Respiratory System

1. Respiratory System

2. Parts • The respiratory system is divided into two parts: • Upper respiratory tract • Lowerrespiratory tract

3. Major Organs and Functions • Nose:The only Externally visible part of the respiratory system. • During the process of breathing, air passes through the external nares (nostrils) • The interior of the nose is called the nasal cavity, which is divided by the midline/nasal septum. • The Respiratory Mucosa lining the nasal cavity contains olfactory receptors which provide for the sense of smell. • Beneath the mucosa lies a network of thin walled veins, which function to warm and moisten air as it enters the nose. Also the mucosa traps incoming bacteria which prevents colds and sicknesses.

4. Pharynx:A muscular passageway for food and air, which is often referred to as the throat. • The air enters thenasopharynxfrom the nasal cavity and continues through theoropharynxand laryngopharynxto enter the esophagus below. The tonsils are located in the pharynx and are just clusters of lymphatic tissues • Larynx:Voice box which conducts air and food into proper pathways and plays an important role in speech. • It is made up of eight hyaline cartilages, thethyroid cartilagebeing the largest. It protrudes anteriorly and is called the Adams Apple. The epiglottis guides the air throughout the superior opening of the larynx.

6. -Bronchi: Two air tubes that branch off of the trachea enter the lungs and spread into treelike fashion into smaller tubes called bronchial tubes. -Alveoli: Tiny air sacs within the lungs where the exchange of oxygen and carbon dioxide takes place. -They are at the end of the bronchioles, running from the bronchi into the lobes of the lung.

7. Diaphragm: is a shelf of muscle extending across the bottom of the ribcage. • In order to draw air into the lungs, the diaphragm contracts, thus enlarging the thoracic cavity and reducing intra-thoracic pressure. When the diaphragm relaxes, air is exhaled.

8. Trachea:(Also called windpipe), is an important part of the vertebrate respiratory system. It is a bony tube that connects the nose and mouth to the lungs. • When an individual breathes, air is taken into the lungs for respiration. The air flows through the windpipe. Because of its primary function, any damage incurred to the trachea can be potentially life-threatening.

9. Lungs: main organs of the respiratory system. In the lungs oxygen is transported to the body and carbon dioxide is removed. • Structure: • Each lung is between 10 and 12 inches long. The left lung is divided into two sections, or lobes: superior and inferior. The right lung is somewhat larger than the left lung and is divided into three lobes: superior, middle, and inferior. The lungs are covered by a protective membrane called the pulmonary pleura. • The walls of the thoracic cavity are lined with parietal pleura. The pleural membranes function to produce pleural fluid, which is a slippery secretion which permits the lungs to glide easily over the thorax during breathing movements and allow the two pleural layers to cling to one and other. The pleurae have the ability to slide across each other, but resist being pulled apart. The position of tightly adhering pleural membranes is essential for normal breathing.

10. Lungs • Function: The main function of your lungs is respiration. • Each day, you take about 23,000 breaths, which bring almost 10,000 quarts of air into your lungs. The air that you breathe in contains several gases, including oxygen that your cells need to function. With each breath, your lungs add fresh oxygen to your blood, which then carries it to your cells.

11. How do you breathe? Breathing: • a mechanical process that depends on volume changes that occur in the thoracic cavity • breathing works by making the rib cage bigger, the pleural layers slide over each other and the pressure in the lung is decreased, so air is sucked in. • Breathing out does the reverse, the cage collapses and air is expelled. • The diaphragm is the main component. • When is contracts, it flattens and increases the space above it. • During relaxation, the abdominal contents push it up again. Voice Production: • Air pressure from the lungs travels up through the trachea, larynx, and pharynx. • The vocal folds in the larynx vibrate, which creates fluctuations in air pressure called sounds waves. • The vocal tract resonates and modifies the waves to match the shape of the jaw, lips, tongue, soft palate, and other vocal organs. This creates regions and differentiation in sound. • The openings of the mouth and nose release the sound to the external environment,

12. Oxygen and Carbon Dioxide transportation in the blood The Major function of Respiratory system is to supply the body with oxygen and to dispose of Carbon Dioxide.  • The walls of alveoli are a single, thin layer of squamous epithelial cells (a sheet of tissue paper is much thicker) • Alveolar Pores connect neighboring air sacs and provide alternate routes for air to reach alveoli. • External surfaces of alveoli are covered with pulmonary capillaries. • Together, alveolar and capillary walls and their fused basement membranes construct the respiratory membrane (air-blood barrier), which has gas (air) flowing past on one side and blood flowing past on the other side. ** • Gas exchanges occur by a simple diffusion through the respiratory membrane- oxygen passing from the alveolar air into the capillary blood and carbon dioxide leaving the blood to enter the gas-filled alveolus. • Total gas exchange surface provided by the alveolar walls estimated = 50-70 square meters. (40 times greater than surface area of skin.)

13. Respiratory Volume • There are many factors that influence lung capcity. • Size, age, sex, physical condition, ect. • Tidal Volume (TV) is the amount of quiet breathing into and out of the lungs with each breath (500mL normally) • Inspiratory Reserve Volume (IRV): The amount of air that can be taken in forcibly over the tidal volume. (2100-3200mL normally) • Expiratory Reserve Volume (ERV): The amount of air that can be forcibly exhaled after a tidal expiration. (1200mL normally) • Residual Volume: The amount of air still remaining in the lungs that cannot be voluntarily expelled (1200mL normally) It is important because it permits gas exchange to continue between breaths and keeps alveoli open. .

14. Lung Capacities • Respiratory Volumes are measured with a spirometer. • Vital Capacity (VC): The total amount of exchangeable air. It is the sum of the TV, IRV, and ERV. (4800 in healthy young males) • Dead Space Volume: The air that enters the respiratory tract but does not reach the alveoli. (Usually about 150mL, the other 350 reaches the alveoli)

15. External v Internal Respiration • External Respiration is the exchange of gases between the alveoli and the blood, while internal respiration is gas exchange between the systemic capillaries and he tissue cells.

16. Inspiration v Expiration • Inspiration, or inhalation, is the process by which air flows into the lungs. It involves the contraction of the diaphragm and external intercostals, which in turn increases the volume of the thoracic cavity. Consequently, the lungs and the gases within the lungs, expand to fill the new space. This effect produces a partial vacuum that sucks the air into the lungs until the intrapulmonary pressure is equal to atmospheric pressure. • Expiration, or exhalation, is the process that expels air out of the lungs. In healthy people, this process is very passive and relies mostly on the elasticity of the lungs rather than muscle contractions. After inspiration takes place, the muscles resume their original positions, forcing the ribcage to descend and the lungs to recoil. This causes the thoracic and intrapulmonary volumes decrease. As a result, the gases inside the lungs are forced more closely together and the intrapulmonary pressure rises to a point higher than atmospheric pressure, The gases then flow out of the lungs to stabilize pressures inside and outside of the lungs.

17. Nervous Control of Respiration • Voluntary • Phrenic and Intercostal Nerves • In the brain, breathing is controlled by neural centers called the ponsand medulla • Medulla- sets basic rhythm; contains a self-exciting inspiratory center as well as other respiratory centers • Pons- smoothes out basic rhythm of inspiration and expiration set by medulla • Impulses go back and forth b/w the two • Normal breathing rate = 12-15 respirations/min. (eupnea) • In case of overinflation of bronchioles and alveoli, impulses are sent from the stretch receptors to the medulla by the vagus nerves (inspiration ends, expiration occurs) • Hyperpnea-brain sends more impulses to resp. muscles to breathe (exercise, etc.) • Volition- conscious control • Emotional factors(fear, love, etc.) • Chemical factors- • Levels of co2 and o2 in blood (medulla)

18. Pressure Relationship of Breathing • Inspiration- taking in air (inhalation) • As the diaphragmand external intercostals contract, thoracic cavity gets bigger from top to bottom (diaphragm flattens out=bottom down, external intercostals contract= top up) • Sternum thrusted forward (increases front to back) • Lungs expand with thoracic cavity • Gas has more room to move; PRESSURE DECREASES • Body seeks to make intrapulmonary pressure equal to atmospheric pressure by inhaling more gas until lungs are full • Expiration- letting air out (exhalation) • Inspiratory muscles relax; thoracic and intrapulmonary volume decreases • Gases in lungs are forced more closely together; intrapulmonary pressure is greater than atmospheric pressure • Gases flow out to equalize pressure • Usually effortless unless resp. passages are narrowed (asthma, pneumonia, bronchitis, etc.); in forced expiration, internal intercostals muscles depress rib cage and abs contract to force air out by squeezing abdominal organs against diaphragm • The intrapleural pressure is always negative; prevents collapse of lungs • Protective Mechanisms • cilia and mucous to trap dust, bacteria, etc. • coughing (clears lower respiratory passageways), sneezing (clears upper respiratory passageways) • movement of larynx blocks food from entering trachea and directs it to esophagus

19. Respiratory Diseases • Infectionby viruses and bacteria: range from the common cold to the flu virus and Streptococcus(strep throat) • Many upper respiratory tract problems: • Epistaxis • Laryngitis • Pharyngitis • Rhinitis • Sinusitis • Sleep apnea • tonsilitis

20. Respiratory Diseases • Emphysema: usuallycaused by smoking • Can also be inherited (deficiency of alpha-I antitrypsin [AAT] protein) • Fourth leading cause of death in U.S. • How it works: • Damage to alveoli- Over-inflated alveoli fuse to become an enlarged alveoli. This results in less surface area for the normal gas exchange and blood oxygenation. Damage to the surfactant coating the alveoli causes a loss of elasticity. “Stale” air is never replaced by fresh air, and eventually alveoli can collapse, trapping the air. • Symptoms: breathlessness, barrel chest, weight loss, problems with breathing out

21. Respiratory Diseases • Emphysema(cont): • Treatment: • 1. surfactants to replace those lost • 2. oxygen therapy to oxygenate tissues • 3. treatment of symptoms • Pneumonia: an inflammation of the lungs caused by an infection or an injury in which the alveoli fill with fluid • Two to three million people affected in U.S. each year; out of these, about 40,000 to 70,000 people die • Proper gas exchange can not occur when fluid such as mucus or pus is present • Causes? • Bacteria, viruses, mycoplasmas, fungi, and various chemicals • Lead to a variety of types and strengths of pneumonia

22. Respiratory Diseases (cont) • Pneumonia (cont): • Symptoms: • severe shaking chill, high fever, cough, shortness of breath, rapid breathing, chest pains • Treatment: • antibiotics for the bacterial form; rest, drink fluids; anti-inflammatory meds • Preventative measures: • good hygiene, flu vaccination, don’t smoke tobacco Normal lungs Lungs with pneumonia

23. Respiratory Diseases (cont) • Tuberculosis: a bacterial infection of the lungs caused by the Myobacterium tuberculosis bacteria • Over-stimulates the inflammatory immune response, destroying lung tissue • Symptoms: a cough lasting 3 or more weeks, coughing up blood or mucus, fever and chills, night sweats; can be very deadly • Treatments: • Active: antibiotic treatment over a period of 6-12 months; if second occurrence (MDR-TB), requires special drugs that often have extreme side effects • Latent: isoniazid can prevent TB from becoming active • A vaccine for specifically Bacille Calmette-Guerin (BCG) strain

24. 'Respiratory system," Hillendale Health. May 3, 2007. <http://hes.ucf.k12.pa.us/gclaypo/repiratorysys.html#Lungs> • "Anatomy of Respiratory System," Ohio State University Medical Center. May 3, 2007 <http://medicalcenter.osu.edu/patientcare/healthinformation/diseasesandconditions/respiratory/about/anatomy/> • "Oxygen Delivery System," The Franklin Institute. May 3, 2007. <http://www.fi.edu/biosci/systems/respiration.html> • "How the Lungs Work," National Heart Lung and Blood Institute. May 3, 2007. <http://www.nhlbi.nih.gov/health/dci/Diseases/Copd/Copd_HowLungsWork.html> • Ballard, Dr. Carol. The Lungs and Breathing. Farmington Hills, MI: Kidhaven Press, 2005. • Marieb, Elanie N. Essentials of Human Anatomy & Physiology. San Francisco, CA: Daryl Fox, 2003. • "Lung Toxicology Problem Set," The University of Arizona. 1997. May 7, 2007. http://www.biology.arizona.edu/chh/problem_sets/lung_toxicology/03t.html