Option H - Physiology

Question 0

Define hormone

Answer 0

Hormones are chemical messengers, secreted by endo crine glands directly into the blood. The blood carries them to target cells, where they elicit a response.

Question 1

H.3.4 - List the materials that are not absorbed, but egested

Answer 1

• Cellulose
• Lignin
• Bile pigments
• Bacteria
• Internal cells

Question 2

H.1.1 - State the function of hormones

Answer 2

Hormones are chemical messengers secreted by endocrine glands into the blood and transported to specific target organs

Question 3

H.1.2 - State the different types of hormones

Answer 3

Hormones can be:
Steroids - e.g. testosterone, estrogen
Proteins - e.g. insulin, glucagon
Tyrosine derivatives - e.g. thyroxine

Question 4

H.1.3 - Distinguish between the mode of action of steroid hormones and protein hormones

Answer 4

STEROID HORMONES

• Enter target cells through the plasma membrane (are lipophilic)
• Bind to receptor proteins in the cytoplasm to form a steroid/receptor complex which affects gene expression
• Can act directly as a transcriptional regulator

PROTEIN HORMONES

• Cannot enter target cells (are lipophobic)
• Binds to receptors on the surface of the plasma membrane, which activates second messengers within the cell
• Acts indirectly to change cellular activity (via signal transduction pathways)

Question 5

H.2.1 - State which glands secrete digestive juices

Answer 5

Digestive juices are secreted into the alimentary canal by glands, including:

• Salivary glands
• Gastric glands in the stomach wall
• Pancreatic glands of the pancreas
• Glands in the wall of the small intestine