Chapter 19 Respiratory System. Organs of the Respiratory System. Organs of the Respiratory System

Transcription

1 Chapter 19 Respiratory System Respiration is the process of exchanging gases between the atmosphere and body cells. Consists of the following events: ventilation external respiration transport internal respiration cellular respiration 1 Organs of the Respiratory System The respiratory system consists of the passages that filter incoming air and transport it to the many microscopic air sacs where gases are exchanged Role of the respiratory system is to provide oxygen for aerobic respiration and to eliminate carbon dioxide rapidly enough to maintain the ph of the internal environment 2 Organs of the Respiratory System 3 1

2 Upper Respiratory Tract 4 Upper Respiratory Tract Nose Nostrils (external nares) - openings to the respiratory system Has hairs to trap large particles Nasal cavity-hollow space behind the nose Nasal septum-divides the nasal cavity medially into right and left parts Nasal conchae-divide the nasal cavity into superior, middle and inferior meatuses 5 Mucous in Respiratory Tract Cilia move mucus and trapped particles from the nasal cavity to the pharynx 6 2

3 Sinuses Air-filled spaces in maxillary, frontal, ethmoid, and sphenoid bones that light the skull and act as resonating chambers 7 Pharynx Connect the nasal cavity with the larynx 8 Voice box Larynx 9 3

4 Vocal Cords Epiglottis-closes the larynx when a person swallows Glottis-opening to the larynx True vocal cords vibrate to produce sound Pitch is controlled by tension Intensity (loudness) is controlled by the force of air 10 Trachea Windpipe, flexible cylindrical tube 2.5 cm in diameter by 12.5 cm long Connects the larynx with the bronchi 11 Tracheostomy Performed to allow air to bypass an obstruction within the larynx 12 4

5 Bronchial Tree 13 Alveoli 300 million square meters of surface area Gas exchange occurs here 14 Diffusion Across Respiratory Membrane 15 5

6 Lungs Soft, spongy, coneshaped organ Lobes lobules Hilum-where bronchi and blood vessels enter and leave lungs Pleural cavity -space containing lungs Lined with the pleura(visceral, parietal) 16 Breathing Mechanism Breathing or ventilation is the movement of air from outside the body into the bronchial tree and alveoli air movements of inspiration and expiration changes in the size of the thoracic cavity due to changes in pressure 17 Inspiration Moving the plunger of a syringe causes air to move in or out Air movements in and out of the lungs occur in much the same way 18 6

7 Lungs at Rest When lungs are at rest, the pressure on the inside of the lungs is equal to the pressure on the outside of the thorax 19 Inspiration Intra-alveolar pressure decreases to about 758mm Hg as the thoracic cavity enlarges Atmospheric pressure forces air into the airways 20 Inspiration Shape of thorax at end of normal inspiration Shape of thorax at end of maximal inspiration aided by contraction of sternocleidomastoid and pectoralis minor muscles 21 7

8 Expiration due to elastic recoil of the lung tissues and abdominal organs 22 Maximal Expiration contraction of abdominal wall muscles contraction of posterior internal intercostal muscles 23 Respiratory Volumes and Capacities 24 8

9 Alveolar Ventilation minute ventilation tidal volume multiplied by breathing rate amount of air that is moved into the respiratory passageways alveolar ventilation rate major factor affecting concentrations of oxygen and carbon dioxide in the alveoli volume of air that reaches alveoli tidal volume minus physiologic dead space then multiplied by breathing rate 25 Nonrespiratory Air Movements 26 Alveoli gas exchanges between the air and blood occur within the alveoli alveolar pores allow air to pass from one alveolus to another 27 9

10 Respiratory Membrane consists of the walls of the alveolus and the capillary 28 Diffusion Through Respiratory Membrane Gases are exchanged between alveolar air and capillary blood because of differences in partial pressure 29 Oxygen Transport Most oxygen binds to hemoglobin to form oxyhemoglobin Oxyhemoglobin releases oxygen in the regions of body cells Much oxygen is still bound to hemoglobin in the venous blood 30 10

11 Carbon Dioxide Transport dissolved in plasma combined with hemoglobin in the form of bicarbonate ions 31 Life-Span Changes reflect accumulation of environmental influences reflect the effects of aging in other organ systems cilia less active mucous thickens swallowing, gagging, and coughing reflexes slow macrophages in lungs lose efficiency increased susceptibility to respiratory infections barrel chest may develop bronchial walls thin and collapse dead space increases 32 Clinical Application The Effects of Cigarette Smoking on the Respiratory System cilia disappear excess mucus produced lung congestion increases lung infections lining of bronchioles thicken bronchioles lose elasticity emphysema fifteen times more common lung cancer more common much damage repaired when smoking stops 33 11