Respiratory System

Functions of the Respiratory System

Functions of the Respiratory System

- main function is breathing, inhalation and exhalation

- gas conditioning

- sound production

- olfaction

- defense

Upper Respiratory Tract

- nose

- paranasal sinuses

- pharynx

Lower Respiratory Tract

- larynx

- trachea

- bronchi and bronchioles

- lungs

External Nose

- framed by frontal, nasal, and maxillary bones

- very thin skin with lots of sebaceous glands

- nasal bones form “bridge” of nose, two pairs of cartilage frame rest of nose

Internal Nose

- nasal cavity divided by the nasal septum

- warms, filters and moistens incoming air

- olfaction and speech modification

Deviated Septum

- caused from blunt trauma or improper growth

- symptoms include: sinus infections, snoring, sneezing, nosebleeds and difficulty breathing

Paranasal Sinuses

- small openings in the frontal, ethmoid, sphenoid and maxillary bones for sinus cavities

- lighten the weight of the head

- humidifies and heats inhaled air

- speech modification

- protection of facial structures

Sinusitis

- caused by infections or allergies

- sinus tissues get inflamed, swollen and red

Pharynx

- connects the nasal cavity/mouth to the larynx/esophagus

- three regions: nasopharynx, oropharynx and laryngopharynx

Nasopharynx

- posterior to the nasal cavity, serving only as an air passageway

- contains the pharyngeal tonsils that can become inflamed and cause difficulty breathing

- pseudostratified columnar epithelium

Oropharynx

- posterior to the oral cavity, food and air pass through it

- stratified squamous epithelium

Laryngopharynx

- passageway for food and air

- stratified squamous epithelium

- directs food into esophagus

- air into trachea pharynx

- food gets preference

Larynx

- voice box with an intricate arrangement of nine cartilages (3 types)

Thyroid Cartilage

- larger in males

- prominence is Adam’s apple

Cricoid Cartilage

- only cartilage to form a complete ring around larynx

Arytenoid Cartilage

- anchor the vocal cords along with two other pairs of cartilage

Sound Protection

- vocal folds consist of vocal ligaments

- covered by mucous membrane

- when air is forced through space between vocal ligaments, vibrations of vocal folds resulting in the production of sound

Laryngitis

- vocal cords run between arytenoid and thyroid cartilages

- inflammation of the larynx

- vocal cords swell an interfere with their ability to vibrate

Trachea

- descends from larynx through neck into mediastinum, ends by dividing into primary bronchi

- contains 16-20 C-shaped rings of hyaline cartilage making it flexible enough to bend, and prevent it from collapsing

- inner membrane consists of ciliated epithelium that keeps the passageway free of dust

Tracheostomy

- when trachea is blocked (foreign object, injury, infection), tracheostomy may be required

- intubation (pushing a tube through pharynx and larynx) another option

Bronchiole Tree

- trachea bifurcates into primary bronchi at the carina, going into each lung

- bronchi enters the lung dividing into secondary bronchi, passing into each lung

- further divides into tertiary bronchi then bronchioles, less cartilage and more smooth muscle

Alveoli

- about 300 million to provide a large space for gas exchange

Type I Alveolar Cells

- simple squamous epithelial cells

- promotes rapid diffusion of gases

Type II Alveolar Cells

- cuboidal in shape

- produce pulmonary surfactant

- prevents collapse of alveoli

Asthma

- muscles around the bronchioles tighten

- lining of the bronchioles swell and get clogged with mucous

Visceral Pleura

- flattened sac surrounding the lungs

Parietal Pleura

- covers the thoracic wall

Pleural Cavity

- space between the visceral and parietal pleura

Pleurisy

- inflammation of the pleura caused by the rubbing together of the membranes leading to pain with breathing

Lungs

- made up of air tubes, space and stroma

Stroma

- framework of connective tissue with many elastic fibers and an extensive network of blood vessels

- pulmonary arteries branch with branches of the bronchial tree and form a network around individual alveoli

Emphysema

- lung disease involving damage to the alveoli

- large air cysts develop where normal lung tissue used to be

- air is trapped in the lungs due to lack of supportive tissue

Bronchitis

- inflammation of the air passages in the lungs

- symptoms include excessive bronchial mucus with a cough producing sputum

- chronic or acute

Chronic Obstructive Pulmonary Disease

- effects are irreversible

- about 80% of patients are smokers

- results in high blood levels of CO2 and low levels of O2

- often tired because accessory muscles required to breathe

Pneumonia

- inflammation of the lung typically caused by an infection

- serious lung condition where the lungs fill with fluid

- can be caused by bacteria, fungus, or a virus

- can be mild, severe, or fatal

Tuberculosis

- bacterial infection that causes more deaths than any other infectious disease

- caused by Myobacterium tuberculosis (bacillus)

- about 2 billion people infected worldwide

- when it becomes active, kills about 60% of people untreated (about 3 million deaths worldwide)

- if treated, about 90% of patients survive

- attacks the lungs but can also affect other body systems

Lung Cancer

- uncontrolled cell growth in lung tissue

- majority of lung cancers are carcinomas, derived from epithelial cells

- non-small cell lung carcinoma are sometimes treated with surgery (more common)

- small cell lung carcinoma responds better to chemotherapy and radiation (less common)

Cystic Fibrosis

- condition in which glands produce excessively sticky mucous that clogs the lungs, liver, pancreas and intestines, making it difficult to breathe and digest food

- hereditary disease caused by a recessive mutation