Nervous and Endocrine System - Hormones Flashcards
What are hormones?
-Chemicals produced by one cell that affect cell/tissue/organs elsewhere in the body.
-Regulators speed up or slow down other processes. (Homeostasis)
-Target hormones: specific tissues (FSH)
-Non target hormones: affect many tissues (epinephrine)
What are endocrine and exocrine hormones?
-Endocrine hormones: released into the blood stream.
-Exocrine hormones: released into ducts other than the circulatory system.
Describe a steroid
-1 of the 2 types of hormones.
-Fat soluble hormone.
-Diffuses into the cytoplasm (crosses the cell membrane on its own).
-Combines with receptors and diffuses into nucleus to directly turn on a gene which then begins to manufacture a particular protein.
Describe a protein
-1 of the 2 types of hormones.
-Water soluble hormone (can’t cross cell membrane).
-Binds to receptors on cell membrane which stimulates a chain reaction.
-Eventually enzymes in the cytoplasm to begin producing the needed product.
Describe negative feedback
-The nervous system and endocrine system work together in maintaining homeostasis.
-Nervous system typically acts quickly while the endocrine system responds more slowly and is longer lasting.
-Many hormones are regulated by negative feedback.
-Counteracts the initial change, maintaining homeostasis or stability.
What does the hypothalamus do?
-Regulates the release of many hormones.
-Hypothalamic releasing/inhibiting factors, produced by neurosecretory cells.
-Secreted into a portal system and stimulate or inhibit the release of hormones from the anterior pituitary (front).
-Neurosecretory cells produce ADH and oxytocin.
-Neuronal axons transport the hormones to the posterior pituitary for storage.
-ADH and oxytocin are released from axon endings into the bloodstream.
What are tropic hormones?
-Hormones whose targets are other endocrine glands.
-Hypothalamus controls their secretion.
What is the pituitary?
-Two lobes both connected to the hypothalamus.
What hormones does the posterior pituitary secret?
-Anti-diuretic hormone.
-Oxytocin.
What hormones does the Anterior pituitary secret?
-TSH (Thyroid stimulating hormone).
-ACTH (Adrenocorticotropic hormone).
-Gonadotropic hormones: FSH (follicle stimulating hormone) and LH (luteinizing hormone).
-Prolactin.
-hGH (human growth hormone).
What is the function of the Anti-diuretic hormone?
-Stimulates water reabsorbtion.
What is the function of oxytocin?
-Promotes uterine contractions during labour and stimulates milk production.
What is the function of TSH (thyroid stimulating hormone)?
-Stimulates thyroid to release thyroxine.
What is the function of ACTH (adrenocorticotropic hormone)?
-Stimulates adrenal cortex to produce cortisol, aldosterone, and sex hormones.
What are Gonadotropic hormones?
-FSH (follicle stimulating hormone).
-LH (luteinizing hormone).
-Targets the gonads (ovaries in females and testes in males), for overall reproduction health, and regulating reproduction processes.
What is the function of FSH (follicle stimulating hormone)?
-Sperm and egg production.
What is the function of LH (luteinizing hormone)?
-Sex hormone production (testosterone/estrogen+progesterone).
What is the function of prolactin?
-Targets mammary glands after child birth only.
-Sustains milk production.
What is the function of hGH (human growth hormone)?
-Targets soft tissue and bones.
-Increase protein synthesis, cell division and growth, and the breakdown and release of stored body fat.
-Dwarfism, giantism and acromegaly all result from to much or little hGH.
What is thyroxine?
-Produced by the thyroid gland.
-Stimulated by the release of TSH from anterior pituitary.
-Thyroxine stimulates most cells to increase the metabolism of fats, proteins, and carbohydrates for energy.
-Iodine is very important to thyroxine production and is actively transported into the thyroid 25x higher than other places.
What is hypothyroidism?
-Low quantities of thyroxine produced.
-In children: lack of growth and mental delays.
-In adults: fatigue, hair loss, weight gain - slow metabolism.
What is hyperthyroidism?
-Overproduction of thyroxine.
-Anxiety, insomnia, weight loss - excess metabolism are all symptoms.
What is goiter?
-Enlargement of the thyroid gland caused by insufficient iodine.
-Thyroxine can’t be made; continued secretion of TSH.
What is calcitonin?
-Produced in the thyroid gland.
-Regulates high Ca2+ levels in the blood by targeting bones, intestine and kidneys to take up calcium.
-Necessary for skeletal development, blood clotting, nerve conduction, and muscle contraction.
What is PTH (parathyroid hormone)?
-Released by the parathyroid glands in response to low blood Ca2+.
-Stimulates bone breakdown and reabsorbtion of Ca2+ into the blood.
-Kidneys are stimulated to reabsorb calcium from urine and activate vitamin D.
-Atagonisgic (opposite) to calcitonin.
What is the adrenal medulla?
-Inner layer of the adrenal gland.
-Responsible for short-term stress response.
-Neurons stimulate (sympathetic) the adrenal medulla to produce epinephrine (adrenaline) and norepinephrine (noradrenaline).
-Similar to response of sympathetic nervous system (fight or flight).
-Influences lasts 10x longer than nervous response.
-Conversion of glycogen (storage) to glucose to increase blood glucose levels. (blood sugar)
-Increases HR, breathing rate, cell metabolism, dilate blood vessels and pupils.
What is the adrenal cortex?
-Outer layer of the adrenal gland.
-Long term-stress response.
-Stimulated by ACTH to produce glucocorticoids, mineralocorticoids and sex hormones.
What are glucocorticoids (cortisol)?
-Produced by adrenal cortex.
-Promotes breakdown of proteins to amino acids and fatty acid breakdown.
-Main function is to raise blood glucose levels.
-Negative feedback: response to hypothalamus and anterior pituitary to stop release of cortisol.
-Natural anti-inflammatory.
How can cortisol help with pain/injuries but be harmful to people with stressful jobs?
-Can help power through injury by reducing pain and swelling. (Pain telling you to slow down is less important than the imminent danger).
-Can be harmful to people with stressful jobs -> body constantly pumps out cortisol because of stress -> results in constant high blood sugar levels -> can lead to diabetes, strokes or heart attacks.
What is the function of mineralocorticoids (aldosterone)?
-Stimulates Na+ re-absorption and K+ secretion levels in the blood (kidneys).
-Aldosterone release increases blood pressure.
-Water gets reabsorbed because of osmosis.
Describe the pancreas
-Both an exocrine and endocrine gland.
-Produces insulin and glucagon.
Describe insulin
-Produced by beta islet cells and released in response to high blood glucose levels (release is inhibited by negative feedback).
-Stimulates body cells (liver, muscles, and organs) to become permeable to glucose.
-Liver converts absorbed glucose to glycogen bringing blood glucose levels back to normal.
-Once glycogen stores are filled, fat and proteins are used next.
Describe glucagon
-Complementary to insulin (opposites).
-Produced by alpha islet cells and released in response to low blood glucose.
-Promotes liver to convert 1. Glycogen, 2. Fat, and 3. Protein (in that order) to glucose to bring blood glucose back to normal.
What is diabetes mellatus?
-Results when the body does not produce enough insulin or does not respond properly to insulin.
-Leads to hyperglycaemia: high blood glucose levels.
-Results in fatigue (cells can’t take in glucose), thirst, excess urine/production, poor circulation.
-To tell difference between type 1 and 2 you could taste test urine.
What is type 1 hyperglycemia?
-Type 1 (Insulin-dependent): immune system produces antibodies against beta cells.
-Treat w/ insulin.
What is type 2 hyperglycemia?
-Type 2 (insulin-independent) (adult onset): insulin receptors stop responding to insulin.
-Treat with high glucose diet and/or exercise. Genetics play a big factor.
Describe testes
-Secrete testosterone (LH) (sex organs, skin, muscles, and bone) when stimulated by LH/FSH.
-Stimulate spermatogenesis (FSH) and secondary sex characteristics (muscle mass, deeper voice, body hair, etc).
Describe ovaries
-Secrete estrogen and progesterone when stimulated by LH/FSH.
-Stimulate growth of endometrium and secondary sex characteristics (estrogen) (wider hips).
What is diabetes inspidus?
-Lack of ADH.
-Lots of dilute urine (no glucose in urine).
