M5 U2 Urinary System Flashcards
URINARY SYSTEM Consists of
two kidneys
two ureters
one urinary bladder
one urethra.
principal organs of the urinary system
kidneys
kidneys process and form ___ as a waste to be excreted.
urine
what kidney is often slightly larger than
the other
left kidney
The medial surface of each kidney has a concave notch called___
Structures enter or leave the kidney through this notch.
hilum.
connective tissue that anchors the
kidneys to surrounding structures and also helps maintain their normal positions
renal fasciae
outer region
Renal cortex
inner region
Renal medulla
important functions of kidney
filtering the plasma
removing substances from the filtrate at variable rates
critical in controlling the volume and composition of the body fluids.
kidneys
the primary means for eliminating
waste products of metabolism that are no longer needed by the body.
kidneys
(from the metabolism of amino acids)
urea
(from muscle creatine)
creatinine
(from nucleic acids)
uric acid
Responsible for regulation of long-term arterial pressure by excreting variable amounts of
sodium and water.
KIDNEYS
Responsible for short-term arterial pressure regulation by secreting renin (Renin-Angiotensin-aldosterone system, RAAS).
KIDNEYS
contribute to acid-base regulation, along with the lungs, by excreting acids and by regulating the body fluid buffer stores.
KIDNEYS
only means of eliminating from the body certain types of acids, such as sulfuric acid and
phosphoric acid, generated by the metabolism of proteins.
KIDNEYS
Kidneys secrete ____ (along with the liver), which stimulates the production of red blood cells by hematopoietic stem cells in the bone marrow
erythropoietin
develops as a result of decreased erythropoietin
production.
severe anemia
essential for normal calcium deposition
in bone and calcium reabsorption by the
gastrointestinal tract.
Calcitriol
The kidneys synthesize glucose from amino acids and other precursors during prolonged fasting, a process referred to as
gluconeogenesis.
enough potassium, acids,
fluid, and other substances accumulate in the body to cause death within a few days,
complete renal failure
homeostatic functions are disrupted and
severe abnormalities of body fluid volumes and
composition rapidly occur.
kidney disease or acute failure of the kidneys
functional unit of the kidney.
NEPHRON
Each kidney in the human contains about ___ to __ nephrons
800,000 to 1,000,000 nephrons,
nephron consists of two parts:
Renal corpuscle
Renal tubule
where blood plasma is filtered
Renal corpuscle
Where the glomerular filtrate (filtered
fluid) passes
Renal tubule
Nephrons whose glomeruli lie in the renal cortex and have short Loops of Henle that penetrate a short distance in the medulla
Cortical nephrons
-20-30%
-Nephrons whose glomeruli lie near the renal medulla, and have long Loops of Henle that dip deeply into the medulla.
Juxtamedullary nephron
renal processes:
Glomerular filtration
Reabsorption of substances from the renal tubules into the blood
Secretion of substances from the blood into the renal tubules
The fluid that enters the capsular space is
called the
glomerular filtrate
Blood pressure in glomerular capillaries
promotes filtration by forcing water and solutes in blood plasma through the filtration membrane
55 mmHg
Glomerular blood hydrostatic pressure (GBHP)
hydrostatic pressure exerted against the filtration membrane by fluid already in the capsular space and renal tubule
CHP opposes filtration and represents a “back pressure” of about 15 mmHg
Capsular hydrostatic pressure (CHP)
due to the presence of proteins such as albumin, globulins, and fibrinogen in blood plasma, also opposes filtration
30 mmHg
Blood colloid osmotic pressure (BCOP)
occurs to Waste products such as Creatinine
Substance is freely filtered but not reabsorbed
Typical for electrolytes such as sodium and chloride
The substance is freely filtered, but part of the
filtered load is reabsorbed back in the blood
occurs to Nutritional substances in the blood, such as amino acids
and glucose
The substance is freely filtered but is not excreted in the urine because all the filtered
substance is reabsorbed from the tubules into
the blood
Often occurs for organic acids and bases
The substance is freely filtered and is not reabsorbed but is secreted from the peritubular
capillary blood into the renal tubules.
successive parts of the tubule before it is excreted as urine:
proximal convoluted tubule
the loop of Henle
the distal convoluted tubule
the collecting tubule
the collecting duct
The largest amount of solute and water
reabsorption from filtered fluid occurs in
the proximal convoluted tubules
Proximal convoluted tubule
Proximal convoluted tubule reabsorbs
65% of the filtered water, Na+ and K+
100% of organic solutes such as glucose and
amino acids
50% of the filtered Cl-, urea
80-90% of the filtered Ca2+, Mg2+, and
HPO42−
Proximal convoluted tubule secretes
H+
NH4+
Urea and creatinine
Consists of an descending limb, thin ascending
limb, and thick ascending limb
Loop of Henle
The nephron loop reabsorbs:
- Descending limb:
15% of the filtered water - Ascending limb
20-30% of the filtered Na+ and K+
35% of the filtered Cl-
10-20% HCO3-
Ca+ and Mg+
The early distal convoluted tubule reabsorbs:
10-15% of the filtered water
5% of the filtered Na+ and 5% Cl-
A major site for parathyroid hormone to
stimulate reabsorption of Ca2+.
Early distal convoluted tubule
group of closely packed
epithelial cells that is part of the
juxtaglomerular apparatus and provides
feedback control of GFR and blood flow in
this same nephron.
macula densa
the amount of water and
solute reabsorption and the amount of solute
secretion vary depending on the body’s
needs in the
the late distal convoluted tubules
collecting ducts
reabsorb Na+ and secrete
K+. These cells also have receptors for
aldosterone and antidiuretic hormone (ADH).
principal cells
reabsorb HCO3− and secrete H+, thereby playing a role in blood pH regulation. In addition, the intercalated cells reabsorb K+.
intercalated cells
Found at the point where the afferent arteriole
brushes past the distal tubule
This structure is important in maintaining
homeostasis of blood flow because it
reflexively secretes renin when blood pressure
in the afferent arteriole drops
JUXTAGLOMERULAR APPARATUS
Mechanoreceptors
Sensitive to increased pressure in the arteriole
Juxtaglomerular cells
Tightly-packed structure made up of distal
tubule cells that act as Chemoreceptors
Can sense the concentration of solute materials
in the fluid passing through the tubule
Macula densa
A straight tubule joined by the distal tubules
of several nephrons
COLLECTING DUCT
reabsorbs water
through osmosis only in the presence of ADH
COLLECTING DUCT
Tubes that actively convey urine from the
kidneys to the urinary bladder
URETERS
Runs obliquely through the bladder wall and
opens at lateral angles. Because of its oblique
course, the ends of the tubes close, acting as
valves when the bladder is full, thus
preventing backflow of urine
URETERS
A muscular, collapsible bag
URINARY BLADDER
The wall of the bladder is made mostly of
smooth muscle tissue, called the
detrusor
muscle
the bladder is lined with
mucous transitional epithelium that forms rugae
allows the bladder to distend considerably.
rugae,
Serves as a reservoir for urine before it leaves
the body
URINARY BLADDER
The mechanism for voiding urine begins with
the voluntary relaxation of the external
sphincter muscle of the bladder
MICTURITION
This forces urine out of
MICTURITION
Involuntary micturition is called
incontinence
small tube lined with mucous membrane leading from the floor of the bladder
(trigone) to the exterior of the body
urethra
passes through the center of the prostate gland, just after leaving the
bladder.
male urethra
