of cell vs hormone moves through cell
• enzymes activated in the cytoplasm vs genes activated to form a particular protein