3.3 the endocrine system Flashcards
The endocrine system releases hormones that are peptides, proteins, or steroids. Hormones travel to target sites via the blood. Hormones can alter the metabolism of target cells, tissues, or organs. Compare the action of insulin and glucagon in blood sugar regulation. Describe how diabetes can result from a hormonal imbalance. Describe the action of thyroid stimulating hormone and thyroxine in metabolism. Describe the role of antidiuretic hormone (ADH) in osmoregulation. Discuss links bet (39 cards)
Whats the endocrine system?
The endocrine system consists of the tissues (mainly glands) that create and release hormones.
What are hormones?
Hormones are chemical messenegrs which coordinate(travelling through bloodstream) different functions in the body; controlling activites in areas such as growth, reproduction, blood solute concentration, blood temperature etc.
What are the three types of hormones
- Peptide hormones (consists of short polypeptide chain of amino acids)
- Protein hormones (longer chains of amino acids)
- Steroid hormones (lipid-based hormones)
Describe the properties of the peptide hormones.
- Synthesis: require cleavage to activate
- Storage: stored in vesicles
- Solubility: most are polar and travel through the blood
- Receptors: bind to receptors in the cell membrane
examples: insulin, glucagon, anti-diuretic hormone(ADH)
Describe the properties of protein hormone.
- Synthesis: synthesised from tyrosine
- Storage: stored before release
- Solubility: some are polar (water soluable)
- Receptors: some act on cell membrane receptors others act on nuclear membrane
examples: adrenaline, thyroxine
Describe the properties of steroid hormones
- Synthesis: synthesised from cholestrol
- Storage: immediently released into bloodstream
- Solubility: non-polar (lipid soluable)
- Receptors: bind to intracellular receptors
examples progesteone, oestrogen, testrone
What hormones can travel in the cell?
The protein and peptide hormones are often polar and cannot travel into the cell. As they cannot enter they bind to target cell membranes which have complementary receptors to the hormones.
sterioid hormones.are lipid soluable and bring about their effect by travelling into the cell (diffsue through phospholipid bilayer)and binding to internal receptors.
What are the major endocrine glands of the human body and their location?
- Hypothamus (brain)
- Pituitary glands (brain)
- Thyroid gland (front of the throat)
- Parathyroid glands (four tiny glands located around the thyroid in the throat)
- Thymus gland (upper chest, behind your breastbone[sternum]).
- Adrenal glands (two small triangle-shaped glands in the upper abdomen)
- Pancreas (high in the abdomen)
- Ovary (female gonad, located lower left and right quadrants of the abdomen)
- Testes (male gonad, located inside the scrotum).
What hormones does the pituaitary gland release
- Oxytocin (uterine contractions during childbirth)
- Antidiuretic ADH (reabsorption of water in the kidneys)
- Human growth hGH (grwoth of body cells and tissues)
- Follicle stimulating FSH ( stimulates ovaries and testes
- Luteinising LH( stimulates ovulation [release of eggs] in females and the release of testosteron in males)
- Thyroid-stimulating TSH (stimulates the activity of the thyroid gland
What hormones does the thyroid gland release and describe its action.
Thyroxine, which stimulates metabolism and heat production.
What hormones does the parathyroid gland release and describe its action.
Parathyroid (PTH), which stimulates the release of calcium from bone into the blood.
What hormones does the pancreas release and describe its action.
Insulin and glucagon, loweing blood glucose as well as raising blood glucose.
What hormones does the adrenal glands release and describe its action.
Adrenaline, which increases blood sugar, constricts blood vessels and increases heart and breathing rate.
What hormones does the ovaries release, and describe its function.
Oestrogen and progestrone, developing female secondary sexual characteristics and maintaing uterine lining.
What hormones does the testes release and describe its function.
Testostrone, developing male secondary sexual characteristics, muscle development and controls the sperm production.
Why is the pituitary gland called the master endocrine gland?
The pituitary gland is located at the base of the brain and acts like the master controller, releasing hormones which control other endocrine glands e.g. TSH which then stimulates the thyroid gland.
What is glucose?
Glucose is an essential for energy supply, and is broken down through both aerobic and anaerobic respiration releasing ATP.
Why most glucose be kept between tolerance limits, how can it exceed them?
Glucose must be kept within certain tolerance limits to avoid certain disease.
Homeostatic processes such as negative feedback operate to keep glucose levels between tolerance levels, using both insulin and glucagon (both peptide hormones).
Eating foods(specifcially carbohydrates), drinking sugary drink, fasting and exercise can lead to high blood glucose levels.
Why does glucose need insulin?
Insulin’s main job is to move glucose from our bloodstream into the body’s cells to make energy. If you don’t have enough insulin, glucose builds up in your bloodstream rather than getting into your cells to provide energy.
Use the stimulus response model to describe the blood glucose regulation.
Cells in the islets of langerhans, in the pancreas have chemoreceptors which are sensitive to glucose concentration in the blood (note there is two cells: alpha and beta cells).
When blood glucose levels are too low, the alpha cells in the pancreas secrete more glucagon (hormone which travels in the blood and can travel to complementary receptors on livers cells. Causing the conversion of Glycogen to glucose.
glycogen stores excess glucose, which can be broken down later, and released into the bloodstream, where the blood glucose levels rise back to normal
When blood glucose levels are too high, beta cells will release more insulin, more insulin binding to muslces and liver cells causes them to absorp and store more glycogen (storage form of glucose), reuslting in a normal blood glucose level.
What does insufficient production of insulin lead to?
An insufficent prodution of insulin leads to an accumulation of glucose in the blood and may result in diabetes.
What is metabolism?
Metabolism refers to the vast array of biochemical reaction occuring in an organism. Amongst which cell repisration such as which release energy for ATP production and heat are most important.
What hormone controls metabolism?
Thyroxine is a hormone produced by the thryoid gland and is secreted into the circulatory system (bloodstream). Acting in most cells to regulate metbaolism, increasng the basal metabolic rate (BMR). As a result thyroxine promotes the generation of heat.
Is iodine required for the production of thyroxine.
Iodine is required for the production of thyroxine, a lack of iodine can cause the thyroid to enlarge, causing a condition known as goitre (enlarged thryoid gland).
