L1 Flashcards
the master endocrine organ is _______
the hypothalamus
The _______ modifies the stimulation of endocrine glands and their negative feedback mechanisms. Can
also override normal endocrine controls.
nervous system
classical endocrine glands
pituitary, thyroid,
parathyroid, adrenal, pineal, and thymus
non-classical endocrine glands
adipose cells, cells in walls of small intestine, stomach, kidneys, and heart
true or false: endocrine system uses ducts.
false—endocrine system is ductless, hormones are secreted into the blood
neurosecretory cells
neurons that secrete hormones, typically activated by an electrical signal. most are found in the hypothalamus.
three control mechanisms of endocrine glands
hormonal - chemical stimulus, gland is activated by another hormone
humoral - changing blood levels of certain ions (Ca2+) stimulates hormone release
neural - nerve impulses stimulate hormone release
key components of endocrine regulatory system
- detector of homeostatic imbalance
- coupling mechanism to activate hormone secretion
- secretory apparatus
- hormone
- end-organ responds to hormone
- detector recognizes hormonal effect has occurred
- hormone removed from cell
- synthetic apparatus to replenish the hormone in the secretory cell
Substance are
secreted in [small / large]
amounts by the cells
of endocrine gland.
small
A single gland may
secrete [only one / multiple]
hormones
multiple
what chemical components are hormones made of
amines (from tyrosine/tryptophan), peptides/proteins, glycoproteins, steroids (from cholesterol), eicosanoids
eicosanoids
small molecules synthesized
from fatty acid substrates
(e.g. arachidonic acid)
located within cell membranes
Include prostaglandins.
true or false: the same hormone may have different effects on target cells that have different receptors for the hormone
true
true or false: hormones have the same functions across species
false
ex: prolactin –> milk production in mammals but fat metabolism in birds
four types of endocrine disorders
- hypo-secretion
- hyper-secretion
- hypo-responsiveness
- hyper-responsiveness
primary vs secondary hypo-secretion
primary - malfunction in organ that produces hormone, deficiency in resources for hormone production
secondary - deficiency in tropic “regulatory” hormone
three pathological mechanisms of endocrine disease
hormone excess, hormone deficiency, hormone resistance (i.e., type 2 diabetes = insulin resistance)
Homeostasis vs. Allostasis
Homeostasis: balance of systems essential for life (pH, body temperature,, [glucose], pO2
Allostasis: changes in the body that keep homeostatic systems in balance chronically (catecholamines, HPA axis, cytokines)
Allostasis is an extension of homeostasis. When the body encounters a prolonged stressor, it may need to deviate from its usual homeostatic parameters in order to maintain overall stability. Over time, allostatic adaptations can become maladaptive and lead to health problems.
negative vs positive feedback
NEGATIVE FEEDBACK: Mechanism that RESTORES abnormal values to normal. Reverses a change
POSITIVE FEEDBACK: Mechanism that MAKES abnormal values MORE ABNORMAL. Strengthens or reinforces a change
true or false: most hormones exert profound effects on their target cells and tissues at very low concentrations
true - it’s because the affinity of hormones to their specific receptors is typically very high so not much is needed
describe the first recorded endocrine experiment
Arnold BERTHOLD in 1849. Compensatory hypertrophy.
he removed the testes from roosters (creating “capons”) and then re-implanted them, demonstrating that the testes produced a substance responsible for male characteristics. The roosters that had their testes re-implanted developed normal male characteristics, like crowing, despite being castrated.
first described hormone
In 1902, William Bayliss and Ernest Starling found that in response to the delivery of acidic fluid from the stomach to the intestine, SECRETIN, an internal secretion, was released into the blood from the endocrine cells of the duodenum.
epinephrine alpha receptor causes ______; beta receptor causes ______
vasoconstriction in intestinal blood vessels; vasodilation in skeletal blood vessels
