Respiratory System

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Chapter 9

• Respiratory System

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Overview of the respiratory system
9.1 The respiratory system
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What is the pathway that air follows?
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
• The nasal cavity has lots of capillaries that
  warm and moisten the air
• Specialized cells act as odor receptors
• Tear glands drain into the nasal cavities and 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
• Tonsils provide a lymphatic defense during
  breathing at the junction of the oral cavity and
  pharynx

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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

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What constitutes the 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
  cartilaginous rings
• Lined with cilia and mucus that help to keep the
  lungs clean
• Tracheostomya breathing tube may be inserted
  into the trachea when a person is choking due to
  a blocked windpipe.

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The bronchial tree
9.3 The lower respiratory tract

• Starts with two main bronchi that lead from the
  trachea into the lungs
• The bronchi continue to branch until they are
  small bronchioles about 1mm in diameter with
  thinner walls
• Bronchioles eventually lead to elongated sacs
  called alveoli

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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
• The right lung has 3 lobes while the left lung
  has 2 lobes that divide into lobules
• Each lung is enclosed by membranes called pleura

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The alveoli
9.3 The lower respiratory tract

• gt 300 million in the lungs that greatly increase
  surface area
• Alveoli are enveloped by blood capillaries
• The alveoli and capillaries are one layer of
  epithelium to allow exchange of gases
• Alveoli are lined with surfactant that act as a
  film to keep alveoli open
• Respiratory Distress Syndrome affects premature
  infacts born without surfactant

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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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Inspiration
9.4 Mechanism of breathing

• The diaphragm and intercostal muscles contract
• The diaphragm flattens and the rib cage moves
  upward and outward
• Volume of the thoracic cavity and lungs increase
• The air pressure within the lungs decrease
• Air flows into the lungs

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Expiration
9.4 Mechanism of breathing

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

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How is breathing controlled by the nervous system?
9.5 Control of ventilation

• Nervous control
• Respiratory control center in the brain (medulla
  oblongata) sends out nerve impulses to contract
  muscle for inspiration
• Sudden infant death syndrome (SIDS) is thought to
  occur when this center stops sending out nerve
  signals

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Upper respiratory tract infections
9.7 Respiration and health

• Sinusitis blockage of sinuses
• Otitis media infection of 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 usually due to smoking
• 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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TB

• Pulmonary tuberculosisbacterial infection of the
  lungs
• Bacteria invade lungs, and cells form a capsule
  called a tubercle
• The body may destroy the tubercle or the bacteria
  may be released into lung tissue
• PPD Skin test that detects TB in a patient
• http//www.cdc.gov/nchstp/tb/faqs/qa.htm

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Respiratory disorders

• Acute bronchitis
• Infection of primary and secondary bronchi
• Cough becomes deep that expectorates mucus and
  perhaps pus
• Bacterial infection
• May be preceded by viral URI

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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 cervical cancer
• 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