Respiratory System

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Chapter 9

• Respiratory System

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Points to Ponder

• What are the parts and function of the upper and
  lower respiratory system?
• What is the mechanism for expiration and
  inspiration?
• How is breathing controlled by the nervous system
  and through chemicals?
• Where and how is exchange of gases accomplished?
• What are some common respiratory infections and
  disorders?
• What do you know about tobacco and health?
• What is your opinion about bans and legislation
  on smoking?

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9.1 The respiratory system
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Respiratory Pathway Air Flow
8.1 Overview of digestion

• nose
• pharynx
• larynx
• trachea
• bronchus
• bronchioles
• alveoli

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What constitutes the upper respiratory tract?
9.2 The upper respiratory tract

• Nose
• Pharynx
• Larynx

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The Nose
9.2 The upper respiratory tract

• Opens at the nostrils/nares and leads into the
  nasal cavities
• Hairs and mucus in the nose filters the air
• Mucus ? helps trap dust and move it to the
  pharynx to be swallowed
• The nasal cavity has lot of capillaries that warm
  and moisten the air
• Specialized ciliated cells act as odor receptors
• Nerve impulses generated by the receptors are
  interpreted as smell
• Tear (lacrimal) glands drain into the nasal
  cavities that can lead to a runny nose

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The Pharynx
9.2 The upper respiratory tract

• Funnel-shaped cavity commonly called the throat
• Connects the nasal and oral cavities to the
  larynx
• 3 portions based on location
• Nasopharynx ? where the Nasal cavity opens
• Auditory tubes empty into this location
• Oropharynx ? where the Oral cavity opens
• Laryngopharynx ? opens into the larynx
• Tonsils provide a lymphatic defense during
  breathing at the junction of the oral cavity and
  pharynx
• Contain lymphocytes that protect against invasion
  of foreign antigens that are inhaled
• Respiratory tract assists the immune system in
  maintaining homeostasis

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The Larynx
9.2 The upper respiratory tract

• Triangular, cartilaginous structure that passes
  air between the pharynx and trachea
• Called the voice box and houses vocal cords
• Vocal Cords
• 2 mucosal folds that make up the vocal cords with
  an opening in the middle called the glottis
• Creation of Sound
• Air is expelled through glottis forcing the vocal
  cords to vibrate
• Pitch
• High ? greater the tension, glottis becomes
  narrower
• Lower ? glottis is wider
• Amplitude (volume) degree of vocal cord
  vibrations

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The Larynx

• Creation of Sound
• Air is expelled through glottis forcing the vocal
  cords to vibrate
• Pitch
• High ? greater the tension, glottis becomes
  narrower
• Lower ? glottis is wider
• Amplitude (volume) degree of vocal cord
  vibrations

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Lower Respiratory Tract
9.3 The lower respiratory tract

• Trachea
• Bronchial tree
• Lungs

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The Trachea
9.3 The lower respiratory tract

• A tube, often called the windpipe, that connects
  the larynx with the 1 bronchi
• Made of connective tissue, smooth muscle and
  C-shaped cartilaginous rings
• Lined with cilia and mucus that help to keep the
  lungs clean
• Mucus membrane line trachea
• Pseudostratified ciliated columnar epithelium
• Mucus from goblet cells

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The Trachea

• Coughing
• 1. Tracheal wall contracts, narrowing the
  diameter
• 2. Air moves more rapidly through the trachea
• 3. Expels mucus and foreign objects

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The bronchial tree
9.3 The lower respiratory tract

• Starts with two primary bronchi that lead from
  the trachea into the lungs
• The bronchi continue to branch into secondary
  bronchi until they are small bronchioles about
  1mm in diameter with thinner walls
• Bronchioles eventually lead to elongated sacs
  called alveoli
• Asthma Attach
• smooth muscle of bronchioles contract ? wheezing

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The Lungs
9.3 The lower respiratory tract

• The bronchi, bronchioles and alveoli beyond the
  1 bronchi make up the lungs
• Right lung has 3 lobes --- Left lung has 2
  lobes
• Lobes are divided into lobules
• Each lobule has a bronchiole serving many alveoli
• Each lung is enclosed by membranes called pleura
• Double layer of serous membrane that produces
  serous fluid
• Parietal Pleura adhere to thoracic cavity wall
• Visceral Pleura adhere to surface of lungs
• Surface tension holds the two pleural layers
  together, therefore lungs follow the movement of
  the thorax when breathing
• Surface tension tendency of water molecules to
  cling to one another due to hydrogen bonding
  between molecules

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The Alveoli
9.3 The lower respiratory tract

• 300 million in lungs that increase surface area
• Alveoli are enveloped by blood capillaries
• The alveoli and capillaries are simple squamous
  epithelium to allow exchange of gases
• Oxygen diffuse across alveolar wall to
  bloodstream
• CO2 diffuse from blood across the alveolar wall
  to the aveoli
• Alveoli lined with surfactant that act to keep
  alveoli open
• Decrease surface tension of water

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Two Phases of Breathing/Ventilation
9.4 Mechanism of breathing

• 1. Inspiration an active process of
  inhalation that brings air into the lungs
• 2. Expiration usually a passive process of
  exhalation that expels air from the lungs

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Thoracic Cavity

• Lungs in thoracic cavity
• Rib cage joined to vertebral column and sternum
• Intercostal muscles line between the ribs
• Diaphragm and connective tissue

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Inspiration Active Phase
9.4 Mechanism of breathing

• 1. The diaphragm and external intercostal
  muscles contract
• The diaphragm flattens and the rib cage moves
  upward and outward (active phase)
• 2. Volume of the thoracic cavity and lungs
  increase
• The air pressure within the lungs decrease
• - creating partial vacuum
• Air flows into the lungs
• - Actual flow of air into the alveoli is passive

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Expiration Passive Phase
9.4 Mechanism of breathing

• 1. The diaphragm and external intercostal
  muscles relax
• 2. The diaphragm moves upward and becomes
  dome-shape
• The rib cage moves downward and inward
• 3. Volume of the thoracic cavity and lungs
  decrease
• 4. The air pressure within the lungs increases
• 5. Air flows out of the lungs

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Maximum Inspiratory Effort and Forced Expiration

• Maximum inspiratory effort involves Back, chest,
  and neck
• Increases the size of the thoracic cavity
• Maximize expansion of the lungs
• Maximum Expiration effort
• Contraction of the internal intercostal muscles
• Force rib cage to move downward and inward
• Abdominal wall muscles contract and push against
  the diaphragm
• Increased pressure in the thoracic cavity expels
  air

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Different volumes of air during breathing
9.4 Mechanism of breathing

• Tidal volume
• the small amount of air that usually moves in and
  out with each breath (500 mL)
• Vital capacity
• the maximum volume of air that can be moved in
  plus the maximum amount that can be moved out
  during one breath
• Inspiratory and expiratory reserve volume
• the increased volume of air moving in or out of
  the body (2,900 mL)
• Residual volume
• the air remaining in the lungs after exhalation
• Air is no longer useful for gas exchange

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Visualizing the Vital Capacity
9.4 Mechanism of breathing
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Breathing controlled by the nervous system
9.5 Control of ventilation

• Breathing 12 20 ventilations/min
• Rhythm of ventilation controlled by nervous
  system
• Nervous control (involuntary)
• Inspiration
• Respiratory control center in the brain (medulla
  oblongata) sends out nerve impulses to contract
  muscle for inspiration
• Expiration
• Respiratory control center stops sending neuronal
  signals to the diaphragm and rib cage
• Sudden infant death syndrome (SIDS) is thought to
  occur when this center stops sending out nerve
  signals
• Can voluntarily control breathing to force
  inspiration
• 1. Stretch receptors in alveolar walls initiate
  inhibitory nerve impulses
• 2. Stops respiratory center from sending out
  nerve impulses temporarily

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Breathing is chemically controlled
9.5 Control of ventilation

• Chemical control
• 2 sets of chemoreceptors sense the change in
  chemical composition in body fluids (blood pH)
• 1. Brain (medulla oblongata)
• 2. Circulatory system (carotid bodies and aortic
  bodies)
• Sensitive (stimulated by) carbon dioxide levels
  that change blood pH due to metabolism
• Decrease pH (below 7, increase in H ions)
• Respiratory center increases rate and depth of
  breathing
• More CO2 is removed from blood

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Exchange of gases in the body
9.6 Gas exchanges in the body

• Oxygen and carbon dioxide are exchanged in the
  lungs and tissues
• The exchange of gases is dependent on diffusion
• Partial pressure is the amount of pressure each
  gas exerts (PCO2 or PO2)
• Oxygen and carbon dioxide will diffuse from the
  area of higher to the area of lower partial
  pressure

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External respiration
9.6 Gas exchanges in the body

• Exchange of gases between the lung alveoli and
  the blood capillaries
• PCO2 is higher in the lung capillaries than the
  air thus CO2 diffuses out of the plasma into the
  lungs
• CO2 carried in plasma as bicarbonate ions (HCO3-)
• The partial pressure pattern for O2 is just the
  opposite so O2 diffuses the red blood cells in
  the lungs
• O2 diffuses into plasma and into RBC in lungs
• Carbon dioxide transport carbonic
• H HCO3- H2CO3 anhydrase H2O
  CO2
• Oxygen transport
• Hb O2 HbO2 (oxyhemoglobin)
• (deoxyhemoglobin)

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External respiration

• Hyperventilate (breathe at a high rate)
• Push reaction to the right
• Fewer hydrogen ions ? alkalosis
• High blood pH
• Solution Inhibit breathing
• Hypoventilate (breathe at a low rate)
• Hydrogen ions build up in the blood ? acidosis
• Buffer compensate for low pH
• Solution Increase breathing

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Internal respiration
9.6 Gas exchanges in the body

• The exchange of gases between the blood in the
  capillaries outside of the lungs and the tissue
  fluid
• PO2 is higher in the capillaries than the tissue
  fluid therefore, O2 diffuses out of the blood
  into the tissues
• Oxyhemoglobin gives up oxygen
• HbO2 Hb O2
• Most CO2 is carried as a bicarbonate ion
• carbonic
• CO2 H2O anhydrase H2CO3 H3
  HCO3-

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Internal respiration

• Oxygen diffuses out of the blood into tissues
• - PO2 of tissue fluid is lower than that of
  blood because cells use up oxygen in cellular
  respiration
• CO2 diffuses into the blood from tissues
• PCO2 of tissue fluid is higher than the blood
  because CO2 is produced by cells and collected in
  tissue fluid
• CO2 enters the RBCs and plasma to be either
• Taken up by hemoglobin in RBC to from HbCO2
• Taken up by RBC and formed into HCO3-
• Excess H from this reaction combines with
  Hemoglobin to form HHb, reduced hemoglobin

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Upper respiratory tract infections
9.7 Respiration and health

• Sinusitis blockage of sinuses
• Otitis media infection of the middle ear
• Tubes placed in the eardrums to prevent buildup
  of pressure in the middle ear
• Tonsillitis inflammation of the tonsils
• Laryngitis infection of the larynx that leads
  to loss of voice

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Lower respiratory tract disorders
9.7 Respiration and health

• Pneumonia
• infection of the lungs with thick, fluid build up
• Tuberculosis
• bacterial infection that leads to tubercles
  (capsules)
• Pulmonary fibrosis
• lungs lose elasticity because fibrous connective
  tissue builds up in the lungs usually because of
  inhaled particles
• Emphysema
• chronic, incurable disorder in which alveoli are
  damaged and thus the surface area for gas
  exchange is reduced
• Asthma
• bronchial tree becomes irritated causing
  breathlessness, wheezing and coughing
• Lung cancer
• uncontrolled cell division in the lungs that is
  often caused by smoking and can lead to death

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Health focus Things you should know about
tobacco and health
9.7 Respiration and health

• All forms of tobacco can cause damage
• Smoking increases a persons chance of lung,
  mouth, larynx, esophagus, bladder, kidney,
  pancreas, stomach and cervix
• The 5-year survival rate for people with lung
  cancer is only 13
• Smoking also increases the chance of chronic
  bronchitis emphysema, heart disease, stillbirths
  and harm to an unborn child
• Passive smoke can increase a nonsmokers chance of
  pneumonia, bronchitis and lung cancer