The Human Respiratory System General l The respiratory

The Human Respiratory System

General l The respiratory passageways allow air to pass directly into the tissues of the body. l Air entering the respiratory system must be warmed, moistened and filtered. l Dust particles are trapped by hairs lining the nasal cavity.

General l Some cells of the respiratory system produce a thin layer of mucus. l Mucus moistens the air and traps smoke and dust particles. l Cilia sweep the trapped particles from the lungs toward the pharynx l That mucus is swallowed or spit out.

Pathway l Air moves through the nose to a tube at the back of the mouth called the pharynx, or throat. l The pharynx is a passageway for both air and food.

Pathway Cont… l Air moves from the pharynx into the trachea, or windpipe l A piece of cartilage (epiglottis) covers the entrance to the trachea when you swallow. l At the top of the trachea is the larynx, which contains the vocal cords. l When muscles pull the vocal cords together, the air moving between them causes vibrations that produce sounds.

Pathways Cont… l From the larynx, air passes through the trachea into two large passageways called the bronchi l Each bronchus leads to one of the lungs l Within each lung, each bronchus divides into smaller bronchi, which divide into smaller bronchioles. l The bronchioles divide until they reach a series of dead ends called alveoli.

Alveoli l Alveoli are grouped in little clusters (like grapes) l A network of capillaries (small blood vessels) surrounds each alveolus. l This is the site of gas exchange.

Gas Exchange l Oxygen dissolves in the moisture on the inner surface of the alveoli and then diffuses across capillaries into the blood l Carbon dioxide in the bloodstream diffuses across the membrane into the alveolus.

Gas Exchange l Process of gas exchange is very efficient. l Air inhaled contains 21% oxygen and 0. 04% carbon dioxide l Air exhaled contains less than 15% oxygen and 4% carbon dioxide.

Hemoglobin l Oxygen carrying protein in the blood l Hemoglobin binds with oxygen. l Hemoglobin increases the carrying capacity of the blood 60 x. l Without hemoglobin, you would need 300 L of blood.

Breathing l Movement of air into and out of lungs l Air pressure is responsible, not muscles. l Lungs are sealed in two sacs (pleural membranes) l At the bottom of the respiratory cavity is the diaphram.

Breathing l When you breath in, the diaphram contracts and expands the volume of the chest cavity. l This creates a vacuum like atmosphere because the chest cavity is sealed. l Air gets sucked into the lungs.

Why Smoking is Bad l The upper part of the respiratory system is able to filter dust and dirt that could damage the lungs l Smoking damages and destroys this ability to filter.

Why Smoking is Bad l Nicotine, carbon monoxide and tar are 3 of the most dangerous substances in cigarettes. l Nicotine-stimulant that increases heart rate and blood pressure l Carbon monoxide-poisonous gas that blocks transport of oxygen by hemoglobin l Tar-contains compounds that cause cancer.

Why Smoking is Bad l The three compounds just discuss also paralyze cilia when inhaled in the respiratory system. l Without cilia, inhaled particles stick to the walls of the respiratory system or enter the lungs l Mucus becomes trapped which explains smokers cough. l Smoking causes inflammation of the respiratory system which reduces airflow to alveoli.

Why Smoking is Bad l The left shows a healthy lung l The right shows a smoker’s lung

Diseases Caused by Smoking l Chronic bronchitis – – Bronchi become clogged with mucus and swollen. People have a hard time doing daily tasks l (ex. Walking up stairs)

Diseases Caused by Smoking l Emphysema – – – Loss of elasticity in lungs Makes breathing difficult People cannot get enough oxygen to the body tissues and cannot get rid of carbon dioxide produced by cellular respiration.

What Does Emphysema Look Like?