Lesson Overview Lesson Overview The Respiratory System -Identify the structures of the respiratory system and describe their functions. -Describe gas exchange. -Describe how breathing is controlled. -Describe the effects of smoking on the respiratory system.

Lesson Overview Lesson Overview The Respiratory System Structures of the Respiratory System The respiratory system consists of the nose, pharynx, larynx, trachea, bronchi, bronchioles and alveoli. Bronchi, bronchioles and alveoli are contained within the lungs.

Lesson Overview Lesson Overview The Respiratory System Nose To keep lung tissue healthy, air entering the respiratory system must be filtered, moistened, and warmed; this all happens in the nasal cavity or nose. Hairs lining the entrance to the nasal cavity filter and trap large particles.

Lesson Overview Lesson Overview The Respiratory System Pharynx and Trachea Air moves through the nose to a cavity at the back of the mouth called the pharynx. Air moves from the pharynx into the trachea, or windpipe. A flap of tissue called the epiglottis covers the entrance to the trachea.

Lesson Overview Lesson Overview The Respiratory System Larynx Between the pharynx and the trachea is the larynx, which contains two highly elastic folds of tissue known as the vocal cords.

Lesson Overview Lesson Overview The Respiratory System Trachea 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.

Lesson Overview Lesson Overview The Respiratory System Into the Lungs From the trachea, air moves into two large tubes called bronchi. Each bronchus leads to one lung. Within each lung, the large bronchus divides into smaller passageways called bronchioles.

Lesson Overview Lesson Overview The Respiratory System Within the Lungs The bronchioles continue to divide until they end at a series of tiny air sacs called alveoli. A network of capillaries surrounds each alveolus.

Lesson Overview Lesson Overview The Respiratory System Gas Exchange Gas exchange happens at the alveoli in the lungs by diffusing across the thin capillary walls into the blood.

Lesson Overview Lesson Overview The Respiratory System Breathing is a NEGATIVE FEEDBACK mechanism Any automatic response your brain directs to bring the function of an organ or system back to within the normal range is considered negative feedback. Remember that the brain registers CO2 levels in the blood to modify the rate of breathing.

Lesson Overview Lesson Overview The Respiratory System Why is Smoking Bad? Three of the most dangerous substances in tobacco smoke are nicotine, carbon monoxide and tar. Nicotine is an addictive stimulant that increases heart rate and blood pressure. Carbon monoxide is a poisonous gas that acts as a competitive inhibitor by binding to hemoglobin in place of oxygen.

Lesson Overview Lesson Overview The Respiratory System Smoking’s Effects on the Respiratory System Tobacco smoke paralyzes cilia in the trachea, allowing inhaled particles to stick to enter the lungs.

Lesson Overview Lesson Overview The Respiratory System Diseases Caused by Smoking Chronic Bronchitis ~ In chronic bronchitis, the bronchi become inflamed and clogged with mucus. Emphysema ~ Long-term smoking can lead to emphysema, the loss of elasticity and eventual breakdown of lung tissue. Lung Cancer ~ Lung cancer is particularly deadly because, by the time it is detected, it usually has spread to other areas of the body.