Download The Endocrine Glands

The Endocrine Glands
SBI 4U
January 10th, 2013
Answer the Following Questions!
Protein hormones are hydrophilic. True
False
2. What are prohormones?
3. How are hormones different from local regulators?
1.
What is the Endocrine System?
 The endocrine system is made up of glands that produce and
secrete hormones
 Hormones regulate body’s growth, metabolism and sexual
development and function
 In charge of body processes that happen slowly
Water vs. Lipid-soluble Mechanisms
 Single target cell may have receptors for several hormones.
Ex: liver cells (insulin & glucagon)
 Hormones can interact with different types of receptors in a
host of cells
Mechanisms by which hormones work
Only cells with receptors respond to hormones
2. Once bound to receptors, hormones produce response by
inactivating or activating cellular processes
3. Hormones effective in very small concentrations
4. Response to a hormone differs among target organs and
among species
1.
Hormones as Feedback Mechanisms
 Secretion of most hormones as a result of negative feedback
mechanisms
 Ex: hypothalamus  thyroid releasing hormone  triggers
pituitary gland to release TSH  triggering thyroid to
release thyroid hormones. Where is the negative feedback?
The Endocrine Glands
 Hypothalamus
 Anterior Pituitary and






Posterior Pituitary
Adrenal glands
Ovaries
Testes
Pineal gland
Thyroid gland
Parathyroid glands
Hypothalamus
 Hypothalamus is a region of the brain  also a part of the




nervous system
Neurohormones: control production of other hormones in
pituitary gland
2 types of neurohormones: releasing hormones & inhibiting
hormones (for anterior pituitary gland)
Other hormones produced for posterior pituitary gland
Controlled by input from nervous system
Pituitary Gland
 Pituitary gland: 2-lobed gland within the cranial cavity that




produces hormones that control the other endocrine glands
“Master gland”  production of hormones controlling most
endocrine glands
Located below brain, within the cranium
Anterior lobe & posterior lobe
Neurohormones travel through portal vein  connecting
hypothalamus to pituitary gland
Anterior Pituitary Gland
 Endocrine system largely controlled by the anterior pituitary





hormones, which are controlled by the hypothalamus
inhibiting or releasing hormones
Regulator hormones like ‘thyroid stimulating hormone’
Ex: Growth hormone (GH)
GH  cell division, protein synthesis, and bone growth
GH binds to muscle, causing the release of insulin-like
growth factor (IGF)
GH also maintains availability of glucose and fatty acids
Deficiencies in GH
Overproduction of GH
 GH binds to muscle, causing the release of insulin-like growth factor (IGF)
 GH also maintains availability of glucose and fatty acids
 Overproduction of GH: pituitary giant
 Deficiency of GH: pituitary dwarf
Posterior Pituitary Gland
 Stores and released 2 hormones: antidiuretic hormone and




oxytocin (both produced in hypothalamus)
ADH: stimulates kidney cells to absorb more water from
urine, increases blood volume
Ethanol and caffeine inhibit ADH
Nicotine and stress stimulate ADH
ADH helps maintain blood pressure by reducing water loss
Posterior Pituitary Gland
 Oxytocin stimulates release of milk from mammary glands
 Also helps in the stimulation of contractions during
childbirth