Chapter 13 Respiratory System Anatomy and Physiology

13.1 Respiratory functional anatomy The organs of the respiratory system include the nose, pharynx, larynx, trachea, bronchi and the lungs

13.1 Respiratory functional anatomy The nose is the only externally visible part of the respiratory system When breathing air enters through the external nares (nostrils) and enters the nasal cavity (which is divided by the septum) The nasal cavity is lined with mucosa, and also the olfactory receptors are located there The palate separates the nasal and oral cavities The bone supported anterior section is called the hard palate and the unsupported posterior section is called the soft palate

13.1 Respiratory functional anatomy The nasal cavity is surrounded by paranasal sinuses They function to lighten the skull, allow for resonance of speech and they produce mucus, which drains into the nasal cavities Pharynx A muscular passageway for food and air that is about 5 inches long Commonly called the throat It extends from the nasal cavity There are three regional divisions; nasopharynx, oropharynx and laryngopharynx There are tonsils found in this region, called the pharyngeal tonsils or adenoids (they are found in other places too)

13.1 Respiratory functional anatomy Larynx This is the voice box Formed by 8 rigid hyaline cartilages (the largest called the thyroid cartilage, also called the Adam’s apple) and a spoon shaped flap of elastic cartilage called the epiglottis The epiglottis protects the superior opening of the larynx when we are swallowing The vocal cords are formed by mucus membranes, the passageways between the folds is called the glottis

13.1 Respiratory functional anatomy Trachea It is about 4 inches long and is fairly rigid due to the C shaped hyaline cartilage The C are open in the back, where the esophagus abuts the trachea, allowing the esophagus to expand as we swallow food It is lined with ciliated mucosa Main bronchi The right and left bronchi are branches off the trachea Air at this point is clean, moist and warm

13.1 Respiratory functional anatomy

13.1 Respiratory functional anatomy Lungs They are large organs that occupy most of the thoracic cavity, except the mediastinum, where the heart is located The apex is the superior, top portion of the lungs The base of each lung rests on the diaphragm Each lung is covered by a membrane called the pulmonary or visceral pleura The thoracic cavity itself is lined with a membrane called the parietal pleura The two membranes have a slippery fluid between them that cuts down on friction called pleural fluid

13.1 Respiratory functional anatomy The bronchi continue to branch as they go inside the lung tissue The smallest airways, called bronchioles do not have reinforcing cartilage, all the other bronchi do Each bronchiole ends in an alveoli; or cluster of air sacs The respiratory zone includes the end of the a bronchiole and the alveoli All the other bronchi are considered conducting zone structures The respiratory membrane is the air-blood barrier and it consists of the capillary walls fused to the alveolar membrane; carbon dioxide and oxygen are passed between the air and blood by diffusion

13.2 Respiratory Physiology Four events take place to accomplish the intake of oxygen and the disposal of carbon dioxide; collectively they are called respiration 1. Pulmonary Ventilation: also called breathing; is the movement of air in and out of the lungs 2. External respiration: occurs as gases (CO2 and O2) are exchanged between the pulmonary blood and the alveoli 3. Respiratory gas transport: the movement of the gases through the blood stream 4. Internal respiration: exchange of gases between the blood in capillaries and tissue cells

13.2 Respiratory Physiology Mechanics of Breathing Basically volume changes lead to pressure changes which lead to the flow of gases to equalize pressure There are two phases to breathing; inspiration and expiration

13.2 Respiratory Physiology Inspiration occurs when the external intercostal muscles between the ribs contract along with the diaphragm to increase the volume of the thoracic cavity This increase in volume causes a decrease in pressure which means air rushes into the lungs (God’s design is so amazing!!!)

13.2 Respiratory Physiology Expiration occurs because the ribs and diaphragm relax, decreasing volume which increases pressure, causing air to flow out. It is a passive process in healthy people

13.2 Respiratory Physiology Nonrespiratory Air Movements 1. Cough Sneeze Crying Laughing Hiccups Yawn All are explained on page 437

13.2 Respiratory Physiology Control of Respiration The neural centers that control respiratory rhythm and depth are located in the medulla and pons The medulla sets the basic rhythm of breathing, while the pons appears to smooth out that rhythm The normal respiratory rate is referred to as eupnea

13.2 Respiratory Physiology Factors that influence respiratory rate and depth 1. Physical factors: talking, coughing, exercising, etc 2. Volition: (conscious control)we control our breathing for swimming, singing, etc, but we can only control it so much. If you hold your breath long enough, the involuntary controls take over 3. Emotional factors: watching horror movies, etc 4. chemical factors: mostly the levels of CO2 and O2

13.3 Respiratory Disorders COPD: Chronic Obstructive Pulmonary Disease  is a progressive disease that makes it hard to breathe In COPD, less air flows in and out of the airways because of one or more of the following: The airways and air sacs lose their elastic quality. The walls between many of the air sacs are destroyed. The walls of the airways become thick and inflamed. The airways make more mucus than usual, which can clog them.

13.3 Respiratory Disorders

13.3 Respiratory Disorders Chronic bronchitis is a serious long-term disorder that often requires regular medical treatment. Chronic bronchitis is one of two main types of a COPD. The other main form of COPD is emphysema. Both forms of COPD make it difficult to breathe.

13.3 Respiratory Disorders Emphysema Emphysema is a long-term, progressive disease of the lungs that primarily causes shortness of breath due to over-inflation of the alveoli  In people with emphysema, the lung tissue is impaired or destroyed