The respiration system

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The respiration system
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• The respiration system provides the rout by which
  the supply of O2 present in the atmospheric air
  gains entry to the body and it provide the rout
  of carbon dioxide CO2 .

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• The air breathed in moves through the air
  passages to reach the lungs , and then warmed or
  cooled to the body temperature , the blood
  provides the respiratory system for these gases
  between the lungs and the blood called (
  external respiration ) and between the lungs and
  cells called ( internal respiration ) .

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• The organs of the respiratory systems are
  includes ( nose , pharynx , larynx , trachea ,
  two bronchi , two lungs and the muscles of
  respiration -- intercostals muscles and the
  diaphragm ) page 93, fig 7-1 , 2

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• (1) Nose and nasal cavity
• The nasal cavity is the first of the
  respiratory organs and consist of large irregular
  cavity divided into two equal parts by a septum
  situation in the midline.

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• Posteriorly ---- formed by the perpendicular
  plate of the ethmoid bone and the
  vomer
• Anteriorly ---- consists of hyaline cartilage
  
• The roof ---- formed by cribriform plate of the
  ethmoid bone , sphenoid bone ,
  frontal bone , and the nasal
  bone
• The floor ---- formed by the roof of the mouth
  ( hard and soft palate
• Medial wall --- formed by the septum
• Lateral walls --- formed by the maxilla ethmoid
  and inferior conchae
• Posterior wall -- formed by the posterior wall
  of the pharynx .

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• Openings into the nasal cavity
• The anterior nares--- are the opening from the
  exterior to the nasal cavity
• The posterior nares--- are the opening from the
  nasal cavity into pharynx
• The sinuses cavities --- in the maxilla of face
• ( lateral wall ) and in the frontal and
  sphenoid of the cranium
  ( in the roof) and the ethmoid
  sinuses in the upper part of the
  lateral wall , which contain air
• The nasolacrimal ducts --- extend from the
  lateral walls of the nose to the
  conjuctival sacs of the eyes .

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• Note ------ the nose is lined with ciliated
  columnar epithelium which contains mucus
  secreting goblet cel

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• The function of the nose
• is begin the process by which the air is
  warmed , moistened and filtered , also the nose
  is the organ of the sense of the smell (
  olfactory function ).

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• (2) The pharynx ( page 94 , fig 7-7 )
• Is a tube 12 -14 cm . extends from the
  base of the skull to the 6th cervical vertebra ,
  it lies behind the nose , the mouth and the
  larynx and is wider at its upper end .

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• Structure in association with the pharynx
• Superiorly ---- the inferior surface of the base
  of the skull .
• Inferiorly ---- continuous with the oesophagus
• Anteriorly ---- incomplete wall because of the
  opening into the nose , mouth , and larynx
• Posteriorly ---- areolar tissue . involuntary
  muscle and the bodies of the first six cervical
  vertebrae

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• The pharynx is divided into three parts
• ( nasal , oral and laryngeal )
• 1) nasal part
• Lies behind the nose above the level of the soft
  palate .
• 2) oral part
• Lies behind the mouth and extending from below
  the level of the soft palate to the level of the
  third cervical vertebra .
• 3) laryngeal part
• Extends from the level of the third to the sixth
  cervical vertebrae

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• Structure
• The pharynx is composed of three layers of tissue
  
• 1) mucous membrane which lines the pharynx
• 2) fibrous tissue which forms intermediate layer
• 3) muscle tissue which consists of constrictor
  muscles of the pharynx , which play an important
  part in the swallowing

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• Note1 ---- the blood supply to the
  pharynx by facial artery .
• Note 2--- the nerve supply the pharynx
  by the vagus and gloss- pharyngeal
  nerves .

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• Functions
• 1) passing the air through the nasal and oral
  parts
• 2) passing the food through the oral and the
  laryngeal parts
• 3) moist and warmed the air
• 4) passing the air to the meddle ear for
  satisfactory hearing .
• 5) prevent micro organisms from entering the
  body by laryngeal tonsils and lymphatic
  tissue

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• (3) The larynx
• The larynx or ( voice box ) extended from
  the root of the tongue and the hyoid bone to the
  trachea , it lies in front of the laryngeal part
  of the pharynx at the level of the third , fourth
  , fifth and sixth cervical vertebrae , it grows
  larger in the male , which explains the
  prominence of the ( Adams apple ) and generally
  deeper voice

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• Structure in association with the larynx
• Superiorly ---- hyoid bone and the root of the
  tongue .
• Inferiorly ---- continuous with trachea .
• Posteriorly ---- laryngeal part of pharynx and
  cervical vertebrae .
• Laterally --- the lobes of the thyroid gland .

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• Structure ( page 96,97. figure 7 -
  8,9,10,11,12 )
• The larynx is composed of several
  irregularly shaped cartilages attached to each
  other includes .
• 1) thyroid cartelage ( 1) .------- hyaline
  cartilage
• 2) cricoid cartilage ( 1 ).------- hyaline
  cartilage
• 3) aretenoid cartilages (2) .------- hyaline
  cartilage
• 4) epiglottis ----- elastic fibrocartilage.

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• Note ----
• the blood supply to the larynx by
  superior and inferior laryngeal arteries , and
  drained by the thyroid vein and internal jugular
  vein
• Note ----
• the nerve supply the larynx by superior
  laryngeal and laryngeal nerve which branches to
  the vagus nerves

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• Functions
• 1) passing air between the pharynx and the
  trachea .
• 2) moist , filter and warmed the air .
• 3) the vocal cords produce sound of varying
  loudness and pitch .
• 4) help to ensures that the food passes into the
  oesophagus not into the lower
  respiratory passages during
  swallowing .

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• (4) The trachea ( page 98 ,figure 7 -14 )
• The trachea or windpipe is continuation
  of the larynx and extends to about the level of
  the fifth thoracic vertebra where it divides into
  the right and left bronchi , its approximately 10
  - 11 cm long and lies in the median plane in
  front of the oesophagus .

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• Structure in association with the trachea
• Superiorly --- the larynx
• Inferiorly ---- right and left bronchi
• Anteriorly ---- thyroid gland and arch of the
  aorta and the sternum ,
• Posteriorly ---- the oesophagus
• Laterally ---- lobes of thyroid gland and the
  lungs .

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• Structure
• The trachea is composed of form 16 - 20
  incomplete ( C- shape ) rings of hyaline
  cartilages situated one above the other .

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• Note1
• the blood supply to the trachea by the
  inferior thyroid and bronchial arteries and
  return by inferior thyroid vein into the
  brachiocephalic vein.
• Note2
• the nerve supply the trachea by laryngeal
  nerves and vagus nerve .

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• (5) The bronchi ( page 98, figure 7-15 )
• The right bronchus is a wider , shorter
  tube than the left it divides into three
  branches one of which passes to each lobe of the
  RT lung ,

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• The left bronchus is longer and narrower than the
  right , it divided into two branches in the lung
  , each branch goes to each lobe of the LT lung .

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• Structure
• It composed of the same tissues as the
  trachea , they become smaller by subdividing ,
  the bronchi are lined with ciliated columnar
  epithelium .

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• (6) the bronchioles , smaller air passages and
  alveoli ( page 99 , figure 7-16 )
• Structure
• There is no clear anatomical division
  between bronchi and bronchioles , the large r
  bronchioles are composed of muscle tissue ,
  fibrous tissue and elastic tissue with an inner
  lining of ciliated columnar epithelium ,

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• The minute bronchioles known as the terminal
  bronchioles , branch to form respiratory
  bronchioles which branch more to form alveolar
  ducts , the alveolar ducts then lead into minute
  sac-like structure known as the alveoli .

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• Note1
• --- the interchange of gases takes place between
  the air in the alveoli and the blood in the
  capillaries .
• Note2
• --- the blood supply the bronchi and bronchioles
  by right and left bronchial arteries and return
  by the bronchial veins .
• Note3
• ---- the nerve supply the bronchi and
  bronchioles by vagus nerve( parasympathetic )

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• Functions of trachea , bronchi , and bronchioles
  
• 1) because of the presence of the
  cartilages , they remain
  permanently open thus allowing for
  the unobstructed passage of air
  between the out side and the
  alveoli of the lung .

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• 2) the mucus which coats the membrane ensures
  that much of the particulate matter( dust
  and bacteria ) suspended in inspired air is
  removed before it reaches the alveoli
• 3) the wave motion of the cilia of lining
  membrane help in the process of
  expectorant and coughing .
• 4) regulate the volume of entering the
  lungs by the nerve supply
  parasympathetic and sympathetic .

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• (7) the lungs ( page 99 , figure 7-17,18 )
• Position and associated structure
• The lungs are two in number , each one
  lying on each side of the midline in the thoracic
  cavity , they are cone- shaped and having apex ,
  base , costal and a medial surface .

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• apex
• --- round and rises into the root pf the neck .
  associated with it are first rib and the blood
  vessels and nerve in the root of the neck .

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• the base
• --- is concave , associated with the
  thoracic surface of the diaphragm .
• costal surface
• --- is convex , associated with the costal
  cartilages and ribs .

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• medial surface
• --- are concave and separated from each
  other by mediastinum space which is
  occupied by the heart , vessels ,
  trachea , bronchi , oesophagus ,
  lymph node and nerves.

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• Structures entering and leaving each lung are
• ( bronchus , pulmonary artery and vein ,
  bronchial artery , bronchial artery and veins ,
  lymph vessels , nerves )

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• Structure
• Lobes
• The right lung
• is divided into three distinct lobes
• (superior , medial and inferior lobes )
• The left lung
• is divided into two lobe (superior ,
  and inferior lobes )

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• The pleura -
• is consists of a closed sac which contain
  serous fluid ( secreted from epithelial cells to
  prevent flections during breathing ) , formed
  from two layers.
• 1- visceral pleura ---- adherent to
  the lung
• 2 - parietal pleura ----
• is adherent to the inside of
  the chest wall and the thoracic
  surface of the diaphragm.

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• The interior of the lungs
• The lungs are composed of the bronchi ,
  alveoli , connective tissue , blood vessels ,
  lymph vessels and nerves )
• The left lung is divided into two lobes
  and the right lung into three lobes , each lobe
  made up of a large number of lobules

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• The lobules
• Are composed of tiny bronchioles which
  subdivide into terminal bronchioles , respiratory
  bronchioles , alveolar ducts and many thousands
  of alveoli .

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• The pulmonary blood supply
• (page 101 , figure 7-19 , 7-20 )
• pulmonary artery divided into a right
  and left branch then divides into many branches
  and end in capillary network in the wall of the
  alveoli , which conveys deoxygenated blood to
  each lung.

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• The exchange of gases occurs between the
  air in the alveoli and blood in the blood in the
  capillaries , then the capillaries join up into
  two pulmonary veins , which leave the lungs
  convey oxygenated blood to the left atrium of the
  heart .

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• External respiration
• Expansion and contraction of the lunges
  ensure that a regular exchange of gases takes
  place between the alveoli and the external air .

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• The mechanism of respiration is the process
  by which the lungs expand to take in air then
  contract to expel it . its occurs about
• 12 - 18 times per minute respiratory rate( R.R )
  , consist of three phases
• 1- inspiration or inhalation ---- air
  in
• 2 - expiration or exhalation ---- air
  out
• 3 - pause ----- relaxation

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• The main muscles of respiration in normal quiet
  breathing are the intercostals muscles ( 11 pairs
  which occupy the spaces between the 12 pairs of
  ribs ) and the diaphragm ,
• during difficult or deep breathing they are
  assisted by the muscles of the abdomen , neck and
  shoulders .

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• Note1 ---
• the lungs and air passages are never empty
• Note2 ---
• the remaining capacity of the respiratory
  passages is called dead space (D.S ) .
• Note3 ---
• tidal volume (400)ml ( T.V ) is the amount
  of air which passes into and out of the lungs
  during each cycle of breathing.
• Note4 ---
• alveolar ventilation (A.V ) is the amount
  of air which moves into and out of the alveoli
  each minute .

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• ( A.V ) R.R ( T.V - D.S )
• 15 ( 400 - 150)
• 15 250
• 3,750 liter per minute

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• Note ---
• the inter change of gases in the lungs
  occurs between the blood in the capillaries
  network which surrounds the alveoli and
  the air in the alveoli of the lungs .

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• Note --- the inspired air consist of
• Oxygen ( O2 )-------- 21 per cent
• Carbon dioxide (CO2 ) --- ,04 per cent
• Nitrogen(N) and other inert gases
• ---- 79 per cent
• Water vapour ---------- variable .

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• The cycle of respiration
• During the inspiration
• The diaphragm and intercostals muscles
  are contracted , and ribs movement upward
• During the expiration
• The diaphragm and intercostals muscles
  are relaxed , and ribs movement downward

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• Internal or cells respiration
• Note ---
• O2 is carried from the lungs to the
  tissues dissolved in plasma and combination with
  hemoglobin , and the exchange in the tissues
  takes place between the arterial end of the
  capillaries and the tissues fluid from higher
  concentration ( blood ) to a lower
  concentration ( tissue fluid ) .

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• Note ---
• the method of transfer of CO2 from the cells
  into the blood at the end of the capillary is
  also by diffusion . And blood transports CO2 by
  three different mechanisms
• 1) some of CO2 dissolved in the plasma
• 2) some of CO2 combine with sodium as
  sodium bicarbonate
• 3) some of CO2 combine with hemoglobin .

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• Note ---
• the respiration is controlled by nerve
  cells in the brain stem ( resp . center ) in
  medulla oblongata