Urinary Flashcards
The urinary consists of 4 parts of the body. What are the 4 parts and what are each of their functions?
- Kidneys - Form Urine
- Ureters - Transport Urine
- Urinary Bladder - Store Urine
- Urethra - Carries Urine to Outside of Body
What are some of the major functions and characteristics of the kidneys? (There are 4 of them)
- Regulates composition of body fluids (i.e., water balance)
- Rids body of wastes of metabolism
- Removes foreign chemicals, drugs and food additives
- Minor endocrine organs (i.e., renin-angiotensin system and erythropoietin)
Where are the kidneys located in the body?
Either side of vertebral column in abdominal cavity between 12th and 3rd lumbar vertebrae.
What is the outer portion of the kidney called and what does it contain?
- Renal Cortex
2. Contains capillary tufts and convoluted tubules
What is the inner portion of the kidney called and what is it composed of?
Renal Medulla
Composed of a series of triangular masses (renal pyramids) which are separated by renal columns.
What are the symptoms of acute renal failure?
A sudden loss of kidney function, usually associated with shock or intence renal vasoconstriction. It can last for several days to a long as weeks
What is cystitis?
Inflammation of the urinary bladder
What is hemoturia?
Blood in the urine
What is Hemodialysis?
It is a method of clearing waste products from the blood in which blood passes by the semipermeable membrance of the artificial kidney and waste products are removed by diffusion
What is nocturia?
“night urination” or during sleep
What is oliguria?
the condition of having urinary volumes of less than 500 ml/day
What is plyuria?
Excessive urine output
What is uremia?
The retention of urinary constituents in the blood, owing to kidney dysfunction
What are the six parts of the nephron?
The Glomerulus Bowman's Capsule (glomerular capsule) Proximal Convoluted Tubule Loop of Henle (Nephron Loop) Distal Convoluted Tubule Collecting Duct
About how many nephrons are there per kidney?
Over 1 million
True or false: One collecting duct can serve several nephrons
TRUE
Describe the make-up a the glomerulus
A network of 50 capillaries with many circular fenestrations (pores)
Why is the glomerulus more permeable than typical capillaries and by how much?
The pores have a diameter of 50-100 nm.
100-1000 times more permeable
Describe the Bowman’s capsule (glomerular capsule)
It is a double-walled cuplike structure composed of squamous epithilium.
What is the difference between the inner and out layers of epithelium in the glomeruluar capsule?
The outer layer is continuous with the epithelium of the proximal tubule whereas the innter layer is composed of modified cells called podocytes that are closely associated with the glomerular capillaries
What is unique about the proximal convoluted tubule?
It is continuous with the epithelium of the glomerular capsule and consists of a single layer of cuboidal cells containing microvilli to greatly increase the surface are
What the nephron loop composed of?
A descending and ascending thin limb and an ascending thick portion.
The thin segments are lined with flat squamous cells without microvilli
The cubodial cells in the thick segment also lack microvilli
Where is the thick segment of the nephron loop located?
It runs between the afferent and efferent arterioles
What is the macula densa?
A mass of specialized epithelial cells of the tubule wall located next to the afferent arteriole
True or false: The distal convoluted tubule is longer than the proximal convoluted tubule
FALSE- the distal convoluted tubule is shorter than the proximal convoluted tubule and contains fewer microvilli
Where is the distal convoluted tubule located?
It starts at the macula dens and terminates as it empties into the collecting duct.
It is the last segment of the nephron
Why does the proximal convoluted tubule have a lot of mitochondria?
Because is uses active transport which requires a lot of energy
What are the three major functions of the nephron?
1) Glomerular Filtraion
2) Tubular Reabsorption
3) Tubular Secretion
What is the portion of the blood plasma that enters the glomerular capsule?
Glomerular Filtrate
How much glomerular filtrate enters the glomerular capsule each day?
180 L (45 gallons)
What two mechanisms cause 180 L of fluid to be filtered each day in the glomerular capsule?
1) The high hydrostatic pressure of the blood (45 to 60 mmHg) in the glomerulus
2) The large numbers of pores, which are larger than most pores in blood capillaries
What substances in the blood are present in the glomerular filtrate?
Water, electrolytes, glucose, amino acids, urea, hormones, and vitamins
Why are RBC’s, WBC’s, and platlets excluded from passage in the glomerular filtrate?
Because of their large size
What does the presence of RBC’s or protein in the urine indicate?
It indicates that the hydrostatic pressure in the glomerular capillaries is excessively high or that there is a defect in the glomerular
What is the average glomerular filtration rate (GFR) per minute? Per hour? Per day?
120 ml per minute or
7.5 L per hour or
180 L per day
What two mechanisms regulate GFR via vasoconstriction or vasodilation?
Extrinsic (sympathetic nerves) and
Intrinsic (locally produced chemicals)
How do you measure GFR?
Multiply urine volume by inulin concentration in urine.
Then divide both by inulin concentration in plasma
What is inulin?
A polymer of fructose that is extracted from plants
What is tubular reabsorption?
The transfer of fluid and solutes out of the lumen of the nephron through the interstitial space and into the peritubular capillaries
In comparison to how much glomerular filtrate is produced, how much do the kidneys normally excrete?
180 L/day is produced
only 1 to 2 L of urine is excreted
How much filtrate is reabsorbed from the renal tubules?
99%
How is urine volume regulated?
According to the needs of the body