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Respiratory System. Respiration Pulmonary ventilation (breathing): movement of air into and out of the lungs External respiration: O 2 and CO 2 exchange.

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Presentation on theme: "Respiratory System. Respiration Pulmonary ventilation (breathing): movement of air into and out of the lungs External respiration: O 2 and CO 2 exchange."— Presentation transcript:

1 Respiratory System

2 Respiration Pulmonary ventilation (breathing): movement of air into and out of the lungs External respiration: O 2 and CO 2 exchange between the lungs and the blood Transport: O 2 and CO 2 in the blood Internal respiration: O 2 and CO 2 exchange between systemic blood vessels and tissues Respiratory system Circulatory system

3 Respiratory System: Functional Anatomy Major organs – Nose, nasal cavity, and paranasal sinuses – Pharynx – Larynx – Trachea – Bronchi and their branches – Lungs and alveoli

4 Figure 22.1 Nasal cavity Nostril Oral cavity Pharynx Larynx Trachea Carina of trachea Left main (primary) bronchus Right main (primary) bronchus Right lung Left lung Diaphragm

5 Functional Anatomy Respiratory zone: site of gas exchange – Microscopic structures: respiratory bronchioles, alveolar ducts, and alveoli Conducting zone: passageway to gas exchange sites – Includes all other respiratory structures Respiratory muscles: diaphragm and other muscles that promote ventilation

6 Functions – Provides an airway for respiration – Moistens and warms the entering air – Filters and cleans inspired air – Serves as a resonating chamber for speech – Houses olfactory receptors Mucosa – Pseudostratified ciliated columnar epithelium – Cilia move contaminated mucus posteriorly to throat

7 Paranasal Sinuses In frontal, sphenoid, ethmoid, and maxillary bones Lighten the skull and help to warm and moisten the air

8 Figure 22.3b Nasopharynx Oropharynx Laryngopharynx (b) Regions of the pharynx Pharynx Muscular tube that connects to the – Nasal cavity and mouth superiorly – Larynx and esophagus inferiorly From the base of the skull to the level of the sixth cervical vertebra

9 Larynx Attaches to the hyoid bone and opens into the laryngopharynx Continuous with the trachea Functions 1.Provides an airway 2.Routes air and food into proper channels 3.Voice production Hyaline cartilage keeps larynx and trachea open Epiglottis: elastic cartilage; covers the larynx during swallowing

10 Figure 22.4b Epiglottis Body of hyoid bone Thyrohyoid membrane Vestibular fold (false vocal cord) Vocal fold (true vocal cord) Cricothyroid ligament Cricotracheal ligament Fatty pad Thyroid cartilage Cuneiform cartilage Corniculate cartilage Arytenoid cartilage Cricoid cartilage Tracheal cartilages Arytenoid muscles (b) Sagittal view; anterior surface to the right Thyrohyoid membrane

11 Figure 22.5 (a) Vocal folds in closed position; closed glottis (b) Vocal folds in open position; open glottis Base of tongue Epiglottis Vestibular fold (false vocal cord) Vocal fold (true vocal cord) Glottis Inner lining of trachea Cuneiform cartilage Corniculate cartilage

12 Voice Production Speech: intermittent release of expired air while opening and closing the glottis Pitch is determined by the length and tension of the vocal cords Loudness depends upon the force of air Chambers of pharynx, oral, nasal, and sinus cavities amplify and enhance sound quality Sound is “shaped” into language by muscles of the pharynx, tongue, soft palate, and lips

13 Trachea Windpipe Mucosa: ciliated pseudostratified epithelium with goblet cells Rings of Hyaline Cartilage

14 Figure 22.6a (a) Cross section of the trachea and esophagus Hyaline cartilage Submucosa Mucosa Seromucous gland in submucosa Posterior Lumen of trachea Anterior Esophagus Trachealis muscle Adventitia

15 Figure 22.7 Trachea Superior lobe of right lung Middle lobe of right lung Inferior lobe of right lung Superior lobe of left lung Left main (primary) bronchus Lobar (secondary) bronchus Segmental (tertiary) bronchus Inferior lobe of left lung Conducting Zone Structures Trachea  right and left main (primary) bronchi Each main bronchus enters one lung – Right main bronchus is wider, shorter, & more vertical than the left

16 Conducting Zone Structures From bronchi through bronchioles, structural changes occur – Cartilage rings give way to plates; cartilage is absent from bronchioles – Epithelium changes from pseudostratified columnar to cuboidal; cilia and goblet cells become sparse – Relative amount of smooth muscle increases

17 Respiratory Zone Respiratory bronchioles, alveolar ducts, alveolar sacs (clusters of alveoli) ~300 million alveoli account for most of the lungs’ volume and are the main site for gas exchange (a) Alveolar duct Alveoli Alveolar sac Respiratory bronchioles Terminal bronchiole

18 Three Types of Cells found in alveoli - Type I Cells – simple squamous cells; allow for gas diffusion - Surfactant Cell (Type II) – produce an oily secretion; it reduces surface tension so lungs don’t collapse - Alveolar Macrophages – Clear/swallow 2 million dust cells out of your lungs/hour. Type II Cell Macrophage

19 Figure 22.9c Capillary Type II (surfactant- secreting) cell Type I cell of alveolar wall Endothelial cell nucleus Macrophage Alveoli (gas-filled air spaces) Red blood cell in capillary Alveolar pores Capillary endothelium Fused basement membranes of the alveolar epithelium and the capillary endothelium Alveolar epithelium Respiratory membrane Red blood cell O2O2 Alveolus CO 2 Capillary Alveolus Nucleus of type I (squamous epithelial) cell (c) Detailed anatomy of the respiratory membrane

20 Figure Right superior lobe (3 segments) Right middle lobe (2 segments) Right inferior lobe (5 segments) Left superior lobe (4 segments) Left inferior lobe (5 segments) Right lungLeft lung

21 Blood Supply Pulmonary circulation (low pressure, high volume) – Pulmonary arteries deliver systemic venous blood Branch profusely, along with bronchi Feed into the pulmonary capillary networks – Pulmonary veins carry oxygenated blood from respiratory zones to the heart

22 Blood Supply Systemic circulation (high pressure, low volume) – Bronchial arteries provide oxygenated blood to lung tissue Arise from aorta and enter the lungs Supply all lung tissue except the alveoli – Pulmonary veins carry most venous blood back to the heart

23 Mechanics of Breathing Pulmonary ventilation consists of two phases 1.Inspiration: gases flow into the lungs 2.Expiration: gases exit the lungs Caused by changes between atmospheric gas pressure (14.7 psi) and gas pressure in the lungs

24 Figure Atmospheric pressure Intrapleural pressure 756 mm Hg (–4 mm Hg) Thoracic wall Diaphragm Lung Intrapulmonary pressure 760 mm Hg (0 mm Hg) Movement of air always flows from higher gas pressure to lower gas pressure

25 Pulmonary Ventilation Inspiration and expiration Mechanical processes that depend on volume changes in the thoracic cavity – Volume changes  pressure changes – Pressure changes  gases flow to equalize pressure

26 Boyle’s Law The relationship between the pressure and volume of a gas Used to explain the mechanics of breathing Under constant temperature, Pressure (P) varies inversely with volume (V): P 1 V 1 = P 2 V 2 P=1/V Lungs can change volume, so air pressure in lungs will also change

27 Inspiration An active process – Inspiratory muscles contract – Lungs are stretched and volume increases – Air pressure in lungs drops – Air flows into the lungs

28 Figure (1 of 2) Sequence of events Changes in anterior- posterior and superior- inferior dimensions Changes in lateral dimensions (superior view) Ribs are elevated and sternum flares as external intercostals contract. Diaphragm moves inferiorly during contraction. External intercostals contract. Inspiratory muscles contract (diaphragm descends; rib cage rises). 2 1 Thoracic cavity volume increases. 3 Lungs are stretched; intrapulmonary volume increases. 4 Intrapulmonary pressure drops. 5 Air (gases) flows into lungs down its pressure gradient until intrapulmonary pressure is 0 (equal to atmospheric pressure).

29 Expiration Quiet expiration is normally a passive process – Inspiratory muscles relax – Thoracic cavity volume decreases – Elastic lungs recoil and volume inside lungs decreases – Pressure inside lungs increases – Air flows out of the lungs Note: forced expiration is an active process: it uses abdominal and internal intercostal muscles

30 Figure (2 of 2) Sequence of events Changes in anterior- posterior and superior- inferior dimensions Changes in lateral dimensions (superior view) Ribs and sternum are depressed as external intercostals relax. External intercostals relax. Diaphragm moves superiorly as it relaxes. 1 Inspiratory muscles relax (diaphragm rises; rib cage descends due to recoil of costal cartilages). 2 Thoracic cavity volume decreases. 3 Elastic lungs recoil passively; intrapulmonary volume decreases. 4 Intrapulmonary pres- sure rises. 5 Air (gases) flows out of Lungs.

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32 Lung Volumes Tidal volume Inspiratory reserve volume Expiratory reserve volume Vital Capacity Residual Volume Total Lung Capacity

33 Tidal volume – normal breath in and out Vital Capacity – total amount of air you can forcefully inspire and expire in one respiratory cycle

34 Physical Factors Influencing Pulmonary Ventilation Inspiratory muscles consume energy to overcome three factors that hinder air passage and pulmonary ventilation 1.Airway resistance 2.Lung compliance 3.Lung Elasticity

35 Airway Resistance As airway resistance rises, breathing movements become more strenuous Severely constricting or obstruction of bronchioles – Can prevent life-sustaining ventilation – Can occur during acute asthma attacks and stop ventilation Epinephrine dilates bronchioles and reduces air resistance

36 Air Resistance Friction in the respiratory passageways, decreases the flow of gases. I.e. Asthma attack, constriction of bronchiole tubes Accumulation of mucus (infections) Cystic Fibrosis - mutation on chromosome #7 where lungs produce too much mucus – Leads to poor gas exchange since mucus blocks diffusion of gases.

37 Lung Compliance The ease at which lungs stretch Decrease in Lung compliance occurs when: – Smaller passageways are blocked Diminished by – Nonelastic scar tissue (fibrosis) – Reduced production of surfactant – Decreased flexibility of the thoracic cage Lung Elasticity The ability of the lung to recoil I.e. Emphysema Air sacs enlarge and lose their elasticity; lungs remain over inflated

38 Lung Elasticity The lungs’ ability to recoil I.e. Emphysema – Air sacs enlarge and lose their elasticity; lungs remain over inflated


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