Respiratory System Describe the pathway of gas exchange from the external environment to the capillary bed and back out. Describe the structure and function of the lungs, bronchi, and the pleural coverings. Describe the various respiratory volumes and capacity, including how respiratory capacities are measured. List and explain the four events of respiration and the mechanics of breathing.

Learning Target #7 The cardiovascular system is useless without the respiratory system. – Respiration (breathing) allows for the exchange of oxygen and carbon dioxide

Blood Pathway Oxygen-Rich Blood Lungs Pulmonary veins Left atrium Left ventricle Aorta Body arteries Arterioles Capillary beds (site of gas exchange) Oxygen-Poor Blood Capillary beds (site of gas exchange) Venules Body veins Superior and inferior vena cava Right atrium Right ventricle Pulmonary arteries Lungs

Learning Target #8

Upper Respiratory Structures Nose Pharynx Larynx Trachea

Nose Provides airway Moistens and warms air Filters air Resonating chamber for speech Olfactory receptors

Nasal Conchae Increases turbulence of air 3 scroll-like structures Reclaims moisture on the way out

Larynx

Lower Respiratory Structures Primary bronchi Bronchioles Lungs Pleural coverings

Paired lungs occupy all thoracic cavity lateral to the mediastinum Mediastinum contains (mainly): heart, great blood vessels, trachea, main bronchi, esophagus

Chest X Rays

Lungs

Human Lungs

Effects of Smoking

Alveoli Made of simple squamous epithelium Site of gas exchange via capillaries

Surfactant *Type II cuboidal epithelial cells are scattered in alveolar walls *Surfactant is a detergent-like substance which is secreted in fluid coating alveolar surfaces – it decreases tension *Without it the walls would stick together during exhalation *Premature babies – problem breathing is largely because lack surfactant

Learning Target #9 Tidal volume = amount taken in and out in a normal breath Inspiratory reserve volume = amount over a normal breath that a person can forcibly inhale (take a deep breath…) Expiratory reserve volume = amount of a air that can be forcibly exhaled Residual volume = amount of air ALWAYS present in the lungs (so they don’t collapse) Vital capacity = total amount of exchangeable air (TV +IRV+ERV)

Lung Volumes

Learning Target #10 Events of Respiration: 1.Pulmonary ventilation = aka breathing 2.External respiration = gas exchange (oxygen- loading and carbon dioxide-unloading) 3.Respiratory gas exchange = use of the cardiovascular system to transport gases to and from body tissues 4.Internal respiration = gas exchange across the plasma membrane of body cells