Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
26 Cards in this Set
- Front
- Back
|
Endocrine system
|
With the nervous system, regulates virtually all body functions
Effects are slower, but longer-lasting than nervous system effects |
|
|
Major endocrine glands
|
Have hormone production as their primary function
Many other organs produce hormones (e.g., stomach, duodenum, heart, kidneys). |
|
|
Hormones:
Steroid hormones |
Are derived from cholesterol.
They are only produced by the gonads (testes and ovaries) and the adrenal cortex |
|
|
Hormones:
Amino acid-based hormones |
Vary in size from derivatives of single amino acids to large proteins.
They are produced by all other endocrine glands. |
|
|
Hormone effects
|
Affect target cells by:
Change in membranes via affecting membrane potential or opening or closing channel proteins Stimulate protein synthesis Activate or deactivate enzymes Stimulate secretion Stimulate mitosis |
|
|
Amino acid-based hormones usually bind to receptors
|
On the cell membranes of target cells. (exception: thyroid hormone)
|
|
|
Steroid hormones (and TH) bind to receptors
|
Within target cells
|
|
|
Second messengers for the AA based hormones mode of action is
|
1. Hormone (the “first messenger”) binds to a receptor protein on the cell membrane
2. Reactions in the cell membrane cause the production of a chemical (the “second messenger”) which will be released to the cytoplasm 3. The second messenger will, either directly or indirectly, trigger a response in the cell |
|
|
Cyclic AMP cAMP is the best known 2nd messenger
|
5 steps:
1 - hormone-receptor bonding 2 - activation of G protein 3 - conversion of ATP to cAMP 4 - activation of protein kinase 5 - response |
|
|
Second messenger:
Phospholipase |
Membrane-bound enzyme
|
|
|
To give a response
|
IP3 causes the release of Ca++ from the ER. This activates intracellular enzymes. Diacylglycerol activates a protein kinase.
The 2 mechanisms work together to give a response. |
|
|
Steroids directly enter
|
ALL cells, without needing a surface receptor protein.
|
|
|
Steroids will only affect cells which have
|
The proper receptors in the nucleus.
|
|
|
Variable affects of hormones
|
blood levels of hormone
number of receptors/cell affinity: the strength of the hormone-receptor bond half-life: speed with which the hormone is broken down or removed from the blood (minute to hours) |
|
|
Up regulation
|
In “up regulation”, target cells produce more receptors in response to the presence of the hormone
|
|
|
Down regulation
|
In “down-regulation”, target cells lose receptors in response to persistent high hormone levels (desensitization)
|
|
|
Control of hormonal release:
Humoral |
Gland directly reacts to levels of substances in blood
|
|
|
Control of hormonal release:
Neural |
Gland signaled by nerve cells
|
|
|
Control of hormonal release:
Hormonal |
Gland stimulated by presence of other hormones
|
|
|
The master gland
|
The pituitary (=hypophysis) produces:
1 - hormones which have direct effects 2 - tropic hormones, which regulate other endocrine glands The release of many pituitary hormones is hormonally regulated by the hypothalamus of the brain through releasing hormones. |
|
|
Posterior lobe
|
(Neurohypophysis)
Stores 2 hypothalamic hormones. |
|
|
Anterior lobe
|
(Adenohypophysis)
Makes hormones. |
|
|
Hypophyseal portal system
|
Carries blood from hypothalamic capillaries to hypophyseal capillaries.
|
|
|
Two hormones produced by the hypothalamus are
|
Delivered to and released by the posterior lobe of the pituitary
ADH + Oxycotin |
|
|
ADH
|
(Antidiuretic hormone) is formed in the supraoptic nucleus.
|
|
|
Oxytocin is formed in the
|
Paraventricular nucleus
|
