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T2: Urinary
Ch. 45: Urinary System
Question | Answer |
---|---|
What are the primary functions of the kidneys? | Regulate the volume and composition of extracellular fluid (ECF) and excrete waste products from the body. |
What are some other functions of the kidneys? | Control blood pressure, produce erythropoietin, activate Vitamin D, and regulate acid-base balance. |
Where are the kidneys located? | Retroperitoneally (behind the peritoneum) on either side of the vertebral column at about the level of the 12th thoracic (T12) vertebra to the 3rd lumbar (L3) vertebra. Right kidney is positioned at the level of the 12th rib, is lower than the left. |
A thin, smooth layer of fibrous membrane that covers the surface of each kidney. | capsule |
Function of the capsule | Protects the kidney and serves as a shock absorber when this area is traumatized from a sudden force or strike. |
On the medial side of the kidney serves as the entry site for the renal artery and nerves and as the exit site for the renal vein and ureter. | hilus |
Outer layer of the kidney | cortex |
Inner layer of the kidney and consists of a number of pyramids. | medulla |
The apices (tops) of these pyramids through which urine passes to enter the calyces. | papillae |
The minor calyces widen and merge to form major calcyes, which form a funnel-shaped sac. Urine is transported to this, from which it drains through the ureter to the bladder. | renal pelvis |
How much urine can the renal pelvis store? | 3-5 mL |
What is the functional unit of the kidney? | nephron |
How many nephrons are in each kidney? | approx. 1 million |
What is the nephron composed of? | the glomerulus, Bowman's capsul, and a tubular system |
What does the tubular system consist of ? | the proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting tubules. |
Where is the glomerulus, Bowman's capsule, proximal tubule, and distal tubule located? | in the cortex of the kidney |
Where is the loop of Henle and collecting tubules located? | in the medulla |
Several collecting tubules join to form a single _____ which eventually merge into a pyramid that empties via the papilla into a minor calyx. | collecting duct |
How much blood flows to the kidneys per minute? | approx. 1200 mL/min |
What percentage of blood flow do the kidneys need? | 20%-25% |
Blood reaches the kidneys via the _____, which arises from the _____, and enters the kidney through the _____. | renal artery; aorta; hilus |
The renal artery divides into secondary branches and then into still smaller branches, each of which forms an? | afferent arteriole |
The afferent arteriole divides into a capillary network, the _____, which is a tuft of up to 50 capillaries. | glomerulus |
Urine formation is the outcome of what? | filtration, reabsorption, secretion, and excretion of water, electrolytes, and metabolic waste products |
Urine formation begins at this semipermeable membrane, in which blood is filtered. | glomerulus |
In the glomerular capillaries, what causes a portion of blood to be filtered across the semipermeable membrane into the Bowman's capsule, where the filtered portion of the blood, the glomerular filtrate, begins to pass down to the tubule. | hydrostatic pressure |
This is the amount of blood filtered each minute by the glomeruli. | glomerular filtration rate (GFR) |
normal GFR | 125 mL/min |
Carry out the functions of reabsorption and secretion. | tubules and collecting ducts |
The passage of a substance from the lumen of the tubules through the tubule cells and into the capillaries. | reabsorption |
Reabsorption involves what mechanisms? | active and passive transport |
The passage of a substance from the capillaries through the tubular cells into the lumen of the tubule. | tubular secretion |
A hormone produced in the kidneys and secreted in response to hypoxia and decreased renal blood flow. | erythropoietin |
Erythropoietin stimulates this in the bone marrow. | RBC production |
This is important in the regulation of BP. | renin |
Where is renin produced and secreted? | in the juxtaglomerular cells of the kidney |
Renin is released into the bloodstream in response to what? | decreased renal perfusion; decreased arterial BP; decreased ECF, decreased serum Na concentration; increased urinary Na concentration |
What is the job of renin? | activates angiotensinogen (from the liver) to angiotensin I |
What happens to angiotensin I? | Is converted to angtiotensin II by angiotensin-converting enzyme (ACE) |
What does angiotensin II stimulate? | the release of aldosterone from the adrenal cortex |
What is the function of aldosterone? | causes Na and water retention, leading to an increased ECF volume |
Angiotensin II causes increased? | peripheral vasoconstriction |
What happens to renin when there is an elevation in BP? | release of renin is inhibited |
Are tubes that carry urine from the renal pelvis to the bladder. | ureters |
The narrow area at which point each ureter joins the renal pelvis. | ureteropelvic junction (UPJ) |
The ureters insert into either side of the bladder base at the? | ureterovesical junctions (UVJs) |
The narrow ureteral lumens can be easily obstructed by? | internally - urinary calculi; externally - tumors, adhesions, inflamamtion |
Stretchable organ behind the symphysis pubis and anterior to the vagina and rectum. | bladder |
What is the function of the bladder? | To serve as a reservoir for urine and to eliminate waste products from the body. |
What is normal adult urine output? | approx. 1500 mL/day, which varies with food and fluid intake |
The triangular area formed by the two ureteral openings and the bladder neck at the base of the bladder. | trigone |
The bladder muscle, composed of layers of intertwined smooth muscle fibers capable of considerable distention during bladder filling and contraction during emptying. | detrusor |
How much urine can the bladder hold? | varies but generally range from 600-1000 mL |
Evacuation of urine. | urination, micturition, or voiding |
A small tube that incorporates the smooth muscle of the bladder neck and extends to the striated muscle of the external meatus. | urethra |
What is the primary function of the urethra? | To serva as a conduit for urine from the bladder to outside the body during voiding and to control voiding. |
length of female urethra | 1-2 inches (3-5 cm) |
length of male urethra | 8-10 inches (20-25 cm) |
Stimulating and inhibiting impulses are sent from the brain through what areas of the spinal cord to control voiding? | through the thoracolumbar (T11-L2) and sacral (S2-S4) areas |
Distention of the bladder stimulates this within the bladder wall. | stretch receptors |
What causes a desire to urinate? | Impulses are transmitted to the sacral spinal cord and then to the brain. |
If the time to void is not appropriate then what occurs? | Inhibitor impulses in brain r stimulated & transmitted back thru thoracolumbar & sacral nerves innervating the bladder. Detrusor muscle accomm. to pressure (doesnt contract) & sphincter& pelvic floor muscles tighten (contract) to resist bladder pressure. |
What occurs if the time to void is appropriate? | Cerebral inhibition is voluntarily suppressed, impulses transmitted via the spinal cord for bladder neck, sphincter, & pelvic floor muscles to relax & for bladder to contract. |
When the bladder is empty, what happens? | The sphincter closes and the detrusor muscle relaxes. |
Between the ages of 30 and 90 what happens to the kidneys? | size and weight decrease 20-30% |
What happens to the kidneys by the seventh decade? | loss of 30-50% of glomerular function |
What can accelerate the decrease of renal size with age? | atherosclerosis |
Decreased renal blood flow results in? | decreased GFR |
Altered hormonal levels, including ADH, aldosterone, and ANP result in? | decreased ability to concentrate urine and altered excretion of water, sodium, potassium, and acid |
As a woman ages what happens to the urethra, bladder, vagina, and pelvic floor? | undergo a loss of elasticity and muscle support |
Older women are more prone to what? | bladder infections and incontinence |
What occurs to the urinary system as men age? | The prostate enlarges and may affect urinary patterns, causing hesitancy, retention, slow stream, and bladder infections. |
Kidney enlargement is suggestive of what? | neoplasm or other serious renal pathologic conditions |
Tenderness in the flank area may be detected by what? | fist percussion (kidney punch) |
How is fist percussion (kidney punch) performed? | By striking the fist of one hand against the dorsal surface of the other hand, which is placed flat along the posterior CVA margin. NOrmally, a firm blow in the flank area should not elicit pain. |
The presence of CVA tenderness and pain may indicate what? | a kidney infection or polycystic kidney disease |
When is the bladder percussible? | not until it contains 150 mL of urine |
If the bladder is full, what is heard above the symphysis pubis? | dullness |
A distended bladder may be percussed as high as the ? | umbilicus |
The bell of the stethoscope may be used to auscultate over both CVAs and in the upper abdominal quadrants. With this technique what would you auscultate for? | bruits (an abnormal murmur) that is heard over the abdominal aorta and renal arteries |
If a bruit is heart what would this indicate? | impaired blood flow to the kidneys |
What are some diagnostic studies of the urinary system? | urinalysis, creatinine clearance, urodynamics |
One of the first studies done to evaluate disorders of the urinary tract. Results may indicate possible abnormalities, suggest the need for further studies, or provide evidence of progression in a previously diagnosed disorder. | urinalysis |
With a urinalysis when is the best time to obtain a specimen? Why? | The first morning void is more likely to contain abnormal constituents if they are present. |
With a urinalysis when should the urine be examined and why? | Within 1 hour of urination because bacteria multiply rapidly, RBC hemolyze, casts (molds of renal tubules) disintegrate, and the urine becomes alkaline as a result of urea-splitting bacteria. |
If it is not possible to send the specimen to the laboratory immediately what should be done with the urine sample? | it should be refrigerated |
The result of this test closely approximates that of the GFR. | creatinine clearance |
A blood specimen for serum creatinine determination should be obtained during? | the period of urine collection |
Measure urinary tract function by studying the storage of urine within the bladder and the flow of urine through the urinary tract to the outside of the body. | urodynamic studies |
An evaluation of bladder tone, sensations of filling and bladder stability. Water or saline is instilled into the bladder through a urinary catheter. | cystometrography |
What are some expected effects of a cystoscopy? | burning on urination, pink-tinged urine, and urinary frequency |