Respiratory System PG 167 Respiratory System Functions One

Respiratory System

PG. 167

Respiratory System Functions �One of the largest organ systems in the body 1, 500 miles of airways and almost 1, 000 miles of capillaries in the lungs Surface area of lungs is 80 x greater than surface area of skin �Exchange of oxygen and carbon dioxide through respiration External, internal and cellular respiration �Production of sound Larynx contains vocal cords

Respiration �External respiration/breathing Exchange of oxygen and carbon dioxide between the lungs, the body, and the outside environment Consists of inspiration (inhalation) and expiration (exhalation) �Internal respiration Exchange of carbon dioxide and oxygen between the cells and the lymph surrounding them �Cellular respiration/oxidation Use of oxygen to release energy stored in nutrient molecules such as glucose This chemical reaction occurs within the cells

Respiration

Respiratory Organs and Structures �Nasal cavity Air enters nostrils or anterior nares, then the nasal cavity (separated by the nasal septum) lined with mucous membrane Three nasal conchae bones (turbinates) that increase the surface area of the nasal cavity Air moistened by mucous and warmed by blood vessels Cilia entrap particles and filter air �Pharynx Commonly known as throat; passageway for food and air 5 inches long and subdivided into nasopharynx (connected to eustachian tubes), oropharynx, and laryngopharynx Epiglottis is flap of cartilage lying behind the tongue and in front of entrance to larynx

Respiratory Organs and Structures � Larynx Aka voice box, a triangular chamber found below the pharynx Composed of 9 fibrocartilaginous plates, largest known as the Adam’s apple Characteristic vocal cords with space known as glottis � Trachea Aka windpipe, tubelike passageway extending from larynx and continues to form the two bronchi Composed of 15 to 20 C-shaped virtually non-collapsible rings of hyaline cartilage � Bronchi and Bronchioles Lower end of trachea separates into right and left bronchus (right bronchus is shorter, wider, and more vertical in position) As they enter the lung, they subdivide into smaller bronchioles (Y shaped in form)

Respiratory Organs and Structures �Alveoli Alveolar sacs consist of many alveoli Adult lung has about 500 million alveoli (3 x the amount necessary to sustain life) Inner surfaces covered with surfactant which helps stabilize the alveoli Through the moist walls of alveoli and capillaries is where rapid exchange of carbon dioxide and oxygen occurs �Lungs Separated by the mediastinum The apex is the top of each lung; broad lower part is the base which rests over the diaphragm Right lung has three lobes, left lung has two lobes

Respiratory Organs and Structures �Pleura A thin, moist, slippery membrane of tough endothelial cells that covers the lungs Each lung encased in double-walled sac (visceral and parietal pleura) Pleural fluid is located between the two membranes and prevents friction during each breath �Mediastinum AKA the interpleural space, located between the lungs Contains the thoracic viscera (thymus gland, heart, aorta, esophagus, trachea, thoracic duct, lymph nodes, and vessels)

Respiratory Organs and Structures

The Trachea

The Alveoli

The Lungs

The Breathing Process � Due to changes in pressure that occur within the chest cavity caused by cellular respiration and mechanical breathing movements � Inhalation/inspiration Diaphragm contracts and pulls downward, causing the thoracic cavity to expand � Exhalation/expiration Diaphragm relaxes and moves upwards, causing the thoracic cavity to become narrower � Respiratory movements and frequency of respiration Normal rate in quiet breathing for an adult male is about 14 to 20 breaths per minute (females are 16 to 20 breaths) Can be increased by muscular activity, increased body temperatures, emotions, and certain pathological disorders Can be decreased by sleeping and emotions

Control of Breathing �Neural factors Two neuronal pathways involved in breathing: phrenic nerves lead to diaphragm and intercostal muscle; the vagus nerve carries impulses to nose, larynx, lungs, skin, and abdominal organs �Chemical factors Level of carbon dioxide in the blood: as blood circulates through respiratory center, it senses increased carbon dioxide levels in blood and increases respiratory rate Chemoreceptors found in carotid arteries and aorta: if oxygen levels decline to low levels, impulses are sent which will stimulate the rate and depth of respiration

Lung Capacity and Volume �Spirometer: device that measures the volume and flow of air during inspiration and expiration �Tidal volume: amount of air that moves in and out of lungs with each breath (~500 m. L) �Inspiratory reserve volume (IRV): amount of air you can force a person to take in above the tidal volume (~2100 -3000 m. L) �Expiratory reserve volume (ERV): amount of air you can force a person to exhale above the tidal volume (~1000 m. L)

Changes in Respiration �Apnea: temporary stoppage of breathing movements �Dyspnea: difficult, labored, or painful breathing �Eupnea: normal or easy breathing �Hyperpnea: increase in depth and rate of breathing accompanied by abnormal exaggeration of respiratory movements

Changes in Respiration �Orthopnea: difficult or labored breathing when in a horizontal position �Tachypnea: abnormally rapid and shallow rate of breathing �Hyperventilation: condition that can be caused by disease or stress; rapid breathing causing the body to lose carbon dioxide too quickly leading to dizziness and possible fainting

Effects of Aging �Lung tissue loses elasticity �Rib cage becomes less flexible �Muscle strength decreases �Functioning alveoli decrease

Disorders of the Respiratory System - Infectious Causes �Common cold: hundreds of strains of the virus; runny nose, watery eyes, sneezing, stuffy head, and sore throat �Pharyngitis: bacterial or viral; painful swallowing and extreme dryness of throat �Laryngitis: secondary to other infections; hoarseness or loss of voice �Sinusitis: viral or bacterial; sinus pain and nasal discharge �Bronchitis: viral or bacterial; cough, fever, substernal pain, and rales/raspy sound

Disorders of the Respiratory System - Infectious Causes �Influenza (flu): viral infection; fever, mucous discharge, muscular pain, and extreme exhaustion �Pneumonia: viral or bacterial; chest pain, fever, chills, and dyspnea �Tuberculosis (TB): bacterial infection; cough, low-grade fever, weight loss, night sweats �Pertussis (whooping cough): bacterial infection; severe coughing attacks and dyspnea

Disorders of the Respiratory System - Noninfectious Causes �Rhinitis: inflammation of nasal mucous membranes causing swelling and increased secretions �Asthma: airways become obstructed due to an inflammatory response to a stimuli �Atelectasis: lungs fail to expand normally due to blockage of air passages �Pneumothorax: buildup of air within the pleural cavity on one side of the chest causing the lung to collapse

Disorders of the Respiratory System - Noninfectious Causes �Chronic obstructive pulmonary disease (COPD): group of lung diseases that limit air flow as a person exhales due to lung irritants and smoking �Cancer of the lung: most common cause of cancer death in the US �Pulmonary embolism: blood clot travels to the lungs after surgery or bed rest �Sudden infant death syndrome (SIDS): occurs in infants between 2 weeks to 1 year who stop breathing; exact causes unknown