Parathyroid Gland Hormone

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Parathyroid Gland Hormone

• Parathyroid hormone (PTH)
• Stimulates bone cells to release Ca2 into blood
• Stimulates the activation of vitamin D, which
  promotes Ca2 absorption into the blood from the
  small intestine

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Stimulus rising blood Ca2 level
Thyroid gland
Calcitonin
Reduces Ca2 uptake in kidneys
Stimulates Ca2 deposition in bones
Blood Ca2 declines to set point
Homeostasis
Blood Ca2 rises to set point
Increases Ca2 uptake in intestines
Stimulates Ca2 uptake in kidneys
Stimulates Ca2 release from bone
PTH
Parathyroid glands
Stimulus falling blood Ca2 level
Fig. 40.10, p. 924
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Hormones of the Adrenal Medulla

• Epinephrine and norepinephrine
• Catecholamines
• Reinforce the sympathetic nervous system in
  responding to stress

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Hormones of the Adrenal Cortex

• Glucocorticoids
• Help maintain normal blood glucose levels
• Cortisol (anti-inflammatory)
• Mineralocorticoids
• Regulate Na balance, extracellular fluid volume
• Aldosterone
• Androgens
• Secreted in small amounts

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Low glucose in blood
Epinephrine released in response to stress
or
Hypothalamus
Corticotropin- releasing hormone
Anterior pituitary
Negative feedback pathways
Adrenocorticotropic hormone (ACTH)
Adrenal cortex
Glucocorticoids (cortisol)
Raises blood glucose by stimulating glycogen
breakdown in liver cells Inhibits glucose
uptake by body cells (except in CNS)
Stimulates fat and protein breakdown to release
fatty acids and amino acids
Fig. 40.11, p. 925
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Gonadal Sex Hormones

• Produced in gonads (testes, ovaries)
• Regulate development of reproductive systems,
  sexual characteristics, and mating behavior
• Androgens (anabolic steroids, testosterone)
• Estrogens (estradiol)
• Progestins (progesterone)

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Hormones of Islet of Langerhans Cells of the
Pancreas

• Insulin and glucagon
• Regulate blood glucose levels
• Insulin lowers blood glucose concentration,
  inhibits conversion of noncarbohydrate molecules
  into glucose
• Glucagon raises blood glucose by stimulating
  glycogen, fat, and protein degradation

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High blood glucose
a Cell
ß Cell
Glucagon decreases
Insulin increases
Blood glucose decreases to normal level
Low blood glucose
a Cell
ß Cell
Insulin decreases
Glucagon increases
Blood glucose increases to normal level
Fig. 40.12, p. 927
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Pineal Gland Hormone

• Melatonin
• Interacts with hypothalamus to set the bodys
  daily biorhythms
• In some vertebrates (fish, amphibians, reptiles),
  helps animal change skin color