The Respiratory System Bio 20

THE RESPIRATORY TRACT The respiratory tract is what brings air from the atmosphere to the lungs RECALL - Your body needs oxygen from the air to undergo aerobic cellullar respiration to create energy There is both an upper and a lower respiratory tract

UPPER RESPIRATORY TRACT Air enters through the mouth and nostrils Nasal passages will warm, moisten and clean incoming air Are lined with cilia Air is warmed to protect later structures

The pharynx is the passageway for air into the respiratory system (also for food and water) epiglottis – flap that covers the glottis (opening to the trachea) when food is swallowed

The larynx is our voice box and is made from cartilage Contains vocal cords When you speak the muscles around the larynx contract drawing the vocal cords together

From the pharynx air enters the trachea The trachea is strengthened by cartilaginous arches This cartilage prevents the trachea from collapsing

LOWER RESPIRATORY TRACT The trachea will branch into two pathways called bronchi These bronchi lead to the left and right lungs Once they reach the lungs the bronchi split into even smaller tubes called bronchioles Both the bronchi and bronchioles are lined with cilia and mucus-producing cells

Each bronchiole ends with a bunch of tiny sacs called alveoli In the alveoli is where gas exchange between the lungs and the circulatory system takes place Each alveoli is surrounded by many capillaries

during inhalation the alveoli are bulb shaped when one exhales, the sacs collapse and the membranes touch need to have a lipoprotein layer to avoid staying stuck together respiratory distress syndrome

Our lungs are divided into lobes; the right lung has 3 lobes and the left has 2 lobes (to leave space for the heart) The lungs are surrounded by a membrane called the pleural membrane which is found on the outer surface of the lung and the inner wall of the chest cavity these membranes stick to each other

BREATHING AND RESPIRATION Air needs help to flow in and out of the lungs The diaphragm and the intercostal muscles (rib muscles) help the air move in and out These two structures work together during inhalation and exhalation They control the air pressure in the lungs

INHALATION To help us breathe in the intercostal muscles and the diaphragm contract This increases the space in the chest cavity which decreases the air pressure around the lungs The lungs are drawn outwards and the air pressure in the lungs decreases Air moves from an area of high pressure to low pressure so moves from the environment to the lungs

INHALATION

EXHALATION The intercostal muscles and the diaphragm relax which makes the space in the chest cavity smaller This causes the lungs size to decrease which increases the air pressure inside the lungs The pressure is now greater inside the lungs than in the environment so the air wants to move out

EXHALATION

Exhalation The intercostal muscles and the diaphragm relax which makes the space in the chest cavity smaller This causes the lungs size to decrease which increases the air pressure inside the lungs The pressure is now greater inside the lungs than in the environment so the air wants to move out

GAS EXCHANGE AND RESPIRATION Respiration is a combination of external and internal respiration External respiration happens in the lungs where gases are exchanged between the alveoli and the blood in capillaries The air in the alveoli has a higher O2 content than the air in the blood so O2 diffuses into the blood The air in the blood has a higher CO2 content than the air in the alveoli so CO2 diffuses into the alveoli

Internal respiration occurs between the blood and tissue cells in our body O2 moves into the tissues and CO2 moves into the blood

Most oxygen in the blood is carried by hemoglobin which is only found in red blood cells Very little carbon dioxide, 23%, is carried by hemoglobin (carboaminohemoglobin) Most carbon dioxide is carried in the blood as bicarbonate ion (HCO3-), 70% The final 7% is carried in the plasma

Respiratory Volume Spirograph – graph representing the amount of air that moves into and out of the lungs

Tidal volume – volume of air inhaled and exhaled during a normal breath at rest Inspiratory reserve volume – additional volume of air that can be taken in beyond a tidal inhalation Expiratory reserve volume – additional volume of air that can be forced out beyond a tidal inhalation Vital capacity = Tidal volume + inspiratory reserve volume + expiratory reserve volume Residual volume – amount of gas remaining in respiratory system after full exhalation

GAS EXCHANGE AND RESPIRATION Respiration is a combination of external and internal respiration External respiration happens in the lungs where gases are exchanged between the alveoli and the blood in capillaries The air in the alveoli has a higher O2 content than the air in the blood so O2 diffuses into the blood The air in the blood has a higher CO2 content than the air in the alveoli so CO2 diffuses into the alveoli

Respiratory Disorders

Tonsillitis Infection of the tonsils Viral infection is more common Tonsils can be removed through surgery

Laryngitis Inflammation of the larynx Caused by viral infection, allergies and over-straining of the voice Reduces the ability to speak normally

Bronchitis Inflammation of the bronchi; filled with mucus Bacterial infection; treated by antibiotics Exposure to irritants over a long period of time can kill the cilia causing the bronchi to be even more inflammed

Pneumonia Alveoli fills with liquid and becomes inflamed Interferes with gas exchange Bacterial and viral infection

Pleurisy Swelling and irritation of the pleura Caused by viral or bacterial infections; a blood clot or cancer Sharp, stabbing pain in the chest

Emphysema Walls of the alveoli break down and lose their elasticity Affects gas exchange; breathing becomes labored Caused by smoking; permanent and incurable

Cystic Fibrosis Genetic condition Causes there to be an increase in mucus and liquids in the lungs Contract many infections Treated with medications, an inhaler, gene therapy

Asthma Obstructive lung disease of the bronchi and bronchioles Makes breathing difficult No cure; treated with inhalers and various medications

Lung Cancer Uncontrolled and invasive growth of abnormal cells Reduce gas exchange Most types of lung cancer are caused by smoking