L68 Endocrinology Basics Flashcards
What are characteristics of classical endocrine glands
Ductless
Secrete into bloodstream/EC space
entire organ dedicated primariy to endocrine function
What are non classical endocrine organs and what do they secrete?
Brain/Hypothalamus: releasing hormones Kidney: Renin, Vitamin D, EPO Heart: ANP, BNP Liver: IGF-1 GI: Stomach: Serotonin, Ghrelin Adipose: Leptin
What are the 3 mechanisms of hormone action?
Endocrine: secrete into blood to act on downstream target tissues
Paracrine: secrete into interstitial space and act on nearby cells
Autocrine: secrete into interstitial space and act back on same cell
What type of signaling is neurotransmitter transmission?
Paracrine
How do hormone binding proteins affect hormone half lives?
They increase it by binding hormones in blodo to facilitate transport
Which hormones use hormone binding proteins?
Steroid hormones (lipophilic) IGF-1, GF, T4/T3
What hormones do SHBG (sex hormone binding globulin) bind?
Estrogen and TEstosterone
What hormones do CBG (Corticotrophin binding protein) bind?
Cortisol/Corticosterone
What hormones do TBG ad TTR (Thyroid Binding Globulin and Transthyretin) bind?
Thyroid hormones
Which hormones are considered bioavailable?
Free/Unbound and Albumiin bound hormones
Which hormones are considered free?
Unbound/free
What role does albumin play in hormone transport in blood?
Binds nonspecifically to lipophilic hormones in blood
How is hormone delivered to atarget cell?
- Steroid hormone released at membrane -> cross lipid bilayer-> intracellular target
- Hormone/Protein complex binds to MEGALIN -> Form endocytic vesicle-> hormone dissociates and is released from vesicle
What is required for hormones to elicit their effects?
Receptors
What is the difference between specificity and affinity?
specificity: ability to distinguish between similar substances (Ki: ability to displace ligand at 50% of max activity=> smaller ki->higher specificity)
Affinity: binding affinity (Kd: ligand concentration that takes up 50% of binding sites; smaller number-> higher affinity)