The Endocrine System

1
The Endocrine System
2
Endocrine Glands

• Endocrine glands release hormones
• Hormones chemicals that circulate through the
  body to regulate the metabolic functions of other
  cells in the body
• The cells affected by a hormone are called its
  target cells
• Target cells must have specific protein
  receptors for the hormone so that the hormone can
  bind and do its job

3
Process of hormone release and action
Stimulus
Desired effect is achieved
Hormone is released
Hormone travels to target cells
Hormone binds to receptor on target cell
4
Hormones we have mentioned in class

• Calcitonin
• Parathyroid hormone (PTH)
• Growth hormone
• Estrogen
• Testosterone
• Epinephrine (adrenalin)
• Erythropoietin

5
Classes of Hormones

• 2 main types
• Steroid (made from cholesterol) - bind directly
  to DNA to exert their effects through
  transcription and translation (ex. Testosterone,
  estrogen, thyroxine)
• Amino acid based (made from amino acids) - bind
  to a receptor on a cells membrane to exert its
  effect via a 2nd messenger molecule (ex. Growth
  hormone, epinephrine, insulin)

6
Endocrine Gland Stimuli

• Neural - nervous system stimulates release of
  hormone
• Humoral - a substance in the blood stimulates
  release of a hormone (ex. PTH and blood calcium)
• Hormonal - a hormone is released for the purpose
  of stimulating another gland to release a hormone

7
Hormonal Blood Sugar Regulation

• Insulin and glucagon (both released from
  pancreas) regulate blood sugar
• Insulin lowers blood sugar if it is too high
• Glucagon raises blood sugar if it is too low
• Carbohydrates stimulate insulin release (fats and
  proteins have little effect on insulin)