endocrine I: central hormones Flashcards
(40 cards)
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
