RESPIRATORY SYSTEM

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INTRODUCTION 

Optimal patient care requires that the EMT-I understand the respiratory system.  The following topics will be discussed during this lesson:

 

·                      Airway anatomy

 

·                      Mechanics of Ventilation

 

·                      Physiology of Respiration

 

·                      Regulation of Respiration

 

·                      Assessment of Respiration

 

LESSON OBJECTIVES

At the end of this lesson the participants will be able to

 

1.         Identify the major structures of the upper and lower airways.

 

2.         Identify the muscles of ventilation and describe the mechanics of ventilation.

 

3.         Name the requirements for gas exchanges.

 

4.         Explain how gas is exchanged across the alveolar airways.

 

5.         Discuss the roles of the central and peripheral chemoreceptors.

 

6.         Describe the essential factors of the primary and secondary assessment of the respiratory system.

 

SKILLS

None

 

KEY VOCABULARY 

The following terms will be used during this lesson:

 

·          Aspiration:              accidental inhalation of liquids or solids into the lower airway

 

·          Crackles:                low pitched sounds caused by an accumulation of fluid in the smaller airways

 

·          Diffusion:                the movement of solutes from an area of greater concentration to an area of lower concentration

 

·          Dyspnea:                subjective feeling of shortness of breath or difficulty breathing

 

·          Tidal Volume:         the amount of air moved by a single breath:  normally 500 ml while at rest

 

·          Hyperventilation:     abnormally rapid, deep breathing that results in decreased CO2 levels. symptoms include dizziness, numbness, and carpopedal spasms.

 

·          Hypoventilation:      reduced rate and depth of breathing that results in retention of CO2.

 

·          Hypoxemia:            blood that contains abnormally low oxygen levels

 

·          Ventilation:             mechanical process of moving air into and out of the lungs

 

·          Rales:                     sounds heard when areas of collapsed airways expand with inhalation or when fluid collects in the smaller airways

 

·          Respiration:            the exchange of gases in the alveoli

 

·          Rhonchi:                 sound created by fluid or mucous in the larger airways

 

·          Stridor:                   abnormal “crowing” sound as air moves past an upper airway obstruction

 

·          Tachypnea:             abnormally rapid respiratory rate

 

·          Wheezes:               “whistling” sound created by air movement through constricted bronchioles

 

KEY CONCEPTS

The following section provides information and space for taking notes on the key concepts discussed by the instructor.

 

 

AIRWAY ANATOMY

Upper Airway

·        Location

·          From the nose and mouth to the larynx

 

·        Function

·          Warm, filter, and humidify the air/Sense of smell

·          Protect the lower airways

 

·        Structures

·          Pharynx:           gag reflex that protects the airway

·          Larynx:             contains the vocal cords (“voice box”)

·          Epiglottis:          prevents food and liquids from entering the trachea

 

 

Lower Airway

·        Location

·          From the larynx to the alveoli

 

·        Function

·           Exchange of CO2 and O2

 

·        Structures

·          Trachea:           tube supported by C shaped rings of cartilage

·          Carina:             at the level of the sternal angle where the                                                    trachea splits

·          Bronchi:            left and right mainstem bronchi connect the                                               lungs to the trachea

·          Broncioles:       small airways that are smooth muscles which can                                contract

·          Lungs:              organ of respiration where gas exchange                                                    takes place

·          Alveoli:             main functional units of the respiratory system

·          Pleura:              provides a smooth friction free surface for                                                 the movement of the lungs

 

VENTILATION

Major Muscles of Ventilation

·          Diaphragm

 

 

·          Intercostal

      muscles

 

·          Accessory

      muscles

thin, dome shaped muscle that separates the thoracic and abdominal cavities

 

between the ribs:  allow for chest expansion

 

 

lift the sternum and upper ribs

 

Requirements for Ventilation

·          Patent airway

 

·          Intact nervous system control

 

·          Intact musculature

 

 

 

 

 

 

 

Mechanics of Ventilation

·          Inspiration:              the diaphragm moves downward, the intercostal                                          muscles lift the ribs upward and outward and the                                         accessory muscles lift the sternum and upper ribs.                                        This creates an enlarged thoracic cavity.  Negative                                       pressure draws air in.

 

·          Expiration:              the muscles relax and the chest cavity returns to its                                       normal size.  This creates positive pressure which                                        forces air out.

 

RESPIRATION

Requirements for Gas Exchange

·          Adequate oxygen supply

·          Adequate alveolar perfusion

·          Sufficient hemoglobin

·          Integrity of the alveoli

 

Physiology of Gas Exchange

·          Oxygen diffuses from the alveoli to the capillaries

·          Oxygen combines with hemoglobin

·          Carbon dioxide is released from the hemoglobin

·          Carbon dioxide diffuses from the capillaries to the alveoli

 

Regulation of Respiration

Respiration is controlled by both the voluntary and involuntary nervous system

·        Central Nervous System

·          Respiratory center is in the brainstem

·          Controls the rate and depth of respiration

·        Central Chemoreceptors

·          Located in the brainstem

·          Respond to changes in CO2 levels

·        Peripheral Chemoreceptors

·          Located in the carotids and aorta/Respond to changes in O2 levels

·        Autonomic Nervous System

·          Sympathetic response - dilates bronchioles

·          Parasympathetic response - constricts bronchioles

·        Hypoxic Drive

·          Normally the central and peripheral chemoreceptors function to maintain CO2, O2, and Ph balance.  Patients with chronic lung disorders such as emphysema and bronchitis tend to retain CO2.  Over a period of time the central chemoreceptors become accustomed to the chronically elevated CO2 and fail to respond to changes.  The peripheral chemoreceptors continue to respond to O2 level changes and provide the primary impetus to breath.

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