RESPIRATORY SYSTEM



``RESPIRATORY SYSTEM

A. Introduction

1. Respiratory system consists of the lungs and air passages

2. Responsible for taking in oxygen, a gas needed by all body cells, and removing carbon dioxide, a gas that is a metabolic waste product produced by the cells

3. Body has only a four to six minute supply of oxygen

4. Therefore, respiratory system must work continuously or death will occur

5. Parts of the respiratory system include the nose, pharynx, larynx, trachea, bronchi, alveoli, and lungs

B. Nose

1. Has two nostrils (nares) or openings through which air enters

2. Nasal septum: partition or wall of cartilage divides the nose into two hollow spaces called nasal cavities

3. Nasal cavities

a. Lined with a mucous membrane

b. Have a rich blood supply

c. As air enters the cavities, it is warmed, filtered, and moistened

d. Mucous, produced by the mucous membranes, also helps trap pathogens (germs) and dirt

e. Cilia

(1) Tiny hair- like structures in nasal cavity

(2) Also help trap dirt and pathogens as they enter nose so trapped particles can be pushed toward the esophagus and be swallowed

4. Olfactory receptors for the sense of smell are located in the nose

5. Nasolacrimal ducts drain tears from the eye into the nose to provide additional moisture for the air

C. Sinuses

1. Cavities in the skull around the nasal area

2. Connected to the nasal cavity by short ducts

3. Lined with mucous membrane that warms and moistens air

4. Also provide resonance for the voice

D. Pharynx or throat

1. Lies directly behind the nasal cavities

2. As air leaves the nose it enters the pharynx

3. Three sections

a. Nasopharynx

(1) Upper portion behind the nasal cavities

(2) Pharyngeal tonsils or adenoids (lymphatic tissue) and the auditory (eustachian) tube openings located here

b. Oropharynx

(1) Middle section located behind the oral cavity

(2) Receives both air from the nasopharynx and food and air from the mouth

c. Laryngopharynx

(1) Bottom section of the pharynx

(2) Branches into the trachea, which carries air to and from the lungs, and the esophagus, the tube that carries food to the stomach

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E. Larynx

1. Voice box

2. Lies between the pharynx and trachea

3. Has a framework of cartilage commonly called the Adam’s apple

4. Contains two folds called vocal cords

a. Opening between the vocal cords is called the glottis

b. As air leaves the lungs, the vocal cords vibrate and produce sound

c. Tongue and lips act on the sound to produce speech

d. Epiglottis

(1) Special piece of cartilage

(2) Leaf like structure that closes the opening into the larynx during swallowing

(3) Prevents food and liquids from entering the respiratory tract

F. Trachea or windpipe

1. Tube extending from the larynx to the center of the chest

2. Carries air between the pharynx and bronchi

3. Series of C-shaped cartilage, which are open on the dorsal or back surface, help keep the trachea open

G. Bronchi

1. Two divisions of the trachea near the center of the chest

a. Right bronchus and left bronchus

b. Right bronchus is shorter, wider, and extends more vertically than the left bronchus

2. Each bronchus enters a lung and carries air from the trachea to the lungs

3. In the lungs, the bronchi continue to divide into smaller and smaller bronchi

4. Smaller branches are called bronchioles

5. Smallest bronchioles, called terminal bronchioles, end in air sacs called alveoli

H. Alveoli

1. Air sacs that resemble a bunch of grapes

2. Adult lung contains approximately 500 million alveoli

3. Made of one layer of squamous epithelium tissue

4. Contain a rich network of blood capillaries

5. Capillaries allow oxygen and carbon dioxide to be exchanged between the blood and the lungs

6. Inner surface of alveoli are covered with surfactant

a. Lipid or fatty substance

b. Helps prevent alveoli from collapsing

I. Lungs

1. Organs that contain divisions of the bronchi and alveoli

2. Right lung has three sections or lobes: superior, middle, and inferior

3. Left lung has only two lobes, the superior and inferior

4. Left lung is smaller because the heart lies more to the left side of the chest

5. Pleura: membrane or sac enclosing each lung

a. Consists of two layers

(1) Visceral pleura attached to surface of lung

(2) Parietal pleura attached to chest wall

b. Pleural space

(1) Located between the two layers

(2) Filled with a thin layer of pleural fluid that lubricates the membranes and prevents friction as the lungs expand during breathing

6. Both of the lungs, along with the heart and major blood vessels, are located in the thoracic cavity

I. Ventilation: process of breathing

1. Two phases: inspiration and expiration

2. Inspiration or inhalation

a. Process of breathing in air

b. Diaphragm (dome-shaped muscle between the thoracic and abdominal cavity) and the intercostal muscles (between the ribs) contract and enlarge the thoracic cavity

c. This creates a vacuum

d. Air rushes in through the air tubes to the alveoli, where the exchange of gases takes place

3. Expiration or exhalation

a. Process where air leaves the lungs

b. Diaphragm and intercostal muscles relax

c. Air is forced out of the lungs and air passages

4. Process of respiration is controlled by the respiratory center in the medulla oblongata of the brain

a. Decreased amount of oxygen as seen in certain diseases (asthma, congestive heart failure, or emphysema) or increased amount of carbon dioxide in the blood causes the center to increase the rate of respirations

b. Process is usually involuntary, but a person can control the rate of breathing by breathing faster or slower

J. Two main stages of respiration

1. External respiration and internal respiration

a. External respiration

1). Exchange of oxygen and carbon dioxide between the lungs and bloodstream

2). Oxygen, breathed in through the respiratory system, enters the alveoli

(a) Concentration of oxygen in the alveoli is higher than the concentration in the blood capillaries

(b) Oxygen leaves the alveoli and enters the capillaries or bloodstream

(c). Carbon dioxide, a metabolic waste product, is carried in the bloodstream

(1) Concentration of carbon dioxide is higher in the capillaries

(d) It leaves the capillaries and enters the alveoli

(e) Alveoli expel it from the body during exhalation

b. Internal respiration

1). Exchange of carbon dioxide and oxygen between the tissue cells and bloodstream

2). Oxygen is carried to the tissue cells by the blood

(a) Concentration of oxygen is higher in the blood than in the tissue cells

3) Oxygen leaves the blood capillaries and enters tissue cells

4) Tissue cells then use the oxygen and nutrients to produce energy, water, and carbon dioxide, a process called cellular respiration

(a) Level of carbon dioxide is higher in cells

5) Carbon dioxide leaves the cells and enters the bloodstream to be transported back to the lungs where external respiration takes place

K. Diseases and abnormal conditions

1. Asthma

a. Respiratory disorder usually caused by sensitivity to an allergen such as dust, pollen, animals, or foods

b. Stress, overexertion, and infections can also cause an asthma attack

c. Symptoms

(1) Occur when bronchospasms narrow openings of bronchioles, mucus production increases, and edema develops in the mucosal lining

(2) Dyspnea and wheezing

(3) Coughing with expectoration of sputum

(4) Tightness in the chest

d. Treatment

(1) Bronchodilators to enlarge the bronchioles

(2) Epinephrine and anti-inflammatory medications

(3) Oxygen therapy

e. Identification and elimination of or desensitization to allergens causing the problem is important in preventing asthma attacks

2. Bronchitis

a. Inflammation of the bronchi and bronchial tubes

b. Acute bronchitis

(1) Usually caused by an infection

(2) Characterized by a productive cough, dyspnea, chest pain, and fever

(3) Treated with antibiotics, expectorants to remove excessive mucus, rest, and drinking large amounts of water

c. Chronic bronchitis

(1) Occurs after frequent attacks of acute bronchitis and long-term exposure to pollutants or smoking

(2) Characterized by chronic inflammation, damaged cilia, and enlarged mucous glands

(3) Symptoms

a) Excessive mucus resulting in a productive cough

b) Wheezing and dyspnea

c) Chest pain

d) Prolonged expiration of air

(4) Treatment but no cure

a) Antibiotics and bronchodilators

b) Respiratory therapy

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3. Chronic obstructive pulmonary disease (COPD)

a. Any chronic lung disease that results in obstruction of the airways

b. Disorders such as chronic asthma, chronic bronchitis, emphysema, and tuberculosis lead to COPD

c. Smoking is the primary cause, but allergies and chronic respiratory infections are also factors

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4. Emphysema

a. Noninfectious chronic respiratory condition

b. Occurs when the walls of the alveoli deteriorate and lose their elasticity

(1) Carbon dioxide remains trapped in the alveoli

(2) Poor exchange of gases

c. Most common causes are heavy smoking and prolonged exposure to air pollutants

d. Symptoms

(1) Dyspnea and a feeling of suffocation

(2) Pain and a barrel chest

(3) Chronic cough

(4) Cyanosis

(5) Rapid respirations with prolonged expiration

(6) Eventual respiratory failure and death

e. Treatment but no cure

(1) Avoiding smoking

(2) Bronchodilators

(3) Prompt treatment of respiratory infections

(4) Oxygen therapy and respiratory therapy

5. Epistaxis or nosebleed

a. Occurs when capillaries in nose become congested and bleed

b. Causes

(1) Injury

(2) Blow to the nose

(3) Hypertension

(4) Chronic infections

(5) Anticoagulant drugs

(6) Blood diseases such as hemophilia or leukemia

c. Treatment

(1) Compress the nostrils toward the septum, elevate the head and tilt it slightly forward, and apply cold compresses

(2) At times it is necessary to insert nasal packs or cauterize (burn and destroy) the bleeding vessels

(3) Eliminate an underlying cause such as hypertension

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6. Influenza or flu

a. Highly contagious viral infection of the upper respiratory system with a sudden onset

b. Symptoms

(1) Chills and fever

(2) Cough, sore throat, and runny nose

(3) Muscle pain and fatigue

c. Treatment

(1) Bed rest and fluids

(2) Analgesics for the pain and antipyretics for fever

(3) Antibiotics not effective against viruses, but they are given at times to avoid secondary infections such as pneumonia

d. Immunization with a flu vaccine

(1) Recommended for the elderly, individuals with chronic diseases, pregnant women, and health care workers

(2) Many different viruses cause influenza, so vaccines are developed each year to immunize against the most common viruses identified

7. Laryngitis

a. Inflammation of the larynx and vocal cords

b. Frequently occurs with other respiratory infections

c. Symptoms

(1) Hoarseness or loss of voice

(2) Sore throat

(3) Dysphagia or difficulty in swallowing

d. Treatment

(1) Rest and fluids

(2) Limited use of the voice

(3) Medications if an infection is present

8. Lung cancer

a. Leading cause of cancer death in both men and women

b. It is a preventable disease, because the main cause is exposure to carcinogens in tobacco, either through smoking or through exposure to “second hand” smoke

c. Three common types of lung cancer

(1) Small cell

(2) Squamous cell

(3) Adenocarcinoma

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SPECIMEN 1: Lung With Cancer - The cancer is the grayish-white bumps on and in the lung. Every time you smoke a cigarette, you increase your risk of death from this kind of cancer.

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SPECIMEN 2: Lung Cancer - This finger-shaped growth partly blocking the windpipe is lung cancer.

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SPECIMEN 3: Bone with Cancer - This is a backbone with spots of cancer. Bone cancer is very painful, and hard to cure.

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SPECIMEN 4: Liver with Cancer - The liver filters blood. Cancer in the lungs can spread to the liver. The cancer is seen here as white spots. This cancer is very painful.

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SPECIMEN 5: Heart with Cancer - The white, wormy-looking bumps on this heart are cancer. Lung cancer caused by smoking can spread to the heart.

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SPECIMEN 6: Brain with Cancer - This is a brain with cancer. Notice the large area on the right side that has been destroyed. Is your smoking habit worth cancer like this?

d. Symptoms

(1) None in the early stages

(2) Chronic cough

(3) Hemoptysis: coughing up blood- tinged sputum

(4) Dyspnea and chest pain

(5) Fatigue and weight loss

e. Prognosis is poor since the disease is usually advanced before it is diagnosed

f. Treatment: surgical removal of the cancerous sections of the lung, radiation, and/or chemotherapy

9. Pleurisy

a. Inflammation of pleura or membranes of the lungs

b. Usually occurs with pneumonia or other infections

c. Symptoms

(1) Sharp stabbing pain while breathing

(2) Crepitation or grating sounds in the lungs

(3) Dyspnea and fever

d. Treatment

(1) Rest

(2) Medications to relieve the pain and inflammation

(3) If fluid collects in the pleural space, a thoracentesis (withdrawal of fluid through a needle) is done to remove fluid and prevent compression of the lungs

10. Pneumonia

a. Inflammation or infection of the lungs with a buildup of fluid or exudate in the alveoli

b. Usually caused by a bacteria, virus, or chemicals

• bacterial pneumonia - caused by various bacteria. The streptococcus pneumoniae is the most common bacterium that causes bacterial pneumonia.

Many other bacteria may cause bacterial pneumonia including:

o Group B streptococcus (most common in newborns)

o Staphylococcus aureus

o Group A streptococcus (most common in children over age 5)

Bacterial pneumonia may have a quick onset and the following symptoms may occur:

o productive cough

o pain in the chest

o vomiting or diarrhea

o decrease in appetite

o fatigue

• viral pneumonia - caused by various viruses, including the following:

o respiratory syncytial virus, or RSV (most commonly seen in children under age 5)

o parainfluenza virus

o influenza virus

o adenovirus

Early symptoms of viral pneumonia are the same as those of bacterial pneumonia. However, with viral pneumonia, the respiratory involvement happens slowly. Wheezing may occur and the cough may worsen.

Viral pneumonias may make a child susceptible to bacterial pneumonia.

• mycoplasma pneumonia - presents somewhat different symptoms and physical signs than other types of pneumonia. It is caused by mycoplasmas, the smallest free-living agents of human disease, which have the characteristics of both bacteria or viruses, but which are not classified as either. They generally cause a mild, widespread pneumonia that affects all age groups.

Symptoms usually do not start with a cold, and may include the following:

o fever and cough are the first to develop

o cough that is persistent and may last three to four weeks

o a severe cough that may produce some mucus

Other less common pneumonias may be caused by the inhaling of food, liquid, gases or dust, or by fungi.

c. Symptoms: chills, fever, chest pain, productive cough, dyspnea, and fatigue

d. Treatment: bedrest, fluids, antibiotics if indicated, respiratory therapy, and pain medication

11. Rhinitis

a. Inflammation of nasal mucous membrane resulting in a runny nose, soreness, and congestion

b. Common causes are infections and allergens

c. Treatment: fluids and medications to relieve congestion

12. Sinusitis

a. Inflammation of mucous membrane lining the sinuses

b. Usually caused by a bacteria or virus

c. Symptoms

(1) Headache or pressure

(2) Thick nasal discharge and congestion

(3) Loss of resonance in the voice

d. Treatment

(1) Antibiotics if indicated

(2) Analgesics for pain

(3) Decongestants to loosen secretions

(4) Moist inhalations

(5) Surgery in chronic sinusitis to open the cavities and encourage drainage

13. Tuberculosis (TB)

a. Infectious disease of the lungs caused by the bacterium Mycobacterium tuberculosis

b. At times, white blood cells surround invading TB organisms

(1) Wall them off, creating a nodule called a tubercle

(2) Organisms remain dormant in the tubercle

(3) Can cause an active case of tuberculosis later if body resistance is lowered

c. Symptoms of an active case of TB

(1) Fatigue and chest pain

(2) Fever and night sweats

(3) Weight loss

(4) Hemoptysis or coughing up blood- tinged sputum

d. Treatment

(1) Administration of drugs for one or more years to destroy the bacteria

(2) Good nutrition and rest

e. In recent years, a new strain of the TB bacterium that is resistant to drug therapy has created a concern that tuberculosis will become a widespread infectious disease

14. Upper respiratory infection (URI) or common cold

a. Inflammation of mucous membrane lining upper respiratory tract

b. Caused by viruses and highly contagious

c. Symptoms: fever, runny nose, watery eyes, congestion, sore throat, and hacking cough

d. No cure and minimal treatment

(1) Symptoms usually last about a week

(2) Analgesics for pain and antipyretics for fever

(3) Rest and increased fluid intake

(4) Antihistamines to relieve congestion

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