Introduction to Urinalysis Flashcards
The kidneys continuously form urine as an _____ of ______.
Ultrafiltrate of plasma
Reabsorption of water and filtered substances essential to body function converts approximately ________ of filtered plasma to the average daily urine input of _______
170,000 mL
1200 mL
Urine is normally ____ and _____
95% water and 5% solutes
A metabolic waste product produced in the liver from the breakdown of protein and amino acids, accounts for nearly half of the total dissolved solids in urine.
Urea
The major inorganic substances dissolved in urine is
chloride, followed by sodium and potassium
The organic substances in urine include primarily of
creatinine and uric acid
It depends on the amount of water that the kidneys excrete
Urine volume
Primary components in normal urine
urea
creatinine
uric acid
chloride
sodium
potassium
phosphate
ammonium
calcium
Primary components in normal urine:
Primary organic component. Product of protein and amino acid metabolism
Urea
Primary components in normal urine:
Product of creatinine metabolism by muscles
Creatinine
Primary components in normal urine:
Product of nucleic acid breakdown in food and cells
Uric acid
Primary components in normal urine:
Primary inorganic component. Found in combination with sodium (table salt) and many other inorganic substances
Chloride
Primary components in normal urine:
Primarily from salt, varies by intake
Sodium
Primary components in normal urine:
Combined with chloride and other salts
Potassium
Primary components in normal urine:
Combines with sodium to buffer the blood
Phosphate
Primary components in normal urine:
Regulates blood and tissue fluid acidity
Ammonium
Primary components in normal urine:
Combines with chloride, sulfate, and phosphate
Calcium
Situated primarily in the renal cortex
Cortical nephron
Primarily responsible for the removal of waste products
Cortical nephron
Its primary function is urine concentration
Juxtamedullary nephron
A non-selective filter of plasma substances
Glomerulus
Is the blood volume delivered to the kidneys/unit time
Renal blood flow
the primary step in making urine
Glomerular filtration
It is the renal process that involves with the filtration of ecxess fluid & waste products out of the blood into the collecting tubules, that facilitates their allow elimination
Glomerular filtration
Is the best test to measure the level of renal function & determine the stages of renal diseases
Glomerular filtration rate
Is the process by which water & solutes are removed from the tubular fluid and transported into the blood
Tubular reabsorption
Is a passive process whereby drugs are reabsorbed into the systemic circulation from the lumen of the distal tubules
Tubular reabsorption
It is the transfer of materials from peritubular capilllaries to the renal tubular lumen
Tubular secreyion
Is caused mainly by passive diffusion & active transport
Tubular secretion
It originates from the aorta and provides blood supply to the kidneys
Renal artery
total renal blood flow
1200 mL/min, or 600 mL/min (ave body size 1.73 m2)
total renal plasma flow
600 to 700 mL/min
Short version of renal blood flow:
Renal artery –> afferent arteriole –> efferent arteriole –> proximal convoluted tubule capillaries –> vasa recta/loop of henle –> distal convolutes tubule capillaries –> renal vein
its function is primary reabsorption
Proximal convolute tubule
Site where finaal urine concentration takes places
Distal convoluted tubule
Site where major exchanges of water and salts
Vasa recta
approximately _______ or ________ of the renal plasma is filtered through the glomeruli forming the ultrafiltrate
1/5 or 120 mL/min
Has a similar composition with blood plasma yet it is normally free of protein except for about 10 mg/dL of low molecular-weight protein
Ultrafiltrate
Composition of the filtered products:
water, glucose, electrolytes, amino acids, urea, uric acid, creatinine, ammonia
refers to the movement of water & small solutes, (coming from the blood) flowing through the glomerulus, across the porous filtration membrane
GLOMERULAR FILTRATION
is proportional to the body size varies with sex & age
glomerular filtration rate (GFR)
is used to monitor the progression of kidney diseases
glomerular filtration rate (GFR)
is an important indicator of renal function
glomerular filtration rate (GFR)
The 3 cellular layers that the plasma filtrate must pass through:
- the capillary wall membrane
- the basement membrane (basal lamina)
- the visceral epithelium of Bowman’s capsule
Filtration is enhanced by the presence of _________ resulting from the smaller size of the efferent arteriole & the glomerular capillaries.
hydrostatic pressure
↑ing or ↓ing the afferent arteriole size leads to the development of a _______________ that can keep the glomerular BP at a relatively constant rate regardless of systemic BP fluctuations
juxtaglomerular apparatus autoregulatory mechanism
prevent a marked ↓in blood flowing through the kidney, hence preventing an ↑ in the blood level of toxic waste products
afferent arterioles dilation & efferent arterioles constriction during BP drops
prevents over-filtration or glomerular damage
afferent arteriole constriction during BP elevations
Where does Glomerular filtration takes place?
Renal corpuscle
tubular reabsorption & tubular secretion happen all along the
renal tubule & collecting duct.
controls blood flow regulation to & within the glomerulus
Renin-Angiotensin-Aldosterone System (RAAS)
Is involved in regulating urine concentration & volume
Renin-Angiotensin-Aldosterone System (RAAS)
is sensitive to BP changes & plasma sodium content
Renin-Angiotensin-Aldosterone System (RAAS)
it controls aldosterone secretion
Renin-Angiotensin-Aldosterone System (RAAS)
is an enzyme (aka an angiotensinogenase) synthesized by the juxtaglomerular cells in the kidneys
Renin
is responsible in converting angiotensinogen, (a plasma protein produced by the liver), into angiotensin I
Renin
present in the lungs converts the passing angiotensin I into its active form angiotensin II
angiotensin converting enzyme (ACE)
the sodium-retaining hormone
Aldosterone
produced in the outer section (cortex) of the adrenal glands
Aldosterone
is a major mineralocorticoid that aids in the regulation of homeostasis of 2 mineral ions, namely sodium ions (Na+) and potassium ions (K+)
Aldosterone
it promotes H+ excretion in the urine; this acid removal from the body can help prevent acidosis (blood pH below 7.35)
Aldosterone
