Cell to cell communication over a distance, usually through the blood
cell to cell communication between cells in close proximity
cell to cell communication with oneself
Cellular tool for conveying a message. 1. Peptide 2. Amino Acid 3. Steroid
Cell type targeted by a hormone. Must contain or express receptor for hormone
Contained either intracellularly (for steroid) or extracellularly (on the membrane). Must be present to receive the message from the hormone
Protein coded by a gene. Usually made as a pre-pro hormone and modified to active form
Amino Acid Hormone
Made of modified amino acids via enzymes, such as tryptophan to dopamine
Can act intracellularly. Lipophillic and able to diffuse into cell. All are derived from cholesterol, like cortisol, aldosterone, etc
Form complex with some hormones. Allow for generation of a reserve stock of hormone and increases the half-life. Protects from proteases by covering enzyme cut sites. Bigger when in complex = harder to excrete.
Generally have chronic effects
Generally have acute effects. Important for things you want to increase or decrease very quickly.
Metabolic clearance rate
Volume of plasma cleared of the hormone per unit time. Inversely related to Half-life.
Actions of/on secreted hormones
1. Bind a receptor and elicit a response 2. Be metabolically transformed by the liver 3. Undergo urinary excretion
Time it takes for the hormone concentration to decrease by 50%. Inversely related to metabolic clearance rate. Affected by hormone size, glycosylation, binding proteins
Endocrine disorders result from:
1. Hormone concentration alterations 2. Changes in target cell responsiveness
Use of radio-labelled hormone and antibodies to determine hormone concentration. This is done by comparing the amount of radioactivity lost after addition of the sample (which is non-tagged)
Saturation Plot for RIA
Determines exactly how much radioactive hormone you need to saturate a set amount of antibody.
Displacement curve for RIA
Generation of a standard curve by adding known amounts of unlabelled hormone and measuring the decrease in radioactivity.
Determination of hormone concentration (RIA)
Add sample to saturated sample. Measure decrease in saturation, and determine concentration based on your standard curve.
Hypothalamus produces releasing hormone. Releasing hormone causes Pituitary to produce/release a pituitary hormone Pituitary hormone acts on target organ or tissue *Negative feedback inhibits various steps
Target organ (etc) acts on organs 2 or more steps away to the pathway, like target organ causing negative feedback on the hypothalamus, such as cortisol
Feedback that acts one step back, like the pituitary inhibiting the hypothalamus. ACTH is an example
Feedback on self, like oxytocin positive feedback
Regulation of Hypothalamic-Pituitary axis
Neural Hormonal Nutrient
Peptide Hormone expression
Constitutive- Constant vesicle release Regulated- only under certain conditions. Stored.
Constitutive Peptide Hormone
Made and secreted. No storage. Regulation is at level of DNA rather than level of secretion
Regulated Peptide Hormone
Make peptide, send to Golgi to process, package into secretory vesicles, stored until needed
Ligand Binding Domain
Binds hormone.... the listener 1. Cell surface receptors (peptide and AA) 2. Intracellular receptors (steroid and thyroid)