The Respiratory System

Involves the exchange of

gases between cells, blood and the atmosphere

Types of Respiration Pulmonary ventilation

inspiration expiration

External respiration occurs in the lungs

Internal respiration occurs in the tissues

Organs of Respiration

Nose, Pharynx,Larynx,Trachea,

Bronchial Tree, Lungs

NOSE Moistens, warms,

and filters air Houses olfactory

receptors Serves as

resonating chamber for speech

Nasal septum divides nasal cavity

PALATE Serves to separate the nasal

cavity from the oral cavity Hard palate Soft palate Uvula

PHARYNX Nasopharynx - upper portion,

region above the soft palate Oropharynx - middle portion, area

behind the oral cavity Laryngopharynx - lower portion,

area below the epiglottis

LARYNX Functions to prevent food or fluid

from entering the respiratory system during swallowing and allows air flow during breathing

Production of sound is secondary function

Larynx Unpaired cartilages - thyroid,

cricoid, epiglottis Paired cartilage - arytenoid,

corniculate, cuneiform Vocal folds Glottis

TRACHEA Tubelike structure leading from

the larynx to bronchial tree Consists of smooth muscle and

“C” shaped hyaline cartilage rings Lined with psuedostratified ciliated

columnar epithelium Mucociliary escalator

BRONCHIAL TREE Includes a right and left primary

bronchus which divides to produce secondary bronchi, tertiary bronchi and bronchioles

Terminal bronchioles branch into respiratory bronchioles which divide into alveolar ducts that connect to alveoli

ALVEOLI Functional unit of the lungs where

gas exchange occurs (300 million) Thin walls made of simple

squamous epithelium Type I and type II alveolar cells Diffusion of gases takes place

across an alveolar-capillary respiratory membrane

LUNGS Paired organs in the thoracic cavity Right lung : 3 lobes

horizontal/oblique fissure Left lung : 2 lobes

oblique fissure Apex/Base Hilus

PLEURAL MEMBRANES Parietal pleura Visceral pleura Pleural cavity Pleurisy Pneumothorax

Physiology of Respiration

Pressures Atmospheric pressure - 760mm Hg Intrapleural pressure - is always less

than atmospheric and alveolar pressure

Alveolar (intrapulmonary) pressure - changes with phases of breathing

Pressure changes in lungs are produced by variations in lung volume

BOYLE’S LAW The pressure of a gas is inversely

proportional to its volume More volume-less pressure Less volume - more pressure

Inspiration Expiration

Alveolar pressure is below atmospheric pressure due to increased volume

Air flows into lungs 760 vs 758 mm Hg

Alveolar pressure is above atmospheric pressure due to decreased volume

Air flows out of lung

762 vs 760 mm Hg

Respiratory Air Volumes Tidal volume Inspiratory reserve volume Expiratory reserve volume Vital capacity Residual volume Spirometer

Regulation of Respiration Medullary rhythmicity center -

medulla oblongata controls basic rhythm of respiration

Control centers in the pons pneumotaxic center inhibits

inspiration apneustic area stimulates inspiration

Gas Transport

Oxygen Transport 98% of oxygen is bound to

hemoglobin as oxyhemoglobin Each hemoglobin molecule has the

capacity to bind with four oxygen molecules

Hypoxia

Factors Affecting Hemoglobin Saturation Partial pressure of oxygen

increase pO2, the greater the % saturation

pH - in an acid environment, O2 splits more readily from hemoglobin

Temperature - the higher the temperature, the more oxygen released from hemoglobin

Carbon dioxide tranport 70% of CO2 is transported in the

plasma as bicarbonate ion 23% of CO2 is bound to the globin

part of hemoglobin as carbominohemoglobin

7% is dissolved in the plasma

RESPIRATORY DISORDERS COPD (Chronic

Obstructive Pulmonary Disease)

Asthma Bronchitis Emphysema Lung Cancer Tuberculosis

Cystic Fibrosis Cheyne-Stokes

Respiration Pneumonia Sleep Apnea SIDS