Transcript Respiratory System Pt2

Respiratory System Pt. II
Thomas Ackerman
Juyoung Jang
Liezel Riego
Quick Review
– 6.4.1: Distinguish between ventilation, gas
exchange, and cell respiration.
– 6.4.2: Explain the need for a ventilation
system.
– 6.4.3: Describe the features of the alveoli that
adapt them to gas exchange.
– 6.4.4: Draw and label a diagram of the
ventilation system, including trachea, lungs,
bronchi, bronchioles, and alveoli.
Functions of respiratory system
Providing an area for gas exchange
between air and circulating blood
 Moving air to and from exchange surfaces
 Protecting respiratory surfaces from
environmental variations
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Organization of the respiratory
system
Includes the nose, nasal cavity, pharynx,
larynx, trachea, bronchi, bronchioles, and
alveoli
 Respiratory tract: carries air to and from
alveoli
 Upper respiratory tract: filters and
humidifies incoming air
 Lower respiratory tract: gas exchange
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6.4.5: Mechanisms of Ventilation
To inhale, the diaphragm contracts and flattens and the external
intercoastal muscles also contract and cause the ribcage to expand and
move up.
– The diaphragm contracts drops downwards. Thoracic volume increases,
lungs expand, and the pressure inside the lungs decreases, so that air
flows into the lungs in response to the pressure gradient.
– These movements cause the chest cavity to become larger and the
pressure to be smaller, so air rushes in from the atmosphere to the
lungs.
 To exhale, the diaphragm relaxes and moves up. In quiet breathing, the
external intercoastal muscles relax causing the elasticity of the lung tissue
to recoil.
– In forced breathing, the internal inercoastal muscles and abdominal
muscles also contract to increase the force of the expiration.
– Thoracic volume decreases and the pressure inside the lungs increases.
Air flows passively out of the lungs in response to the pressure
gradient. The ribs to move downward and backward causing the chest
cavity to become smaller in volume and the pressure increases pushing
air out of the lungs into the atmosphere. (From AP Edition Biology)
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Gas exchange occurs across
specialized respiratory surfaces
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Respiratory Medium: source of
O2
– Air or and water
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Respiratory Surface: where
gases are exchanged with the
surrounding environment
– Animals move O2 and CO2 by
passive transport (diffusionhigher concentration to lower
concentration)
– Rate of diffusion is
proportional to the surface
area where diffusion occurs
and inversely proportional to
the square of the distance of
movement
– Thin and large surface area,
maximize gas exchange
Mammalian respiration
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Negative pressure
breathing: pulling air
instead of pushing it out
into the lungs.
– Lung volume increases as
rib muscles and diaphragm
contract
Tidal volume: Volume of
air inhalation
 Vital capacity: Max t.v. in
forced breathing
 Residual volume: amount
of air remaining after
forced breathing
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Other Animals (NOT mammals)
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Fish
– Gills: outfoldings of body surface extended in water
 Helps ventilation process: increasing flow of respiratory medium
over the respiratory surface
 Countercurrent exchange: makes it possible to transfer O2 to the
blood in water
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Insects
– Results in diffusion gradient for O2 over entire length of capillaries in
gills
– As blood moves through gill capillaries, loaded with O2, even through
against concentration gradient
– More than 80% in O2 in water is able to be diffused
– Tracheal system: air tubes branching through body
 Folded internal respiratory surface
– Trachae – opens outside
– Open circulatory system
Other Animals (NOT mammals)
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Birds
– 8 or 9 airsacs and lungs
 Bellows keeping air flowing
 Not to be confused with alveolar sacs
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Amphibians
– Positive pressure breathing: air is forced through lungs
– During cycle, muscles lower in oral cavity, drawing air through
nostrils
– Closed nostrils and mouth, floor of oral cavity rises
– Air is forced down trachea
– Elastic recoil of lungs and compression of muscular body wall
force air back out of the lungs
Marine Mammals
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What happens when respiratory
medium is not accessible continuously?
Weddell seal (and other “diving”
mammals):
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Ability to store large amounts of O2
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Twice as much per kg of body mass as
humans
5% in lungs, 70% in blood
Twice as much blood volume per kg of
body mass as humans
Huge spleen
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Stores 24L of blood
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25% of O2 in muscle, 13% in humans
High concentration of myoglobin
(oxygen-storing protein) in muscles
Swim with little muscular effort,
buoyancy
Heart rate and O2 consumption rate
decrease while diving
Blood supply to most muscles either
restricted or shut down completely
Breathing ventilates the lungs
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Control of breathing
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Breathing control centers: medulla oblongata and pons.
Pons sets basic breathing rhythm.
Sensors in aorta and carotid arteries monitor O2 and CO2 concentrations
Negative-feedback mechanism prevents lungs from over-expanding.
Medulla regulates breathing activity in response to pH changes of tissue
fluid (cerebrospinal).
 CO2 diffuses from blood to fluid, reacts with water and carbonic acid,
lowering pH
– Increases depth and rate of breathing
– Excess CO2 released through exhalation
– This happens during exercise
– O2 concentrations have little effect
– When O2 is extremely depressed (high altitudes), O2 sensors in aorta and carotid
arteries in neck send signals to breathing control centers
 Increases breathing rate
– Normally, rise in CO2 concentration accompanies fall in O2 concentration
Control of breathing (Cont.)
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Hyperventilation: tricking the breathing
center
– Excessive, deep, rapid breathing purges blood
of too much CO2
– Breathing center temporarily stops sending
impulses to rib muscles and diaphragm
– Breathing stops until CO2 levels increase (or
O2 levels decrease) enough so that the
breathing center turns back on
Respiratory pigments bind and
transport gases
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Oxygen has low solubility in water and in blood
Respiratory pigments: transport gases and help buffer
the blood
Greatly increase the amount of O2 the blood can carry
Hemoglobin - An iron containing protein in red-blood cell
that reversibly binds oxygen (“reversibly” just means
loading oxygen in the lungs and unloading it in the rest
of the body)
– Four protein subunits with iron in the middle of each subunit
– Each hemoglobin can bind to four molecules of O2
– Binding of O2 to once subunit causes the other three to change
their shape slightly
The Bohr Shift
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An effect that releases
oxygen by hemoglobin
Lowers the affinity for
oxygen because of drop
in pH and an increase in
partial pressure
– This causes the hemoglobin
to release more oxygen
which can be used for
cellular respiration
Carbon Dioxide
Transport
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Other Functions for Hemoglobin
– Helps transport CO2
– Assists in buffering- prevents
harmful changes in blood pH
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Process of Transportation
– CO2 diffuses into red blood cells
(90%) and plasma(7%)
– Some CO2 is picked up by
hemoglobin but most react in
water forming carbonic acid
(H2CO3)
– Carbonic acid dissociates into a
Hydrogen ion (H+) and
bicarbonate ion (HCO3-)
– Hemoglobin binds most of the H+
preventing it from acidifying the
blood and starting the Bohr Shift
Carbon Dioxide
Transport (Cont.)
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The carbonic acid (H2CO3) diffuses
into the plasma
Blood flows through the lungs so
the whole process is rapidly
reversed
– Diffusion of CO2 out of the
blood shifts the chemical
equilibrium in favor of the
conversion of bicarbonate ion
(HCO3-) to CO2
Bicarbonate ion (HCO3-) diffuses
from plasma into the red blood
cells
– This then combines with a
hydrogen ion (H+) to form
(H2CO3) , a carbonic acid
Carbonic acid is converted back to
CO2 and water
CO2 is then unloaded into the
alveolar space which then will be
expelled during exhalation
Pressure and Ventilation
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The direction of airflow is determined by the relation of
atmospheric pressure and intrapulmonary pressure
Intrapulmonary pressure is the pressure inside the
alveoli
Respiratory pressure
Low when you are relaxed and breathing quietly
Drops when you inhale
Increases when you exhale
Atmospheric pressure decreases with increasing
altitude and so do the partial pressure of gases
including oxygen
Partial pressure: measure of the concentration of one gas in a
mixture of gases; pressure exerted by particular gas in a
mixture of gases (pressure exerted by oxygen in air)
Gas exchange at High Altitude (HL)
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Partial air pressure of oxygen at high altitude is
lower than at sea level
– Effects
 Hemoglobin may not become fully saturated as it
passes through the lungs
 tissues of the body may not be adequately supplied
with oxygen
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Mountain Sickness
– with muscular weakness, rapid pulse, nausea and
headaches
– can be avoided by ascending gradually to allow the
body to acclimatize to high altitude
Gas exchange at High Altitude (Cont.)
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During acclimatization the ventilation rate increases
– Extra red blood cells are produced, increasing the hemoglobin
content of the blood
– Muscles produce more myoglobin and develop a denser
capillary network
– These changes help to supply the body with enough oxygen
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Some people who are native to high altitude show other
adaptations:
– a high lung capacity with a large surface area for gas
exchange
– larger tidal volumes and hemoglobin with an increased
affinity for oxygen
Changes in the respiratory
system
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At birth
– Before delivery, fetal lungs are fluid-filled and
collapsed.
– At first breath, lungs inflate and never collapse
completely thereafter.
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Aging:
– Less efficient in elderly
 Elastic tissue deteriorates, lowering the vital capacity of
the lungs.
 Movements of the chest are restricted by arthritic
changes and decreased flexibility of costal cartilages.
 Some degree of emphysema is generally present.
Asthma
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Chronic long term lung
disease that inflames and
narrows airways
The muscles around the
bronchi tighten which
causes less air to flow to
your lungs
Causes-pollen, pets, dust
mites, fungi etc.
– Being “too clean” causes
the immune system to
react against harmless
substances
Study Questions
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Why is the position of lung tissues within the body an advantage for
terrestrial animals?
Explain how countercurrent exchange maximizes the ability of fish gills to
extract dissolved O2 from water
How does an increase in the CO2 concentration in the blood affect the pH
of cerebrospinal fluid?
A slight decrease in blood pH causes the heart’s pacemaker to speed up.
What is the function of this control mechanism?
How does breathing differ in mammals and birds?
What determines whether O2 or CO2 diffuse into or out of the capillaries in
the tissues and near the alveolar spaces? Explain.
How does the Bohr shift help deliver O2 to very active tissues?
Carbon dioxide within red blood cells in the tissue capillaries combines with
water, forming carbonic acid. What causes the reverse of this reaction in red
blood cells in capillaries near the alveolar spaces?
Describe three (3) adaptations that enable Weddell seals to stay
underwater much longer than humans can.
Suggested Answers
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If lungs extended into environment, dry out, diffusion would stop
Results in diffusion gradient for O2 over entire length of capillaries in gills,
opposite flow allows for O2 loading, despite against concent. grad.
> CO2 = < pH
Increases heart rate increases rate at which CO2 is delivered to lungs,
where CO2 is removed.
Air passes through lungs in one direction in birds; direction reverses in
mammals between inhalation and exhalation.
Differences in partial pressure; gases diffuse higher>lower partial press.
Causes hemoglobin to release more O2 at lower pH, in vicinity of tissues w/
high resp. rates and CO2 release.
Decrease in CO2 concent. in plasma as it diffuses into alveolar spaces
causes carbonic acid within RBC to break down, yielding CO2, diffuses into
plasma
Blood volume relative to body mass; larger spleen; more myoglobin in
muscles; heart rate and metabolic rate decrease during dives