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The Respiratory System

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Presentation on theme: "The Respiratory System"— Presentation transcript:

1 The Respiratory System

2 Respiration – four distinct processes must happen
Pulmonary ventilation – moving air into and out of the lungs External respiration – gas exchange between the lungs and the blood Transport – transport of oxygen and carbon dioxide between the lungs and tissues Internal respiration – gas exchange between systemic blood vessels and tissues

3 Major Functions of the Respiratory System
Moving air to and from lungs Provide extensive area for gas exchange Protecting respiratory surfaces Produces sound Provide olfactory sensations

4 The Components of the Respiratory System

5 The nose and nasal cavity consists of:
External nares Nasal cavity Vestibule Superior, middle and inferior meatuses Hard and soft palates Internal nares Nasal mucosa

6 Function of the Nose The only externally visible part of the respiratory system that functions by: Providing an airway for respiration Moistening and warming the entering air Filtering inspired air and cleaning it of foreign matter Serving as a resonating chamber for speech Housing the olfactory receptors Sinuses in bones that surround the nasal cavity Sinuses lighten the skull and help to warm and moisten the air

7 Pharynx Funnel-shaped tube of skeletal muscle that connects to the: Nasal cavity and mouth superiorly Larynx and esophagus inferiorly It is divided into three regions Nasopharynx Oropharynx Laryngopharynx

8 Larynx (Voice Box) Attaches to the hyoid bone The three functions of the larynx are: To provide a patent airway To act as a switching mechanism to route air and food into the proper channels To function in voice production Epiglottis – elastic cartilage that covers the laryngeal inlet during swallowing

9 Movements of Vocal Cords

10 Trachea Flexible and mobile tube extending from the larynx into the mediastinum Composed of three layers Mucosa – made up of goblet cells and ciliated epithelium Submucosa – connective tissue deep to the mucosa Adventitia – outermost layer made of C-shaped rings of hyaline cartilage

11 The primary bronchi Trachea branches in the mediastinum into right and left bronchi Bronchi enter the lungs at the hilus Right bronchus is wider and steep compare to the left. Right has three and Left has two secondary bronchi

12 The bronchial tree System of tubes formed from the primary bronchi and their branches Primary bronchi branch into secondary Secondary bronchus goes to each lobe of the lungs Secondary bronchi branch into tertiary bronchi Tertiary bronchi

13 Lobes and surfaces of the lungs
Lobes of the lung are separated by fissures Right lung has three lobes Left lung has two lobes Concavity on medial surface = cardiac notch

14 The bronchioles Ultimately branch into terminal bronchioles
Delivers air to a single pulmonary lobule Terminal bronchiole becomes respiratory bronchioles Respiratory bronchioles end in ducts and sacs Respiratory exchange surfaces connected to circulatory system via pulmonary circuit

15 Gas Exchange Gas exchange occurs across
the respiratory membrane of the alveoli. The respiratory membrane is a composite structure consisting of three parts The squamous epithelial cells lining the alveolus The endothelial cells lining an adjacent capillary The fused basal laminae that lie between the alveolar and endothelial cells

16 Histology of Lungs Pneumocytes type I : squamous epithelial cells; sites for gas exchange Pneumocytes type II: also called septal cells. Produce surfactant, an oily secretion containing phospholipids and proteins; reduces the surface tension, keeps the alveoli open. Alveolar macrophage: also called dust cells; phagocytize any particles that have eluded other defenses.

17 Alveolar Surface Tension
Surface tension – the attraction of liquid molecules to one another at a liquid-gas interface The liquid coating the alveolar surface is always acting to reduce the alveoli to the smallest possible size Surfactant, a detergent-like complex, reduces surface tension and helps keep the alveoli from collapsing

18 Respiratory System Consists of the respiratory and conducting zones Respiratory zone Site of gas exchange Consists of bronchioles, alveolar ducts, and alveoli Conducting zone Provides rigid conduits for air to reach the sites of gas exchange Includes all other respiratory structures (e.g., nose, nasal cavity, pharynx, trachea etc.) Respiratory muscles – diaphragm and other muscles that promote ventilation

19 Dead Space Anatomical dead space – volume of the conducting respiratory passages (150 ml) Alveolar dead space – alveoli that cease to act in gas exchange due to collapse or obstruction Total dead space – sum of alveolar and anatomical dead spaces

20 Breathing Breathing, or pulmonary ventilation, consists of two phases Inspiration – air flows into the lungs Expiration – gases exit the lungs

21 Pulmonary Ventilation
Modes of Breathing Respiratory movements are classified By pattern of muscle activity Into quiet breathing and forced breathing

22 Pulmonary Ventilation
Quiet Breathing (Eupnea) Involves active inhalation and passive exhalation Diaphragmatic breathing or deep breathing Is dominated by diaphragm Costal breathing or shallow breathing Is dominated by ribcage movements

23 Pulmonary Ventilation
Forced Breathing Also called hyperpnea Involves active inhalation and exhalation Assisted by accessory muscles Maximum levels occur in exhaustion Other variations of breathing: Apnea—temporary cessation of breathing Dyspnea—labored, gasping breathing; shortness of breath

24 Respiratory Volumes Tidal volume (TV) – air that moves into or out of the lungs with each breath (approximately 500 ml) Inspiratory reserve volume (IRV) – air that can be inspired forcibly beyond the tidal volume (3000ml) Expiratory reserve volume (ERV) – air that can be evacuated from the lungs after a tidal expiration(1200 ml) Residual volume (RV) – air left in the lungs after strenuous expiration ( ml)

25 Respiratory Capacities
Inspiratory capacity (IC) – total amount of air that can be inspired after a tidal expiration (IRV + TV) Functional residual capacity (FRC) – amount of air remaining in the lungs after a tidal expiration (RV + ERV) Vital capacity (VC) – the total amount of exchangeable air (TV + IRV + ERV) Total lung capacity (TLC) – sum of all lung volumes (approximately 6000 ml in males)

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27 Alveolar Ventilation Physiologic (total) dead space
Sum of anatomic dead space and any pathological alveolar dead space A person inhales 500 mL of air, and 150 mL stays in anatomical dead space, then 350 mL reaches alveoli Alveolar ventilation rate (AVR) Air that ventilates alveoli (350 mL) X respiratory rate (12 bpm) = 4,200 mL/min. Of all the measurements, this one is most directly relevant to the body’s ability to get oxygen to the tissues and dispose of carbon dioxide

28 Pulmonary Ventilation
Pulmonary Volumes and Capacities.

29 Gas Exchange Composition of Air Nitrogen (N2) is about 78.6%
Oxygen (O2) is about 20.9% Water vapor (H2O) is about 0.5% Carbon dioxide (CO2) is about 0.04%

30 Composition of Air Dalton’s law—the total atmospheric pressure is the sum of the contributions of the individual gases Partial pressure: the separate contribution of each gas in a mixture At sea level 1 atm of pressure = 760 mm Hg Nitrogen constitutes 78.6% of the atmosphere, thus PN2 = 78.6% x 760 mm Hg = 597 mm Hg PO2 = 20.9% x 760 mm Hg = 159 mm Hg PH2O = 0.5% x 760 mm Hg = 3.7 mm Hg PCO2 = 0.04% x 760 mm Hg = 0.3 mm Hg PN2 + PO2 + PH2O + PCO2 = mmHg

31 Copyright 2009, John Wiley & Sons, Inc.

32 Gas Exchange An Overview of Respiratory Processes and Partial Pressures in Respiration.

33 Gas Exchange Figure 23–19b An Overview of Respiratory Processes and Partial Pressures in Respiration. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

34 Gas Transport Gas transport—the process of carrying gases from the alveoli to the systemic tissues and vice versa Oxygen transport 98.5% bound to hemoglobin 1.5% dissolved in plasma Carbon dioxide transport 70% as bicarbonate ion 23% bound to hemoglobin 7% dissolved in plasma

35 Oxygen Hemoglobin—molecule specialized in oxygen transport
Four protein (globin) portions Each with a heme group which binds one O2 to the ferrous ion (Fe2+) One hemoglobin molecule can carry up to 4 O2 Oxyhemoglobin (HbO2)—O2 bound to hemoglobin Deoxyhemoglobin (HHb)—hemoglobin with no O2 100% saturation Hb with 4 O2 molecules 50% saturation Hb with 2 O2 molecules

36 Copyright 2009, John Wiley & Sons, Inc.

37 Gas Transport Oxygen–Hemoglobin Saturation Curve
Is a graph relating the saturation of hemoglobin to partial pressure of oxygen Higher PO2 results in greater Hb saturation Is a curve rather than a straight line Because Hb changes shape each time a molecule of O2 is bound Each O2 bound makes next O2 binding easier Allows Hb to bind O2 when O2 levels are low

38 Gas Transport The Oxygen–Hemoglobin Saturation Curve
Is standardized for normal blood (pH 7.4, 37°C) When pH drops or temperature rises More oxygen is released Curve shifts to right When pH rises or temperature drops Less oxygen is released Curve shifts to left

39 Gas Transport An Oxygen—Hemoglobin Saturation Curve.

40 The Effects of pH and Temperature on Hemoglobin Saturation.
Gas Transport The Effects of pH and Temperature on Hemoglobin Saturation.

41 2,3-bisphosphoglycerate (BPG)
Gas Transport 2,3-bisphosphoglycerate (BPG) RBCs generate ATP by glycolysis Forming lactic acid and BPG BPG directly affects O2 binding and release More BPG, more oxygen released

42 Gas Transport Carbon Dioxide Transport in Blood.

43 Gas Transport A Summary of the Primary Gas Transport Mechanisms: Oxygen Transport.

44 Carbon Dioxide Relative amounts of CO2 exchange between the blood and alveolar air differs 70% of exchanged CO2 comes from carbonic acid 23% from carbamino compounds 7% dissolved in the plasma Blood gives up the dissolved CO2 gas and CO2 from the carbamino compounds more easily than CO2 in bicarbonate

45 Systemic Gas Exchange Systemic gas exchange—the unloading of O2 and loading of CO2 at the systemic capillaries CO2 loading CO2 diffuses into the blood Carbonic anhydrase in RBC catalyzes CO2 + H2O  H2CO3  HCO3− + H+ Chloride shift Keeps reaction proceeding, exchanges HCO3− for Cl− H+ binds to hemoglobin

46 Gas Transport A Summary of the Primary Gas Transport Mechanisms: Carbon Dioxide Transport.


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