Test Bank for Chapter 18 The Respiratory System

Chapter 18: The Respiratory System
Overview of the Respiratory System
Respiration Supplies the Body with O2 and Removes CO2
 Respiration: process of supplying body with O2 and removing CO2 with 5 basic steps
 Ventilation (breathing): air flows into and out of the lungs
 Inspiration (inhalation): movement of air into lungs  O2 enters lungs
 Expiration (exhalation): movement of air out of lungs  CO2 leaves lungs
 Pulmonary gas exchange: gases exchanged b/w alveoli (air sacs) of lungs & blood in pulmonary
capillaries
 Pulmonary capillaries gain O2 and lose CO2
 Transport of O2 and CO2 by the blood: blood carries O2 from the lungs to tissue cells & CO2 from tissue
cells to the lungs
 Systemic gas exchange: gases exchanged b/w blood in systemic capillaries and tissue cells
 Systemic capillary blood loses O2 and gains CO2
 Cellular respiration: cells consume O2 & give off CO2 as metabolic reactions break down nutrient
molecules in order to produce ATP
The Respiratory System Is Comprised of Several Organs
 Respiratory system: consists of the nose, pharynx, larynx, trachea, primary bronchi, and lungs
 Lungs consist: smaller bronchi, bronchioles, and microscopic air sacs (alveoli)
 Alveoli: sites of gas exchange b/w air & blood
 All structures that carry air to & from the alveoli are referred as airways
The Respiratory Mucosa Produces Mucus That Traps Particles and Lubricates the Airways
 Airways from nose to bronchioles are lines by mucosa (mucous membrane) - a layer of epithetical cells &
underlying layer of connective tissue
 Epithelium parts of airways contains: ciliated cells (cells w/ cilia attached) & goblet cells that secrete
mucus
 Mucus: sticky secretion that traps inhaled particles & serves as lubricant for lining of respiratory
tract
 Cilia: short hair-like projections that extend from the surface of cell
 Cilia in nose moves mucus and trapped particles down toward pharynx; cilia in larynx, trachea,
bronchi, and bronchioles move up toward pharynx
 Movement of mucus along respiratory tract toward pharynx is called mucocilary escalator
 Once in pharynx: substances can be swallowed or expectorated (spit out)
 Movement of cilia paralyzed by nicotine
 Only cilia make contact w/ mucus
 Periciliary fluid: thin, watery saline layer beneath mucus & surround remaining parts of cilia
 Facilitates moves of mucus along respiratory tract
 Volume is reduced: mucus thickens & entangles cilia  cilia unable to move mucus & clogs airways
(Cystic Fibrosis)
The Nose Brings Air into the Respiratory System
 Airways being with nose – site where air normally enters respiratory system
 Space w/in nose called nasal cavity which opens in the interior as the nostrils
 Major function: filter, warm, and humidify incoming air
 Air enters nostrils: passes coarse hairs that traps & filter out large dust particles

,  Air flows over shelf-like extensions of bone called nasal conchae that extend from wall of nasal
cavity
 Conchae cause inhaled air to become turbulent
 Air swirls: airborne particles are filtered out as they come in contact w/ mucus that lines nasal
cavity
 Allows incoming air to be warmed by blood circulation in abundant capillaries & be humidified by
droplets of water evaporating from mucosal surface
 Other functions:
 detect olfactory stimuli
 Receptors located in upper part of nasal cavity in region called olfactory epithelium
 Modifies speech vibrations as they pass through sinuses – large, hollow resonating chambers of
hear
 Resonance: prolonging, amplifying, or modifying sound by vibration
The Pharynx Is a Common Passageway for Air and Food
 Pharynx: (throat) funnel-shaped tube that extends from nasal and oral cavities to larynx and esophagus
(structure plays role in digestion)
 Part of both respiratory & digestive systems
 Function: passageway for air and food & acts as resonating chamber for speech sounds
The larynx Routes Air and Food into the Proper Channels and Also Causes Vocalization
 Larynx: (voice box) show passageway that connects pharynx w/ trachea
 Thyroid cartilage or Adam’s apple: cartilage protrusion located in anterior neck
 Important function: allow air – not food or liquid – to flow into rest of airways with help of epiglottis
 When air is present: epiglottis upward position & larynx is open, allowing air to pass through
 Food/Liquid present: epiglottis moves down and forms lid over larynx, closing it off
 Other function: voice production
 Two folds of elastic tissue known as vocal cords extend from one side of larynx to other
 Air passes causing them to vibrate & produce sound waves
 Pitch controlled by tension
 Pulled taut (tight): vocal cord vibrates more rapidly & higher pitch
The Trachea Carries Air to the Primary Bronchi
 Trachea: (windpipe) tubular passageway that extends from larynx
 Purpose: convey air from larynx to primary bronchi
 Wall contains 15-20 C shaped rings of cartilage stacked
 Provides rigid structure so trachea doesn’t collage inward & obstruct airflow
The Primary Bronchi Transport Air to the Lungs
 End of trachea branches into two large bronchi
 Right primary bronchus: goes into right lungs
 Left primary bronchus: goes into left lung
 Primary bronchi contain rings of cartilage that provide support
 Function: convey air from trachea to smaller bronchi and bronchioles of lungs
The Lungs Contain Most of the Components of the Respiratory System
 Lungs: paired cone-shaped organs in the thoracic cavity
 Enclosed by double-layered membrane of epithelium and connective tissue called pleura
 Parietal pleura: outer layer that lines the walls of the thoracic cavity
 Visceral pleura: inner layer that covers the lungs
 Pleural cavity: space b/w the inner and outer layer which contains millimeters of lubricating fluid
secreted by membranes

,  Intrapleural fluid: reduces friction b/w membranes, allowing them to slide easily over one
another during breathing
 Causes two membranes to adhere to one another
 Pleurisy: inflammation of pleural membranes causes pain due to friction b/w layers
 Excess fluid accumulates in the pleural space known as pleural effusion
 Contains all branches of primary bronchus
 Entering lung: primary bronchi divide to form smaller bronchi – secondary bronchi
 One for each lobe of lung: right (3) & left (2)
 Secondary bronchi  forms smaller bronchi – tertiary bronchi  divides until bronchioles form
 Bronchioles branch into terminal bronchioles  subdivide into respiratory bronchioles ( have
alveoli extending from wall)
 Respiratory bronchioles subdivide into alveolar ducts (contains more alveoli) when penetrated
deeply into lungs
 Ducts give rise to alveolar sacs (contain large numbers of alveoli arranged in clusters)
 Helps give surface area of gas exchange
 Extensive branching from trachea referred as bronchial tree
 Larger bronchi consist: outer layer of cartilage plates, middle layer of smooth muscle, & inner layer of
mucous membrane (mucosa)
 Changes occur in layers as branching becomes more extensive
 Plates becomes less abundant & finally disappear
 Amount of cartilage decreases  smooth muscle increases; smooth encircles lumen in spiral
bands
 Mucosa changes from ciliated epithelium, w/ goblet cells in larger bronchi and bronchioles 
nonciliated epithelium, w/ no goblet cells in terminal bronchioles
 Regions w/out cilia: macrophages move inhaled particles
 Lack of cartilage and presence of smooth muscle allows tubes to change diameters & altering flow
of air to alveoli
 Bronchioles main site of resistance to air flow
 Bronchiolar smooth muscle innervated by sympathetic & parasympathetic divisions of ANS
 During exercise: norepinephrine releases from sympathetic neurons
 During relaxation: epinephrine/norepinephrine secreted from adrenal medulla bind to ß2-
adrenergic receptors which dilates bronchioles (bronchodilation)
 During rest: ACh released from parasympathetic neurons & binds to muscarinic ACh
receptors which causes constriction of bronchioles (bronchoconstriction)
 B/c less air reaches alveoli: lung ventilation decreases
 Mediators of allergic reactions (histamine) promote bronchoconstriction
The Alveoli Are the Sites of Gas Exchange Between Air and Blood
 Alveoli: air-filled sacs that extend from respiratory bronchioles, alveolar ducts, and alveolar sacs
 Consists: epithelium supported by basement membrane (sheet of extracellular material)  thinness is
vital for gas exchange
 Consists of two types of cells
 Type I alveolar cells: continuous lining of the alveolar wall & main sites of gas exchange
 Type II alveolar cells: (septal cells) secrete alveolar fluid which keeps surface b/w cells & air
moist
 Alveolar fluid includes surfactant – complex mixture of lipids & proteins
 Lowers surface tension of alveolar fluid, reducing tendency of alveoli to collapse
 Associated w/ epithelium: alveolar macrophages