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A. White- Human Physiology > Exam III > Flashcards

Exam III Flashcards

1
Q

What are the three components of the filtration barrier?

A

Endothelium

Basement membrane

Podocytes

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2
Q

What is the glomerular filtration rate determined by?

A

osmotic and hydrostatic forces.

capillary filtration coefficient

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3
Q

What is the daily glomerular filtration rate

A

125 mL/min or 180 L/day

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4
Q

What are some diseases that lower the glomerular filtration coefficient?

A

diabetes, hypertension

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5
Q

What is minimal change nephropathy?

A

A loss of negative charge in the basement membrane

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6
Q

What is hydronephrosis?

A

Distension and dilation of renal pelvices

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7
Q

How is glomerular filtration rate calculated?

A

GFR = K1(Pg-Pb-Lg+Lb)

Pg = glomerular hydrostatic pressure
Pb = Bowman's capsule hydrostatic pressure
Lg = glomerular capilly coilloid osmotic pressure
Lb = colloid osmotic pressure of Bowman's capsule
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8
Q

Increasing what factor will increase glomerular colloid osmotic pressure?

A

filtration fraction

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9
Q

What effect does arterial pressure have on GFR?

A

it increases it.

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10
Q

What effect does afferent pressure have on GFR?

A

It decreases it

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11
Q

What effect does efferent pressure have on GFR?

A

It increases it

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12
Q

What effect does activation of the sympathetic system have on GFR?

A

It constricts arterioles and decreases blood flow and GFR.

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13
Q

What hormones affect GFR?

A

Norepinephrine

Endothelin

Angiotensin II

Endothelial-derived NO

Prostaglandins and bradykinin

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14
Q

What is endothelin released by?

A

damaged vascular endothelial cells of the kidneys and other tisues.

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15
Q

What effect does endothelin have on GFR?

A

it leads to vasoconstriction and reduced GFR.

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16
Q

How does angiotensin affect GFR?

A

It constricts Efferent arterioles, which increases GFR.

Afferent arterioles are protected against the effects of angiotensin II.

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17
Q

What is the origin of nitric oxide?

A

endothelial cells.

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18
Q

What is the effect of nitric oxide on GFR?

A

It helps maintain renal vasodilation

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19
Q

What is the effect of prostaglandins and bradykinins on GFR?

A

It offsets effects of sympatheti and angiotensin II vasoconstrctor effects.

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20
Q

What does autoregulation refer to?

A

maintaining a relatively consant GFR and renal blood flow.

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21
Q

What are the two tubuloglomerular feedback mechanisms for autoregulation?

A

afferent

efferent

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22
Q

What are the comonents of the juxtraglomerular complex (autoregulation)?

A

macula densa cells

juxtaglomerular cells in afferent and efferent arterioles.

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23
Q

When GFR decreases, how is the flow rate affected?

A

The flow rate int he loop of Henle slows down. There is increased reabsorption of sodium and chloride ions here, and less at the macula densa.

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24
Q

Once the macula densa reabsorbs less sodium chloride, what does it signal?

A

increased renin release from the JG cells. This increases angiotensin and efferent arteriolar resistance.

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25
Q

Where is glucose absorbed?

A

proximal convoluted tubule

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26
Q

What receptor reabsorbs 90% of glucose in the early proximal tubule?

A

SGLT2 via secondary active transport

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27
Q

What is the difference between sodium absorption in the first and second half of the proximal tubule?

A

In the first half, reabsorption is via co transort along with glucose, amino acids, and other solutes.

In the second half, reabsorption is mostly with chloride ions.

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28
Q

How is sodium transported in the peoximule tubule?

A

via antiport with H+

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29
Q

What is the thin descending segment of the loop of henel highly permeable to?

A

water.

It is also moderately permeable to most solutes, including urea and sodium.

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30
Q

What is the thin ascending segment of the loop of Henle impermeable to?

A

water

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31
Q

What diuretics are used at the thick ascending segment of the loop of Henle?

A

furosemide

etacrynic acid

bumetanide

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32
Q

What is the distal tubule impreameble to?

A

water and urea

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33
Q

Where are principal and intercalated cells found?

A

In the late distal tubule and collecting tubules

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34
Q

What do principal cells reabsorb and secrete?

A

reabsorb Na+, secrete K+

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35
Q

What diuretics are used at the principal cells?

A

spironolactone, eplerenone, amilrodie, triameterene

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36
Q

What do intercalated cells reabsorb and secrete?

A

reabsorb potassium, secrete hydrogen ions.

It also reabsorbs water in the presence of ADH

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37
Q

What is the permeability to water in the medullary collecting duct controlled by?

A

ADH

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38
Q

what does the collecting duct reabsorb and secrete?

A

reabsorb: Na, Cl, H2O (in the presence of ADH), urea, HCO3
secrete: H+

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39
Q

What is the source of aldosterone?

A

adrenal cortex

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40
Q

What is the functon of aldosterone?

A

increase sodium reabsorption and stimulate potassium secretion.

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41
Q

Where is the site of actionof aldosterone?

A

the principal cells of cortical collecting ducts

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42
Q

An increase of what ionin the extracellular fluid causes the secretion of aldosterone?

A

potassium

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43
Q

What happens in Addison’s disease?

A

A marked loss of sodium and accumulation of potassium due to the absence aldosterone.

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44
Q

What syndrome involves the hypersecretion of aldosterone?

A

Conn’s syndrome

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45
Q

What does angiotensin II directly stimulate?

A

sodium reabsorption in proximal tubules, loops of Henle, distal tubules and collecting tubules.

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46
Q

What is he source of ADH?

A

posterior pituitary

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47
Q

What is the function of ADH?

A

to increase water reabsorption

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48
Q

Where does ADH bind?

A

to V2 receptors in late distal tubules, collecting tubules and collecting ducts.

It increases the formation of cAMP

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49
Q

What is the source of ANP?

A

cardiac atrial cells in response to distension

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50
Q

what is the function of ANP?

A

to inhibit reabsorption of sodium and water.

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51
Q

What is the source of PTH?

A

parathyroid glands

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52
Q

What is the function of PTH?

A

increases calcium reabsorption

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53
Q

How much water can be excreted by the kidneyes per day when there is a large excess of water in the body?

A

20 L/day

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54
Q

What is the maximal urine concentration that the kidneys can produce?

A

1200 - 1400 mOsm/L

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55
Q

What are the requirements for forming concentrated urine?

A

presence of ADH

High osmolarity of the renal medullary interstitial tubule.

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56
Q

What is the obligatory urine volume, and why is it necessary?

A

0.5 L/day; it is excreted in order to get rid of waste products of metaolism and ions that are ingested.

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57
Q

Where in the kindey tubule are most of the filtered electrolyetes reabsorbed?

A

in the proximal tubule.

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58
Q

What is the descending loop of Henle permeable to?

A

water

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59
Q

When does the tubular fluid become more dilute?

A

as it moves up the thin ascending loop of Henle. Sodium chloride is reabsorbed here.

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60
Q

What is the role of the osmoreceptor ADH feedback mechanism?

A

It controls extracellular fluid sodium concentration and osmolarity.

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61
Q

When the extracellular fluid osmolarity is high, what effect does this have on osmorecetor ells in the anterior hypothalamus?

A

The cells shrink. ADH is then released, which increases water permeability in distal nephron segments.

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62
Q

When does extracellular osmolarity increase?

A

When therei s a deficit in water. This causese ADH secretion and subsequent water reabsorption.

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63
Q

What is the extracellular fluid potassium concentration?

A

4.2 mEq/L

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64
Q

What is the relationship between insulin and potassium?

A

Insulin stimulates potassium uptake by cells.

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65
Q

What is the relationship of aldosterone and potassium?

A

Aldosterone increases potassium uptake by cells.

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66
Q

what is the disorder that involves an excess secretion of aldosterone?

A

Conn’s syndrome

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67
Q

What is the disorder that invovles a deficiency in aldosterone secretion?

A

Addison’s disease

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68
Q

What is the relationship between beta-adrenergic stimulation and potassium?

A

epinephrine stimulates potassium uptake by cells.

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69
Q

What is the relationship between metabolic acidosis and extracellular potassium?

A

extracellular potassium increases in metabolic acidosis due to reuctionin activity of the Na/K ATPase pump.

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70
Q

What are the effects of hyperkalemia?

A

cell lysis

strenous exercise

increased extracellular fluid osmolarity

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71
Q

What is a buffer?

A

A substance that can reversibly bind H+.

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72
Q

What are three important buffer systems?

A

bicarbonate

phosphate

proteins as buffers

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73
Q

What is the most important extracellular buffer system?

A

bicarbonate buffer system

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74
Q

What is metabolic acidosis?

A

a decreased concentration of bicarbonate

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75
Q

What is metabolic alkalosis?

A

an increased concentration of bicarbonate

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76
Q

What is respiratory acidosis?

A

an increased concentration of carbon dioxide

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77
Q

What is respiratory alkalosis?

A

a decreased concentration of carbon dioxide.

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78
Q

What role does the phosphate buffer system play?

A

It biffers renal tubular fluid and intracellular fluids

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79
Q

What is the primary method for removing nonvoltaile acids?

A

by excretion.

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80
Q

In order to reabsorb bicarbonate, what must happen to it?

A

It must react with secreted hydrogen ion to form carbonic acid before it can be reabsorbed.

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81
Q

What are the three ways that extracellular H+ is regulated?

A

Reabsorption of filtered bicarbonate ions

Secretion of hydrogen ions

Production of new bicarbonate ions.

82
Q

Where in the kidney tubules does hydrogen ion secretion and reabsorption occur?

A

Hydrogen ion secretion occurs via secondary active transport in all parts of the tuules except the descending and ascending limbs of the loops of Henle.

83
Q

Where does primary acive hydrogen secretion begin?

A

In thelate distal tubules (intercalated cells)

84
Q

Where does the majority of bicarbonate reabsorption occur?

A

proximal tubule

85
Q

How are acidosis and alkalosis corrected?

A

via incomplete titration. Each time a hydrogen ion is formed in the tubular epithelial cells, a bicarbonate ion is formed and released back into the blood.

86
Q

How does the tubular epithelium secrete hydrogen?

A

via primary active transport

87
Q

How does the proximal tubule secrete hydrogen?

A

via secondary counter-transport.

88
Q

What is the lower limit of pH that can be achieved in normal kidneys?

A

4.5

89
Q

The loss of bicarbonate ions is the ___ as adding hydogen ions to the extracellular fluid.

A

same

90
Q

Why can only a small partof the excess hydrogion secrete be excreted in the ionic form in urine?

A

Because the minimal urine pH is about 4.5.

91
Q

How are excess hydrogen ions eliminated?

A

Through binding with phosphate or ammonia ions.

92
Q

How can the kidneys correct alkalosis?

A

by failing to reabsorb all the filtered bicaronate ion

93
Q

When does acidosis occur?

A

when the ratioof bicarbonate ion to carbon dioxide in extracellular fluid decreases.

94
Q

What is the primary compensatory resonse of respiratory acidosis?

A

Increase in plsam bicarbonate ion

95
Q

What is the primary compensatory response for metabolic acidosis?

A

increase ventilation rate

96
Q

When does alkalosis occur?

A

When there is an increase in the ratio of bicarbonate to hydrogen ion concentration.

97
Q

What is the primary compensatory response of alkalosis?

A

reduction in plasma bicarbonate ion concentration caused by renal excretion of bicarbonate ion.

98
Q

what is the primary compensatory response of metabolic alkalosis?

A

decreased ventilation\

Increased renal bicarbonate ion excretion.

99
Q

What is total lung capacity?

A

the maximum volume of gas the lungs can hold.

100
Q

What is tidal volume?

A

the volume of air that is inspired or expired with each breath at rest. 500 ml

101
Q

What is insiratory reserve volume?

A

Volume f air that can be inspired in addition to tidal volume with forceful inspiration. 3000 mL

102
Q

What is expiratory reserve volume?

A

Additional volumeof air that can be expired at end of tidal volume by forceful expiration. 1100 mL

103
Q

What is residual volume?

A

volume of air remaining in lungs after force expiration. 1200 mL.

104
Q

What vital capacity?

A

The sum of all the volumes that can be insired or exhaled. 4600 mL

105
Q

What is total lung capacity?

A

The sum of all the volumes = vital capacity plus residual volume. 5800 mL.

106
Q

What is inspiratory capacity?

A

The sum of all volumes above resting capcity = tidal volume plus inspiratory reserve volume. 3500 mL

107
Q

What is functional residual capcity?

A

2300 mL. The sum of volumes below resting capacity = expiratory reserve volume + residual volume.

108
Q

What is minute ventilation?

A

Total volume of gases moved into or out of the lungs per minute; calculated as breaths per minute x tidal volume.

109
Q

What is alveolar ventilation?

A

Total volume of gases that enter spaces participating in gas exchange per minute. Calculated as breaths per minute x (tidal volume - dead space).

110
Q

What is anatomic dead space?

A

trachea, bronchi and bronchioles

111
Q

What is physiological dead space

A

anatonmic dead space + ventilated alveoli with poor or absent perfusion.

112
Q

What is the total dead psace in a normal individual?

A

0.15 L.

113
Q

How is alveolar ventilation calculated?

A

0.35 x breathing rate.

114
Q

What is pleural presure?

A

pressure of the fluid between parietal pleura and the visceral pleura.

115
Q

What is alveolar pressure?

A

Pressure of the air inside the alveoli

116
Q

What is transpulmonary pressure?

A

Difference between the alveolar pressure and the pleural pressure.

117
Q

What is compliance?

A

The extent to which lungs will expand for each unit increase in the transpulmonary pressure. it is a measure of the expansibility of the lungs and trachea.

118
Q

How is compliance calculated?

A

increase in volume/increase in pressure

119
Q

What is surfactant produced by?

A

type II alveolar ells.

120
Q

Why does a saline-filled lung expand more easily than an air-filled lung?

A

beacuse there is an absence of surface tension forces. Therei s no air-fluid interface.

121
Q

What happens if air passages laeading from the alveoli are blocked?

A

the surface tension in he alveoli collapses the alveoli.

122
Q

What would happen if there were no surfactant?

A

Pressure would be about 4.5 times as great in the lungs.

123
Q

What is the high pressure, low flow irculation?

A

thoracic aorta to bronchial arteries

124
Q

What is the low pressure, high flow circulation?

A

pulonary artery and branches to alveoli.

There is high compliance.

125
Q

What is pulmonary arterial pressure?

A

24/9 mm H

126
Q

What is mean pulmonary arterial pressure?

A

15 mm Hg

127
Q

What is let atrium pressure?

A

8 mm Hg

128
Q

What is the pressure gradient in the pulmonary system?

A

7 mm Hg

129
Q

How does failure of the left side of the heart affect pressure?

A

pressure builds up in pulmonary circulation. Blood volume and pressure are increased.

130
Q

What is a physiologic shunt?

A

it contains blood that has bypassed the pulmonary capillaries.

131
Q

What occurs when oxygen concentration in the alveoli is 70% or more below normal?

A

adjacent vessels constrict. Those alveoli that are poorly ventilated get even less blood while those with adequate ventilation get more blood.

132
Q

What is the flow in zone 1?

A

no blood flow

133
Q

What is the flow in zone 2

A

intermittent blood flow only during systole

134
Q

What is the flow in zone 3?

A

continuous blood flow

135
Q

What flow is found in the apices?

A

zone 2 flow. Exercise can convert apices from zone 2 to zone 3 flow.

136
Q

What is the result of obstructing blood supply to one normal lung?

A

blood flow through the other lung is doubled. The pulmonary pressure in the other lungs is only slightly increased.

137
Q

What are agents that constrict pulmonary arterioles?

A

norepinephrine

epinephrine

angiotensin II

some prostaglandins

138
Q

What are some agenst that dilate pulmonary arterioles?

A

isoproterenol

acetylcholine

139
Q

What is the result of sympathetic vasoconstriction in the pulmonary system/

A

pulmonary blood flow is decreased by 30%, and blood is mobilized from pulmonary reserves.

140
Q

Pulmonary arterial pressure rises little during maximum exercise. Why is this so?

A

becaue capillaries open and flow rate increases.

141
Q

In left heart failure, what occurs at the left atrium?

A

blood begins to dam up.

142
Q

What is the mean filtration pressure in the lungs?

A

1 mm Hg

143
Q

What is the most common cause of pulmonary edema?

A

left sided heart failure or mitral valve disease.

Damage of pulmonary blood capillary membranes can also occur.

144
Q

What happens if the pressure in the lungs becomes positive (greater than -4 mm Hg)?

A

the lungs tend to collapse.

145
Q

What are causes of pleural effusion?

A

blockage of lymphatic drainage from pleural cavity

Cardiac failure

Reduced plasma colloid osmotic presure

Infection/inflammation

146
Q

How does hypoxia affect presure in the pulmonary artery?

A

pressure is increased due to prostaglandins.

147
Q

What are the results of a bronchial obstruction?

A

Decline in pH and vasoconstriction of pulmonary vessels.

148
Q

What is the most abundant gas in air?

A

nitrogen

149
Q

What is daltons law?

A

Ptotal = sum of partial pressures

150
Q

What is Boyle’s law?

A

P = 1/V

151
Q

What is Henry’s law?

A

the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.

152
Q

What is pressure directly proportional to?

A

the concentration of the gas molecules.

153
Q

How is partial pressure calciulated?

A

partial pressure = [dissolved gas]/sol. coefficient

154
Q

What is the relationship between vapor pressure and temperature?

A

as vapor pressure increases, temperature increases.

155
Q

What factors affect the rate of gas diffusion in a fluid?

A

solubility of gas in the fluid

Cross sectional area of the fluid

Distance through which the gas must diffuse

Molecular weight of the gase

Temperature of the fluid

156
Q

What is oxygen concentration in the alveoli controlled by?

A

rate of absorption of oxygen into the blood

rate of new oxygen entry into the lungs

157
Q

Carbon dioxide concentration is controlled by what factors?

A

rate of carbon dioxide excretion

alveolar ventilation

158
Q

What factors determine how rapidly a gas will pass through the respiratory membrane?

A

membrane thickness

surface area

diffusion coefficient of gas

partial pressure difference of gas between two sides of the membrane.

159
Q

What does the Va/Q ratio refer to?

A

alveolar ventilation/blood flow

160
Q

When Va/Q = 0, what type of obstruction i spresent?

A

an airway o bstruction. There is no ventilation, but there is perfusion. The blood gas composition remains unchanged.

161
Q

When Va/Q = infinity, what type of obstruction is present?

A

a vessel obstruction. There is ventilation, but no gas exchange.

A physiologic shunt is made.

162
Q

What is physiologic dead space?

A

shunted blood + anatomic dead space

163
Q

When diffusing capacity increases during exercise, what happens in the lungs?

A

There is a more ideal V/Q ratio

There is increased surface area of capillaries participating in diffusion.

164
Q

What factors determine tissue PO2?

A

Rate of oxygen transport to the tissues

Rate of oxygen consumption by the tissues

165
Q

When PO2 is ___, oxygen binds with hemoglobin

A

high

166
Q

When PO2 is ___, oxygen is released from hemoglobin.

A

low

167
Q

What factors cause the oxygen-hemoglobin curve to shift to the right?

A

increased hydrogen ions

increased CO2
Increased temperature

increased BPG

168
Q

What direction is the oxygen-hemoglobin curve shifted when there is an increase in carbon dioxide and H+ ions?

A

to the right

169
Q

What direction is the oxygen-hemoglobin curve shifted when there is a decrease in blood carbon dixode and H+ ions?

A

to the left

170
Q

How is carbon dioxide transported?

A

A small amount is dissolved in the blood

70% is transported as carbonic acid

Remainder is transported as carbamino hemoglobin

171
Q

What is the bohr effect?

A

An increase in blood carbon dioxide causese oxygen to be displaced from hemoglobin. This shifts the oxygen-hemoglobin curve to the right.

172
Q

What is the Haldane effect?

A

Binding of oxygen with hemoglobin displaces carbon dioxide from blood. The binding of oxygen cauese hemoglobin to become a stronger acid, and more acidic hemoglobin ha less of a tendency to bind with carbon dioxide.

173
Q

What two respiratiory groups are located in the medullary respiratory centers?

A

dorsal respiratory group

ventral respiratory group

174
Q

What respiratory groups are located in the pontine respiratory centers?

A

apneustic center

pneumotaxic center

175
Q

What is the functionof the dorsal respiratory group?

A

It sets the basic rhythm of respiration.

176
Q

What respiratory group establishes the ramp signal?

A

dorsal respiratory group

177
Q

How is respiration controlled?

A

by limiting the point at which ramp suddenly ceasese. The earlier ramp ceases, the shorter the duration of inspiration and respiration.

178
Q

What does a strong PRG signal result in?

A

30 - 40 breaths/minute

A weak PRG signal results in 3-5 breaths/minute.

179
Q

What does the pneumotaxic center conrol?

A

the rate and depth of breathing.

180
Q

The loss of function of what respiratory center causese prolonged inspiratory gasping?

A

apneustic center

181
Q

What respiratory group is inactive during normal quiet respiration?

A

ventral respiratory group

182
Q

What complex generates the timing and length of the respiratory rhythm?

A

the pre-botzinger complex

183
Q

What is the Hering-breuer inflation reflex?

A

Stretch receptors in muscular portions of walls of bronchi and bronchioles activate dorsal respiratory group neurons. This inhibits the inspiratory ramp signal.

184
Q

What is the relationship between chemoreceptors and hypoxia/hypercapnia?

A

chemoreceptors increase their rate of activity when hypoxia or hypercapnia occur.

185
Q

Where are central chemoreceptors located?

A

on the ventral surfae of the medulla. They are indirectly sensitive to carbon dioxide levels int he blood.

186
Q

Where are peripheral receptors located?

A

in the aortic arch. They are sensitive to concentrations of oxygen, carbon dioxide and hydrogen ions.

187
Q

What are central receptors sensitive to?

A

H+.

188
Q

Sensitivty to increased levels of carbon dioxide lasts for several hurs, but then begins to decline. This is due to adjustments by what organ?

A

The kidneys.

They increase bicarbonate levels in the blood.

189
Q

Where are most peripheral receptors located?

A

in the carotid bodies at the bifurcation of the common carotids.

190
Q

What are the two types of carotid body cells?

A

type I (glomus) and type II (sustenacular cells)

191
Q

What effect does decreased PO2 have on channels?

A

It closes channels and results in a depolarization that opens calcium channels, leading to neurotransmitter release.

192
Q

Where are slow-adapting stretch receptors located?

A

within the airways of the lungs.

193
Q

What do signals from the slow adapting stretch receptors do?

A

terminate inspiration

prolong expiration

194
Q

What are signals for the slow adapting stretch receptors important for?

A

controlling respiration in infants and adults during exercise.

195
Q

What is the function of rapidly-adapting pulmonary stretch receptors?

A

eliciting a cough.

196
Q

Where are J receptors located?

A

in the alveolar wall.

197
Q

What are J receptors sensitive to?

A

pulmonary edema

198
Q

What does the stimulation of J receptors elicit?

A

a cough and tachypnea

199
Q

What is Cheyne stokesbreathing

A

hyperpnea

gradual decrease

apnea

repeat of pattern

200
Q

What factors can cuase Cheyne-Stokes breathing?

A

A long delay in the transport of bood from the lungs to the brain.

Increased negative feedback.

A. White- Human Physiology (32 decks)

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