Physiology Flashcards
Name some primary endocrine glands
Parathyroid, pituitary, thyroid, pineal, adrenals, hypothalamus, pancreatic glands
Name some secondary endocrine glands
GI tract, kidney, heart, liver, adipocytes, bone
Are peptide hormones:
- hydro or lipophillic and what does this mean in circulation and when it interacts with membrane
- length?
- where do they come from
- half life
- hydrophilic meaning it doesnt need to bind to plasma protein in circulation but needs to interact with plasma membrane receptors to cross lipid bilayer
- vary in length, TRH is short while FSH and LH are long
- come from hypothalamus, pituitary, pancreases, GI tract
- short half life
Are steroid hormones:
- hydro/ lipophillic
- do they need plasma proteins in circulation and can they cross bilayer
- what are they derived from
- what are their effects mediated by
- lipophillic
- need plasma proteins but can cross bilayer
- derived from cholesterol
- intracellular receptors that bind and act as transcription factors
Examples of peptide, steroid and hormones derived from tyrosine
- peptide: GPCR to glucagon and TKCR to insulin
- steroid: cortisol, aldesterone, androgens
- tyrosine: catecholamines, thyroid hormones from the adrenal medulla
Where are the enzymes that metabolise hormones found
Liver, kidney, blood
What’s are acidophils and basophils
- acidophils include somatrophs and mamotrophs- pink cytoplasm and dark nuclei
- basophils include corticotrophs and thyrotrophs- purple cytoplasm
They are found in the ant pit gland
What are the 4 receptor types
- ligand gated (ionotropic, nAChR)
- GPCR (metabotropic, mAChR)
- catalytic (subfamily of TK, cytokines, when bound is results in protein synthesis, gene transcription)
- nuclear (oestrogen, act as transcription factors)
Types of GPCR and how its inactivated
- alpha, beta, gamma
- alpha regulates GTPase activity, it dissociates from beta and gamma to make GDP
- GTP binds to alpha to hydrolyse GFP + Galpha + Gbetagamma to inactive GPCR
What do Galpha s, i, q, gamma do
-s: stimulates adenyly cyclase to increase cAMP, and PPi, cAMP activates PKA to regulate via phosphorylation eg glucagon, adrenaline, calcitonin receptors
-i: inhibits adenyly cyclase… eg somatostatin, dopamine receptors
-q: stimulates phospholipase C, increase IP3 eg adrenaline, DAG, GnRH receptors
- gamma: alpha q binds to phospholipase C beta after disassociation and takes PIP2 in plasma membrane turning it into gamma which has wide spread effects eg K+ channel, MAPK action, inhibits voltage gated Ca+ channels
Receptor TK example, how is it activated, what does it promote
- IGF1 (acts as dimer)
- enzyme activity activated by hormone binding
- intrinsic TK phosphorylates the receptor which proteins recognise and start to signal gene expression
What are nuclear receptors and what are their types
- meditate effects for steroid and thyroid hormones, bile acids, ligand regulated transcription factors, interact as homo/ heterodimers with DNA sequences in promotor regions
- steroid or non steroid
Steroid vs non steroid nuclear receptors
- examples, diffusion, method of action, mono or heterodimer
- steroid:
Glucocorticoid, mineralcortiocoid, oestrogen
Have plasma membrane receptors so can passively diffuse
Receptor is a monomer but has a chaperone which dissociates when hormone binds (homodimersation) then into nuclear to alter gene expression) - non steroid:
Thyroid hormone receptors nuclear heterodimers with RXR
T4 to T3
Lipophillic so passes through plasma membrane
TR RXR has compressor molecules bound to it which dissociates when T3 binds (co expression)- co activators bind to induce transcription
Hormonal fetal control- insulin, thyroid, glucocorticoids, IGF
- insulin modulates IGF expression and effects differentiations and proliferation in adipose- metabolic, mitogenic
- thyroid help brain: synaptogenesis, growth of dendrites and axons, neuron migration, myelination
- glucocorticoids: help liver and liver surfactant, and intestines and their villi
- IGF2 interuterine growth, paracrine effects, nutrient transfer
- IGF1 regulates growth in relation to nutrients and detects levels
