Respiratory System PDF

The Respiratory System _____________________________________ is gas exchange: O2 and CO2 Occurs between atmosphere and body cells Cells need O2 for aerobic ATP production and need to dispose of CO2 that process produces The _____________________________________provides the means for gas...

The Respiratory System _____________________________________ is gas exchange: O2 and CO2 Occurs between atmosphere and body cells Cells need O2 for aerobic ATP production and need to dispose of CO2 that process produces The _____________________________________provides the means for gas exchange Consists of respiratory passageways in head, neck, and trunk, and the lungs 23.1a General Functions of the Respiratory System _____________________________________ Air moves between atmosphere and alveoli as we breathe _____________________________________ Oxygen diffuses from alveoli into blood Carbon dioxide diffuses from blood into alveoli _____________________________________ Olfactory receptors in superior nasal cavity _____________________________________ Air moves across vocal cords of the larynx (voice box) Vocal cords vibrate, producing sound 23.1b General Organization of the Respiratory System Structural organization _____________________________________ Nose, nasal cavity, pharynx, larynx _____________________________________ _____________________________________ Trachea, bronchi, bronchioles, alveolar ducts, alveoli Functional organization Structures of the _____________________________________ transport air Nose to terminal bronchioles Structures of the _____________________________________participate in gas exchange Respiratory bronchioles, alveolar ducts, alveoli 23.1c Respiratory Mucosa 1 _____________________________________ = _____________________________________respiratory lining Epithelium resting on a basement membrane Underlying lamina propria made of areolar connective tissue Gets progressively thinner from nasal cavity to lungs 23.1c Respiratory Mucosa 2 Mucous secretions Produced from secretions of _____________________________________of epithelial lining Mucous and serous glands of the lamina propria Contain _____________________________________protein  Increases mucus viscosity and serves to trap dust, dirt, pollen, etc. Contains defenses against microbes Called _____________________________________ when coughed up with saliva and trapped substances 23.2a Nose and Nasal Cavity 2 _____________________________________from nostrils to choanae _____________________________________– paired openings that lead to pharynx Floor formed by palate Roof made of nasal, frontal, ethmoid, and sphenoid bones _____________________________________divides left and right sides 23.2a Nose and Nasal Cavity 3 The _____________________________________ Three paired, bony projections on lateral walls of nasal cavity Produce turbulence in inhaled air Partition the nasal cavity into separate passages Each passage called a _____________________________________ 23.2a Nose and Nasal Cavity 4 Nasal cavity parts _____________________________________just inside nostrils _____________________________________ Superior part of nasal cavity containing olfactory epithelium Airborne molecules stimulate receptors for odor detection _____________________________________ Lined by pseudostratified ciliated columnar epithelium Has an extensive vascular network _____________________________________ common due to large numbers of superficial vessels 23.2a Nose and Nasal Cavity 5 Nasal cavity conditions the air (warms, cleanses, and humidifies) Air is warmed by extensive blood vessels Mucus traps dust, microbes, and foreign material Cilia sweep mucous toward the pharynx to be swallowed Moist environment humidifies Air turbulence created by conchae enhances all three processes Paranasal Sinuses spaces within skull bones Lined by pseudostratified ciliated columnar epithelium Mucus swept into pharynx and swallowed 23.2c Pharynx 1 _____________________________________ (throat)  Funnel-shaped passageway posterior to nasal cavity, oral cavity, and larynx Lateral walls composed of skeletal muscles Partitioned into Nasopharynx Oropharynx Laryngopharynx 23.2c Pharynx 2 _____________________________________ most superior part of pharynx Posterior to nasal cavity, superior to soft palate Lined by pseudostratified ciliated columnar epithelium An air passage—not for food Soft palate elevates during swallowing, blocking food or drink Connects to middle ear via _____________________________________(eustachian)_____________________________ ________ Opening tubes allows equalization of pressure on each side of tympanic membrane 23.2c Pharynx 3 _____________________________________middle pharyngeal region Posterior to oral cavity Extends from soft palate to hyoid bone Passageway for both food and air Lined by nonkeratinized stratified squamous epithelium 23.2c Pharynx 4 _____________________________________inferior, narrow region of pharynx Posterior to the larynx From level of hyoid down to esophagus Passageway for both food and air Lined by nonkeratinized stratified squamous epithelium 23.2d Larynx 1 _____________________________________(voice box): Cylindrical airway between laryngopharynx and trachea Functions of the larynx: 1. _____________________________________ Vocal folds vibrate during expiration 2. _____________________________________ 3. Prevents ingested materials from entering respiratory tract Epiglottis covers superior opening during swallowing 23.2d Larynx 2 Functions of the larynx (continued) 1. Assists in increasing pressure in abdominal cavity _____________________________________vocal folds close off during contraction of abdominal muscles Increased pressure facilitates urination, defecation, childbirth 2. _____________________________________ Help remove irritants from nasal cavity or lower respiratory tract Abdominal muscles contract increasing thoracic pressure Vocal cords are forcibly opened by pressure from below Explosive blast of exhaled air is a cough or sneeze 23.2d Larynx 6 Larynx anatomy (continued) _____________________________________(true vocal cords) Produce sound when air passes between them Opening between ligaments = _____________________________________ _____________________________________+ _____________________________________= _____________________________________ _____________________________________(false vocal cords) Play no role in sound production; protect vocal cords 23.2d Larynx 8 _____________________________________vocal cord vibration Intrinsic laryngeal muscles narrow opening of rima glottidis Air is forced past vocal cords during expiration _____________________________________of voice determined by length, thickness of vocal cords Males have longer and thicker folds, and so deeper voices Folds increase in length with growth, deepening range _____________________________________ (frequency) determined by tension on vocal cords Increased tension = folds vibrate more = higher pitch Regulated by intrinsic laryngeal muscles _____________________________________depends on force of air passing across vocal cords More air = louder sound 23.3 Lower Respiratory Tract Includes conducting pathways from trachea to terminal bronchioles Includes structures involved in gas exchange: respiratory bronchioles, alveolar ducts, and alveoli 23.3a Trachea 1 _____________________________________ (windpipe): open tube connecting larynx to main bronchi Gross anatomy of the trachea Anterior to esophagus, posterior to part of sternum _____________________________________support anterior and lateral walls C-shaped rings of hyaline cartilages Ensheathed in perichondrium and dense fibrous membrane Ensure trachea is always open 23.3a Trachea 2 Gross anatomy of the trachea_____________________________________(continued) _____________________________________ internal ridge at inferior end of trachea (where it splits) containing many sensory receptors Initiates cough reflex when irritants are present Histology of the Tracheal Wall Layers, inner to outer: _____________________________________pseudostratified ciliated columnar epithelium and lamina propria _____________________________________areolar connective tissue with blood vessels, nerves, serous and mucous glands, lymphatic tissue 23.3b Bronchial Tree 1 _____________________________________system of highly branched air passages Originates at main bronchi, branches to more narrow tubes Ends in small bronchiole passageways Gross anatomy of bronchial tree Trachea splits into right and left _____________________________________(primary bronchi) Each bronchus enters a lung on its medial surface Right bronchus shorter, wider, and more vertically oriented Foreign particles more likely to lodge here 23.3b Bronchial Tree 3 Histology of the bronchial tree Main bronchi are supported by incomplete rings of hyaline cartilage (keep them open) Wall support (cartilage) lessens as bronchi divide Bronchioles have no cartilage Have proportionally thicker layer of smooth muscle Muscle contraction narrows bronchiole diameter _____________________________________ =_____________________________________less air through bronchial tree (less entry of potentially harmful substances) Muscle relaxation increases bronchiole diameter  _____________________________________= more air through the bronchial tree 23.3c Respiratory Zone: Respiratory Bronchioles, Alveolar Ducts, and Alveoli 1 Respiratory zone structures are microscopic _____________________________________subdivide to _____________________________________ Alveolar ducts lead to _____________________________________ clusters of alveoli _____________________________________ = saccular out pocketings Epithelium Respiratory bronchioles lined with simple cuboidal epithelium Alveoli and alveolar ducts lined by simple squamous Thinness facilitates gas exchange 23.3c Respiratory Zone: Respiratory Bronchioles, Alveolar Ducts, and Alveoli 3 Cell types of alveolar wall _____________________________________ (squamous alveolar cells) Most common of the two cell types making up alveolar wall Form the _____________________________________of the respiratory membrane _____________________________________(septal cells) Secrete oily _____________________________________ Coats inside of alveolus and opposes collapse during expiration _____________________________________(dust cells) Leukocytes that engulf microorganisms Either fixed in alveolar wall or free to migrate 23.3d Respiratory Membrane The _____________________________________ Thin barrier separating air in alveoli and blood in pulmonary capillaries Consists of Alveolar epithelium and its basement membrane Capillary epithelium and its basement membrane Basement membranes are fused Oxygen diffuses from alveolus into capillaries Erythrocytes become oxygenated Carbon dioxide diffuses from blood to alveolus Expired to external environment 23.4a Gross Anatomy of the Lung 1 House bronchial tree and all respiratory portions of respiratory system Each lung has a conical shape Wide concave _____________________________________atop diaphragm  _____________________________________ points superiorly just behind clavicle 23.4a Gross Anatomy of the Lung 3 Right lung is larger and wider than left lung Has three lobes divided by two fissures Left lung is smaller than right due to heart’s position Has two lobes divided by one fissure 23.4b Circulation to and Innervation of the Lungs 1 _____________________________________ Two types of circulation in the lungs Pulmonary circulation Bronchial circulation _____________________________________replenishes O2, eliminates CO2 Pulmonary arteries carry deoxygenated blood to pulmonary capillaries Blood is reoxygenated Blood enters pulmonary venules and veins, returns to left atrium 23.4b Circulation to and Innervation of the Lungs 2 Blood supply_____________________________________(continued) _____________________________________transports oxygenated blood to tissues of lungs _____________________________________(3 or 4) branch off descending aorta _____________________________________collect venous blood 23.4b Circulation to and Innervation of the Lungs 4 Innervation of the respiratory system Autonomic nervous system innervates smooth muscles and glands of respiratory structures Sympathetic input from T1–T5 generally causes bronchodilation Parasympathetic from vagus causes bronchoconstriction 23.4c Pleural Membranes and Pleural Cavity 1 _____________________________________serous membrane lining lung surfaces and thoracic wall Composed of simple squamous epithelium + areolar CT _____________________________________ adheres to lung surface _____________________________________lines Internal thoracic walls Lateral surface of mediastinum Superior surface of diaphragm Each lung enclosed in a separate visceral pleural membrane Helps limit spread of infections 23.4c Pleural Membranes and Pleural Cavity 2 _____________________________________ Located between visceral and parietal serous membranes When lungs are inflated, considered a potential space Visceral and parietal layers almost touching Serous fluid produced by serous membranes Covers pleural cavity surface Lubricates, allowing pleural surfaces to slide by easily Drained continuously by lymph 23.4d How Lungs Remain Inflated _____________________________________(between membranes) is low Chest wall configured to expand outward Lungs cling to chest wall due to serous fluid’s surface tension Elastic tissue of lungs pulls inward Because _____________________________________(in alveoli) is greater than intrapleural pressure, lungs remain inflated Lungs experience an “outward pull” from the chest wall 23.5 Respiration: Pulmonary Ventilation 1 _____________________________________ (exchange of gases between atmosphere and body’s cells) involves four processes _____________________________________movement of gases between atmosphere and alveoli _____________________________________: exchange of gases between alveoli and blood _____________________________________transport of gases in blood between lungs and systemic cells _____________________________________: exchange of respiratory gases between the blood and the systemic cells 23.5 Respiration: Pulmonary Ventilation 2 Net movement of respiratory gases 1) Air containing O2 is inhaled into alveoli during inspiration 2) O2 diffuses from alveoli into pulmonary capillaries 3) Blood from lungs transports O2 to systemic cells 4) O2 diffuses from systemic capillaries into systemic cells 5) CO2 diffuses from systemic cells into systemic capillaries 6) CO2 is transported in blood from systemic cells to lungs 7) CO2 diffuses from pulmonary capillaries into alveoli 8) Air containing CO2 is exhaled from alveoli into the atmosphere 23.5a Introduction to Pulmonary Ventilation _____________________________________(breathing): air movement between atmosphere and alveoli  Consists of two cyclic phases _____________________________________ brings air into the lungs (inhalation) _____________________________________ forces air out of the lungs (exhalation) _____________________________________ rhythmic breathing at rest _____________________________________ vigorous breathing accompanies exercise Autonomic nuclei in brainstem regulate breathing activity Skeletal muscles contract and relax changing thorax volume Volume changes result in changes in pressure gradient between lungs and atmosphere Air moves down its pressure gradient Air enters lung during inspiration; exits during expiration Thoracic Cavity Dimensional Changes Associated with Breathing 1. Diaphragm movement Flattens (by moving inferiorly) when contracted When relaxed, returns to original position, vertical dimensions decrease 2. Rib cage movement elevation widens thoracic cavity in inspiration depression narrows thoracic cavity in expiration 3. Sternum movement Moves anteriorly in inspiration Moves posteriorly in expiration Boyle’s Law _____________________________________Relationship of volume and pressure At constant temperature, pressure (P) of a gas decreases if volume (V) of the container increases, and vice versa P1 and V1 represent initial conditions and P2 and V2 the changed conditions P1V1 = P2V2 Inverse relationship between gas pressure and volume From Table 23.1 Pressure Gradients An air pressure gradient exists when force per unit area is greater in one place than another If the two places are interconnected, air flows from high to low pressure until pressure is equal 23.5b Mechanics of Breathing 5 Volumes and pressures associated with breathing _____________________________________pressure of air in environment Changes with altitude Increased altitude = “thinner air” = lower pressure Unchanged in process of breathing _____________________________________:_____________________________________pressure in alveoli Fluctuates with breathing May be higher, lower, or equal to atmospheric pressure 23.5b Mechanics of Breathing 6 Volumes and pressures associated with breathing_____________________________________(cont’d.) Volume changes create pressure changes and air flows down its pressure gradient During inspiration: thoracic volume increases, thoracic pressure decreases, so air flows in During expiration: thoracic volume decreases, thoracic pressure increases, so air flows out 23.5c Nervous Control of Breathing 1 Autonomic nuclei within the brain coordinate breathing _____________________________________of the brainstem Medullary respiratory center contains two groups Pontine respiratory center in pons Brainstem neurons influence respiratory muscles 23.5c Nervous Control of Breathing 2 Chemoreceptors monitor changes in concentrations of H+, PCO2 and PO2 _____________________________________in medulla monitor pH of CSF _____________________________________are in aortic and carotid bodies Stimulated by changes in H+ or respiratory gases in blood 23.5c Nervous Control of Breathing 7 Reflexes that alter breathing rate and depth_____________________________________(cont’d.) Blood PCO2 is most important stimulus affecting breathing Raising blood PCO2 by 5 mm Hg causes doubling of breathing rate CO2 fluctuations influence sensitive central chemoreceptors CO2 combines with water to form carbonic acid in CSF CSF lacks protein buffers and so its pH change triggers reflexes Blood PO2 is not a sensitive regulator of breathing Arterial oxygen must decrease from 95 to 60 mm Hg to have major effect independent of PCO2 23.5e Minute Ventilation and Alveolar Ventilation 1 _____________________________________= amount of air per breath _____________________________________= number of breaths per minute _____________________________________ Process of moving air into and out of the lungs Amount of air moved between atmosphere and alveoli in 1 minute Tidal volume × Respiration rate = Minute ventilation 500 mL × 12 breaths/min = 6 L/ minute (typical amount) 23.5f Measuring Respiratory Function 1 _____________________________________measures respiratory volume Four volumes measured by spirometry _____________________________________ amount of air inhaled or exhaled per breath during quiet breathing _____________________________________ amount of air that can be forcibly inhaled beyond the tidal volume Measure of compliance _____________________________________amount that can be forcibly exhaled beyond tidal volume Measure of elasticity _____________________________________amount of air left in the lungs after the most forceful expiration 23.5f Measuring Respiratory Function 2 Four capacities calculated from respiratory volumes _____________________________________ Tidal volume + inspiratory and expiratory reserve volumes Total amount of air a person can exchange through forced breathing _____________________________________ Sum of all volumes, including residual volume Maximum volume of air that the lungs can hold 23.5f Measuring Respiratory Function 3 Additional respiratory measurements—rates of air movement _____________________________________ Percent of vital capacity that can be expelled in a set period of time FEV1 = percentage expelled in one second 75 to 85% of vital capacity in a healthy person Less in emphysema patients and others with poor expiration Helps distinguish: _____________________________________, such as emphysema, where it is difficult to expire _____________________________________, such as pulmonary fibrosis, where it is difficult to inspire 23.6a Chemical Principles of Gas Exchange 1 _____________________________________pressure exerted by each gas within a mixture of gases, measured in mm Hg Written with P followed by gas symbol (that is, PO2 ) Each gas moves independently down its partial pressure gradient during gas exchange 23.6a Chemical Principles of Gas Exchange 2 Partial pressure_____________________________________(continued) Total pressure × % of gas = Partial pressure of that gas Nitrogen is 78.6% of the gas in air 760 mm HG × 78.6% = 597 mm Hg = partial pressure of nitrogen Partial pressures added together equal the total atmospheric pressure 23.6a Chemical Principles of Gas Exchange 4 Relevant partial pressures in the body_____________________________________(continued) In systemic cells, partial pressures of gases reflect cellular respiration (use of O2, production of CO2) The percentage of O2 lower and CO2 higher than in alveoli Under resting, normal conditions the partial pressures remain constant In circulating blood, gas partial pressures are not constant O2 enters blood in pulmonary capillaries; CO2 leaves O2 leaves blood in systemic capillaries; CO2 enters 23.6a Chemical Principles of Gas Exchange 5 _____________________________________ Gradient exists when partial pressure for a gas is higher in one region of the respiratory system than another Gas moves from region of higher partial pressure to region of lower partial pressure until pressures become equal Both types of gas exchange depend on gradients Alveolar gas exchange: between blood in pulmonary capillaries and alveoli Systemic gas exchange: between blood in systemic capillaries and systemic cells 23.6b Pulmonary Gas Exchange 1 Movement of O2 PO2 in alveoli is 104 mm Hg PO2 of blood entering pulmonary capillaries is 40 mm Hg Oxygen diffuses across respiratory membrane from alveoli into the capillaries Moves down its partial pressure gradient Continues until blood PO2 is equal to that of alveoli Levels in alveoli remain constant as fresh air continuously enters 23.6b Pulmonary Gas Exchange 2 Movement of CO2 PCO2 in alveoli is 40 mm Hg PCO2 in blood of pulmonary capillaries is 45 mm Hg Carbon dioxide diffuses from blood to alveoli Moves down its partial pressure gradient Continues until blood levels equal alveoli levels Levels in alveoli remain constant 23.6c Tissue Gas Exchange 1 Oxygen diffuses out of systemic capillaries to enter systemic cells Partial pressure gradient drives the process PO2 in systemic cells 40 mm Hg PO2 in systemic capillaries is 95 mm Hg Continues until blood PO2 is 40 mm Hg Systemic cell PO2 stays fairly constant Oxygen delivered at same rate it is used unless engaging in strenuous activity 23.6c Tissue Gas Exchange 2 Movement of CO2 Diffuses from systemic cells to blood Partial pressure gradient driving process PCO2 in systemic cells 45mm Hg PCO2 in systemic capillaries 40 mm Hg Diffusion continuing until blood PCO2 is 45 mm Hg 23.7a Oxygen Transport Oxygen is transported in two ways: dissolved in plasma Very little is transported this way Attached to hemoglobin The iron atom attaches oxygen About 98% of O2 in blood is bound to hemoglobin _____________________________________ (with oxygen bound) _____________________________________ (without bound oxygen) 23.7c Hemoglobin as a Transport Molecule 2 Hemoglobin and Binding of Oxygen Each hemoglobin can bind up to four O2 molecules One on each iron atom in the hemoglobin molecule Percent O2 saturation of hemoglobin is crucial It is the amount of oxygen bound to available hemoglobin Saturation increases as PO2 increases _____________________________________each O2 that binds causes a change in hemoglobin making it easier for next O2 to bind 23.7b Carbon Dioxide Transport Carbon dioxide has three means of transport As CO2 dissolved in plasma (7%) As CO2 attached to amine group of globin portion of hemoglobin (23%) carbaminohemoglobin  As bicarbonate dissolved in plasma (70%) CO2 diffuses into erythrocytes, reacts with water to form bicarbonate and hydrogen ion