The RESPIRATORY System

Functions of the Respiratory System

• Primary Function = Gas Exchange

– Bring O2 from the environment to the bloodstream

– To remove CO2 from the body/bloodstream

Respiration

• The exchange of gases between the atmosphere, blood, and cells

• Pulmonary Ventilation - the exchange of air between the atmosphere and lungs

• External Respiration - gas exchange between the lungs & bloodstream

• Internal Respiration - gas exchange between the blood, cells, and tissues

Organs of the Respiratory System

• Nasal Cavity• Pharynx• Larynx• Trachea

• Bronchi• Lungs• Alveoli• Pleura

Respiratory System

Respiratory Structures

Nasal Cavity

• Nares – openings in the nose• Divided into the right and left sides

by the NASAL SEPTUM

Internal Nose Structures

Functions of the Nose

• Warming, moisturizing and filtering incoming air

• Smell (reception of olfactory stimulus)

• Resonating chamber for speech

Pharynx(throat)

• Extends from the internal nares down to the cricoid cartilage of the larynx

• Divided into three areas– Nasopharynx – passageway for air only

• Contains the pharyngeal tonsils (adenoids)

– Oropharynx – passageway for both air & food

• Contains the palatine tonsils– Laryngopharynx – passageway for food

into the esophagus

Regions of the Pharynx

Functions of the Pharynx

• Passageway for food and air• Resonating chamber for speech

Larynx (Voice Box)

• A short passageway connecting the pharynx with the trachea

• Composed of cartilage– epiglottic cartilage (Epiglottis)– thyroid cartilage (Adam’s Apple)– cricoid cartilage

(attaches the Larynx to the Trachea)

Larynx Structures

Epiglottis

• Large leaf-shaped piece of cartilage lying on top of the larynx

• Unattached and acts like a trap door covering the opening to the trachea which is called the glottis

Epiglottis

Glottis

• The opening from the pharynx to the larynx containing the vocal cords– Vocal Cords - mucous membrane folds

extending across the glottis in two layers

• upper layer or folds - false vocal folds• lower layer or folds - true vocal folds

• Sounds originate from vibration of these true vocal cords

Glottis and Vocal Cords

Trachea(windpipe)

• Anterior to the esophagus• Composed of 16 - 20 C-shaped cartilage

rings stacked upon one another– Hyaline cartilage rings

• Divides into right & left bronchi• Carries air to & from the lungs

Trachea and Esophagus

Bronchi

• Tubes that branch off of the trachea at the carina and extend into the lungs

• Serves as a passageway for air• Left Primary Bronchus• Right Primary Bronchus)

– Shorter and more vertical– Swallowed objects more likely to lodge in

the right primary bronchus than the left

Bronchial Tree

Lungs• Paired - cone shaped organs that

occupy most of the thoracic cavity– Right Lung – larger – has three lobes– Left Lung – two lobes– Bronchioles – passageways for air

from the bronchi to the alveoli– Alveoli – air sacs where gas exchange

takes place (diffusion)• Surrounded by a double membrane

called the pleura

Left Lung

Pleural Membrane

• Parietal Pleura - outer layer of the pleural membrane– Lines the thoracic cavity

• Visceral Pleura - inner layer of the pleural membrane– Covers the outer surface of the lungs

• Between the parietal pleura and the visceral pleura is a potential space called the pleural cavity

Alveoli

• Air sacs - where external respiration occurs (gas exchange between the lungs and the blood)

Alveoli

Physiology of Ventilation

• Ventilation - the process of inhaling and exhaling air in and out of the lungs

• Pulmonary Ventilation - the process by which air flows between the lungs and the external environment

Inspiration (Inhalation)

• Bringing air into the lungs from the external environment

Ventilation

Muscles of Ventilation

Expiration (Exhalation)

• Movement of air from the lungs to the external environment

• Normally a passive process (no energy or muscular contractions required)

Physiology of Respiration

RESPIRATORY DISORDERS AND HOMEOSTATIC IMBALANCES

Lung Cancer

• Most fatal cancer in the U.S.• Highly metastatic • Usually linked with cigarette

smoking• Common irritants include smoking,

pollution, dust particles• 20 times more prevalent in

smokers than non- smokers

Emphysema• “Blown up or full of air”• A condition where the alveolar walls

lose their elasticity and remain filled with air during expiration

• Alveoli become damaged and eventually merge together to form large air sacs with reduced overall volume

• Patients often develop a barrel chest• Generally caused by cigarettes,

pollution, industrial dust particles

Coryza and Influenza

• Common cold and flu• Caused by one of many viruses• Antibiotics cannot help• Medications used to treat the

symptoms– sneezing - coughing– congestion - rhinorrhea

• May result in rhinitis

Pneumonia

• Acute infection or inflammation of the alveoli of the lungs

• Most common infectious cause of death in the U.S.

• Alveolar sacs fill with fluid and dead white blood cells reducing the amount of functional surface area of the lungs

• Most commonly caused by bacterium– Streptococcus pneumoniae

• Affects those in poor health or compromised immune system

Tuberculosis (TB)

• Caused by a bacterium– Mycobacterium tuberculosis

• An infectious communicable disease that destroys the lung tissue and pleura

• Replaced by fibrous connective tissue called tubercles

• Disease is spread by inhalation of the bacterium

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