11.2-The Human Respiratory System: A Closer Look SBI3U1

The Human Respiratory Tract is divided into: Upper & Lower Tract

Nasal Cavity Inside the nose Lined with mucous membrane Air is warmed and moistened Mucus and Cilia (tiny hairs) trap foreign particles such as dust, dirt or debris

Pharynx A.k.a.“throat” Common to both digestive and respiratory systems At the bottom is the epiglottis (open for breathing/closed for eating)

Larynx A.k.a “voicebox” Made of cartilage Used for sound production Vocal cords are pulled together when air is being expelled to cause vibrations / sound.

Trachea Flexible tube made of semicircular loops of cartilage Approx. 10 -12 cm in length Splits into two branches- bronchi

Bronchi Branch off the trachea and enters each lung Conducts the air into lungs

Lungs Notice that the Right lung has 3 lobes, left lung has 2 lobes Space between the pleural membrane and the lung is filled with fluid Pleural membrane surrounds each lung. Outer layer is attached to the chest wall and inner layer to the surface of the lung

Bronchioles & Alveoli Bronchioles: microscopic tubules that branch out from the bronchi in each lung Alveoli: tiny air sacs at the end of the bronchioles, surrounded by capillaries (tiny blood vessels) for gas exchange

Capillaries There are about 500 million alveoli per lung. A network of capillaries surrounding each alveolus. The walls of the alveoli and the walls of the capillaries are only one cell thick so that gas exchange can occur quickly by diffusion.

Gas Exchange The air that enters the alveoli after inhalation has a higher concentration of O2 than the alveolar blood. Thus, O2 diffuses out of the alveoli and into the blood. CO2 is exchange from blood into the alveoli where concentration of CO2 is higher in the blood.

Transportation of Gases in the Blood Oxygen-About 99% O2 that reaches cells is carried by hemoglobin, a protein in red blood cells. Carbon dioxide-About 23% of CO2 is carried by hemoglobin, while the remaining is carried in the blood fluids.

Homework Read and make notes 11.2 Comeplete pg. 454 # 1-3, 5-7, 9-13