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177 Cards in this Set
- Front
- Back
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The urinary system consists of what organs?
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Kidneys, ureters, urinary bladder, urethra
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As a general overview what are the functions of the kidney?
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Regulation of the following concerning blood: ionic composition, pH, osmolarity, glucose level, volume, pressure.
It also releases erythropoietin and calcitriol, as well as the excretion of wastes and foreign substances. |
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What is the renal capsule?
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Transparent membrane that maintains the organ shape.
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What is the adipose capsule?
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Helps protect the kidney from trauma (nephroptosis)
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What is the renal fascia?
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Dense, irregular connective tissue that holds the kidneys against the back body wall.
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What wastes and foreign substances are secreted from the kidneys?
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ammonia, urea, bilirubin, creatinine, uric acid, toxins, and drugs.
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What enzyme is secreted by the kidney to regulate blood pressure?
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renin
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What is the parenchyma of the kidney?
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(functional part) renal cortex and renal medulla.
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What is the path of urine drainage?
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papillary duct in the renal pyramid, minor calyx, major calyx, renal pelvis, ureter, urinary bladder, urethra
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What are the names of the capillary beds in the kidneys?
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glomerular capillaries
peritubular capillaries |
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What is the function of the glomerular capillaries?
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It is where filtration of blood occurs. The vaso constriction and vasodilation of afferent and efferent aterioles produces large changes in renal filtration.
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What is the function of peritubular capillaries?
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To carry away reabsorbed substances from the filtrate.
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What does the vasa recta do?
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Supplies nutrients to the medulla without disrupting its osmolarity
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What is the order of blood flow from the renal artery to vein?
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Renal artery, segmental arteries, interlobar arteries, arcuate arteries, interlobular arteries, afferent arterioles, glomerular capillaries, efferent arterioles, peritubular capillaries and/or vasa recta, interlobular veins, arcuate veins, interlobar veins, segmental veins, renal vein
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Glomerular capillaries are formed between what 2 arterioles?
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afferent and efferent arterioles.
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Efferent arterioles give rise to what?
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peritubular capillaries and vasa recta.
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A nephron is composed of what?
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A renal corpuscle, renal tubule, and collecting ducts and papillary ducts.
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What happens at the renal corpuscle?
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It is the site of plasma filtration.
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The glomerular capsule is also known as what and does what?
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Bowman's capsule: a double walled epithelial cup that collects filtrate.
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What makes up the renal tubule?
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Proximal convoluted tubule, loop of Henle, distal convoluted tubule
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What are the two types of nephrons?
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Cortical and Juxtamedullary
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Describe a cortical nephron.
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Mostly in the renal cortex
Short loop of Henlethat lies mostly in the cortex and dips only into the outer protion of the renal medulla The loop of Henle receives blood from the peritubular capillaries. |
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Describe a juxtamedullary nephron.
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lies deep in the cortex close to the medulla
has long loop of Henle The ascending limb of the loop of Henle has thin and thick portions The blood supply is from the peritubular capillaries and vasa recta |
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What is the flow of fluid through a cortical nephron?
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Glomerular (Bowman's) capsule, proximal convoluted tubules, descending limb of loop of Henle, ascending limb of loop of Henle, distal convoluted tubule, collecting duct
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What is the flow of fluid through a juxtamedullary nephron?
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Glomerular (Bowman's) capsule, proximal convoluted tubules, descending limb of loop of Henle, thin ascending limb of loop of Henle, thick ascending limb of loop of Henle,distal convoluted tubule, collecting duct
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What cells line the proximal convoluted tubule?
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simple cuboidal with brush border of microvilli
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What type of cell lines the descending limb of the loop of Henle and the thin portion of the ascending limb?
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simple squamous
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What cells line the ascending limb of the loop of Henle?
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simple cuboidal to low columnar
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What cells line the distal convoluted tubule and collecting ducts?
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Simple cuboidal: principal and intercalated
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What is unique for principal cells?
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They have receptors for ADH and aldosterone
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What is unique of intercalated cells?
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They have microvilli that control blood pH
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The renal corpuscle is made of what?
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the glomerulus and the Bowman's capsule
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What is the macula densa?
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The thickened part of the asending limb.
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Juxtaglomerular cells are modified ____ cells in the arteriole?
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muscle
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The filtration barrier separating blood from the space in the Bowman's capsule consists of?
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fenestrated endothelium, basal lamina, and slit membranes that cover the filtration slits
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What are the three types of capillaries?
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continuous; found in skeletal and smooth muscle, connective tissue and lungs
fenestrated; found in the kidneys, SI, choroid plexuses ciliary process and endocrine glands sinussoids; found in liver, bone marrow, spleen, anterior pituitary, parathyroid gland |
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The number of nephrons increased, decreases or stays the same throughout life?
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stays the same
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What prevents backflow of urine from the from the bladder into the ureters?
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physiological valves
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The flow of urine is due to what?
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peristaltic contractions
gravity and hydrostatic pressure |
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What is the micturition reflex?
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stretching of the urinary bladder stimulates reflex causing the bladder to contract, inhibiting urinary sphincters
Higher brain centers can stimulate or inhibit reflex |
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What is the muscularis part of the urinary bladder known as?
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detrusor muscle
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Does parasympathetic or sympathetic fibers carry the signals for micturition?
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parasympathetic
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What are the 3 movements in the formation of urine?
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glomerulaer filtration
tubular reabsorpton tubular excretion |
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What is the most important function of the nephron?
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tubular secretion
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What are the reabsorption routes?
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paracellular
transcellular |
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What is paracellular reabsorption?
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50% of the reabsorbed material moves between cells by diffusion in some parts of the tubule
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What is transcellular reabsorption?
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material that moves through both the apical and basal membranes of the tubule cell by active transport
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In the basolateral membrane Na is moved how?
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Na/K ATPase pumps sodium from the tubule cell cytosol
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How is water reabsorbed?
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osmosis
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What is obligatory water reabsorption?
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occurs when water is "obliged" to follow the solutes being reabsorbed
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What is facultative water reabsorption?
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it occurs in the collecting ducts under the control of ADH
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What is glucosuria?
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When glucose remains in the urine
When renal symporters can not reabsorb glucose fast enough if blood glucose level is above 200 mg/mL |
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What is a common cause of glucosuria?
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diabetes mellitis because insulin activity is deficient and blood sugar is so high
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What are the Na transporters in the 1st half of the PCT?
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Na/K ATPase
Na/H antiporters Na/various substances symporters |
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What substances are completely reabsorbed in the 1st half of the PCT?
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Glucose, aa, lactate, citrate, phosphate, water-solublle vitamins and other nutrients
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Antiporters in the PCT reabsorb and secrete what?
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reabsorb HCO3 into peritubular capillaries
Secrete H+ into fluid in tubule lumen |
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What stimulates the Na/H pumps resulting in HCO3 reabsorption?
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Angiotensin II
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In the 2nd half of the PCT what is produced by symporters and antiporters and what does this cause?
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electrochemical gradients
passive reabsorption of other solutes |
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What is passively diffused into the peritubular capillaries of the 2nd half of the PCT?
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Cl, K, Ca, Mg and urea
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What promotes osmosis in the PCT?
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Aquaporin 1 channels
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Where is ammonia NH3, and urea filtered and secreted?
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filtered: glomerus
secreted: PCT |
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PCT cells _____ _____ in a process that generates both NH3 and new HCO3.
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deaminate glutamine
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The thin descending and thin ascending limbs of the loop of Henle are permeable to what?
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Na, Cl, Urea, water
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The permeability and movement of solutes in/out of the thin limbs is what type of process?
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passive
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In the thick portion of the acsending limb of the loop of Henle what type of symporter is present?
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Na/K/2Cl symporter is responsible for about 25% of the filtered Na that is reabsorbed here
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What happens to the K that is absorbed in the thick portion of the ascending limb of the loop of Henle?
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After it is absorbed it is leaked back out through K channels
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What can be reabsorbed in the thick portion of the acsending limb of the loop of Henle ?
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Na,K, Ca, Mg, Cl
NOT WATER |
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What is removed in the DCT?
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Na, Cl, Ca
NOT WATER |
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What type of symporters are present in the DCT?
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Na/Cl
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What stimulates the absorption of Ca in the DCT?
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PTH (parathyroid hormone)
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In the collecting ducts what do principle cells do?
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reabsorb Na
secrete K |
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In the collecting ducts what do intercalated cells do?
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reabsorb K and HCO3
secrete H |
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How does Na enter the principal cells?
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leakage channels
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What does aldosterone do to principal cells?
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increases Na and water reabsorption and K secretion
stimulates the synthesis of new pumps and channels |
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What causes increased Na and water reabsorption and K secretion by the principal cells?
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Aldosterone
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Intercalated cells use what to secrete H+ against a concentration gradient?
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proton pumps (H+ATPases)
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Intercalated cells use what to move bicarbonate ions into the blood?
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Cl/HCO3 antiporters
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Where is ADH secreted?
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posterior pituitary
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What does ADH do?
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increases water permeability in the DCT and collecting ducts
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Where is aldosterone produced?
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adrenal cortex
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What does aldosterone affect?
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Na and Cl transport in nephron and collecting ducts
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Where is renin produced?
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kidneys
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What does renin do?
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causes production of angiotensin II
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Where is ANP produced?
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By the heart when blood pressure increases
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What does ANP do?
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inhibits ADH production
reduces ability of the kidney to concentrate urine |
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In urine production what happens in the PCT?
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Na and other substancesremoved
Water follows passively Filtrate volume reduces |
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In urine production what happens in the descending limb of the loop of Henle?
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Water exits passively, solutes enter making filtrate hyperosmotic.
Filtrate volume is reduced by 15% |
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In urine production what happens in the ascending limb of the loop of Henle?
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Ca, Cl, K are transported out of filtrate
Water remains making the filtrate hyposmotic |
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In urine production what happens in the DCT and the collecting ducts?
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Water movement out is regulated by ADH
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How does angiotensin II and aldosterone affect Na, Cl, and water reabsoption and K secretion in the tubules?
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Decreases GFR by vasoconstricting afferent arteriole
Enhances absorption of Na by activating Na/H antiporters in the PCT Promotes aldosterone production which causes principle cells to reabsorb more Na l |
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How does Atrial Natriuretic Peptide affect Na, Cl, and water reabsoption and K secretion in the tubules?
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Inhibits reabsorption of Na and water in PCT
Suppresses secretion of aldosterone and ADH Increases excretion of Na which increases urine output |
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What does ADH do to principal cells?
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increases water permeailityof the pricnipal cells so regulates facultative water reabsorption
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What effect does ADH ahve on aquaporin-2 channels?
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stimulates the insertion of channels into the membrane
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When water is not available what happens to the urine concentration?
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Kideney produce small amout of concentrated urine
Removes waste and prevents rapid dehydration Obligatory urine volume |
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What is the obligatory urine volume?
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0.5blitter/day: the maximal concentrating ability of the kidney
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What are the requirements for excreting concentrated urine?
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High levels of ADH
A high osmolarity in the renal medulla |
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What are the main factors contributing to solute buildup in the renal medulla?
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Active transport of Na out of thick portion of the ascending loop of Henle
Active transport of ions out of collecting ducts Passive diffusion of large amounts of urea from collecting ducts into medullary interstitium Little or no diffusion of water out of the DCT and collecting ducts |
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Is the descending limb permeable to water?
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yes very
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Is the ascending limb permeable to water?
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No
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What causes a buildup of urea in the renal medulla?
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Urea recycling
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Dilute urine and frequent urination is common signs of what?
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diabetes insipidus
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What is a diuretic and give some examples.
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Substances that slow renal reabsorption of water and causes diuresis ( increased urine flow rate).
Caffeine, inhibits Na reabsorption Alcohol inhibits secretion of ADH |
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What are 2 tests uses to evaluate kidney function?
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urinalysis, blood tests
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In a urinalysis, the urine is expected to be free of what?
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proteins
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What is a BUN test and what does it measure for?
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Blood Urea Nitrogen test
measures urea in the blood |
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What is plasma creatinine a sign of?
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skeletal muscle breakdown
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What is dialysis therapy?
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When kidney function is severly impaired and blood must be cleamsed artificially
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What is plasma clearance?
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volume of plasma cleared of specific substance each minute
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What is tubular load?
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Total amount of substance that passes through filtration membrane into nephrons each minute
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What is the renal clearance of a substance?
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the volume of plasma that is completely cleared of the substance per unit time
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what is the gold standard of glomerular filtration rate (GFR)
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insulin
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What does the term threshold mean in reference to glucose?
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the filtered load of glucose at which glucose first begins to be excreted in the urine
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What is the transport maximum in reference to glucose reabsorption?
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maximum rate at which glucose can be reabsorbed from the tubules
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What is tubular maximum?
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maximum rate at which a substance can be actively absorbed, each substance has its own max
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What is PAH?
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ρ-aminohippurate: it is almost 90% cleared by glomerular filtration and tubular secretion: it is used to determine renal plasma flow
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What are the three basic processes of the nephrons and collecting ducts?
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glomerular filtration
tubular reabsorption tubular secretion |
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What is glomerular filtration?
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a portion of the blood plasma is filtered into the kidney; some waste such as urea, creatine, uric acid and urates are poorly reabsorbed
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What is tubular reabsorption?
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(quantitatively more important) water and useful substances (electrolytes, aa, glu) are reabsorbed into the blood
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What is tubular secretion?
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usually the lowest rate relative to filtration and reabsorption
wastes are removed from blood and secreted into urine |
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What is the rate of excretion of any substance?
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rate of filtration, plus its rate of secretion, minus its rate of reabsorption
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What produces glomerular filtrate?
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blood pressure
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How many gallons per day are reabsorbed leaving how many quarts of urine?
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48 gallons/day
1-2qt/day |
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What are the layers that make up the filtration membrane of the glomerular?
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fenestrated endothelium
basal lamina slit membrane |
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What does the fenestrated endothelium stop from passing through?
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All cells and platelets
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What does the basal lamina stop from passing through?
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large plasma proteins
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The slit membrane prevents what from passing through?
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medium sized proteins, not small ones
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Glomerular filtration depends on what?
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size, shape, electrical charge
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What substances are freely filterable?
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water, sodium, glucose, insulin
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What are the 4 forces in the net filtration pressure (NFP)?
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Glomerular capillary hydrostatic pressure (promotes filtration)
Capsular (Bowman's) hydrostatic pressure (opposes filtration) Blood capillary colloidal osmotic pressure (opposes filtration Capsular colloidal osmotic pressure (promotes filtration) |
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What is the renal blood flow (RBF)?
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pressure of the renal artery - pressure of the renal vein
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What is the filtration fraction?
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The fraction of blood plasma that tis filtered by the glomerular capillaries.
Filtration fraction = GFR/renal plasma flow |
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What are the controls of glomerular filtration and renal blood flow?
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autoregulation
neuronal hormonal |
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What is the myogenic mechanism in the renal autoregulation of GFR?
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it detects changes in the arterial pressures
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What is the tubuloglomerular feedback in the autoregulation of GFR?
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detects changes in NaCl in tubular fluid
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Neural regulation of the GFR by the sympathetic system causes more what with increased stimulation?
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vasoconstriction, decreasing
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What does ANP do to GFR?
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increases
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What does angiotensin II do to GFR?
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reduces
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What is renin release stimulated by?
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decrease in BP
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epinephrine and nor epinephrine cause what?
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vasoconstiction
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What does NO do?
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decreases renal vascular resistance ( increases GFP)
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What do prostaglandins do to GFP?
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increase
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What is endothelin?
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a powerful vasoconstrictor
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What hormones decrease the GFR?
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norepinephrine, epinephrine, endothelin
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What hormones increase the GFR?
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endothelial-derived nitric oxide, prostaglandins
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Where are the intracellular fluids?
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inside the cells body, cytoplasm, nucleoplasma etc. about 40% of total body weight
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Where are the extracellular fluids?
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all the fluids outside the cell about 20% of total body weight
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Where are the only 2 places for exchange of fluids between compartments?
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cell membranes
capillaries |
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What are the primary regulator of water excretion?
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kidneys
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What are the sources of water?
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ingestion
cellular metabolism |
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What are the routes of water loss?
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urine
evaporation feces |
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Thirst is what?
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the main regulator of water gain
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Where is the thirst center located?
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hypothalamus
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What increases thirst?
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increased osmolarity, angiotensin II
decreased blood volume and pressure |
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What decreases thirst?
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Decreased osmolarity, angiotensin II
Increased blood |
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What major hormones help to regulate water and solute loss.
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RAA, ADH, ANP
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What do angiotensin II and aldosterone do?
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promote reabsorption of Na and Cl and an increase in fluid volume
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What does ANP do?
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slows release of renin
increases filtration rate reduces water and Na reabsorption decreases secretion of aldosterone |
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Increased ECF results in what?
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decreased aldosterone and ADH secretion
Decreased sympathetic stimulation Increased ANH secretion |
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Decreased ECF results in what?
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Increased aldosterone and ADH secretion
Increased sympathetic stimulation Decreased ANH secretion |
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Increased osmolarity triggers what?
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thirst and ADH secretion
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Decreased osmolarity inhibits what?
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thirst and ADH secretion
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What are the functions of electrolytes?
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control osmosis between fuild compartments
Help maintain acid base balance Carry electric current cofactors needed for enzymatic activity |
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Extracellular fluid contains what?
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Na Cl
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Intracellular fluid contains what?
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K and phosphates (HPO4)
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What is the most abundant extracellular ion?
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Na
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What causes edema?
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sodium retention which causs water retention
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What causes hypovolemia?
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Excessive loss of sodium causes excessive loss of water
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What are the perdominate anions in ECF?
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Chloride ions
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What is the most abundant cation in the intracellular fluid?
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K
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What does low plasma K cause in neuromuscular activity?
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muscle weakness, paralysis, intestinal indigestion, peripheral vasodialation, respiratory failure
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What does high plasma K cause in neuromuscular activity?
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increased muscle excitability, later, muscle weakness and paralysis
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What does low plasma K cause in cardiac activity?
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slow pacemaker activity, arrhythmias
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What does high plasma K cause in cardiac activity?
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conduction disturbances, ventricular arrhythmias, ventricular fibrillation
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What does low plasma K cause in vascular resistance?
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vasoconstriction
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What does high plasma K cause in vascular resistance?
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vasodilation
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What is bicarbonates role in plasma?
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major buffer
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What is the most abundant mineral in the body?
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Ca
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