Ch 7 Urinary Function Flashcards
where are the kidneys located?
in the retroperitoneal space
what are the functions of the urinary function?
regulates fluid volume, blood pressure, metabolic waste and drug excretion, vitamin D conversion, pH regulation, and hormone synthesis
renal capsule
connective tissue surrounding the kidneys
renal cortex
the area directly beneath the renal capsule that contains the functional units of the kidney, the nephrons
supplies the kidney with blood
renal artery
renal hilum
the opening in the kidney through which the renal artery and nerves enter and the renal vein and ureter exit
renal pelvis
what the central portions of the renal sinus enlarge to form. urin drains into the renal pelvis through tubes called calyces
what do calyces drain urine into?
the ureters
what do ureters do?
transport urine to the bladder using peristaltic actions
what are the functions of the kidneys?
eliminate waste from the blood; help regulate body water concentration; help regulate blood pressure; help maintain a constant blood pH
what is the function of the urinary bladder?
stores urine; contracts to eliminate stored urine
what is the function of the urethra?
transports urine to the outside of the body from the urinary bladder
what gives us the urge to urinate?
as the volume of urine in the bladder increases, the urine exerts pressure on the two bladder sphincters and stretch receptors of the bladder. a pressure of 200-300 mL on the sphincters and receptors sends messages to the brain, triggering the urge to urinate
what occurs when urination is initiated?
the bladder contracts and the external sphincter relaxes, forcing urine out through the urethra
how long is the urethra in females? how long is it in males?
approximately 1.5 inches long in women and about 6-8 inches long in men
what things make a woman more susceptible to urinary tract infections than men?
shorter urethra, in combination with sitting for urination
similar to a funnel with a long stem. contains multiple sections and each section is responsible for excreting or reabsorbing specific substances
nephron
how many nephrons are in one kidney?
1-2 million
the proximal convoluted tubule enlarges into a double membrane chamber called…
Bowman’s capsule
Bowman’s capsule surrounds a cluster of capillaries called…
the glomerulus
this determines the amount of urine made and is necessary for healthy renal function
the blood supply to the glomerulus
what is the glomerular filtration rate (GFR)
the speed at which blood moves through the glomerulus
what is normal GFR and normal urine output?
GFR ~125mL/min
urine output ~1500mL/day
what are the three most significant metabolic wastes that the kidneys manage?
ammonia, uric acid, and urea
a highly toxic chemical that results from the breakdown of amino acids in the liver
ammonia
why does amino acid breakdown generally occur?
in the presence of excess protein or deficient carbs in the diet
deamination
when amino acids are broken down and the amino groups are stripped from the molecules
how is urea formed?
amino acids are broken down and the amino groups are stripped from the molecules, these amino groups are converted to ammonia following deamination and then most of this ammonia is converted to urea in the liver
how does liver disease affect urea production?
it can impair the production of urea because it makes urea from ammonia, so liver disease can lead to high levels of ammonia in the blood
what does uric acid production result from? what is it a by-product of? and what can excess levels lead to?
the breakdown of nucleotides. by-product of metabolism in the liver. excess levels can lead to gout, which results in uric acid crystal deposits in the joints
aside from ammonia, urea, and uric acid, what are other elements normally found in the urine?
sodium, potassium, and small amounts of protein and bacteria
the kidneys are responsible for converting which vitamin to its active form?
vitamin D
what does vitamin D do when it is in its active form?
aids in calcium and phosphorus absorption
how do the kidneys regulate pH?
by secreting bicarbonate and excreting hydrogen
what do the kidneys release in response to hypoxia? what does this do?
release erythropoietin. this stimulates the bone marrow to produce more red blood cells. if iron levels are adequate, an increase in red blood cells increases oxygen-carrying capacity, thus decreases hypoxia
what can happen when the aging individual experiences less filtration capability?
this may lead to waste accumulation and loss of homeostatic regulation
why may an aging person require an alternative medicine dose?
they may need a smaller dose, or doses spaced further apart to prevent drug toxicity because of impaired filtration
what affect does increased ADH levels have on the kidney?
collecting ducts and distal convoluted tubules become permeable to water; water moves out of the ducts and into the blood
what affect does decreased ADH levels have on the kidneys?
collecting ducts become impermeable to water; water is not reabsorbed from the filtrate and is excreted
what affect does increased aldosterone levels have on the kidneys?
tubules increase reabsorption of sodium from the filtrate and decrease reabsorption of potassium; water and sodium thus move from filtrate into the blood, and excess potassium is excreted
what affect do decreased levels of aldosterone have on the kidney?
tubular absorption of sodium and potassium is normal; water is not reabsorbed from the filtrate and is excreted
conditions that alter urination may include what two things?
structural barriers or problems with the act of urination
conditions that impair renal function include what disorders?
those that prevent the kidney from regulating fluid and electrolytes as well as excreting waste products or other substances
what things does the act of urination require?
a functioning bladder with stretch receptors to sense the filling of urine, an intact parasympathetic pelvic nerve to transmit the signal, and working detrusor muscles to initiate bladder contractions to expel the urine
what things prevent inappropriate urination?
sympathetic innervations to the detrusor muscle and the internal sphincter
how can upper motor impulses delay voiding?
by tightening the urethral sphincter
what will happen if the urge to void is ignored too long?
bladder contractions take over the neural delaying mechanism and involuntary urination occurs
any infections that begin in the urinary tract
urinary tract infections
what part of the urinary tract is the most frequent site for infection?
the lower urinary tract - bladder and urethra
what are UTI caused by? what is the most frequent cause?
they are caused by a direct invasion of the urinary tract by bacteria. most commonly caused by bacteria from the digestive tract - E. coli
why is urine an excellent medium for microorganism growth?
because of its protein content
what mechanisms does the urinary system have to prevent infection?
one-way valves where the ureters attach to the bladder; urination, which washes microbes out of the body; prostate secretions that slow bacterial growth in men; and the immune system
what are the two ways that bacteria can invade the urinary system?
through the urethra, ascending into the urinary tract. but occasionally it can invade the kidneys through the blood
why are women more vulnerable to UTIs than men?
they have shorter urethras so the microorganism has a shorter distance to travel, women usually urinate in a sitting position which prevents full emptying of the bladder, women may experience increased perineal tissue irritation from sexual activity, bubble baths, bathing suits, tight-fitting clothing, and deoderants, as well as nylong, lace, and thong underwear
why are men likely to have a recurrent UTI?
bacteria can hide deep inside the prostate tissue
what are some risk factors for developing UTI?
being a woman, benign prostatic hypertrophy, congenital urinary tract abnormalities, immobility, urinary or bowel incontinence, renal calculi, decreased cognition, pregnancy, impaired immune response, impaired nerve innervations, urinary cathetarization, improper personal hygiene, using a diaphragm or spermicide for birth control, using unlubricated condoms
how does benign prostatic hypertrophy contribute to causing a UTI?
causes urinary retention
how does congenital urinary tract abnormalities cause UTIs?
alter urinary flow
how does immobility cause a UTI
prevents complete bladder emptying, leading to urinary stasis
how does urinary or bowel incontenence contribute to the developement of a UTI?
can increase the potential for contamination of the urinary meatus
how do renal calculi contribute to the development of a UTI?
obstruct urine output, leading to urinary stasis
how does decreased cognition cause UTI?
increases the risk for incontenence and toileting issues