The Respiratory System MD 10.01 Describe the Structure of the Respiratory System MD 10.02 Analyze the Function of the Respiratory System
Respiratory System • Provides structures for exchange of O2 and CO2 in the body through respiration. • Includes the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli, lungs, pleura and mediastinum.
Respiratory System • Respiration subdivided into: • external respiration, internal respiration and cellular respiration. • Also responsible for the production of sound.
NASAL CAVITY • Air enters the respiratory system through theANTERIORNARES = nostrils • NASAL SEPTUM = divides nasal cavities into R and L sides • Turbinates are bones that protrude into the nasal cavity – they increase surface area for filtering dust and dirt particles by the mucous membrane.
NASAL CAVITY • Air is moistened by mucous membranes and warmed by blood vessels in the nasal cavity. • CILIA – the hairs in your nose, trap larger dirt particles
NASAL CAVITY • Nerve endings providing sense of smell are located in mucous membranes of the upper part of nasal cavity. • Olfactory
SINUSES • Cavities in the skull, ducts connect them to the nasal cavity, lined with mucous membrane to warm and moisten the air. Frontal Maxillary Ethmoid Sphenoid • Sinuses give resonance to the voice.
PHARYNX • The throat • Common passageway for air and food • 5” long • Divided into 3 sections • Nasopharynx (uppermost includes opening of eustachian tubes) • Oropharynx (middle section) • Laryngopharynx (Lower portion)
PHARYNX • When food is swallowed, the EPIGLOTTIS closes over the opening to the larynx, preventing food from entering the lungs.
LARYNX • Voice box • Triangular chamber below pharynx • Composed of 9 cartilaginous plates. • Within the larynx are vocal cords (GLOTTIS) • Lined with mucous membranes.
LARYNX • When air is expelled from the lungs, it passes the vocal cords, which sets off a vibration, creating sound. • The action of the tongue and lips on this sound produces speech.
TRACHEA • Windpipe • 4 ½ in. Long • Extends from larynx, passes in front of esophagus and continues to form the two bronchi.
TRACHEA • Walls are alternate bands of membrane and C-shaped rings of hyaline cartilage – this keeps trachea open • Can be obstructed by food, tumors or swelling of inflamed lymph nodes in the neck.
TRACHEA • Lined with ciliated mucous membrane. (function is to trap inhaled dust). • Cilia then sweep the dust-filled mucous to the pharynx. • Coughing and expectoration gets rid of dust-laden mucous
BRONCHI and BRONCHIOLES • Lower end of trachea divides into R and L bronchi • As they enter lungs, subdivide into bronchial tubes and bronchioles. The divisions are Y-shaped.
BRONCHI and BRONCHIOLES • Bronchi – similar to trachea with ciliated mucous membrane and hyaline cartilage • Bronchial tubes – cartilaginous plates (instead of C-shaped rings)
BRONCHI and BRONCHIOLES • Bronchioles – thinner walls of smooth muscle, lined with ciliated epithelium • At the end, alveolar duct and cluster of alveoli
ALVEOLI • 500 million in adults. 3X number needed to sustain life. • Arranged in clusters called alveolar sacs. Each alveolus has a globular shape. • Composed of a single layer of epithelial tissue
ALVEOLI • Inner surfaces covered with SURFACTANT – to keep alveoli from collapsing. • Each alveolus surrounded by capillaries. • O2 and CO2 exchange takes place between the alveoli and capillaries (DIFFUSION)
ALVEOLI • In capillaries • CO2 picked up throughout body diffuses from erythrocytes, through capillary walls, into alveoli and moves through respiratory structures and is exhaled. • O2 diffuses from air in alveoli into capillaries and then onto erythrocytes
LUNGS • Fill thoracic cavity • Separated by mediastinum and heart • Upper part = apex Lower part = base • Base fits snugly over diaphragm. Has concave shape.
LUNGS • Lung tissue porous and spongy – it floats due to alveoli and tremendous amount of air it contains. • R lung = larger and shorter (displaced by the liver) and has 3 lobes (superior, middle and inferior) • L lung smaller (displaced by the heart) and has 2 lobes (superior and inferior)
PLEURA • Thin, moist slippery membrane that covers lungs • Double-walled sac. 2 layers • Space is pleural cavity – filled with pleural fluid to prevent friction
MEDIASTINUM • Extends from sternum to vertebrae. • Interpleural space • Contains the Thymus gland, heart, aorta, pulmonary arteries and veins, superior and inferior vena cava, esophagus, trachea, thoracic duct, lymph nodes and vessels
FUNCTION OF THE RESPIRATORY SYSTEM • External respiration, internal respiration, and cellular respiration • Production of sound (vocal cords) • PULMONARY VENTILATION • (Breathing)
INSPIRATION • Intercostal muscles lift ribs outward • Sternum rises and the diaphragm contracts and moves downward • this increases the volume of the lungs, which lowers the pressure in the lungs making the pressure inside the lungs less than the outside pressure. • Air rushes in.
EXPIRATION • Opposite action takes place. • Contracted intercostals and diaphragm relax. • Causing the space within the thoracic cavity to decrease thus causing the internal pressure to increase. • Increased pressure forces air from the lungs. • Exhalation is a passive process
RESPIRATORY MOVEMENTS • 1 inspiration + 1 expiration = 1 respiration • Normal adult = 14 - 20 respirations per minute • Increases with exercise, body temperature, certain diseases. • Changes with Age - newborn = 40-60/min • Sleep = respirations • Emotion can or rate
RESPIRATORY MOVEMENTS • Coughing • Deep breath followed by forceful expulsion of air • To clear lower respiratory tract.
RESPIRATORY MOVEMENTS • Hiccups • spasm of the diaphragm and spasmodic closure of the glottis • Irritation to diaphragm or phrenic nerve
RESPIRATORY MOVEMENTS • Sneezing • Air forced through nose • To clear respiratory tract
RESPIRATORY MOVEMENTS • Yawning • Deep prolonged breath that fills the lungs • Increases oxygen within the blood. • Believed to be caused by need to increase O2 level in the blood.
CONTROL OF BREATHING • Breathing controlled by neural and chemical factors
NEURAL FACTORS • Respiratory center located in MEDULLA OBLONGATA • on CO2 or O2 in the blood will trigger respiratory center
NEURAL FACTORS • PHRENIC NERVE • motor nerve stimulating the diaphragm • VAGUS NERVE • sensory nerve carrying impulses from the nose, larynx, lungs, skin and abdominal organs.
NEURAL FACTORS • Rhythm of breathing can be changed by stimuli originating within body’s surface membranes. • Ex. A sudden drenching with cold water makes us gasp, irritation to nose or larynx makes us sneeze or cough.
NEURAL FACTORS • Respiratory center can be affected by drugs such as depressants, barbiturates or morphine.
CHEMICAL FACTORS • Depends on the levels of CO2 in the blood (respiratory center in brain) • Chemoreceptors in aorta and carotid arteries sensitive to the amount of blood O2
LUNG CAPACITY AND VOLUME • SPIROMETER – device that measures lung capacity • TIDAL VOLUME – amount of air that moves in and out of lungs with each breath. Normal = 500 ml • RESIDUAL VOLUME – amount of air left in lungs that cannot be voluntarily expelled. Allows for constant gas exchange between breaths.
TYPES OF RESPIRATION • APNEA – no breathing • DYSPNEA – difficult, labored or painful breathing • ORTHOPNEA – difficult breathing when body is in horizontal position • TACHYPNEA – rapid and shallow breathing
HYPERVENTILATION • Can be caused by disease or stress. • Rapid breathing causes body to lose CO2 too quickly, blood CO2 decreases which leads to alkalosis
HYPERVENTILATION • Symptoms: dizziness and possible fainting • Rx: have person breathe into a paper bag (Air in bag contains increasing amounts of CO2, which raises the blood level of CO2 to normal levels
The Respiratory System MD 10.03 Disorders of the Respiratory System
PLEURISY • Inflammation of the lining of the lungs • Usually occurs in conjunction with pneumonia and other lung infections • Symptoms – sharp, stabbing pain when breathing, dyspnea and fever