the respiratory system Flashcards
(186 cards)
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)
2
Q
external respiration involves four processes
A
- exchange of air between the atmosphere and lungs (ventilation), including inspiration (inhalation) and expiration (exhalation).
- exchange of O2 and CO2 between lungs and blood
- Transport of O2 and CO2
- Exchange of gases between blood and cells
3
Q
external respiration requires coordination between
A
the respiratory and cardiovascular systems
4
Q
the respiratory system includes
A
- conducting system of airways leading to the lungs
- alveoli and pulmonary capillaries for gas exchange
- bones and muscles of the thorax and abdomen aiding in ventilation
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)
6
Q
the thorax is enclosed by the
A
spine, rib cage, and associated muscles, collectively known as the thoracic cage
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.
8
Q
the diaphragm is
A
a dome shaped sheet of skeletal muscle
9
Q
two sets of intercostal muscles, internal and external
A
connect the 12 pairs of ribs
10
Q
additional muscles, the sternocleidomastoids and the scalenes extend from
A
the head and neck to the sternum and the first two ribs
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)
12
Q
the esophagus, thoracic blood vessels and nerves pass
A
between the pleural sacs.
13
Q
the lungs are light, spongy organs primarily filled with
A
air spaces and nearly fill the thoracic cavity, resting on the diaphragm
14
Q
the bronchi are semi-rigid airways that connect the lungs to the
A
trachea
15
Q
each lung is encased in a
A
double walled pleural sac, with membranes lining the thorax and covering the lung surface
16
Q
the pleural membranes contain elastic connective tissue and numerous capillaries, held together by a
A
thin film of pleural fluid
17
Q
pleural fluid
A
creates a moist, slippery surface for membrane movement and holds the lungs against the thoracic wall
18
Q
the fluid bond between pleural membranes keeps the lungs partially
A
inflated and adhered to the thoracic cage, even at rest
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
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.
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
22
Q
within the lungs, the bronchi branch repeatedly into
A
smaller bronchi, which are also semirigid tubes supported by cartilage
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
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
25
the total cross sectional area is the lowest in the upper respiratory tract and greatest in the
bronchioles, similar to the increase in cross sectional area from the aorta to the capillaries in the circulatory system
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the velocity of air flow is inversely proportional to the total cross-sectional area of the airways,
meaning it is the greatest in the upper airways and slowest in the terminal bronchioles
27
the upper airways and bronchi condition air it reaches the alveoli by
warming it to body temperature (37°C), adding water vapor to achieve 100% humidity, and filtering out of foreign material
28
breathing through the nose is more effective at warming and moistening air than
breathing through the moth, which can cause chest discomfort in cold weather
29
air filtration occurs in the trachea and bronchi, which are lined with
ciliated epithelium. The cilia are bathed in watery saline layer produced by epithelial cells
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the saline layer is created when Cl- is secreted into the lumen by
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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the CFTR channel, an anion channel on the apical surface of the epithelium is crucial for this process
malfunction of this CFTR channel causes cystic fibrosis
32
the mucociliary escalator is a mechanism where a sticky mucus layer traps
inhaled particles larger than 2 macrometers, and cilia move the mucus toward the pharynx
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mucus contains immunoglobulins that disable
pathogens and can be expectorated or swallowed with stomach acid and enzymes destroying remaining microorganisms
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a watery saline layer beneath the mucus is essential for the
mucociliary escalator's function
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in cystic fibrosis, inadequate ion secretion reduces fluid movement, trapping
cilia in thick mucus, preventing clearance and leading to recurrent lung infections
36
alveoli
are air filled sacs at the ends of terminal bronchioles, primarily responsible for gas exchange with the blood
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alveoli are composed of a
single layer of epithelium, with two types of epithelial cells: type I and type II
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type 1 alveolar cells cover about
95% of the alveolar surface area and are very thin to facilitate rapid gas diffusion
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type II alveolar cells are
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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alveoli walls lack muscle fibers to avoid obstructing
gas exchange, but connective tissue with elastin and collagen fibers provides elastic recoil
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the extensive network of capillaries around the alveoli highlights
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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the pulmonary circulation starts with the
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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oxygenated blood returns from the lungs to the
left atrium via the pulmonary veins
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pulmonary circulation hold about 0.5 liters of blood,
or 10% of the total blood volume, with 75mL in the capillaries where gas exchange occurs
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the lungs receive the entire cardiac output of the right ventricle, which is 5L/min, resulting
in a higher blood flow rate through the lungs compared to other tissues
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despite the high flow rate, pulmonary blood pressure is low
averaging 25/8 mmHg compared to systemic pressure of 120/80 mmHg
47
the right ventricle pumps with less force due to the
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
48
net hydrostatic pressure in pulmonary capillaries is
low, minimizing fluid filtration into the interstitial space
49
the lymphatic system effectively removes
filtered fluid, keeping lung interstitial fluid volume minimal
50
the short distance between the alveolar air space and the capillary endothelium allows
for rapid gas diffusion
51
respiratory air flow and blood flow are similar because both involve
the movement of fluid, but differ as blood is non-compressible liquid and air is a compressible gas
52
gas laws govern the behavior of gases in air, which is crucial fro the exchange of
air between the atmosphere and the alveoli
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blood pressure and environmental air pressure are reported in millimeters of mercury
respiratory physiologists may also use centimeters of water or kiloPascals for gas pressures
54
conversion factors:
1 mmHg = 1.36cm H2O
760 mmHg = 101.325 kPa
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at sea level, normal atmospheric pressure is 760mmHg but it is often
designated as 0 mmHg to simplify comparisons of pressure differences during ventilation, regardless of attitude
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the atmosphere is a mixture of
gases and water vapor
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dalton's law states that
the total pressure of a gas mixture is the sum of the pressures of the individual gases
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in dry air, at 760 mmHg, 78% of the pressure is due to
N2 and 21% is due to O2
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the partial pressure of a gas (Pgas) is
the pressure exerted by that gas in a mixture
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partial pressure is determined by
the gas's relative abundance and is independent of molecular size of mass
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water vapor in the air affect the partial pressures of other gases by
diluting their contribution to the total pressure
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air flow occurs due to
pressure gradients, moving from areas of higher pressure to areas of lower pressure
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in ventilation, air moves between the external environment and the lungs down pressure gradients created by
thoracic movements during breathing
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diffusion of gases occurs down concentration (partial pressure) gradients, with oxygen moving from areas of
higher partial pressure (PO2) to areas of lower partial pressure
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this diffusion is crucial for the exchange of oxygen and carbon dioxide between
alveoli and blood and from blood to cells
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gas pressure in a sealed container is due to
collisions of gas molecules with the container walls and each other
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reducing the container size increases
collision frequency and pressure
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boyle's law describes the inverse relationship between
pressure and volume: P1V1=P2V2
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in the respiratory system, changes in chest cavity volume during ventilation create
pressure gradients that drive airflow
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increased chest volume lowers alveolar pressure causing
air to flow into the lungs
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decreased chest volume raises alveolar pressure causing
air to flow out of the lungs
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air movement in the respiratory system is
bulk flow, involving the entire gas mixture
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a single respiratory cycle includes
one inspiration (inhalation) followed by one expiration (exhalation)
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pulmonary function is assessed by measuring
the volume of air moved during quiet and maximum effort breathing
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a spirometer us used to measure
the volume of air moved with each breath
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the air moved during breathing is divided into four lung volumes:
tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume
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tidal volume (Vt)
is the volume of air that moves during a single inspiration or expiration averaging about 500mL during quiet breathing
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inspiratory reserve volume (IRV)
is the additional volume you can inspire above the tidal volume
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expiratory reserve volume (ERV)
is the amount of air forcefully exhaled after a normal expiration
79
residual volume (RV)
is the volume of air remaining in the lungs after maximal exhalation
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capacity
the sum of two or more lung volumes
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vital capacity (VC)
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
total lung capacity (VC) is
the sum of the inspiratory reserve volume and residual volume
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inspiratory capacity is the
sum of tidal volume and inspiratory reserve volume
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function residual capacity
is the sum of expiratory reserve volume and residual volume
85
the thoracic cage muscles and diaphragm act as the
pump for respiratory system, expanding the lungs when they contract
86
the lungs are held to the chest wall by
pleural fluid
87
primary muscles for quit breathing include the
diaphragm, external intercostals, and scalenes
88
forced breathing involves addition chest and
abdominal muscles, used during activities like exercise, playing wind instruments, and blowing up balloons
89
air flow for the respiratory tract follows the equation
flow is directly proportional to pressure/resistance, meaning air flows due to a pressure gradient (delta P) and decreases with increased resistance (R).
90
for air to move into the alveoli, lung pressure must be
lower than atmospheric pressure as per Boyle's law, which states that an increase in volume leads to a decrease in pressure
91
during inspiration, thoracic volume increases due to the
contraction of the diaphragm and rib cage muscles. the diaphragm moves downward about 1.5 cm contributing 60-75% of inspiratory volume change
92
the external intercostal and scalene muscles contract, pulling the
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
as thoracic volume increases, pressure decreases,
allowing air to flow into the lungs
94
the inspiratory muscles include
the diaphragm, external intercostals, and scalenes, with their contribution varying based on the type of breathing
95
during the brief pause between breaths, alveolar pressure equal
atmospheric pressure (0mmHg at A1)
96
when alveolar and atmospheric pressures are equal,
no air flow occurs
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inspiratory muscles contract, increasing thoracic volume and decreasing
alveolar pressure by about 1 mmHg below atmospheric pressure
98
air flows into the alveoli due to the
pressure difference
99
alveolar pressure reaches its lowest value halfway through
inspiration as thoracic volume changes faster than air can flow
100
as air continues to flow in,
alveolar pressure increases until the thoracic cage stops expanding
101
air movement continues briefly under alveolar pressure
equalizes with atmosphere pressurea
102
at the end of inspiration, lung volume is at its maximum,
and alveolar pressure is equal to atmospheric pressure
103
breathing involves the bulk flow of air into and out of the lungs, with gases like
oxygen and CO2 diffusing from the alveoli into the blood
104
diffusion is the movement of molecules from
higher to lower concentration. respiratory physiologists use partial pressures to express plasma gas concentrations
104
gases move from regions of higher partial to
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
oxygen diffuses from the alveoli into the
capillaries reaching equilibrium with arterial blood leaving the lungs at Po2 of 100 mmHg
106
in tissue capillaries, the gradient reverses, cells use oxygen for oxidative phosphorylation, with intracellular PO2 averaging 40mmHg. oxygen diffuses from plasma into
cells, and venous blood has the same PO2 as the cells
107
PcO2 is higher in tissues than in
systemic capillary blood due to Co2 production during metabolism. Cellular PcO2 is about 46 mmHg compared to arterial plasma PCO2 of 40 mmHg
108
CO2 diffuses out of cells into capillaries, reaching equilibrium with systemic venous blood averaging a PCO2 of
46 mmHg
109
at the pulmonary capillaries, venous blood with PCO2 at 46mmHg releases CO2 into the
alveoli, which have a PCO2 of 40 mmHg. Blood leaves the alveoli with a PCO2 of 40 mmHg
110
The electron transport system is directly associated with
O2 consumption, while the citric acid cycle is directly associated with CO2 production
111
the efficiency of alveolar gas exchange is influenced by several variables, which determine whether
arterial blood gases are normal
112
adequate oxygen must reach the alveoli,
a decrease in PO2 means less oxygen is available to enter the blood
113
problems can occur with the transfer of gases between the alveoli and
pulmonary capillaries
114
low alveolar PO2 can be caused by
low oxygen content in the inspired air or inadequate alveolar ventilation
115
altitude significantly affects atmospheric oxygen content due to
changes in partial pressure
116
as altitude increase, the partial pressure of oxygen (PO2)
in the air decrease
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water vapor pressure at 100% humidity remains
constant regardless of altitude, making its impact on total lung pressure more significant at higher altitudes
118
if the composition of inspired air is normal but but alveolar PO2 is low,
the issue is with alveolar ventilation
119
low alveolar ventilation or hypoventilation is characterized by
reduced volumes of fresh air entering alveoli
120
pathological changes leading to hypoventilation include:
- decreased lung compliance
- increased airway resistance
- CNS depression which slow ventilation rate and decreases depth
121
alveolar PO2 may be normal but arterial PO2 can be low due to
impaired oxygen transfer
122
oxygen transfer requires
diffusion across the barrier formed by type I alveolar cells and capillary endothelium
123
the diffusion rate is directly proportional to
surface area, concentration gradient, and barrier permeability
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diffusion rate is directly proportional to 1/ distance ^2
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in healthy individuals, the concentration gradient between alveoli and blood is the main factor affecting
gas exchange
126
pulse oximeter is a device that measures blood oxygen, how does it work
by measuring the light absorbance of hemoglobin at two different wavelengths
127
pulmonary diffusion distance is
normally small due to thin alveolar and endothelial cells and minimal interstitial fluid
128
pulmonary edema involves
interstitial fluid accumulation, increasing diffusion distance and impairing gas exchange
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increased pulmonary blood pressure disrupts
capillary filtration/reabsorption balance
130
elevated capillary hydrostatic pressure leads to
more fluid filtering out, potentially overwhelming lymphatic removal and causing pulmonary edema
131
gas exchange in the alveoli is influence by
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
higher gas pressure in causes gas to
leave the water (while higher gas pressure in air causes gas to dissolve into the water)
133
oxygen has low solubility in water (limits its transport in plasma and slow its diffusion across increased distances)
carbon dioxide is 20 times more soluble in water than oxygen
134
carbon dioxide's higher solubility means it is
less affected buy increased diffusion distances, often resulting in normal arterial PCo2, even when arterial PO2 is low in conditions like pulmonary edema
135
oxygen and carbon dioxide transport in the blood involves gases dissolving in
plasma, but red blood cells (erythrocytes) play a crucial role in transporting oxygen to due to hemoglobin
136
mass flaw is defined as
the amount of a substance moving per minute (mass flow = concentration * volume flow)
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fick's law of diffusion combine mass flow and mass balance equations to relate oxygen consumption, and blood oxygen content
QO2 = CO (arterial oxygen content - venous oxygen content)
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oxygen transport in the blood consists of two components:
oxygen dissolved in plasma (PO2) and oxygen bound to hemoglobin
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total blood oxygen content is the sum of
dissolved oxygen and oxygen bound to hemoglobin
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over 98% of oxygen is transported by
hemoglobin
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hemoglobin
is an oxygen binding protein in RBC that binds reversely to oxygen (is is a tetramer with four globular protein chains)
142
each chain can bind one oxygen molecule, allowing one
hemoglobin molecule to bind up to four oxygen molecules
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oxyhemoglobin
hemoglobin bound to oxygen
144
the hemoglobin binding reaction is
Hb + O2 = HbO2, and increase in O2 shifts the rxn to the right producing more HbO2
145
in the blood, free oxygen available to bind to hemoglobin is dissolved oxygen,
indicated by the PO2 of plasma
146
high altitude pulmonary edema (HAPE) is a severe illness and the major cause of death from altitude sickness characterized by
high pulmonary arterial pressure, extreme SOB and sometimes a productive cough with pink, frothy fluid
147
treatment for HAPE involves
immediate relocation to a lower altitude and administration of oxygen
148
oxygen transfer to the body's cell occurs rapidly, and reaches equilibrium, with the
PO2 of the cells determining the amount of oxygen unloaded from hemoglobin
149
the amount of oxygen that binds to hemoglobin depends on the partial pressure of oxygen (PO2) in
the plasma and the number available hemoglobin (Hb) binding sites in RBC
150
Plasma PO2 is the primary factor determining the
percent saturation of hemoglobin, which is the percentage of available Hb binding sites occupied by oxygen
151
arterial PO2 is influenced by the
composition of inspired air, the alveolar ventilation rate and the efficiency of gas exchange from alveoli to blood
152
the number of oxygen binding sites can be estimated by counting the RBC and quantifying hemoglobin per cell or
measuring blood hemoglobin content
153
blood transfusions are ideal for replacing lost
hemoglobin but in emergencies, saline infusions can only replace blood volume, not oxygen transport capacity
154
percent saturation of hemoglobin is calculated as
(amount of O2 bound/maximum that could be bound) *100
155
at normal alveolar and arterial PO2 (100 mmHg) hemoglobin is
98% saturated. The curve flattens at PO2, levels about 100mmHG indicating minor changes in saturation with large changes in PO2
156
hemoglobin is not 100% saturated until PO2 reaches nearly
650 mmHg which is much higher than normal physiological conditions
157
hemoglobin remain over 90% saturated as long as PO2 is above
60mmHg
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blood leaving systemic capillaries at PO2 at 40 mmHg is still
75% saturated
159
what factors affect hemoglobin's oxygen binding affinity, altering HbO2 saturation curve
plasma pH, temperature, and PCO2
160
decreased pH, increased temperature or increased CO2
decrease hemoglobin's affinity for oxygen
161
During maximal exertion, anaerobic metabolism increases H+ concentration, lowering pH,
decreasing hemoglobin's oxygen affinity, and shifting the saturation curve to the right. This is known as the Bohr effect.
162
2,3-Bisphosphoglycerate (2,3-BPG) production increases during chronic hypoxia, lowering hemoglobin's oxygen affinity and
shifting the saturation curve to the right. High altitude and anemia are conditions that increase 2,3-BPG production.
163
fetal hemoglobin (HbF) has a higher oxygen binding affinity than adult hemoglobin due to its
gamma protein chains, facilitating oxygen transfer from maternal to fetal blood in the placenta. After birth, HbF is replaced by adult hemoglobin
164
gas transport in the blood involves both oxygen delivery to cells and
carbon dioxide removal from cells
165
carbon dioxide is a
by product of cellular respiration and must be exerted to prevent toxicity
166
elevated PCO2 can cause
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
CO2 is more soluble in body fluids than oxygen but cells produce more
CO2 than can dissolve in plasma (70% of CO2 is converted to bicarbonate ion)
168
bicarbonate ions then dissolve in the
plasma
169
the conversion of carbon dioxide to bicarbonate ions serves two main purposes:
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
the rapid production of HCO-3 depends on the
enzyme carbonic anhydrase (CA) which is concentrated in RBC
171
dissolved in CO2 in the plasma diffuses into RBC, where it reacts with
water in the presence of carbonic anhydrase to form hydrogen ion (H+) and a bicarbonate ion (HCO-3)
172
the reaction is reversible ans follow the law of mass action, the enzyme combine OH- directly with
CO2 to form bicarbonate
173
two mechanisms remove free H+ and HCO-3:
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
bicarbonate is the most important
extracellular buffer in the body
175
hemoglobin in RBC acts as
a buffer by binding hydrogen ions forming HbH. it helps prevent significant changes in the body's pH levels
176
elevated blood PCO2 can overwhelm the hemoglobin buffer, leading to
excess H+ in the plasma
177
excess K+ in the plasma results in
respiratory acidosis, a condition where the blood becomes too acidic
178
most carbon dioxide entering RBC is converted to bicarbonate ions, but about 23% binds
directly to hemoglobin (at exposed amino groups forming carbaminohemoglobin)
179
the presence of carbon dioxide and hydrogen ions decreases
hemoglobin's affinity for oxygen, facilitating the formation of carbaminohemoglobin
180
the increase in plasma pH enhances
oxygen binding hemoglobin in the lungs, even when PO2 is decreased
181
CO2 diffuses from the blood into
alveoli, this causes plasma PCO2 to decrease dissolving CO2 to leave RBC
182
the chloride shift reverses, allowing HCO-3 to move
back into RBC and convert to CO2 and water
183
oxygen diffuses from the alveoli into the plasma and then back
into RBC, white it binds to hemoglobin, increasing oxygen transport capacity
184
at the cells, O2 diffuses from the plasma into the cells due to
lower PO2 causing hemoglobin to release O2
