Week 11 Respiratory system.pdf

The Respiratory System H.C. Adhihetty Visiting lecturer FUNCTION OF RESPIRATORY SYSTEM 2 ORGANS OF THE RESPIRATORY SYSTEM 3  The respiratory system is divided into two parts: upper respiratory tract...

The Respiratory System H.C. Adhihetty Visiting lecturer FUNCTION OF RESPIRATORY SYSTEM 2 ORGANS OF THE RESPIRATORY SYSTEM 3  The respiratory system is divided into two parts: upper respiratory tract lower respiratory tract Upper respiratory tract includes- ??? Lower respiratory tract includes-??? 4 The Nose 5 Anatomy of the nasal cavity Olfactory receptors are located in the mucosa on the superior surface The rest of the cavity is lined with respiratory mucosa  Moistens air  Traps incoming foreign particles 6  Lateral walls have projections called conchae  Increases surface area  Increases air turbulence within the nasal cavity The nasal cavity is separated from the oral cavity by the palate  Anterior hard palate (bone)  Posterior soft palate (muscle) 7 Paranasal sinuses Cavities within bones surrounding the nasal cavity Frontal bone Sphenoid bone Ethmoid bone Maxillary bone Function of the sinuses Lighten the skull Act as resonance chambers for speech Produce mucus that drains into the nasal cavity 8 Pharynx (Throat) 9 10 Larynx (Voice Box) Epiglottis Superior opening of the larynx Routes food to the larynx and air toward the trachea 11 Trachea (Windpipe) Connects larynx with bronchi Lined with ciliated mucosa Beat continuously in the opposite direction of incoming air Expel mucus loaded with dust and other debris away from lungs Walls are reinforced with C shaped hyaline cartilage  The trachea & bronchi are reinforced with C-shaped rings of cartilage (these prevent the tubes collapsing during inhalation) 12 Video clip- mucociliary action 13 Lungs Occupy most of the thoracic cavity Apex is near the clavicle (superior portion) Base rests on the diaphragm (inferior portion) Each lung is divided into lobes by fissures  Left lung –two lobes  Right lung –three lobes Covering of the lungs Pulmonary (visceral) pleura covers the lung surface Parietal pleura lines the walls of the thoracic cavity Pleural fluid fills the area between layers of pleura to allow gliding 14 15 Respiratory Tree Divisions Primary bronchi Secondary bronchi Tertiary bronchi Bronchioli Terminal bronchioli 16 17  Primary Bronchi Formed by division of the trachea Enters the lung at the hilus Right bronchus is wider, shorter, and straighter than left Bronchi subdivide into smaller and smaller branches Bronchi contain cartilage and a ciliated mucous membrane Bronchioles Smallest branches of the bronchi All but the smallest branches have reinforcing cartilage No mucous membrane Terminal bronchioles end in alveoli 18 Bronchioles 19 Respiratory Zone  The region where the actual gas exchange occurs.  Structures  Respiratory bronchioli  Alveolar duct  Alveoli  Function of the respiratory zone To ensure oxygen enters the bloodstream and carbon dioxide is removed. 20 Alveoli  Structure of alveoli  Alveolar duct  Alveolar sac  Alveolus  Gas exchange takes place within the alveoli in the respiratory membrane Respiratory membrane (Air blood barrier)  Thin squamous epithelial layer lining alveolar walls  Pulmonary capillaries cover external surfaces of alveoli 21 Respiratory membrane 22 Events of Respiration Respiration is divided into several stages: 1. Pulmonary ventilation –moving air in and out of the lungs 2. External respiration –gas exchange between pulmonary blood and alveoli 3. Transport of Gases- O₂ is transported from the lungs to tissues, and CO₂ from the tissues to the lungs via the bloodstream. 4. Internal Respiration- The exchange of gases between the blood and the body tissues. 23 MECHANISMS OF BREATHING (PULMONARY VENTILATION) Two phases Inspiration –flow of air into lung Expiration –air leaving lung Inspiration The diaphragm contracts and flattens, increasing the size of the thoracic cavity. The external intercostal muscles contract, expanding the rib cage. External air is pulled into the lungs due to an increase in intrapulmonary volume 24 Expiration The diaphragm relaxes and moves upward, reducing the size of the thoracic cavity. The intercostal muscles relax, allowing the rib cage to return to its original position. This compresses the lungs, increasing pressure, and forcing air out. 25 26 27 Pressure difference in the Thoracic cavity Normal pressure within the pleural space is always negative (intrapleural pressure) Differences in lung and pleural space pressures keep lungs from collapsing GAS EXCHANGE Gas crosses the respiratory membrane by diffusion  Oxygen enters the blood  Carbon dioxide enters the alveoli Macrophages add protection Surfactant coats gas-exposed alveolar surfaces 28 EXTERNAL AND INTERNAL RESPIRATION  External respiration is the movement of O₂ and CO₂ between the lungs and the bloodstream.  Internal respiration is the exchange of O₂ and CO₂ between the blood and the tissues 29 External respiration Oxygen movement into the blood  The alveoli always has more O₂ than the blood  O₂ moves by diffusion towards the area of lower concentration  Pulmonary capillary blood gains O₂ Carbon dioxide movement out of the blood Blood returning from tissues has higher concentrations of CO₂ than air in the alveoli Pulmonary capillary blood gives up CO₂ Blood leaving the lungs is oxygen-rich and carbon dioxide-poor 30 External respiration 31 Gas transport in the blood Oxygen transport in the blood  Inside red blood cells attached to hemoglobin (oxyhemoglobin [HbO2])  A small amount is carried dissolved in the plasma 32  Carbon dioxide transport in the blood  Most is transported in the plasma as bicarbonate ion (HCO3– )  A small amount is carried inside red blood cells on hemoglobin, but at different binding sites than those of oxygen 33 Internal respiration Exchange of gases between blood and body cells An opposite reaction to what occurs in the lungs  Carbon dioxide diffuses out of tissue to blood  Oxygen diffuses from blood into tissue 34 Time to test your knowledge!!!! 1. Identify the organs of the upper respiratory tract, and state their functions. 2. List the organs of the lower respiratory tract. Which organs are involved only in conduction? 3. Where does gas exchange take place? 4. How does the respiratory system protect itself from potentially harmful substances in the air? 5. What is the significance of the C-shaped cartilage in the trachea? 6. What is the role of surfactant in the alveoli? 7. Define the following terms: a) Pulmonary ventilation b) External respiration c) Internal respiration 35 36