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Chapter 13
Renal
66
Physiology
Undergraduate 2
04/12/2011

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Term
What are the major functions of the kidney?
Definition
Excretory, Regulatory, and Metabolic
Term
What are some examples of the Excretory function of kidneys?
Definition
Waste-metabolic and removal of foreign chemicals
Term
What are some examples of the Regulatory function of kidneys? 
Definition
pH, RBC production, blood pressure, H2O, ion balance
Term
What are some examples of the Metabolic function of kidneys?
Definition

-Gluconeogenesis- kidney glucose from amino acids and other precursors and release it into blood.

-Production of hormones/enzymes: erythropoietin controls erythrocytes production, renin, enzymes control formation angiotensin, influence blood pressure and sodium, vitamin D

Term
Name the major parts of a nephron.
Definition
Glomerulus, proximal tubule, Loop of Henle, Distal convoluted tubule, and collecting duct
Term
What processes are carried out at the Glomerulus?
Definition
Forms ultrafiltrates of plasma, controlled by starlings forces
Term
What processes are carried out by the proximal tubule?
Definition
bulk reabsorption of solutes and water, secretion of solutes (except potassium), and organic acids and bases, controlled by active transport of solute with passive water reabsorption and parathyroid hormones inhibit phosphate reabsorption
Term
What processes are carried out by the Loop of Henle?
Definition

Establishes medullary osmotic gradient, secretion of urea

-Desending limb- bulk reabsorption of water controlled by passive water reabsorption

- Ascending limb- reabsorption of NaCl, controlled by active transport.

Term
What is the processes carried out by the Distal convoluted tubule?
Definition
Fine-tuning of reabsorption/secretion of small quantity of solute remaining, controlled by aldosterone and by parathyroid hormone
Term
What processes are carried out by the collecting ducts?
Definition
Fine tuning of water reabsorption, reabsorption of urea, controlled by vasopressin increasing passive reabsorption of water.
Term
What substances are produced by the kidney?
Definition
Hormones and enzymes such as erythropoietin, 1,2-5-dihydroxyvitamin D and renin
Term
What are the hormonal controls on renal activity?
Definition
Angiotensinogen is converted to angiotensin I by renin which is converted to angiotensin II which increases plasma aldosterone and causes retention of salt and water. Others are listed in 2.
Term
Define Glomerular filtration rate.
Definition
Volume of fluid filtered from renal glomerular capillaries into Bowman;s capsule per unit of time.
Term
Define filtered load.
Definition
amount of any substance filtered from renal glomerular capillaries into Bowman's capsule
Term
Define renal clearance.
Definition
volume of plasma from which a solute must be completely removed to supply what is being lost in the urine per unit of time. 
Term
Define transport maximum.
Definition
The maximal amount of solute that can be reabsorbed per unit of time. At this maximum the transport process becomes saturated 
Term
Define micturition.
Definition
urination
Term
Define excretion.
Definition
Elimination of a substance from the body
Term
Define secretion.
Definition
Elaboration and release of organic molecules, ions and H2O by cells in response to specific stimuli.
Term
Define reabsorption.
Definition
amount retaken up and not sent to urinary tubule for excretion.
Term
Define renal threshold.
Definition
The minimum plasma concentration of solute which exceed the transport maximum for the reabsorption of that solute.
Term
What is required of a solute employed to measure Glomerular filtration rate?
Definition

Cant be protein bound, need it to be permeable.

Has to be filtered, but not reabsorbed, secreted or metabolized.

Creatine is used to approximate the GFR but undergoes a small amount of secretion so is not ideal

Term
How can it be determined if a solute undergoes tubular reabsorption?
Definition
Amount reabsorbed the difference between the amount entered and amount excreted. you know GFR, and know how much enter Bowman's capsule you can measure amount excreted from urine.
Term
How can it be determined if a solute undergoes tubular excretion?
Definition
you know GFR, and know how much enter Bowman's capsule you can measure amount excreted from urine.
Term
How does the glomerulus differ from the other, more typically capillary beds?
Definition
THe main difference is in the intracapillary hydrostatic pressure.
Term
Where does the kidney reabsorb most of the solutes that are reabsorbed? The fine-tuning reabsorption?
Definition
The proximal tubule for bulk and the fine tuning is in the distal tubule and cortical collecting duct.
Term
Where does the kidney reabsorb most of the water? The fine tuning of water reabsorption?
Definition
Bulk is in the descending limb of the Loop of Henle and the fine tuning is in the cortical and medullary collecting ducts.
Term
How many urethral sphincter muscles are there?
Definition
3: Detrusor, Internal urethral sphincter, and Urethral sphincter.
Term
How is the Detrusor muscle innervated?
Definition
Parasympathetic causes contraction, inhibition during filing and simulated during micturition.
Term
How is the Internal urethral sphincter innervated?
Definition
sympathetic causes contraction, stimulated during filling and inhibited during micturition.
Term
How is the urethral sphincter innervated?
Definition
somatic motor causes contraction, stimulated during filing and inhibited during micturition.
Term
Explain the reflex arc for micturition.
Definition

The Liver makes angiotensinogen, kidney produced renin which controls conversion of angioteninogen to angiotensin I which is converted by an enzyme to angiotensin II which affects the adrenal cortex to produce aldosterone which affects kidney to lead to salt and H2O retention.

Decreased vasopressin secretion in posterior pituitary leads to decreased reabsorption of water in collection ducts and excretion of water in urine.

Sodium excretion is controlled by atrial natriuretic peptide

Term
What are the 4-5 ways body loses water and which one is used to regulate body's water balance?
Definition
Insensible loss (skin and lungs), sweat, feces, and urine (regulated amount of water in body)
Term
What are the 3 routes by which sodium is lost? Which on is to regulate the body's sodium content?
Definition
Sweat, feces, urine (the regulator)
Term
How does the kidney handle sodium ion?
Definition
66% reabsorption in proximal tubule, 26% in Loop of Henley, and on .6% is excreted
Term
How does the kidney handle the Potassium ion?
Definition
80% reabsorption in proximal tubule, some reabsorbed in Loop of Henle and 15% is excreted.
Term
How does the kidney handle Water?
Definition
65% is reabsorbed in proximal tubule, 10% in Loop of henle, and .6% excreted
Term
How does the kidney handle glucose?
Definition
All glucose is reabsorbed in proximal tubule.
Term
What is renin and where is it produced?
Definition
Renin is an exzyme secreted by the juxtaglomerular cells of the juxtaglomerular apparatuses in the kidneys.
Term
What are the three major controls on renin's secretion?
Definition

Renal sympathetic nerves

Intravenal baroreceptors 

Macula densa

Term
How does the autonomic nervous system influence renin secretion from the kidney? (Division and receptor)
Definition
Increased renin secretion by sympathetic via beta-one receptor.
Term
What are the two hormones controlling the body's sodium level?
Definition

Major control of tubular sodium reabsorption is adrenal cortical hormone aldosterone, which stimulates reabsorption in the cortical collecting ducts.

Atrial natriuretic peptide- cells in the cardiac atria synthesize and secrete ANP which inhibits sodium reabsorption and aldosterone and is controlled by atrial distension.

Term
How can the body control water loss without also controlling sodium loss?
Definition
ADH opens aquaporins allowing water through but not sodium via the countercurrent multiplier.
Term
What are the major consequences of hypokaiemia?
Definition
Decreased extracellular potassium content. Can cause abnormal rhythms of heart and abnormalities of skeletal muscle contraction
Term
What are the major consequences of hyperkalemia?
Definition
Increased extracellular potassium content.Can cause abnormal rhythms of heart and abnormalities of skeletal muscle contraction.
Term
What is the mechanism by which the body regulates its potassium level?
Definition
Cortical collecting ducts can secrete potassium when high potassium diet. Also Aldosterone contorls potassium balance
Term
What are the three systems which are balanced to regulate plasma calcium ion concentration? What hormone controls each of these?
Definition
 storage (Bone), Reabsorption (GI tract), and excretion (renal).  Regulated by parathyroid hormone.
Term
What vitamin does the parathyroid hormone regulate? And what does the vitamin do?
Definition
Regulates Vitamin D. Increases calcium and phosphate absorption in GI tract.
Term
How do the kidneys handle calcium?
Definition
Kidney has peoerful mechanism to reabsorb calcium for tubular fluid. 60% of calcium reabsorption in proximal tubule.
Term
What three tissues are involved in the synthesis of vitamin D?
Definition
Tissues of skin, liver, kidneys.
Term
Is the normal American adult eating a normal American diet under an acid or an alkali load?
Definition
Alkali load
Term
How Acidic can urine be?
Definition
The lowest can be about 4.4
Term
Is the 4.4 acid enough to eliminate all of the hydrogen ion that needs to be eliminated?`
Definition
No, the other two mechanisms are utilized to help eliminate the hydrogen ion.
Term
What are the two mechanisms by which the kidneys can eliminate additional hydrogen ion?
Definition
The mechanisms are generation of ammonia and regulation of bicarbonate to neutralize high pH
Term
What is the carbonate buffer equation?
Definition
CO2 + H2O <->H2CO3 <-> HCO3- + H+
Term
What is the effect of carbonic anhydrase on these reactions?
Definition
Carbonic anhydrase catalyzes the process of bicarbonate being reabsorbed when H+ ions are secreted.
Term
What is the mechanism by which the kidneys conserve the bicarbonate that has been filtered at the glomerulus?
Definition
Bicarbonate is reabsorbed by H+ ATPase pumps- primarily H+/K+ ATPase pumps
Term
How does the kidney generate "new" bicarbonate?
Definition

New bicarbonate can be generated when extra H+ ions combine with filtered non bicarbonate buffer and bicarbonate is generated within the tubular cell by the carbonic anhydrase reaction and entering plasma constitutes net gain of bicarbonate.

 

Term
From what reactant does the kidney generate ammonium ion?
Definition
The tubule cells take glutamine amino acids
Term
What controls the rate of ammonium production?
Definition
It is stimulated by acidic intracellular pH
Term
What effect does aldosterone have on the renal excretion of hydrogen ion?
Definition
Aldosterone stimulates hydrogen ion secretion in the collection duct and of increased excretion of potassium ion
Term
How do plasma membrane concentration of hydrogen ion, carbon dioxide, and bicarbonate change in Metabolic acidosis and alkalosis?
Definition

Acidosis- decreased bicarbonate, increased H+ decreased CO2

Alkalosis- Decreased H+, increased bicarbonate, increased CO2

Term
How do plasma membrane concentrations of hydrogen ion, carbon dioxide, and bicarbonate change in respiratory acidosis and alkalosis?
Definition

acidosis- Increases CO2, H+, and bicarbonate

alkalosis- decrease CO2, H+, and bicarbonate.

Term
Where in the kidney is carbonic anhydrase found and what is its function?
Definition
Found in the proximal tubule and its function is to catalyze the reaction of water and carbon dioxide to form H2CO3 which dissociates into H+ ion and bicarbonate ion.
Term
How does the respiratory system respond to acidosis and alkalosis?
Definition
Based on changes in carbon dioxide.
Term
How do the kidneys respond to Acidosis and alkalosis?
Definition
based on Changes in bicarbonate.
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