Chapter 22 Respiratory System Flashcards
Major Functions of Respritory System
- Major Function
- Supply O2 for cellular respiration
- dispose of CO2
- Done through the process of Respriation
- Also functions in olfaction and speech
Process’ of Respriation
- Respritory system
-
Pulmonary Ventilation (Breathing)
- movment of air into and out of lungs
-
External respriation
- O2 and CO2 exchange between lungs and blood
- Circulitory System
-
Transport
- O2 and Co2 in blood
- Internal Respriation
- O2 and CO2 echange between systemic blood vessels and tissues
Functional Anatomy
- upper respritory system) consists of structures from the nose to larynx
- lower respritory sytem) consists of the larynx and all the structures below it
The Nose
- Functions
- Airway for respriation
- warms entering air
- Filters and cleans air
- Resonating chamber for Speech
- Smell
- External Nose
- Root (area between eyebrows)
- Bridge) dorsum nasi
- Apex (top of nose)
- Nostrils are surrounded by alae
Internal Nasal Cavity
- Cavity that lies in and posterior to external nose
- Divided by Nasal Septum (midline)
- Posterior Nasal apatures) continious with nasal canal
- Roof) Ethmoid and Sephnoid bones
- Floor) formed by the palate
- Nasal Vestibule) superior to the nostrils
- Vibriasse (hairs) folter coarse particles
- Olfactory Mucose) Contains Smell receptors
- lies in olfactory epitheliam
- Respritory mucose) lines most of the nasal cavity
- Psuedostratifued ciliated columnar epitheliam with goblet cells
- secrete lysozyme and defensisns
- Cillia moves mucas to throat
- Nasal Chonche) increase air turbulance
- nasal meatus) grove inferior to conche
- Paranasal Sinuses
- Lighthen skull/ warm air
- Functions of Nasal Mucosa and Chonche
- Filter and heat air during inhalation
- Reclaim heat and moisture during exhlation
Rhinitis
- inflmation of nasal mucosa with excessive mucus production
- caused by cold virusus, bacteria and various allergens
- Nasal mucosa continuious with mucousa of respritory tract
- Spreads From Nose > Throat> Chest
- Sinisitus) when rhinitis spreads to paranasal sinuses
- Sinus Headahe) Mucus/ infectious material blocks sinus passageways to nasal cavity creating pressure.
Pharynx
- Muscular Tube from Skull to C6
- connects nasal cavity/ mouth to larynx and esophagus
- composed of skeletal muscle
- Three regions
- Nasopharynx. Oropharynx, Laryngopharynx
Nasopharynx
- AIR passageway posterior to the nasal cavity
- Lined by psudostratified columnar epithelium
- Soft Plalte/ Uvula close nasopharynx during swallowing.
- Pharyngeal Tonsil (Adenoids)
- Located on Posterior wall
- Traps and destroys pathogens
- Pharyngotympanic (Auditory) Tubes
- drains and equalizes pressure in middle ear; open into lateral walls of nasopharynx
- Tubal Tonsil) ridge of pharengeal mucosa that protects against ear infections
Oropharynx
- Passageway for food and air from anywhere between the soft palate and epiglottis
- Lined by Stratified Squamous Epithelium
- Isthmus of fauces (throat) opening to oral cavity
- Palentine Tonsils) In lateral walls, posterior to oral cavity
- Lingual tonsil) located on the posterior surface of the tongue
Laryngopharynx
- Passageway for food and air
- Lined with Stratified Squamous Epithelium
- Posterior to upright epiglottis, extends to larynx where it is continuious with the esophagous
Lower Respritary System
- Consists of two zones
- Respritory Zones) sites of gas exhange
- all microscopic structures (Respritory bronchioles, alveolar ducts, and alveoli
- Conducting Zones) All respiratory passageways from nose to bronchioles.
- provide conduits for air to reach gas exchange sites
- Cleanse, Warm and Humidifys air
Larynx (Voice Box)
- Attaches to the hyoid bone superiorly
- opens into the laryngopharynx
- Continuous with trachea
- Functions
- Provides and open airway
- Routes air and food into proper channels
- Voice Production) Houses vocal folds
- Framwork of Larynx is arrangment of nine cartliges (Hayline cartlidge)
- Thyroid Cartlidge with Larengal prominence (Adams apple)
- Ring Shaped Circoid Cartlidge
- Paired, Artenoid, Cuniform, and Corniculate Cartlidges
- Arytenoid holds vocal folds
- Epigliottis) ninth cartlidge made of elastic cartlidge
- covers laryngeal inlet during swallowing
- Initiates cough reflex to expel the substance.
- Covered with taste-bud containing mucosa
Vocal Ligaments
- Deep to laryngeal mucosa on each side
- composed largley of elastic fibers
- Attach artenoid cartlidge to thyroid cartlidge
- Form core of Vocal folds (true vocal chords) which lack blood vessels
- Glottis) opening between vocal folds
- Folds vibrate to produce sound as air rushes from the lung
- Vestibular Folds (False Vocal Cords)
- superior to vocal folds
- No part in sound production
- Help to close glottis during swallowing
Epihtelium of Larynx
- Superior Portion) Stratified Squamois Epithelium
- Inferior Vocal Folds) Pseudostratified ciliated columnar epithelium
Voice Production
- Speech Involves release of air while opening/closing glottis
- Pitch) Determined by length/tension of vocal chords
- Tenser chords = Faster Vibration =Higher Pitch
- Boys larynx’s enlarge during puberty and their voice becomes deeper
- Loundness) Depends upon force of the air
- Yelling is louder than wispering
- Chambers of pharynx, oral, nasal, and sinus cavities amplify and enhounce sound quality
- Sound is “shaped” into language by muscles of pharynx, tounge, soft palate and lips.
Sphincter Functions of Larynx
- Vocal Folds may act as a sphincter to prevent air passage
- Vasalva’s manuever (Occurs during abdominal strain accociated shitting)
- Glottis Closes to prevent exhalation
- Abdominal muscles contract
- Intra-Abdominal pressure rises
- Helps to empty rectum or stabilize trunk durign heavy lifitng
Trachea (windpipe)
- From Larynx into Mediastium
- Wall composef of three layes plus a layer of hyaline cartlidge
- Mucose) cilliated psudostratified epithelium with goblet cells
- Submucosa) CT with seromucous glands that help produce mucus
- Adventitia) Submucosa is supported by 16-20 C shaped rings of Hylane cartlidge encased by Adventitia
- Trachealis Muscle) Connects Posterior Parts of Cartilage rings.
- allows flexibality for food and air to pass
- Carina) Where trachea branches into two main bronchi
Bronchi and Subdivisions
- Bonchial Tree > Conducting Zone Structures > Respritory Zone Structures
- Conducting Zone Structures
- Trachea > Right or Left main (primary) bronchi
- Each main bronchus enters hilum of one lung
- Right bronchus wider, shorter and more vertical than the left
- Main bronchi branches into Lobar (secondary) bronchi
- Three on the right, two on the left
- Each lobar bronchus supplies one lobe
- Lobar bronchus branches into Segmental (tertiary) bronchi, Which divide repeateadly
- Branches become smaller and smaller
- Bronchioles) less than 1 mm in diameter
- Terminal Bronchiles) smallest less than .5 mm
Conducting Zone Structural Changes
- Support Structures Change
- Carlige rings become irregular plates
- In Bronchiles elastic Fibers relace cartlidge
- Epthelium Type Change
- Epithelium Changes from psuedostratified columnar to simple columnar then to simple cuboidal in terminal bronchiles
- Amount of Smooth Muscle Increases
- Allows Constriction
Respritory Zone Structures
- Begins as Terminal Bronchioles > Respritory bronchioles > aveolar ducts > alveolar sacs > alveolar saccules
- Avelolar sacs contain clusters of alvoli
- 300 million make up most of lung volume
- sites of gas exchange
Respritory Membrane
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Alveoli
- Three major types of cells are found in alveoli
- Single layer of squamous epithelium (type 1 alveolar cells) form alveolar wall/basment membrane
- Cuboidal Type II Alveolar Cells) secrete surfacent/ antimucrobial proteins
- Alveolar Macrophages) Keep alveolar surfaces sterile
- Surrounded by same fine elastic fibers that surround entire bronchial tree
- Open alveolar pores connect adjacent alveoli
- equalizes air pressure throuought lung and provides alternate routes to diffrent alveoli.
Lungs
- Surrounded by Plurae and connected to mediastium by vascular and bronchial attachments, called the root.
- Anatomy
- Costal Surface) Sides of lungs, Anterior, Posterior
- Apex) Tip; deep to the clavicle
- Base) Inferior surface; rests on diaphragm
- Hilum) Site of entry/exit for blood vessls, bronchi, lymphatic vessels, and nerves
- Stroma) Mostly elastic CT
- Left Lung) Smaller than the right
- cardiac notch) Concavity for heart
- Oblique Fissure) Seperates superior and inferior LOBES
- Right Lung) Larger
- Horizontal and Oblique Fisures seperate the Superior, Middle, and Inferior lobes
- Each Lobes contains a number of pyrmaid-shaped Bronchopulmonary Segments (10 on the right, 8-10 on the left)
- Lobules) smallest divisons vivible to the naked eye
- appear as hexagons
Blood Suply to the Lungs
- Pulmonary Circulation (low pressure, high volume)
- Pulmonary arteries) deliver venous blood for oxignation to pulmonary capilary networks
- Pulmonary Veins) carry oxygnated blood from respiratory zones to the heart.
- Bronchial Circularion (high pressure, low volume)
- Bronchial Arteries) Provide oxygnated systemic blood to lung tissues
- Arise from aorta and enter lungs at hilum
- Provide blood supply to all lung tissues except alveoli.
Pleurae
- Thin, double-layered serosa
- Divides thoracic cavity into two compartments and mediastium
- Parietal Pleura) On thoracic wall, superior face of the diaphragm, around the heart, between lungs
- Visceral Pleura) on external lung surface
- Pleural Fluid) fills pleural cavity. Lubricates lungs
Air Movment in Lungs
- Volume changes cause pressure changes which casues air to move
- Inspiration) gasses flow into lungs
- Expiration) gasses exit lungs
Pressure Relationships in Thoracic Cavity
- Atmospheric Pressure (Patm)
- Pressure exeted by air surrounding body
- 760 mmHg = 1atm
- Intrapulmonaty Pressure (intra-alveolar) (Ppul)
- Pressure in alveoli
- Fluctuates with brething
- Eventually equals Patm
- IntraPleural Pressure (Pip)
- Pressre in pleural cavity
- Fluctuates with breathing
- always less than Patm and Ppul
- Fluid level must be minimal; pumped out by lymphatics
- If accumulates > Positive Pip pressure > lungs collapse
- Pressures described compared to Patm
- =
- Negative Pressure in Pleural space caused by
- Elastic recoil of lungs pulling on plueral space
- Surface tenion of alveolar fluid reduces alveolar size
Pressure Relationships
- Transpulmonary pressure
- diffrence between intrapulmonary and intraplerual pressures
- Ppul-Pip
- Keeps airway open
- Greater Transpulmonary Pressre= Larger lungs
Pulmonary Ventilation
- Mechanical Processes that depend on volume changes in thoracic cavity
- Volume Changes> Pressure changes
- Gasses flow to equalize pressure
- Boyles law) Shows relationship of pressre anf volume of gas at a constant tempratue
- P1V1=P2V2
Inspiration
- Active Processes
- Inspiratory Muscles (Diaphragm moves inferiorly, External intercostals contact to lift rib cage)
- Thoracic Volume Increases> Interpulmonary pressure drops (-1mmHg) and becomes less than the atmospheric pressure.
- Lungs Streatched = More Volume = Airflow into lungs to compensate
- Forced Inspiration
- Occurs during vigourous excercise and in chronic obstructive pulmoanry diseases
- Involves accesory mucles (Scalenes, Sternoclidomastoid muscles, Pec minor)
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Expiration
- Quiet Expiration
- passive provess
- Inspiratory mucles relax = thoracic volume decreases
- Ppul rises to +1mmMG, air flows out
- When Ppul > Patm the pressure gradient forces gases out of the lungs
- Forced Expiration
- Avtive Process
- Uses abdominal mucles
Airway Resistance
- Friction) Major noneslatic source of resistance to gas flow; occurs in airways
- Relationship between Flow (F), pressiure (P), and resistance (R) is
- F= Change P/ R
- Change P= Pressure gradient between atmosphere and alveoli
- Airway resistance is normaly insigifigant
- Large in diameter
- Gets more resistant as the branches get smaller
- Greatest resitance in Medium-Sized Bronchi
Resistance Homeostatic Imbalance
- Airway Reistance rises= more strenous breathing
- Severe constriction or obstruction of the bronchiles
- can prevent ventilation
- can occur during asthma attacks
- Epinephrine dilates bronchioles, reduces air resistance
Alveolar Surface Tension
- Surface tension
- Attracts liquid molecules to one anohter at gas-liquid interface
- Resists any force that tends to increase surface area of liquid
- Water has a high surface tension; coats alveolar walls
- Surfactant
- Detergent-like lipid and protein complex produced by type II alveolar cells
- Reduces surface tension of alveolar fluid/ discourages alveolar collapse
- Infant respiritory Distress syndrome) caused by an insufficent quantity
Lung Compliance
- Lung compliance) the ability of a healthy lung to streatch
- It is a measure of change in lung volume that occurs with a given change in transpumonary pressure
- Δ CL= Δ VL / (Ppul – Pip)
- Higher Lung Compliencee = Easier to expane
- Depends on two factors
- Disstenisibility of lung tissue
- Alveolar Surface Tension
- Diminished by
- Chronic Inflimation or Infection
- Fibrosis) Nonelastic scar tissue replaces lung tissue
- Reduced production of sufactant
- Decreased flexability of thoracic cage
- The total compliance of the respiratory system is comprised of lung compliance and thoracic wall compliance.
Respriritory Volumes
- Tidal Volumes (TV) Amount of air inhaled or exhaled with each breath under resting conditions
- Inspiratory Reserve Volume (IRV) Amount of air that can be forcefully inhaled after normal tidal inspiration
- Expriatory Reserve Volume (ERV) ammount of air that can be forcefully exhaled after normal tidal expiration
- Redidual Volume (RV) Ammount of air remaining in lungs after a forced expiration
Respritory Capicaties
- Inspiratory capacity (IC): Maximum amount of air thatcan be inspired after a normal tidal volume expiration
- IC = TV + IRV
- Functional residual capacity (FRC): Volume of air remaining in the lungs after a normal tidal volume expiration
- FRC = ERV + RV
- Vital capacity (VC): Maximum amount of air that can be expired after a maximum inspiratory effort
- VC = TV+ IRV + ERV
- Total lung capacity (TLC): Maximum amount of air contained in lungs after a maximum inspiratory effort
- TLC = TV + IRV + ERV + RV
Dead Space
- Anatomical Dead Space
- Some conducting respritory passgeways never contribute to gas exchange in alveoili
- Air remaining in passageways about 1ml per pound of body weight
- Alveolar Dead Space
- Non-Functional Alveoli due to collapse or obstruction
- added to anatomical dead space
- Total Dead Space
- Sum of all dead space
Pulmnonary Function Tests
- Spirometery) Most useful for evaluating loss in fucntion for following desieses and for respritory volume and capacities
- Obstructive pulmonary desiese) increased air way resistance (Total lung capicity {TLC}, Functional Residual Capicity {FRC), and RV may increase)
- Restrictive Disorders) Reduced TLC, (VC vital capicity, TLC, FRC, and RV decline)
- Forced Vital Capicity (FVC) Measures ammount of gas expelled after deep breath
- Forced Expiratory Volume (FEV) amount of gas expelled during specific time intervals of FVC test
- Those with healty lungs can exhale 80% of FVC within one second
Alveolar Ventilation
- Dead space is normally constant
- Rapid, shallow breathing decreases AVR
Nonrespritory Air Movments
- May modify normal respiratory rhythm
- Most result from a reflex action (some voluntray)
- ex) cough, sneeze, crying, laughing, hiccups, and yawns
Dalton’s Law of Partial Pressures
Henry’s Law
Composition of Alveolar Gas
- Alveoli contain more CO2 and water vapor than atmospheric air and much less O2
- Diffrences reflect the effects of
- gas exchange in the lungs
- Humidification of air by conducting passages
- Mixing of new and old alveolar gasses with each breath
External Respiration
- Exchange of O2 and CO2 across respiratory membrane
- Influenced by
- Thickness and surface area of respirtory membranes. 0.5-1 nanometer thick and gigantic surface area
- Partial Presssure Gradients and Gas Solubilities. Drives O2 into venous blood and pulls CO2 out of venous blood
- Ventilation- Perfusion Copling) adaquete blood flow reaches the alveoli (perfusion) and gas reaching alveoli (ventilation)
- Ventilation-Perfusion Coupling
- Influence of local Po2 on perfusion.
- O2 high = arteioles dilate
- O2 low = Arterioles constrict and redirect to high
- Influence of Local PCO2
- CO2 high= Bonioles dialate to eliminate faster
- CO2 Low = Broncioles constrict
Internal Respiration
- Gas exhange in body tissues (capillary)
- Partial pressure and diffusion gradients reversed
- systemic O2 is lower than blood O2
- CO2 moves from tissues to blood.
O2 Transport in Blood
- O2 Transport
- molecular O2 carried in blood by hemoglobin in RBC’s (main conetent) and some in plasma
- Oxyhemoglobin) oxygnated hemoglobin
- Deoxyhemoglobin) no O2
- Loading/ unloading of O2 causes a change in the shape of Hb
- O2 binds, Hb affinity for O2 increases
- O2 released, Hb affinity for O2 decreases
- Rate of O2 loading/ unloading is influenced by
- PO2, Temp, Blood PH, PCO2, and concentration of BPG
Influence of O2 on hemoglobin saturation
- In arterial blood.
- PO2 = 100 mm Hg
- Contains 20 ml oxygen per 100 ml blood. (20% of volume)
- Hb is 98% saturated
- Further increases in O2 does not increase saturation
- In Venous blood
- 15% volume is O2
- Hb is 75% saturated
- Venous reserve) substancial ammounts of O2 are aviable in venous blood if need be.
- Temprature
- Increase in Temp = lower affinity for hemoglobin absorbtion
- Decrease in Temp = Higher affinity for hemoglobin absorption
- BPG (2,3-bisphosphoglycerate)
- reversibly binds with hemoglobin, levels rise when oxygen levels are chronically lwo
CO2 Transport
- Transported in Three forms
- 7-10% dissolved in plasma
- 20% bound to globin of hemoglobin
- does not interfere with O2 transport
- Deoxygnated Hb combines faster with CO2 than oxygnated Hb does
- 70% transported as Bicarbonate ions (HCO3-) in the plasma
- Carbonic Acid (CO2 + H20 <> H2CO3 <> H+ + HCO3-
- carbonic anhydrase
- Systemic Caplilaries) HCO3 quickley diffueses from RBC’s into plasma
- Chloride Shift) outrush of HCO3-
- Pulmonary Capillaries
- HCO3- moves into RBCs
Haldane Effect
- Lower PO2 and hemoglobin saturation = More CO2 carried in blood
- reflects greater ability of reduced Hb to form carbaminohemoglobin
- More CO2 enters blood = More O2 Dissociates from Hemoglobin
- Bicarbonate Buffer System) Reists changes in blood pH
Hypoxia
- Inadequate O2 delivery to the tissues > Leads to cyanosis
- Anemic Hypoxia) Too few RBC’s / Hb
- Ischemic Hypoxia) Impaired circulation
- Histotoxic Hypoxia) Cells unable to use O2
- Hypoxemic Hypoxia) abnormal ventilation
- Carbon monixide posioning) Binds to HB 200x better than O@
Control of Respiration
- Involves higher brain centers, chemoreceptors and other reflexes
- Neural Controls
- nuerons in medulla and pons
Breathing Rate and Depth
- Depth) determined by how activally the respritory center stimulates the resproritory muscles
- Rate) Determined by how long the inspiratory center is active
- Influence of PCO2
- blood Co2 levels rise (hypercapina) CO2 accimulates in the brain
- Carbonic acid dissociates releasing H+ to drop pH
- Chemoreceptors detect higher pH and increase respritoty rate
Hyperventilation
- Increased depth and rate of breathing that exceeds the body’s need to remove CO2
- Results in hypocapina
- Apnea) breathing cessation from Low PCO2
Influence of arterial pH
- Can modify respritory rate and rhytm even of CO2 and O2 levels are normal
- Aterial pH declines > respritory system increases rate to eliminate CO2
Influence of Higher Brain Centers
- Hypothalamic controls act through limic system to modify rate and respiration
- ex) holding breath with anger
- Raise in body temp increases respritory rate
- Cortical controls) signals that directly bypass medullary controls
Respritory Adjustments) Excercise
- Hyperpnea) increased ventilation in response to metabolic needs (10-20x larger)
- diffrent than hyperventilation (does not alter PCO2 levels)
- Three nural factors increase ventilation as excercise begins
- physcological stimuli) antipication of excercise stiumulates cortical motor activation
- Excitatory impules to respritory centers from propioceptors
Respiratory Adjustments) High Altotuide
- altuides above 2400 meters (8000 feet) may
- Lower PO2 levels
- Headaches, shortness of breath, nausea, and dizziness
- lethal cerebral and pulmonary edema in severe cases
- Acclimatization) Adustments to high altuide
- body becomes more responsive to increases in PCO2 and decline of PO@
- Ventilation Increases > Lowers PCO2
- Erythopoiten stimulates bone marrow to produce more RBC’s
Chronic Obstructive Pulmonry Diesase (COPD)
- Exemplified by chronic bronchitis and emphysems
- Irreversiable decrease in ability to force air out of the lungs
- Common Features)
- history of smoking
- Dyspnea) difficult breathing
- Coughing and frequent pulmonary incfractions
- Respritory Failure (hypoventilation)
Emphysema
- Permanent enlargement of alveoli; destruction of alveolar walls; decreased lung elasticity
Chronic Bronchitis
- Inhaled Irritanats > Chronic Prodiction of excessive mucus > Inflamed and fibrosed lower respritory pathwways > Impaired lung ventilation
- Frequent pulmonary infections
Asthma
- Characterized by coughing, dyspnea, wheezing, and chest tightness - alone or combination
- Active inflammation of airways precedes
bronchospasms - Airways thickened
- Active inflammation of airways precedes
Tuberculosis (TB)
- Infectious disease caused by Myobacterium Tuberculosos
- Symptoms) Feaver, night sweats, weight loss, racking cough, coughing up blood
- Treatment) anitbiotics
Lung Cancer
- Leading cuause of Cancer Deaths
- 90% of all cases due to smoking
- No Metastisis) surgery to remove lung tissue
- Metastisis) radiation and chemotherapy
Cystic Fibrosos
- Abnormal, Viscous mucus clogs passageways and causes infections
- Affects lungs, pancreatic ducts, and reproductive ductsz