week 2 quiz review Flashcards
review of negative feedback loop
stimulus will produce a change in normal homeostasis; this is detected by sensors and this input travels along the afferent pathway to the control centre; control centre creates an output which is sent along the efferent pathway to an effector; the response of the effector decreases the original stimulus, thus maintaining homeostasis
stimulus
a change great enough to disrupt normal homeostasis conditions
receptors
contain sensors that detect the stimulus and create generators or receptors potentials; this information is sent along the afferent pathway to the control centre
bladder at rest
motor neurons are firing, detrusor muscle is relaxed, and internal and external sphincters are contracted
what parts of the bladder are controlled by the parasympathetic system?
the detrusor and the internal sphincters
what parts of the bladder are controlled by the somatic system?
the external sphincter
where is the micturition centre located?
the sacral spinal cord
what is the smooth muscle of the bladder
detrusor muscle and internal urethral sphincter
what does the contraction of the detrusor muscle do?
makes the bladder small, thus increasing pressure inside the bladder
what are the motor neurons synapsing with during bladder at rest?
the sphincter muscles, causing these structures to stay contracted
bladder when full
sensory receptors detect stretch and send this sensory input to sacral spinal cord; this causes two motor pathways to be stimulated by the parasympathetic system, the first is for the detrusor muscle to contract and the second is the relaxation of the internal sphincter; also during this time the firing of motor neurons ceases
what is the stimulus for ADH secretion?
high blood osmolarity and when water reabsorption is low
where and what are the receptors for ADH feedback loop?
the osmoreceptors in the hypothalamus
what releases ADH?
posterior pituitary gland which is controlled by the hypothalamus
where does ADH act?
in the late DCT and collecting ducts
what does ADH bind to?
V2 receptors on the basolateral membrane of collecting duct cells
what cells does ADH act on?
principal cells
result of ADH feedback loop
decreased plasma osmolarity and increased facultative water reabsorption
what produces renin?
the juxtaglomerular apparatus
what detects low blood pressure
JGA and baroreceptors in the carotid sinus
what is renin?
an enzyme that causes the conversion of angiotensinogen to angiotensin I
where is aldosterone released from?
the adrenal cortex
ANG II effects
increased sympathetic activity, vasoconstriction, increased Na and H20 reabsorption, ADH secretion via posterior pituitary gland, and aldosterone secretion
why is ANG II associated with sympathetic system?
because this systems helps to increase blood pressure by increasing heart rate and blood pressure by vasoconstriction; sympathetic system also causes the release of norepinephrine when ANG II binds to AT1 receptors, causing vasoconstriction
when happens when blood pressure conditions are normal?
blood vessels are dilated and intrinsic controls override extrinsic controls
what does ANG II bind to?
AT1 receptors
how does ANG II cause increased tubular reabsorption of Na and Cl?
through increasing Na, Cl, and K channels in the CT; also causes increased activity of the Na/H antiporter, as well as the Na/Cl symporter
what does aldosterone do in simple terms?
causes increased activity of the principal cells of the collecting ducts; increases Na, Cl, and K channels here
what does aldosterone bind to?
mineralocorticoid receptors within the cell cytoplasm
afferent vs efferent arteriole during normal conditions
afferent is typically larger in diameter than the efferent
afferent and efferent arterioles if BP needs to increase
afferent will constrict, allows decreased GFR
afferent and efferent arterioles if BP needs to decrease
efferent will constrict, allows increased GFR
what kind of hormone is aldosterone?
a steroid hormone
where does aldosterone act?
mainly in the CT (principal cells)
what is the primary purpose of aldosterone?
to increase the activity of the Na/K pump; but also increases sodium, potassium, and chloride channels
ANP
released when blood pressure is high from the atria of the heart; functions to inhibit renin and therefore decreased sodium reabsorption
what is a diuretic?
a type of drug that causes the kidneys to make more urine, decreasing blood volume and pressure as a result
transport proteins involved in aldosterone mechanism?
Na/K pump, Na channels, K channels, Cl channels, and aquaporins
where do osmotic diuretics work?
in the PCT