The Respiratory System Structures Thoracic Cavity chest cavity

The Respiratory System

Structures ¡ ¡ Thoracic Cavity- chest cavity contains all respiratory organs Pleural Membranemembrane surrounding each lung

Mechanism of Breathing

1. INHALATION Ribs are raised (rib muscles contract) ¡ Diaphragm lowers ¡ Pressure in thoracic cavity drops = INHALE ¡

2. EXHALATION Ribs lowered (rib muscles relax) ¡ Diaphragm is raised ¡ Pressure in thoracic cavity increases = EXHALE ¡

Gas Exchange at Alveoli ¡ ¡ Pulmonary arteries (from heart) bring blood LOW in O 2 to alveoli of lungs Pulmonary veins (from lungs) return blood that is HIGH in O 2 to heart

Movement of Gases inside Alveoli

Pathway of Air STRUCTURE FUNCTION OR APPEARANCE 2 Nasal passages - filtering (hairs/cilia) - warming - moistening Nose Nasopharynx - olfactory cells (odour receptors) - tear ducts drain into nasal cavities - joining of nasal cavities

Pathway of Air (cont) STRUCTURE FUNCTION OR APPEARANCE Pharynx Larynx - glottis (opening) - epiglottis (flap over trachea) - vocal cords Trachea - cartilage; stiff tube - cilia beat dust/particles upwards

Pathway of Air (cont) STRUCTURE FUNCTION OR APPEARANCE Bronchus - branch to left & right lungs - right lung = 3 lobes - left lung = 2 lobes Bronchioles - smallest branches - no cartilage Alveoli - air sacs *gas exchange - blood capillary network - lipoprotein coating so won’t stick shut

VENTILATION Maintains a maximum O 2 concentration & a minimal CO 2 concentration within alveoli ¡ Mammals ventilate by negative pressure breathing 1. rib muscles contract: expands rib cage expands lungs 2. diaphragm contracts & flattens: pulls air in ¡

Diaphragm movement ¡ Shape of diaphragm moves from curved upwards to flat (pushed down)

Process of Breathing 1. Inspiration & Expiration 2. External Respiration: exchanging O 2 & CO 2 between air & blood 3. Internal Respiration: exchanging O 2 & CO 2 between blood & tissue fluid 4. Cellular Respiration: production of ATP in cells

Mechanism of Breathing Assignment Design 2 separate flowcharts or one overall flowchart to illustrate the steps in inspiration and expiration. * Make sure you include ALL the terms indicated on your assignment handout!!