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.