Exam 4 - Urinary System Flashcards
What are the four body systems that carry out excretion?
Respiratory, integumentary, digestive, and urinary
What is waste?
Any substance that is useless to the body or present in excess of the body’s needs
What is the normal concentration of blood urea?
10-20mg/dL
What is azotemia?
Elevated BUN (blood urea nitrogen)
What is uremia?
Syndrome of diarrhea, stemming for the toxicity of nitrogenous waste
What is the right kidney slightly lower?
Because of the large right lobe of the liver
What are both the kidneys?
Retripertoneal
What is renal parenchyma?
Glandular tissue that forms urine
What is the renal sinus?
The cavity contains blood and lymphatic vessels and nerves
What are the two zones of renal parenchyma?
Outer renal cortex and inner renal medulla
What does the afferent arterioles do?
Supply one nephron
What drains the blood from the glomerulus?
The efferent arterioles
What do the peritubular capillaries do?
The branch off the efferent arterioles supplying the tissue near the glomerulus
How many nephrons are in each kidney?
1.2 million
What does the renal corpuscle do?
Filters the blood plasma
What does the renal tubule do?
Long, coiled tube that converts the filtrate into urine
What are in the renal corpuscles?
The glomerulus and a two-layered glomerular capsule
What is the vascular pole?
The side of the corpuscle where the afferent arterial enters the corpuscle and the efferent arterial leaves
What is the urinary pole?
The opposite side of the corpuscle where the renal tubule begins
What is the renal tubule?
It is a duct leading away from the glomerular capsule and ending at the tip of the medullary pyramid
What is the proximal convoluted tubule?
It arises from the glomerular capsule, deals with the majority of absorption
What is the nephron loop consist of?
The descending limb and ascending limp with thick and thin segments
Where is the thick segments of the nephron loop?
Initial part of the descending limb and most of the ascending limb
What is the thin segments of the nephron loop?
Lower part of descending limb
What does the thick segment do?
It is engaged in the active transport of salts and have many mitochondria
What does the thin segment do?
The cells are very permeable to water
What is the distal convoluted tubule?
It begins shortly after the ascending limb reenters the cortex
What is the collecting duct?
Receives fluid from the DCTs of several nephrons as it passes back into the medulla
What is the papillary duct?
Formed by merger of several collecting ducts
What is the flow of fluid?
Starts at the glomerular capsule - PCT - Nephron loop - DCT - collecting duct - papillary duct - minor calyx - major calyx - renal pelvis - ureter - urinary bladder - urethra
What are cortical nephrons?
They are short nephron loops, around 85% of them
What are juxtamedullary nephrons?
Long nephron loops, around 15% of them
What is different with juxtamedullary nephrons?
The efferent arterioles branch into vasa recta around long nephron loop
What is different with cortical nephrons?
Efferent arterioles branch into peritubular capillaries around PCT and DCT
What does sympathetic innervation do?
Reduces glomerular blood flow and rate of urine production, it is a response to falling blood pressure
What are the four stages that the kidneys convert blood plasma into urine?
Glomerular filtration, tubular reabsorption, tubular secretion, and water conservation
What is glomerular filtrate?
The fluid in the capsular space
What is tubular fluid?
Fluid from the PCT through the DCT
What is Urine?
fluid that enters the collection duct
What is glomerular filtration?
A special case of capillary fluid exchange in which water and some solutes in the blood plasma pass from the capillaries of the glomerulus into the capsular space of the nephron
What are the three barriers through which fluid passes through the filtration membrane?
Fenestrated endothelium of glomerular capillaries, basement membrane, and filtration slits
What is proteinuria?
Presence of protein in urine
What is hematuria?
Presence of blood in the urine
What do distance runner and swimmers experience temporary proteinuria or hematuria?
Prolonged exercise reducing profusion of kidney
What causes proteinuria and hematuria?
Kidney infections and trauma because they can damage the filtration membrane
What happens if your Glomerular filtration rate is too high?
Fluid flows through renal tubule too rapidly for them to reabsorb the usual amount of water and solutes, urine output rises, and can cause dehydration and electrolyte depletion
What happens if your glomerular filtration rate is too low?
Water are reabsorbed and azotemia may occur
How is GFR controlled?
Adjusting glomerular blood pressure
What are the three homeostatic mechanism that control GFR?
Renal autoregulation, sympathetic control, and hormonal control
What is renal autoregulation?
The ability of the nephrons to adjust their own blood flow and GFR without external control
What are the two types of renal autoregulation?
Myogenic mechanism and tubuloglomerular feedback
What is myogenic mechanism?
It is based on the tendency of smooth muscle to contract when stretched
What does myogenic mechanism do when the arterial blood pressure increases?
The afferent arteriole is stretched so they constrict and prevents blood flow into the glomerulus from changing
What does myogenic mechanism do when the arterial blood pressure decreases?
The afferent arteriole are relaxed so they dilates them and allows blood to flow more easily into the glomerulus
What is tubuloglomerular feedback?
Glomerulus receives feedback on the status of downstream tubular fluid and adjusts filtration rate accordingly
What are the parts of the tubuloglomerular feedback?
Juxtaglomerular apparatus, macula densa, granular cells, and mesangial cells
What is juxtaglomerular apparatus?
Complex structure at the end of the nephron loop where in comes into contact with the afferent and efferent arterioles
What is macula densa?
Patch of sensory cells in nephron loop, when GFR is high filtrate contains more NaCl and it secretes ATP to stimulate nearby granular cells
What is granular cells?
Modified smooth muscle cells around arterioles that constrict afferent arterioles
What is mesangial cells?
Contract, and constrict capillaries
What do granular cells do?
They also secrete renin in response of a drop in blood pressure
What does sympathetic nervous system and adrenal epinephrine do?
Constrict the afferent arterioles in exercise. Reduces GFR and urine output and redirects blood
What are the steps of the RAAS system?
The sympathetic nerve will signal granular cells to release renin while the liver releases angiotensinogen. They concerts it into angiotensin I and when the enzyme ACE from the lungs reacts it turns it into angiotensin II. This goes into brain, causes vasoconstriction, and goes to adrenal gland to release aldosterone
What does angiotensin II do?
It is an active hormone that increases BP
What are the basic stages of urine formation?
Tubular reabsorption, tubular secretion, and water conservation
How much does the PCT reabsorb?
65% of glomerular filtrate
What does the PCT do with the glomerular filtrate?
It removes some substances from blood and secretes them into tubular fluid for disposal in urine
What is tubular reabsorption?
Process of reclaiming water and solutes from tubular fluid and returning them to blood
What is picked up in tubular reabsorption?
All building blocks except sodium
What does the thick segment reabsorb?
25% of Na, K, and Cl in filtrate
What are the two types of cells in the DCT and collecting duct?
Principial cells and intercalated cells
What are principal cells?
Most numerous, they have receptors for hormones, and involved in salt and water balance
What are intercalated cells?
Involved in acid-base balance by secreting H into tubule lumen and reabsorbing K
What is aldosterone?
The salt retaining hormone
What causes aldosterone to be secreted?
When blood Na conc falls or when K conc rises
What secretes aldosterone?
The adrenal cortex
Where does aldosterone effect?
On the thick segment of the nephron loop, DCT, and portion on the collecting duct
What does secreting aldosterone do?
Stimulates reabsorption of Na and secretion of K. Water and Cl follow Na
What are natriuretic peptides?
Secreted by atrial myocardium of the heart in response to high blood pressure
What are the four actions result in excretion of more salt and water in urine which also reduces Blood volume and pressure?
Dilate afferent arteriole and constrict efferent arteriole to raise GFR
Inhibit renin and aldosterone secretion
Inhibit NaCl reabsorption by collecting duct
Inhibit secretion of ADH
What is ADH?
Antidiuretic hormone that is secreted by posterior pituitary
What causes the release of ADH?
Dehydration, loss of blood volume and rising blood osmolarity
What is PTH?
Parathyroid hormone that is secreted from parathyroid glands in response to hypocalcemia (calcium deficiency)
What does PTH do?
Increase phosphate excretion on PCT and increase calcium reabsorption
How much does the nephron loop reabsorb?
25% of the filtrate
What does the DCT reabsorb?
Na, Cl, and water under hormonal control
What is so important about the collecting duct?
It runs through medulla, and reabsorbs water, making urine up to four times more concentrated
How does the water leave the medulla?
As the medulla increases salt levels, the water leaves by osmosis
What is pyuria?
Pus in the urine
What is hematuria?
Blood in urine dur to UTI, trauma, or kidney stones
What is the normal urine volume?
1 to 2 L/day
What is polyuria?
When the urine volume is more then 2 L/day
What is anuria?
When your urine volume is 0 - 100 mL/day
What is diabetes?
Any metabolic disorder resulting in chronic polyuria
What is diabetes mellitus?
When you have high conc of glucose in renal tubule that opposes the osmotic reabsorption of water and more water passes through urine
What is diabetes insipidus?
When ADH hyposecretion causes not enough water to be reabsorbed in collecting duct
What is diuretics?
Any chemical that increases urine volume
What are ureters?
Retroperitoneal, muscular tubes that extend from each kidney to the urinary bladder
What is the urinary bladder?
Muscular sac located on flood of pelvic cavity
What is the urethra?
A tube that coneys urine out of body
What are the parts of the female urethra?
The interna urethral sphincter and the external urethral sphincter
What are the parts of the male urethra?
Prostatic urethra, membranous urethra, and spongey urethra with the internal and external urethral sphincter
What is renal insufficiency?
A state in which the kidneys cannot maintain homeostasis due to extensive destruction of their nephrons
What can renal insufficiency cause?
Reduced production of EPO
