Endocrine Study Guide Flashcards
What are the two types of organization of endocrine cells?
The secretory cells can be organized as:
- a single organ with only an endocrine function
- cells housed in small clusters within organs or tissues that have some other primary function
What are the three types of reflex?
- Hormonal Stimulation
- Humoral Stimulation
- Nervous Stimulation
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
- If the rate of synthesis and release increases, then the concentration of the hormone within the blood is greater
- If the rate of synthesis and release decreases, then the concentration of the hormone within the blood is less
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
- Do not dissolve readily in blood
- Carriers are water-soluble proteins made by the liver
- Carrier proteins protect the hormone from early destruction
- binding between hormone and carrier is temporary. Most of the hormone is bound while only unbound hormone is able to exit the blood and bind to target cell receptors
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
- the unbound lipid-soluble hormone diffuses into the cell and binds an intracellular receptor (in the cytosol or nucleus) forming the hormone-receptor complex
- Hormone-receptor complex then binds to a specific DNA sequence in regions of chromatin called hormone-response elements.
- This binding stimulates mRNA synthesis
- The mRNA is then translated and a new protein is synthesized
Target cell response to Water-soluble hormone
- Hormone (first messenger) binds to the receptor on plasma membrane and induces a change in the shape which activates the receptor
- This results in the formation of a second messenger that modifies cellular activity on the inside of the cell
- multiple results possibly with different signal transduction pathways
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