What are the two types of organization of endocrine cells?
The secretory cells can be organized as:
What are the three types of reflex?
Hormonal Stimulation
-the release of hormones from the endocrine gland is triggered by the binding of another hormone
What is an example of Hormonal Stimulation
When the Anterior Pituitary releases TSH which binds to the thyroid gland causing the release of TH
Humoral Stimulation
when a endocrine gland is stimulated to release their hormones in response to a changing level of nutrient molecules or ions within the blood
What is an example of Humoral Stimulation
When blood glucose levels are high/increases which stimulates the pancreas to produce insulin
Nervous Stimulation
is when there is direct stimulation from the nervous system, which causes the release of hormones from the gland cells
What is an example of Nervous Stimulation
The sympathetic division is activated and sympathetic preganglionic axons stimulate adrenal medulla to release epinephrine and norepinephrine
Hormone Half Life
-the necessary time to reduce hormone’s concentration half of its original level
What are the two primary factors that determine circulating hormone levels?
Hormone synthesis in endocrine gland:
Hormone Elimination:
Hormone synthesis in endocrine gland
Hormone elimination
1) Enzymatic Degradation- normally occurs in liver cells
2) Removal of the hormone from the blood either by its excretion from the kidneys or by its uptake into target cell.
- The faster the rate hormone elimination-> the lower the hormone concentration within the blood
- the Slower the rate of hormone elimination-> the higher the hormone concentration within the blood
Half life of water soluble hormones vs lipid soluble hormones
Water soluble hormones- have a short half life
Lipid soluble hormones-have a long half life
Why do lipid soluble hormones have a longer half life than water soluble hormones?
Because their carrier proteins provide protection to them
Transport of lipid soluble hormones
USE CARRIER MOLECULES
Transport of Water soluble hormones
travel freely through blood
-only a few use carrier proteins to prolong their life.
Target cell response to lipid-soluble hormone
Target cell response to Water-soluble hormone
Upregulation
Increases the number of receptors
Increases sensitivity to hormones
-sometimes occurs when blood levels of hormone are low
-sometimes occurs with changes in development, cell cycle, and cell activity
Down regulation
Decreases the number of receptors
Decreases sensitivity to hormones
-Sometimes occurs when blood levels of hormone are high
-Sometimes occurs with changes in development, cell cycle, and cell activity
What are the three types of Hormone interactions?
Synergistic
Permissive
Antagonistic
Synergistic
Hormones work together to produce a greater effect
Example of a Synergistic interaction
Estrogen and Progesterone
Permissive
first hormone allows action of second hormone