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URINARY SYSTEM
Bio 2402
100
Anatomy
04/26/2009

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Cards

Term
The urinary system consists of:
Definition
kidneys, ureters, urinary bladder, urethra
Term
What are the three primary functions of the urinary system?
Definition

excretion -

elimination -

homeostatic regulation of volume and solute concentration of blood plasma

Term
In the urinary system, explain "excretion"
Definition

The removal of organic waste products from body fluids

Term
In the urinary system, explain "elimination"
Definition

The discharge of waste products into the environment

Term
In the urinary system, explain the essential functions of "homeostatic regulation"
Definition

1. regulating blood volume and blood pressure - 2. regulating plasma concentrations -

3. helping stabilize blood pH -

4. conserving nutrients (while excreting organic wastes such as urea and urid acid)

Term
The urinary system eliminates dissolved organic waste products generated by how many cells in the human body?
Definition
75 TRILLION !!
Term
Urine is the end product of what organ?
Definition
The kidneys
Term
What is the end product of the kidneys?
Definition
Urine
Term
What are the basic functional units of the kidneys?
Definition
Nephron
Term
What is the structural make-up of a nephron?
Definition
A renal corpuscle, made of glomerulus within a cup-shaped Bowman's capsule
Term
What path does blood enter and exit the glomerulus?
Definition

Enters through the afferent arteriole -

 

Exits through the efferent arteriole

 

HINT: E for Exit

Term
The Bowman's capsule leads into the renal tubule divided into what three regions?
Definition

Proximal convoluted tubule -

 

Loop of Henle via descending limbs and ascending limbs -

 

distal convoluted tubule, which leads into the collecting ducts

Term
What are the steps in the function of the nephron?
Definition

1. blood brought in by afferent arteriole. Gets filtered in Bowman's capsule.

 

2. filtrate passes through different parts of renal tube

 

3. undergoes changes in composition (ions, water, organic nutrients)

 

4. waste, with very little nutrients and water empty into collecting duct.

Term
What is the specific function of the nephron?
Definition
TO CONVERT FILTRATE INTO URINE
Term
How does the nephron convert filtrate into urine?
Definition

1. Reabsorbs all useful nutrients -

 

2. Reabsorbs >90% of water -

 

3. Secretes any waste products into tubular fluid that missed the filtration process

Term
What percentage of blood from total cardiac output flows through the kidneys each minute?
Definition
20-25%
Term
What is GFR?
Definition
Glomerular filtration rate, which determines the amount of filtrate produced per minute
Term
How much filtrate, in a 24-hour period, does the glomerulus secrete?
Definition

50 gallons of filtrate, which is

 

70x the total plasma volume.

 

OVER 99% gets reabsorbed

Term
What is the sequence of filtration?
Definition

1. Blood flows into Bowman's capsule via afferent arteriole (where it gets filtered) . -

2. Filtered blood leaves Bowman's capsule via Efferent arteriole (remember: E for Exit) -

3. Within the proximal convoluted tubule (PCT) 60-70% of the water and >90% of the dissolved nutrients are REABSORBED. -

4. As filtrate descends the PCT into the Loop of Henle, more water gets reabsorbed, which leaves the residual filtrate highly concentrated.

5. The highly concentrated filtrate travels back up the LoH (ascending limb) toward the distal convoluted tubule (DCT). Water IS NOT recycled at this portion of the LoH. (Must have ADH at this point to reabsorb)

6. Within the DCT and collecting ducts, no more solutes are lost or reclaimed. (Note: Aldosterone can regulate active transport of ions in or out as needed)

NOTE: Aldosterone controls sodium absorption and potassium loss along DCT

7. Urine concentration as it reaches the renal pelvis varies. (Note: DCT and collecting ducts are impermeable to water unless regulated by antidiuretic hormone (ADH)

8. AT THE POINT OF entry into the collecting duct and renal pelvis, the FILTRATE HAS NOW BEEN CHANGED AND IS URINE

Term
Where is urine formed and how does it travel to elimination?
Definition
Urine is formed in the kidneys, travels through the ureter, into the bladder, through the urethra and out into the environment
Term
On average, how much urine collects in the bladder when the urge to urinate appears?
Definition
200 mL
Term
What is the maximum average amount of urine a bladder can hold?
Definition
500 mL
Term
How long can a person not urinate before death occurs?
Definition
36 hours
Term
What is the affect of not urinating for 36 hours?
Definition
death
Term
After urination, what is the normal average of urine remaining in the bladder?
Definition
<10 mL
Term
What function moves urine from the ureters to the urinary bladder?
Definition
peristalic contractions
Term
The process of urination is coordinated by what reflex?
Definition
micturition reflex (which signals the stretch receptors)
Term
What muscles contract the urinary bladder to force urine out into the urethra?
Definition
detrusor muscles
Term
As the urinary bladder fills with urine, what sensory receptors are activated, signaling the urge to urinate?
Definition
stretch receptors
Term
A full bladder can hold up to how much urine?
Definition
500 mL
Term
How often do peristalic contractions begin within the kidney to move urine from the ureter to the bladder?
Definition
every 30 seconds
Term
Where is urine stored prior to urination?
Definition
in the bladder
Term
What are three of the waste products excreted by the urine?
Definition

urea -

uric acid -

creatinine

Term
What is the basic process of urine formation?
Definition

1. Filtration -

2. Reabsorption -

3. Secretion -

Term
How much blood is filtered through the kidneys every minute?
Definition
1.2 quarts, which is 25% of the blood pumped by heart
Term
Where are the kidneys located in the body?
Definition
retroperitoneal (behind the peritoneal cavity). On either side of the veterbral column, between T12 and L3. The left kidney is slightly superior to the right kidney
Term
Name the blood supply to the kidney
Definition
renal, segmental, interlobar, arcuate, corticol radiate arteries (interlobular)
Term
Each kidney weighs approximately how much?
Definition
5.25 ounces
Term
What is urinalysis?
Definition
The chemical and physical analysis of urine
Term
What causes variation of composition of urine produced each day?
Definition
metabolic and hormonal events of the body
Term
The COMPOSITION of normal urine reflects what nephron activities?
Definition
filtration, absorption, secretion
Term
How many LITERS of filtrate are produced each day by the glomerulus? How much is reabsorbed?
Definition
180 liters of filtrate is produced each day by the glomerulus. More than 99% is reabsorbed.
Term
Once the bladder contains about 200mL of urine, which reflex signals the stretch receptors
Definition
Micturition reflex, which signals the stretch receptors, stimulating the need to urinate
Term
At what range of volume will urination occur despite voluntary opposition?
Definition
500 mL
Term
What is incontinence?
Definition
a condition characterized by the lack of voluntary control over urination
Term
In the urination system, what age-related changes start taking place?
Definition

Decline in the number of functional nephrons -

 

reduction of GFR (glomerular filtration rate) -

 

reduced sensitivity to ADH

 

problems with micturition reflex

Term
What is metabolism?
Definition
chemical reactions that occur in the body
Term
What balances within the body are essential to homeostasis?
Definition
fluid balance, electrolyte balance, acid-based balance
Term
What does pH mean?
Definition

hydrogen ion concentration

 

Remember: The power of Hydrogen

Term
Which system in the body is the primary source for electrolyte balance?
Definition
digestive system
Term
Which system in the body is the primary source for electrolyte loss?
Definition
Urinary system
Term
What is extracellular fluid comprised of?
Definition
interstitial fluid, plasma and other body fluids
Term
What percentage of ECF is water?
Definition
99%
Term
The body is in "fluid balance" when...
Definition
the amount of water gained each day is equal to the amount lost
Term
You are in "electrolyte balance" when...
Definition
the amount of ions gained each day is equal to the amount of ions lost each day
Term
You are in "acid-based balance" when...
Definition
the production of hydrogen ions is offset by their loss.
Term
When the body is in acid-base balance, what will the pH range be in?
Definition
Within normal limits
Term
At what percent of dehydration is the body alerted to being thirsty?
Definition
10% dehydration
Term
ECF and ICF are classified as how many compartments?
Definition
ECF and ICF are two distinct compartments
Term
As a diffusion medium for distribution of ions, nutrients and waste products, what does the operation of all cells rely on?
Definition
water
Term
Regarding cell operation, why is it necessary that water content be tightly monitored and regulated?
Definition
Because water is the diffusion medium for the distribution of ions, nutrients and waste products of cells
Term
An average body contains how many liters of water?
Definition
36
Term
Water accounts for what percentage in an adult male and what percentage in an adult female?
Definition
Male = 60% water - Female = 50% water
Term
In the adult male, what percentage is water and what percentage is protein/lipids?
Definition
Male = 60% water, 40% proteins, lipids
Term
In the adult female, what percentage is water and what percentage is protein/lipids?
Definition
Female = 50% water, 50% proteins/lipids
Term
Primary regulatory hormones in the body are:
Definition

Antidiuretic hormone (ADH), which stimulates water conservation and the thirst center - this will raise blood volume and blood pressure

 

Aldosterone, which controls Na+ absorption and K+ loss along the DCT, -

 

Natriuretic peptides (ANP and BNP), which reduce thirst and block release of ADH and aldosterone - this will promote fluid loss and lower blood volume and blood pressure

Term
Fluid moves freely within which fluid compartment?
Definition
Extracellular fluid compartment (ECF)
Term
What are the major routes of fluid exchange with the environment?
Definition
water loss, water gains, temperature rise from fever
Term
Sodium (Na+)balance - rate of sodium uptake across the digestive tract is directly proportional to what?
Definition
dietary intake
Term
How is Na+ lost to the environment?
Definition
Through urine and perspiration
Term
If sodium balance is too low, what two hormones are secreted to get back in homeostasis?
Definition
Sodium too low = secretion of ADH and Aldosterone
Term
If sodium imbalance is too high, what hormone is secreted to get back in homeostasis?
Definition
The natriuretic peptide, ANP which reduces thirst and blocks the release of ADH and Aldosterone
Term
If blood pressure is too low, what hormones are released?
Definition
ADH and Aldosterone, which stimulate water conservation and the thirst center which promotes the intake of water. This will help (build) raise the blood volume, thus raise blood pressure
Term
If blood pressure is too high, what hormone is released and why?
Definition
Natriuretic peptides ANP and BNP, which reduce thirst and water conservation. The resulting diuresis will result in fluid loss at kidneys, thus lowering blood volume and blood pressure.
Term
What two "pressures" regulate the movement of water and electrolytes to maintain fluid balance?
Definition
osmotic pressure and hydrostatic pressure
Term
glomelular filtration produces filtrate with a composition similar to what? What is the compositional difference?
Definition
filtrate produced by GF is similar to blood plasma, but with no proteins
Term
Most regions of the nephron perform a combination of what two functions?
Definition
reabsorption and secretion
Term
Most water reabsorption takes place along what region of the nephron?
Definition
PCT - proximal convoluted tubule
Term
Why doesn't water reabsorb at the distal convoluted tubule without aid of a specific hormone? What is that hormone?
Definition
The DCT is not permeable to water. The hormone needed for reabsorption at this point is ADH
Term
Shifts in sodium balance result in expansion or contraction of what?
Definition
ECF (extracellular fluid)
Term
Potassium balance is not as closely regulated as sodium balance. The retention of potassium occurs when...
Definition
pH falls
Term
Potassium ion excretion increases as...
Definition
ECF concentrations rise, aldosterone is secreted and pH rises
Term
Potassium RETENTION occurs when pH rises or falls?
Potassium EXCRETION increases when pH rises or falls?
Definition
RETENTION = when pH falls ---

EXCRETION = when pH rises
Term
Water loss is balance by gains such as
Definition
eating - drinking - metabolic generation
Term
In the average adult, what is the TOTAL water lost each day? How much is lost just through urine? How much water is lost in feces? How much is lost in respiration and perspiration?
Definition
Total water lost each day - 2500 mL ---

Water lost through urine each day = 1200 mL ---

Water lost in feces = 150mL ---

Water lost in perspiration and respiration = 1150mL
Term
Definition
Term
A drop in filtration pressure stimulates _________________ to release ____________ and ______________
Definition
A drop in filtration pressure stimulates the Juxtaglomerular apparatus (JGA) to release RENIN and ERYTHROPOIETIN
Term
The PCT reabsorbs what percentage of the filtrate produced?
Definition
60-70%
Term
Release of renin by JGA is activated by which ANS?
Definition
sympathetic
Term
Up until fluid reaches the collecting duct, it's known as what?
Definition
filtrate. Once it reaches the collecting duct, it's known as urine
Term
What is countercurrent multiplication?
Definition
Active transport between two limbs of the Loop of Henle where fluid is moving in one direction; responsible for concentration of urine in kidney tubules
Term
What does countercurrent multiplication do and where does it occur?
Definition
It occurs in the ascending and descending limbs of the Loop of Henle. Creates osmotic gradient in medulla. Facilitates reabsorptin of water and solutes before DCT. Permits passive reabsorptin of water from tubular fluid.
Term
Filtration occurs exclusively in the ________ __________ across the ___________ membrane.
Definition
Filtration occurs exclusively in teh renal corpuscle, across the filtration membrane.
Term
Water and solute reabsorption occurs primarily along the ________ __________ _________
Definition
Water and solute reabsorption occurs primarily along the proximal convoluted tubules (PCT)
Term
ACTIVE SECRETION occurs primarily at the _________ and __________ __________ ______________
Definition
proximal and distal convoluted tubules (DCT).
Term
Each kidney has approximately how many nephrons? What is the approximate combined length of these nephrons?
Definition
1.25 million nephrons --- combined length of the nephrons is 85 miles.
Term
The juxtaglomerular complex secretes what?
Definition
the enzyme, renin and the hormone, erythropoeitin
Term
What is macula densa?
Definition
part of what makes up the juxtaglomular apparatus. The region where the epithelial cells of the DCT and their nuclei that are clustered together
Term
What percentage of all nephrons are corticol nephrons?
Definition
85%
Term
Definition