111 terms

BIOL 122 Chp 26 The Urinary System

Rob Swatski, Associate Professor of Biology at HACC York Campus (HACC, Central Pennsylvania's Community College) http://robswatski.virb.com/
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nephrology
the scientific study of the anatomy, physiology, and pathology of the kidneys
urology
the branch of surgery related to male and female urinary systems and the male reproductive system
metabolic wastes
include carbon dioxide, water, excess ions (H+ and HCO3-) and salts, N-containing wastes from the breakdown of proteins (ammonia, urea, uric acid, and creatinine)
renal capsule
deep layer that forms a barrier against trauma and maintains kidney shape
adipose capsule
a mass of fatty tissue protecting the kidney; holds it in place
renal fascia
thin, superficial layer of connective tissue that anchors kidney to surrounding structures and abdominal wall
nephroptosis
downward displacement of kidneys when fat material surrounding kidneys is reduced, causing them to become less securely anchored and drop inferiorly
renal hilum
entrance for renal artery and vein, ureter, nerves, and lymphatics
ureter
tube that carries urine from the kidney to the urinary bladder
urinary bladder
hollow, muscular sac that holds and stores urine
micturition
voiding the bladder; urination
urethra
tube leading from the urinary bladder to the outside of the body
renal cortex
outer region of the kidney
renal medulla
inner portion of the kidney
renal columns
areas of the renal cortex that run between the medullary pyramids
renal pyramids
cone-shaped structures located within the renal medulla that contain parts of the nephron
renal papilla
apex of renal pyramid
renal sinus
the space within a kidney that is adjacent to the renal medulla; contains calyces and the renal pelvis
nephron
the microscopic functional units of the kidneys that form urine
collecting duct
receives processed filtrate from many nephrons and transports it to the renal pelvis
minor calyx
a duct off the renal papilla that channels urine toward the major calyces
major calyx
formed from several minor calyces that merge together
renal pelvis
funnel-shaped reservoir that collects urine and passes it to the ureter
renal artery
supplies oxygenated blood to the kidneys; contains waste products that must be removed by the kidneys
renal vein
carries filtered deoxygenated blood away from the kidneys and back to the heart
segmental artery
this is the first branch of the renal artery after it enters the hilum of the kidney
afferent arteriole
the small artery that carries blood toward the capillaries of the glomerulus
glomerulus
a cluster of capillaries surrounded by a cup-shaped membrane called the Bowman's capsule; positioned between two arterioles
efferent arteriole
a smaller diameter artery that receives blood that has passed through the glomerulus
peritubular capillaries
the network of tiny blood vessels that surrounds the proximal and distal convoluted tubules in the kidney
vasa recta
the capillary branches that supply the loops of Henle in the medulla region of the kidney
interlobular vein
drains deoxygenated blood from the peritubular capillaries
renal corpuscle
the structure at the expanded end of a nephron that contains the Bowman's capsule and a glomerulus
renal tubules
the vessels in the kidney that are the sites of urine formation and the reabsorption of water, sugar, and salt
parietal layer
outer wall of the glomerular capsule composed of simple squamous epithelium
visceral layer
forms the inner wall of the glomerular capsule; has podocytes that wrap projections around a single layer of endothelial cells
capsular space
area in which fluid from the glomerular capillaries enters
filtration membrane
permits filtration of substances such as water, amino acids, glucose, NaCl, urea, uric acid, and many others; prevents filtration of most plasma proteins, blood cells, and platelets
podocytes
epithelial cells lining the Bowman's capsule
pedicels
the little foot-like processes of the podocytes that form filtration slits
fenestrations
the pores of the glomerular epithelial cells
glomerular filtration
the passive process where blood enters the glomerular capillaries and the resulting filtrate (consisting of water and solutes) enters the capsular space
tubular reabsorption
the active process where the filtrate enters the PCT and the reabsorbed water and useful solutes enter the blood through the peritubular capillaries
tubular secretion
the process where solutes in the blood (wastes, drugs, and excess ions) enter the filtrate in the DCT and collecting duct
cortical nephrons
these have glomeruli in the superficial renal cortex, and short loops of Henle that extend only into the outer region of the medulla; make up 80-85% of nephrons
juxtamedullary nephrons
these have glomeruli deep in the renal cortex, and long loops of Henle that extend deep into the renal medulla nearly to the renal papilla; their ascending limbs have thick and thin regions; enable kidney to secrete very dilute or very concentrated urine; make up the other 25-20% of nephrons
proximal convoluted tubule
the part of the nephron that is closest to the glomerular capsule; it reabsorbs most of the filtered substances
What epithelial tissue lines the PCT?
simple cuboidal epithelium with microvilli
loop of Henle
extends into the renal medulla, makes a hairpin turn, and returns to the renal cortex
What epithelial tissue lines the descending limb and thin ascending limb of the loop of Henle?
simple squamous epithelium
What epithelial tissue lines the thick ascending limb of the loop of Henle?
simple cuboidal epithelium
distal convoluted tubule
the part of the nephron that is farthest from the glomerular capsule; secretes most of the H+ and K+ ions into the tubular fluid
What epithelial tissue lines most of the DCT?
simple cuboidal epithelium
principal cells
these are found in the last part of the DCT and collecting duct and contain receptors for antidiuretic hormone (ADH) and aldosterone; contain Na+/K+ pumps that reabsorb Na+ and secrete K+
intercalated cells
these are found in the last part of the DCT and collecting duct and play a role in blood pH homeostasis; reabsorb K+ and HCO3- and secrete H+
juxtaglomerular apparatus
this consists of the macula densa and the JG cells, which help regulate blood pressure and rate of blood filtration within the kidneys (GFR)
macula densa
a group of cells in the ascending limb of the loop of Henle that are crowded together and act as chemoreceptors that monitor Na+ and Cl- concentration in the tubular fluid
juxtaglomerular cells
these are modified smooth muscle fibers found in the JGA that secrete the enzyme renin
solute excretion
glomerular filtration + secretion - reabsorption
glomerular filtrate
the fluid that enters the capsular space
filtrate fraction
the amount of blood plasma in the afferent arterioles of the kidney that becomes filtrate
urea
waste molecule produced by the liver resulting from the breakdown of proteins; 50% is reabsorbed
creatinine
waste molecule created by muscle metabolism; 0% is reabsorbed
glomerular blood hydrostatic pressure
the force of the blood pressure against the walls of the glomerulus; 55 mmHg
capsular hydrostatic pressure
the force of the filtrate fluid against the wall of the glomerular capsule; 15 mmHg
blood colloid osmotic pressure
the pressure due to the presence of proteins in the blood plasma; drives water in the filtrate to move back into the glomerulus; 30 mmHg
net filtration pressure
GBHP - CHP - BCOP
glomerulonephritis
damaged glomerular capillaries become so permeable that plasma proteins enter the filtrate, causing blood and proteins to be lost in the urine; causes an increase in NFP and leads to a loss of kidney function
glomerular filtration rate
the amount of filtrate formed in all of the renal corpuscles of both kidneys each minute
renal autoregulation
smooth muscle cells in the afferent arterioles contract in response to elevated BP; results in decreased blood flow to the glomerulus and GFR decreases to normal levels
tubuloglomerular feedback mechanism
a type of renal autoregulation where the macula densa provides feedback to the glomerulus and inhibits the release of nitric oxide (NO), causing the afferent arterioles to constrict which decreases GFR
neural regulation
stimulated by exercise, stress, or hemorrhage; smooth muscle around the afferent arterioles constrict, resulting in a decrease in GFR which reduces urine output and allows greater blood flow to other body tissues
renin angiotensin II
a type of hormonal regulation stimulated by decreased blood volume or blood pressure; results in the constriction of both afferent and efferent arterioles and a decrease in GFR
atrial natriuretic peptide
this hormone relaxes the mesangial cells of the glomerulus, which increases the capillary surface area for filtration, increasing GFR
paracellular reabsorption
tight junctions do not completely seal off interstitial fluid from tubule fluid; allows fluid to leak passively between adjacent tubule cells
transcellular reabsorption
occurs directly through an individual cell, across its cytosol, and through its basolateral membrane
secondary active transport
couples the movement of an ion down its electrochemical gradient to the "uphill" movement of a second substance against its electrochemical gradient
symporters
membrane proteins that move two or more substances in the same direction across a membrane
antiporters
membrane proteins that move two or more substances in opposite directions across a membrane
obligatory water reabsorption
a process in which water must follow the solutes (Na+, Cl-, glucose) that are reabsorbed; accounts for 90% of the water reabsorbed
facultative water reabsorption
a type of water reabsorption that is regulated by ADH; accounts for 10% of the water reabsorbed
glucosuria
glucose in the urine
diabetes mellitus
the most common cause of glucosuria, in which blood glucose level rises above normal because insulin activity is deficient
tubular fluid
what filtered fluid becomes upon entering the PCT
Na+ glucose symporters
helps reabsorb 100% of glucose; located in the apical membrane of the PCT cells
glucose facilitated diffusion transporters
helps reabsorb 100% of glucose; located in the basal membrane of the PCT cells
Na+ H+ antiporter
causes Na+ to be reabsorbed and H+ to be secreted; located in the apical membrane of the PCT cells
aquaporin 1
transport proteins located in the apical and basolateral membranes of PCT cells and the descending limb of the loop of Henle, making them more permeable to water
Na+ K+ 2Cl- symporters
transport proteins located in the thick ascending limb of the loop of Henle that help in solute reabsorption
parathyroid hormone
this causes Ca+2 channels in the apical membranes of cells in the early DCT to open, resulting in an increased reabsorption of Ca+2 into the blood
aldosterone
stimulates the reabsorption of Na+ and secretion of K+ in the principal cells of the last part of the DCT and CD; increases blood volume
antidiuretic hormone
this increases the water permeability of cells by inserting aquaporin-2 in the cells of the last part of the DCT and CD; helps the body conserve water, and controls whether the urine is diluted or concentrated
dilute urine
ADH is low or absent, leading to decreased water reabsorption
concentrated urine
ADH is in higher levels, leading to increased water reabsorption
osmotic gradient
the difference in solute concentration between the outer renal cortex and inner medulla
countercurrent multiplier
the osmotic gradient in the renal medulla that is responsible for the concentration of urine
countercurrent exchange
process by which solutes and water are passively transported between the blood of the vasa recta and the interstitial fluid of the renal medulla
diuretics
drugs that cause the body to rid itself of excess fluids and sodium through urination; used to treat high blood pressure, congestive heart failure, and some congenital heart defects
urinalysis
evaluates for the presence of abnormalities in the urine
albuminuria
presence of protein in the urine; may indicate increased blood pressure or a kidney infection
hematuria
presence of blood in the urine; may indicate the presence of kidney stones, tumors, trauma, kidney disease
ketonuria
presence of ketone bodies in the urine; may indicate diabetes mellitus, anorexia, starvation, or a low-carb diet
bilirubinuria
the presence of bilirubin in the urine
urobilinogenuria
the presence of the breakdown product of hemoglobin in the urine; may indicate anemia, hepatitis, cirrhosis, or congestive heart failure
casts
tiny masses of material that have hardened and assumed the shape of the lumen in the part of the nephron in which they formed
blood urea nitrogen
measures blood nitrogen that is part of the urea resulting from the catabolism and deamination of amino acids
plasma creatinine
results from the catabolism of creatine phosphate in skeletal muscle; a measure of renal function
renal plasma clearance
the volume of blood cleared of a substance per unit time
acute renal failure
an abrupt decrease or complete cessation of glomerular filtration (over hours or days)
chronic renal failure
a progressive and often irreversible decline in the rate of glomerular filtration (over months or years)
hemodialysis
using artificial devices, like an artificial kidney machine, to cleanse the blood of wastes and excess fluid