The Respiratory System Lesson 1: 29 The Respiratory System Lesson 1:

Lesson Objectives Upon completion of this lesson, students should be able to … Define and spell the terms to learn for this chapter. Explain the purpose and function of the respiratory system. List and explain the structures and functions of the organs of the respiratory system. Explain the different respiratory volumes and capacities.

Critical Thinking Question How might you describe the breathing process to a patient?

The Process of Breathing When we breathe we inhale oxygen and exhale carbon dioxide This exchange of gases gets oxygen to, and carries carbon dioxide away from the cells of the body Respiration is achieved through the mouth, nose, trachea, lungs, and diaphragm Oxygen enters the respiratory system through the mouth and the nose

The Path of Oxygen When Breathing Passes through the larynx Into the trachea Into the alveoli Then diffuses through the capillaries into the arterial blood The waste-rich blood from the veins releases carbon dioxide into the alveoli

The Path of Oxygen When Breathing The diaphragm helps pump air into, and carbon dioxide out of, the lungs Upon exhalation, the carbon dioxide follows the same path out of the lungs by which oxygen flowed into the lungs

The Respiratory System

Upper and Lower Respiratory Tracts The upper respiratory tract consists of: The nose Paranasal sinuses The pharynx (or throat) The lower respiratory tract includes: The larynx (or voicebox) Trachea (which splits into two main branches called bronchi) Tiny branches of the bronchi called bronchioles The lungs

Organs of the Respiratory System Upper Respiratory Lower Respiratory 9

Critical Thinking Question What is the common name for “upper respiratory infection?” 10

Functions of the Nose Cleanses inhaled air Cilia and mucus catch airborne particles Prevents particles from entering airway Moistens inhaled air by producing mucus Warms the inhaled air Turbinate bones, or conchae, create a maze Air circulates through and warms Assists with drainage Sinuses Nasolacrimal duct drains from eyes 11

Critical Thinking Question Why does your nose run when you cry? 12

Internal Structure Septum Conchae Palatine bone of the skull Cartilaginous structure Lined with mucous membrane Divides nose into left and right Conchae Inferior, middle, superior Connect eustachian tube, sinuses, and nasolacrimal duct Palatine bone of the skull Makes up the hard palate Separates the nose from the mouth 13

The Nose 14

The Pharynx Musculomembranous tube about 5 inches long Common path for air and food Branches into trachea (air passageway) and esophagus (food passageway) Contains the tonsils Three parts Nasopharynx Oropharynx Laryngopharynx 15

Critical Thinking Question Based on the names of the parts of the pharynx, where do you think each is located? 16

Note the parts of the pharynx and how they are named. 17

Critical Thinking Question What happens to the pharynx when it gets to this point? 18

The Larynx (The “Voice Box”) Muscular and cartilaginous structure Protected by cartilage Thyroid cartilage Epiglottic cartilage Cricoid cartilage 19

Critical Thinking Question Why would cartilage be a good material for protection? 20

The Larynx (The “Voice Box”) Thyroid cartilage: Largest of the larynx cartilages Commonly known as the “Adam’s apple” Epiglottic cartilage: Also called the epiglottis Closes over the trachea (windpipe) during swallowing to keep food out of the trachea 21

The Larynx (The “Voice Box”) Cricoid cartilage: Allows for large boluses of food to be swallowed Landmark for cricoidotomy when airway is obstructed 22

The Larynx Also known as the “voice box” Contains false and true vocal cords Long and relaxed vocal cords produce low sounds Short, tense vocal cords produce higher-pitched notes Functions in producing vocal sounds 23

The Trachea Cartilaginous tube about 1 inch wide and 4.5 inches long that extends between the larynx and the main bronchi Interior of the trachea is lined with mucous membrane and cilia that trap foreign matter Most important function of the trachea is to serve as an open passageway through which air reaches the lungs Epiglottis is a flap of tissue that covers the trachea when swallowing occurs to prevent food from entering the trachea

Main Branches of the Trachea Extend into the lungs called the bronchi  Are the passageways for air between the trachea and the lungs The right bronchus is the longer, larger branch moving down the right side of the heart The left bronchus is shorter and more vertical, as it makes room for the heart in the chest cavity

Main Branches of the Trachea After entering the lungs at the hilum, the bronchi subdivide into the bronchial tree, which continues to branch into smaller and smaller branches called bronchioles

Bronchi Branches of the trachea – one bronchus to each lung Provide passageway for air into the lungs Bronchi subdivide into progressively smaller branches called bronchioles Bronchioles terminate in air sacs called alveoli 27

Alveoli Small air sacs at the terminal end of bronchioles They are elastic – expand and contract with inhalation and exhalation Surrounded by network of capillaries for gas exchange Capillary network creates the respiratory membrane 28

Structure of the Lungs Contain bronchi, bronchioles, and alveoli 2 lungs separated by the mediastinum Right has 3 lobes; left has 2 lobes Are spongy, porous, and highly elastic Pleural membranes Line the outer surface of the lungs and interior of thoracic cavity Pleural lining produces a lubricant called surfactant 29

Critical Thinking Question Why is the outside lining of the lungs lubricated? 30

Functions of the Lungs The most important function is to bring air into contact with the blood and facilitate the exchange of gases in the alveoli Supply oxygen Remove wastes and toxins Defend against intruders Completes these functions with: 36 types of specialized cells Cilia 31

Critical Thinking Question Why do you think a person’s immunity is affected when cells of the lungs are damaged or destroyed by illness or smoking? 32

External Respiration Actions of External Respiration Processes Ventilation – exchange of air between body and environment Inhalation – taking air and fresh oxygen into the lungs Exhalation – sending air out of the lungs and removing carbon dioxide Processes Air travels through pharynx to trachea and lungs Oxygen delivered to blood in lungs Carbon dioxide removed from blood 33

Muscles that Control Breathing Diaphragm Forms floor of thoracic cavity Separates the abdomen from the thoracic cavity Intercostal muscles Between the ribs External intercostals Internal intercostals 34

Action of the Diaphragm Contracts and moves down Causes a decrease of pressure, or negative thoracic pressure, within the chest cavity Air enters the lungs to equalize the pressure during inhalation 35

Intercostal Muscles External intercostal muscles Assist inhalation Raise the rib cage Enlarge the thoracic cavity Internal intercostal muscles Assist exhalation Reduce the size of the thoracic cavity Force air from lungs 36

Check Your Learning! Do Not Use Your Book! Name the respiratory muscle that is described. Pulls the ribs upward and outward Forms the floor of the thoracic cavity and separates the abdomen from the thoracic cavity Pulls the ribs downward and inward External intercostal Internal intercostal Diaphragm 37

Respiratory Volumes and Capacities Used to measure lung volume and capacity Needed for pulmonary function tests Used in diagnosis of respiratory disorders Used in human performance testing Assesses physical capabilities of healthy individuals 38

Critical Thinking Question When might human performance testing be used? 39

Lung Volumes Tidal Volume (VT) Inspiratory Reserve Volume (IRV) Volume of air entering or leaving the lungs during a single breath Inspiratory Reserve Volume (IRV) Volume of air that can be inspired over and above the resting tidal volume Expiratory Reserve Volume (ERV) Volume of air that can be expired after a normal expiration 40

Lung Volumes Residual Volume (RV) Volume of air remaining in the lungs after a maximal expiration, which can be estimated as 25 percent of the vital capacity 41

Lung Capacities Inspiratory Capacity (IC) Vital Capacity (VC) Maximum volume that can be inspired after a normal expiration = VT + IRV Vital Capacity (VC) Maximum volume that can be expired after a maximal inspiration = VT + IRV + ERV Functional Residual Capacity (FRC) Volume of air left in the lungs after a normal expiration = ERV + RV Total Lung Capacity (TLC) Volume of the lungs when fully inflated = VC + RV (or 1.25 x VC) 42

Other Respiratory Measurements Respiratory Rate (f) Number of breaths per minute Minute Ventilation (VE) Total volume of air expired per minute = VT x f Dead Space (VD) Volume of inspired air that is not available for gas exchange Alveolar Ventilation (VA) Volume of air that reaches the alveoli per minute = (VT – VD) x f 43

Questions? 44