02- Cell Signaling Flashcards
1
Q
What are the general characteristics of hormones?
A
- they are molecules synthesized by specific tissue called glands
- they are secreted directly into the bloodstream which carries them to their sites of action.
- they are present at very low levels in the circulatory system
- they specifically affect or alter the activities of the responsive tissue
- they act specifically via receptors located on, or in target tissue
2
Q
What are the four primary arenas of hormone action?
A
- reproduction
- growth and development
- maintenance of internal environment
- energy production, utilization and storage
3
Q
What is endocrine?
A
The internal secretion of biologically active substances
4
Q
What is exocrine?
A
The external secretion of biologically active substances e.g. through sweat glands, mammary glands or ducts
5
Q
What is a hormone?
A
A hormone is a substance released by an endocrine gland and transported through the bloodstream to another tissue where it acts to regulate the functions
6
Q
What are some examples of hormones used in digestion?
A
- gastrin: secreted by G cells in stomach and stimulates the parietal cells to secrete gastric acid (HCl). It also promotes gastric and intestinal mobility.
- secretin: secreted by endocrine cells in small intestine and stimulus the pancreatic cells to secrete bicarbonate. It also inhibits gastrin and gastric acid secretion.
- CCK (cholecystokinin): secreted by endocrine cells of small intestine; neurons of brain and gut and stimulates the release of pancreatic enzymes, contraction of the gall bladder and secretion of bile from pancreas and gallbladder
7
Q
What are some examples of hormones used in homeostasis?
A
- parathyroid hormone (PTH): secreted by the parathyroid glands to increase blood calcium levels and decrease phosphate levels in the body. It absorbs calcium in small intestines, resorption of calcium in bones to release Ca++ into the blood and reabsorbed calcium in the kidneys.
- calcitonin: secreted by parafollicular cells of the thyroid gland to decrease blood calcium levels by decreasing bone resorption and calcium reabsorption in the kidney .
- ANF: secreted by the atria of the heart in response to atrial stretch. It increases sodium excretion
- calcitriol: the more active form of vitamin D. It absorbs calcium and acts in the kidneys and lungs
- aldosterone: secreted by the adrenal glands to absorb sodium and release potassium
8
Q
What are some examples of hormones used in metabolism?
A
- insulin: secreted by pancreatic cells to absorb glucose from the bloodstream and synthesizes proteins and lipids
- glucagon: secreted by the pancreatic to secrete more glucose into the bloodstream
- cortisol: secreted by the adrenal glands. It regulates the body’s stress response.
- thyroxin: secreted by thyroid gland and geckos in metabolism. It maintains fetal development
- epinephrine: secreted by the medulla of the adrenal glands and increases cardiac output and raises glucose levels in the blood. It triggers the fight or flight response
9
Q
What are some lipophilic (attracted to lipids) hormones and their functions?
A
- progesterone: produced by corpus luteum. It maintains pregnancy and develops the mammary glands.
- estradiol: stimulates proliferation of endometrium, maintains bone development and develops the secondary female sex characteristics
- testosterone: helps in sexual differentiation from female phenotype, formation of sperm and development of secondary male sex characteristics
- cortisol: secreted by the cortex of the adrenal glands. It increases proteolysis, decreases protein synthesis, increases gluconeogenese and decreases activity of the immune system
- aldosterone: secreted by the cortex of the adrenal glands, it increases sodium ion retention, increases potassium ion retention and increases blood pressure
- calcitrol
- thyroxine: increases basal metabolic rate, increases heat generation and O2 consumption
