Lecture 17: Micturition and Glomerular Filtration Flashcards
Once initiated, the micturition is ______
self-regenerative
As the bladder continues to fill, micturition reflexes occur more _____ and are more _____
often; powerful
What are functions of the nephron?
get rid of waste material regulate water and electrolyte balance regulate body fluid osmolarity regulate arterial pressure regulate acid base balance secretion, metabolism, and excretion of hormones gluconeogeneis
How does the nephron regulate arterial pressure long term?
excrete variable amounts of sodium ion and water
How does the nephron regulate arterial pressure short term?
secrete hormones and vasoactive factors such as renin
What are the three processes that determine the rate at which different substances are excreted in the urine?
filtration
reabsorption
secretion
What is the urinary excretion rate?
filtration rate - reabsorption rate + secretion rate
What are the major components of the glomerular filtrate?
water
ions
glucose
urea
What is the filtration fraction equation?
GFR/ renal plasma flow
What are the layers of the filtration barrier?
endothelium
basement membrane
podocytes
What is the glomerular filtration rate determined by?
balance of hydrostatic and colloid osmotic forces acting across capillary membrane
What is the GFR?
125 ml/min = 180 L/day
Water has a filterability of _____
1.0
What are some of the diseases that lower glomerular capillary filtration coefficient?
chronic uncontrolled hypertension and diabetes mellitus
What is minimal change nephropathy?
loss of negative charge on the basement membrane
What is hydronephrosis?
distension and dilation of renal pelvis and calyces
What is the GFR equation?
k1 x net filtration pressure
k1= capillary filtration coefficient
What are factors that influence glomerular capillary colloid osmotic pressure?
arterial plasma colloid osmotic pressure
filtration fraction
What are factors that increase glomerular colloid osmotic pressure?
increasing filtration fraction
An increase in arterial pressure ______ glomerular hydrostatic pressure and _____ GFR
increases; increases
An increase in afferent arteriolar resistance ______ glomerular hydrostatic pressure and _____ GFR
decreases; decreases
An increase in efferent arteriolar resistance ______ glomerular hydrostatic pressure and _____ GFR
increases; increases (slightly)
Renal blood flow equation
(renal artery pressure- renal vein pressure) / (total vascular resistance)
All blood vessels of the kidney are innervated by _____ system
sympathetic
What does strong activation of renal sympathetic nerves do?
constrict renal arterioles
decrease renal blood flow and GFR
What mechanisms control GFR consistency?
sympathetic system
hormones
What is endothelin’s role in controlling GFR?
released by damaged vascular endothelial cells of the kidneys and other tissues
What is angiotensin II’s role in controlling GFR?
constricts efferent arterioles
formed usually in situations with decreased arterial pressure or volume depletion
afferent arterioles seem to be protected against the effects of angiotensin II
What is nitric oxide’s role in controlling GFR?
derived from endothelial cells
basic level helps maintain renal vasodilation
What are the roles of prostaglandins and bradykinin in controlling GFR?
vasodilators that may offset effects of sympathetic and angiotensin II vasoconstrictor effects
What does auto regulation refer to?
relative constant of GFR and renal blood flow
What is the primary function of auto regulation?
maintain relatively constant GFR
allow precise control of renal excretion of water and solutes
prevent relatively large changes in GFR and renal excretion that would otherwise occur with changes in blood pressure
What is normal daily fluid excretion?
1.5 L/day
What are the two components of tubuloglomerular feedback mechanism for auto regulation?
an afferent arteriolar feedback mechanism
an efferent arteriolar feedback mechanism
If GFR decreases, there is a slow flow rate in loop of Henle, and a ______ reabsorption or sodium and chloride ions into ascending limb, and ______ in sodium chloride at macula densa
increase; decrease
A decrease in NaCl results in signal from macula densa which results in:
_______ resistance to blood in afferent arterioles
_____ renin release from JG cells
_______ angiotensin II
________ efferent arteriolar resistance
decrease; increase; increase; increase
