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The Respiratory System Chapter 22. Figure 22.1 The Respiratory System Processes of Respiration: 1.Pulmonary Ventilation – movement of air into and out.

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Presentation on theme: "The Respiratory System Chapter 22. Figure 22.1 The Respiratory System Processes of Respiration: 1.Pulmonary Ventilation – movement of air into and out."— Presentation transcript:

1 The Respiratory System Chapter 22

2 Figure 22.1 The Respiratory System Processes of Respiration: 1.Pulmonary Ventilation – movement of air into and out of the lungs 2.External Respiration – gas exchange at the lungs; O 2 from lungs to blood, CO 2 from blood to lungs 3.Respiratory gas transport – use of blood to deliver O 2 to the tissues and deliver CO 2 to the lungs 4.Internal Respiration – gas exchange at the tissues; O 2 from blood to tissues, CO 2 from tissues to blood

3 Figure 22.1 The Respiratory System Anatomy of Respiration: Conducting zone – the group of respiratory passages that provide passage of air to the lungs. Includes nasal cavity, pharynx, larynx, trachea, bronchi, and bronchioles Respiratory zone – the microscopic lung structures where gas exchange occurs. Includes any structure with air sacs, called alveoli.

4 Figure 22.3b The Nasal Cavity Nasal Cavity - air passage that warms, moistens, and filters air, and also contains olfactory receptors. Medially divided by the nasal septum. External nares - the visible ‘nostrils’ that are the entrances into the nasal cavity Conchae - bony protrusions into the nasal cavity that cause the air to flow turbulently through the nasal cavity

5 Figure 22.3b The Nasal Cavity Respiratory mucosa – PSCCE with mucous and serous glands, producing a watery mucus rich in lysozymes, enzymes that break down bacteria Internal nares - the exits from the nasal cavity into the pharynx, located at the posterior side of the nasal cavity Paranasal sinuses - hollow spaces in the certain skull bones, lined with mucous membrane. This mucus drains into the nasal cavity Rhinitis – inflammation of the nasal mucosa Sinusitis – inflammation of the paranasal sinuses

6 Figure 22.3b The Pharynx The Pharynx - air and food passage that connects the nasal cavity and mouth to the larynx and esophagus. Commonly called the throat, divided into 3 regions: 1.Nasopharynx – posterior to nasal cavity, air only, lined with PSCCE 2.Oropharynx – posterior to oral cavity, air and food, lining is stratified squamous 3.Laryngopharynx – posterior to the epiglottis, air and food, lining is stratified squamous

7 Figure 22.4a, b The Larynx The Larynx - air passage that connects the pharynx to the trachea, composed of individual cartilages, mostly hyaline. Commonly called the voice box for its additional function of voice production Epiglottis - the only elastic cartilage, blocks entrance to the larynx during swallowing, ensuring food only enters the esophagus

8 Figure 22.5 Vocal Ligaments – elastic connective tissues in the lumen of the larynx. The glottis is the opening between these ligaments. Lining epithelium switches from stratified squamous to PSCCE below these ligaments. Vocal folds (true vocal cord) – vibrate to produce sound Vestibular folds (false vocal cords) - superior to vocal folds. Help close the glottis when swallowing Laryngitis – inflammation of the vocal ligaments The Larynx

9 Figure 22.6 The Trachea The Trachea - air passage from the larynx to the bronchi, commonly called the windpipe Trachealis muscle - smooth muscle on the posterior side of the trachea, used in coughing Trachea Layers in cross section: Mucosa – PSCCE with goblet cells. Cilia sweep debris toward throat for swallowing. Submucosa – connective tissue layer containing mucous glands Hyaline Cartilage – c-shaped to support air passage while also allowing esophagus expansion Adventitia - connective tissue to anchor trachea into surrounding tissues

10 Figure 22.7 The Bronchial Tree Bronchial Tree – the series of branching air passages leading to lung compartments Conducting zone structures: Primary bronchi – branch from trachea, one for each lung Secondary bronchi – branch from primary once inside the lung, one for each lung lobe Tertiary bronchi - branch from secondary Bronchioles – when the air passage diameter is <1mm Terminal bronchioles – when the diameter is <0.5mm

11 Figure 22.8 The Bronchial Tree Respiratory zone structures: Respiratory bronchioles – bronchioles with scattered alveoli Alveolar duct – blind- ended passage lined by alveoli Alveolar sac – a cluster of alveoli at the end of a duct Alveoli – the individual lung compartments where gas exchange with blood occurs

12 Figure 22.9a, b The Respiratory Membrane Respiratory Membrane – the fusion of alveolar and capillary walls, creating a 5µm thick membrane for gas exchange between air and blood

13 Figure 22.9c, d The Respiratory Membrane Type 1 cells – squamous cells of the alveolar wall, fuse to endothelial cells Type 2 cells - cuboidal cells that secrete surfactant, which reduces the surface tension of water to prevent alveolar collapse Alveolar macrophages - move amongst the respiratory membrane engulfing cells and debris Alveolar pores - small holes that connect adjacent alveoli

14 Figure 22.10a The Lungs Lungs - Paired organs that are highly compartmentalized into small air sacs Right Lung - divided into upper, middle, and lower lobes by the horizontal fissure and oblique fissure respectively Left Lung - divided into upper and lower lobes by the oblique fissure, also has the cardiac notch – an indentation for the heart’s apex

15 Figure 22.10c The Pleurae The Pleurae - a double layer of serous membrane producing serous fluid to reduce friction during lung ventilation/movement Visceral pleura - the serous membrane layer that clings to the lung surface Parietal pleura - the serous membrane that is separated from the lungs, clings to the internal surface of the thoracic body wall Pleural cavity - the space between the parietal and visceral layers, filled with serous fluid

16 Figure Mechanics of Breathing Pulmonary Ventilation - the movement of air into and out of the lungs based on the interactions of pressures in and around the body Inspiration - the movement of air into the lungs Expiration - the movement of air out of the lungs

17 Involved pressures: Atmospheric pressure (P atm )- pressure exerted by the air around the body, 760 mmHg Intrapulmonary pressure (P pul ) - the air pressure within the alveoli, rises and falls ( mmHg) but eventually equalizes with P atm Intrapleural pressure (P ip ) - the pressure in the pleural cavity (756 or -4 mmHg), 4 mmHg less than P pul (must be a negative pressure to prevent lung collapse) Transpulmonary pressure – the difference between intrapleural and intrapulmonary pressures, (P pul - P ip )… 760 – 756 = 4 mmHg Mechanics of Breathing

18 Figure Mechanics of Breathing Boyle’s law : P1V1 = P2V2 When the volume of a chamber increases, the pressure inside that chamber decreases. When the volume of a chamber decreases, the pressure inside that chamber increases

19 Figure 22.13a Mechanics of Breathing Inspiration: Contraction of diaphragm and external intercostal muscles increases the volume of the thoracic cavity and lungs Volume increase lowers the P pul to 759 mmHg (-1 mmHg) Air moves down its pressure gradient, into the lungs, until the P pul equalizes with the P atm

20 Figure 22.13b Mechanics of Breathing Expiration: Relaxation of the inspiratory muscles decreases volumes of thoracic cavity and lungs Volume decrease raises P pul to 761 mm Hg (+1 mmHg) Air moves down its pressure gradient, out of the lungs, until the P pul equalizes with the P atm again

21 Figure Mechanics of Breathing When P pul is less than the P atm, inspiration occurs and lung volume increases As the lung volume increases, so does pressure, eventually equalizing with P atm When P pul is greater than the P atm, expiration occurs and lung volume decreases As the lung volume decreases, so does pressure, eventually equalizing with P atm

22 Figure Factors Affecting Ventilation Airway Resistance – friction of air on walls of respiratory passages, is insignificant in a healthy person Alveolar surface tension – cohesion of water molecules would cause alveolar collapse. Surfactant from type 2 cells reduces this IRDS – infant respiratory distress syndrome – an inability to produce surfactant in premature births Lung compliance – the ability of the lungs to stretch as the thoracic cavity expands

23 Figure 22.16a Respiratory Volumes and Capacities Tidal volume - The volume of air ventilated during resting breathing (0.5 L) Inspiratory reserve volume - additional air that can be forcefully inhaled beyond tidal (2-3L) Expiratory reserve volume - additional air that can be forcefully exhaled beyond tidal ( mL) Residual volume - volume of air always in lungs, prevents lung collapse (1.2L)

24 Figure 22.16a Respiratory Volumes and Capacities Vital Capacity - total amount of exchangeable air ( L) Total Lung Capacity - total air volume in lungs (4.2-6 L) Dead spaces – areas where air is not involved in gas exchange Anatomical dead space – volume of conducting zone structures (150 mL) Alveolar dead space – volume of any nonfunctional alveoli

25 Measuring Ventilation Spirometry – the measurement of lung volumes and capacities Alveolar ventilation rate (AVR) - measure of air volume flowing into and out of alveoli AVR = Breath frequency x (Tidal volume – dead space) AVR = 12 breaths/min x (500mL – 150 mL) AVR = 4,200 mL/min

26 Properties of Gases Dalton’s Law - total pressure from a mixture of gases is the sum of the partial pressures of each individual gas; this partial pressure is proportional to the percentage of that gas in the mixture. Example: P atm = P O2 + P CO2 + P N2 Henry’s Law – when a mixture of gases is exposed to a liquid, the gases will dissolve in proportion to their partial pressures

27 Figure Gas Exchange External Respiration : The P O2 of the air in the alveoli is greater than the P O2 of the blood arriving at the alveoli Oxygen moves down its pressure gradient from the alveoli into the blood The P CO2 of the blood arriving at the alveoli is greater than the P CO2 of the air in the alveoli Carbon dioxide moves down its pressure gradient from the blood into the alveoli

28 Figure Gas Exchange Oxygen moves from the alveoli into the blood until the partial pressures equalize, taking about 0.25 sec

29 Figure Gas Exchange Ventilation–Perfusion coupling – Areas of lung tissue whose alveoli are well supplied with air experience dilation of local blood vessels Areas with relatively unventilated alveoli experience local vasoconstriction

30 Figure Gas Exchange Internal Respiration : The P O2 of the blood arriving at the tissues is greater than the P O2 of the tissues Oxygen moves down its pressure gradient from the blood into the tissues The P CO2 of the tissues is greater than the P CO2 of the blood arriving at the tissues Carbon dioxide moves down its pressure gradient from the tissues into the blood

31 Figure Oxygen Transport 1.5% of oxygen is transported by being dissolved in the blood’s plasma 98.5% of oxygen is transported by being bound to hemoglobin Hemoglobin is 100% saturated with oxygen upon leaving the lungs, and is still 75%saturated after delivering to the tissues Bohr effect – increased P CO2 weakens the bond between hemoglobin and oxygen Hypoxia – inadequate oxygen delivery to body tissues

32 Figure 22.22a Carbon Dioxide Transport 7-10% of carbon dioxide is transport by being dissolved in plasma 20% of carbon dioxide is transported by being bound to hemoglobin 70% of carbon dioxide is transported as bicarbonate ions (HCO 3 -) Dissolved carbon dioxide reacts with water to form carbonic acid (H 2 CO 3 ) which then dissociates into hydrogen ions (H+) and bicarbonate ions (HCO 3 -). Therefore, CO 2 levels in the blood affect blood pH by affecting H+ levels

33 Figure 22.22b Carbon Dioxide Transport Carbonic acid-bicarbonate ion buffer system – the chemical reaction involving carbon dioxide is reversible, allowing the prevention of drastic changes of blood pH Haldene effect - blood can transport more carbon dioxide when the P O2 is lower

34 Figure Control of Respiration Medullary Respiratory Centers – nuclei in the medulla that regulate breathing rate and depth Ventral respiratory group – generates the breathing rhythm, inspiratory nerves from here control the inspiratory muscles Dorsal Respiratory group – regulates the breathing rhythm with information from chemoreceptors in the blood Pontine respiratory group – regulates smooth transitions between inhalation and exhalation

35 Figure Control of Respiration Factors Affecting Breathing: Chemoreceptors – receptors for CO 2, O 2 and H+ in the medulla and major arteries. If carbon dioxide levels increase (decreasing pH), breathing rate and depth should increase Higher brain centers – emotions can affect breathing rate. The cerebral cortex allows us to voluntarily control breathing. Hyperpnea – increased breathing rate due to metabolic need, as in during exercise Other receptors – irritants or excessive stretch inhibits ventilation Hyperventilation – increased breathing rate beyond body needs. Leads to vasoconstriction of cerebral blood vessels and can lead to fainting

36 Figure Respiratory Disorders Chronic Obstructive Pulmonary Disorder (COPD) – any condition involving a decreased ability to expel air from the lungs. Symptoms include dyspnea (labored breathing), coughing, and hypoventilation Chronic bronchitis – excessive mucous production in the respiratory passages leading to frequent infections Emphysema – a progressive loss of the respiratory membrane and decreased lung elasticity Tuberculosis- bacterial infection spread through aerosols; treated with 1 year course of antibiotics Cystic fibrosis – genetic disease causing excessive, thick mucus production causing major infections


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