The Urinary System Flashcards
What are the byproducts of metabolism?
CO2, urea, uric acid, etc.
What is the respiratory system responsible for eliminating?
Most of the CO2 from metabolism
What is the urinary system responsible for eliminating?
Much of the other waste products from metabolism
What are the functions of the urinary system?
Regulating blood composition, PH, volume and pressure as well as maintaining blood osmolarity and production of hormones
What are the organs and tissues of the urinary system?
Two kidneys, one bladder, and a urethra
What do the kidneys do?
Filters wastes from the blood and excretes them as urine
What does the urinary bladder do?
Stores urine
What does the urethra do?
Is a tract for urine excretion
What wastes do the kidneys excrete?
Urea, ammonia, creatinine, creatine phosphate, uric acid, drugs, and environmental toxins
How do the kidneys regulate blood ionic composition?
Ion levels found in blood are regulated by increasing/decreasing the amount of urine excreted
How do the kidneys regulate blood pH?
Excretion of H+ and conservation of HCO3-
How do the kidneys regulate blood volume?
conserving or eliminating water in urine
How do the kidneys maintain blood osmolarity?
Separately regulating loss of water and loss of solutes in the urine
How do the kidneys regulate blood glucose?
Performing gluconeogenesis and release glucose into the blood to raise levels
What hormones do the kidneys produce?
Produces calcitriol and erthropoietin
Why is the right kidney slightly lower than the left?
Due to the large size of the liver
What are the 3 layers that surround and protect the internal anatomy of each kidney?
Renal fascia, adipose capsule, and renal capsule
What is the renal fascia?
Dense connective tissue that anchors the kidney to surroundings
What is the adipose capsule?
Fatty tissue that protects the kidney from trauma
What is the renal capsule?
Dense connective tissue that maintains the shape of the kidney and barrier from trauma (deep)
What are the 2 frontal separations of the kidney?
The renal cortex (outer) and renal medulla (inner)
What are renal pyramids?
Cone shaped pyramids in the renal medulla. The base of each pyramid faces the cortex and the apex points towards the renal hilum
What is a renal papilla?
The apex of a renal pyramid called
What are renal columns?
The portions of the cortex that extend between the pyramids
What microscopic structures exist within the parenchymal tissue of the kidney?
The nephrons
Where does filtrate from the nephrons drain into?
Large papillary ducts that extend into the renal papillae of the pyramids
What are renal calyces?
Cup-like structures where filtrate from the papillary ducts drains into
Where does filtrate from the renal calyces drain to?
Into the renal pelvis then out through the ureter to the urinary bladder
What percent of cardiac output does the kidneys receive when the body is at rest?
20-25%
What is the path of renal blood flow?
Renal artery ->
Segmental arteries->
Interlobar arteries->
Arcuate arteries ->
Cortical radiate arteries->
Afferent glomerular arterioles->
Glomerular capillaries->
Efferent glomerular arterioles->
Peritubular capillaries->
Peritubular venules->
Cortical radiate veins->
Arcuate veins->
Interlobar veins->
Renal vein->
What does the renal artery divide into?
Several segmental arteries
What do the segmental arteries branch into?
Several interlobar arteries
What do the interlobar arteries branch into?
Branch two more times until they reach the afferent arterioles
How many afferent arterioles are there for each nephron?
One
Following filtration, what do the glomerular capillaries reunite to form?
Efferent arterioles
What do the efferent arterioles divide into?
Peritubular capillaries
What is the functional unit of the kidney?
The nephron
What are the two parts of the nephron?
The renal corpuscle (blood plasma filtered) and a renal tubule (filtrate flows)
What are the components of the renal corpuscle?
The glomerulus (capillary network) and glomerular capsule (bowman’s capsule)
What are the 3 sections of the renal tubule?
Proximal convoluted tubule, nephron loop (loop of Henle, ascending and descending limb) and the distal convoluted tubule
Where do the distal convoluted tubules of several nephrons drain into?
Several will drain into a single collecting duct
What is the function of the microvilli on the surface of the proximal convoluted tubule?
To increase surface area for reabsorption and secretion
What is the macula densa?
An area of closely packed columnar cells lining the wall of the distal tubule, at the point where the thick ascending limb of the Loop of Henle meets the distal convoluted tubule
What are the juxtaglomerular cells?
Modified smooth muscle fibers on the wall of the afferent arteriole
What is the juxtaglomerular apparatus?
The JG cells and macula densa together
What are the three steps of the formation of urine?
Glomerular filtration, tubular reabsorption, and tubular secretion
What occurs in glomerular filtration?
Water and many blood plasma solutes migrate across the membrane of the glomerular capillaries where they are filtered and move into the glomerular capsule and renal tubule
What occurs in tubular reabsorption?
Majority of filtered water and any usable solutes are reabsorbed and returned to the blood via the peritubular capillaries
What occurs in tubular secretion?
Along the renal tubule and collecting ducts waste substances are secreted into the filt
What factors allow the renal corpuscle to filter higher blood volumes than other blood vessels?
-Large surface area due to length
-Specialized cells contract and relax to increase or decrease surface area based on demand
-The filtration membrane is thin and porous
-Glomerular capillary blood pressure is very high
What are the three pressures that glomerular filtration is dependent on?
Glomerular Blood Hydrostatic Pressure (GBHP), Capsular Hydrostatic Pressure (CHP), and Blood Colloid Osmotic Pressure
What is GBHP?
BP within the glomerular capillaries, promotes filtration by forcing water and solutes through the filtration membrane
What is CHP?
Hydrostatic pressure exerted against the filtration membrane by fluid already in the capsular space (opposes)
What is BCOP?
Caused by the presence of plasma proteins (opposes)
What is Glomerular Filtration Rate (GFR)?
The quantity of filtrate formed in the renal corpuscles of both kidneys per minute
What are the two ways GFR is regulated?
Adjusting blood flow to the glomerulus and altering glomerular capillary surface area
What are the two hormones that contribute to regulation of GFR?
Angiotensin II and Atrial Natriuretic Peptide (ANP)
Where does the majority of reabsorption of water and solutes occur?
In the proximal convoluted tubule (PCT)
What is responsible for the “fine tuning” of reabsorption for homeostatic balance?
The nephron loop and distal convoluted tubule (DCT)
What solutes are reabsorbed?
Na+, K+, Ca2+, Cl-, CO3-, HPO42-, glucose, amino acids, urea, small protiens, peptides
What substances are excreted in urine?
H+ (pH regulation), K+, NH4+ (ammonium), creatine, drugs, alcohol
How does the Renin-Angiotensin-Aldosterone System (RAAS) effect reabsorption and secretion?
When renin is secreted (in times of low blood volume and pressure), it starts the system of converting until we reach angiotensin II which enhances reabsorption of Na+ and H2O in the PCT. Aldosterone then further promotes reabsorption of Na+ and secretion of K+.
How does ADH effect reabsorption and secretion?
Promotes water reabsorption by increasing water permeability in the principle cells of the tubule and duct of the PCT
What does the ureters do?
Each kidney has a single ureter that transports urine from the renal pelvis to the urinary bladder
What assists urine flow in the ureter?
Peristalsis, hydrostatic pressure, and gravity
What prevents backflow of urine in the ureters?
A physiological “valve”. Pressure from a full bladder collapses the openings where ureters enter.
What prevents contact of urine with the actual cells of the ureters?
The mucosal membrane secretes a mucous that prevents contact
What is peristalsis?
A progression of coordinated contractions and relaxations of muscle fibers to push urine onwards
What is the urinary bladder?
A hollow distensible muscular organ, spherical when filled with urine and pear shaped when overly full. Contains an internal urethral sphincter and an external urethral sphincter.
How much urine can the bladder hold?
500-700ml, urge to void at 200-400ml
What is the urethra?
A small tube leading from the floor of the bladder to the exterior of the body. Terminal passageway for urine in both males and females
What are the differences in urethras in males and females?
Males:
-5 times longer
-Common passageway for urine and reproductive system
-Divided into 3 segments and passes through the reproductive tract
Females:
-Shorter than males, making females far more susceptible to UTIs
-Separate from the reproductive tract
What is urinary incontinence?
A lack of voluntary control over micturition
What is glucosuria?
glucose in the urine caused by elevated blood glucose levels
What are the 3 main types of diuretics?
Loop (inhibits reabsorption of Na+, K+, and Cl- in the nephron loop), Thiazide (inhibits Na+ reabsorption in the DCT), and Potassium Sparing (aldosterone antagonist in the DCT)
What does the urinary system do for the integumentary system?
Contributes to synthesis of calcitriol (VitD)
What does the urinary system do for the skeletal system?
Adjusts calcium and phosphate levels
What does the urinary system do for the muscular system?
Adjust blood levels of calcium
What does the urinary system do for the nervous system?
Gluconeogenesis, provides glucose for ATP production
What does the urinary system do for the endocrine system?
Releases erythropoietin - stimulates RBC production
What does the urinary system do for the cardiovascular system?
regulates BP by altering H2O reabsorption
What does the urinary system do for the lymphatic and immune system?
Regulates fluid volume. Urine flushes microbes out of the urethra
What does the urinary system do for the respiratory system?
Work cooperatively with lungs to adjust pH levels
What does the urinary system do for the digestive system?
contribute to the synthesis of calcitriol (VitD)
What does the urinary system do for the all bodily systems?
Regulates volume, composition and pH of all body fluids by removing wastes and excess substances from the blood
