Endocrine Flashcards
Endocrine signalling
Secreted by glands into capillary and has target organs reached by blood
Neuroendocrine signalling
Secreted by nerves into capillary and has target organ reached by blood
Neurotransmitters
Released by axon terminals of neurons into synaptic junctions, act locally
Paracrine signalling
Secreted by cells into Extracellular fluid and effects neighbouring cells of a different type
Autocrine signalling
Secreted by cells into Extracellular fluid and affect function of same cells that produce them
Proteins & polypeptide endocrine molecule structure
Contains 2 amino acids and stored in secretory vesicles until needed
Protein & polypeptide endocrine molecule function by…
- Bind to cell surface receptors and work through G reactive type proteins
- about 75% of SMAs transduced with G-protein coupled receptors
Steroid endocrine molecule structure
- Made from cholesterol, lipid soluble
- needs transport plasma protein to travel through the blood
Steroid endocrine hormones are produced and secreted from…
Adrenal cortex, ovaries, testes, placenta
Steroid hormones function
Signalling occurs through binding to cytoplasmic or nuclear receptors
Derivatives of tyrosine are made in…
Thyroid and adrenal medulla
Thyroid hormones are secreted by the ____
Thyroid
T4 is ____
Thyroxine
T3 is ____
Triiodothyronine
T4 comprises ____ of thyroid hormones
97%
T3 comprises ____ of thyroid hormones
3%
T4 is active/inactive?
Inactive
T3 is active/inactive?
Active
Biochemically, amino acid derivatives function like ____
Steroid
Tyrosine derivatives made in the adrenal medulla are termed ____
Catecholamines
Name the catecholamines
Dopamine, norepinephrine, epinephrine
Catecholamines function like ____
Polypeptide hormones
Name the steps of G-Reactive protein function
- Opens a membrane channel for a specific ion
- Activates cAMP or cGMP
- Activates enzymes
- Activates gene transcription
What happens when G-reactive proteins open an ion-specific channel?
Keeps it open for a longer period of time than is generally seen with a typical ligand-gated channel
What happens when cAMP or cGMP is activated?
Stimulates specific metabolic machinery in the neuron
What happens when enzymes are activated?
Initiates biochemical reactions in target cell
What happens when gene transcription is activated?
Gene transcription & protein synthesis May alter metabolism or morphology of cell
Types of polypeptide growth factors
Mitogens
Trophic factors
Chemoattractants
Function of mitogens
Stimulate cell proliferation (mitosis)
Function of trophic factors
Growth & survival
Function of chemoattractants
Gradient for mobile (WBC) cells (inflammation)
Histamine and nitric oxide are ____
Amines
Histamine location
- made by mast cells with IgE molecules on surface
- located in CT of bronchi & intestines
How does histamine work?
- Allergen causes cross links to form between IgE molecules, Ca enters cell —> histamine released
- Binds to either H1 or H2 receptor
What happens when H1 histamine receptor is activated?
A. Causes venules to vasodilate —> increases tissue swelling & WBC infiltration into tissue
B. Causes release of hypothalamic releasing factors —> increase release of anterior pituitary hormone
What happens when H2 histamine receptor is activated?
Causes release of stomach acid from parietal cells in stomach
Nitric Oxide (NO) works as a…
Localized negative feedback to vasoconstriction
Describe how Nitric Oxide (NO) works
- Arteriole constricts due to E or NE
- Causes release of ACh by endothelial cells, increases Ca influx to endothelial cells
- Turns on enzyme: NO-synthase, converts arginine to citrulline and releases NO
- NO diffuses to smooth muscle cells
- Stimulates smooth muscle light chain phosphatase —> vasodilation
