endocrine Flashcards
direct communication
exchange of ions and molecules between adjacent cells across gap junctions; occurs between two cells of the same type
autocrine communication
messages affect the same cells that secrete them
Paracrine communication
chemical signals transfer information from cell to cell within a single tissue
endocrine communication
endocrine cells release chemicals (hormones) that are transported in the bloodstream; alters metabolic activities of target cells
synaptic communication
neurons release neurotransmitters at a synapse; leads to action potentials re that propagated along axons
pathway of light
Light enters the cornea then the aqueous humor, then the lens, then the vitreous body, and then the retina and then fovea centralis where the photoreceptors are located. Then the bipolar cells synapse with the ganglion cells which senses an action potential to the optic chiasm to the thalamus to the cortex
pathway of light from sensory receptor to brain
Photon hits rhodopsin, retinal changes it shape and separates from opsin, opsin activates the closure of sodium ion channels, neurotransmitter goes away, bipolar cells releases graded potential to ganglion cell, action potential goes down ganglion cells and tells brain that it has seen light.
pathway of sound
Auricle, external acoustic meatus, tympanic membrane, auditory ossicles, oval window, vestibule/semicircular canals, cochlea, cochlear nerve
The hearing receptor is the cochlea
Cochlear nerve, medulla oblongata, pons, inferior colliculi of midbrain, thalamus, auditory cortex of temporal lobe
pathway of equilibrium receptors to the brain
sensory neurons in the vestibular ganglia monitor hair cells of the vestibular complex, vestibular nerve formed from ganglia fibers, CN VII synapse within vestibular nuclei at boundary between pons and medulla oblongata
pathway for olfaction
odorant binds to g-coupled receptor, afferent fibers leave olfactory epithelium, reach olfactory bulbs of cerebrum, travels along olfactory tract to olfactory cortex, hypothalamus and limbic system; ONLY SENSORY INFO THAT REACH CEREBRAL CORTEX DIRECTLY
pathway for gustation
anterior ⅔ tongue CN 7 facial nerve, rest of tongue CN 9 glossopharyngeal, bitter taste/ gag reflex CN 10 vagus nerve, spicy temp CN 5 trigeminal nerve
amino acid derivative
Amino acid derivatives
Small molecules structurally related to amino acids
Derivatives of tyrosine
Thyroid hormones
Catecholamines (epinephrine, norepinephrine, and dopamine)
Derivatives of tryptophan
Serotonin and melatonin
peptide hormones
Chains of amino acids
Most are synthesized as prohormones
Inactive molecules converted to active hormones before or after they are secreted
Glycoproteins (ex: TSH LH FSH)
Small proteins (<200 aa)
Includes all hormones secreted by hypothalamus, heart, thymus, digestive tract, pancreas, posterior lobe of the pituitary gland, etc…
lipid derivatives
Steroid hormones- derived from cholesterol
Include
Androgens from testes in males
Estrogen and progesterone from ovaries in females
Corticosteroids from adrenal cortex
Calcitriol from kidneys
Bound to specific transport proteins in the plasma
Remain in circulation longer than peptide hormones
down-regulation
decrease in number of hormone receptors; when levels of a particular hormone are high, cells become less sensitive to it
up-regulation
increase in number of hormone receptors; when levels of a particular hormone are low, cells become more sensitive to it
humoral stimuli
change in extracellular fluid
triggers hormonal secretion
hormonal stimuli
arrival or removal of hormone
triggers hormonal secretion
neural stimuli
neurotransmitter
triggers hormonal secretion
hypothalamus
Regulates functions of the pituitary gland
Synthesizes antidiuretic hormone (vasopressin) (ADH) and oxytocin (OXT) and transports them to posterior pituitary gland for release
Secretes regulatory hormones that control secretory activity of anterior pituitary gland
Contains autonomic centers that exert direct control over adrenal medulla
thyroid gland
regulates metabolism in the body by the production of thyroid hormones
parathyroid gland
Parathyroid hormone (PTH) or parathormone
Secreted by parathyroid (principal) cells in response to low concentrations of Ca2+ in blood
Antagonist for calcitonin
Stimulates osteoclasts
Accelerates mineral turnover and Ca2+ release
Enhances reabsorption of Ca2+ by kidneys, reducing urinary losses
Stimulates formation and secretion of calcitriol by kidneys
outer zona golmerulosa
Mineralocorticoids ex: Aldosterone
Stimulates conservation of sodium ions and elimination of potassium ions
Increases sensitivity of salt receptors in taste buds
Secreted in response to
Drop in blood Na+, blood volume, or blood pressure
Rise in blood K+ concentration
middle zona fasciculata
Glucocorticoids ex: cortisol, corticosterone, and cortisone
Secretion is regulated by negative feedback
Glucocorticoids have an inhibitory effect on the production of
Corticotropin-releasing hormone (CRH) in the hypothalamus
ACTH in the anterior pituitary
Accelerate glucose synthesis and glycogen formation, especially in liver
Have anti-inflammatory effects
Inhibit activities of white blood cells and other components of immune system
