QUIZ - Hormones and Homeostasis

Question 1

Compare and contrast steroid and peptide hormones.

Answer 1

Steroid
- Non - Polar
- Bind to receptor proteins in the cytoplasm; forms a receptor-hormone complex
- Changes gene expression directly
- Slow onset but longer duration

Peptide
- Polar
- Bind to receptors in the plasma membrane of the target cell
- Activates a signal via second messenger systems
- Fast changes in protein activity

Question 2

What is the role of the hypothalamus in hormonal secretion?

Answer 2

Controls hormonal secretions by the anterior and posterior pituitary

Question 3

List examples of ANTERIOR pituitary hormones.

Answer 3

TSH, FSH, LH, Prolactin, and Growth hormone.

Question 4

Target cells and function of TSH.

Answer 4

• Thyroid-stimulating hormone
• Targets cells of the thyroid to make and secrete thyroxine

Question 5

Target cells and function of FSH.

Answer 5

• Follice-stimulating hormone
• Targets gonads in males and females
  M : meiosis of spermocytes
  F : maturation of oocyte

Question 6

Target Cells and Function of LH.

Answer 6

• Luteinizing hormone
• Targets gonads in M/F
  M : causes leydig cells to make testosterone
  F : causes ovulation of oocyte

Question 7

Target cells and function of Prolactin.

Answer 7

• Targets cells of the mammary glands causing them to grow / produce milk

Question 8

Direct and indirect targets and effects/ actions of Growth hormone.

Answer 8

Direct : adipose tissue (reduces it)
Indirect : Muscles/bones
- Activates IGF (insulin growth factor) in liver which increases bone growth / muscle mass

Question 9

Target cells and function of ADH.

Answer 9

• Targets cells of the kidney, increasing the amount of water that is reabsorbed into the blood

Question 10

Target cells and function of Oxytocin.

Answer 10

• Produced in neurosecretory cells in hypothalamus but stored in/ secreted from posterior pituitary
• Targets cells of the uterine muscles / mammary glands, causing contractions (for birth) / milk secretion

Question 11

Examples of posterior pituitary hormones.

Answer 11

ADH and Oxytocin

Question 12

Explain the roles of the hypothalamus and thyroid gland in thermoregulation.

Answer 12

• Body temp is regulated by thyroxin (elevates metabolic rate = heat)
• Thermoreceptors in skin send signal to hypothalamus
  Too cold
• Hypothalamus sends TSH to anterior pituitary to release TRH -> thyroxin
  Too hot
• Hypothalamus inhibits production of thyroxin
• Lowers body temp
• Negative feedback

Question 13

Explain the role of thyroxin and the causes and consequences of thyroxin deficiency.

Answer 13

• Thyroxin increases basal metabolic rate (production of heat – helps to control body temperature)
• By stimulating carb and lipid metabolism via oxidation of glucose / fatty acids
  Cause: deficiency of iodine
  Consequence: Enlarged thyroid (goiter)

Question 14

Explain the role of melatonin in circadian rhythms.

Answer 14

• Circadian rhythms = body’s physiological response to the 24 hour day-night cycle
• Melatonin regulates circadian rhythms
• Photoreceptors (eyes) send signals to the hypothalamus
• Melatonin secreted by the pineal gland (brain)
• Melatonin release is inhibited by light (lvls high at night)
• High levels of melatonin promote sleep

Question 15

Explain the causes and treatments of jet-lag.

Answer 15

Cause: The body’s inability to rapidly adjust to a new time zone due to extended air travel
Consequence: Taking melatonin during sleeping time of the new time zone

Question 16

Compare and contrast hormonal and nervous communication (in the body).

Answer 16

• BOTH used for communication between all parts of the body
• BOTH can stimulate or inhibit processes in target cells
• BOTH use negative feedback
• BOTH cause a response/change in target cells
  H = chemical messenger, N = Nerve impulse
  H = transported in blood, N = transported by neurons