Unit 6.6 and Unit D5 - Hormones

Question 1

What is the structure of the pituitary gland?

Answer 1

• contains an anterior and posterior lobe.
• connected to the hypothalamus
• apart of the brain
• is an endocrine gland, releasing hormones such as oxytocin (posterior) and FSH (anterior).

Question 2

Difference between posterior and anterior lobe in pituitary gland?

Answer 2

Anterior:
- Signal transmitted from hypothalamus, causing a release factor to be secreted and travels down a portal vessel to where the endocrine glands are, causing hormones to be produced. (ADENOHYPOPHYSIS)
- i.e. FSH/LH
Posterior:
- Signal transmitted from hypothalamus down neurosecretory cell causing a hormone to be released into the blood stream.
- i.e. ADH/Oxytocin

Question 3

Explain the differences in steroid hormones and peptide hormones.

Answer 3

Steroid hormones:
- Non-polar, so they can diffuse through the plasma membrane of a cell
- Binds with a steroid-hormone receptor, this then moves into the nucleus of a cell where it directly affects DNA transcription and gene expression
- i.e. testosterone

Peptide hormones:
- Polar, so they cannot diffuse through the plasma membrane of a cell, so they bind to cell membrane receptor proteins
- This causes secondary messengers - like cyclic AMP - to transduce the signal of the hormone to the nucleus, where cellular activity is activated or deactivated.
- i.e. ADH

Question 4

What does growth hormone do to the human body and why is there a ban in sports?

Answer 4

• Reduce the amount of adipose tissue formed
• Increase the amount of muscle tissue formed
• Can give an unfair advantage due to its potential performance enhancement
• But, it is difficult to detect as it is a naturally occurring hormone.

Question 5

Explain how glucagon and insulin regulate blood glucose levels

Answer 5

glucagon, produced by alpha cells in the pancreas, breaks down glycogen stored in the liver and in the adipose tissue (through glycogenolysis) into monomers to increase blood glucose levels are low. When blood glucose levels are high, insulin is secreted by beta cells in the pancreas where monomers are turned into glycogen through glycogenesis and stored in the liver or adipose tissue.

Question 6

What is thyroxin?

Answer 6

It is a hormone secreted by the thyroid gland in response to signals in the hypothalamus. it controls basal metabolic rate of all cells. it also is responsible for the temperature the body is retained at.

Question 7

What is leptin?

Answer 7

Leptin is a hormone secreted by adipose tissue and regulates fat stores by suppressing hunger levels. It affects the hypothalamus.

Question 8

What is melatonin

Answer 8

Melatonin is a hormone secreted by the pineal gland in response to changes in light. It is mainly used in ensuring the circadian rhythm of an individual - the routine in which a person sleeps and wakes up.