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Systems test 3
test 3
158
Physiology
Professional
03/22/2008

Additional Physiology Flashcards

 


 

Cards

Term
What is Fick's Law of Diffusion?
Definition
the diffusion of a gas is directly proportional to the concentration gradient of the gas and the surface area of the pulmonary caplillary bed available for diffusion
Term
What is the purpose of the cartillagenous rings in the first four generations of airways?
Definition
they are exposed to thoracic pressures, and the rings prevent airway collapse
Term
What is the terminal respiratory unit composed of?
Definition
type I alveolar pneumocytes, interstitial tissue, and capillary endothelial cells
Term
What is Dalton's law?
Definition
the total pressure is the sum of the the partial pressures of the individual gases in the atmosphere
Term
What is the fraction of oxygen in the atmosphere? Of nitrogen?
Definition

21%

79%

 

water vapor and co2 are small enough to be considered 0 

Term
What is the respiratory quotient?
Definition

CO2 production/ O2 consumption

 

normally 0.8 

Term
What is the equation for the alveolar partial pressure of oxygen?
Definition

PAO2=PIO2-PACO2[FIO2+(1-FIO2)/R]

 

PAO2(CO2)= alveolar partial pressure O2 (CO2)

PIO2= inspired partial pressure O2

FIO2=fraction O2 in inspired air

R=respiratory quotient 

 

Term
What is it called when a small amount of venous blood bypasses pulmonary capillaries and enters the arterial circulation without being exposed to alveoli and becoming oxygenated?
Definition
venous admixture
Term
What is the alveolar-arterial gradient? What is a normal value?
Definition

the difference between the calculated PAO2 (alveolar) and the measured PaO2 (arterial)

 

7-10 mmHg 

Term

What is a normal PAO2 at sea level?

 

What is a normal PaO2? 

Definition

100 mm Hg

 

85-95 mm Hg 

Term
What is the normal PaCO2? What is the formula?
Definition

35-45 mm Hg

 

PaCO2= CO2 production x 0.863 / alveolar ventilation 

Term
How much oxygen is dissolved in plasma?
Definition
related to its partial pressure and its solubility constant (0.0031)
Term
When fully saturated, how much oxygen can 1 gram of hemoglobin carry?
Definition
1.34 ml
Term
What two major factors determine the amount of oxygen actually delivered to tissues?
Definition
the arterial oxygen content and the cardiac output
Term
What is the formula for minute ventilation?
Definition
the tidal volume times the frequency of breathing
Term
What is tidal volume?
Definition
the amount of gas inspired each breath
Term
What is the dead space volume?
Definition
the portion of each tidal volume that ventilates only the conducting airways which never reaches the alveoli (about 150 ml)
Term
What is the ratio of FEV1 to FVC (amount expired in one second to the forced vital capacity) a measure of?
Definition
airway obstruction
Term
What is the average alveolar oxygen partial pressure?
Definition
100 mm Hg
Term
What is methemoglobin?
Definition
a hemoglobin with it's iron oxidized by nitriles or sulfonamides and is incapable of binding oxygen
Term
Which way does an increase in temperature shift the hemoglobin curve?
Definition
right (lower affinity)
Term
Which way does an increase in pH shift the hemoglobin curve?
Definition
left (higher affinity)
Term
Which way does an increase in the concentration of 2,3 DPG shift the hemoglobin curve?
Definition
right (lower affinity)
Term
What does Henry's law state?
Definition
as the cells release CO2 and the PCO2 begins to rise, the amount of CO2 dissolved in venous capillary blood increases proportionally and the plasma and erythrocyte CO2 concentrations increase
Term
What is the Hamburger shift?
Definition
moves chloride ion into the erythrocyte in exchange for the bicarbonate
Term
What is the Haldane effect?
Definition
the binding of CO2 in the tissues facilitates the release of O2
Term
What is tidal volume?
Definition
the amount of air inspired with each normal breath
Term
What is the value of a normal tidal volume?
Definition
500 ml
Term
What is minute ventilation?
Definition
the amount of air inspired each minute
Term
What is the expired ventilation?
Definition
the amount of gas exhaled each minute
Term
Why is the minute ventilation slightly greater than the expired ventilation?
Definition
the ratio of carbon dioide production to oxygen consumption is usually less than one (the respiratory quotient, about 0.8)
Term
For each 500 ml air inhaled, about how much remains in the conducting airways and does not take part in gas exchange?
Definition
150 ml
Term
What is physiologic dead space?
Definition
the sum of the anatomic dead space and the alveolar dead space and constitutes all parts of the tidal volume that do not take part in gas exchange.
Term
How do pulmonary and cardiovascular disease result in increased physiologic dead space?
Definition
decrease perfusion to alveoli
Term
What is a pulmonary emboli?
Definition
obstruction of blood flow through pulmonary artery, arterioles and capillaries
Term
What is emphysema?
Definition
destruction of alveolar-capillary membranes.
Term
What is pulmonary fibrosis?
Definition
vascular tissue replaced with fibrous tissue
Term
What is adult respiratory distress syndrome?
Definition
acute inflammation of lungs with diffuse areas of altered perfusion and ventilation
Term
What is the Bohr equation to calculate alveolar volume?
Definition
tidal volume times expired concentration of CO2 = alveolar volume times alveolar concentration of CO2
Term
What must the PaCO2 be for a diagnosis of hyperventilation?
Definition
less than 35 mmHg
Term
What does the PaCO2 need to be for a diagnosis of hypoventilation?
Definition
greater than 45 mmHg
Term
What does the pulmonary circulation protect the systemic circulation from?
Definition
embolization of air, thrombi, amniotic fluid, and fat
Term
What can capillary endothelial cells activate to produce compounds that affect the local circulation, airways and systemic circulation?
Definition
angiotensin I
Term
What can capillary endothelial cells inactivate to produce compounds that affect the local circulation, airways and systemic circulation?
Definition
bradykinin, serotonin, prostaglandins E1, 2 and F2 and NE
Term
What can capillary endothelial cells produce during damage that affect the local circulation, airways and systemic circulation?
Definition
histamine, prostaglandins, and leudotrienes
Term
What percent of the total blood volume is contained in the pulmonary circulation?
Definition
10%
Term
What is the driving pressure or perfusion pressure from the left ventricle to the right atrium?
Definition
100 mmHg
Term
What is the driving or perfusion pressure from the right ventricle to the left atrium?
Definition
10 mmHg
Term
What percent of the lung's weight is blood?
Definition
more than 40%
Term
What are two mechanisms causing a decrease in pulmonary vascular resistance?
Definition
capillary recruitment and capillary distension
Term
What happens to extra-alveolar vessels during inspiration?
Definition
there is a decrease in pleural pressure causing an increase in transmural pressure with increases diameter
Term
What happens to the alveolar capillaries during inspiration?
Definition
the lumen decreases in internal diameter
Term
When is pulmonary vascular resistance the lowest?
Definition
functional residual capacity
Term
What is the increase in resistance at low lung volumes due to?
Definition
compression of extra-alveolar vessels by increases in pleural pressure and decreased traction on the vessels by connective tissue
Term
What is the increase in resistance at high lung volumes due to?
Definition
increased size of alveoli and compression of alveolar capillaries
Term
Name some vasoconstictors
Definition
serotonin, NE, histamine, thromboxane A2, leukotrienes
Term
Name some vasodilators
Definition
adenosine, Ach, PGI2, and isoproterenol and NO
Term
What does global hypoxia cause?
Definition
generalized pulmonary vasoconstriction leading to a significant rise in pulmonary vascular resistance and pulmonary artery pressure
Term
What factors does fluid flux depend on?
Definition
hydrostatic pressure, colloid osmotic pressure, alveolar surface tension, capillary permeability, pulmonary edema
Term
What can increase surface tension?
Definition
damage to type II alveolar pneumocytes decreases surfactant production
Term
What causes decreased colloid osmotic pressure?
Definition
systemic inflammatory syndrome, nephrotic syndrome, liver failure, burns and severe malnutrition
Term
What is Fick's law which describes diffusion of oxygen and CO2 across the alveolar-capillary membrane?
Definition
Vgas= (AxD(P1-P2))/thickness
Term
What is used to measure the diffusion capacity?
Definition
carbon monoxide
Term
What part of the lung recieves the most ventilation?
Definition
the base
Term
In what order does the lung fill?
Definition
sub-apical alveoli, mid-thorax, base
Term
Where is the initial pulmonary lesion of TB?
Definition
in the periphery of the mid-lung fields
Term
Where do TB and fungi grow best?
Definition
apex due to their high oxygen requirements for growth
Term
What is alpha-1-antitrypsin deficiency?
Definition
a metabolic disease where protease inhibitors are deficient. failure to inhibit proteases released by blood born white blood cells leads to destruction of lung parenchyma
Term

What is a v/Q mismatch?
Definition
a mismatching of ventilation and perfusion
Term
What is the distribution of ventilation to the alveolus dependent upon?
Definition
compliance of the alveolus and the resistance of the conducting airway
Term
What are three factors increasing airway resistance?
Definition
bronchiospasm and airway collapse; airway secretions; peribronchial edema or fibrosis
Term
What happens if the V/Q ratio is less than 1?
Definition
will lower the oxygen content and raise the carbon dioxide content of blood coming from units with these ratios
Term
What happens if the V/Q ratio is greater than 1?
Definition
will raise the oxygen content and lower the carbon dioxide content of blood coming from units with these ratios
Term
What is the formula for the O2 content of the blood?
Definition
=(Hgb x 1.34) x % saturation + (PO2 x 0.0031)
Term
Above what partial pressure is hemoglobin almost totally saturated?
Definition
70 mm Hg
Term
What is the P50 and its value?
Definition

the oxygen partial pressure when hemoglobin is 50% saturated with oxygen

 

28 mmHg 

Term

What partial pressure defines arterial hypoxemia?

 

Respiratory failure? 

Definition

< 70 mmHg

 

<50 mmHg 

Term
Where is mixed venous oxygen measured?
Definition
pulmonary artery
Term
What is the formula for oxygen delivery?
Definition
= oxygen content x cardiac output x 10
Term

What is the normal level for indexed oxygen delivery?

What is the critical level? 

Definition

500-600 ml per minute

 

400 ml per minute 

Term
What is the alveolar-arterial oxygen difference?
Definition
the difference between the calculated alveolar PO2 and the directly measure arterial PO2. a measure of the adequacy of gas exchange in the lungs
Term
What should the physician evaluate in a patient with hypoxemia?
Definition

the alveolar arterial oxygen difference

the response to supplemental oxygen 

Term
If hypoxemic patients have normal alveolar-arterial oxygen difference, what are some physiologic causes?
Definition

high altitude

low oxygen concentration in inspired gas

alveolar hypoventilation 

Term
If hypoxemic patients have increased alveolar-arterial oxygen difference, what are some physiologic causes?
Definition

diffusion abnormalities

ventilation perfusion imbalance

shunting 

Term
What are some causes for alveolar hypoventilation?
Definition

decreased tidal volume

decreased respiratory rate

increase in dead space

increase in CO2 production without a corresponding increase in minute ventilation 

Term
What is an intrapulmonary shunt?
Definition
occurs in an area of the lung that is totally non-ventilated but is well perfused, will have a V/Q ratio of zero
Term
What does an intrapulmonary shunt result from?
Definition

alveoli that are filled with fluid

complete obstruction of an airway

total collapse of alveoli (atelectasis) 

Term
What is the pressure in the pleural space relative to atmospheric pressure?
Definition
negative
Term
What is hysteresis?
Definition
a larger lung colume at any given change in pressure during deflation, due to airway closure and trapping of air during expiration
Term
What molecule is responsible for lowering surface tension within the alveoli?
Definition
dipalmitoylphosphatidylcholine
Term
What is the central inspiratory activity integrator?
Definition
postulated group of cells located within the medullary reticular formation that collects a background amount of pro-inspiratory information, these neurons stimulate the dorsal respiratory group of neurons
Term
What is the dorsal respiratory group?
Definition
associated with inspiration, demonstrate a rhythmic change in membrane potential that is modified by other input. generates efferent information that activates the muscles of inspiration.
Term
What is the ventral respiratory group?
Definition
the rostral and caudal sections are associated with expiration and the intermediate with inspiration. primarily involved with expiration, especially when forced expiration is required
Term
What is the role of the intermediate section of the ventral respiratory group?
Definition
inspiratory, increases the caliber of the airways in the pharynx and larynx during inspiration, also involved in generating the respiratory rhythm
Term
What is the inspiratory cutoff switch?
Definition
influences the dorsal respiratory group in a negative way, thus inhibiting inspiration and allowing expiration. activated by the ventral respiratory group and the pneumotaxic center within the pons
Term
What is the apneustic center?
Definition
impinge upon the dorsal respiratory group and stimulate inspiration.. normally held in check by influences from higher centers
Term
What is apneustic breathing characterized by?
Definition
series of prolonged inspiratory gasps that is ended by a brief and rapid expiratory effort. poor prognostic sign
Term
What is the pneumotaxic center?
Definition
can inhibit inspiration when stimulated. not required for normal rhythmic breathing, but fine tuning; may be able to influence the tidal volume by terminating inspiration and thus influence the respiratory rate
Term
What controls voluntary breathing?
Definition
cortex
Term
What are type I cells in the carotid body?
Definition
glomus cells that are the actual chemoreceptors. respond to a decrease in oxygen by inhibiting K channels which results in membrane depolarization and activation of voltage-gated Ca channels
Term
What are type II cells in the carotid body?
Definition
similar to glial cells and form a supportive environment for the glomus cells
Term

Afferent info from the aortic bodies is carried by what nerve?

 

 

Definition
vagus
Term
Afferent info from the carotid bodies is carried by what nerve?
Definition
glossopharyngeal
Term
What are slowly adapting stretch receptors?
Definition
respond to stretch of the airway muscles, rate of neural firing slowly decays during conditions of constant stimulus
Term
What is the Hering-Breuer reflex?
Definition
initiates at lung volumes above the normal range and results in a decrease in the tidal volume and a decrease in the frequency of breathing, also stimulates expiration, protecting the lungs from over inflation
Term
What receptors are probably responsible for coughing?
Definition
irritant receptors
Term
Where are juxtacapillary receptors and what are they innervated by?
Definition
located both in the alveoli walls near the pulmonary capillaries and airway tissues and are innervated by small unmyelinated C fibers.
Term
What are jextacapillary receptors?
Definition
respond to both chemical and mechanical stimuli much like the irritant receptors and are rapidly adapting. stimulation results in rapid, shallow breathing, bronchoconstriction and the production of mucus
Term
What is plethysmography?
Definition
the patient sits within an air-tight body box that accurately measures a change in pressure with inspiration and expiration.
Term
What is the formula for maximum expiratory flow?
Definition
Vmax= elastic recoil/ upstream resistance
Term
What does the loop of Henle remove?
Definition
solute without an appreciable amount of solvent, liquid leaving the loop is relatively dilute
Term
What is the early distal convoluted tubule associated with?
Definition
Na and Cl reabsorption; also H, K, and ammonia secretion, normally impermeable to water movement
Term
What percent of the entire glomerular filtrate is reabsorbed back into the body?
Definition
99%
Term
What does the glomerulus do?
Definition
forms an ultrafiltrate of plasma free of all formed cells and plasma proteins, produces approximately 187 L of fluid per day
Term
What types of cells make up the cortical collecting tubules and the collecting ducts?
Definition
principal and intercalated cells
Term
What is the function of the principal cell?
Definition
reabsorption of sodium, chloride, potassium and water
Term
What is the function of alpha intercalated cells?
Definition
secrete hydrogen but do not reabsorb sodium, play a significant role in acid-base balance
Term
What is the function of beta intercalated cells?
Definition
secrete bicarbonate under appropriate conditions, play a role in acid-base balance
Term
What is the function of the proximal convoluted tubule?
Definition
reabsorbs 2/3 or more of the filtered load of many compounds: Na, Cl water, bicarbonate, glucose, K, phosphate, Ca); secrets H, organic acids, and ammonia
Term
What is the function of the cortical collecting tubule?
Definition
reabsorbs Na, Cl, water, etc under hormonal control. secrets K, H and ammonia, differential permeability to water and urea in response to hormonal stimulation
Term
What is the function of the collecting duct?
Definition
area where the final concentration of the urine is decided. the collecting ducts can reabsorb solute and depending upon the nature of hormonal influences, can reabsorb variable amounts of water
Term
Which region of the kidney has high osmotic pressure?
Definition
medullary region
Term
What is the function of peritubular capillaries?
Definition
return materials to the body which were reabsorbed by the tubules or they can provide materials to the tubules for secretion
Term
What are vasa rectae?
Definition
specialized peritubular capillary bed which is only associated with juxtamedullary nephrons, characterized by parallel loops and act as a counter-current exchange mechanism which allows the medullary region to remain properly hypertonic which allows the collecting ducts to effectively concentrate the urine
Term
What is GT balance?
Definition
it means that no matter what happens at the glomerulus, it will be compensated for in the tubules; more filtration leads to more reabsorption
Term
What is the filtration pressure equilibrium?
Definition
the point along the apillary length where the protein concentration in plasma increases and the net hydrostatic pressure decreases to just match the filtration and reabsorptive forces
Term
What is the formula for clearance of a substance?
Definition
clearance of X = (the urine concentration of X times the urine flow rate)/ the plasma concentration of X
Term
What is solvent drag?
Definition
the transport of an osmotically active molecle across a water permeable membrane
Term

What decreases phosphate resabsorption?

 

Increases? 

Definition

decreases: increased parathyroid hormone, increased ACTH, decreased rate of Na reabsorption

 

increases: vitamin D3, increased plasma Ca 

Term
How does ADH work?
Definition
moves aquaporin AQP2 into the apical membrane of the renal collecting duct
Term
How does sodium move across the luminal membrane of the PCT?
Definition
enters the proximal tubular cell from the ultrafiltrate down its electrochemical potential gradient primarily in connection with cotransport systems
Term
How does sodium move across the basolateral membranes of the proximal convoluted tubule?
Definition
active transport, must move against both an electrical and a concentration gradient, need a Na/K ATPase
Term
How does chloride move across the luminal membrane of the PCT?
Definition
moves from the tubular fluid into the cell against an electrical gradient but down its concentration gradient
Term
How does Cl- move across the basolateral membranes of the PCT?
Definition
Cl- movement from the cell interior into the peritubular fluid involves a favorable electrical gradient and an adverse concentration gradient
Term
What is the luminal membrane of the PCT?
Definition
separates the interior of the cell from the tubular fluid in the tubular lumen
Term
What is the peritubular membrane?
Definition
separate the interior of the cell from the peritubular space
Term
What happens in the ascending limb of the loop of Henle?
Definition
Na and Cl are passively transported out and water is impermeable
Term
By the time the filtrate reaches the early distal convoluted tubule, is it hyper or hypo tonic with respect to blood plasma?
Definition
hypotonic
Term
How do thiazide diuretics work?
Definition
they specifically inhibit the Na/Cl cotransport system in the early distal convoluted tubule
Term
How does angiotensin II help to balance total body solute?
Definition
acts as a potent vasoconstrictor affecting the GFR and also directly stimulates aldosterone production, can also increase sodium and water reabsorption by the PCT via Na/H exchange and Na/K ATPase system activity. also induces thirst
Term
How does aldosterone control sodium reabsorption?
Definition
acts primarily on the cortical collecting tubules and the collecting ducts to increase sodium permeability across the distal luminal cellular membrane, diffuses into the cell across the basolateral membrane and binds to a high affinity mineralocorticoid receptor
Term
How does ANF work?
Definition
dilates the renal vasculature and increases the GFR, acts on the kidney to inhibit the reabsorption of sodium
Term
How does bradykinin, prostaglandin E, and PGI2 affect the renal tubules?
Definition
inhibits sodium reabsorption
Term
What is an area of automatic K reabsorption?
Definition
PCT
Term
Which nephron segment controls the circulating plasma K concentration?
Definition
distal nephron
Term
How does potassium enter the principal cell?
Definition
Na/K ATPase system, transports K into the cell
Term
How is bicarbonate reabsorbed?
Definition
H secretion paired with Na reabsorption, the secreted H spontaneously combines with HCO3 to form H2CO3, carbonic anhydrase quickly catalyzes the dissociation of H2CO3 into CO2 and water, both of which passively diffuse across the luminal membrane into the cell; there is also an antiport system with Cl-
Term
What is the primary regulator of calcium reabsorption/excretion by the kidney?
Definition
parathyroid hormone
Term
What is the purpose of countercurrent multiplication?
Definition
allows the tubule to participate in the process of producting a concentrated urine
Term
Which structures are part of the system which is responsible for the concentration of urine?
Definition
the loops of Henle, the collecting ducts, and the vasa recta
Term
How does countercurrent multiplication work (4 requirements)?
Definition

1 solute is actively reabsorbed from the ascending limb of the loop

2 the permeability of the ascending limb to solvent is extremely low

3 the solute which is transported out of the ascending limb enters the medullary interstitium and increases the osmolarity within the interstitium (descending limb permeable to solute and solvent, so tubular fluid becomes more concentrated as it flows down the descending limb to equilibrate with the interstitium)

4 the physical length of the loop plays a role in the degree to which the osmotic gradient within the medullary interstitium can rise 

Term
Which nephrons function in countercurrent multiplication?
Definition
juxtamedullary
Term
What determines how many cycles of countercurrent multiplication can occur, and therefore determines the degree of solute concentration at the tip of the loop?
Definition
the length of the loop
Term
What sections of the nephron are significantly involved with the action of ADH?
Definition
the cortical collecting tubules and the collecting duct
Term
What are the cortical collecting tubules?
Definition
a connection between the distal tubule and the collecting duct located in the renal cortex
Term
How is urea measured clinically?
Definition
BUN (blood urea nitrogen)
Term
Which transporter does ADH stimulate?
Definition
UT1
Term
What is the function of the vasa recta?
Definition
responsible for removing those materials from the renal medulla that are deposited there by the loop of Henle or the collecting ducts, also responsible for providing oxygen and nutrients
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