Respiratory system

Respiratory System

1. Respiratory System Dr . Mrs . Deepa K. Ingawale (Mandlik) Department of Pharmacology Poona College of Pharmacy, Pune

2. Learning Objectives To study the classification & functions of respiratory system. To describe the anatomy & physiology of nose, pharynx, larynx, trachea, bronchi and lungs. To describe the mechanism of external & internal respiration. To study the physiology of voice production. To describe the transports of oxygen & carbon dioxide. To explain the different lung volumes & capacities. To describe the various respiratory disorders.

3. Syllabus

4. Terminology Otorhinolaryngology : The branch of medicine that deals with the diagnosis & treatment of diseases of ears, nose & throat .

5. Respiration The exchange of gases between atmosphere, blood and cells is called as respiration. The process of respiration is divided into 3; Pulmonary ventilation: It is the inspiration (inflow) and expiration (outflow) of air between the atmosphere and lungs. External respiration: It is the exchange of gases between the lungs and the blood. Internal respiration: It is the exchange of gases between the blood and cells.

6. Organs of the Respiratory system Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Nose Pharynx Larynx Trachea Bronchi Lungs – alveoli Figure 13.1

7. 23- 7 Respiratory System Divisions Upper respiratory tract Nose Pharynx Lower respiratory tract Larynx Trachea Bronchi Lungs

8. Passageway for air Receptors for smell Filtration of incoming air to remove larger foreign material Moistens & warms the incoming air Upper Respiratory Tract Functions

9. Larynx : Helps in sound production Trachea: Passageway for air to & from lungs Bronchi: Transports air from trachea to lungs Lungs: T ransport air to alveoli for gas exchange Lower Respiratory Tract functions

10. Respiratory System Functions Gas exchange : Oxygen enters blood & carbon dioxide leaves the blood Regulation of blood pH : Altered by changing blood CO 2 levels by Carbonic acid Buffer system Sound production : Movement of air through vocal folds produces sound & speech Olfaction : Smell receptors are located into nose Thermoregulation : Heating and cooling of body Protection : Against m.o. by preventing entry & removing them

11. Nose (Nasal Cavity) External portion of respiratory system Opens through the nostrils Divided into left & right portion by a septum It is made of cartilage, bone, muscle & skin Nasal cavity is a hollow space lined by hairs & mucus membrane The nose is lined by ciliated columnar epithelium cells containing mucus secreting goblet cells

12. Functions of Nose Act as a passageway for air Moistens, warms & filters air Sense of smell: Olfactory receptors are located in the nose

13. Pharynx (Throat) It is funnel shaped tube of about 13 cm long. Common passage for digestive & respiratory systems Extends from internal nares to larynx Its wall is composed of skeletal muscles and lined with mucus membrane.

14. Division of Pharynx It is divided into 3 parts; Nasopharynx: The upper most part of pharynx, lies just posterior to nasal cavity. Oropharynx: The middle part of pharynx lies just posterior to oral cavity. Laryngopharynx: The lowest portion of pharynx lies just superior to larynx.  

15. Functions Passageway for air & food: Common organ involved in both respiratory & digestive system, air & food enters from nasal & oral section into pharynx Warming and humidifying the air: The air is further warmed & moistened as it passes through the pharynx. Taste: The olfactory receptors for taste are located in the pharynx. Protection: The lymphatic tissue (tonsils) produces antibodies in response to antigens. e. g microbes. Speech: It plays important role in speech by acting as a resonating chamber for sound.  

16. Larynx Also called as voice box. It is short passage that connects the pharynx with the trachea. The larynx is composed of irregular shaped cartilages. The main cartilages are 1 Thyroid cartilages 1 Cricoid cartilage Hyaline cartilage 2 Arytenoid cartilage 1 Epiglottis : Elastic cartilage

17. Structure of Larynx

18. Anterior view of Larynx

19. Posterior view of Larynx

20. Larynx Thyroid cartilage (Adam’s apple): It consists of two fused plates of hyaline cartilage that forms anterior wall of larynx gives its triangular shape. It is larger in males than in females. Cricoid cartilage: This lies below the thyroid cartilage. It is attached to the 1 st ring of trachea cartilage.

21. Larynx Arytenoid cartilage: These are made up of hyaline cartilage located posterior to thyroid cartilage. They provide attachment to the vocal cords. Epiglottis: It is a large leaf shaped piece of elastic cartilage . The stem of epiglottis is attached to thyroid cartilage but the leaf portion is unattached & free to open & close like a trap door.

22. Functions of larynx Production of sound: Responsible for production of sound. Protection of lower respiratory tract: During swallowing the larynx moves upward opens the pharynx & epiglottis closes the larynx. This ensures that food passes into the esophagus not into lower respiratory tract.

23. Functions of larynx Passageway for air: It acts as passageway for air. Humidifying, filtering & warming: It produces humidification, filtration & warming of air as it travels through the larynx.

24. Voice Production Vocal cords = two folds of mucus membrane with thyroid cartilage anteriorly & arytenoid cartilage posteriorly. When the muscles controlling vocal cords are relaxed the vocal cords open & passage way of air through larynx is clear, the vocal cords are called as abducted (open vocal cords). The pitch of sound produced by vibrating vocal cords is low . When the muscle controlling the vocal cords contracts, vocal cords are closed & the vocal cords are called as adducted (closed vocal cords).

25. Voice Production The pitch of sound produced by vocal cord is high . The pitch of voice is determined by tension applied to the vocal cords through appropriate set of muscles. Higher sound results by increasing the tension on the vocal cords. Lower sound results by decreasing the tension on the vocal cords.

26. Voice Production Inferior of the larynx viewed from above Inferior of the larynx viewed from above Inferior of the larynx viewed from above Abducted Vocal Cords Adducted vocal cords Abducted Vocal Cords Adducted vocal cords Adducted vocal cords Adducted vocal cords Adducted Vocal Cords

27. Trachea (Wind pipe) Tubular passageway for air. It is 12 cm long & 2.5 cm in diameter. It extends from larynx to 5 th thoracic vertebrae where it divides into left & right primary bronchi. It is located anterior to esophagus & has ‘C’ shaped cartilaginous rings within the wall. The trachea is made up of 4 layers. Adventitia Hyaline cartilage Sub mucosa Mucosa

28. Trachea (Wind pipe) The mucosa is made up of pseudo-stratified ciliated columnar epithelium containing ciliated columnar cells, goblet cells & basal cells. The cilia move in a single direction thereby keeping the tract dust free & particles. The single ‘C’ shaped cartilage rings provide a rigid support to tracheal wall. The point at which the trachea divides into right & left primary bronchi called as carina .

29. Trachea ‘C’ shaped cartilaginous rings of trachea Trachea and its associated structure

30. Functions of trachea Warming, humidifying & filtering: It produces humidification, filtration & warming of air as it travels through trachea. Support: ‘C’ shaped cartilage rings gives support to trachea. Mucociliary escalator: Mucus secreted by goblet cells moistens the air & traps the dust particles. Cough reflex: A nerve ending in trachea & bronchi are sensitive to irritation produces cough response.

31. Lungs Two lungs, lying on each side of the midline Cone shaped organs They are separated from each other by heart & present in the thoracic cavity. The lungs are divided into, Apex Base Coastal surface Medial surface

32. Lungs Apex: Narrow superior portion Base: Broad inferior portion Coastal surface: Surface of lung lying against the ribs Medial surface: It contains a region hilus through which bronchi, pulmonary blood vessels, lymphatic vessels & nerves enters & exit.

33. Structure of Lung

34. Pleura & Pleural Cavities The outer surface of each lung is covered by a serous membrane called as pleura . Pleura is divided into; Visceral pleura Parietal pleura The space between them is called as pleural cavity . The pleural membranes produce a pleural fluid that circulates in pleural cavity & acts as a lubricant, ensuring minimal friction of lung during breathing.

35. Lobes of lungs The right lung is subdivided into 3 lobes: Superior lobe Middle lobe Inferior lobe The left lung is subdivided into 2 lobes; Superior lobe Inferior lobe The right lung is thicker & broader than left lung.

36. Lobes of Lungs

37. Fissures of lung Right lung : It has two fissures Oblique fissure Horizontal fissure Left lung : It has one fissure Oblique fissure: It separates superior lobe & inferior lobe.

38. Fissures of lung

39. Bronchi At the carina point, the trachea divides into right pulmonary bronchus for right lung & left pulmonary bronchus for left lung. Right bronchus: It is wider & shorter than left bronchus. It is 2.5 cm long. After entering into right lung, primary bronchi is divided into 3 secondary bronchi , one for each lobe of lung. Left bronchus: It is 5 cm long & narrower than the right bronchus. After entering the left lung left primary bronchi is divided into 2 secondary bronchi , one for each lobe of lung.

40. Bronchi The secondary bronchi further divided into tertiary bronchi that divides into bronchioles . Bronchioles further divided into tube like structure called as terminal bronchioles . Terminal bronchioles are further divided into respiratory bronchioles .

41. Structure of Bronchi

42. Lobules Each lobe of lung is divided into many small compartments called as lobules . Each lobule contains lymphatic vessels, an arteriole, a venule & a branch from a terminal bronchiole. Terminal bronchioles are subdivided into small branches called as respiratory bronchioles . Respiratory bronchioles are subdivided into 2-11 alveolar ducts . The alveolar ducts are surrounded by alveoli & alveoli sacs . The alveoli are cup-shaped structure & surrounded by capillary network .

43. Lobules The alveolar wall consisting of 2 types of cells. Type 1 alveolar cells: It forms a lining of alveolar wall. Type 2 alveolar cells: It secretes alveolar fluid (mixture of phospholipids & lipoproteins), which keeps the alveolar cells moist. Alveolar duct and sac Alveolar duct and sac Alveolar duct and sac Alveolar duct and sac Alveolar duct and sac

44. Respiratory Tree Divisions Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

45. Bronchioles Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

46. Physiology of respiration Divided into 2 phases: External respiration Internal respiration

47. External respiration (Pulmonary gas exchange) It is the exchange of gases between the lungs & blood in pulmonary capillaries . It is the diffusion of O 2 from lung alveoli to blood in pulmonary capillaries & CO 2 in opposite direction. In this process, pulmonary capillary gains O 2 & loses CO 2 . Right ventricle: It pumps deoxygenated blood to lungs for purification. Left ventricle: It pumps oxygenated blood to all other parts of body.

48. External respiration (Pulmonary gas exchange) External respiration convert deoxygenated blood into oxygenated blood. O 2 diffuses from lungs alveoli into blood in pulmonary capillaries , where its partial pressure is 105 mm Hg, PCO 2 is 40 mm Hg in resting person.

49. External respiration (Pulmonary gas exchange) When the person doing exercise the PO 2 will be even lower because contracting muscle fibres are using more O 2 . Diffusion continues until the P O2 of pulmonary capillary blood increases to match the P O2 of alveolar air, 105 mm Hg. While O 2 is diffusing from alveolar air into deoxygenated blood, CO 2 is diffusing in opposite direction. The P CO2 of deoxygenated blood is 45 mm Hg in a resting person, whereas P CO2 , alveolar air is 40 mm Hg.

50. External respiration (Pulmonary gas exchange) Because of this difference in P CO2 , carbon dioxide diffuses from deoxygenated blood into the alveoli until the P CO2 of the blood decreases to 40 mm Hg. Thus the P O2 & P CO2 of oxygenated blood leaving the lungs are same as in alveolar air. The CO 2 that diffuses into the alveoli is eliminated from the lungs during expiration.

51. Internal respiration (Systemic gas exchange) The exchange of gases between the blood in systemic capillary & systemic tissue cells . In this process the systemic capillary gains CO 2 & loses O 2 . Internal respiration results in conversion of oxygenated blood to deoxygenated blood . Oxygenated blood entering the tissue capillaries has a P O2 of 100 mm Hg, whereas tissue cells have an average of P O2 of 40 mm Hg.

52. Because of this difference in P O2 , oxygen diffuses from the oxygenated blood through interstitial fluid & into tissue cells until the P O2 in the blood decreases to 40 mm Hg. This is average P O2 of deoxygenated blood entering tissue when you are at rest. While O 2 diffuses from the tissue blood capillaries into tissue cells, CO 2 diffuses in the opposite direction. Internal respiration (Systemic gas exchange)

53. Internal respiration (Systemic gas exchange) The average PCO 2 of tissue cells is 45 mm Hg whereas, tissue capillary oxygenated blood is 40 mm Hg. As a result CO 2 diffuses from tissue cells through interstitial fluid into the oxygenated blood until the PCO 2 in the blood increases to 45 mm Hg the PCO 2 tissue capillary deoxygenated blood. From here the deoxygenated blood returns to the heart and it is pumped to the lungs for another cycle of external respiration.

54. Transport of oxygen & carbon dioxide Transport of gases between the lungs & body tissues is a function of blood. Oxygen: O 2 does not dissolve easily in water; only about 1.5 % is dissolved in blood plasma. About 98.5 of O 2 is transported to Hb & combines with it inside RBCs. Each 100 ml of oxygenated blood contains about 20 ml of oxygen, 0.3 ml dissolved in plasma & 19.7 ml bound to haemoglobin.

55. Transport of O 2 & CO 2 O 2 & Hb combines in reversible reaction to form oxyhemoglobin as follows, 98.5% of O 2 is bound to haemoglobin & is trapped inside the RBCs, only dissolved O 2 (1.5%) can diffuses out of tissue capillaries into cells.   98.5% of the O 2 is bound to haemoglobin & is trapped inside the RBCs, only dissolved O 2 (1.5%) can diffuses out of tissue capillaries into cells.

56. Transport of O 2 & CO 2 Carbon dioxide: Each 100 ml of deoxygenated blood contains, 5 ml of CO 2 which is carried by blood in 3 main forms Dissolved CO 2 : 7% is dissolved in plasma. Carbaminohemoglobin: 23 % combines with Hb to form carbaminoglobin Bicarbonate ions: 70% is transported in plasma as bicarbonate ions

57. Pulmonary Volumes Tidal volume (TV) (500 ml): This is the amount of air passing in & out of lungs during each cycle of breathing (15 cycles/min) Inspiratory reserve volume (IRV) (3100 ml): This is the extra volume of air inhaled into lungs during maximal inspiration. i.e above normal TV. Expiratory reserve volume (ERV) (1200 ml): This is the extra volume of air expelled from the lungs during maximal expiration Residual volume (RV) (1200 ml): It is the volume of air remaining in the lungs after expiration.

58. Pulmonary Capacities Inspiratory capacity (IC) (3600 ml): It is the sum of Tidal volume + Inspiratory reserve volume. Functional residual capacity (FRC) (2400 ml): It is the sum of Residual volume + Expiratory reserve volume. Vital capacity (VC) (4800 ml): This is the maximum volume of air which can be moved in to & out of the lungs (Tidal volume + IRV+ ERV) Total lung capacity (6000 ml): It is the sum of all volume (TV + IRV + ERV + RV).

59. Spirogram

60. Disorders of respiratory system Pneumonia: It is an acute inflammation of the alveoli. Most common cause of pneumonia is the pneumococcal bacterium i.e. S treptococcus pneumoniae .   Tuberculosis: The bacterium M. tuberculosis an infectious communicable disease called as tuberculosis (TB) that most often affect the lungs & the pleura but may involve other parts of the body. Symptoms are fatigue, weight loss, lethargy, anorexia, low grade fever, night sweats, cough, dyspnoea, chest pain & hemolysis.

61. Disorders of respiratory system Coryza & influenza: A group of viruses called as rhinoviruses is responsible for about 40 % of all common cold. The symptoms are sneezing, excessive nasal secretion, dry cough & congestion, chills, fever (more than 39 o C), headache & muscular aches. Pulmonary edema: It is an abnormal accumulation of fluid in the interstitial spaces & alveoli of lungs. The symptoms are dyspnoea, wheezing, rapid breathing rate, restlessness, feeling of suffocation, cyanosis, paleness, excessive perspiration & pulmonary hypertension.

62. Disorders of respiratory system Cystic fibrosis (CF): It is an inherited disease of secretory epithelia that affects the airways, liver, pancreas, small intestine and sweat glands.   Asthma: It is characterised by chronic airway inflammation to variety of stimuli & airway obstruction. Symptoms include difficult breathing, coughing, wheezing, chest tightness, tachycardia, fatigue, moist skin and anxiety. Asbestos related disease: These are serious lung cancer disorders that develop after inhalation of asbestos particles. When they are inhaled they penetrate the lung tissue However, the fibres usually destroy the WBC’s and scarring of lung tissue.

63. Disorders of respiratory system Chronic obstructive pulmonary disease (COPD): It is characterised by chronic and recurrent obstruction of airflow which increases airway resistance. COPD are of 2 types Emphysema Chronic bronchitis Emphysema: It is characterised by destruction of alveoli walls producing abnormally large air spaces that remain filled with air during exhalation. It is cause by long term irritation, cigarette smoke; air pollution and occupational exposure to industrial dust are most common. Chronic bronchitis: It is characterised by excessive secretion of bronchial mucus. Cigarette smoking is the leading cause. Symptoms are productive cough (sputum), shortness of breath and wheezing.

64. Disorders of respiratory system Lung cancer: In the US lung cancer is the leading cause of death both in males & females. Cigarette smoking is the major cause. Symptoms are chronic cough, spitting blood from respiratory tract, wheezing, and shortness of breath, chest pain, and hoarseness, difficulty in swallowing weight loss, anorexia, fatigue, bone pain, confusing, headache, anaemia, jaundice and thrombocytopenia.