Endocrine System Flashcards
Steroid Hormones
lipid- solube.
bind to transport proteins in bloodstream, then diffuse across cell membrane and combine with receptor protein in nucleus or cytoplasm. the hormone-receptor complex activates genes controlling the synthesis of particular proteins, by binding to promoter section of the gene and either stimulating or inhibiting protein synthesis. slow to take effect, but long lasting.
Protein & Amine Hormones
water-soluble.
bind to receptors on cell membranes, which causes a secondary messenger to diffuse through cell and activate particular enzymes. fast to take effect, but short lasting.
Hypothalamus
- secretes releasing and inhibiting factors, which stimulate and slow down the secretion of a hormone. (both of these factors through blood vessels to the anterior lobe of pituitary gland)
- other hormones are produced by the hypothalamus and then taken to the posterior lobe of the pituitary gland via nerve fibres
Anterior lobe
controlled by releasing and inhibiting factors. produces and releases: Follicle-stimulating hormone Luteinising hormone Growth hormone Thyroid-stimulating hormone Adrenocorticotropic hormone Prolactin
Posterior lobe
releases:
Oxytocin
Anti-diuretic hormone
FSH
stimulates the development of the follicles in the ovaries, and the production and maturation of sperm in the testes
LH
stimulates ovulation and forms corpus luteum in the ovaries, and the production and secretion of testosterone in the testes
Growth hormone
stimulates body growth by increasing the rate of protein synthesis; secreted throughout life
TSH
stimulates production and secretion of the hormones from the thyroid gland
ACTH
stimulates the production and secretion of the hormones from the adrenal cortex
Prolactin
initiates and maintains milk production in females
Oxytocin
stimulates the contraction of uterine muscles, especially during labour, and also stimulates contraction of cells in the mammary glands, therefore the release of milk during breastfeeding
ADH
stimulates the kidneys to remove water from the urine being formed by increasing permeability of DCT and CDs. i.e. increased water reabsorption, and can also cause, in high concentrations, vasoconstriction of arterioles. (hence why it can be called vasopressin)
Pineal gland
releases melatonin, which is involved in the regulation of sleep patterns
Thyroid gland
releases thyroxine, which controls body metabolism, and is often involved in increasing the body’s internal temperature
Parathyroid glands
release parathyroid hormone, which increases calcium levels in the blood and phosphate excretion in the urine
Thymus
releases group of hormones called thymosins, which influence the maturation of T-lymphocytes
Adrenal Medulla
releases adrenaline, which helps to prepare the body for a situation involving rigorous exercise and noradrenaline, which has similar effects to adrenaline, in particular increasing the rate and force of the heartbeat
Adrenal Cortex
releases cortisol, which promotes normal metabolism, helping the body to withstand stress and repair damaged tissues, and aldosterone, which increases the amount of potassium and decreases the amount of sodium in the urine.
Pancreas
releases:
insulin, which reduces the amount of glucose in the blood by promoting the uptake of glucose from the blood by cells; in the liver, it causes the conversion of glucose to glycogen and fat, in the skeletal muscles, it causes the formation of glycogen from glucose, and in adipose tissue, causes glucose to be converted into fat
glucagon, which does the opposite to insulin, mainly by promoting the breakdown of glycogen to glucose in the liver, and the breakdown of fat in the liver and adipose tissues
