Endocrine Concepts Flashcards
paracrines
secreted by cells into ECF and affect neighboring target cells that are different than themselves.
Autocrine
secreted by cells into ECF and affect same cells (self)
cytokines
can be autocrine, paracrine, or endocrine hormones
Classes of Hormones:
Polypeptides and proteins
- produced on ER
- preprohormones, cleaved to become prohormones
- Golgi apparatus for packaging into secretory vesicles and exocytosis, usually caused by increase in Ca++
Classes of Hormones”
Steroids
- synthesized from cholesterol
- they are NOT stored
- lipid soluble
- three cyclohexyl rings and one cyclopentyl ring
- large amounts of cholesterol in vesicles ready to mobilize
Classes of Hormones:
Amine Hormones
- derived from Tyrosine
- Adrenal medulla hormones
- epi and NE formed in medulla of adrenals
- 4x more Epi than NE
- stored in vesicles until release by exocytosis
Classes of Hormones:
Thyroid hormones
- Synthesized and stored in thyroid gland
- With globulins which split and form the free hormones
- Then they bind to plasma proteins which release the hormone to target tissues
- protein binding acts as reservoir
Feedback loops
- Long feedback- hypothalamus to anterior pituitary to target organ and the target organ sends a message back to shut down.
- Short feedback- hypothalamus to anterior pituitary and back to hypothalamus
- Ultra short feedback- stays in hypothalamus
What hormone is the only hormone with positive feedback?
Leutenizing Hormone
Types of cyclical variation
- Periodic- monthly
- diurnal- daily
- seasonal
Which types of hormones are water soluble and transported dissolved in plasma
peptides
catechols
Which types of hormones are transported bound to plasma protein
steroid
thyroid
Which hormones bind to a receptor on the surface of the cell membrane?
proteins
catechols
Which hormones bind to the target cell receptor in the cell cytoplasm
steroids
Which hormone binds at the target cell receptor cite in the cell nucleus?
thyroid
How are receptors regulated?
- increased hormone concentration will cause a down regulation of receptors
- caused by inactivation of some of the receptor molecules
- inactivation of some of the intracellular protein signalingmolecules
- temporary sequestration of the receptor to the inside of the cell, away from the site of action
- destruction of receptors by lysosomes
- decreased production of receptors
Enzyme linked hormones
- Hormone binds to the outside of an enzyme
- catalytic binding site on inside
- enzyme is activated (sometimes inactivated) by hormone binding.
Intracellular hormones and activation of genes
- lipid soluble hormones (such as steroid, thyroid, etc bind to receptors inside the cell instead of on membrane.
- once hormone has activated the hormone receptor complex, it binds directly to DNA and activates or represses transcription.
- **thyroid hormones activate directly with receptors in nucleus and increase metabolic activi
Types of second messengers
cAMP
Calcium and associated Calmodulin
products of membrane phospholipid breakdown
How does the Ca++ calmodulin system work?
- Calcium enters cell (by ligand or changing membrane potential.)
- Calcium ions bind with calmodulin
- Calmodulin changes shape and activates or inhibits protein kinases
***Ca/calmodulin system is a 2nd messenger
Gq
Phospholipase C Examples
(IP3)
- Gonadotropin releasing hormone
- thyrotropin releasing hormone
- growth hormone releasing hormone
- corticotropin releasing hormone
- angiotensin II
- Antidiuretic hormone (V1 receptor)
- Oxytocin
- Alpha- Andrenergic agonists
Going to go carefully agains all other advice.
Adenylyl Cyclase
(cAMP) examples
- Adrenocorticotrophic hormone
- leutenizing hormone
- follicle stimulating hormone
- ADH (V2 receptor)
- parathyroid hormone
- calcitonin
- glucagon
- B-Andrenergic agonists
Autumn leaves falling and preparing christmas gifts beautifully
G Protein coupled recepts
IP3
- Ligand attaches to receptor on G protein
- Alpha portion of G protein is released and activates Phospholipase C
- Phospholipase C liberates diacycglycerol (DAG) and IP3 from membrane lipids.
- IP3 mobilizes Ca++ from the endoplasmic reticulum
- The Ca++ and diacycglycerol (DAG) activate protein kinase C which phosphorylates proteins and causes specific physiologic actions
Cytoplasmic/Nuclear Receptor (mostly steriods)
examples
taking steriods can give you “roid rage” so *insert NY accent*… PETTA Can Curse (dirty..)
- P - progesterone
- E - Estradiol (estrogen)
- T - Testosterone
- T - Thyroid horomones (t3/t4)
- A- Aldosterone
- Can - Cortisol
- Curse (dirty) - Calcitrol (vit D)
Tyrosine Kinase
examples
“Tyrone kindly explained that he likes to be ‘in da sun’.. says it helps him grow”
“in da sun” = Insulin
” likes” = IGFs (insulin-like growth factors)
“grow” = Growth horomones
Guanalyate Cylase
examples
“Another Bad Night Out in GUAM”
(all vasodialators:)
- Another = ANP
- Bad = BNP
- Night Out = Nitric Oxide
- in GUAM= sounds like guanalyate
