Respiratory system
DR– NOHA ELSAYED
2015---2016
The Thorax
Chest
• Formed by:
– 12 thoracic vertebrae (T1 to T12)
– 12 pairs of ribs
• Protects organs within the thorax
The Thorax
– Upper seven pairs of ribs (true ribs)
– Eighth, ninth, and tenth ribs (false ribs)
– Remaining two pairs of ribs (floating ribs)
The Thorax
• Midline of the chest is
the sternum.
• Superior border formed
by the jugular notch
• Sternum has three
components
The Thorax
• Largest structures in the thoracic
cavity are the:
– Heart (directly behind sternum)
– Lungs
– Great vessels
The Respiratory System: Anatomy
The Upper Airway
• Nasopharynx and oropharynx
connect to form pharynx
– Opens into nose and mouth
anteriorly
– Joins below the larynx
• Voice box
-Important to swallowing
• Located anteriorly and at
midline
• Includes:
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Nose
Mouth
Tongue
Jaw
Oral cavity
Larynx
Pharynx
The Upper Airway
• Nasopharynx and nasal passages (including
turbinates) warm, filter, and humidify air.
– Nasal mucous lines the nasal cavity.
• Air that enters through the mouth is less moist than
air that enters through the nose.
The Upper Airway
• Esophagus and trachea are at bottom of
pharynx
– Food and liquids pass through the esophagus.
– Air and other gases enter the trachea.
• Epiglottis protects opening of the trachea
– Allows air, but not food, to enter airway
The Lower Airway
• Adam’s apple (thyroid cartilage)
– Immediately below is palpable cricoid cartilage.
– Below cricoid cartilage is trachea
• Main stem bronchi divide into secondary and
tertiary bronchi and, eventually, bronchioles.
– Each bronchiole divides into alveoli.
The Lower Airway
• The bronchial tree is branched airways
leading from the trachea to the alveoli
– Hilum is the point of entry for the
bronchi, vessels, and nerves into each
lung.
– Mainstem bronchi divide into secondary
bronchi.
Lungs
• Primary organs of breathing
– Right lung contains three lobes
– Left lung contains two lobes
• Lungs are surrounded by pleura.
– Visceral pleura covers lungs, folds back to become
the parietal pleura
Lungs
• Pleural space exists between
visceral and parietal pleura.
• Lungs receive blood when:
– Deoxygenated blood flows
from right ventricle via
pulmonary arteries
– Oxygenated blood returns
from the alveoli.
Muscles of Breathing
• Respiration consists of
ventilation.
• Diaphragm is primary
muscle.
– Has characteristics of
voluntary and involuntary
muscle
– Divides thorax from
abdomen
Muscles of Breathing
• Other muscles involved are:
– Intercostal muscles
– Abdominal muscles
– Pectoral muscles
• During inhalation, the diaphragm and
intercostal muscles contract.
Muscles of Breathing
• The diaphragm and intercostal muscles relax
during respiration.
– Intrapulomic pressure is increased.
– This phase is passive.
• Exhalation ends when intrapulomic pressure
equals atmospheric pressure.
The Respiratory System: Physiology
• Respiration
– Exchanges gases at the alveolo-capillary
membrane
• Ventilation
– Process of moving air in and out of lungs
Respiration
• Oxygen moves across membranes into
capillaries and attaches to hemoglobin.
– Carbon dioxide moves into the alveoli.
The Chemical Control of Breathing
• The respiratory center in
brainstem controls breathing.
– Sensors for carbon dioxide
level in blood and spinal
fluid
– Changing levels of carbon
dioxide in the blood affect
pH.
• Respiratory center
adjusts ventilation
accordingly
• When oxygen level falls,
hypoxic drive stimulates
breathing
– Hypoxic drive is a less
sensitive backup system
The Nervous System Control of Breathing
• The medulla oblongata controls autonomic
functions.
– Dorsal respiratory group: pacemaker for breathing
– Ventral respiratory group: helps provide forced
inspiration and expiration
The Nervous System Control of Breathing
• Tidal volume (TV):Is the amount of air inspired
during normal, relaxed breathing
• Residual volume
– Gas that remains in the lungs to keep them open
• Vital capacity
– Amount of air moved with maximum inspiration
and expiration
• There is little to no alveoli in dead space.
Ventilation
• In addition to respiratory rate, you must assess
the depth of each breath.
• Minute volume provides a more accurate
determination of effective ventilation.
– Minute volume = Respiratory rate)12-20) × Tidal
volume
Characteristics of Normal Breathing
• Adequate tidal volume
• Regular rhythm or
pattern of inhalation and
exhalation
• Good audible breath
sounds on both sides of
chest
• Regular rise and fall
movement on both
sides of chest
• Movement of abdomen
• Silent and effortless
Inadequate Breathing Patterns in
Adults
• Labored breathing
• Less than 12 breaths/min or
more than 20 breaths/min
• Muscle retractions
• Pale or cyanotic skin
• Cool, clammy skin
• Tripod position (one sits or stands
leaning forward and supporting the upper
body with hands on the knees or on another
surface) indicate respiratory distress.
Inadequate Breathing Patterns in
Adults
• Patient may appear to be breathing after
normal respiration stops.
– Agonal gasps occur when the respiratory center in
the brain continues to send signals to the
breathing muscles.
• Assist ventilations of these patients.