Module 12 - Respiratory System PDF

18/11/2024 Because learning changes everything.® RESPIRATORY Because SYSTEM learning changes every...

18/11/2024 Because learning changes everything.® RESPIRATORY Because SYSTEM learning changes everything. ® Anatomy of Respiratory System Functions of the Respiratory System Structures and Histology of Respiratory Tract Upper respiratory tract – nose and nasal cavity, pharynx, larynx Lower respiratory tract – trachea, bronchi, tracheobronchial tree, alveoli, lungs, pleura Behavior of Gases Behavior of gases and ventilation Measurement of lung function Behavior of gases and respiration Physiology of the Respiratory System Factors affecting alveolar ventilation Factors affecting diffusion through the respiratory membrane Oxygen and Carbon Dioxide Transport in the Blood Hemoglobin Transport of O2 Transport of CO2 Physiological factors affecting gas transport Regulation of Ventilation Respiratory areas in the brainstem Generation of rhythmic ventilation 1 2 Chapter Opener Because learning changes everything.® Because learning changes everything.® ANATOMY OF THE RESPIRATORY SYSTEM Respiration occurs at multiple levels We respire when our blood travels thru consists of the structures used to acquire O2 and remove our lungs and picks up O2 and drops off CO2 from the blood CO2 We also respire when that O2 gets all cells in the body require O2 to synthesize the chemical delivered to our cells and CO2 is carried energy molecule, ATP away from those cell We respire when our cells use that O2 to CO2 is a by-product of ATP production and must be make needed energy removed from the blood and create CO2 as waste All levels of respiration increased levels of CO2 will lower the pH of the blood are essential for life. 4 Because learning changes everything.® Because learning changes everything.® 1. External nose – encloses the chamber for air inspiration. Respiratory System. 2. Nasal cavity - warms, humidifies, and cleans for inspired air The upper respiratory 3. Pharynx – or throat; shared passageway tract consists of the for food and air external nose, nasal 4. Larynx - or voice box; rigid structure cavity, pharynx (throat), helps keep the airway constantly open and the larynx. 5. Trachea – or windpipe; serves as an air- cleaning tube to funnel inspired air to each lung The lower respiratory 6. Bronchi – tubes that direct air into the tract consists of the lungs trachea, bronchi, and 7. Lungs – a labyrinth of air tubes and a lungs. complex network of air sacs, called alveoli, and capillaries; each air sac is the site of gas exchange between the air and blood 5 6 1  18/11/2024 FUNCTIONS OF THE RESPIRATORY SYSTEM Because learning changes everything. ® Because learning changes everything.® Respiration Four simultaneous processes occur during gas exchange between air and blood or breathing Two aspects – ventilation and respiration (1) Pulmonary ventilation or breathing - movement of Ventilation - movement of air into and out of the lungs air into and out of the lungs; Respiration – diffusion of gases across cell membranes (1) External Respiration - exchange of O2 and CO2 between (2) Pulmonary gas exchange - exchange of O2 and the air in the lungs and the blood CO2 between the air in the lungs and the (2) Internal Respiration - exchange of O2 and CO2 between blood; the blood and the tissues Ventilation and respiration occur in different regions of the (3) Gas Transport - O2 and CO2 travel in the blood to and respiratory tract from cells; and Conducting zone – from nose to smallest air tubes within the lungs; strictly for ventilation (4) Tissue gas exchange - exchange of O2 and CO2 Respiratory zone – lungs and specialized small air tubes between the blood and the tissues and alveoli; gas exchange 7 8 Because learning changes everything.® STRUCTURES and HISTOLOGY Because learning of theeverything. changes ® Other Functions of Respiratory System: RESPIRATORY TRACT 1. Regulation of blood pH. The respiratory system can alter blood UPPER RESPIRATORY TRACT: pH by changing blood CO2 levels. 2. Production of chemical mediators. Lungs produce ACE Nose and Nasal Cavity (angiotensin-converting enzyme), a component of blood consists of the external nose and pressure regulation the nasal cavity external nose is the visible 3. Voice production. Air movement past the vocal cords makes structure that forms a sound and speech possible. prominent feature of the face 4. Olfaction. The sensation of smell occurs when airborne molecules external nose is composed of are drawn into the nasal cavity. hyaline cartilage, although the bridge of the external nose 5. Protection. The respiratory system protects against some consists of bone microorganisms and other pathogens, by preventing them from bone and cartilage are covered entering the body and by removing them from respiratory by connective tissue and skin surfaces. encloses the chamber for air inspiration 9 10 nares or nostrils Because - external learning changes everything. ® Because learning changes everything.® openings of the nose Conchae choanae (funnels) – openings bony ridges on each side into the pharynx of the nasal cavity increase the surface area nasal cavity - extends from of the nasal cavity and the nares to the choanae cause air to churn, so that nasal septum – partition it can be cleansed, humidified, and warmed dividing the nasal cavity into right and left parts deviated nasal septum – occurs when the septum Paranasal sinuses Sagittal section through the air-filled spaces within bone nasal cavity and pharynx. bulges to one side include the maxillary, frontal, ethmoidal, and sphenoidal sinuses, each Nasal Cavity and Pharynx. hard palate - forms the floor of named for the bones in which they are located (a) Sagittal section through the nasal the nasal cavity, separating open into the nasal cavity and are lined with a mucous membrane cavity and pharynx. reduces the weight of the skull, produce mucus, and influence the the nasal cavity from the oral quality of the voice by acting as resonating chambers cavity 11 12 2  18/11/2024 Because learning changes everything.® Because learning changes everything.® Functions of the Nasal Cavity: Serves as a passageway for air - remains open even Nasolacrimal ducts when the mouth is full of food carry tears from eyes Cleans the air - nasal cavity is lined with hairs, which trap some of the large particles of dust in the air open into nasal cavity Humidifies and warms the air - moisture is added to the air as it passes through the nasal cavity Contains the olfactory epithelium - the sensory organ for smell, is located in the most superior part of the nasal cavity Helps determine voice sound - nasal cavity and paranasal Sagittal section through the nasal cavity and pharynx. sinuses are resonating chambers for speech 13 14 Pharynx Because (throat): learning changes everything.® Larynx called voicebox a common passageway for the respiratory and digestive located in the anterior throat systems and extends from the base of the tongue to the trachea Nasopharynx: Functions - maintains an posterior to the choanae and open airway, protects the superior to the soft palate airway during swallowing, takes in air and produces the voice Sagittal section through the nasal cavity and pharynx. Oropharynx: 9 cartilage structures: 3 singles and 3 paired extends from uvula to Uvula: epiglottis Thyroid cartilage – “little grape” takes in food, drink, and air “Adam’s apple” extension of soft palate Laryngopharynx: Cricoid cartilage Pharyngeal tonsil: extends from epiglottis to Epiglottis - piece of esophagus cartilage; flap that prevents aids in defending against swallowed materials from infections food and drink pass through entering larynx Anatomy of the Larynx 15 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 16 Larynx Vocal Folds: force of air determine loudness LOWER RESPIRATORY TRACT: source of voice production Vestibular folds: air moves past them, they tension determines Trachea pitch false vocal cords vibrate, and sound is Windpipe, allows air to flow produced into the lungs true vocal cords membranous tube attached to the larynx Consists of 16 to 20 C- shaped pieces of cartilage called tracheal rings Bronchi divides into right and left main (primary) bronchi in the lungs at the carina Anatomy of the Trachea and Lungs. Vestibular and Vocal Folds. lined with cilia The trachea and lungs and the branching of the bronchi (Far left) The arrow shows the direction of viewing the vestibular and vocal folds. (a) The are shown. Each lung is surrounded by a pleural cavity, contain C-shaped pieces of formed by the visceral and parietal pleurae. relationship of the vestibular folds to the vocal folds and the laryngeal cartilages. (b) cartilage Superior view of the vestibular and vocal folds as seen through a laryngoscope. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 17 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 18 3  18/11/2024 Tracheobronchial Tree Alveoli consists of the trachea and network of air tubes in the sites of external lungs respiration are the structures become smaller and more numerous from alveoli primary bronchi to alveoli small air-filled sacs 1. Primary bronchi where air and blood 2. Lobar (secondary) come into close bronchi contact 3. Segmental (tertiary) bronchi where gas exchange Bronchioles and Alveoli. Bronchioles and Alveoli. 4. Bronchioles occurs A terminal bronchiole branches to form respiratory A terminal bronchiole branches to form 5. Terminal bronchioles respiratory bronchioles, which give rise to bronchioles, which give rise to alveolar ducts. surrounded by Alveoli connect to the alveolar ducts and 6. Respiratory bronchioles alveolar ducts. Alveoli connect to the alveolar ducts and respiratory bronchioles. capillaries respiratory bronchioles. The alveolar ducts end as 7. Alveolar ducts two or three alveolar sacs. The alveolar ducts end as two or three 300 million in lungs 8. Alveoli alveolar sacs. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 19 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 20 Respiratory Membrane in lungs where gas exchange Thoracic Wall and Muscles of Pulmonary between air and blood occurs Ventilation: formed by walls of alveoli and capillaries alveolar ducts and respiratory Thoracic wall bronchioles also contribute very thin for diffusion of gases Thoracic vertebrae Surfactant – chemical secreted by specialized secretory cells within the wall Ribs of alveoli that reduces the tendency of Coastal cartilages alveoli to recoil Layers of Respiratory Membrane: Sternum Alveolus and the Respiratory Membrane. Thin layer of fluid from alveolus (a) Section of an alveolus, showing the air- Associated muscles Alveolar epithelium (simple squamous) filled interior and thin walls composed of Basement membrane of alveolar epithelium simple squamous epithelium. The alveolus is surrounded by elastic Thin interstitial space Basement membrane of capillary connective tissue and blood capillaries. Thoracic cavity – space enclosed by thoracic wall endothelium (b) O2 and CO2 diffuse across the six thin layers of the respiratory membrane. and diaphragm Capillary endothelium (simple squamous) Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 21 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 22 Lungs Primary organ of respiration Right lung has 3 lobes Blood Supply to Lungs: Cone shaped Left lung has 2 lobes The base rests on the diaphragm Contains many air passageways (divisions) Oxygenated blood has passed through the lungs and The apex extends above the clavicle picked up O2 Deoxygenated blood has passed through the tissues and released some of its O2. Pulmonary arteries carry deoxygenated blood to pulmonary capillaries. Blood becomes oxygenated and returns to the heart Lungs, Lung Lobes, and Bronchi. through pulmonary veins. The right lung is divided into three lobes by the horizontal and oblique fissures. The left lung is divided into two lobes by the oblique fissure. A main bronchus supplies each lung, a lobar bronchus supplies each lung lobe, and segmental bronchi supply the bronchopulmonary segments (not visible). Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 23 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 24 4  18/11/2024 Pleural Cavities and Membranes Lymphatic Supply to the Lungs Functions of pleural fluid: 1) It acts as a Superficial lymphatic vessels: lubricant, allowing the visceral and deep to the connective tissue parietal pleurae to that surrounds each lung slide past each other as the lungs drain lymph from the and thorax change superficial lung tissue and the shape during visceral pleura. respiration Deep lymphatic vessels: 2) it helps hold the pleural membranes follow the bronchi together Pleural Cavities and Membranes. drain lymph from the bronchi Transverse section of the thorax, showing the relationship of the pleural cavities and associated connective to the thoracic organs. Each lung is surrounded by a pleural cavity. The parietal tissues pleura lines the wall of each pleural cavity, and the visceral pleura covers the surface of the lungs. The space between the parietal and visceral pleurae is small and filled with pleural fluid. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 25 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 26 BEHAVIOR OF GASES AND PULMONARY Changes in Thoracic Volume VENTILATION Ventilation – movement of air into and out of the lungs 1. action of the muscles or respiration 2. air pressure gradients Muscles of Ventilation to change the volume of the thoracic activity, which allows for air to flow into and out of the lungs Muscles of Inspiration (inhalation) – to increase the volume of the thoracic cavity; diaphragm, external intercostals, pectoralis minor, scalene muscles Muscles of Expiration (exhalation) – decrease thoracic volume by depressing the ribs and sternum; internal intercostals, transverse thoracis a. Elevation of the rib in the “bucket-handle” movement increases thoracic volume laterally and in the “pump-handle” movement it increases thoracic volume anteriorly. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 27 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 28 Ventilation and Respiratory Volumes Ventilation or breathing, process of moving air into and out of the lungs Phases of ventilation: (1) Inspiration or inhalation - movement of air into the lungs (2) Expiration or exhalation - movement of air out of the lungs regulated by changes in thoracic volume, which produce changes in air pressure within the lungs. b. As the rib rotates back to its resting position in the ”bucket-handle” movement, it decreases the lateral thoracic volume, and in the “pump-handle” movement, it decreases anterior-posterior thoracic volume. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 29 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 30 5  18/11/2024 two physical principles govern the flow of air into and out of the lungs Quiet versus Labored Breathing: Pressure Changes and Air Flow Quiet breathing - expiration is a passive process due to elastic tissue in the thorax wall and the lungs 1. Changes in volume result in changes in pressure Labored inspiration - more air moves into the lungs as the volume of a container increases, the pressure because all of the inspiratory muscles are active within the container decreases; the opposite is also Labored expiration - more air moves out of the true lungs due to the forceful contraction of the 2. Air flows from an area of higher pressure to an internal intercostals and the abdominal muscles area of lower pressure air flows from the area of higher pressure to lower pressure Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 31 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 32 Measurements of Lung Function: Respiratory volumes: Tidal volume (TV): Pulmonary Volumes and Capacities normal volume of air inspired and expired during quiet breathing; 500 ml Expiratory reserve volume (ERV): Spirometry - process of measuring volumes of air that volume of air that can be expired forcefully after a normal expiration move into and out of the respiratory system (about 1100 mL) Spirometer - device that measures respiratory Residual volume (RV): volumes volume of air remaining in lungs after a maximal expiration (about 1200 mL) Respiratory volumes - measures of the amount of Inspiratory reserve volume (IRV): air movement during different portions of ventilation volume of air that can be inspired forcefully after a normal inspiration Respiratory capacities - sum of two or more about (3000 ml) respiratory volumes Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 33 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 34 Respiratory capacities - sum of two or more pulmonary volumes 1. Inspiratory capacity - tidal volume plus the inspiratory reserve volume. This is the amount of air a person can inspire maximally after a normal expiration (about 3500 mL at rest). 2. Vital capacity - sum of the inspiratory reserve volume, the tidal volume, and the expiratory reserve volume. It is the maximum volume of air that a person can expel from the respiratory tract after a maximum inspiration (about 4600 mL). 3. Functional residual capacity - expiratory reserve volume plus the residual volume. This is the amount of air remaining in the lungs at the end of a normal expiration (about 2300 mL at rest). 4. Total lung capacity - sum of the inspiratory and expiratory reserves and the tidal and residual volumes (about 5800 mL). The total lung Respiratory Volumes and Respiratory Capacities. capacity is also equal to the vital capacity plus the residual volume. The tidal volume shown here is during resting conditions. Respiratory volumes are measurements of the volume of air moved into and out of the lungs during breathing. Respiratory capacities are the sum of two or more respiratory volumes. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 35 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 36 6  18/11/2024 Alveolar Ventilation Factors Affecting Ventilation: measure of the volume of air available for gas exchange per minute Gender – 20-25% less in adult females than adult only a portion of each breath reaches the alveoli for gas exchange males remaining area where no gas exchange occurs is called the dead space Age – maximum amount in young adults, decreases in elderly Anatomical dead space - areas include all the structures of the upper respiratory tract, and structures of the Body Size – greater vital capacity in tall than short lower respiratory tract to the terminal bronchioles people, in thin than obese people Physiological dead space - combination of the anatomical Physical Fitness - well-trained athletes have vital dead space and the volume of any alveoli with capacity of 30-40% above that of untrained lower than normal gas exchange people Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 37 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 38 PHYSIOLOGY OF THE RESPIRATORY SYSTEM Partial Pressure pressure exerted by a specific gas in a mixture of gases total atmospheric pressure of all gases at sea level = 760 mm Hg atmosphere is 21% O2 PO2, partial pressure for O2 0.21 x 760 mm Hg =160 mm Hg Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 39 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 40 Mechanisms of Alveolar Ventilation 1. At the end of expiration, alveolar Factors affecting Alveolar Ventilation: pressure, which is the air pressure within the alveoli, is equal to atmospheric Lung Recoil pressure, which is the air pressure outside the body. No air moves into or tendency for an expanded lung to decrease in size out of the lungs because alveolar occurs during quiet expiration pressure and atmospheric pressure are equal occurs for two reasons – elastic recoil and surface tension 2. During inspiration, the volume of the elastic recoil – elastic fibers within the lungs and thoracic wall return thoracic cavity increases when the muscles of inspiration contract. The to their original shape and size once tension is released increased thoracic volume decreases the Lung recoil – due to hydrogen bonding within alveoli pressure in the alveoli below atmospheric pressure. Air flows into the alveoli Surfactant - a mixture of lipoproteins; produced by secretory cells 3. At the end of inspiration, the thorax and of the alveoli; a fluid layer on the surface lining the alveoli alveoli stop expanding. When the alveolar reduces surface tension; keeps lungs from collapsing pressure and atmospheric pressure become equal, airflow stops． Pleural Pressure 4. During expiration, the thoracic cavity volume decreases. Consequently, alveolar pressure in the pleural cavity pressure increases above atmospheric Alveolar Pressure Changes During Inspiration and Expiration. pressure, and air flows out of the alveoli． less than alveolar pressure The combined space of all the alveoli is represented by a large As expiration ends, the decrease in “bubble” (blue). The alveoli are actually microscopic and cannot be thoracic volume stops, and the keeps the alveoli from collapsing seen in the illustration. process repeats, beginning at step 1. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 41 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 42 7  18/11/2024 Once at equilibrium, At the alveoli, O2 diffuses the gases stop into and CO2 diffuses out diffusing of the blood Respiratory Membrane Thickness Increased thickness decreases rate of Blood in pulmonary veins diffusion of gases At the tissues, O2 diffuses Pulmonary edema decreases diffusion out and CO2 diffuses into Rate of gas exchange is decreased the blood Once at equilibrium, the gases stop diffusing O2 exchange is affected before CO2 because CO2 diffuse more easily Gas Exchange. than O2 Differences in partial pressure are responsible for the exchange of O2 and CO2 that occurs between the alveoli and the pulmonary capillaries and between the tissues and the tissue capillaries. Access the text alternative for slide images Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 43 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 44 OXYGEN AND CARBON DIOXIDE Respiratory Membrane Surface Area TRANSPORT IN THE BLOOD total surface area of respiratory membrane is about 70 square meters Hemoglobin may be decreased due to removal of lung tissue, a complex protein occupying about the one-third of the destruction from cancer, emphysema, total volume of the cytoplasm of red blood cells tuberculosis consists of four subunits, each containing one iron-based exchange of gases is significantly restricted heme group which binds O2. CO2 can bind to the protein portion of hemoglobin. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 45 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 46 Carbon Dioxide Transport and Blood pH Oxygen Transport in Blood CO2 diffuses from cells into capillaries CO2 enters blood and is transported in three ways: O2 diffuses through the respiratory membrane into 1. 7% is dissolved in blood plasma the blood and is transported to all the cells of 2. 93% enters red blood cells: 23% is bound to hemoglobin the body 3. 70% is transported as bicarbonate ions 98.5% is transported reversibly bound to hemoglobin within red blood cells CO2 reacts with water to form carbonic acid CO2 + H2O ↔ H2CO3 1.5% is dissolved in the plasma Carbonic acid dissociates into a hydrogen ion and a bicarbonate ion H2CO3 ↔ H+ + HCO3- Carbonic anhydrase (RBC) increases rate of CO2 reacting with water As CO2 levels increase, blood pH decreases Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 47 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 48 8  18/11/2024 Summary of Gas Transport REGULATION OF VENTILATION Gas Exchange in the Tissues and in the Lungs. (a) In the tissues, CO2 diffuses into red blood cells, where the enzyme Respiratory rate is regulated to maintain gas carbonic anhydrase (CA) is located. CA catalyzes the reaction of CO2 concentrations in the blood within normal with H2O to form carbonic acid (H2CO3). H2CO3 dissociates to form limits. bicarbonate ions (HCO3 – ) and hydrogen ions (H+). Oxygen is released from hemoglobin (Hb) and The body is particularly sensitive to changes diffuses into tissue cells. in CO2 levels and blood pH. (a) In the lungs, CO2 diffuses from red blood cells into the alveoli. CA catalyzes the formation of CO2 and H2O from H2CO3. H+ and HCO3 – Neurons in the medulla oblongata control combine to replace H2CO3. Oxygen diffuses into red blood cells and the rate of ventilation through stimulation of binds to hemoglobin. the muscles of respiration. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 49 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 50 Respiratory Areas in the Brainstem Medullary respiratory center in the medulla oblongata consists of: Generation of Rhythmic Ventilation Dorsal respiratory group (DRG) - most active during inspiration 1. Starting inspiration - medullary respiratory center Ventral respiratory group (VRG) - establishes the basic rhythm of ventilation active during inspiration and expiration Receives stimulation from receptors for blood gas levels, blood VRG contains the pre-Bötzinger complex which is believed to temperature, movements of muscles and joints, and emotions establish the basic rhythm of respiration Input from receptors causes action potentials that stimulate Pontine respiratory group - a respiratory muscles. collection of neurons in the pons that helps regulate respiration rate Precise function is unknown 2. Increasing inspiration - once inspiration begins, more and some neurons are active during more neurons are activated resulting in progressively stronger inspiration, some during stimulation of the respiratory muscles. Lasts about 2 seconds. Respiratory Structures in the Brainstem. expiration, and others during both inspiration and expiration Specific structures in the brainstem correlate with the nerves that innervate the muscles of respiration. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 51 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 52 Generation of Rhythmic Ventilation Factors Affecting Respiratory Rate Decrease in Po2 (hypoxia) causes an increase in 3. Stopping inspiration - neurons stimulating muscles of respiration also stimulate neurons responsible for stopping respiratory rate. inspiration. Increase in Pco2 (hypercapnia) causes an increase in rate They receive input from the pontine respiratory group and stretch and depth of ventilation. receptors in the lungs. Decrease in Pco2 (hypocapnia ) causes a decrease in Inhibitory neurons inhibits respiratory muscles and relaxe respiratory rate of ventilation. muscles. Chemoreceptors in the medulla oblongata and blood Results in expiration. Lasts about 3 seconds. vessels near the heart respond to changes in Pco2 and pH. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 53 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 54 9  18/11/2024 Factors Affecting Respiratory Rate Factors Affecting Respiratory Rate Increases in CO2 cause decreases in pH. Central chemoreactors in the medulla oblongata detect The Hering-Breuer reflex limits the depth of changes in CO2. inspiration preventing over-inflation of the lungs. Carotid and aortic bodies in blood vessels detect changes in pH. Depends on stretch receptors in the bronchi and Decreases in pH cause increases in the rate and depth of bronchioles. breathing which restores CO2 and pH to normal levels. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 55 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 56 Regulation of Blood pH Nervous and Chemical Mechanisms of Breathing Regulation of Blood pH. (1) Blood pH is in its normal range. (2) Blood pH increases outside its normal range, which disturbs homeostasis. (3) The control centers for blood pH, the medullary chemoreceptors, detect an increase in blood pH (blood becomes more basic) and respond to the increased pH by signaling a decreased breathing rate. (4) The effectors, the diaphragm and other respiratory muscles, respond by slowing their contraction rate, which lowers the rate of breathing. Nervous and Chemical Mechanisms of (5) As a result, more CO2 is retained, which Breathing. causes pH to drop (blood becomes more acidic). Several regulatory mechanisms affect the rate and depth of breathing. A plus sign indicates (6) Blood pH returns to its normal range and that the mechanism increases breathing and a homeostasis is maintained. Observe the minus sign indicates that it results in a responses to a decrease in blood pH by decrease in breathing. following the red arrows. Access the text alternative for slide images Access the text alternative for slide images Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 57 Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 58 10