Hormones and the endocrine system Flashcards
What are hormones?
chemicals released by cells that affect cells in other parts of the body.
Source: Endocrine glands secrete hormones directly into the blood.
Transport: Hormones are carried to every cell by the blood.
Target cells: Cells with receptors for the hormones are target cells. A hormone may have one specific target cell or a hormone may target every cell of the body.
What is the purpose of the hypothalamus and the pituitary gland?
The hypothalamus stimulates the release of hormones by the pituitary gland.
The pituitary gland is “the master gland” because it produces so many different hormones.
What are and describe the two different types of hormones
Steriod and protein hormones
what is a steroid hormone?
made from cholesterol (a lipid)
fat-soluble (so can diffuse into cells)
include male and female sex hormones and cortisol
What is the Steroid hormone function?
- hormone diffuses into target cell
- hormone binds to hormone receptor
- hormone receptor complex diffuses into nucleus
- hormone receptor complex initiates a gene
- DNA is transcribed (genetic code copied into mRNA)
- mRNA carries message to ribosomes and a new protein is created
What is a protein hormone?
water-soluble (so can’t diffuse into cells); must bind to receptors on the cell membrane
include insulin and growth hormone
what is the protein hormone function?
- hormone binds to receptor on cell membrane
2/3. hormone receptor complex activates an enzyme that changes ATP → cAMP - cAMP acts as a secondary messenger that activates other enzymes or proteins
note: nucleus is not involved
What is insulin and glucagon?
Insulin and glucagon are both protein hormones (chains of amino acids).
where is insulin and glucagon synthesized?
pancreas (insulin is beta, glucagon is alpha)
What is the responsibility of insulin?
A) Decreases blood glucose levels.
B) Stimulates body cells to become permeable to glucose (required to open the protein channels so that glucose can diffuse with the concentration gradient.)
C) Stimulates the liver to store glucose as glycogen
what is glucagon’s relationship to insulin?
-As blood glucose levels fall, insulin secretion ceases.
-The hormone glucagon counteracts insulin.
-When blood sugar levels fall (e.g. if you skip a meal), glucagon is released.
-Both insulin and glucagon maintain blood sugar homeostasis.
What is the feedback loop for insulin?
- blood glucose is high
- sensor and control centre: beta cells in pancreas release insulin
- effectors: Liver converts glucose to glycogen, Body cell uptakes more glucose
- Result: Blood sugar levels drops
What is the feedback loop for glucagon?
- blood glucose is low
- sensor and control centre: alpha cells in pancreas release glucagon
- effector: Liver converts glycogen to glucose
- results: blood sugar rises
What is diabetes?
occurs when pancreas can’t release enough insulin when blood sugar is low.
-Without insulin, a person’s blood sugar rises after a meal, but they have a lack of energy.
-Large amounts of urine are produced to rid the body of sugar. -Symptoms include thirst, and frequent urination.
-Insulin must be administered by injection or a pump.
What are the difference groups of hormones?
- Sex hormones;
- Blood hormones;
- Metabolic hormones;
- Stress hormones;
- Water balance hormones.
What are the difference groups of hormones?
- Sex hormones;
- Blood hormones;
- Metabolic hormones;
- Stress hormones;
- Water balance hormones.
Testosterone and estrogen
-stimulates the development of sperm and causes secondary sexual characteristics in males; produced in the testes
-develops endometrium in uterus, causes secondary sexual characteristics in females; produced by the ovarian follicle
progesterone
completes the development of the endometrium, inhibits ovulation; produced by the corpus luteum
What is the corpus luteum?
When an egg is released from a follicle it is called ovulation.
After ovulation, the tissue left over is called the corpus luteum. This is where progesterone is produced.
FSH and LH
-stimulates the maturation of the follicle in the ovary and stimulates the production of sperm; produced by the pituitary gland
-causes ovulation and formation of corpus luteum in ovary, stimulates the production of testosterone in males; produced by the pituitary gland
What is the feedback system of the male reproductive system?
- Testosterone levels are low
- sensor and control centre: hypothalamus releases GnRH, which then causes the pituitary gland to release LH and FSH
- Stimulates the testicles, which then produces testosterone, which prevents the release of LH and FSH
What is the feedback of the female reproductive system?
- estrogen and progesterone levels are low
- sensor and control centre: hypothalamus releases GnRH, which causes the pituitary gland to release LH and FSH
- stimulates the ovaries/follicles, causing it to release estrogen and progesterone to travel to the uterus during ovulation; this then causes LH and FSH production to cease
prolactin and oxytocin
-stimulates milk production in mammary glands; produced by the pituitary
-causes uterine contractions during labour; produced by the hypothalamus (released by pituitary)
Erythropoetin and Thymosin
-stimulates red blood cell production and initiates hemoglobin production; produced by the kidneys
-promotes production and maturation of white blood cells; produced by the thymus
T3 and T4
- determine the rate of oxidation of glucose
- determine the metabolic rate
- produced by the thyroid
T3 and T4
- determine the rate of oxidation of glucose
- determine the metabolic rate
- produced by the thyroid
What is the feedback loop of T3 and T4
- influx of T3, T4, calcitonin
- hypothalamus stops releasing TRH, which also stops pituitary from releasing TSH
- causing the thyroid gland to slow production of T3, T4 and calcitonin
- lower levels of T3 and T4 then cause the increase of TSH and TRH production
Parathyroid hormone and calcitonin
-increases blood calcium level by stimulating the loss of calcium from bone; produced by the parathyroid glands
-decreases blood calcium levels; produced by thyroid gland
Growth hormone
stimulates bone and muscle growth and fat metabolism; produced by the pituitary
Epinephrine and cortisol
-initiates stress responses; produced by adrenal glands
stress responses include increased heart rate, blood pressure, and metabolic rate; dilated blood vessels to muscles, bronchioles, and pupils
this responses is often called the “fight or flight” response
-stimulates carbohydrate metabolism, raises blood glucose level; produced by adrenal glands
Antidiuretics hormone
stimulates water reabsorption in the kidneys, prevents dehydration; produced by hypothalamus (released by pituitary)
Angiotensin and aldosterone
-stimulates the release of aldosterone and causes the constriction of blood vessels; produced in nephrons
-increases amount of Na+ reabsorbed by the kidneys, increases blood pressure; produced by adrenal glands
What is the feedback loop of angiotensin and aldosterone
- Blood pressure falls
- renin to produce angiotensogen/angiotensin
- angiotensin stimulates aldosterone, which causes salt retention in blood
- More water will overall then be in the blood, and urine will be more concentrated
- causes blood pressure to rise again due to more water being retained
