Lec 05 Flashcards
Hormones secretion
From endocrine tissue or glands
Properties of Hormone
1-Cell-to-cell communication
2-Binding to target receptor initiate cellular response
3-Communication is eventually terminated
4-Half life= time for hormone conc. To decrease by 1/2
Cell-to-cell communication hormones
1- chemical signals
2- transport by blood to distant targets
Hormones communication eventually is terminated
1-limiting secretion
2-removing/inactivating hormone
3-terminate target cell activity
Hormone classified based in:
1- source
2- receptor
3- chemical structure
4- function
Peptide vs protein hormone
Peptide is smaller
Protein is larger
Peptide/protein hormones
1- made in endocrine cells
2- made in advance(preprohormone: large ,inactive with 1 or more copies of final peptide) and stored in vesicles
3- PREPROHORMONE—PROHORMONE—HORMONE(series of post-translational modifications)
4- Final hormone is active
5- Released into ECF by Exocytosis
6- Diffuses from ECF into blood
7- Half-life is short
8- Lipophilic—bind membrane receptors
9- Active secondary messenger
10- Response: altered activity of target proteins
Steroid hormones are made by demand
Memorize
Steroid hormones
-made from cholesterol
-made in adrenal glands,kidney,skin,gonads,placenta
-final hormone is lipophilic-CANNOT BE STORED
-made in SER
Smooth ER functions
1- store Ca ion
2- synthesis steroid hormones
Peptide hormone example
Insulin
Glucagon
Steroid hormones example
Sex hormones
Steroid hormone movement
1- Simple diffusion into blood (due to lipophilic)
2- bound to carrier protein in blood (have longer half time)
3- intracellular receptors: cytosolic/nuclear — regulation of gene activity — slow response
4- membrane receptors: fast response
Amine hormones
-Made in pineal gland, adrenal medulla,thyroid
-derived from tyrosine
-CATECHOLAMINES(Neurohormones)AND THYROID
Catecholamine
Characteristics similar to peptide hormones
-lipophobic
-stored for release
-short half time
Thyroid hormones
Characteristics similar to thyroid hormone
-lipophilic
-made on demand
-requires carrier protein
-long half life
-genomic response
Exocrine vs Endocrine glands
Secretory cells may be scattered among other epithelial tissue cells
Endocrine glands
Connecting cells disappears
Blood vessels are must
Ex, insulin, oxytocin
Exocrine glands
Ex. From pancreas to small intestine
Sweat glands
Oil glands
Pancreas
Dual function— endocrine and exocrine
Endocrine Pancreas
1-Alpha cells — secrete glucagon
2-Betta cells — secrete insulin
Exocrine pancreas
Acinar cellls and duct cells
Hormones may regulate
1- rate of enzymatic reaction
2- transport of ions across cell membrane
3- gene expression or protein synthesis
Cellular mechanism depends on
1- presence and location of target cells
2- specific signaling pathways
Pituitary gland
Two glands fuse together
-posterior pituitary is neural tissue
-anterior pituitary is endocrine tissue
Posterior pituitary gland
extension of Neural tissue
Secret neurohormones
Ex. Oxytocin
Anterior pituitary
Endocrine gland of epithelial origin
Secrete six hormones
Hypothalamus
Controls the release of hormones from anterior pituitary by neurohormones
Posterior pituitary gland secrete
1- neurohormone is made and packaged in cell body
2- vesicles transported down the cell to posterior pituitary gland
3- vesicles exocytosis
4- vesicles of neurohormones are stored in posterior pituitary
4- neurohormones are released to blood
Anterior pituitary gland secrete:
1- hypothalamic neurons synthesize neurohormones and release them into capillaries of the portal system
2- portal veins carry neurohormone directly to anterior pituitary, act as endocrine cells
3- endocrine cells release peptide hormones
Anterior pituitary gland example
TRH from hypothalamus
TSH from anterior pituitary
TSH stimulate thyroid production int thyroid gland
