Urinary System Flashcards
What are the main organs of the urinary system?
Kidneys
Ureters
Urinary bladder
Urethra
What are the functions of the urinary system?
- Excretion: removal of organic wastes from body fluids
- Elimination: discharge of waste products
- Homeostatic regulation: of blood plasma volume and solute concentration
Describe the location and shape of the kidney.
Location:
retroperitoneal, in the superior lumbar region (approximately from T12-L3)
right kidney is lower than the left, due to size of the liver
adrenal glands sit atop the kidney
Location: convex lateral surface, concave medial surface
renal hilum (notched area) leads to the renal sinus
Ureters, renal blood vessels, lymphatics, and nerves enter and exit at the hilum
Describe the supportive tissues around the kidney. What are they used for?
The supportive tissue is for protection for the kidney
- Renal fascia
- the anchoring outer layer of dens fibrous connective tissue - Perinephretic (perirenal) fat capsule
- a fatty cushion - Fibrous renal capsule
- prevents spread of infection to kid
Describe the internal anatomy of the kidney.
Renal cortex - granular superficial region
Renal medulla - deep to cortex, darker in color
lobe - a medullary pyramid and its surrounding corticol tissue
papilla- tip of pyramid, release urine into minor calyx
renal pelvis - the funnel-shaped tube with the renal sinus
major calyces - the branching channels of the renal pelvis that collect urine from minor calyces and empty urine into the pelvis
What is the path of blood flow through the kidney?
Renal artery > segmental arteries > interlobar arteries > arcuate arteries > cortical radiate arteries > afferent arterioles > (NEPHRONS) glomerulus > efferent arteriole > pertibular capillaries (nephrons) > venules > cortical radiate veins > arcuate veins > interlobar veins > renal vein
What are the two main parts of the nephron?
- Glomerulus - a tuft of capillaries, brings blood to be cleaned into the nephron
- Renal Tubule - area where the most of the urine product is fine tuned
What are the parts of a renal tubule?
Glomerular (Bowman’s) Capsule
Proximal Convoluted Tubule
Nephron Loop (Loop of Henle)
descending limb
ascending limb
Distal Convoluted Tubule
What are the three steps in urine formation?
- Glomerular filtration
- Tubular reabsorption
returns all glucose and amino acids, 99% of water, salt, and other components to the blood - Tubular secretion
Reverse of reabsorption; selective addition to urine
Describe the structural renal corpuscle. How does blood enter and leave the glomerulus? Describe the function of renal corpuscle.
Structure = Glomerulus + Bowman’s Capsule
Blood enters the glomerulus via the afferent arteriole and exits the glomerulus via the efferent arteriole
Function: filtration - high blood pressure in the glomerulus pushes small solutes and water out of the bloodstream and throught the filtration membrane into the Bowman’s capsule of the renal tubule.
What factors can influence of the GFR?
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Describe the structure of the Glomerular (Bowmans) Capsule?
1st portion of the renal tubule
cup-shaped and surrounds glomerulus
walls of the glomerular capsule are composed of cells called podocytes
podocytes contain feet like processes called pedicels
spaces between pedicels of podocytes are called filtration slits
Describe the structure of the Proximal Convoluted Tubule. Describe the function of the PCT.
structure: simple cuboidal epithelium
receives tubular fluid (filtrate) from Bowman’s Capsule
Function:
Reabsorption - main function
60-70% filtrate is reabsorbed back into the bloodstream
Secretion - secondary function
In secretion, PCT is secreting ammonium ions, creatinine, drugs, and toxins
Describe the structure of the Nephron Loop (Loop of Henle). Describe the functions of the Loop of Henle.
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Describe the structure of the Distal Convoluted Tubule. Describe the functions of the DCT.
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Describe the structure of the Collecting Systen, Describe the functions of the collecting system.
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How do the hormones Aldosterone, ADH, and ANP affect urine formation?
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What is the function of the Juxtaglomerular Apparatus - JGA? What are the main structures and cells involved in JGA?
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Describe the Renin-Angiotensin Mechanism
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Describe the location, structure, function of the ureters
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Describe the location, structure, and function of the bladder
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Describe the location, structure, and function of the urethra
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What are the differences between a male and female urethra?
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Describe.. color transparency odor pH specific gravity composition of urine
How much is normally produced per day?
clear, pale to deep yellow (due to urochrome)- color can be altered by drugs, vitamin supplements, and diet
cloudy urine may indicate a UTI
slightly aromatic when fresh, develops ammonia odor, may be altered by some drugs and vegetables
pH: slightly acidic (~pH 6, range of 4.5-8.0); diet prolonged vomiting, or UTI may alter pH
Specific gravity 1.001 to 1.035 dependent on solute concentration
95% water & 5% solutes
Nitrogenous wastes: urea, uric acid, and creatinine
Na+, K+, PO43-, and SO42-
Ca2+, Mg2+, and HCO3-
What would be some substances not normally found in urine. What pathologies could some of them indicate if they are present in the urine?
RBC WBC Bacteria Glucose Large proteins
Where are the micturition centers in the brain located?
Pontine (pons) control centers and corticospinal mature between ages 2 and 3 for conscious control over micturition
Describe the process of micturition in an adult
- ureters drip urine into bladder
- bladder fills to 200mL, stretch receptors send messages to spinal cord
- spinal cords parasympathetic messages back to the bladder
- 5.
6.
7.
8.
Describe the following urinary pathologies:
renal calculi
aka Nephrolithiasis
kidney stones form in renal pelvis
usually composed of crystallized calcium, magnesium, or uric acid salts
Larger stones block ureter, cause pressure and pain in kidneys
Maybe because of chronic bacterial infections, urine retention, increased calcium in blood. increased pH of urine
more common in males than females
riskier as we age
Describe the following urinary pathologies:
urinary tract infection
Usually caused by E. Coli (bacteria found in colon)
In UTI, bacteria get deposited in the urethra or bladder and can cause an infection
Symptoms: painful, frequent, sometimes blood-tinged urination = Dysuria
More commonly seen in females due to the location and length of the female urethra
Describe the following urinary pathologies:
renal failure
nickname?
definition?
possible causes?
Treatments?
aka: kidney failure
when the number of functioning nephrons becomes too low to carry out normal kidney functions
because of kidney failure, toxic wastes will quickly accumulate in the blood
Possibles causes: repeated infections damaging the kidneys physical trauma to kidneys chemical poisoning of kidneys inadequate blood supply to the kidneys
Treatments:
Dialysis - artificial means to clean the blood
must undergo 4-8 hours/3days a week
Kidney Transplant
Describe the following urinary pathologies:
glomerulonephritis
inflammation of the glomerulus of kidney, which disrupts proper filtration
can be the result of a Streprococcus infection. Usually infection is not in kidney, but antigen-antibody produce the immune system clog the filtration mechnism in the glomerulus as they circulate in the blood. This decreases the GFR.
Dysuria
another name for painful urination
Urethritis
infection in urethra
Cystitis
bladder infection
Pyelonephritis
kidney infection
Micturition
Urination or voiding
Incontinence
inability to control urination voluntarily
What are the 3 simultaneous events of micturition
- Contraction of detrusor muscle by ANS
- Opening of internal urethral sphincter by ANS
- Opening of external urethral sphincter by somatic nervous system
Urinary tract
Organs that eliminate urine
Distal Convoluted Tubule
Receives the remaining tubular fluid from the ascending limb of the Loop of Henle
Main function is secretion
Macula densa cells located here
Nephron Loop /Loop of Henle
Will extend down into renal medulla of kidney
Filtrate flows from PCT into the descending limb, then into the ascending limb
Proximal Convoluted Tubule
Simple cuboidal epithelium
Receives tubular fluid from Bowman’s capsule
Main function: reabsorption
Secondary function: secretion
Glomerular (Bowman’s) Capsule
1st portion of the renal tubule
Cup shaped and surround glomerulus
Walls contain cells: podocytes
Renal tubule
Where urine is fine tuned Has sections: Glomerular capsule Proximal convoluted tubule Nephron loop Distal convoluted tubule
Glomerulus
A tuft of capillaries
Brings blood to be cleaned into the nephron
Blood enters this via afferent arteriole, exits via efferent arteriole
Walls composed of Fenestrated glomerular endothelium
Renal pelvis
The funnel-shape tube within renal sinus
Papilla
Tip of pyramid, release urine into minor calyx
Fibrous renal capsule
Prevents spread of infection to kidney
Tissue layer outside of the kidney
Perinephretic (perirenal) fat capsule
A fatty cushion
Tissue layer outside of the kidney
Renal fascia
The anchoring layer of dense fibrous connective tissue supporting the outside of the kidney
Urinary bladder
Temporary storage for urine
Muscular sac
Ureters
Paired tubes
Transport urine from kidneys to the bladder
Kidneys
Organs that produce urine
Major excretory organ
Trigone
In urinary bladder
Smooth triangular area outlined by the opening for ureters and urethra
Acts as a funnel to channel urine towards the urethra
Renal cortex
granular superficial region, lighter color (kidney)
Renal medulla
deep to cortex and darker in color
cone-shaped medullary renal pyramids separated by renal columns (kidney)
Major calyx
The branching channels of the renal pelvis that collect urine from minor calyces and empty urine into the pelvis
Minor calyx
Receives urine from papilla
Urine
Excess water of nutrients, toxins that the body does not need
Urine is sterile, see other notecard
Nephron
Structural and functional units that form urine
the “filters” of the kidney
~1 million per kidney, microscopic
Takes blood filters out toxins, excess water/nutrients body does not need
Nephron returns filtered blood back to the body
Pertibular capillaries
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Vasa recta
the name of the blood vessel that surrounds the loop of Henle and reabsorbs ions and water back into the bloodstream
Renal corpuscle
Glomerulus + it Glomerular (Bowman’s) Capsule
Podocytes
Cells in the walls of Bowman’s capsule
Pedicels
“feet-like” processes in podocytes
Filtration slits
Spaces between pedicels of podocytes
filtrate
fluid found inside the nephron, this is what will become urine
Tubular fluid
aka filtrate
fluid found inside the nephron
Glomerular Filtration Rate = GFR
The rate of filtrate production per minute
GFR is ~125mL/min
Detrusor muscle
three layers of smooth muscle in the urinary bladder
diuretics
substances that increase the amount of urine output
Example: osmotic diuretics, ADH inhibitors, caffeine, other drugs
Granular cells
aka Juxtaglomerular or JG cells
Main cells in JGA
Enlarged smooth muscle cells of arteriole
Secretory granules contain the hormone renin
Act as a mechanoreceptors that sense blood pressure, stimulated when pressure of blood drops
Macula densa
Tall closely packed cells of the ascending limb of the nephron loop
Detect if the filtration rate has dropped
Descending limb
Made up of simple squamous epithelial cells, which are permeable to water, but do not contain pumps or transport proteins for solutes, water will be reabsorbed here
Ascending limb
Composed of cuboidal epithelial cells covered with glycoprotein layer
Less permeable to water, but more able to pump solutes and ions
Sodium and chloride will be reabsorbed here
Countercurrent multiplication
the movement of fluid back and forth between the ascending and descending limb of the loop
Helps drive the movement of water, sodium ions, and chloride ions in the DCT
Collecting Ducts
Receive filtrate from the DCT of many nephrons out in the cortex of the kidney
Larger than tubules in the nephron because they collect fluid from many nephrons
Empty their filtrate into larger papillary ducts influenced by Aldosterone and ADH
Inner mucosa layer
lining of transitional epithelium with mucous of the ureter wall
middle mucosa layer
smooth muscle muscularis of the ureter wall
contracts in response to stretch
can perform peristaltic waves to propel urine
Outer connective tissue layer
Adventitia of fibrous connective tissue of the ureter wall
Inner layer of urethra
mostly pseudostratified columnar epithelium
What are the
Five Homeostatic Functions of the Urinary System
- Regulates blood volume and blood pressure:
- adjusts volume of water lost in urine
- releasing erythropoietin and renin - Regulates plasma ion concentrations
- Helps stabilize blood pH:
- by controlling loss of hydrogen ions and bicarbonate ions in urine - Conserves valuable nutrients
- by preventing excretion while excreting organic waste products - Assists liver in detoxifying poisons
