Respiratory System Finals PDF

Lesson Overview The Respiratory System Lesson Overview 27.2 Human Systems I The Respiratory System Lesson Overview The Respiratory System...

Lesson Overview The Respiratory System Lesson Overview 27.2 Human Systems I The Respiratory System Lesson Overview The Respiratory System Structures of the Respiratory System What is the function of the respiratory system? The human respiratory system picks up oxygen from the air we inhale and releases carbon dioxide into the air we exhale. Lesson Overview The Respiratory System Structures of the Respiratory System For organisms, respiration means the process of gas exchange between a body and the environment. The human respiratory system picks up oxygen from the air we inhale and releases carbon dioxide into the air we exhale. The circulatory system links the exchange of gases in the lungs with our body tissues. The respiratory system consists of the nose, pharynx, larynx, trachea, bronchi, and lungs. Lesson Overview The Respiratory System Nose To keep lung tissue healthy, air entering the respiratory system must be filtered, moistened, and warmed. Hairs lining the entrance to the nasal cavity start the filtering process by trapping large particles. Incoming air is warmed in the inner nasal cavity and sinuses. These areas produce mucus that moistens the air and catches even more dust particles. Lesson Overview The Respiratory System Pharynx, Larynx, and Trachea Air moves through the nose to a cavity at the back of the mouth called the pharynx, or throat, which serves as a passageway for both air and food. Air moves from the pharynx into the trachea, or windpipe. When you swallow food or liquid, a flap of tissue called the epiglottis covers the entrance to the trachea, ensuring that the food or liquid goes into the esophagus. Lesson Overview The Respiratory System Pharynx, Larynx, and Trachea Between the pharynx and the trachea is the larynx, which contains two highly elastic folds of tissue known as the vocal cords. When muscles pull the vocal cords together, the air moving between them causes the cords to vibrate and produce sounds. Lesson Overview The Respiratory System Pharynx, Larynx, and 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 The Respiratory System Lungs From the trachea, air moves into two large tubes in the chest cavity called bronchi. Each bronchus leads to one lung. Within each lung, the large bronchus divides into smaller bronchi, which lead to even smaller passageways called bronchioles. Bronchi and bronchioles are surrounded by smooth muscles, controlled by the autonomic nervous system, that regulate the size of air passageways. Lesson Overview The Respiratory System Lungs The bronchioles continue to divide until they end at a series of tiny air sacs called alveoli. Alveoli are grouped in clusters, like bunches of grapes. A network of capillaries surrounds each alveolus. Lesson Overview The Respiratory System Gas Exchange When air enters alveoli, oxygen dissolves in the moisture on their inner surface and then diffuses across thin capillary walls into the blood. Oxygen diffuses in this direction because the oxygen concentration is greater in the alveoli than it is in the blood. Carbon dioxide diffuses from blood into the alveoli because its concentration is greater in the blood than it is in the air in the alveoli. Lesson Overview The Respiratory System Transport Diffusion of oxygen from alveoli into capillaries is a passive process that stops when oxygen concentration in the blood and alveoli is the same. Hemoglobin actively binds to dissolved oxygen, removing it from plasma and enabling diffusion from the alveoli to continue. Hemoglobin binds with so much oxygen that it increases blood’s oxygen-carrying capacity more than 60 times. When carbon dioxide diffuses from body tissues to capillaries, most of it enters red blood cells and combines with water, forming carbonic acid. The rest of it dissolves in plasma or binds to hemoglobin and proteins in plasma. These processes are reversed in the lungs, where carbon dioxide is released into alveoli and exhaled Lesson Overview The Respiratory System Breathing What mechanisms are involved in breathing? Movements of the diaphragm and rib cage change air pressure in the chest cavity during inhalation and exhalation. Lesson Overview The Respiratory System Inhalation The lungs are sealed in two sacs, called pleural membranes, inside the chest cavity. At the bottom of the chest cavity is a large dome-shaped skeletal muscle known as the diaphragm. Lesson Overview The Respiratory System Inhalation When you inhale, the diaphragm contracts and flattens. Muscles between the ribs also contract, raising the rib cage. These actions increase the volume of the chest cavity and create a partial vacuum inside the cavity. That means a pressure less than the atmospheric pressure. Atmospheric pressure fills the lungs as air rushes into the breathing passages. Lesson Overview The Respiratory System Lesson Overview The Respiratory System Exhalation During exhalation, both the rib cage and the diaphragm relax, decreasing the volume of the chest cavity and making air pressure in the chest cavity greater than atmospheric pressure. Air rushes back out of the lungs. Lesson Overview The Respiratory System Exhalation Exhalation is usually a passive process, but to blow out a candle, speak, sing, or yell, you need more force than passive exhalation provides. The extra force is provided by muscles between the ribs and abdominal muscles, which contract vigorously as the diaphragm relaxes. Lesson Overview The Respiratory System Breathing and Homeostasis You have some conscious control over your breathing—when you swim or play an instrument, for example—but breathing is not purely voluntary. Your nervous system has final control of your breathing muscles whether you are conscious or not. Lesson Overview The Respiratory System Breathing and Homeostasis Breathing is initiated by the breathing center in the part of the brain stem called the medulla oblongata. Sensory neurons in or near the medulla and in some large blood vessels gather information about carbon dioxide levels in the body and send the information to the breathing center. When stimulated, the breathing center sends nerve impulses that cause the diaphragm and chest muscles to contract, bringing air into the lungs. Lesson Overview The Respiratory System Effects on the Respiratory System 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 and hardens the wall of arteries leading to cardiac arrest. Addictive since it releases the dopamine in the brain. Carbon monoxide is a poisonous gas that blocks hemoglobin from binding with oxygen, thus interfering with oxygen transport in blood. Tar contains at least 60 compounds known to cause cancer.