Hormones Flashcards
Pituitary gland
Sits underneath the hypothalamus (Hypothalamus meaning-lower than the thalamus), Has two lobes- Anterior is bigger, at the front of the brain, Posterior is smaller, at the back of the brain
Hypothalamus
Secretes releasing and inhibiting factors (hormones) into the blood that target the cells of the anterior pituitary causing it to produce and secrete/inhibit the desired hormone
What does the anterior pituitary secrete
Growth hormone, Follicle stimulating hormone, Luteinising hormone, Thyroid stimulating hormone, Adrenocorticotropic hormone, Prolactin
Growth hormone
Targets all cells of the body (need everything to grow), Stimulates body growth of the skeleton by increasing the rate at which amino acids are built into proteins, Increases muscle mass and bone density, Peaks at 20 and then declines
Follicle stimulating hormone
Targets the ovary in females and testes in males, Females- stimulates the development of follicles which contain eggs, Males- stimulates production and development of sperm, Attaches to receptors of the cell membrane
Luteinizing hormone
Targets the ovary in females and testes in males, Females- stimulates ovulation (release of egg from the ovary’s) and the development of the corpus luteum, Males- stimulates interstitial cells in the testes to secrete testosterone (dominant hormone in males)
Thyroid stimulating hormone
Targets the thyroid gland (in the neck), Stimulates the release of hormones from the thyroid such as thyroxine, Water soluble
Andrenocorticotrophin (ACTH)
Targets the adrenal cortex (in the kidneys adrenal gland), Stimulates the release of corticosteroid hormones from the adrenal cortex, Relates to biological stress (works with sympathetic nervous system)
Prolactin
Targets the mammary glands, Initiates and maintains milk secretion in females
Antidiuretic hormone/vasopressin
Targets distal convoluted tubule and collecting duct of the nephron in the kidneys to remove water from urine and return it to the blood stream, Inhibited by alcohol, Causes secondary messengers within the cell to activate cellular enzymes, If there is a lot of ADH there would be an increased concentration of urine but less quantity
Oxytocin
Targets the muscles of the uterus and the mammary glands/breasts, Causes contractions of the muscles in the uterus during childbirth, Causes contractions of the mammary cells which results in the release of milk during breast feeding
Types of hormones
Amino acid hormone/protein amine hormone- Any hormone released form the pituitary gland, “Ine”
Steroid hormone- lipid soluble, “ol” or “one”, E.g testosterone
Thyroid gland
Produces thyroxine which is made from iodine and an amino acid, Thyroxine targets most cells and regulates metabolic rate by regulating energy production from cell respiration (glucose + O2 —> Energy (ATP and heat) + CO2 + H20), Thyroxine increases body temperature as some energy produced is heat energy, Produces calcitonin which promotes storage of calcium in the bones instead of the blood and thus reduces blood calcium levels- prevents osteoporosis
Hyperthyroidism
When the thyroid produces too much thyroxine, Symptoms- Goiter- enlargement of the thyroid gland, Exophthalmos- bulging eyeballs
Hypothyroidism
Not enough thyroxine produced meaning a person becomes constantly fatigued
Parathyroid gland
Normally 4 but can have up to 8, Produces parathyroid hormone which targets the bones and kidneys, Increases blood calcium and phosphate levels, Works antagonistically with the thyroid gland through the hormone calcitonin (thyroid reduces blood calcium levels, parathyroid increases blood calcium levels)
Thymus
Increases in size until puberty where it then shrinks considerably to around 15% left by age 50, Secretes thymosins which targets T lymphocytes (white blood cell) which stimulates the development and maturation of T lymphocytes
Testes
Produces testosterone which targets many tissues, Stimulates sperm production, growth of the skeleton and muscles and male secondary sexual characteristics (balding, increased body hair), If too much testosterone in the female body they will start to develop the male secondary sexual characteristics
Ovaries
Produces oestrogen which targets many tissues, Stimulates development of the female secondary sexual characteristics and begins thickening of the endometrium, Produces progesterone which targets the uterus and mammary glands, Maintains the endometrium lining and prepares the mammary glands for milk secretion
Adrenal medulla
Inner part of adrenal gland, Secretes adrenalin and noradrenalin which targets most tissue areas, Have similar effect to the sympathetic nervous system (prepare body for ‘flight or fight’), Under the control of the nervous system
Adrenal cortex
Produces corticosteroids, Subdivided into mineralocorticoids, glucocorticoids and gonadocorticoids, Main mineralocorticoid- aldosterone which targets the kidney by increasing Na+ reabsorption and K+ excretion from the body in the kidneys, Main glucocorticoid- cortisol which targets most cells of the body by promoting normal metabolism, helping the body deal with stress and promoting the repair of damaged tissues, if too much is excreted it can make stress worse, Gonadocorticoids- produce mainly androgens (testosterone) and some oestrogens
Pancreas
Endocrine and exocrine (produces digestive enzymes), Secretes glucagon and insulin, Insulin- targets most cells of the body as well as the liver by stimulating cells to take up glucose and store it as glycogen or at thus reducing blood glucose levels, Glucagon- targets fat cells and the liver by increasing blood glucose levels by stimulating the breakdown of glycogen and fat from cells into glucose, Work antagonistically together (insulin reduces blood glucose levels, glucagon increases blood glucose levels)
Pineal gland
Secretes melatonin which regulates sleep patterns, As it gets darker the pineal gland is stimulated to produce more melatonin, Light pollution means that melatonin isn’t produced as much as needed
Exocrine organ
Secretes onto a body surface/area
Endocrine organ
Produces a hormone that goes directly into the blood stream
