Respiratory System Pt. II

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Respiratory System Pt. II

• Thomas Ackerman
• Juyoung Jang
• Liezel Riego

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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.

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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

• Respiratory Medium source of O2
• Air or and water
• Respiratory Surface where gases are exchanged
  with the surrounding environment
• Animals move O2 and CO2 by passive transport
  (diffusion-higher 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

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Mammalian respiration

• 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)

• 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
• 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
• Insects
• Tracheal system air tubes branching through body
• Folded internal respiratory surface
• Trachae opens outside
• Open circulatory system

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Other Animals (NOT mammals)

• Birds
• 8 or 9 airsacs and lungs
• Bellows keeping air flowing
• Not to be confused with alveolar sacs
• 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

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Marine Mammals

• What happens when respiratory medium is not
  accessible continuously?
• Weddell seal (and other diving mammals)
• Ability to store large amounts of O2
• 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
• Stores 24L of blood
• High concentration of myoglobin (oxygen-storing
  protein) in muscles
• 25 of O2 in muscle, 13 in humans
• 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

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Breathing ventilates the lungs

• Control of breathing
• 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

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Control of breathing (Cont.)

• 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

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Respiratory pigments bind and transport gases

• 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

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The Bohr Shift

• 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

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Carbon Dioxide Transport

• Other Functions for Hemoglobin
• Helps transport CO2
• Assists in buffering- prevents harmful changes in
  blood pH
• 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

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Carbon Dioxide Transport (Cont.)

• 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

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Pressure and Ventilation

• 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)

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Gas exchange at High Altitude (HL)

• 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
• 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

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Gas exchange at High Altitude (Cont.)

• 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
• 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

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Changes in the respiratory system

• At birth
• Before delivery, fetal lungs are fluid-filled and
  collapsed.
• At first breath, lungs inflate and never collapse
  completely thereafter.
• 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.

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Asthma

• 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

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Study Questions

• 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 hearts
  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.

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Suggested Answers

• 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.
• gt CO2 lt 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
  highergtlower 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