Endocrine System Flashcards
endocrine system
The endocrine system responds more slowly to a stimulus by producing and secreting hormones into the bloodstream to alter the activities of an effector
hormone production and secretion
Hormones are secreted by a stimulus, and the stimuli that trigger endocrine glands
Hormonal stimulus - one hormone stimulates the secretion of another
Humoral stimulus - changes in ion or nutrient blood levels, e.g. glucose, Ca2+, Na+, K+.
Neural stimulus - signals from the nervous system
hormonal stimulus
hypothalamus secretes a hormone that stimulates the anterior pituitary gland to secrete a hormone that stimulate other endocrine glands to secrete hormones
humoral stimulus
low blood ca2+ levels stimulates parathyroid glands to secrete parathyroid hormone
neural
preganglionic sympathetic fibres stimulate adrenal medulla to secrete adrenalin and noradrenalin
chemical classes of hormones
steroid hormones made from cholesterol
are lipid-soluble
amino acid based hormones amino acids, peptides or proteins
are lipid insoluble
hormones alter target cell activity
-control the rate of chemical (metabolic) reactions
-facilitate the transportation of substances into and out of cells
-regulate fluid and electrolyte balance, blood pressure, reproductive functions, development and growth
-maintain homeostasis
Hypothalamus-Posterior Pituitary
hypothalamic neurons produce oxytocin and (ADH).
hypothalamic-hypophyseal tract, which transport hormones to the posterior pituitary
When stimulated neuron secrete hormones into bloodstream
ADH
blood Na+ levels increase above the normal range, and/or blood volume and blood pressure decrease below the normal range.
targets the kidneys decreases urine output by stimulating the kidneys to return more water back into the blood
also cause the vasoconstriction of arterioles which helps increase blood pressure.
Oxytocin
stretching of the uterus during labour and the suckling action of the infant during breastfeeding.
stimulates the contraction of uterine smooth muscle cells during labour and the ejection of milk from the mammary glands during breastfeeding.
Hypothalamus-Anterior Pituitary
When stimulated, hypothalamic neurons secrete releasing/inhibiting hormones into the hypophyseal portal system
Hormones travel to the anterior pituitary
hypothalamic hormones stimulate/inhibit secretion of anterior pituitary hormones
FSH & LH
(GnRH) stimulates them, they target the male and female gonads
prolactin
Prolactin-inhibiting hormone controls the the secretion of PRL, targets the mammary glands and stimulates milk production
ACTH
CRH stimulates it, targets the adrenal cortex to secrete the hormone cortisol
TSH
TRH stimulates it, targets the thyroid gland to secrete the thyroid hormones
GH
GH-RH & GHIH
GH stimulates cells in the liver, skeletal muscles and bones to secrete insulin-like growth factors (IGFs), which stimulate the actions required for growth
Thyroid glands
base of the throat- secreted by TSH
increase BMR, body heat, HR and force of contraction by increasing the number of beta-adrenergic receptors on cardiac muscle cells
promotes growth of muscles and bones and nervous system development
Calcitonin
Calcitonin is secreted by the parafollicular cells of the thyroid gland when blood Ca2+ levels increase above the normal range.
targets bone, and decreases blood Ca2+ to normal levels by inhibiting the activity of osteoclasts stimulating calcium uptake from the blood into bone
Parathyroid Hormone
secreted by the parathyroid glands when blood Ca2+ levels decrease below the normal range. targets bone, kidneys and small intestines, and increases blood Ca2+ to normal levels by stimulating: bone-resorbing osteoclasts, the kidneys to return more Ca2+ to the blood
EPO
secreted by the kidneys when blood oxygen levels drop below their normal range, targets the bone marrow and stimulates the production of red blood cells.
Cortisol
from the adrenal cortex is stimulated by the anterior pituitary hormone, ACTH. is an important metabolic hormone that helps the body resist stressors by increasing blood glucose, fatty acid and amino acid levels as follows
Aldosterone
an increase in blood K+ levels or Angiotensin II. maintains blood K+ and Na+ levels within their normal ranges by stimulating the kidneys to: remove more K+ from the blood return more Na+ back into the blood
Adrenaline and Noradrenaline
sympathetic division of the autonomic nervous system. prolong the fight-or-flight response By binding to the alpha (α) or beta (β) adrenergic receptors on target cells, adrenaline and noradrenaline
insulin
pancreatic beta cells when blood glucose levels increase above the normal range (4-8mmol/L). decreases blood glucose to normal levels stimulates body cells to uptake glucose from the blood, targets the liver to inhibit the production of glucose from amino acids and glycerol targets the liver and skeletal muscle to inhibit the breakdown of glycogen to glucose
Glucagon
pancreatic alpha cells when blood glucose levels decrease below the normal range. increases blood glucose to normal levels by stimulating the liver to breakdown stored glycogen to glucose
produce glucose from amino acids and glycerol
release glucose into the bloodstream
Oestrogen
anterior pituitary hormones, FSH & LH.
Oestrogen targets female reproductive organs to promotes their growth and maturation, targets the uterus to regulate the menstrual cycles and promotes the development of female secondary sex characteristics
Progesterone
anterior pituitary hormone, LH.
prepares the uterus for pregnancy and helps maintain the pregnancy. Together with oestogen it also regulates the menstrual cycle
Testosterone
stimulated by the anterior pituitary hormone, LH
promote their growth and maturation, targets the testes to stimulate sperm production promotes the development of male secondary sex characteristics
