Endocrinology Flashcards
what is a gland ?
A specialized group of cells or organ that secretes substances to be used or eliminated from the body
What does the endocrine system do ?
A major regulatory system which uses hormones to produce homeostatic adjustments
What are the 6 main functions of the endocrine system
1) maintain constant internal environment through the regulation of metabolism and H2O and electrolyte balance
2) acts as an adaptive stress response
3) used for growth and development
4) reproduction
5) creation of red blood cells
6) integrates with the autonomic nervous system in regulating both circulation and digestion
What is a hydrophilic hormone ?
Is water soluble and have low lipid solubility and carry molecules within the plasma
most hydrophilic hormones are usually what types?
peptide hormones ( short amino acid chain or hormones) OR amines which are hormones based on single amino acid residues
What are the 2 types of amine hormones ?
Catecholamines and thyroid hormones
Hormone synthesis step 1
large precursor called preprohormones are synthesized by endoplasmic reticulum ribosomes
step 2 Packaging
preprohormones are processed into active hormones as they travel through ER and Golgi complex. Preprohormones are packaged into secretory vesicles
step 3 storage
hormone containing secretory vesicles are stored until cell receives appropriate signal
step 4 Secretion
Appropriate signal initiates exocytosis of the vesicles and the hormones are released into the blood
what are lipophilic hormones ?
highly soluble in lipids but poor in water and require a carrier molecule for transport in the body (amine thyroid and steroid hormones
All steroid hormones are synthesized from ?
cholesterol molecule
steroid and thyroid hormones are bound to ?
are bound to carrier molecules or proteins
for hormones to achieve their desired effect they need to be ?
in an an unbound form to interact with target cell ( this is easy for catecholamines and hydrophilic hormones )
- lipophilic hormones require carrier molecules
Peptide hormones and catecholamines bind to specific receptors located ?
located on the outer surface of plasma membrane of their target cells ( can’t cross through lipid bilayer )
Steroid and thyroid hormones are lipophilic meaning they can do what ?
they can cross the plasma membrane and they can bind to receptors inside the target cells
What happens after the binding to the receptor ? (peptide and catecholamines )
they. bind to surface receptors which activates secondary messenger systems in the cell and the initial signal gets amplified as low concentrations of hormone trigger response
What happens when cAMP acts as a secondary messenger ? ( 4 steps)
1) extracellular messenger binds to a receptor activating G protein
2) Triggers the activation of adenyl cyclase molecules
3) activated proteins convert many molecules of ATP + (cAMP which activates protein kinase A
4) Activated kinase A enzyme phosphorylate and activate target proteins
What happens when Ca 2+ acts as a secondary messenger ? ( 4 steps )
1) extracellular messenger binds to a receptor activating a G protein
2) this triggers several Phosphlipase C enzymes which convert PIP2 to IP3 and DAG
3) intracellular Ca2+ activates calmodulin
4) Ca 2+ camodulin complexes then activateCa 2+ dependent protein kinase ( caM kinase), which phosphorylate and activate target proteins
Steps in lipophilic hormones and protein synthesis ( 6 steps )
1) lipophilic hormones diffuse across the plasma membrane and or the nuclear membrane to interact with intracellular receptors
2) hormone receptor complex (H-R) binds to the hormone response element within the DNA
3) DNA binding activates specific genes and produces messenger RNA ( mRNA )
4) mRNA leaves the nucleus
5) mRNA binds to a ribosome and proteins are synthesized
6) These newly synthesized proteins ultimately lead to the cellular response of the hormone
What are the 4 major differences between neurotransmitter and hormones ?
1) Neurotransmitters belong to the nervous system while hormones area central component of the endocrine system
2) Neurotransmitters are transmitted across synaptic cleft , while hormones are transported through blood
3) Hormones are produced by endocrine glands while neurotransmitters are produced by neurons
4) Neurotransmitters travel shorter distances while may travel much greater distances
Neural control response time vs endocrine control
Neural control is rapid while endocrine control is slow
Duration of effects of neural control vs endocrine control
neural control has brief effects while endocrine effects persist long after stimulus
number of targets of of neural control vs endocrine control
neural control is hard wired to one specific gland or muscle while endocrine has many different targets in tj body
