The Respiratory System

System Overview Includes tubes that remove particles from incoming air and transport air in and out of the lungs Microscopic air sacs for gas exchange Organs include: –Nose, nasal cavity, and paranasal sinuses –Pharynx –Larynx –Trachea –Bronchial tree –Lungs

Steps of Respiration Respiration = the process of gas exchange between the atmosphere and body cells 1.Ventilation 2.Gas exchange between blood and air in lungs 3.Gas transport between lungs and body cells 4.Gas exchange between blood and body cells

Upper and Lower Respiratory Tracts Upper Respiratory Tract –Organs located outside the thorax Lower Respiratory Tract –Organs located within the thorax

The Nose Supported by bone and cartilage Nostrils Nasal cavity Nasal septum Nasal conchae –Support mucous membranes –Pseudostratified columnar epithelium and goblet cells –Extensive network of blood vessels to warm air

Paranasal Sinuses Air-filled spaces within: –Maxillary bones –Frontal bone –Ethmoid bone –Sphenoid bone Reduce skull weight Resonance chambers

Pharynx Behind the oral cavity and between the nasal cavity and the larynx Passageway for food and air Helps produce speech

Larynx Enlargement at the top of the trachea and below the pharynx Conducts air in and out of the trachea Prevents foreign objects from entering trachea Houses vocal cords Epiglottis

Vocal Cords Horizontal folds of muscle and CT with a mucous membrane covering False vocal cords True vocal cords Speech is formed by changing the shape of the pharynx and oral cavity –Words formed by the tongue and lips –Loudness –Pitch Glottis

Trachea AKA windpipe Extends in front of the esophagus and into the thoracic cavity Splits into left and right bronchi Ciliated epithelium and goblet cells –Filters incoming air –Sweeps particles out into pharynx 20 hyaline cartilage rings Soft tissue on posterior  esophagus can expand as food is swallowed

Bronchial Tree Branched airways leading from trachea to lungs Structurally similar to trachea with less cartilage Mucous membranes filter incoming air and distribute air to alveoli

Passage of Air Though the Bronchial Tree Primary bronchi  secondary bronchi  bronchioles  alveolar ducts  alveoli

Lungs Soft, spongy, cone-shaped organs in thoracic cavity Lungs separated by the heart Enclosed by thoracic cage and diaphragm Suspended from bronchi and some large blood vessels Right lung (3 lobes) is larger than left (2 lobes) Visceral pleura

Alveoli Microscopic air sacs Clustered at distal ends of alveolar ducts Consist of tiny spaces within simple squamous epithelium walls Dense capillary network Large surface area for gas exchange Surfactant

Breathing Breathing consists of 2 processes: 1.Inspiration (inhalation) 2.Expiration (exhalation) Air moves into the lungs because of atmospheric pressure. When lung pressure is lower than atmospheric pressure because of diaphragm and intercostal muscle contractions  inspiration When muscles relax and lungs and thoracic cage return to normal size  expiration

Control of Breathing Controlled by the respiratory center of the medulla oblongata and the pons May also be affected by –Chemicals in body fluids (CO2, H+, O2) –Degree to which lung tissue stretches –Emotional state –Hyperventilation