9- chemical control in mammals

Question 1

hormones

Answer 1

Hormones are proteins secreted by the endocrine gland . They are transported in the body by dissolving in blood plasma. They have their effect on target organs

Question 2

adrenal gland

Answer 2

• hormone: adrenaline
• target organ: vital organs etc liver and heart
• effect: increases heart rate and breathing rate

Question 3

pancreas

Answer 3

• hormone: insulin
• target organ: liver
• effect: liver cells convert glucose to glycogen

Question 4

pituitary gland

Answer 4

• hormone: ADH
• target organ: kidney (collecting duct)
• effect: controls blood water levels by triggering the reabsorption of water in the kidneys

Question 5

testes

Answer 5

• hormone: testosterone
• target organ: many
• effect: secondary sexual characteristics, sperm production

Question 6

thyroid

Answer 6

• hormone: thyroxine
• target organ: whole body
• effect: increases metabolic rate

Question 7

modes of hormone action- interaction with receptors

Answer 7

• Hormones bind to external receptor sites.
• The binding activates a G protein.
• The activated G protein activates adenylyl cyclase.
• Adenylyl cyclase catalyses the conversion of ATP to CAMP, the secondary messenger.
• CAMP activates protein kinase.
• Protein kinase phosphorylates proteins in the cytoplasm.
• This activates the proteins, allowing them to alter cell activity.

Question 8

examples of interaction with receptors

Answer 8

• Adrenaline.
• Peptide hormones (polar) which can’t pass through the cell membrane.

Question 9

modes of hormone action- direct entry into cells

Answer 9

• Hormones pass through the cell membrane.
• They bind to a receptor in the cytoplasm.
• The receptor-steroid complex enters the nucleus.
• The receptor-steroid complex binds to a receptor on DNA.
• DNA is transcribed and translated to form a polypeptide.

Question 10

examples of direct entry into cells

Answer 10

• Oestrogen.
• Steroid hormones (lipid soluble) which have a longer effect.