Yr 12 endocrine Flashcards
Give the order of organization of cells to systems
cells - tissues - organs - systems
What 2 systems help the body work in a co-ordinated way.
endocrine
nervous system
Homeostasis
maintaining a stable internal environment
e.g. pH, temp, sugar level.
Endocrine gland
A gland that secretes hormones directly into nearby tissue
Also called Ductless gland
Exocrine gland
A gland that secretes into a duct that carries the secretion to the surface of the body cavities
Give 4 examples of exocrine glands
sweat glands
mucous glands
salivary glands
alimentary canal glands
Hormones
Chemicals secreted by the endocrine glands and are transported throughout the body in the blood
Enzymes
Proteins that speed up chemical reactions (specific) in the body.
Type of organic catalyst
Hormones can change…
The functioning of cells
How do hormones change the functioning of cells?
they change the type, activities or quantities of proteins
What effect do hormones have on enzymes?
change their activity
change their concentration
What are 3 ways that hormones affect cells?
- activate genes in the nucleus to make certain proteins
- change the shape or structure of an enzyme that turns it on or off.
- change the rate of production of an enzyme or protein.
Can a hormone affect any cell?
No they can only affect cells with the right receptors
e.g. all cells, target cells, target organs
What chemicals could be hormones?
steroids, proteins, amines
Steroid hormones
Give 4 examples
are lipid soluble
oestrogen, progesterone, cortisol and aldosterone
Aldosterone
hormone that regulates blood pressure
How are steroids transported?
They bind to transport proteins and are carried in the blood.
What happens when steroid hormones reach the target cells?
They separate from the transport protein and diffuse across the cell membrane.
Once inside they combine with a receptor protein
(cytoplasm or nucleus ).
Hormone-receptor complex
Hormone connects to receptor protein.
Activates genes that control the formation of specific proteins.
How does the hormone-receptor complex activate protein formation?
It binds to a promoter section of a certain gene, starting (or inhibiting) transcription, and therefore protein synthesis.
Do steroid hormones act quickly?
No, but the effect is long lasting.
transcription
DNA is copied to RNA.
translation
RNA is used to make proteins
What type of hormones are water soluble?
Protein and amine
Why can’t protein/amine hormones unable to diffuse a cell membrane?
They are not lipid soluble.
How do protein/amine hormones activate a target cell?
They attach to a receptor protein in the membrane of the target cell.
This hormone-receptor complex triggers a secondary messenger chemical to diffuse through the cell and activate a particular enzyme.
What type of hormone is insulin?
protein
It binds to the receptor protein of a cell and increases the amount of glucose the cell absorbs.
Do proteins/amines act quickly?
Yes, but the effect is short lasting.
“receptor proteins are specific”
What does this mean?
each type of receptor will bind with only one type of molecule,
What analogy can be used for receptor proteins?
lock and key
What is meant by the term “saturation” in regard to receptor proteins?
no more receptor proteins are free to bind .
if a cell is saturated with insulin molecules, what would happen if more glucose is taken into the body?
The cell cannot take on any more hormone, so the glucose will increase in concentration in the blood.
Do all cells have the same type and number of protein receptors?
no - each type of cell is different, so has different sensitivity to a hormone.
Does one hormone make one enzyme molecule?
No, one hormone molecule may make thousands of enzyme molecules.
The process is called enzyme amplification
What type of reaction is an enzyme amplification?
cascade reaction
How are hormones turned off?
The hormone molecules are broken down.
Where are hormones broken down?
How are they excreted?
liver and kidneys
Degrade hormones are excreted in bile or urine
Why must the amount of hormone released be strictly controlled?
to maintain homeostasis
What type of feedback controls hormone production?
negative feedback
What is negative feedback?
the response produced by the secretion of the hormone is opposite of the stimulus that caused the secretion.
