endocrine I: central hormones Flashcards
what does the endocrine system include?
-hypothalamus
-pituitary
-thyroid/parathyroid
-adrenals
-pancreas
-ovaries/testes
how is the body chemically regulated?
hormones are made in glands and transported by blood; made for long-distance target tissues and activates physiological responses
what does hormone half-life indicate?
the length of a hormones activity
what are the controls of hormones?
water balance
blood volume
energy balance
appetite
digestion/circulation
growth/development
reproduction
RBC production
stress management
what are tropic vs. non-tropic hormones?
tropic: act on other endocrine glands. they control hormone secretion; ant. pituitary and hypothalamus
non-tropic: acts on effector organs
what are neuro-secretory cells?
they secrete neuro-hormones (or neuro-peptides)
-adrenal medulla; catecholamines
-hypothalamus; posterior pituitary
what are the 3 classifications of hormones?
-peptide; protein
-steroid; cholesterol
-amine; tryptophan/tyrosine (amino acids)
preprohormone vs. prohormone vs. hormones?
-prepro=large and INactive
-pro=post-translational modification
-hormone=final cuts before it exits cell as an active hormone; travel freely in blood but CANNOT pass the cell membrane (needs a receptor) and it has a short half-life (short length of active time)
how do hormones bind?
-enzyme activation
-opens channels
-secondary messenger systems
what are the features of peptide hormones?
-hydrophilic (water soluble)
-free to travel in blood but CANNOT pass the lipid membrane
-moves via membrane receptor/secondary messenger response
-quick acting and short half-life
-examples are glucagon, calcitonin, insulin
what are the features of steroid hormones?
-cholesterol derived
-lipophilic and can enter target cell easily but need to be bound to a protein to travel freely in the blood
-cytoplasmic or nuclear receptors
-activate DNA for protein synthesis
-slower acting but have a longer half-life
-examples are cortisol, estrogen, and testosterone
what are the features of amine hormones?
-ring structure derived from one of two amino acids
-tryptophan; ie melatonin
-tyrosine; ie thyroid hormones, catecholamines such as norepi/epinephrine and dopamine
what do catecholamines and thyroid hormones behave similarly to?
-catecholamines act similarly to peptides
-thyroid hormones act similarly to steroids
what 3 rates do blood hormone levels depend on ?
rates of:
-hormone secretion
-hormone degeneration
-hormone excretion (kidneys)
what are 3 possible hormone interactions?
-synergism
-permissiveness
-antagonism
what are synergism interactions?
-multiple stimuli that is more effective that adding more strength of one
ie: glucagon, epi, and cortisol
what are permissiveness interactions of hormones?
-it is when a second hormone is needed to get a full expression
ie TH and epinephrine; TH increases the number of receptor sites for epinephrine to be effective
what are antagonism interactions of hormones?
-pairs of hormones that have opposing effects
ie insulin is opposed by glucagon
what is the hormonal interaction between TH and epinephrine?
it has a one-sided effect. Th will help increase the effect of epinephrine but epinephrine will not do the same for TH.
what is negative feedback?
it is self-regulating hormone levels
-turns off response homeostatically
what are the 3 levels of endocrine control?
-hypothalamic=from the CNS
-pituitary stimulation=hypothalamic trophic hormones
-endocrine gland stimulation=pituitary trophic hormones
what can hormone secretion be affected by?
-emotional state
-disease state
-sleep
-diet
-stress
-body cycles (menstrual, circadian rhythms)
what is primary HYPOsecretion?
too little hormone is secreted due to gland abnormality
-can be genetic, dietary, chemical/toxic, auto-immune, or diseases causing it
what is secondary HYPOsecretion?
the gland itself is normal but too little normal is secreted due to a lack of a tropic hormone
what is primary HYPERsecretion?
too much hormone is being secreted due to abnormalities within the gland
what is secondary hypersecretion?
excessive stimulation from outside of the gland itself is causing oversecretion
what does the hypothalamus do?
-maintains homeostasis
-controls ANT. pituitary; which then effects other endocrine glands
how is the anterior pituitary stimulated?
anterior pituitary hormones are stimulated to be secreted by one or more hormones from the hypothalamus
what are the hormones stored in the neurohypophysis and how are they released?
Oxytocin and ADH are made in the hypothalamus and then STORED in the neurohypophysis aka POST. pituitary
-when a neuron is excited, these hormones are released
what is the function of oxytocin?
-stimulates uterine contractions in childbirth
-promotes milk ejection during lactation
what is ADH and how does it work?
ADH (anti-diuretic hormone/vasopressin) is released if blood volume is low or blood osmolarity is high
-ie when dehydrated
it works by increases the water reabsorption in the kidneys a nd decreasing urine output
what is diabetes insipidus?
it is a decreased amount of ADH/vasopressin
-there is excessive polyuria
-leads to excessive urination and hypotension, dizziness, and constipation
-can be treated by vasopressin replacement
what are the 6 hormones secreted by the adenohypophysis?
the adenohypophysis aka the ANT. pituitary secretes
-FSH
-LH
-GH
-TSH
-Prolactin
-ACTH
FSH vs. LH
FSH promotes egg and sperm production
LH secretes estrogen and testosterone from the gonads (ovulation in women)
where does TSH and ACTH act on?
TSH acts on the thyroid to promote TH secretion
ACTH acts on the adrenal cortex to promote cortisol secretion
what is the one non-tropic hormone from the ANT. pituitary?
prolactin
-acts on the mammary glands to develop breasts and milk production
what does GH stimulate?
-causes the liver to release IGF; somatomedins
-stimulates protein synthesis and cell division for increased muscle and thickening/lengthening of bones
what are the other )metabolic) effects of GH?
-increases fatty acids in blood from the breakdown of fat in adipose tissue
-increases blood glucose as glucose uptake by the muscles is decreased
what is fetal vs. postnatal growth?
-fetal=promoted by hormones from placenta and GH has NO role
-postnatal=first 2 years of life and it is GH controlled (just as in pubertal growth)
what is the function of the pineal gland?
-secretes melatonin and influences the body clock/antioxidant activity
