Endocrine System Part 2 Flashcards
Hypothalamus
Brain region connected to the pituitary gland via the median eminence
Hormones from the hypothalamus can either stimulate or inhibit the pituitary.
Anterior pituitary
Connected to hypothalamus through specialized blood vessels, Hypothalamo-hypophyseal portal veins
Posterior pituitary
Axons from neurons in the hypothalamus terminate here
Posterior pituitary does NOT SYNTHESIZE its two hormones; it only secretes them
Oxytocin: Milk EJECTION reflex of nursing mothers, emotional bonding
Antidiuretic hormone (ADH/Vasopressin): Regulation of water balance, osmolarity
Distinguish between the roles of prolactin and oxytocin
Prolactin produces milk while oxytocin releases milk
List the 6 anterior pituitary hormones and what they act on.
1) Follicle Stimulating Hormone – FSH
Acts on the gonads and causes germ cell development.
2) Lutenizing Hormone – LH
Acts on the gonads and causes hormone secretion of estradiol and progesterone in females and testosterone in males.
3) Adrenocorticotropic Hormone – ACTH
Acts on the adrenal cortex and causes the release of cortisol.
4) Thyroid stimulating hormone – TSH
Acts on the thyroid and causes the release of T3 and T4.
5) Prolactin
Acts on the breasts and causes breast development and milk production.
6) Growth Hormone – GH
Acts on the liver to secrete IGF-1 and on many other organs and tissues for protein synthesis and carbohydrate and lipid metabolism.
If you see the words “releasing” or “tropic” you know that it comes from the
hypothalamus
______ glands secrete their products into a duct, from where the secretions either exit the body or enter the lumen of another organ.
Exocrine
Endocrine
glands are ductless glands that secrete chemicals into the blood called hormones
Be able to write out a negative feedback loop.
1) Stimulus
2) Hypothalamus- hormone 1 secretion
3) Plasma hormone 1 in hypothalamo-hypophyseal portal vein
4) Anterior pituitary- hormone 2 secretion
5) Plasma hormone 2
6) Third endocrine gland- hormone 3 secretion
7) Plasma hormone 3
8) Target cells of hormone 3- respond to hormone 3
Hypothyroidism
- Congenital
- Iodine deficiency
- Autoimmune - Hashimoto’s disease
Hyperthyroidism
- Tumors
- Autoimmune – Graves’ disease
Actions of Thyroid Hormones
- Metabolic Actions
* Carbohydrate absorption from small intestine
* Fatty acid release from adipocytes
* Cholesterol synthesis
* Gluconeogenesis (glucose synthesis from non-carbohydrate sources)
* Stimulate Na+/K+ ATPases
* Indirectly
-ATP synthesis
-Heat= body temperature - Permissive Actions
Up-regulate beta-adrenergic receptors
-Heart
-Nervous system
* Potentiation
-Increase in SNS effects - Growth and Development
*Promotes synthesis of growth hormone
*CNS effects during development: Axon terminal formation, dendritic spine formation, synapses, myelination
Hypophysiotropic Hormones
The Thyroid Gland
- Secretes thyroid hormones T3 (Triiodothyronine) & T4 (thyroxine)
- Follicles:
Epithelial cells surround colloid
Protein-rich gel-like substance - TRH (Hypothalamus)= TSH (Ant. Pituitary)= T3 & T4
- TSH stimulates
-T3 (active form) & T4 production and secretion
-Hypertrophy of thyroid gland: Increase in DNA synthesis & cell division of follicular cells - Negative feedback
-At hypothalamus - ↓ TRH
-At anterior pituitary - ↓ TSH
