Respiratory System

• Primary Function

– Gas Exchange

• Secondary Functions

– Speech

– pH regulation of internal environment

• Anatomical Divisions

– Conducting pathways

– Respiratory regions

• sites of gas exchange

• Conducting Pathways

– Upper respiratory tract

• Nasal cavity

• Pharynx

• Nasal Cavity

– Functions

• warms air

• humidifies air

• filters air

– Features of Nasal Cavity

• Conchae

• Ciliated epithelial mucosa

• Nasal cavity communicates with nasal sinuses

• Pharynx

– Functions

• food and air pathways

• resonating chamber for voice

• swallowing

– 3 divisions

• Nasopharynx

• Oropharynx

• Laryngopharynx

• Structural features of pharynx

– Lined with a stratified squamous epithelium

– Skeletal muscle in wall

• Additional structural features

– Eustachian tube opening

– uvula

– tonsils

• Lower Respiratory Tract

– Larynx

– Trachea

– Bronchi

– Bronchioles

• Structure of the Larynx

– Cartilages & ligaments

– Muscles & bone

– Lined with a mucous membrane

Other Features of Larynx

–Vestibular folds (‘false vocal folds’)

– Vocal folds

– Glottis

• Primary Function of the Larynx

– Sound production

• Secondary Functions of the Larynx

– Prevents food & drink from entering lower respiratory tract

• vestibular folds and vocal folds

• epiglottis

• Trachea (‘Windpipe’)

– General features

• 1 inch diameter

• 4-5 inches long

– 1^st inch in neck

– Composed of 15-20 “C” rings

– Rings linked by annular ligaments

• Bronchi (singular: bronchus)

– Primary

• to lungs

– Secondary (lobar)

• to lobes of lungs

– Tertiary (segmental)

• to bronchopulmonary segments of lungs

• Bronchioles

– Branch off of tertiary bronchi

– Less than 1 mm in diameter

– Smooth muscle in walls

• exhibit bronchoconstriction & bronchodilation

• Terminal Bronchioles

– Last bronchioles before alveoli

– Deliver air to lung lobules

Review:

• Anatomical Divisions of Respiratory System

– Conducting pathways

– Respiratory regions: sites of gas exchange

• respiratory bronchioles

• alveoli

• Respiratory Bronchioles

– have alveoli

• Alveoli (singular: alveolus)

–Sites of gas exchange

–Form the respiratory membrane with alveolar capillaries

–Secrete surfactant

• Structure of Lungs

– Alveoli

– Bronchi and Bronchioles

– Reticular CT with lots of elastic fibers

– Blood vessels and nerves

• Pleural Cavities

• Pleural membranes

– Visceral pleura

– Parietal pleura

• Pulmonary Ventilation

– Movement of air into and out of the alveoli

• Ventilation Steps

– Inspiration (quiet or forced)

– Expiration (quiet or forced)

• Muscles of quiet inspiration

– Diaphragm

– External intercostals

• Why does air enter the lungs when these muscles contract?

• Muscles of forced inspiration

• Pect. Minor

• Serratus anterior

• Sternocleidomastoid

• Muscles of quiet expiration

– None!

• Muscles of forced expiration

– Internal intercostals

– Abdominal muscles

–

• Major nerves of respiration

– Phrenic nerves

– Intercostal nerves