UNIT B: Human Body Systems Chapter 8: Human Organization Chapter 9: Digestive System Chapter 10: Circulatory System and Lymphatic System Chapter 11: Respiratory System: Section 11.1 Chapter 12: Nervous System Chapter 13: Urinary System Chapter 14: Reproductive System

Chapter 11: Respiratory System In this chapter, you will learn about the structure and function of the respiratory system. UNIT B Chapter 11: Respiratory System TO PREVIOUS SLIDE How would a narrowing and swelling of the airways affect the respiratory volumes? How do the typical treatments for asthma work to reduce the symptoms? Why is it so difficult to develop a cure for asthma? What are some of the normal defence mechanisms of the respiratory tract? Asthma is a disease in which the airways become constricted (narrowed) and inflamed (swollen), both of which can result in difficulty breathing. It is one of the most common chronic diseases in children. It is estimated that 10 to 15 percent of children in Canada have asthma.

11.1 The Respiratory System The main function of the respiratory system is to allow oxygen from the air to enter the blood and carbon dioxide from the blood to exit into the air. Ventilation, another term for breathing, includes both inspiration (inhalation) and expiration (exhalation). Air is conducted toward or away from the lungs by a series of cavities, tubes, and openings UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System

The respiratory system works with the circulatory system in the following homeostatic functions: External respiration: exchange of gases (oxygen and carbon dioxide) between the air and blood Transport of gases to and from the lungs and tissues Internal respiration: exchange of gases between the blood and tissue fluid UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System

UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System 11.1 The respiratory tract. a. The respiratory tract extends from the nose to the lungs, which are composed of air sacs called alveoli (see inset b). b. Gas exchange occurs between air in the alveoli and blood within a capillary network that surrounds the alveoli. Notice that the pulmonary arteriole is coloured blue—it carries O 2 -poor blood away from the heart to the alveoli. Then carbon dioxide leaves the blood, and oxygen enters the blood. The pulmonary venule is coloured red—it carries O 2 -rich blood from the alveoli toward the heart.

The Respiratory Tract Inspiration: air is filtered, warmed, and moistened as it moves along the respiratory tract Filtered by hairs in the nostrils, and by cilia in the mucus of nasal cavities and airways Warmed by heat given off by blood vessels close to the lining of the airways Moistened by the wet surface of airways Expiration: air cools and loses its moisture as it moves out of the respiratory tract Deposits moisture on the lining of the trachea and nose UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System

UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System Figure 11.2 Ciliated Cells. These cells line the interior of the nasal passages and upper respiratory tract.

The Nose The nose is the only external portion of the respiratory system. Air enters the nose through the nostrils Air is moistened and warmed in two nasal cavities that are lined with mucous membranes Nasal cavities are separated from the mouth by the palate, which is composed of the hard palate and soft palate UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System Figure 11.3 The path of air. Air passes through the nasal cavities and mouth to and from the upper and lower respiratory tracts. The trachea is part of the lower respiratory tract; the other organs are in the upper respiratory tract.

The Pharynx The pharynx is also known as the “throat.” Connects the nasal and oral cavities to the larynx Contains lymphatic tissues called tonsils that contain lymphocytes that protect against pathogens Allows for the passage of air and food UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System

The Larynx The larynx is called the voice box since it contains the vocal cords. Connects the pharynx to the trachea Composed of cartilage and dense connective tissue Allows for the passage of air (the glottis allows air into the larynx) A flap of tissue above the larynx, the epiglottis, prevents passage of food into lower respiratory tract UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System

UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System Figure 11.4 Placement of the vocal cords. Viewed from above, the vocal cords stretch across the glottis, the opening to the trachea. When air is expelled through the glottis, the vocal cords vibrate, producing sound. The glottis is narrow when we make a high-pitched sound, and it widens as the pitch deepens.

The trachea is commonly called the windpipe. Connects larynx with bronchi Composed of C-shaped cartilaginous rings Allows for the passage of air to bronchi Cleans, warms, and moistens air Mucous membrane lining contains goblet cells (produce mucus) and ciliated cells (sweep mucus and debris toward the pharynx) The Trachea UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System

UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System Figure 11.5 The surface of the trachea. A scanning electron micrograph shows that the surface of the mucous membrane lining the trachea consists of goblet cells and ciliated cells. The cilia sweep mucus and the debris embedded in it toward the pharynx, where they are swallowed or expectorated. Smoking causes the cilia to disappear, allowing debris to enter the bronchi and lungs.

The Bronchial Tree The trachea divides into the bronchi, which lead into the lungs. The bronchi branch into secondary bronchi that lead to bronchioles Each bronchiole leads to thin- walled air sacs called alveoli (site of gas exchange between air and blood) The components of the bronchial tree beyond the primary bronchi make up the lungs UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System

The Lungs The lungs are paired, cone-shaped organs that contain alveoli, airways, and blood vessels. At the base of the lungs is the diaphragm, a muscle involved in inspiration and expiration Each lung is covered with a thin membrane called a pleura o Secretes fluid so that it can slide freely against the pleura of the chest wall and diaphragm during inspiration and expiration UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System

The Lungs During inhalation, air enters the lungs by way of the bronchial tree and moves to the alveoli Gas exchange occurs between the air in an alveolus and the blood in the capillaries o Alveoli are covered with pulmonary surfactant, a film of lipoprotein that prevents the alveoli from closing so that inhaled air can enter UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System

UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System Figure 11.6 Gas exchange in the lungs. The lungs consist of portions of the bronchial tree leading to the alveoli. Each alveolus is surrounded by an extensive capillary network. Notice that the pulmonary artery and arteriole carry O 2 -poor blood (coloured blue) and the pulmonary vein and venule carry O 2 -rich blood (coloured red).

UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System

UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System

Check Your Progress 1.List the structures of the respiratory system. 2.Describe how the arrangement of the trachea, esophagus, larynx, and epiglottis prevents food from entering the trachea. 3.Describe the function of pulmonary surfactant. UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System

UNIT B TO PREVIOUS SLIDE Section 11.1 Chapter 11: Respiratory System