L15. Hormones

Question 1

Relationship between the hypothalamus and pituitary gland

Answer 1

• both work together to regulate endocrine secretion
• hypothalamus is connected to the pituitary gland by a “stalk”
• pituitary gland gets its order from the hypothalamus

Question 2

2 types of pituitary glands

Answer 2

ANTERIOR PITUITARY: communicates via hormones

POSTERIOR PITUITARY: communicates via neurons

Question 3

Anterior pituitary

Answer 3

• communicates via hormones
• separate tissue and separate organ
• makes and releases own hormone when the hypothalamus tells it to

Question 4

Posterior pituitary

Answer 4

• communicates via neurons
• made out of the same tissue as the hypothalamus
• storage place for two hormones (oxytocin and antidiuretic) from the hypothalamus and release it when the hypothalamus tells it to

Question 5

Hypothalamic tropic hormones

Answer 5

Tropic hormones tell another gland to release its hormones:

• GHRH: Growth hormone releasing hormone
• GnRH: Gonadotropin releasing hormone
• TRH: Thyrotropin releasing hormone
• CRH: Corticotropin releasing hormone
• PRH: Prolactin releasing hormone

Question 6

Hypothalamic inhibitory hormone

Answer 6

• PIH: Prolactin inhibitory hormone

- GHIH: Somatostatin

Question 7

Anterior pituitary gland hormones

Answer 7

Produces and secretes:

• HGH: human growth hormone > bone and muscle
• TSH: thyroid stimulating hormone > thyroid
• FSH: Follicle stimulating hormone (gonadotropin) > testis
• LH: Luteinising hormone (gonadotropin) > ovary
• PRL: Prolactin > breast
• ACTH: Adenocorticotrophic hormone > adrenial cortex

Question 8

Feedback system of Thyroid hormone

Answer 8

1. Hypothalamus releases TRH (Thyrotropin releasing hormone) which acts on the anterior pituitary gland
2. Anterior pituitary gland releases TSH (Thyroid stimulating hormone) which acts on the thyroid gland
3. Thyroid gland releases TH into the blood stream
4. TH acts on target tissue
5. Abundance of TH in the blood feeds back into anterior pituitary gland to stop releasing TSH (via neg feedback)
6. Feeds back into the hypothalamus to stop releasing TRH

Question 9

Positive feedback

Answer 9

The stimulus and the reaction amplify each other

Question 10

Positive feedback in childbirth

Answer 10

1. head of fetus pushes against cervix
2. nerve impulses from cervix transmitted to brain
3. brain stimulates pituitary gland to secrete oxytocin
4. oxytocin stimulates uterine contractions and pushes fetus towards cervix

Question 11

Oxytocin (OT)

Answer 11

• stored in the posterior pituitary gland
• affects uterus, mammary glands > stimulates smooth muscle contractions
  eg. labour and milk secretion, promote affection/ bonding

Question 12

Antidiuretic hormone (ADH)

Answer 12

• stored in the posterior pituitary gland

- affects the kidneys > promotes water retention

Question 13

Adrenal medulla hormones

Answer 13

• release epinephrine (adrenaline) and norepinephrine (noradrenaline)
• sympathetic nervous system stimulation- “fight or flight”
• increase alertness, anxiety, fear, prepares the body for physical activity

Question 14

Blood calcium homeostasis

Answer 14

• if the blood calcium goes down, your parathyroid gland will release parathyroid hormone
• this makes the osteoclasts break down the bone and put the calcium back into the blood to restore homeostasis
• if the calcium levels are too high, then thyroid gland will release calcitonin
• calcitonin will cause osteoblast to deposit bone so the blood calcium levels go back to normal

Question 15

The pancreas

Answer 15

Has endocrine and exocrine functions:

• exocrine: digestive juices
• endocrine: hormones

GLUCAGON

• released between meals, while fasting
• promotes release of glucose, gluconeogenesis, glycogenolysis, break down of fats to increase blood glucose

INSULIN

• released after you’ve eaten a meal
• stimulates cells to absorb glucose, muscles and adipose tissue to store glycogen and fat, decrease glucise