Respiratory System

Two Respiratory Tracts

Upper Respiratory Tract• Nose• Nasal cavity• Paranasal sinuses• Pharynx• Epiglottis

Lower Respiratory Tract• Larynx• Trachea• Bronchial tree• lungs

I. Upper Respiratory Tract

A. Nose• Supported by bones

and cartilage• Hairs guard nostrils

that prevent entry of large particles

I. Upper Respiratory Tract

B. Nasal Cavity• Hollow space behind the nose• Nasal septum: bone and cartilage that divides

nose into left and right sides• Nasal conchae: bones that divide nasal cavity

into passageways and support mucus membranes• (superior, middle, inferior passageways)

I. Upper Respiratory Tract

I. Upper Respiratory TractB. Nasal Cavity

• Sticky mucus traps dust and other particles/filters air

• Particles in mucus are swallowed and destroyed by gastric juice in stomach

• ** deviated septum: can obstruct the nasal cavity

• ** Anthrax is a really small bacteria that bypasses the hair/mucus so it is inhaled

I. Upper Respiratory Tract

C. Paranasal sinuses• Air-filled spaces within bones of the face and

opening into nasal cavity• frontal sinus (above nose) & sphenoidal sinus

(beside nose)• Function: reduce weight of skull, affect voice• Sinus headache: blocked drainage

I. Upper Respiratory Tract

D. Pharynx (AKA the throat!)• Passageway for food to travel to esophagus and

for air to pass between nose and larynx

E. Epiglottis• Flap that separates the trachea from the

esophagus while swallowing

II. Lower Respiratory Tract

A. Larynx• Airway at the top of the trachea and below the

pharynx• Conducts air in/out of trachea, prevents foreign

objects from entering trachea, houses vocal cords

• Made of muscle and cartilages• Largest = thyroid = “Adam’s apple”

• Vocal cords: folds in larynx that vibrate when air passes between them

• Laryngitis: hoarseness/lack of voice: mucous membrane of larynx is swollen, prevents vocal cords from vibrating freely

II. Lower Respiratory Tract

B. Trachea• Windpipe• Flexible cylindrical tube anterior to esophagus

that runs anterior to thoracic cavity• Splits into left and right bronchi• Ciliated mucous membrane lines inner wall

filters air, moves trapped particles upwards• Bands of hyaline cartilage prevent trachea

from collapsing/blocking airway

Lungs

• Spongy, air-filled organs located on either side of the thoracic cavity (chest)

• Gas exchange occurs in alveoli (O2/CO2)– Upper Lobe– Middle Lobe– Lower Lobe

Pleural Cavity

• Pleura – serous membrane that folds back on itself to form a double layer– Outer layer attaches to chest wall– Inner layer attaches to superior surface of lungs– Resulting “cavity” contains pleural fluid.

Diaphragm

• Skeletal muscle sheet that extends across the bottom of the rib cage

• Separates thoracic cavity from abdominal cavity

• Contracts during inhalation to enlarge the thoracic cavity