CHAPTER VIII PDL 101 HUMAN ANATOMY & PHYSIOLOGY Ms. K. GOWRI. M.Pharm., Lecturer. Respiratory system Introduction: ‐ Cells of body need energy for activity to maintain homeostasis and this is obtained by oxygen. ‐ Releases oxygen ‐ The organs of respiratory system are 1. Nose 2. Pharynx 3. Larynx 4. Trachea 5. Two bronchi 6. Bronchioles 7. Two lungs and their coverings ‐ Intercostal muscles and diaphragm Æ respiration NOSE AND NASAL CAVITY: ‐ Position and structure ‐ Contains large irregular cavity divided into two equal passage by a septum. ‐ Hyaline cartilage ‐ Roof, floor, medial plane, lateral walls, posterior walls. ‐ Lining of nose – ciliated columnar epithelium consists goblet cells. ‐ Openings into the nasal cavity Æanterior nares, posterior nares, paranasal sinuses. ‐ Maxillary sinuses and frontal and sphenoidal, ethmoidal sinuses are present. Respiratory functions of nose: ‐ Air is warmed, moistened and filtered. ‐ Humidification. ‐ Olifactory function of nose. ‐ Olifactory nerves to brain Æ sensation of smell. Pharynx: ‐ Position – 12‐14cm long. ‐ 6th cervical vertebrae ‐ Structure – superiorly — inferior surface of skull. – inferiorly – continuous with the oesophagus. – anteriorly – the wall is incomplete because of nose, mouth and larynx. – posteriorly—areolar tissue, involuntary muscle. ‐ Nasopharynx Æ auditory tubes pharyngeal tonsils. ‐ Oropharynx Æ palatine tonsil, uvula. ‐ Laryngopharynx Æ 3rd to 6th cervical vertibrae. Structure: 1. Mucous memerane lining 2. Fibrous tissue 3. Muscle tissue ‐ Blood and nerve supply. Functions: ‐ Passage way for air and food ‐ Warming and humidifying ‐ Taste ‐ Hearing ‐ Protection ‐ Speech Larynx: ‐ Position – voice box. ‐ Structure – superior – hyoid bone and tongue – inferior – trachea – anterior – muscles of neck – posterior – 3rd and 6th cervical vertebrae – lateral – thyroid gland Structure: ‐ Cartilage – 1 thyroid cartilage – 1 cricoid cartilage } hyaline cartilage – 2 arthenoid cartilage – 1 epiglottis – elastic fibro cartilage ‐ Ligaments and memberanes are present ‐ Blood and nerve supply Æ parasympathetic nerve supply ‐ Cervical ganglia one on each side ‐ Laryngeal arteries ‐ Inferior of the larynx – vocal cords, relaxationÆ abduction AductedÆ stretching Functions: ‐ Production of sound – pitch, volume, resonance ‐ Speech ‐ Protection of the lower respiratory track ‐ Passage way for air ‐ Humidifying, filtering and warming Trachea: ‐ Position Æ 5th thoracic vertebrae ‐ Structures – superior – larynx – inferior – bronchi – anterior – isthmus, aorta – posterior – oesophagus . – lateral – lungs and lobes ‐ Contains 16‐20 C‐ shaped hyaline cartilages ‐ Three layers of tissue – outer layer – middle layer – inner layer Functions: ‐ Support and patency ‐ Mucociliary escalator ‐ Cough reflex ‐ Warming, humidifying and filtering of air Bronchi & smaller air passages: ‐ Right and left bronchi ‐ Bronchi, bronchioles ‐ Their structure Æ terminal bronchioles, respiratory bronchioles, alveolar ducts, alveoli. ‐ Nerve and blood supply, lymph drainage. ‐ Arterial blood supply – right and left bronchial arteries. ‐ Lymphatic vessels and lymphatic nodes ‐ Functions of air passage not involved in gaseous exchange: 1. Control of air entry. 2. Warming and humidifying. 3. Support and patency. 4. Removal of particulate matter. 5. Cough reflex. Functions of respiratory bronchioles & alveoli: 1. Defence against microbes 2. Warming &humidifying Lungs: ‐ The apex, base, costal surface & medial surface are present ‐ Two lungs, cone shaped ‐ Pulmonary artery & two veins draining out ‐ Space between in mediastinum Organization of the lung: ‐ Right lung – superior, middle & inferior ‐ Left lung – two lobes – superior inferior ‐ Pleura & pleural cavity ‐ Visceral pleura, parietal pleura, pleural cavity ‐ Inferior of the lung ‐ Pulmonary blood supply – pulmonary artery, deoxygenated blood ‐ Two pulmonary veins Respiration: ‐ Inflation &diflation of lungs occurring with each breath ensures that regular exchange of gasses takes place between the alveoli & external air. ‐ Diaphragm – dome shaped separating thoracic & abdominal cavities Muscles of respiration: ‐ Intercostal muscles ‐ External intercostal muscles ‐ Internal intercostal muscles cycle of respiration: ‐ Inspiration Æ active & energy is needed three respiratory pump ‐ Expiration – relaxation Æ passive ‐ Pause – next cycle begins Physiological variables affecting respiration: ‐ Elasticity ‐ Compliance ‐ Airflow resistance Lung volumes & capacities: ‐ 15 complete respiratory ctcles per minute ‐ Anatomical dead space 1. Tidal volume: about 500ml Æin & out 2. Inspiratory reserve volume – maximal inspiration 3. Inspiratory capacity – 500ml+ inspiratory reserve volume 4. Functional residual volume – amount remained after expiration 5. Expiratory reserve volume – largest volume of expiration 6. Residual volume – cannot be measured, remaining air 7. Vital capacity – max volume into & out Vc= tidal volume+IRV+ERV ‐ Alveolar ventilation= (TV‐anatomical dead space)xRR = (500‐150)ml x 15 per min = 5.25 litr/min ‐ Composition of air: ‐ Mixture of gasses like nitogen, oxygen, carbondioxide, water vapour & small quantities of inert gasses. ‐ Alveolar air & expired air ‐ Diffusion of gasses ‐ External respiration ‐ Internal respiration ‐ Transport of gases in blood stream Oxygen: ‐ Oxyhaemoglobin ‐ In solution in plasma water ‐ 2,3‐diphosphoglycerate Æ Co2 & head Æincreased release of O2 Co2: ‐ bicarbonate ions are formed in plasma. ‐ Dissolved in plasma. ‐ Carried in erythrocytes, carbaminohaemoglobin. Control of respiration: ‐ Respiratory centre ‐ Chemoreceptors Æ central chemoreceptor Æperipheral chemoreceptors Other factors influensing respiration are: 1. speech, singing 2. emotional displays, eg—crying, laughing, fear 3. drug – sedatives, alcohol 4. sleep Disorders of the upper respiratory tract: ‐ Infectious & inflammatory disorders ‐ Common cold & influenza ‐ Sinusitis, tonsillitis, pharyngitis ‐ Laryngitis & tracheitis ‐ Diphtheria ‐ Hay fever Æ childhood onset asthma Æ eczema in infants & young children Æ food allergies Tumours: ‐ Benign (haemangiomata) ‐ Carcinoma of the nose, sinuses, nasopharynx Disease of bronchi: ‐ Acute bronchitis ‐ Chronic bronchitis ‐ Asthma Æ cold air Æ cigarette smoking Æ air pollution Æ upper respiratory tract infection Æ emotional stress Æ strenuous exercise ‐ Bronchiectasis, emphysemia Æ pulmonary emphysemia ‐ Pneumonia – bronchopneumonia – lobularpneumonia ‐ Lung absess ‐ Tuberculosis Æ mycobacterium tuberculae Æ Pneumoconioses Æ due to industrial chemicals, silicosis, asbestos related diseases etc& ‐ Bronchial carcinoma, etc... ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐XXX‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ .