Lesson Overview

Lesson Overview The Respiratory System

Lesson Overview33.3 The Respiratory

System


Functions of the Respiratory System• picks up oxygen from the air [inhale]• releases carbon dioxide into the air [exhale]• respiration = process of gas exchange

between body and environment


Structures of Respiratory System:Nose & Nasal Cavity

• To keep lung tissue healthy:o Hairs lining the nasal cavity trapping large

particles o Incoming air is warmed in the inner nasal

cavity and sinuses o These areas also produce mucus that

moistens the air and catches even more dust particles.


Pharynx, Larynx, and Trachea • From the nasal cavity, air moves down into the:

o pharynx = (throat) passageway for both air & foodo Only air moves from the pharynx into the larynx =

(voicebox) contains elastic folds of tissue known as vocal cords When muscles pull the vocal cords together, the

air moving between them causes the cords to vibrate and produce sounds


Pharynx, Larynx, and Trachea o From the larynx, air moves into the trachea= windpipe

When you swallow food or liquid, a flap of tissue called the epiglottis covers the entrance to the larynx, ensuring that the food or liquid goes into the esophagus

Mucus produced in the trachea continues to trap inhaled particles

Cilia lining the trachea sweep both mucus and trapped particles away from the lungs toward the pharynx, where they can be swallowed or spit out



Bronchi and Bronchioles • From the trachea, air moves

into two large tubes in the chest cavity called bronchi. Each bronchus leads to one lung.

• Within each lung, the large bronchus divides into smaller bronchi, which lead to even smaller passageways called bronchioles.


Alveoli (Lungs) o The bronchioles continue to

branch until they end in tiny air sacs called alveoli Alveoli make up lung tissue

o Alveoli are grouped in clusters, like bunches of grapes. A network of capillaries surrounds the alveoli in order for gas exchange to occur

Lesson Overview The Respiratory SystemGas Exchange

• When air enters the lungs, oxygen dissolves in the moisture in alveoli and then diffuses across capillary walls into the blood o Oxygen diffuses in this

direction because the oxygen concentration is greater in the alveoli than it is in the blood

• Carbon dioxide diffuses from blood into the alveoli because its concentration is greater in the blood than it is in the alveoli


Inhalation [breathing in] • When you inhale, the diaphragm

muscle contracts and flattens. Muscles between the ribs also contract, raising the rib cage

• These actions increase the volume of the chest cavity and create a partial vacuum inside the cavity, which draws air into the lungs


Exhalation [breathing out]

• During exhalation, both the rib cage and the diaphragm relax, decreasing the volume of the chest cavity

• Air rushes out of the lungs


Exhalation • Exhalation is usually a passive

process, but to blow out a candle, speak, sing, or yell, you need more force provided by muscles between the ribs


Smoking and the Respiratory System


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Lesson Overview