Download 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