Chapter 13
The Respiratory System
BE ABLE TO
•Name the organs of the respiratory passageway.
•Describe the protective mechanisms of the respiratory system.
•Describe the structure and function of the
lungs and the pleural coverings.
The Anatomy of the Respiratory System
• The cardiovascular and
respiratory systems share the responsibility for supplying the body with O2 and disposing of CO2.
• The respiratory organs oversee gas exchange.
• Organs of the respiratory system include the: nose, pharynx, larynx, trachea, bronchi, lungs, and the avleoli.
• Gas exchange takes place only in the alveoli.
The Anatomy of the Respiratory Organs
Nose
• Air enters via the external nares or nostrils.
• Smell receptors line the mucosa of the nasal cavity.
• The mucosa and underlying veins warm and moisten
incoming air.
• Ciliated cells sweep
contaminated mucus to the
throat and then to the digestive system.
• Conchae are three projections of the mucosa that increase surface area for debris capture.
The Anatomy of the Respiratory Organs
Pharynx
• The pharynx or throat is a common passageway for food and air.
• The superior nasopharynx descends from the nasal
cavity to the oropharynx and to the larynopharynx .
• Auditory tubes drain the middle ear into the
nasopharynx.
• Lymphatic tissue called tonsils are found in the pharynx.
• Are the tonsils really necessary?
The Anatomy of the Respiratory Organs
Larynx
• The voice box or larynx routes air and food into the proper
passageways and play a role in speech.
• It is composed of 8 rings of hyaline cartilage and a flap of elastic cartilage called the
epiglottis.
• When eating or drinking the
epiglottis tips over the opening to the larynx to route food to the
esophagus.
The Anatomy of the Respiratory Organs
Trachea
• The trachea or windpipe joins the larynx and travels to the level of the 5th thoracic vertebrae.
• The trachea is lined with a ciliated mucosa that beat opposite to the direction of incoming air.
• The trachea is rigid due to rings of hyaline cartilage.
• Smoking inhibits the action of cilia and ultimately destroy it.
The Anatomy of the Respiratory Organs
Primary Bronchi and the Lungs
• The trachea divides into the left and right primary bronchi.
• The right is wider, shorter, and straighter than the left.
• Smaller subdivisions within the lungs are direct routes to the air sacs.
• The paired lungs occupy the entire thoracic cavity.
• The left has 2 lobes and the right has 3 lobes.
• The pulmonary or visceral pleura cover the surface and the parietal pleura line the thoracic cavity.
• The parietal pleura secretes a lubricating fluid.
The Anatomy of the Respiratory Organs
Primary Bronchi and the Lungs
• The smallest passageways are bronchioles.
• The terminal bronchioles lead into the alveoli or air sacs.
• There are millions of clustered alveoli that make up the bulk of the lungs.
• Alveolar pores connect neighboring air sacs.
• The outer surface of the alveoli are covered with pulmonary capillaries.
• Gas exchange takes place between the blood and the respiratory
membrane of alveoli.
Chapter 13
The Respiratory System
BE ABLE TO
•Explain how the respiratory muscles cause volume changes for air flow.
•Explain the differences between the types of respiratory volumes.
•Describe the process of gas exchange in the lungs and tissues.
•Describe how oxygen and carbon dioxide are transported in the blood.
•Explain what factors control respiratory rate.
•Describe the symptoms of COPD.
•Describe normal changes that occur in the respiratory system from infancy to old age.
Respiratory Physiology
• 4 distinct events occur in respiration:
1) Pulmonary ventilation is breathing.
2) External respiration or gas exchange between pulmonary blood and alveoli.
3) Respiratory gas transport.
4) Internal respiration occurs between blood and tissue cells.
• Breathing involves inspiration and expiration.
• When the diaphragm and
external intercostals contract the size of the thoracic cavity
increases during inspiration.
Respiratory Physiology
• Expiration occurs when the inspiratory muscles relax and the rib cage descends (cavity gets smaller).
• As the volume gets smaller the pressure increases forcing the air out.
• Nonrespiratory air movements are reflex activities such as sneezing or laughing.
• Respiratory volume is determined by many factors, e.g. health, age, physical condition.
• Respiratory volume is the amount of air that is flushed in and out of the lungs and different respiratory volumes can be described:
1) Tidal volume (TV) is normal quiet breathing
2) Inspiratory reserve volume (IRV) is the amount of air that can be forcibly taken in over TV.
3) Expiratory reserve volume (ERV) is the amount of air that can be exhaled after normal expiration.
4) Residual volume is the left over air left in lungs.
• Respiratory capacity is the total amount of exchangeable air in the lungs.
• Spirometers measure changes in air volume inside the apparatus.
• A stethoscope is used to measure bronchial sounds and vesicular breathing sounds.
Gas Transport in the Blood
Control of Respiration
• Although the pons and the medulla control respiratory
rhythm and depth, other factors may influence respiratory rate and depth:
1) Physical factors.
2) Conscious control 3) Emotions
4) Chemical factors
• Eupnea is a normal respiratory rate of 12-15 respirations/minute
• Hypernea is a more vigorous respiratory rate.
• Hyperventilation (common in panic attacks) and
hypoventilation can dramatically change blood pH.
Respiratory Disorders
• Chronic obstructive pulmonary disease (COPD) are a group of diseases that share similar
features:
1) Patients with history of smoking 2) Difficult or labored breathing
3) Coughing and frequent pulmonary infections
4) Most patients are hypoxic
• In emphysema the alveoli enlarge and lungs become less elastic
• In chronic bronchitis a
excessive production of mucus increases lung infection risks.
Developmental Aspects of the Respiratory System
• Premature infants or those with insufficient production of surfactant have infant
respiratory distress syndrome.
• Cystic fibrosis or CF is a genetic
disorder that causes overproduction of mucus that clogs respiratory passages.
• Respiratory rates are highest in infants and drop throughout life.
• Sudden infant death syndrome (SIDS) is linked to neural respiratory control
problems or heart rhythm abnormalities..
• Asthma is a condition of chronic inflamed hypersensitive bronchial passageways.
• As we age lungs lose elasticity and tidal volume drops.
