THE RESPIRATORY SYSTEM

Respiratory System Transports gases between external environment and the internal gas exchange surfaces

Nasal Cavity Exposed to the air through nostrils Is lined with ciliated mucous membranes, which filter, warms and moistens the air

Pharynx Throat cavity where oral cavity and nasal cavity meet Food is prevented from entering the trachea by the epiglottis

Larynx Is the voice box Made mostly of cartilage Vocals cords are located here (2 pr of membranes that are stretched across the inside of the larynx) As air is breathed in and out the cords vibrate to make sounds

Trachea Tube lined with rings of cartilage (for strength and support) Lined with ciliated mucous membranes for trapping microscopic particles

Bronchi Tube which enters each lung Extends into each lung where it subdivides many times forming bronchioles

Alveoli Bronchioles end with alveoli Alveoli are small, moist, cuplike cavities which are surrounded by capillaries This is where the exchange of oxygen and carbon dioxide takes place

Oxygen is carried by the red blood cells as oxyhemoglobin The oxygen easily diffuses across cell membranes to be used during aerobic cellular respiration

Carbon dioxide in the plasma is carried in the form of the bicarbonate ion CO2 + H2O ----- H2CO3 ---------

Diaphragm A sheet of muscle which changes the size of the chest cavity

Mechanics of Breathing Mechanical process of taking air into and out of the lungs

Inhalation Air moves into the lungs The diaphragm moves down The volume of the chest cavity increases Pressure decreases and air moves in

Exhalation Air moves out of the lungs The diaphragm moves up The volume of the chest cavity decreases Pressure increases so air is forced out

Medulla Lower back part of the brain that regulates the breathing rate Breathing rate depends on the carbon dioxide level of the blood Works as a feedback mechanism to help maintain homeostasis