Endocrinology introduction Flashcards
Classify the hormones and give examples of each
3 main classes
- Steroids
- testosterone, estrogen, and progesterone from gonads
- cortisol and aldosterone from adrenal cortex - Tyrosine-derivatives (are all neurotransmitters)
- dopamine/prolactin inhibitory factor from hypothalamus
- T3 and T4 from thyroid gland
- Epinephrine and norepinephrine from adrenal medulla - Proteins/Peptides
- Thyroid stimulating hormone
- LH
- FSH
Glands that secrete only peptides
Pancreas
Parathyroid glands
Anterior pituitary gland
Posterior pituitary gland
Glands that secrete both peptides and tyrosine-derivatives
Adrenal gland
Thyroid gland (T3 and T4 are amines, but calcitonin is a peptide)
Hypothalamus
Leptin is released by? Its function is to?
released by adipocytes. suppresses appetite and stimulates thermogenesis
Two hormones secreted by small intestine and their functions.
Secretin (makes pancreatic acinar cells release water and bicarbonate)
Cholecystokinin (makes gallbladder to contract = release of pancreatic enzyme)
Name the hormone that increases red blood cell production and its source
Erythropoietin - from kidneys
Hormone released by the heart
Atrial natriuretic peptide
Function of atrial natriuretic peptide.
Increases sodium excretion by kidneys
Causes reduction in blood pressure
Name the hormones secreted by placenta and classify them based on their chemical structure.
Estrogen
Progesterone
(steroids)
Human chorionic gonadotropin
Human somatomammotropin
(peptides)
General structure of steroids
3 cyclohexyl rings
2 cyclopentyl rings
Protein that T3 and T4 bind to in plasma
thyroxine-binding globulin
Which tyrosine-derivative of the adrenal medulla is secreted more than the other
Epinephrine secreted 4 times more than norepinephrine
*THINK: NO! = less secretion
Hormones vary based on
how long it takes for them to have an effect
how long their effect lasts
Give the unit range in which hormones exist in blood
from less than 1 picogram (one millionth of one millionth of a gram) to few micrograms (millionths of one gram) in 1 millimeter of blood
LH’s effect on estrogen is an example of what type of regulation? explain
+ve feedback
estrogen causes surge in LH
LH in turn increases estrogen secretion
Ways in which hormones are cleared from blood
Destroyed by tissues after getting endocytosed when they bind to certain receptors
By enzymes free in plasma
By being excreted as bile
By being excreted as urine via the kidneys
Binding to tissues
Factors resulting in downregulation of receptors
- Inactivation
- Inactivation of other molecules involved in second messenger system
- Temporary sequestering into the cell cytoplasms
- Destruction after getting sequestered
- Decrease in their transcription
Outline the types of receptors through which hormones exert their actions as well as their mechanisms
Ion-linked cause changes by causing changes in relative ion concentrations in cells. When hormone or other ligand binds, it changes shape of ion-linked channel to allow or prevent ions from entering. few hormones use this
G-protein linked receptors indirectly cause changes in ion-linked or enzyme-linked receptors. The alpha subunit is the one that causes the effects.
Enzyme-linked are bound to enzymes or are the enzyme themselves.
Why can one hormone have different effects on different cells?
Due to different machinery of the cells
Which lipid forms the lipid part of DAG?
Arachidonic acid
Mechanism of IP3 and DAG
IP3 diffuses into cytosol, binds to ER calcium ligand gated channels to cause release of calcium into cytosol–> formation of CAM as calcium binds to calmodulin –> CAM activates other protein kinases
DAG remains in cell membrane and activates protein kinase C which activates other proteins
How many calcium ions must bind to calmodulin for it to exert its effects?
4
State normal calcium concentration in most cells of body
10^-8 to 10^-7 mol/L
By which mechanism does atrial natriuretic peptide work?
Uses the second messenger system via cGMP to activate protein kinase G
