chapter 13 the respiratory system
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Chapter 13 The Respiratory System. Biology 110 Tri-County Technical College Pendleton, SC. System Essentials. Supply cells with oxygen Pick up carbon dioxide from the body Eliminate carbon dioxide from the body - PowerPoint PPT PresentationTRANSCRIPT
Chapter 13 The Respiratory System
Biology 110
Tri-County Technical College
Pendleton, SC
System Essentials
Supply cells with oxygen
Pick up carbon dioxide from the body
Eliminate carbon dioxide from the body
Organs of respiratory system include: Nose, pharynx, larynx, trachea, bronchi and its branches, and the alveoli of the lungs
Respiratory System Visual
A nose for this…or that
Only externally visible part of systemAir enters nose through external nares (nostrils)Interior consists of nasal cavity divided by midline nasal septumOlfactory receptors in mucosa in superior part of cavity just below ethmoid bone
Nose, cont.
Rest of mucosa lining called respiratory mucosa rests on network of thin-walled veins that warms air flowing pastMucosa moistens inhaled air & traps
incoming debris
Ciliated cells move contaminated mucus posteriorly toward throat (pharynx) swallowed & digested by stomach acid
Nose, cont.Three mucosa-covered lobes called nasal conchae increase surface area exposed to air Also increase turbulence in nasal cavity
Nasal cavity separated from oral cavity by partition called the palate
Anterior palate supported by hard bone = hard palate
Posterior palate is unsupported by bone = soft palate
Paranasal SinusesNasal cavity surrounded by paranasal sinuses located in frontal, sphenoid, ethmoid, and maxillary bones Lighten the skull Resonance chambers for speech Produce mucus that drains into nasal cavity
Nasal mucosa continuous throughout RT Nasal infections can spread throughout mucosa
Sinusitis difficult to treat & can cause marked change in voice quality
Paranasal Sinuses Visual
PharynxMuscular passageway for food and air commonly called throatNaso-; Oro-; and laryngopharynxAir enters superior portion (naso) from nasal cavity anteriorlyAir descends through oropharynx and laryngopharynx to enter larynx belowFood from mouth travels with air through oro- and laryngopharynx but directed posteriorly to esophagus instead of entering larynx
Pharynx, cont.
Auditory tubes that drain middle ear open into nasopharynxotitis media (ear infection) may follow sore throat/pharyngeal infectionsClusters of lymphatic tissue called tonsils found in pharynxPharyngeal: (adenoids) located high in nasoPalatine: oropharynx at end of soft palateLingual: at base of tongue
Respiratory Visual
Larynx and Associated Structures
Larynx (voicebox) routes air/food into proper channels and plays role in speech
Formed by 8 rigid hyaline cartilages and elastic cartilage called epiglottis
Largest of hyaline cartilages is THYROID cartilage (Adam’s apple)
Epiglottis protects superior opening of larynx
Larynx, cont.
Not swallowing, epiglottis does not restrict passage of air into respiratory passages
Swallowing, larynx pulls forward and epiglottis tips forming lid over opening of larynx
Routes food/drink into esophagus posteriorly
Cough reflexunconscious person
Larynx, cont.
Part of mucous membrane of larynx forms pair of folds called vocal folds (true vocal cords) which vibrate with expelled airAllows speechSlitlike passages between folds called glottisLarynx leads to trachea (windpipe)
Trachea
Extends from larynx to level of 5th thoracic vertebra (~ midchest)
Lined with ciliated mucosa
Walls reinforced with C-shaped rings of hyaline cartilage
Open parts of rings abut esophagus and allow it to expand anteriorly when one swallows
Trachea, cont.
Solid portions support walls and keep it patent (or open) in spite of pressure changes during breathing
Tracheal obstructions are LIFE-threatening
Heimlich maneuver can unclog trachea It works or my side would be gone…for good
Sometimes emergency trachesostomy is required
Bronchi DivisionsTrachea divides into right and left primary bronchi
Each primary bronchi plunges into medial depression (the hilus-depressed area where vessels enter/leave an organ) of lung
Right pulmonary bronchus is wider, shorter, and straighter than left
Smaller subdivisons of primary bronchi within lung deliver air to alveoli
Bronchi Visual
Lungs and more…
Occupy most of thoracic cavity except for mediastinum (houses heart, great blood vessels, bronchi, esophagus, thymus, and trachea)
Narrow superior portion is APEX; located just deep to clavicle
Broad area resting on diaphragm is BASE
Each lung divided into LOBES by fissures
Left lung = 2 lobes; right lung = 3 lobes
Lungs, cont.Surface covered by visceral (pulmonary) pleura and walls of thoracic cavity lined by parietal pleura
Membranes produce pleural fluid which allows lungs to glide easily over thorax wall during breathing Also causes 2 pleural layers to cling together
Glide easily but resist being pulling apart Absolutely essential for normal breathing
Lungs, cont.
PLEURISY (inflammation of pleura) can be caused by decreased secretion of pleural fluid Surfaces become dry and roughfriction and
stabbing pain with each breath Another kind of pleurisy results in excess fluid and
pressure on the lungs
Primary bronchisecondary & tertiary bronchibronchiolesterminal bronchioles (conducing zone structures)respiratory zone structures
Lungs, cont.RZ structures include respiratory bronchiolesalveolar ductsalveolar sacsalveoli and is ONLY site of gas exchange
Exchange of GasesAlveoli composed largely of single layer of layer of squamous epithelial cells
External surface of alveoli covered with cobweb of pulmonary capillaries
Alveolar and capillary walls construct respiratory membrane (air-blood barrier)
Blood flowing on one side; air on the other
Gases diffuse across air-blood barrier by simple diffusion
Gas Exchange, cont.Surface area of lungs = size of racquetball court (70-80 sq. meters)
Macrophages (dust cells) wander in and out of alveoli to pick up bacteria/debris
Cuboidal epithelial cells scattered throughout alveolar walls secrete surfactant (lipid that coats gas-exchange alveolar surfaces and is important in lung function
Gas Exchange Visual
Events of Respiration
Pulmonary ventilation (breathing)External respiration (gas exchange between pulmonary blood and alveoli)Respiratory gas transport (gas must be transported to/from lungs and tissue cells via bloodstreamInternal respiration (gas exchange between blood and tissue cells at systemic capillaries
Mechanics of Breathing
Pulmonary ventilation depends on volume changes in thoracic cavityVolume changes lead to pressure changes flow of gases to equalize the pressureGas always fills its container Volume of container related to pressure of gas
Inspiration = gas flowing into lungsExpiration = gas flowing out of lungs
Mechanics of Inspiration
Diaphragm & external intercostal muscles contractSize of thorax increaseslungs adhere tightly to thorax wallsstretched to new, larger size of thoraxLung volume increases producing partial vacuum (pressure less than atmospheric pressure) Air rushes in to fill space—inspiration is always an active process
Mechanics Visual
Mechanics of Expiration
Usually passive process that essentially reverse of inspirationActive expiration (forced)—internal intercostals activated and contracted to depress rib cage and abdominal muscles contract to help FORCE air from lungsAsthma (spasms of bronchioles) or chronic
bronchitis/pneumonia can narrow respiratory passageways
Mechanics, cont.
Actelectasis (lung collapse) renders lung useless for ventilationair enters pleural space through chest
wound or rupture of visceral pleural (allows air to enter pleural space from respiratory tract)
Pneumothorax is term given presence of air in intrapleural space (disrupts fluid bond between pleura)
Mechanics, cont.
RESPIRATORY SOUNDS:Bronchial sounds produced by air rushing through large respiratory passageways such as trachea and bronchiVesicular breathing sounds occur as air fills alveoliSoft and resemble muffled breeze
Modified Respiratory Movements
Situations other than breathing move air in and out of respiratory system
Most “nonrespiratory air movements” are result of reflex activity
Cough, sneeze, crying, laughing, hiccups, yawn, sighing….
External Respiration
Actual exchange of gases between alveoli and blood (pulmonary gas exchange)Oxygen leaves alveolus and enters blood capillaryCarbon dioxide leaves blood capillary and enters alveolusOccurs by simple diffusion (movement occurs toward area of lower [ ] of diffusing substance)
Gas TransportVery small amount of O2 dissolved in bloodMost transported as oxyhemoglobin Hb + O2 HbO2
Most CO2 transported as bicarbonate ion 20-30% carried inside RBCs bound to hemoglobin (at different site than oxygen)Very small amount transported in plasma
CO2 + H2OH2CO3H+ + HCO3-
For carbon dioxide to diffuse out of blood into alveoli, reaction must be reversed
Gas Exchange Visual
Internal Respiration
Gas exchange process that occurs between systemic capillaries and tissue cellsCarbon dioxide leaves tissues and enters bloodOxygen leaves blood and enters tissuesAll gas exchanges made according to the laws of diffusion
Respiration ControlsActivity of respiratory muscles, diaphragm, and external intercostals regulated by brain impulses carried by phrenic and intercostal nervesRespiratory rhythm and depth control center located in medulla and ponsMedulla contains self-exciting inspiratory and expiratory centers Sets the rhythm of breathing
Controls, cont.Pons contains apneustic and pneumotaxic centers Smooth out basic rhythms of inspiration and expiration
Work to maintain ~ 12-15 respirations/min.EUPNEA= normal breathing rateInspiratory center active = inspireExpiratory center active = expireApneustic center in pons=keeps inspiratory center goingPneumontaxic center in pons=limits length of inspiration and promotes expiration
Rate/Depth Breathing FactorsPHYSICAL such as walking, coughing, and exercise >body temp can > rate of breathing
CONSCIOUS such as singing, swallowing, or holding breath while swimming voluntary control limited then involuntary takes
over
EMOTIONAL such as fright, surprise, or “other”
Factors, cont.CHEMICAL most important rate and depth factors CO2 and O2 levels in blood
Increased levels of CO2 and decreased blood pH MOST important stimuli leading to increase in rate/depth of breathing
Changes in CO2 [ ] in blood act directly on medulla centers
Changes in O2 [ ] in blood detected by chemoreceptors in AORTIC ARCH and CAROTID body in carotid artery
Factors, cont.Chemoreceptors send impulses to medulla when blood O2 levels are dropping
<s in O2 levels ONLY important when they are dangerously LOW Increases rate/depth of breathing
Hypoventilation=accumulation of CO2 in blood and >ed blood acidity
Hyperventilation=CO2 removed from blood and <ed blood acidityAcidosis or alkalosis can result
Respiratory Related TermsApena is cessation of breathing caused by hyperventilationDyspnea is labored or difficult breathingEmphysema=alveoli enlarge as walls of adjacent chambers break through; chronic inflammation promotes fibrosis of lungs Requires lots of energy to exhale
Chronic bronchitis=mucosa of lower respiratory passages become severely inflamed and produces extra mucus
Terms, cont.
Chronic bronchitis impairs ventilation and gas exchange and increases risk of lung infections
Pneumonitis=inflammation of alveoli of the lungs resulting in them becoming clogged with mucus and/or fluids
Volumes and CapacitiesTidal volume (TV) is amount of air moved in and out of lungs with each breath (500 ml)Inspiratory Reserve Volume (IRV) is amount of air that can be forcibly taken in over tidal volume (2100-3200 ml)Expiratory Reserve Volume (ERV) is amount of air that can be forcibly exhaled after tidal expiration (1200 ml)
Volumes, cont.
Residual Volume (RV) is amount of air left in lungs that cannot be voluntarily expelled
Vital Capacity (VC) is sum of TV + IRV + ERV Total amount of exchangeable air about 4800 ml in healthy young males
Dead space volume is air that remains in conducting zone
Volume Visual