The respiration and the respiratory system- lecutre PDF

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the respiration and the respiratory system The Respiratory System  process of gas exchange  muscles involved in inhalation & exhalation  mechanisms involved in the control of breathing Respiratory Diseases  Asthma  Chronic Obstructive Pulmonary Disease  Rhinitis  Colds & Influenza  Pneumonia

Why do we need to breathe? Aerobic respiration Glucose + Oxygen = Water + CO2 + ATP  Adenosine triphosphate (ATP)  energy for cellular function  Get rid of carbon dioxide

Primary function of respiratory system  Uptake of O2 & elimination of CO2 Designed for gas exchange Works in conjunction with CV system – transport gases in blood Failure of either system – rapid cell death from O2 starvation

Organisation of the Respiratory System Upper Respiratory Tract:



Nose & pharynx

Lower Respiratory Tract: 

Larynx, trachea, bronchi & lungs

Functional classification: Conducting portion System of interconnecting tubes from nose to terminal bronchioles Respiratory portion Area of gas exchange from respiratory bronchioles to alveoli

External Nasal Structures  Nasal bones & cartilage lined with mucous membrane  Openings called external nares or nostrils

 Olfactory epithelium for sense of smell  Pseudostratified ciliated columnar with goblet cells lines nasal cavity  warms air due to high vascularity  mucous moistens air & traps dust  cilia move mucous towards pharynx  Paranasal sinuses open into nasal cavity lighten skull & resonate voice Trachea & Bronchial Tree  Primary bronchi supply each lung  Secondary bronchi supply each lobe of the lungs (3 right & 2 left)

 Tertiary bronchi supply each bronchopulmonary segment  Further branchings called bronchioles form a bronchial tree

Pleural Membranes & Pleural Cavity  Visceral pleura covers lungs  Parietal pleura lines ribcage & covers upper surface of diaphragm  Pleural cavity is potential space between ribs & lungs Structure of a Lobule Respiratory bronchiole Alveolar ducts surrounded by alveolar sacs & alveoli Aveoli Cup-shaped

Approx. 300 million  large surface area Function = gas exchange

Alveolar sacs

Large surface area Thin walls

HELP

DIFFUSION

Moist lining Copious blood supply

 Type I alveolar cells  simple squamous cells where gas exchange occurs  Type II alveolar cells (septal cells)

 secrete alveolar fluid containing surfactant  Alveolar dust cells/Macrophage cells wandering macrophages remove debris Alveolar-Capillary Membrane  Respiratory membrane = 0.5 micron thick  Exchange of gas from alveoli to blood  4 Layers of membrane to cross  alveolar epithelial wall of type I cells  alveolar epithelial basement membrane  capillary basement membrane  endothelial cells of capillary  Vast surface area = handball court Control of Respiration The Respiratory Centre  Respiration rhythm controlled & coordinated  Respiratory muscles controlled by neurons in pons & medulla Pulmonary Ventilation  Air will always flow from High to Low pressure  Air moves into lungs when pressure inside lungs is less that atmospheric pressure  Air moves out of lungs when pressure inside lungs is greater than atmospheric pressure

 Breathing in requires muscular activity & chest size changes  Contraction of the diaphragm flattens the dome and increases the vertical dimension of the chest Quiet Inspiration (inhalation)  Diaphragm moves 1 cm & ribs lifted by muscles  Intrathoracic pressure falls and 2-3 liters inhaled (exhalation)  Passive process with no muscle action  Elastic recoil & surface tension in alveoli pulls inward

Alveolar pressure increases & air is pushed out Labored Breathing (forced breathing)  Forced expiration  abdominal muscle force diaphragm up  internal intercostals depress ribs  Forced inspiration  sternocleidomastoid, scalenes & pectoralis minor lift chest upwards as you gasp for air  Coughing  Deep inspiration, closure of rima glottidis (space between the vocal cords and larynx) & strong expiration blasts air out to clear respiratory passages  Sneezing  Exhalation muscles spasmodically contract forcefully expelling air through the nose & mouth  Hiccuping  Spasmodic contraction of diaphragm & quick closure of rima glottidis produce sharp inspiratory sound. Usually caused by irritation of sensory nerve endings Limbic system  Anticipation of activity = activation of limbic system  Leads to increased rate & depth of respiration Proprioceptor simulation  Receptors monitor movement  Rapidly increase breathing rate & depth Temperature  Heat leads to increased rate & depth of respiration  Sudden cold leads to cease in respiration (Apnea) Pain  Sudden, severe pain leads to Apnea  Prolonged pain leads to increased rate of respiration  Parasympathetic Innervation

 supplied by vagus nerves which release Acetylcholine  couples with muscarinic receptors; human lung has M1, M2 & M3 receptors  M3 present on airway smooth muscle & submucosal glands . Stimulation causes  bronchoconstriction secretion from submucosal mucous glands

 2 systems of blood flow to lungs :  Pulmonary Circulation  receives blood from the right heart & is critical for gaseous exchange  Bronchial Circulation  Arterial supply perfuses lung tissue to supply nutrients & remove metabolic by products

Glands  Mucus Secretion  Inhibited by the sympathetic system  Stimulated by parasympathetic system, inflammatory mediators, chemicals (e.g. air pollutants) & physical (e.g. cold air) stimuli  Excess mucus narrows airways & causes resistance

Airway resisyance  Resistance to airflow depends upon airway size  Smaller airway  more resistance  Increase size of chest  airways increase diameter  Contract airway smooth muscle  decreases airway diameter  Asthma/Bronchitis

Asthma

 Asthma affects 5-10% Population  Reversible increases in airway resistance  involves bronchoconstriction & inflammation  excess mucus secretion  Asthma Attack  Difficulty breathing out, wheezing & cough  Tight chest  Symptoms often worse at night and during exercise Acute severe asthma (Status Asthmaticus)

Stimul us Mast Cell/Mononuclear Cell

Spasmog ens

Chemota xins

Bronchospa sm

Late Phase: Inflammati on

Phases of Asthma attack Immediate Phase  Release of Spasmogens  Histamine  Leukotrienes LTC4 & LTD4

 Platelet-activating factor (PAF) from mast cells & mononuclear cells  Bronchospasm

Late Phase  Chemotaxins (including LTB4 & PAF) attract leukocytes, especially eosinophils & mononuclear cells  Inflammation  Airway hyperactivity  3-6 hours after initial phase Bronchodilators  1. β2- Adrenoreceptor Agonists 

Salbutamol & Terbutaline



Salmeterol & Formoterol

 2. Muscarinic Receptor Antagonists 

Ipratropium Bromide, Oxitropium,



Tiotropium Bromide

 3. Xanthines 

Theophylline & Aminophylline

Anti-Inflammatory Agents Glucocorticosteroids  Beclometasone diproprionate, Budesonide & Fluticasone proprionate (Inhaled)  Prednisolone (Oral)  Hydrocortisone (Intravenous Injection)  Ineffective for relief of immediate phase  Reduce inflammation in delayed phase

COPD chronic obstructive pulmonary disease  Characterized by airflow obstruction that is partially reversible & progressively deteriorates

 Reduced lung function  as expressed by Forced Expiratory Volume in 1 second (FEV1)  Exacerbation of symptoms  including cough & mucus secretion  Reduced capacity to undertake physical exertion & have poor Quality of Life Treatments  . β2 - Adrenoceptor Agonists  2. Anticholinergics  3. Corticosteroids 4. Oxygen

Rhinitis  Common & debilitating disease characterised by : Rhinorrhoea, sneezing, itching & nasal congestion  Allergic Rhinitis (Hay Fever)  response to exposure to allergen e.g. pollen  allergen binds to cell surface of mast cells & triggers the release of inflammatory mediators e.g. histamine  Non-allergic Rhinitis  triggered by viral infection, hormone imbalance or occupational exposure to chemicals or drugs management  . Antihistamines  2. Glucocorticoids

Colds Rhino or adenovirus Influenza Upper respiratory tract infection Influenza virus A, B and C

Pneumonia Infection of alveoli...