endocrine system

Question 1

what hormone does the hypothalamus secrete and what does it control

Answer 1

• antidiuretic hormone
  -Target organ: Kidney
  •-Controls the concentration of
  water in the blood

Question 2

what hormone does the thyroid secrete and what does it control

Answer 2

• thyroxin

- basic metabolic rate

Question 3

what 2 hormones are secreted by the adrenal gland and what do they control.

Answer 3

-Adrenalin 
Increases:
• heartbeat
• blood pressure
• conversion from glycogen to
glucose
• blood supply to the cardiac
and skeletal muscles
• skeletal muscle tone
• rate and depth of breathing
• diameter of pupils
Decreases:
• blood flow to the digestive
system and skin
Aldosterone
• Target organ: Kidney
• Regulates salt concentration
in the blood

Question 4

what hormone does the Pituitary gland (hypophysis) secrete and what does it control

Answer 4

GH (growth hormone)
• Controls growth
TSH (thyroid stimulating
hormone)
• Stimulates thyroid gland to
secrete thyroxin
Reproductive hormones:
FSH, LH and prolactin

Question 5

what hormone does the what hormone does the Pituitary gland (hypophysis) secrete and what does it control secrete and what does it control

Answer 5

Glucagon
• Stimulates conversion
of glycogen to glucose
(increases blood glucose
levels)
Insulin
• Stimulates conversion of
glucose to glycogen (reduces
the blood glucose levels)

Question 6

what is the General sequence of events in a

negative feedback mechanism

Answer 6

Step 1: An imbalance is detected.
Step 2: A control centre is stimulated.
Step 3: Control centre responds.
Step 4: Message sent to target organ/s.
Step 5: The target organ responds.
Step 6: It opposes/reverses the imbalance.
Step 7: Balance is restored.

Question 7

explain the negative feedback system when there is too much thyroxin in the blood

Answer 7

step 1: increase of thyroxin levels above normal limits
step 2: the pituitary gland is stimulated.
step 3: it secretes less TSH
step 4: the thyroid gland is stimulated
step 5: the thyroid secretes less thyroxin
step 6: the thyroxin levels decrese
step 7: balance is restored.

Question 8

how is the body”s temperature regulated

Answer 8

Body temperature is regulated by the hypothalamus in the brain and the
blood vessels and sweat glands in the skin.

Question 9

what is vasodilation

Answer 9

when the blood vessels become wider due to the heat on a hot day

Question 10

Describe how vasoconstriction mentioned in

question 2 decreases heat loss.

Answer 10

Less blood flows to the surface of the skin.
• Less heat is lost from the surface of the skin.
• Less blood flows to the sweat glands.
• Sweat glands release less sweat.
• Less evaporation of sweat.
• Less cooling of the skin on a cold day.