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108 Cards in this Set
- Front
- Back
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What is the functional unit of the kidney
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the nephron
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The glomerulus has a glomerular capillary network and those capillaries are surrounded by
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Bowman's Capsule
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Where does filtration occur?
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glomerulus
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Where is the only capillary bed btw two arteries? control bp
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glomerulus
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What makes up 85 % of nephrons
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cortical nephrons
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What is 15% of nephrons?
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Juxtamudullary
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What are the functions of the kidney
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homeostatic environment, endocrine fx, gluconeogenesis
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What is homeostatic cellular environment
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-balance water & solutes
-excrete metabolic waste -conserve nutrients -acid base regulation |
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Endocrine fx of the kidney
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BP control, RBC production,
Ca+ balance VItamin D |
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What is renal clearance?
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The volume of plasma completely cleared of a substance by the kidneys per unit time or the ratio of urinary excretion to plasma concentration
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What is the formula for Renal Clearance
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C=[U] * V/[P]
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What is C
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clearance
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What is [U]
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urine concentration of substance X
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What is [P]
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plasma concentration of substance X
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WHat is V
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urine flow rate per minute
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Substances will have a high renal clearance when
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they are both filtered and secreted
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Inulin (a fructose polymer) renal clearance=
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glomerular filtration rate....bc it is filtered but neither reabsorbed or secreted.
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Inulin is considered
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the glomerular marker
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Clearance ratio is
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the fractional clearance of substance X
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Clearance ratio=
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C(of x)/C(of inulin)
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If clearance ration= 1.0 then
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the clearance of x equals the clearance of inulin and also must be a glomerular marker
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If clearance ration < 1.0 then
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the clearance of x is LOWER than the clearance of inulin and either the substance is filtered and it is filtered and subsequently reabsorbed
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If clearance ratio > 1.0 then
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the clearance of x is higher than the clearance of inulin and the substance is filtered and secreted
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The kidney takes what percentage of oxygenated blood?
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25%
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Renal flow is
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inversely proportional to resistance
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what does the SNS use to cause vasoconstriction in both types of arterioles?
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catecholamines
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What is the most potent vasocontrictor and the efferent arteriole is more sensitive to it?
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Angiotension II
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What causes the vasodilation of the renal arterioles?
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prostaglandins
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what in low doses also has a vasodilatory effect?
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dopamine
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renal blood flow remains constant over values of arerial pressure
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80-200 mm Hg
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Renal blood flow will decrease when MAP <
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80
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Myogenic hypothesis
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is the stretching of vessels due to increased pressure. Stretching of vessels causes Ca++ influx which causes contraction in the smooth muscle of the blood vessel and therefore increased resistance
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Tubuloglomerular feedback states that
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when renal arterial pressure inc then both renal blood flow and glomerular filtration rate inc.
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When GFR is inc the macula densa within the juxtaglomerular appartus senses this inc and scretes
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a substance that causes vasoconstriction of the afferent arterioles and dec the flow
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Hormonal regulation -
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renin axis, ADH/AVP, ANP
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Neurological regulation=
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all sympathetic innervation no PNS
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Norepinephrine is catecholamine involved via
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baroreceptors, chemoreceptors and stretch receptors
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Glomerular filtration is where
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urine formation begins
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Starling forces are responsible for
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filtration across the glomerulus
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Hydrostatic pressure of the capillary favors
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filtration
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Hydrostatic pressure in Bowman’s space
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opposes filtration
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oncotic pressure in glomerular capillaries
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also oppose filtration
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negative charge on the glomerular barrier which adds
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an electrostatic component to filtration. If there is negative charge then obviously positively charged solutes will be attracted to it.
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The net ultrafiltrate pressure
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pressure is the driving force behind filtration and always favors filtration i.e. movement of fluid out of the capillary. The greater the net pressure, the higher the rate of glomerular filtration.
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Creatinine Clearance
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the clinical measurement of GFR (though it is slightly higher).
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Blood urea nitrogen and serum creatinine concentration are both used to estimate GFR because
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both are filtered across the capillaries. If BUN and Creatinine are not adequately filtered than their levels go up.
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Tubular transport processes consist
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of reabsorption, secretion and filtration. These three together = excretion (Figure 6-12).
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Glucose reabsorption is an example
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of a tubular transport process.
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Glucose is filtered through the capillary and then reabsorbed by the
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epithelial cells in the proximal tubule
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Two step process:
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Na+-glucose cotransport and facilitated glucose transport
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Glucose has a transport maximum because
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there is a limited number of glucose transporters
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Urea reabsorption occurs passively
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i.e. diffusion as opposed to glucose which is carrier mediated
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PAH is an example of secretion. It is filtered across the capillary and secreted
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secreted into the tubular fluid. Here PAH excretion is the sum of filtration + secretion.
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Sodium Balance
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is the most important function of the kidney
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Positive Na+ balance =
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ECF volume increase = edema.
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Na+ is freely filtered
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across the glomerular capillary
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Potassium balance is essential for the normal fx of
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excitable tissue
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Water balance or body fluid osmolarity is maintained at
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290 mOsm/Lby osmoregulation
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Isosmotic urine=
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blood osmolarity,
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hyperosmotic urine=
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higher than blood osmolarity
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concentration of urine occurs via
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ADH
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ADH has three actions on the renal tubules
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1. inc water permeability of the principal cells of the late distal tubule and collecting ducts
2. increases activity of K/Na/Cl transport system enhancing countercurrent multiplication and the corticopapillary osmotic gradient 3. ) increases urea permeability which enhances urea recycling and the size of the corticopapillary osmotic gradient. |
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Hyperosmotic Urine happens when circulating levels of ADH
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are high (this is concentrated urine because the body is holding onto water so therefore urine will be concentrated as in SIADH or water deprivation).
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Hyposmotic Urine happens when circulating levels of ADH
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are low or when ADH is ineffective (this is dilute urine because the body is diuresising all of its fluid). Understand central DI v. nephrogenic DI.
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conducting zone
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brings air in and out of the lungs
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respiratory zone
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where gas exchange occurs
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What i the main conducting airway?
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trachea
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Airways are lined with
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smooth muscle that are innervated by both PNS and SNS
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PNS=
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constriction of airways via muscarinic receptors
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SNS-
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dilation of airways via B2 receptors on the bronchioles....
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Why dont we give Beta blockers to asthmatics?
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restrict airway dilation
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Gas exchange occurs in
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respiratory bronchioles, alveolar ducts and the alveolar sacs
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HOw many alveoli in each lung
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300
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Alveolar walls are thin and have large surface area which allows for
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quick and easy diffusion of oxygen and CO2.
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Surfactant is produced by which type of alveolar cells?
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2
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Pulmonary blood flow =
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cardiac output of the right heart
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Bronchila circulation is the
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blood supply to the conducting airways and does not participate in gas exchange
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Tidal volume (TV)
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the volume of air that fills the alveoli plus the volume of air that fills the airways (500 mL)
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Inspiratory reserve volume (IRV)
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additional volume that can be inspired about tidal volume (3000 mL)
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expiratory reserve volume (ERV)
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additional volume that can be expired below tidal volume (1200)
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Residual volume (RV)
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volume of gas remaining in the lungs after a maximal forced expiration...approx 1200
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Inspiratoyr capacity (IC)
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TV+IRV=3500mL
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functional residual capacity
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ERV+ RV=2400mL; volume of air in the ungs left over after a normal tidal volume is expired
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vital capacity(VC_=
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IC+ERV=4700mL; volume to be expired after maximal inspiration; this increases with body size, male gender, conditioning and decreases with age
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Total lung capacity(TLC)
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VC+RV=5900mL
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Anatomic dead space
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volume of the conducting airways=150 mL
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Physiologic dead space
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anatomic+functional amount of dead space of each alveoli
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Minute ventilation=
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VT*Breaths/min
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Alveolar ventilation=
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(VT-VD)*Breaths/min; VA alveolar ventilation, VT tidal volume, VD physiologic dead space
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the alveolar ventilation equation is the
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fundamental relationship of respiratory physiology
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Alveolar ventilation=
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alveolar PCO2
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b. If CO2 production is constant than PACO2 is determined by
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alveolar ventialtion
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If alveolar ventialation increase then PaCO2
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decreases
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alveolar gas equation predicts
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alveolar PO2 based on the alveolar PCO2
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compliance=
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distensibility
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compliance of the lungs and chest wall is inversely correlated to
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elastance
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so the thicker the lung tissure the greater
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the elastance and snap back and the less compliance
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More negative pressure=
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more inflation with air
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The difference in the shape of the curves for compliance of inspiration and expiration is
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due to the difference in surface tension of the lung during those times
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Resting volume of the chest wall and lung system is the
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functional residual capacity
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Law of LaPlace
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Large alveolus require little pressure to keep it open but small alveolus require a larger amount of pressure to keep it open.
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a. Surfactant is a phospholipid that helps keep the alveolus
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from collapsing on themselves.
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Poiseuille’s Law
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resistance increases then flow decreases. They are directly proportional to one and another.
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a. Changes in diameter of the airways alters
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resistance and airflow
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a. Diffusion limited amount of gas transported is limited by the diffusion process
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here the partial pressure gradient is maintained.
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b. Perfusion limited amount of gas transported is limited by the blood flow or perfusion through the pulmonary capillaries.
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Here the partial pressure gradient is not maintained.
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c. The partial pressure gradient is the pressure across
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the alveolus and capillary blood along the length of the capillary.
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Brain stem control of breathing
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medullary, apneustic, pneumotaxic
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