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the respiratory system Flashcards

1
Q

respiration has multiple meanings:

A

cellular respiration (intracellular reaction producing ATP) and external respiration (movement of gases between the environment and body cells)

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2
Q

external respiration involves four processes

A
  1. exchange of air between the atmosphere and lungs (ventilation), including inspiration (inhalation) and expiration (exhalation).
  2. exchange of O2 and CO2 between lungs and blood
  3. Transport of O2 and CO2
  4. Exchange of gases between blood and cells
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3
Q

external respiration requires coordination between

A

the respiratory and cardiovascular systems

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4
Q

the respiratory system includes

A
  1. conducting system of airways leading to the lungs
  2. alveoli and pulmonary capillaries for gas exchange
  3. bones and muscles of the thorax and abdomen aiding in ventilation
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5
Q

the respiratory system is divided into

A

upper respiratory tract: mouth, nasal cavity, pharynx and larynx
lower respiratory tract: trachea, primary bronchi, their branches and lungs (thoracic portion)

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6
Q

the thorax is enclosed by the

A

spine, rib cage, and associated muscles, collectively known as the thoracic cage

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7
Q

the chest wall is composed of

A

the ribs, and spine, forms the sides and top of the thoracic cage, while the diaphragm forms the floor.

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8
Q

the diaphragm is

A

a dome shaped sheet of skeletal muscle

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9
Q

two sets of intercostal muscles, internal and external

A

connect the 12 pairs of ribs

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10
Q

additional muscles, the sternocleidomastoids and the scalenes extend from

A

the head and neck to the sternum and the first two ribs

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11
Q

the thorax functions as a sealed container with three membranous sacs

A

the pericardial sac (containing the heart) and two pleural sacs (each surrounding a lung)

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12
Q

the esophagus, thoracic blood vessels and nerves pass

A

between the pleural sacs.

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13
Q

the lungs are light, spongy organs primarily filled with

A

air spaces and nearly fill the thoracic cavity, resting on the diaphragm

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14
Q

the bronchi are semi-rigid airways that connect the lungs to the

A

trachea

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15
Q

each lung is encased in a

A

double walled pleural sac, with membranes lining the thorax and covering the lung surface

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16
Q

the pleural membranes contain elastic connective tissue and numerous capillaries, held together by a

A

thin film of pleural fluid

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17
Q

pleural fluid

A

creates a moist, slippery surface for membrane movement and holds the lungs against the thoracic wall

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18
Q

the fluid bond between pleural membranes keeps the lungs partially

A

inflated and adhered to the thoracic cage, even at rest

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19
Q

air enter the upper respiratory tract through the mouth and nose, passing into the

A

pharynx, which serves as a common passageways for foods, liquids, and air

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20
Q

from the pharynx, air flows through the larynx into the trachea

A

the larynx contains vocal cords that create sound by vibrating as air moves past them.

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21
Q

the trachea is a

A

semi-flexible tube supported by 15 to 20 C shaped cartilage rings and extends into the thorax, where it branches into a pair of primary bronchi, one for each lung

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22
Q

within the lungs, the bronchi branch repeatedly into

A

smaller bronchi, which are also semirigid tubes supported by cartilage

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23
Q

the smallest bronchi branch into bronchioles which are

A

small collapsible passageways with walls of smooth muscle. these continue to branch until they from respiratory bronchioles, transitioning ot the exchange epithelium of the lung

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24
Q

the diameter of the airways decrease from the trachea to the bronchioles, but the number of airways increase geometrically, resulting in an

A

increased total cross sectional area with each division

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25
Q

the total cross sectional area is the lowest in the upper respiratory tract and greatest in the

A

bronchioles, similar to the increase in cross sectional area from the aorta to the capillaries in the circulatory system

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26
Q

the velocity of air flow is inversely proportional to the total cross-sectional area of the airways,

A

meaning it is the greatest in the upper airways and slowest in the terminal bronchioles

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27
Q

the upper airways and bronchi condition air it reaches the alveoli by

A

warming it to body temperature (37°C), adding water vapor to achieve 100% humidity, and filtering out of foreign material

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28
Q

breathing through the nose is more effective at warming and moistening air than

A

breathing through the moth, which can cause chest discomfort in cold weather

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29
Q

air filtration occurs in the trachea and bronchi, which are lined with

A

ciliated epithelium. The cilia are bathed in watery saline layer produced by epithelial cells

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30
Q

the saline layer is created when Cl- is secreted into the lumen by

A

apical anion channels, drawing Na+ into the lumen through the paracellular pathway, creating an osmotic gradient that pulls water into the airways

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31
Q

the CFTR channel, an anion channel on the apical surface of the epithelium is crucial for this process

A

malfunction of this CFTR channel causes cystic fibrosis

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32
Q

the mucociliary escalator is a mechanism where a sticky mucus layer traps

A

inhaled particles larger than 2 macrometers, and cilia move the mucus toward the pharynx

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33
Q

mucus contains immunoglobulins that disable

A

pathogens and can be expectorated or swallowed with stomach acid and enzymes destroying remaining microorganisms

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34
Q

a watery saline layer beneath the mucus is essential for the

A

mucociliary escalator’s function

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35
Q

in cystic fibrosis, inadequate ion secretion reduces fluid movement, trapping

A

cilia in thick mucus, preventing clearance and leading to recurrent lung infections

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36
Q

alveoli

A

are air filled sacs at the ends of terminal bronchioles, primarily responsible for gas exchange with the blood

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37
Q

alveoli are composed of a

A

single layer of epithelium, with two types of epithelial cells: type I and type II

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38
Q

type 1 alveolar cells cover about

A

95% of the alveolar surface area and are very thin to facilitate rapid gas diffusion

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39
Q

type II alveolar cells are

A

smaller, thicker, and produce surfactant, which helps the lungs expand during breathing and minimizes fluid in the alveoli by transporting solutes and water out

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40
Q

alveoli walls lack muscle fibers to avoid obstructing

A

gas exchange, but connective tissue with elastin and collagen fibers provides elastic recoil

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41
Q

the extensive network of capillaries around the alveoli highlights

A

the close relationship between the respiratory and cardiovascular systems, with blood vessels occupying 80%-90% of the space between alveoli for efficient gas exchange

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42
Q

the pulmonary circulation starts with the

A

pulmonary trunk, which carries low oxygen blood from the right ventricle and splits into two pulmonary arteries, each going to a lung

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43
Q

oxygenated blood returns from the lungs to the

A

left atrium via the pulmonary veins

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44
Q

pulmonary circulation hold about 0.5 liters of blood,

A

or 10% of the total blood volume, with 75mL in the capillaries where gas exchange occurs

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45
Q

the lungs receive the entire cardiac output of the right ventricle, which is 5L/min, resulting

A

in a higher blood flow rate through the lungs compared to other tissues

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46
Q

despite the high flow rate, pulmonary blood pressure is low

A

averaging 25/8 mmHg compared to systemic pressure of 120/80 mmHg

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47
Q

the right ventricle pumps with less force due to the

A

low resistance in pulmonary circulation, which is attributed to the shorter length of pulmonary vessels, their distensibility and large cross sectional area of pulmonary arterioles

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48
Q

net hydrostatic pressure in pulmonary capillaries is

A

low, minimizing fluid filtration into the interstitial space

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49
Q

the lymphatic system effectively removes

A

filtered fluid, keeping lung interstitial fluid volume minimal

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50
Q

the short distance between the alveolar air space and the capillary endothelium allows

A

for rapid gas diffusion

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51
Q

respiratory air flow and blood flow are similar because both involve

A

the movement of fluid, but differ as blood is non-compressible liquid and air is a compressible gas

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52
Q

gas laws govern the behavior of gases in air, which is crucial fro the exchange of

A

air between the atmosphere and the alveoli

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53
Q

blood pressure and environmental air pressure are reported in millimeters of mercury

A

respiratory physiologists may also use centimeters of water or kiloPascals for gas pressures

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54
Q

conversion factors:

A

1 mmHg = 1.36cm H2O
760 mmHg = 101.325 kPa

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55
Q

at sea level, normal atmospheric pressure is 760mmHg but it is often

A

designated as 0 mmHg to simplify comparisons of pressure differences during ventilation, regardless of attitude

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56
Q

the atmosphere is a mixture of

A

gases and water vapor

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56
Q

dalton’s law states that

A

the total pressure of a gas mixture is the sum of the pressures of the individual gases

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57
Q

in dry air, at 760 mmHg, 78% of the pressure is due to

A

N2 and 21% is due to O2

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58
Q

the partial pressure of a gas (Pgas) is

A

the pressure exerted by that gas in a mixture

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59
Q

partial pressure is determined by

A

the gas’s relative abundance and is independent of molecular size of mass

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60
Q

water vapor in the air affect the partial pressures of other gases by

A

diluting their contribution to the total pressure

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61
Q

air flow occurs due to

A

pressure gradients, moving from areas of higher pressure to areas of lower pressure

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62
Q

in ventilation, air moves between the external environment and the lungs down pressure gradients created by

A

thoracic movements during breathing

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63
Q

diffusion of gases occurs down concentration (partial pressure) gradients, with oxygen moving from areas of

A

higher partial pressure (PO2) to areas of lower partial pressure

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64
Q

this diffusion is crucial for the exchange of oxygen and carbon dioxide between

A

alveoli and blood and from blood to cells

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65
Q

gas pressure in a sealed container is due to

A

collisions of gas molecules with the container walls and each other

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66
Q

reducing the container size increases

A

collision frequency and pressure

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67
Q

boyle’s law describes the inverse relationship between

A

pressure and volume: P1V1=P2V2

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68
Q

in the respiratory system, changes in chest cavity volume during ventilation create

A

pressure gradients that drive airflow

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69
Q

increased chest volume lowers alveolar pressure causing

A

air to flow into the lungs

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70
Q

decreased chest volume raises alveolar pressure causing

A

air to flow out of the lungs

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71
Q

air movement in the respiratory system is

A

bulk flow, involving the entire gas mixture

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72
Q

a single respiratory cycle includes

A

one inspiration (inhalation) followed by one expiration (exhalation)

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73
Q

pulmonary function is assessed by measuring

A

the volume of air moved during quiet and maximum effort breathing

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74
Q

a spirometer us used to measure

A

the volume of air moved with each breath

75
Q

the air moved during breathing is divided into four lung volumes:

A

tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume

76
Q

tidal volume (Vt)

A

is the volume of air that moves during a single inspiration or expiration averaging about 500mL during quiet breathing

77
Q

inspiratory reserve volume (IRV)

A

is the additional volume you can inspire above the tidal volume

78
Q

expiratory reserve volume (ERV)

A

is the amount of air forcefully exhaled after a normal expiration

79
Q

residual volume (RV)

A

is the volume of air remaining in the lungs after maximal exhalation

80
Q

capacity

A

the sum of two or more lung volumes

81
Q

vital capacity (VC)

A

is the sum of the inspiratory reserve volume, expiratory reserve volume and tidal volume. it represents the maximum amount of air that can be voluntarily moved into or out of the respiratory system with one breath

82
Q

total lung capacity (VC) is

A

the sum of the inspiratory reserve volume and residual volume

83
Q

inspiratory capacity is the

A

sum of tidal volume and inspiratory reserve volume

84
Q

function residual capacity

A

is the sum of expiratory reserve volume and residual volume

85
Q

the thoracic cage muscles and diaphragm act as the

A

pump for respiratory system, expanding the lungs when they contract

86
Q

the lungs are held to the chest wall by

A

pleural fluid

87
Q

primary muscles for quit breathing include the

A

diaphragm, external intercostals, and scalenes

88
Q

forced breathing involves addition chest and

A

abdominal muscles, used during activities like exercise, playing wind instruments, and blowing up balloons

89
Q

air flow for the respiratory tract follows the equation

A

flow is directly proportional to pressure/resistance, meaning air flows due to a pressure gradient (delta P) and decreases with increased resistance (R).

90
Q

for air to move into the alveoli, lung pressure must be

A

lower than atmospheric pressure as per Boyle’s law, which states that an increase in volume leads to a decrease in pressure

91
Q

during inspiration, thoracic volume increases due to the

A

contraction of the diaphragm and rib cage muscles. the diaphragm moves downward about 1.5 cm contributing 60-75% of inspiratory volume change

92
Q

the external intercostal and scalene muscles contract, pulling the

A

ribs upward and outward, contributing the remaining 25-40% of the volume change. this movement is compared to a pump handle and a bucket handle lifting

93
Q

as thoracic volume increases, pressure decreases,

A

allowing air to flow into the lungs

94
Q

the inspiratory muscles include

A

the diaphragm, external intercostals, and scalenes, with their contribution varying based on the type of breathing

95
Q

during the brief pause between breaths, alveolar pressure equal

A

atmospheric pressure (0mmHg at A1)

96
Q

when alveolar and atmospheric pressures are equal,

A

no air flow occurs

97
Q

inspiratory muscles contract, increasing thoracic volume and decreasing

A

alveolar pressure by about 1 mmHg below atmospheric pressure

98
Q

air flows into the alveoli due to the

A

pressure difference

99
Q

alveolar pressure reaches its lowest value halfway through

A

inspiration as thoracic volume changes faster than air can flow

100
Q

as air continues to flow in,

A

alveolar pressure increases until the thoracic cage stops expanding

101
Q

air movement continues briefly under alveolar pressure

A

equalizes with atmosphere pressurea

102
Q

at the end of inspiration, lung volume is at its maximum,

A

and alveolar pressure is equal to atmospheric pressure

103
Q

breathing involves the bulk flow of air into and out of the lungs, with gases like

A

oxygen and CO2 diffusing from the alveoli into the blood

104
Q

diffusion is the movement of molecules from

A

higher to lower concentration. respiratory physiologists use partial pressures to express plasma gas concentrations

104
Q

gases move from regions of higher partial to

A

lower partial pressure.normal alveolar PO2 at sea level is about 100mmHg, while deoxygenated venous blood arriving at the lungs has a PO2 of about 40 mmHg

105
Q

oxygen diffuses from the alveoli into the

A

capillaries reaching equilibrium with arterial blood leaving the lungs at Po2 of 100 mmHg

106
Q

in tissue capillaries, the gradient reverses, cells use oxygen for oxidative phosphorylation, with intracellular PO2 averaging 40mmHg. oxygen diffuses from plasma into

A

cells, and venous blood has the same PO2 as the cells

107
Q

PcO2 is higher in tissues than in

A

systemic capillary blood due to Co2 production during metabolism. Cellular PcO2 is about 46 mmHg compared to arterial plasma PCO2 of 40 mmHg

108
Q

CO2 diffuses out of cells into capillaries, reaching equilibrium with systemic venous blood averaging a PCO2 of

A

46 mmHg

109
Q

at the pulmonary capillaries, venous blood with PCO2 at 46mmHg releases CO2 into the

A

alveoli, which have a PCO2 of 40 mmHg. Blood leaves the alveoli with a PCO2 of 40 mmHg

110
Q

The electron transport system is directly associated with

A

O2 consumption, while the citric acid cycle is directly associated with CO2 production

111
Q

the efficiency of alveolar gas exchange is influenced by several variables, which determine whether

A

arterial blood gases are normal

112
Q

adequate oxygen must reach the alveoli,

A

a decrease in PO2 means less oxygen is available to enter the blood

113
Q

problems can occur with the transfer of gases between the alveoli and

A

pulmonary capillaries

114
Q

low alveolar PO2 can be caused by

A

low oxygen content in the inspired air or inadequate alveolar ventilation

115
Q

altitude significantly affects atmospheric oxygen content due to

A

changes in partial pressure

116
Q

as altitude increase, the partial pressure of oxygen (PO2)

A

in the air decrease

117
Q

water vapor pressure at 100% humidity remains

A

constant regardless of altitude, making its impact on total lung pressure more significant at higher altitudes

118
Q

if the composition of inspired air is normal but but alveolar PO2 is low,

A

the issue is with alveolar ventilation

119
Q

low alveolar ventilation or hypoventilation is characterized by

A

reduced volumes of fresh air entering alveoli

120
Q

pathological changes leading to hypoventilation include:

A
  • decreased lung compliance
  • increased airway resistance
  • CNS depression which slow ventilation rate and decreases depth
121
Q

alveolar PO2 may be normal but arterial PO2 can be low due to

A

impaired oxygen transfer

122
Q

oxygen transfer requires

A

diffusion across the barrier formed by type I alveolar cells and capillary endothelium

123
Q

the diffusion rate is directly proportional to

A

surface area, concentration gradient, and barrier permeability

124
Q

diffusion rate is directly proportional to 1/ distance ^2

A
125
Q

in healthy individuals, the concentration gradient between alveoli and blood is the main factor affecting

A

gas exchange

126
Q

pulse oximeter is a device that measures blood oxygen, how does it work

A

by measuring the light absorbance of hemoglobin at two different wavelengths

127
Q

pulmonary diffusion distance is

A

normally small due to thin alveolar and endothelial cells and minimal interstitial fluid

128
Q

pulmonary edema involves

A

interstitial fluid accumulation, increasing diffusion distance and impairing gas exchange

129
Q

increased pulmonary blood pressure disrupts

A

capillary filtration/reabsorption balance

130
Q

elevated capillary hydrostatic pressure leads to

A

more fluid filtering out, potentially overwhelming lymphatic removal and causing pulmonary edema

131
Q

gas exchange in the alveoli is influence by

A

the solubility of gas which is directly proportional to the pressure gradient of gas, the solubility of the gas in the liquid and temperature

132
Q

higher gas pressure in causes gas to

A

leave the water (while higher gas pressure in air causes gas to dissolve into the water)

133
Q

oxygen has low solubility in water (limits its transport in plasma and slow its diffusion across increased distances)

A

carbon dioxide is 20 times more soluble in water than oxygen

134
Q

carbon dioxide’s higher solubility means it is

A

less affected buy increased diffusion distances, often resulting in normal arterial PCo2, even when arterial PO2 is low in conditions like pulmonary edema

135
Q

oxygen and carbon dioxide transport in the blood involves gases dissolving in

A

plasma, but red blood cells (erythrocytes) play a crucial role in transporting oxygen to due to hemoglobin

136
Q

mass flaw is defined as

A

the amount of a substance moving per minute (mass flow = concentration * volume flow)

137
Q

fick’s law of diffusion combine mass flow and mass balance equations to relate oxygen consumption, and blood oxygen content

A

QO2 = CO (arterial oxygen content - venous oxygen content)

138
Q

oxygen transport in the blood consists of two components:

A

oxygen dissolved in plasma (PO2) and oxygen bound to hemoglobin

139
Q

total blood oxygen content is the sum of

A

dissolved oxygen and oxygen bound to hemoglobin

140
Q

over 98% of oxygen is transported by

A

hemoglobin

141
Q

hemoglobin

A

is an oxygen binding protein in RBC that binds reversely to oxygen (is is a tetramer with four globular protein chains)

142
Q

each chain can bind one oxygen molecule, allowing one

A

hemoglobin molecule to bind up to four oxygen molecules

143
Q

oxyhemoglobin

A

hemoglobin bound to oxygen

144
Q

the hemoglobin binding reaction is

A

Hb + O2 = HbO2, and increase in O2 shifts the rxn to the right producing more HbO2

145
Q

in the blood, free oxygen available to bind to hemoglobin is dissolved oxygen,

A

indicated by the PO2 of plasma

146
Q

high altitude pulmonary edema (HAPE) is a severe illness and the major cause of death from altitude sickness characterized by

A

high pulmonary arterial pressure, extreme SOB and sometimes a productive cough with pink, frothy fluid

147
Q

treatment for HAPE involves

A

immediate relocation to a lower altitude and administration of oxygen

148
Q

oxygen transfer to the body’s cell occurs rapidly, and reaches equilibrium, with the

A

PO2 of the cells determining the amount of oxygen unloaded from hemoglobin

149
Q

the amount of oxygen that binds to hemoglobin depends on the partial pressure of oxygen (PO2) in

A

the plasma and the number available hemoglobin (Hb) binding sites in RBC

150
Q

Plasma PO2 is the primary factor determining the

A

percent saturation of hemoglobin, which is the percentage of available Hb binding sites occupied by oxygen

151
Q

arterial PO2 is influenced by the

A

composition of inspired air, the alveolar ventilation rate and the efficiency of gas exchange from alveoli to blood

152
Q

the number of oxygen binding sites can be estimated by counting the RBC and quantifying hemoglobin per cell or

A

measuring blood hemoglobin content

153
Q

blood transfusions are ideal for replacing lost

A

hemoglobin but in emergencies, saline infusions can only replace blood volume, not oxygen transport capacity

154
Q

percent saturation of hemoglobin is calculated as

A

(amount of O2 bound/maximum that could be bound) *100

155
Q

at normal alveolar and arterial PO2 (100 mmHg) hemoglobin is

A

98% saturated. The curve flattens at PO2, levels about 100mmHG indicating minor changes in saturation with large changes in PO2

156
Q

hemoglobin is not 100% saturated until PO2 reaches nearly

A

650 mmHg which is much higher than normal physiological conditions

157
Q

hemoglobin remain over 90% saturated as long as PO2 is above

A

60mmHg

158
Q

blood leaving systemic capillaries at PO2 at 40 mmHg is still

A

75% saturated

159
Q

what factors affect hemoglobin’s oxygen binding affinity, altering HbO2 saturation curve

A

plasma pH, temperature, and PCO2

160
Q

decreased pH, increased temperature or increased CO2

A

decrease hemoglobin’s affinity for oxygen

161
Q

During maximal exertion, anaerobic metabolism increases H+ concentration, lowering pH,

A

decreasing hemoglobin’s oxygen affinity, and shifting the saturation curve to the right. This is known as the Bohr effect.

162
Q

2,3-Bisphosphoglycerate (2,3-BPG) production increases during chronic hypoxia, lowering hemoglobin’s oxygen affinity and

A

shifting the saturation curve to the right. High altitude and anemia are conditions that increase 2,3-BPG production.

163
Q

fetal hemoglobin (HbF) has a higher oxygen binding affinity than adult hemoglobin due to its

A

gamma protein chains, facilitating oxygen transfer from maternal to fetal blood in the placenta. After birth, HbF is replaced by adult hemoglobin

164
Q

gas transport in the blood involves both oxygen delivery to cells and

A

carbon dioxide removal from cells

165
Q

carbon dioxide is a

A

by product of cellular respiration and must be exerted to prevent toxicity

166
Q

elevated PCO2 can cause

A

acidosis, a pH disturbance that can denature proteins and interfere with hydrogen bonding, it can depress CNA function leading to confusion, coma or death

167
Q

CO2 is more soluble in body fluids than oxygen but cells produce more

A

CO2 than can dissolve in plasma (70% of CO2 is converted to bicarbonate ion)

168
Q

bicarbonate ions then dissolve in the

A

plasma

169
Q

the conversion of carbon dioxide to bicarbonate ions serves two main purposes:

A

it provides an additional way to transport CO2 from cells to lungs and acts as a buffer for metabolic acids, helping stabilize the body’s pH

170
Q

the rapid production of HCO-3 depends on the

A

enzyme carbonic anhydrase (CA) which is concentrated in RBC

171
Q

dissolved in CO2 in the plasma diffuses into RBC, where it reacts with

A

water in the presence of carbonic anhydrase to form hydrogen ion (H+) and a bicarbonate ion (HCO-3)

172
Q

the reaction is reversible ans follow the law of mass action, the enzyme combine OH- directly with

A

CO2 to form bicarbonate

173
Q

two mechanisms remove free H+ and HCO-3:

A
  1. bicarbonate leaves the RBC on an antiport protein in a process known as the chloride shift (exchanging HCO-3 for Cl-)
  2. the transfer of HCO-3 into the plasma makes this buffer available to moderate pH changes caused by metabolic acids
174
Q

bicarbonate is the most important

A

extracellular buffer in the body

175
Q

hemoglobin in RBC acts as

A

a buffer by binding hydrogen ions forming HbH. it helps prevent significant changes in the body’s pH levels

176
Q

elevated blood PCO2 can overwhelm the hemoglobin buffer, leading to

A

excess H+ in the plasma

177
Q

excess K+ in the plasma results in

A

respiratory acidosis, a condition where the blood becomes too acidic

178
Q

most carbon dioxide entering RBC is converted to bicarbonate ions, but about 23% binds

A

directly to hemoglobin (at exposed amino groups forming carbaminohemoglobin)

179
Q

the presence of carbon dioxide and hydrogen ions decreases

A

hemoglobin’s affinity for oxygen, facilitating the formation of carbaminohemoglobin

180
Q

the increase in plasma pH enhances

A

oxygen binding hemoglobin in the lungs, even when PO2 is decreased

181
Q

CO2 diffuses from the blood into

A

alveoli, this causes plasma PCO2 to decrease dissolving CO2 to leave RBC

182
Q

the chloride shift reverses, allowing HCO-3 to move

A

back into RBC and convert to CO2 and water

183
Q

oxygen diffuses from the alveoli into the plasma and then back

A

into RBC, white it binds to hemoglobin, increasing oxygen transport capacity

184
Q

at the cells, O2 diffuses from the plasma into the cells due to

A

lower PO2 causing hemoglobin to release O2

physio (6 decks)

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