Physiology 2130 Final: Prof Nissen- Endocrine system
Course CodePHYSIO 2130
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Prof Nissen- Endocrine System!
Communication systems !
-FOR CELLS IN EITHER THE NERVOUS OR THE ENDOCRINE SYSTEM TO RESPOND
THERE MUST BE A RECEPTOR."
-hormone action can be sustained more because it is circulating in the blood "
Target cell- cell that has the receptor for a certain hormone (not every cell has a receptor for
EVERY hormone, thus a cell may be a target cell for one type of hormone, but not for another
type). To be activated by the hormone, the cell must have the receptor for that hormone. "
In the pituitary:"
In the thyroid:"
In the pancreas:"
In the Adrenals:"
** hormones can be released by GLANDS (pituitary, thyroid, hypothalamus) OR NORMAL
CELLS (heart, intestinal cells)"
Hormone- chemical signal secreted into the bloodstream that goes to act on distant tissue."
Ex. pancreas releases insulin which acts on the entire body"
Protein/ Peptide hormones!
-a.a. are their precursor (building blocks), hormones are categorized by their precursor! "
-hydrophilic (think of a protein shake), very soluble in water"
-blood is mainly water thus protein dissolves well in blood and doesn't need to bind on
to anything to travel through the blood "
-the receptors for proten/peptide hormones are in the plasma membrane "
Ex. hypothalamic and pituitary hormones—> insulin "
Type of chemical signal
Where does the chemical
signal travel through?
synapse (place btwn two
speed of communication
chemical signalling leads to…
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Steroid Hormones !
-do not dissolve in blood and must be transported by binding to blood
-receptors found intracellularly (bc steroid hormones are hydrophobic and do
not want to be exposed to blood outside the cell)"
Ex. testosterone, estrogen, cortisol"
Amine Hormones !
-precursor: tyrosine (a.a.)"
Depending on which R group is attached to the tyrosine, the amine hormone can
-hydrophilic (dissolve in blood, no binding necessary for transport through blood,
receptor on plasma membrane). Ex. hydrophilic: catecholamines (epinephrine)"
-OR hydrophobic (not soluble in blood, must bind to blood protein for transport
through blood, receptor inside cell). Ex. lipophilic: thyroid hormones (T3 , T4)"
Anterior pituitary- has endocrine cells "
Posterior pituitary- has nervous system cells—> neurohormones bc they are released by
—> oxytocin: peptide hormone that promotes uterus contractions and promotes milk excretion"
—> ADH (vasopressin): peptide hormone that promotes water reabsorption in the kidneys"
-both are peptide hormones meaning are hydrophilic, dont need to bind to anything for
transport through blood, and their receptors are found on the plasma membrane. "
-diabetes insipidus (nothing to do with insulin type diabetes): lack ADH or mutated ADH
receptors—> need to pee a lot "
Hormone binding to receptors!
1. Hydrophilic hormones bind to membrane receptors on the outside of the cell and this
generates intracellular events—> this tends lead to ALTERING OF EXISTING PROTEINS
-opening ion channels, changing enzyme activity"
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