Endo: Hormones/Receptors Flashcards
In the endocrine system, hormones are released into _______________ and act on _________ cells
In the endocrine system, hormones are released into the blood and act on distant cells
Compare paracrine, autocrine, and endocrine signaling
(released into…, target cell)
- Paracrine: effector released into extracellular space (acts on nearby cell)
- Autocrine: effector released into extracellular space (target is itself)
- Endocrine: effector released into blood (acts on distant cell)
Is a chemical inherently endocrine, autocrine, or paracrine signaling?
NO. One chemical can act as a hormone, neurotransmitter, etc.
Whether a molecule is endocrine, autocrine, or paracrine depends on how it gets to the target cell
How are water soluble hormones stored/released?
Why?
- Water soluble hormones are stored in vesicles
- Increased intracellular Calcium causes fusion of vesicles and release of hormone
- aka Calcium-dependent exocytosis
- This system is used because water-soluble hormones can’t easily cross the cell membrane to get out into the blood
What 2 kinds of hormones are water soluble?
Protein/peptide hormones
catecholamines
How are steroid hormones stored/released?
- Steroid hormones have minimal storage b/c they are lipids (can’t hang out in cytoplasm)
- Steroid hormones diffuse across cell membrane to reach blood stream
Steroid hormones are ____philic and derivatives of __________
Steroid hormones are lipophilic and derivatives of cholesterol
Compare how steroid and water-soluble hormones travel through blood stream
How does this affect their half life?
- Water soluble hormones float freely in blood
- Protein/peptide hormones thus have shorter half life b/c exposed to proteases
- Steroid hormones are bound to proteins in blood
- Longer half life
Which is more relevant: total hormone level or free hormone level?
Even though the majority of steroid hormones exist bound to protein, only the free hormone has a physiologic effect
So, the amount of free hormone is what we care about
Water soluble hormones bind to __________receptors.
Name the 3 receptor types
- Water soluble hormones bind to cell surface receptors
- Receptors can be
- GPCR’s
- Cytokine receptor family
- EGR-R
What is the effect of the 3 different GPCR’s?
- Gs -> activates adenylate cyclase -> increases cAMP
- Gi -> inhibits adenylate cyclase -> decreases cAMP
- Gq -> activates PLC -> increases IP3, DAG
What 2 water-soluble hormones use cytokine receptors?
What is the effect of cytokine receptors?
- Cytokine receptors used by GH, PRL
- Receptor binding -> Activates JAK (a kinase) -> STAT signaling -> increases transcription
Name one hormone that uses EGF-Receptors
What is the effect of activating EGF-Receptors?
- Insulin uses EGF-R
- EGF-R activates its inherent tyrosine kinase activity and dimerizes
What happens when a steroid hormone reaches its target cell (4)?
- Steroid hormone diffuses across cell membrane
- Steroid hormone binds to receptor in cytoplasm
- Steroid hormone/receptor complex moves into nucleus
- Steroid hormone alters transcription
Is the effect of steroid hormones long-term or short-term?
What about water soluble hormones?
- Steroid hormones exert long-term effects by altering transcription
- Water soluble hormones exert short-terms effects by activating ready pathways
Compare bioassay and immunoassay
- Both are used to measure protein hormone levels
- Bioassay measures activity of hormone as a surrogate for how much hormone is present
- Immunoassay directly measures amount of hormone present, but doesn’t assess functionality
How do we measure the level of steroid hormones?
Because so much of the hormone is bound, it is difficult to measure hormone directly.
So, we measure the amount of a downstream hormone that responds to our hormone of interest
