Hormones Flashcards
What are hormones
-Enable communication between cells
-Secreted by Endocrine glands
-Carried in bloodstream to target specific regions, (other endocrine glands, organs, cells, the brain)
Neural & Endocrine communication Similarities
-Produce chemicals stored for later release
-Stimulated to release chemicals
-Some chemicals act as hormones & neurotransmitters
-React with specific receptors
Neural & Endocrine communication Differences
-Neural communication is fixed between channels to precise locations; hormonal signalling is more generalised
-Neural messages are very rapid; hormonal communication is slower and prolonged
-Neurotransmitters travel across synapses; Hormones travel through blood
-Some neural communication is voluntary control (muscle etc), hormone release is not
Functions of Hormones
-Excite and set things in motion and regulate:
-growth & development
-reproduction
-metabolism
-homeostasis
-control of internal organs
Negative Feedback
-Output from a gland is responsible for preventing further release of more hormones
Pineal Gland
-Melatonin, crucial for sleep regulation
-Entrainment- matching a physiological event to an environment oscillation e.g. low levels during day, increase at 8pm, peaks at midnight, decrease over night and dip again at daytime
Hypothalamus
-located at base of brain
-hypothalamic nuclei make hypothalamic releasing hormones that stimulate/inhibit hormone release from pituitary gland
Pituitary Gland
-Tropic hormones, influence release of hormones from other glands
-Anterior, controlled by hypothalamic releasing hormones
-Posterior, controlled by nerve stimulation from hypothalamus
Posterior Pituitary Gland - ADH
-Anti-Diuretic Hormone
-Stimulates re-absorption of water by kidneys (conserves water)
-stimulates vasoconstriction (lower BP in response to stress)
-Caffeine, alcohol block vasopressin (ADH)
Posterior Pituitary Gland - Oxytocin
-Causes muscle contraction in uterus and stimulates ejection of breast milk
-Elevated levels during sexual arousal
-Levels respond to social stimulation causing anti-stress effects
-Those who feel socially supported have higher levels of oxytocin
Anterior Pituitary Gland - Growth Hormone
-Helps with metabolism, fat storage, glucose regulation
Anterior Pituitary Gland - Thyroid stimulating hormone
-Stimulates release of thyroxine by thyroid gland
-Regulates metabolic rate - heart/digestive functions
Anterior Pituitary Gland - Gonadotrophins
-Sex hormone release
-Luteinizing hormone, increases progesterone and testosterone
-Follicle stimulating hormone, increase oestrogen and sperm
Anterior Pituitary Gland - ACTH
Adrenocorticotropic Hormone
stress hormone release
Anterior Pituitary Gland - Prolactin
-Promotes tissue development in breasts during pregnancy and stimulates milk production after birth
-Also plays a part in sexual desire potentially
Adrenal Gland
-Sits on top of kidneys
-Medulla (inside), responds to nerve stimulation from hypothalamus
-Cortex (outside), responds to ACTH from ant. pit.
Adrenal Medulla
-Noradrenaline & Adrenaline
-Increase heart rate
-Constrict peripheral blood vessels
-Glucose release
-Increase blood flow to muscles etc, short term preparation for stress
-Fight/Flight
Adrenal Cortex
-Sex hormones, Androgens and Oestrogens
-Mineralocorticoids, Aldosterone, Helps kidneys retain sodium excrete potassium, maintain blood pressure, maintain salt/water balance in body
-Corticosteroids, Mainly cortisol, maintains essential responses during stressful events
Pancreas
-Insulin and glucagon
-Low blood sugar and stress, pancreas secretes glucagon and causes liver release glucose
-High blood sugar, release insulin, excess glucose taken by fat cells
Testes
-Release androgens
-Secreted in small amounts from adrenal cortex so also produced by women
-Main is testosterone
-production begins during foetal development
-Burst at puberty stimulates secondary male characteristics
Growth & development of male reproductive structures
Increased skeletal & muscle growth
enlargement of larynx & voice change
Increase body hair
sexual drive
Ovaries
-Female sex hormones, oestrogens
-also produced by men in small amounts (adrenal cortex)
-Onset of puberty releases
Estradiol, breast development, distribute fat, maturation of uterus & vagina
Progesterone - thickens lining of uterus in pregnancy
Both - stimulate changes in uterus during cycle, sexual behaviour
Hormones & Behaviour
-remove source of hormone
-artificially add the hormone
-measure behaviour associated with hormone
castration/ovariectomy should have an effect on sexual behaviour
Somatic intervention
