The Respiratory System

Basic functions of the respiratory system

-Supplies body with oxygen

– Removes carbon dioxide

Conducting zone

Respiratory passageways that convey air. Filter, humidify, and warm incoming air

Respiratory zone

-Site of gas exchange in the lungs

– Includes structures that have alveoli

The Nose

• Provides an airway for respiration

• Moistens and warms air

• Filters inhaled air

• Resonating chamber for speech

• Houses olfactory receptors

• Size variation due to differences in nasal cartilages

Nasal conchae

Filter, heat, and moisten incoming air

Nasopharynx

Only air passageway

Uvula(Nasopharynx)

reflects superiorly

Pharyngeal tonsil (adenoids) (Nasopharynx)

Destroys entering pathogens

Oropharynx

Archlike entranceway—fauces, both food and air

– Palatine tonsils and Lingual tonsils

Laryngopharynx

Voice production, provide an open airway, routes air and food into the proper channels

Thyroid cartilage

- forms laryngeal prominence (Adam’s apple)

-3small cartilages; Arytenoid cartilages, Corniculate cartilages, & Cuneiform cartilages

Epiglottis

Tips inferiorly during swallowing

Vocal folds (true vocal cords)

Act in sound production

Glottis

opening between folds and vocal folds together

Pitch

depends on the diameter, length, and tension in the vocal cords

Loudness

depends on the force of air across the vocal folds

Amplification

sound occurs in the sinus cavities

distinct sounds

depends on movement of the lips, tongue, and cheeks

Trachea

Descends into the mediastinum

-C-shaped cartilage rings keep airway open

- Pseudostratified ciliated columnar epithelium lining the lumen

Bronchial Tree

Primary bronchi (main bronchi), Secondary (lobar) bronchi, Tertiary (segmental) bronchi, Bronchioles, Terminal bronchioles

Histamine

induces constriction of bronchioles = asthma attack

Epinephrine

relaxation of smooth muscles = opens airways

Respiratory bronchioles

Gas exchange occurs where smooth muscle is absent

– Branch from terminal bronchiole → alveolar duct→ alveolar sacs

Alveoli

~400 million alveoli account for tremendous surface area for gas exchange

Type I alveolar cells

gas exchange; simple squamous epithelial cells

Type II alveolar cells

Secrete surfactant

– Reduces surface tension within alveoli

Alveolar macrophages

Remove tiniest inhaled particles, migrate into bronchi, ciliary action takes alveolar macrophages to pharynx

Pleura

A double-layered sac surrounding each lung

– Parietal pleura, Visceral pleura

Pleural cavity

Potential space between the visceral and parietal pleurae

Two phases of pulmonary ventilatio

Inspiration—inhalation

Expiration—exhalation

During inspiration:

Volume of thoracic cavity increases

– Decreases pressure

– Diaphragm flattens during contraction

– External intercostal muscles- Contraction raises the ribs

During expiration

the diaphragm and external intercostals relax

Most important respiratory center?

VRG—ventral respiratory group

-Located; in reticular formation in the medulla oblongata

-Neurons generate respiratory rhythm

Chemoreceptors

-Located in aorta and carotid bodies. Sensitive to rising and falling oxygen levels

– CO2 monitored via H+ levels

Bronchial asthma

-Hypersensitivity to irritants or to stress

-Contraction of bronchiole smooth muscle

-Secretion of mucus in airways

Cystic fibrosis (CF)

inherited disease

– Exocrine gland function is disrupted

– Respiratory system affected by viscous mucus that cannot be cleared out by cilia

Chronic obstructive pulmonary disease (COPD)

-Airflow into and out of the lungs is difficult

-Emphysema

-Chronic bronchitis

– History of smoking