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105 Cards in this Set
- Front
- Back
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What are the components of the urinary system?
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-two kidneys
-two ureters -one urinary bladder -one urethra |
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What do the kidneys do?
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-make urine and carry out other vital functions
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What do the ureters do?
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-carry urine to the urinary bladder
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What does the urinary bladder do?
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-collects, stores, and releases urine
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What does the urethra do?
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-empties urine from the body
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What are 6 functions of the urinary system?
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-eliminating organic waste products, such as urea
-regulating blood volume and pressure -regulating plasma concentrations of ions -helping stabalize blood pH -conserving nutrients -assisting the liver in detoxifying poisons |
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How does the urinary system regulate blood volume and pressure?
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-adjusting the volume of water lost
-releasing erythropoietin and renin |
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How does the urinary system help stabilize blood pH?
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-by controlling loss of hydrogen ions and bicarbonate ions in urine
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What is the gross anatomy of kidney?
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-bean shaped
-smooth surface (except cattle) |
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What is the hilus of the kidney?
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-point of entry for renal artery and renal nerves
-point of exit for renal vein and ureter |
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How many renal pyramids are typically in each kidney?
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-6 to 18
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Where does the tip of each pyramid go and what are they called?
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-renal papilla project into minor calyces
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What are renal columns?
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-cortical tissue that passes between pyramids
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What is a renal lobe?
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Produces urine and consists of: -renal pyramid
-overlying area of renal cortex -adjacent tissues of renal columns |
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What path does urine take to get to the bladder?
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-renal papilla
-minor calyx -major calyx -renal pelvis -ureter |
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How much of cardiac output do the kidneys recieve?
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-20 to 25% of total cardiac output
-1200 mL of blood flows through kidneys each minute -kidney recieves blood through renal artery |
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How does blood get from the renal artery to the renal vein?
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-renal artery
-segmental arteries -interlobar arteries -arcuate arteries -interlobular arteries -afferent arterioles -nephrons -venuoles -interlobular veins -arcuate veins -interlobar veins -renal veins |
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What is the functional unit of the kidney?
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-nephron
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What does the nephron consist of?
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-renal corpuscle
-renal tubule |
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What parts make up the renal tubule?
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-proximal convoluted tubule
-the loop of Henle -distal convoluted tubule |
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What makes up the renal corpuscle?
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-Bowmans capsule
-glomerulus |
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What is Bowman's capsule?
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-forms the outer wall of the renal corpuscle
-encapsulates the glomerular capillaries |
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What is the glomerulus?
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-capillary network inside Bowmans capsule
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What are the two epitheliums that make up Bowman's capsule?
What is the space between them? |
-parietal
-vesceral -capsular space |
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What is the perietal epithelium made of?
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-a simple squamous epithelium, forms the outer wall
-continuous with visceral epithelium |
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What does the visceral epithelium cover?
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-covers glomerular capillaries
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What does the visceral epithelium consist of?
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-large cells (podocytes)
-have complex processes or "feet" that wrap around specialized lamina densa of glomerular capillaries -have filtration slits |
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What are filtration slits in visceral epithelium?
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-narrow gaps between adjacent pedicels
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What delivers blood to the glomerulus? From the glomerulus?
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-afferent arteriole
-efferent arteriole |
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Once blood leaves glomerulus through efferent arteriole, where does it go?
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-flows into peritubular capillaries
-drains into small venules |
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What type of capillaries are in the glomerulus and how many?
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-fenestrated capillaries
-50 intertwining capillaries |
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What is the proximal convoluted tubule?
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-first part of renal tubule nearest to Bowman's capsule
-follows a winding, convoluted course |
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What is the loop of Henle?
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Consists of:
-a descending limbs -a sharp turn -an ascending limb -each limb contains a thick segment and a thin segment |
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Where is the distal convoluted tubule?
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-convoluted tubule beyond the loop of Henle
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What are the parts of the renal tubule?
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-proximal convoluted tubule
-loop of Henle -distal convoluted tubule |
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What are collecting ducts for and where are they?
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-receive fluid from many nephrons
-begin in cortex, descend into medulla, carry fluid to papillary duct that drains into a minor calyx |
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Describe the cortical nephrons
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-85% of all nephrons
-located mostly within superficial cortex of kidney -loop of Henle is relatively short -efferent arteriole delivers blood to a network of peritubular capillaries (which surround entire renal tubule |
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Describe juxtamedullary nephrons
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-have long loops of Henle that extend deep into medulla
-peritubular capillaries connect to vasa recta (long, straight capillaries parallel with loop of Henle) |
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What is the goal of urine production?
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-maintain homeostasis by regulating volume and composition of blood including excretion of metabolic waste products
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What is urea?
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-the most abundant organic waste
-produced during the breakdown of amino acids |
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What is creatinine?
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-generated in skeletal muscle tissue by breakdown of high-energy compound, creatine phosphate
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What is uric acid?
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-formed by the recycling of nitrogenou sbases from RNA molecules
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What are the three basic processes of urine formation?
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-filtration
-reabsorption -secretion |
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What causes filtration in urine formation?
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-blood pressure forces water and small solutes across membrane into capsular space.
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During reabsorption in urine formation, where do molecules go?
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-out of tubule and into the peritubular blood
*selective process |
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What is the difference between the secretion and reabsorption of molecules?
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-secretion moves molecules out of peritubular blood and into the tubule for excretion instead of into peritubular blood.
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What makes up the filtration membrane?
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-capillary endothelium
-lamina densa -filtration slits |
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What forces move water through membrane pores?
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-hydrostatic pressure forces water through membrane pores
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What molecules can move through filtration pores?
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-metabolic wastes and excess ions
-glucose, free fatty acids, amino acids, and vitamins |
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What is glomerular filtration governed by?
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-glomerular hydrostatic pressure
-capsular hydrostatic pressure -blood colloid osmotic pressure |
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What are the three filtration pressures?
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-glomerular filtration
-net hydrostatic pressure -filtration pressure |
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What is glomerular hydrostatic pressure?
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-45 to 55 mm Hg blood pressure
-significantly higher than capillary pressures in systemic circuit |
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What is capsular hydrostatic pressure
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-opposes GHP, approximately 15 mm Hg
-results from resistance to flow along nephron and conducting system |
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What is blood colloid osmotic pressure?
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-osmotic pressure resulting from presence of suspended proteins
- about 25 mm Hg |
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What is Net hydrostatic pressure?
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GHP-CsHP
-about 35 mm Hg |
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What is filtration pressure?
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NHP-BCOP
-about 10 mm Hg |
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What is the glomerular filtration rate?
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-GRF
-the amount of filtrate produced in the kidneys each minute -about 125 mL per min in human -any factor that alters the filtration pressure will change the GFR |
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At what blood pressure will kidney filtration cease?
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-when it drops by 20%
*very sensitive to changes in blood pressure |
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What are the three levels of GFR control?
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-autoregulation (local level)
-hormonal regulation (initiated by kidneys) -autonomic regulation (by sympathetic divisions of ANS) |
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What is the purpose of autoregulation in GFR control?
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-maintains GFR despite changes in local blood pressure and blood flow
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What does reduced renal blood pressure trigger in autoregulation?
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-dilation of afferent arteriole
-dilation of glomerular capillaries -constriction of efferent arterioles |
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What does a rise in renal blood pressure cause in autoregulation of GFR?
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-stretches walls of afferent arterioles
-causes smooth muscle cells to contract -constricts afferent arterioles -decreases glomerular blood flow |
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What are some hormonal regulations of GFR?
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-atrial natriuretic peptides
-renin-angiotensin system |
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What is atrial natriuretic peptides?
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-released by heart in response to stretching walls and due to increased blood volume or blood pressure
-trigger dilation of afferent arterioles and constriction of efferent arterioles -elevates glomerular pressures and increases GFR |
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What is the renin-angiotensin system?
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-decline in blood pressure causes the juxtaglomerular apparatus to release renin
-renin stimulates production of angiotensin I and II (by liver) |
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What types of fibers mostly make up autonomic regulation?
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-sympathetic postganglionic fibers
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What does sympathetic activation cause in autonomic regulation?
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-constricts afferent arterioles
-decreases GFR -slows filtrate production |
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How can changes in kidney blood flow due to sympathetic stimulation be opposed?
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-at local level by autoregulation
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How does the filtrate compare to blood plasma which is a result of glomerular filtration?
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-very similar but none (or very few) plasma proteins
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Where does reabsorption and secretion occur?
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-in every segment of nephron except in renal corpuscle
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Where do reabsorbed materials go?
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-enter peritubular fluid and diffuse into peritubular capillaries
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At the kidney level, what transport activities are there?
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-diffusion
-osmosis -channel-mediated diffusion -carrier-mediated transport |
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What is the renal threshold?
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-the plasma concentration where a specific compound or ion begins to appear in urine
-varies with the substance involved -renal threshold for glucose approximately 180 mg/dl |
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Where does the most reabsorption and secretion occur in the kidneys?
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-proximal convoluted tubule
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What things are reabsorbed in the proximal convoluted tubule?
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-filtrate produced in the renal corpuscle (60-70%)
-glucose, a.a., other organic nutrients (99-100%) -actively reabsorb ions (60-70%) -passively reabsorb urea, Cl-, and lipid-soluble materials |
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What does the proximal convoluted tubule secrete?
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-H+, NH4+, creatinine, drugs, toxins
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What process reabsorbs fluid and molecules in the Loop of Henle?
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-countercurrent multiplication
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What does the descending limb of Henle's loop look like?
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-thin
-permeable to water -impermeable to solutes |
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What does the ascending limb of Henle's loop look like?
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-impermeable to water
-active solute transport |
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How does the countercurrent multiplication and concentration of urine use a positive feedback loop?
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-pumps out Na and Cl to elevate osmotic conc. in peritubular fluid
-osmotic flow out of descending limb -now highly conc soln moves into ascending limb accelerates transport of Na and Cl into peritubular fluid |
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What are two benefits of countercurrent multiplication?
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-efficiently reabsorbs solutes and water (before tubular fluid reaches DCT and collecting system)
-establishes concentration gradient (permits passice reabsorption of water from tubular fluid in collecting system) |
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How much of original filtrate volume reaches DCT?
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-15 to 20%
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What dictates reabsorption of water in DCT?
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-ADH stimulation
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What dictates reabsorption of Na+ in DCT?
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-aldosterone stimulation
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What is secreted at DCT?
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-H+
-NH4+ -creatinine -drugs -toxins |
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What does the collecting system secrete and why?
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-H+
-HCO3- -controls body fluid pH |
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What is obligatory water reabsorption?
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-water absorption in teh proximal convoluted tubule and the descending limb of the loop of Henle
-can NOT be adjusted -recovers 85% of filtrate |
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What is facultative water reabsorption?
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-the amount of water reabsorbed along the distal convoluted tubule and the collecting system
-can be precisely controlled (because segments are relatively impermeable to water except in the presence of ADH). |
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What are the two types of reabsorption methods in urine volume control?
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-obligatory water reabsorption
-facultative water reabsorption |
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What are the hormones that play a part in controlling urine volume?
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-ADH
-Aldosterone -Atrial natriuretic hormones (ANH) |
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What does ADH do in urine control?
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-controls the permeability of the distal convoluted tubule and collecting system to water
-by increasing special water channels in the apical cell membranes |
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What does aldosterone do?
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-controls sodium ion pumps along most of the distal convoluted tubule and the proximal portion of the collecting system
-raise the sodium concentration of blood and thus promoting reabsorption of water |
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What does atrial natriuretic hormones do?
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-promotes loss of sodium via urine
-opposes aldosterone -cause the kidney to reabsorb less water and thereby produce more urine |
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What is the vasa recta?
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-returns solutes and water reabsorbed in medulla to general circulation without disrupting the concentration gradient
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Describe acidemia.
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-pH of plasma falls below 7.35
-physiological state called acidosis |
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Describe alkalemia.
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-pH of plasma rises about 7.45
-physiological state result is called alkalosis |
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What are the limits of plasma pH where animals can't survive?
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-<6.8
->7.7 |
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What are the triple actions used to prevent abnormal pH developments
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-buffer system
-respiratory compensation -renal compensation |
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What are the three parts of the buffer system?
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1) carbonic acid-bicarbonate buffer system
2) phosphate buffer system 3) protein buffer system |
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How does the respiratory compensation affect the carbonic acid-bicarbonate buffer system?
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-by the pulmonary ventilation
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What occurs with renal compensation?
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-kidneys excrete alkaline or acidic urine as needed
-vary rates of H+ secretion and HCO3- reabsorption (depending on the pH of the ECF) |
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What is the normal composition of urine?
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pH: 6
U.G: 1.003-1.030 osmolarity: 855-1335 water: 93-97% volume: 1200 ml/day color: clear yellow odor: varies w/composition bact content: sterile |
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What is urination called?
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micturition
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How do signals begin and travel as bladder fills?
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-stretch receptors stimulate sensory fibers in pelvic nerve
-afferent fibers to sacral spinal cord -efferent fibers stimulate ganglionic neurons in wall of bladder -postganglionic neuron in intramural ganglion stimulates detruscor muscle contraction -interneuron relays sensation to thalamus -projection fibers from thalamus deliver sensation to cerebral cortex |
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What is the last step of micturition?
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-voluntary relaxation of external urethral sphincter
-this causes relacation of internal urethral sphincter |
