URINARY SYSTEM Flashcards
major excretory system of the body
urinary system
what are the primary excretory organs in the urinary system
two kidneys
urine consists of
excess water
excess iones
metabolic wastes, including urea (by product of protein)
toxic substances
functions of kidneys
excretion
regulation of blood volume and pressure
regulation of blood solute concentrations
regulation of red blood cells synthesis
regulation of vitamin D synthesis
kidneys secrete a hormone which regulates the synthesis of red blood cells in bone marrow
erythropoietin
the kidneys are behind the peritoneum or
retroperitoneal
bean shaped organs, each about the size of a tightly clenched fist
kidney
a layer of connective tissue called the _ _ surrounds each kidney
renal capsule
on the medial side of each kidney is the _, where the renal artery and nerves enter and where the renal vein, ureter, and lymphatic vessels exit the kidneys
hilum
the hilum opens into a cavity called _ _ which contains blood vessels, part of the system for collecting urine and adipose tissue
renal sinus
two major regions of the kidney
cortex (outer)
medulla (inner)
location for blood filtering structure of the kidney
cortex
the medulla is composed of many cone-shaped structures called the _ whose bases project int the cortex
renal pyramids
a collection of tubes and ducts that transport fluid throughout the kidney and modify it into urine
renal pyramids
the tips of the pyramids called the _ _ point toward the renal sinus
renal papillae
when urine leaves a renal papilla, it empties into a small, funnel-shaped chamber surrounding the tip of the papilla called the _
calyx
urine from several calyces is emptied into a single, enlarged, funnel-shaped chamber called the _
renal pelvis
small diameter tube called the _
ureter
the histological and functional unit of the kidney
nephron
it consists of specialized structure including small tubes called
tubules
the four regions of a nephron are
renal corpuscle
proximal convoluted tubule
loop of henle
distal convoluted tubule
region that filters the blood
renal corpuscle
region that returns filtered substances to the blood
proximal convoluted tubule
region that helps conserve water and solutes
loop of henle
region that rids the blood of additional wastes
distal convoluted tubule
several connecting ducts merge int a large-diameter tubule called a _ which empties into a calyx
papillary duct
two types of nephrons
juxtamedullary nephrons
cortical nephrons
have renal corpuscles that are found deep in the cortex near the medulla
juxtamedullary nephrons
have renal corpuscles that are distributed throughout the cortex
cortical nephrons
the loops of henle of cortical nephrons are _ than those of juxtamedullary nephrons
shorter
the loops of juxtamedullary nephrons are
long (extend deep into the medulla) ; well adapted for water conservation
the filtration portion of the nephron is housed in the
renal corpuscle
the renal corpuscle consists of (2):
glomerulus
bowman capsule or glomerular capsule
a network of capillaries twisted around each other like a ball of yarn
glomerulus
an indented, double-walled chamber surrounding the glomerulus
bowman capsule or glomerular capsule
bowman capsule consists of two layers
inner
outer
constructed of simple squamous epithelial cells
outer layer
constructed of specialized cels called podocytes which wrap around the glomerular capillaries
inner layer
supplies blood to the glomerulus for filtration
afferent arteriole
transports filtered blood away from the glomerulus
efferent arteriole
the structures in the corpuscle make up the _ ; consists of capillary endothelium, the basement membrane, and the podocytes of the bowman capsule
filtration membrane
an important regulatory structure called the _ is located next to the glomerulus
juxtaglomerular apparatus
at the point where the affarent arteriole enters the renal corpuscle, it has a cuff of specialized smooth muscle cells around it. these cells are called
juxtaglomerular cells
a part of the distal convoluted tubule of the nephron lies between the afferent and efferent arterioles next to the renal corpuscle. in this section of the distal convoluted tubule, there is a group of specialized cells called the
macula densa
once the blood is filtered, the resulting fluid is modified to form urine as it passes through each section of the renal tubule. the first section is the
proximal convoluted tubule
as the proximal convoluted tubule continues descending toward the medulla, the cell type begins to change. the renal tubule is now called _
loop henle
every loop of henle has two limbs:
descending limb
ascending limb
is shorter than the proximal convoluted tubule. its epithelium is simple cuboidal
distal convoluted tubule
several distal convoluted tubules connect to a single _ which is composed of simple cuboidal epithelium
collecting duct
branch off the abdominal aorta and enter the kidneys
renal arteries
list of blood vessels in order
interlobar arteries
arcuate arteries
interlobular arteries
afferent arterioles
efferent arterioles
peritubular capillaries
pass between the renal pyramids
interlobar arteries
branch from the interlobal arteries ; they arch between the cortex and the medulla
arcuate arteries
branch off the arcuate arteries and project into the cortex
interlobular arterioles
carry blood from the glomerular capillaries
efferent arterioles
arise from the branches of the interlobular arteries ; the afferent arterioles carry blood to the glomerular capillaries
afferent arterioles
branch from different efferent arterioles ; they surround the proximal convoluted tubules, the distal convoluted tubules, and the loops of henle
peritubular capillaries
are specialized portions of the peritubular capillaries that extend deep into the medulla of the kidney and surrounds the loops of henle and collecting ducts
vasa recta
categories of urine formation (3):
filtration
tubular reabsorption
tubular secretion
a non specific process whereby materials are separated based on size or change
filtration
an average of _ of the blood pumped by the heart each minute flows through the kidneys
21%
in the nephrons, about 180 liters of filtrate is produced each day , but only about _ or less becomes urine
1%
the renal corpuscles in the renal cortex contain filtration structures each of which is called a _
filtration membrane
the combination of three pressures is called a
filtration pressure
causes constriction of the kidney arteries
sympathetic stimulation
intense sympathetic stimulation may significantly decrease filtrate formation and urine volume by
circulatory shock or vigorous exercise
decreased sympathetic formation of renal blood arteries _ renal blood flow and urine volume
increases
is the transport of water and solutes from the filtrate into the blood
tubular reabsorption
site of the majority of reabsorption
proximal convoluted tubule
the movement of non filtered substances from the blood into the filtrate
tubular secretion
the kidneys are able to produce very dilute or concentrated urine while maintaining the extracellular fluid concentration very close to _msm/L
300
the kidneys’ ability to control the volume and concentration of the urine depends on three factors
countercurrent mechanisms
medullary concentration gradient
hormonal mechanisms
is one where fluid in separate structures flows in the opposite directions relative to each other
countercurrent mechanism
maintains the high solute concentration in the interstitial fluid
vasa recta
the interstitial fluid in the medulla of the kidney has a very high solute concentration compared with that of the cortex. this is called the
medullary concentration gradient
the concentration of solute in the medulla increases from 300 to _
1200
as filtrate travels through the descending limb of the loop of henle, water moves across its simple squamous epithelium by osmosis toward the higher solute concentration in the interstitial fluid
countercurrent mechanism
urea is responsible for a substantial part of the high solute concentration in the kidney medulla
urea cycling
three major hormonal mechanisms are involved in regulating the urine concentration and volume
renin-angiostensin-aldosterone (sensitive to changes in blood pressure)
antidiueretic hormone (ADH) mechanism (sensitive to changes in blood concentration)
atrial natriuretic hormone (ANH) mechanism (sensitive to changes in blood pressure)
initiated under low blood pressure conditions
renin-angiostensin-aldosterone
when blood pressure decrease, cells of juxtaglomerular apparatuses in the kidneys secrete the enzyme
renin
upon secretion, renin enters the blood and converts angiotensinogen, a plasma protein, to
angiostensin I.
enzyme produced by capillaries or organs such as the lungs
Angiostensin-covering enzyme (ACE)
Angiostensin-covering enzyme (ACE) converts angiostensin I to
angiostensin II
increases blood pressure and increases sensation of thirst, and salt appetite ; stimulates the adrenal cortex to secrete aldosterone
angiostensin II
is secreted by neurons in the posterior pituitary when the solute concentration of the blood or the interstitial fluid increase
antidiuretic hormone (ADH)
promotes water conservation in the kidneys by increasing the permeability of the distal convoluted tubules and collecting ducts of water
antidiuretic hormone (ADH)
a low blood solute concentration inhibits ADH secretion which
reduces urine volume
decrease in blood pressure causes ADH to
increase
when blood pressure increases, ADH secretion
decreases
ADH is more sensitive to changes in _ _ than to blood pressure
blood osmolarity
an increased blood pressure triggers the
atrial natriuretic hormone (ANH) mechanism
