ch. 25 marieb Flashcards

-regulate water volume and osmolarity in the body
-regulate concentration of ions
-ensure acid base balance
-excreting metabolic wastes and drugs/toxins
-produce erythropoietin and renin that regulate RBC production and BP
-convert vitamin D actively (produced in skin, inactively, and activates in kidney and liver)
-filters 200 liters of fluid

-retroperitoneal position between the body wall and the parietal peritoneum
-right kidney crowded by the liver and lies lower than the left
-adrenal gland sits on top of kidney
-lower lumbar position

-leads into the renal sinus
-where the ureter, renal blood vessels, and lymphatics, and nerves all join the kidney

1. renal fascia
2. perirenal fat capsule
3. fibrous capsule

-outer layer of dense fibrous connective tissue
-anchors kidney and adrenal gland to surrounding structures

-fatty mass surround the kidney
-cushions against blows
-holds it against wall

-prevents infections in surrounding regions from spreading to the kidneys

1. cortex
2. medulla
3. pelvis

-granular appearance
-filled with nephrons which are the functioning unit of the kidney

-darkish, reddish brown
-deep to cortex
-pyramids

-cone shaped tissue masses
-made up of collecting tubules and capillaries
-tip of them is the papilla

-separate the renal pyramids

-funnel shaped tubed continuous with ureter leaving the hilum
-form major calyces which subdivide into minor calyces which collect urine that drains from the papilla thru the pelvis into the ureter to the bladder to be stored

-smooth muscle that contracts rhythmically to propel urine

-divides into 5 segmental arteries and branches to form lobar and the interlobar arteries

-renal arteries
-segmental arteries
-lobar arteries
-interlobar arteries
-arcuate arteries
-small cortical radiate arteries (interlobular arteries)
-afferent arterioles

-renal cortex
-cortical radiate
-arcuate vein
-interlobar
-lobar
-renal vein
-empty into inferior vena cava

-network of autonomic nerve fibers, ganglia
-provides nerve supply for the kidney and ureter
-supplied by sympathetic fibers which regulate blood flow by adjusting diameter and influencing the formation of urine by the nephron

-aorta-renal artery-segmental artery-lobar arter-interlobar artery-arcuate artery-cortical radiate artery-afferent arteriole-glomerulus (capillaries)-efferent arteriole-vasa recta-cortical radiate vein-arcuate vein-interlobar vein-lobar vein-renal vein-inferior vein cava

-structural and functional units of the kidneys
-carry out processes that form urine
-contains a renal corpuscle and tubule

-consists of tuft of capillaries called the glomerulus and Bowman's capsule

-completely surrounds the glomerulus

-fenestrated
-exceptionally porous
-allows large amounts of solute-rich to pass from blood into the capsule
-filtrate

-plasma derived fluid
-raw material that the renal tubules process to form urine
-contains everything found in the blood plasma except proteins

1. parietal layer
2. visceral layer

-simple squamous epithelium
-contributes to the structure, but not the formation of filtrate

-contains podocytes

-highly modified, branching epithelial cells
-terminate in the foot processes which cling to the basement membrane
-contains openings between the foot processes called filtration slits which helps filtrate enters the capsular space
-provide for filtration and protect capillaries

1. proximal convoluted tubule
2. nephron loop
3. distal convoluted tubule

-increases in length and enhances its filtrate processing capabilities
-single layer

-cuboidal epithelial cells
-bear dense microvilli which increase surface area and capacity for reabsorption of water and solutes from the filtrate and secreted substances
-bowman's capsule connects directly to here

-AKA the loop of Henle
-descending and ascending limbs
-thick ascending limb
-thin descending limb

-thinner than the PCT and lack microvilli

-principal cells and intercalated cells
-receives filtrate from nephrons
-run thru medullary pyramids
-as they approach the renal pelvis, fuse together to deliver urine thru minor calyces by the papilla

1. principal cells
2. intercalated cells

-short microvilli
-maintain body's water and sodium balance

-abundant microvilli
-types A and B
-maintain acid base balance of the blood

1. cortical nephrons
2. juxtamedullary nephrons

-85% in the kidneys
-located entirely in the cortex

-close to the cortex medulla junction
-play a role in the kidneys' ability to produce concentrated urine
-loop of henle that deeply invades the medulla
-extensive thin segements
-draws a lot of water in due to the long loop of henle
-associated with the vasa recta

1. glomerulus
2. peritubular capillaries

-specialized for filtration
-both fed and drained from arterioles (afferent and efferent)
-helps to maintain high pressure needed for filtration
-efferent arterioles feed into peritubular capillaries or vasa recta

-99%

-cling to renal tubules
-empty into venules
-low pressure so they can readily absorb solutes and water from the tubule cell as they are reclaimed from the filtrate

-efferent arterioles from these long straight vessels that extend deep into the medulla paralleling the loop of henle
-form concentrated urine
-ladder affect signaling exchanges

-we need to be able to absorb and secrete the correct amount

-arterioles are high resistance vessels
-to push out filtrate

-destruction of bowman's capsule

-region where the most distal portion of the ascending limb of henle lies against the afferent arteriole feeding the glomerulus

1. macula densa
2. granular cells
3. extraglomerular mesangial cells

-tall, closely packed cells in the ascending limb
-chemoreceptors that monitor NaCl content of the filtrate entering the distal convoluted tubule
-osmoreceptors

-are in the arteriolar walls
-enlarged smooth muscle cells with secreting granules containing renin
-mechanoreceptors that sense the BP in the afferent arteriole

-between the arteriole and tubule cells
-interconnected by gap junctions
-pass regulatory signals between macula dense and granular
-digest proteins that are on the filtration membrane
-influence capillary filtration
-

-protects glomeruli from fluctuations in systemic blood pressure
-if it constricts, it slows down the blood flow which brings down the blood pressure

-reinforces high glomerular pressure
-reduces hydrostatic pressure in peritubular capillaries
-if this constricts it bring the pressure up

1. glomerular filtration
2. tubular reabsorption
3. tubular secretion

-takes place in the renal corpuscle and produces a cell and protein free filtrate
-glomerulus to bowman’s capsule

-process of selectively moving substances from the filtrate back into the blood
-takes place in the renal tubules and collecting ducts
-anything that is not reabsorbed becomes urine
-tubules to arterioles

-process of selectively moving substances from the blood into the filtrate
-secretion into tubular

-contains uneeded substances such as excess salts and metabolic wastes

-passive process in which hydrostatic pressure forces fluids and solutes thru a membrane
-filtration membrane is more permeable
-high BP
-higher net filtration pressure
-plasma proteins are not filtered and are used to maintain oncotic pressure of the blood
-albumin

-lies between the blood and the interior of the glomerular capsule
-porous membrane that allows free passage of water and solutes smaller than plasma proteins
-fused to podocyte

1. fenestrated endothelium
2. basement membrane
3. foot processes of podocytes of the glomerular capsule

-allow all blood components except blood cells to pass thru

-between the other two layers
-blocks all but the smallest proteins while permitting solutes to pass
-glycoproteins give it a negative charge
-

-contain filtration slits between their foot processes
-slit diaphragms: thin membranes that extend across the filtration slits that prevent almost all macromolecules of the them traveling farther

-maintains the colloid osmotic (oncotic) pressure of the glomerular
-prevents loss of all its water
-prescence of proteins or blood cells in the urine usually indicates a problem with the filtration membrane

1. hydrostatic pressure in glomerular capillaries
2. colloid osmotic pressure in the capsular space

-glomerular blood pressure
-chief force pushing water and solutes out of the blood and across the filtration membrane
-high and remains high across the entire capillary bed

-glomerular capillaries are drained by a high resistance efferent arteriole that feeds them
-filtration occurs along entire length of each glomerular capillary and reabsorption does not occur as it would

-pull filtrate into the tubule

1. hydrostatic pressure in the capsular space
2. colloid osmotic pressure in glomerular capillaries

-pressure exerted by filtrate
-much higher than hydrostatic pressure surrounding most capillaries because filtrate is confined in a small space with a narrow outlet

-pressure exerted by the proteins in the blood

-largely determines the glomerular filtration rate
-blood pressure is influenced by this
-the glomerular hydrostatic pressure – oncotic pressure of glomerular blood combined with the capsular hydrostatic pressure
-can be controlled by changing the diameter of the afferent arterioles

-volume of filtrate formed each minute by the combined activity of all 2 million glomeruli of the kidneys
-proportional to the net filtration pressure
-proportional to total surface area available for filtration
-proportional to filtration membrane permeability

-glomerulus capillaries have a huge surface area
-can fine tune GFR by contracting to adjust the total surface area available for filtration

-thousands of times more permeable than other capillaries because of their fenestrations

-affects the rate of things going thru it
-decrease GFR
-proteins show up in the urine

-BP, GFR
-GFR is directly proportional to the NFP
-changes in the GFR normally results from changes in the glomerular blood pressure

-needed substances cannot be reabsorbed quickly enough an are lost in the urine

-everything is reabsorbed, including wastes that are normally disposed of

1. intrinsic controls (renal autoregulation)
2. extrinsic controls

-adjusting its own resistance to blood flow
-kidney can maintain a nearly constant GFR despite fluctuations in systemic arterial blood pressure

1. myogenic mechanism
2. tubuloglomerular feedback mechanism

-contracts when stretched and relaxes when not stretched
-rising BP stretches vascular smooth muscle in the arteriolar walls, causing the afferent arterioles to constrict
-which restricts blood flow into the glomerulus and prevents glomerular blood pressure from rising to damaging levels
-low BP causes dilation of afferent arterioles and raises glomerular hydrostatic pressure

-directed by the macula dense of the juxtaglomerular complex
-responde to filtrate NaCl concentration

-not enough time for reabsorption and the concentration of NaCl in the filtrate remains high
-macula dense cells respond by releasing vasoconstrictor chemicals that cause intense constriction of the afferent arteriole
-reduce blood flow into glomerulus
-decreases the NFP and GFR, which slows the flow of filtrate and allowing more time for filtrate processing

-slow flowing filtrate inhibits ATP release from macula dense cells
-causes vasodilation of the afferent arterioles
-allows more blood to flow into the glomerulus
-increasing NFP and GFR

1. sympathetic nervous system controls
2. renin angiotensin aldosterone mechanism

-when the volume of the ECF is normal and sympathetic is at rest, renal blood vessels are dilated
-when ECF is low (hypovolemic shock), shunt blood to organs and neural controls override auto regulatory mechanisms
-reduce renal blood flow

-norepinephrine is released by sympathetic nerve fibers and epinephrine is released by medulla which causes vascular smooth muscle to constrict
-increase peripheral resistance
-which brings BP up

-bodys main mechanism for increasing blood pressure

1. direct stimulation of granular cells
2. stimulation of the granular cells by input from activated macula densa cells
3. reduced stretch granular cells

-cause the granule cells to release renin

-low BP (vasoconstriction) of the afferent arterioles by the sympathetic nervous system reduces GFR
-slows down the flow of filtrate thru the renal tubules
-when macula dense cells sense low NaCl concentration, signal granular cells to release renin
-release less ATP

-granular cells act as mechanoreceptors
-a drop in arterial pressure reduces the tension in the granular cells' plasma membranes and stimulates them to release more renin

-vasodilators produced in response to sympathetic stimulation and angiotensin II
-are thought to prevent renal damage when peripheral resistance is increased

-vasodilator produced by the vascular endothelium

-vasoconstrictor of renal vasculature
-works when BP is high

-a powerful vasoconstrictor secreted by capillary cells
-raise systemic BP

-quickly reclaims most of the tubule contents and returns them to the blood
-begins as soon as the filtrate enters the proximal tubules

-requires ATP either directly (primary active transport) or indirectly (secondary active transport)

-encompasses diffusion, facilitated diffusion, and osmosis
-move down their electrochemical gradients

-Na is transported out of the tubule cell by primary active transport
-water sweeps Na into adjacent peritubular capillaries
-low hydrostatic pressure and high osmotic pressure

-active pumping of Na from the tubule cells results in a strong electrochemical gradient that favors its entry at the apical via secondary active transport
-pump maintains the intracellular Na concentration low levels
-K pumped into tubules diffuse into interstitial fluid

-transported substances move through the apical membrane, cystol, basolateral membrane of the tubule cell and then endothelium to the peritubular capillaries

-between the tubule cells

-created by NaK pump
-glucose, amino acids, ions, and vitamins
-Na moves down its concentration gradient

-movement of Na establishes a strong osmotic gradient, water moves by osmosis into the peritubular capillaries
-aquaporins

-aid passive tubular reabsorption of water
-act as water channels across cell membranes
-always present in the tubule cell membranes
-PCT

-presence of aquaporins obliges the body to absorb water in the proximal nephron regardless of over or under hydration

-pass it thru the kidneys and pushes out through the kidney and then we reabsorb most of it, but why does it go into the urine?
-because in the luminal membrane, you have a transport maximum, only a certain number of glucose receptors
-void out the glucose because it can’t take as much
-lack spaces in the membrane to absorb it
-because of TM

-water reabsorption that depends on ADH

-for nearly every substance that is reabsorbed using a transport protein in the membrane
-reflects number of transport proteins in the renal tubules available to carry a substance

-reabsorb glucose, amino acids, and Na and water
-electrolytes
-uric acid and urea

-water
-Na Cl K
-Ca Mg

-Na Cl
-Ca

-Na K HCO Cl
-water
-urea

-leaves the descending but not the ascending
-opposite for solutes, not absorbed in the descending, but both in the ascending

-anti diuretic hormone
-urine output
-makes the principal cells of the collecting ducts more permeable to water by causing aquaporins
-ADH determines number of aquaporins which results in how much water is reabsorbed
-increases urea reabsorption by collecting ducts

-ECF osmolarity decrease
-decrease ADH secretion
-makes ducts impermeable to water

-reabsorption of the remaining Na
-little to no urine leaves the body
-increase blood volume, BP by enhancing Na reabsorption
-reduces K concentrations
-Na enter, K moves out

-decrease blood volume or blood pressure
-causes adrenal cortex to release aldosterone to the blood

-reduces blood Na, decreasing blood volume, decreasing BP

-increases reabsorption of Ca

-reabsorption in reverse
-moves selected substances (H, K, NH, creatinine) from the peritubular capillaries thru the tubule cells into the filtrate

1. disposing of substances
2. eliminating undesirable substances
3. ridding the body of excess K
4. controlling blood pH

-plasma proteins are not filtered, so they substances they bind to are not filtered so they must be secreted

-urea and uric acid

-all K is reabsorbed
-all K in urine comes from aldosterone drive active tubular secretion

-renal tubule cells secrete more H into the filtrate and retain and generate HCO
-blood pH rises and the urine drains of the excess H
-when its too basic, Cl is reabsorbed

1. countercurrent multiplier
2. countercurrent exchanger

-interaction between the flow of filtrate thru the ascending and descending limbs of the loop of Henle

-flow of blood thru ascending and descending parts of the vasa recta

-countercurrent mechanisms that establish and maintain an osmotic gradient extending from the cortex thru the depths of the medulla
-allows kidneys to vary urine concentration

-descending loop of Henle:
-is relatively impermeable to solutes except fro water
-is permeable to water
→ the ascending loop of Henle
-is permeable to solute
-is impermeable to water
-collecting ducts in the deep medullary regions are permeable to urea

-preserves medullary gradient
-prevents rapid removal of salt from the medullary interstitial space
-removes reabsorbed water
-volume of blood at the end of the vasa recta is higher than at the beginning

-overhydrated, ADH production decreases and the osmolarity of urine falls
-if aldosterone is present, the DCT and collecting ducts can removed Na and dilute more
-dehydrated, ADH is released and solute concentration of urine increases

-ADH inhibits diuresis
-99% of the water in filtrate is reabsorbed due to an increased number

-chemicals that enhance the urinary output include:
-any substance not reabsorbed
-substances that exceed the ability of the renal tubules to reabsorb it
-substances that inhibit Na reabsorption
-diuretics

- high glucose levels: carries water out with the glucose
-alcohol: inhibits the release of ADH
-caffeine and most diuretic drugs: inhibit Na ions (furosemide or Lasix) and -Diruil; inhibit Na associated symporters in the ascending loop of Henle so you cannot establish a medullary gradient
-people take it:
-lose weight
-hypertension high BP because they void out water
-CHF
-Congestive heart failure

-refers to the volume of plasma from which the kidneys clear a particular substance in a given time

-clear, plae to deep yellow
-concentrated urine has a deepr yellow color
-drugs, vitamin supplements, and diect can change the color fo urine
-cloudy urine may indicate infection of the urinary tract

-fresh urine is slightly aromatic
-standing urine develops an ammonia odor due to breakdown of urea
-some drugs and vegetables (aspargus and mercaptan) alter the usual odor

-slightly acidic (pH 6) with a range of 4.5 to 8.0
-diet can alter pH

-dependent on solute concentration
-ranges from 1.0001 to 1.035
-used to tell if the person is dehyradted

-tubes covered with smooth muscle
-carry urine to bladder

- smooth, collapsible, muscular sac that temporarily stores urine
-males: prostate gland surrounds the neck inferiorly
-females: anterior to the vagina and uterus
-as the baby develops, it puts pressure on the bladder, so it can’t expand as much as it used to so you pee a lot
-when you go for an ultrasound of the uterus which lies underneath, drink water, so you can inflate bladder, and see it

-when you hold you bladder, the detrusor muscle becomes strained so when you go pee, you don’t empty your bladder all the way, so wait around and drink when you get there

- triangular area outline by the opening for the ureters and the urethra

-urine going back into kidneys

-urethra runs thru prostate gland
-prostate gland: semen formation
-prostate gland can get enlarged (BPH: benign prostatic hypertrophy) collapses the urethra causing poor streaming of urine (they can’t get it out) so they take medication to shrink it up
-urethra shares the ejaculatory duct