Respiratory System

Respiratory System

• Upper Respiratory System– Nose– Nasal cavity– Pharynx

• Lower Respiratory System– Larynx– Trachea– Bronchi– Lungs

Respiratory Tract

• Conducting portion– Nasal cavity to smallest bronchioles of lung– Getting air to the exchange zone

• Respiratory portion– Alveoli– Gas exchange

Phases of Respiration

• 1. Pulmonary ventilation– Moving air in and out of lungs

• 2. External respiration– Gas exchange between blood and air (alveoli)– O2 in, CO2 out

• 3. Transport of respiratory gases– Blood, RBC

• 4. Internal respiration– Gas exchange between blood and cells– O2 into cells, removal of CO2

Nose

• Visible part of respiratory system

• Airway for respiration• Moistens and warms air• Filters air• Resonating chamber for

speech• Smell receptors• PSCC epithelium• Conchae bones

Pharynx (Throat)

• Food and air passage way

• Three divisions – NASOPHARYNX: air only. Back of nasal

cavity. PSCC epithelium– OROPHARYNX: food and air. Back of mouth.

Stratified squamous epithelium.– LARYNGOPHARYNX: air and food. Distal

region of the pharynx. Extends to the larynx. Stratified squamous epithelium

Larynx

• From the pharynx air passes through an opening called the GLOTTIS

• The larynx protects the glottis• The larynx is composed of several cartilages

– Thyroid cartilage (Hyaline) – laryngeal prominence– Cricoid cartilage (Hyaline)– Epiglottis (Elastic)– Arytenoid cartilage (Hyaline)– Corniculate cartilage (Hyaline)– Cuneiform cartilage (Hyaline)

Sound Production

• Larynx is also called the voice box• Vestibular ligaments and vocal ligaments are

found in the larynx• Anchored between the thyroid and arytenoid

cartilages• The vocal ligaments are very elastic and vibrate

to produce sound – TRUE VOCAL CORDS• Vestibular ligaments do not produce sound –

FALSE VOCAL CORDS

Trachea

• Windpipe• Passage for air to the lungs• About 1 inch in diameter, and 4.25 inches long• Consists of 15-20 tracheal cartilages• Tracheal cartilages are hyaline cartilage and are

“C” shaped• Respiratory epithelium is PSCC• Trachea ends at the CARINA• Divides into the right and left primary bronchi

Trachea

Lungs

• Lungs occupy the pleural cavities

• Lungs have a tip called the APEX and a flatter BASE

• Right lung has 3 lobes, left lung has 2 lobes

• Surface of the lungs is covered by the visceral pleura

Bronchial Tree

• Primary bronchus

• Secondary bronchus – one for each lobe

• Tertiary bronchus

• Terminal bronchioles

• Respiratory bronchioles

• Alveolar ducts

• Alveolar sacs – gas exchange

Lung Lobule

Changes in the bronchial tree

• As the bronchial passageways get smaller the cartilage rings are replaced by cartilage plates

• Terminal bronchioles lack cartilage, mostly smooth muscle

• Epithelium changes as well:– PSCC in the primary, secondary, tertiary bronchi– Ciliated simple columnar in the larger bronchioles– Ciliated simple cuboidal in the smaller bronchioles– Simple cuboidal in the terminal bronchioles

Respiratory Membrane

• Alveolar endothelium = simple squamous

• Pulmonary endothelium = simple squamous

• These endothelial membranes fuse to form the respiratory membrane

• Gases diffuse across this tiny space: oxygen in, carbon dioxide out

Lung histology

Respiratory Membrane

Respiratory Muscles

• Diaphragm– Increases the volume of thoracic cavity to

draw air into lungs

• External intercostals– Assist in inspiration by elevating ribs

• Internal intercostals– Depress the ribs, reduce the width of the

thoracic cavity and assist in expiration