Introduction to the Endocrine System Flashcards
Autocrine
Paracrine
Endocrine
Neuroendocrine
- secretion affects self or cell of similar type
- secretion affects neighbor cell
- secretion affects target further away (via bloodstream)
- Neuron itself releases secretion into bloodstream
What are special endocrine cells and hormones?
Some cells are within organs (like adipose, heart etc.) and release hormones
-some hormones get converted in the bloodstream (e.g. angiotensin II and vitamin D)
Draw out what hormones the hypothalamus, anterior, posterior pituitary, thyroid and parathyroid glands release
Ok
Draw out the products of the various endocrine glands
Ok
Properties of peptide/protein hormones
Protein is >100 amino acids long
Water soluble
Membrane receptor
Stored in vesicles
Properties of steroid hormones
Precursor is cholesterol
Lipid soluble
Nuclear receptors
Properties of amine hormones
Derived from tyrosine (can be water or lipid soluble)
Describe how protein/peptide hormones are created
Preprohormone (not functional) > ER (turned to prohormone) > vesicle packing and release > cleaved to functional hormone
How are hormones released from storage?
Intracellular Ca2+ increase > cAMP and PKA activation > vesicles with hormone released into bloodstream
Structure of the steroid hormones
4 rings structure (like cholesterol)
Modified side chains
Which glands produce steroid hormones?
Adrenal cortex, gonads, Placenta, corpus luteum
*AC and reproductive organs
What are the two groups of amine hormones?
Catecholamines
Thyroid hormones
What are the properties of catecholamines? What hormones are catecholamines?
- made in cytosol granules. Targets are on membrane
- Epinephrine/norepinephrine and dopamine
What are the properties of thyroid hormones?
- stored in gland lumen as thyroglobulin
- target nuclear receptors
Broadly,at what level are hormones regulated?
Synthesis, secretion or circulation
How does hormone protein binding correlate with hormone half life?
Higher binding = higher half life = lower clearance rate
What is the significance of binding proteins?
Most hormones are bound to binding proteins and are inactive/ Just have to detach from binding protein to activate. Serve as reservoir for when active hormones are depleted.
How exactly can you regulate hormone secretion?
Neural control (neuron instructs release of hormone) Feedback control (product comes back and + or - release of more hormone)
What is positive feedback?
Hormone product comes back and tells maker to make more. Usually leads to explosive event like ovulation or childbirth
What is negative feedback?
Hormone product comes back and tells maker to stop making more hormones (balancing levels)
What is long loop feedback?
3rd tier feeds back to 1st and 2nd tier (e.g. thyroid gland feeds back to hypothalamus and pituitary)
What is short loop feedback?
2nd tier feeds back to first tier (TSH feeds back to hypothalamus)
What is ultra short loop feedback?
Gland inhibits itself
Draw the 5 major endocrine axes (include the tiers)
Ok
What are the regulators of hypothalamus activity?
Suprachiasmatic nucleus
Pineal gland
Physiological stress
How does the suprachiasmatic nucleus work?
It receives info from various parts of the body about day and night info and tells hypothalamus what to do using this info
How does the pineal gland regulate the hypothalamus?
Pineal releases melatonin. This feedbacks to SCN (tells it it’s night time, hypothalamus do night time things!)
How can hormones be regulated using their receptors
- Changing (up/downregulation) the number of receptors (if too much hormone, decrease the receptors to not overwhelm the system. If too little hormone, increase the receptors to increase the chance hormones bind and do its effect)
- Changing the affinity of receptor to hormone
Draw the adenylyl cyclase pathway
Ok
What hormones use the adenylyl cyclase pathway?
ACTH, LH, FSH, TSH, glucagon, ADH (v2 receptor), HCG, CRH, calcitonin, PTH, beta receptors
Draw the mechanism of action of PLC pathway
Ok
What hormones use the PLC pathway?
GnRH, TRH, oxytocin, GHRH, Angiotensin II, ADH (v1 receptor), alpha 1 receptors
Describe the mechanism of action of steroid hormones
Ok
What hormones use the steroid hormone mechanism?
All the hormones released by AC, vitamin D and thyroid hormones
What type of receptors does the guanylyl cyclase pathway use
- ANP (extracellular domain receptor, GC is membrane bound)
- NO (intracellular domain receptor, GC is soluble)
What hormones use the guanylate cyclase mechanism?
ANP
NO
Draw the mechanism of the guanylyl cyclase pathway
Ok
What is the difference between receptor tyrosine kinase and tyrosine kinase-associated receptors?
Receptor tyrosine has its own tyrosine kinase activity
Tyrosine kinase associated receptor associates with a second protein that has kinase activity
> > > > both result in downstream phosphorylation
What hormones use the tyrosine kinase mechanism?
Insulin, IGF-1, growth hormone, prolactin
Review the table of hormone functions
Ok
