Maintenance of the Human Body Part 3: The Respiratory System

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Maintenance of the Human BodyPart 3 The
Respiratory System

• Concepts chapter 24

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The respiratory system

• Body cells continually use O2 produce CO2 as a
  waste product.
• Respiratory system moves these 2 gases.
• Consists of
• Nose
• Pharynx
• Larynx
• Trachea
• Bronchi
• Lungs

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The respiratory systemstructures

• Nose fxns to filter moisten air. Also
  receptors for smell.
• Pharynx is posterior to nasal oral cavities.
  Its a passageway for air, food, voice resonance,
  houses tonsils.
• Larynx connects pharynx with trachea. Walls are
  composed of cartilage.

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The respiratory systemstructures
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The respiratory systemstructures

• Trachea is reinforced with C-shaped hyaline
  cartilage. Goes from larynx to level of 5th
  thoracic vertebrae. Then it branches.
• Bronchi are the 2 tubes that enter the right
  left lung.

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The respiratory systemstructures

• Trachea? primary bronchi ? secondary bronchi ?
  tertiary bronchi ? bronchioles ? terminal
  bronchioles

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The respiratory systemstructures

• Lungs are covered in double layer called pleural
  membrane. Consists of
• Parietal pleura
• Visceral pleura
• Pleural cavity is in btwn
• These membranes help to reduce friction.

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The respiratory systemstructures

• Each lung has a hilum which is the region through
  which the bronchi, pulmonary blood vessels,
  lymphatic vessels nerves enter and exit.
• Right lung is slightly larger.
• It has 3 lobes. Left has 2.

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The respiratory systemstructures

• At the end of each terminal bronchiole are
  clusters of alveoli.
• Alveoli have very thin, moist walls that are
  closely associated with capillaries.
• The walls also have dust cells which are
  phagocytic immune cells.

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The respiratory systemventilation

• Respiration the process of gas exchange. There
  are 3 parts
• Pulmonaryinhalation exhalation
• Externalexchange btwn alveoli capillaries (O2
  in to blood, CO2 out)
• Internalexchange btwn blood tissue cells (O2
  into tissue cells, CO2 out)

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The respiratory systemventilation

• Inhalation
• Diaphragm contracts flattens.
• Intercostal myos contract raise rib cage.
• (these first two actually occur at the same time)
• Volume of the thoracic cavity increases, so
  pressure inside decreases.
• Air moves in b/c pressure inside lungs is less
  than air pressure.

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The respiratory systemventilation
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The respiratory systemventilation

• Diaphragm decends 1cm during relaxed breathing
  10 cm during strenuous breathing.
• Accessory myos can elevate sternum upper ribs
  to increase thoracic volume even more.

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The respiratory systemventilation

• Exhalation
• Usually a passive process.
• There is elastic recoil of the thoracic
  structuresthey tend to spring back after being
  stretched.
• Diaphragm relaxes rises.
• Intercostal myos relax rib cage lowers.
• Thoracic cavity space decreases, air is forced
  out.

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Lung volumes
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The respiratory systemgas exchange

• Gases diffuse in out of alveoli vessels based
  on pressure differences.
• If oxygen has higher partial pressure in alveoli
  than in capillaries, it will diffuse into
  capillaries. The opposite is also true.

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The respiratory systemgas exchange

• Oxygen doesnt dissolve well in water.
• It must be carried in red blood cells by the
  protein hemoglobin.
• The higher the partial pressure of O2, the more
  saturated Hb is.

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The respiratory systemgas exchange

• pH can also affect the affinity of Hb for oxygen.
• Exercising tissues produce several metabolic
  acids.
• What does that do to Hbs ability to let go of
  the oxygen so it can diffuse into active tissues?

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The respiratory systemgas exchange
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The respiratory systemgas exchange

• CO2 is transported differently.
• Some is dissolved in blood plasma (non cellular
  part of blood)
• A little more is transported on Hb
• Most is transported as bicarbonate ion.

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The respiratory systemcontrol

• Cortical influences
• Cerebral cortex has connections with the
  respiratory center in medulla oblongata.
• You can voluntarily change your breathing
  pattern.
• Limited by build up of CO2 H.

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The respiratory systemcontrol

• Chemoreceptor regulation
• Chemoreceptors can sense changes in certain
  chemicals.
• An increase in CO2 causes a decrease in pH.
• Chemoreceptors detect this.
• Respiratory center sends signals to myo of
  inhalation exhalation.
• Breathing rate depth is increased.

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The respiratory systemcontrol

• Other factors affect respiration
• Emotional anxiety? ? rate
• Temperature
• ?Temp ? ? rate
• Sudden ?temp ?temporary apnea
• Painbrief apnea, then rate ?
• Airway irritation?apnea followed by cough or
  sneeze.

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The end