Respiratory System Flashcards
Pulmonary ventilation
Breathing of air in and out of lungs
External respiration
O2 and CO2 exchange between lungs and blood
Internal respiration
O2 and CO2 exchange between systemic blood vessels and tissues
Respiratory zone
-Around 3 liters
-Site of gas exchange
-Microscopic structures: respiratory bronchioles, alveolar ducts, and alveoli
Conducting zone
-Around 150 mLs
-Conducts air to gas exchange sites
-Includes all other respiratory structures
-Humidifies, cleanses, and warms incoming air
-Dehumidifies air leaving to reclaim heat
Upper airways
Head & Neck
Respiratory tract
Larynx and Lungs
Functions of nose
-Entry/Exit airway
-Moistens and warms air
-Filters and cleans inspired air
-Chamber to resonate speech
-Olfactory receptors
Olfactory mucosa cells
Produced by olfactory epithelium & underlying CT
Respiratory mucosa cells
-Pseudostratified ciliated columnar epithelium
-Mucous and serous secretions
-Inspired air warmed by capillaries and veins
Nasal conchae
-Contains a superior, middle, and inferior region
-Protrudes medially from lateral wall
-Increases mucosal area
-Enhances air turbulence
Role of conchae and nasal mucosa during inhalation and exhalation
Inhalation: Filter, heat, and moistens air
Exhalation: Reclaims heat and moisture
Paranasal sinuses
-Cavities located in frontal, sphenoid, ethmoid, and maxillary bones
-Lightens skull, resonates sound, secretes mucus, and helps warm and moisten air
Pharynx
Muscular passage connecting nasal cavity to larynx
Three regions of pharynx
-Nasopharynx: Superior region behind nasal cavity
-Oropharynx: Middle region behind mouth
-Laryngopharynx: Inferior region attached to larynx
Role & characteristics of larynx
-Plays a role in speech
-Routes air and food into proper channel
-Sections of rigid hyaline cartilages and a spoon-shaped flap of elastic cartilage
Epiglottis
Routes food to esophagus and air towards trachea
Laryngeal prominence
Thyroid cartilage (Adams apple)
Vocal folds
Vibrate with expelled air to create sound/speech
Vestibular fold
False vocal cord
Glottis
Opening between vocal cords
Trachea
-Four inch long tube
-Walls reinforced with C-shaped hyaline cartilage
-Lined with pseudostratified ciliated columnar epithlium
-Ends of cartilage connected by trachealis muscle
-Anterior to esophagus
Divisions/Lobes of lungs
-Left lungs: Inferior and superior lobes
-Right lung: Inferior, middle and superior lobes
Types of bronchi
-Primary bronchi
-Secondary bronchi
-Tertiary bronchi
-Bronchioles
-Terminal bronchioles
-Respiratory bronchioles (No reinforced cartilage on walls)
Alveoli
-Site of gas exchange (300 million/lung)
-Rich blood supply with capillary sheets formed over alveoli
-Contain alveolar macrophages
Type I alveoli cells
-Makeup wall of alveoli
-Single layer squamous epithelial cells
Type II alveolar epithelial cells
Secrete surfactant
Surface tension
-Decreases surface area at the interface
-Attracts liquid molecules to one another at gas-liquid interface
Lung expansion via pleura
Lungs are functionally connected to chest wall by the pleural sac to allow expansion of lungs with chest expansion
Surfactant
Lipid and protein complex produced by Type II alveolar cells
-Reduced surface tension of alveolar fluid and discourages alveolar collapse
Pressure gradients and breathing
Change in pressure is the inverse of change in volume
-ΔP=1/ΔV
Negative intrapleural pressure
Causes lungs to expand to increase volume of lungs to reduce negative pressure
Pressure before inspiration
-P(atm) & P(alv) are equal around 760 mmHg
-P(intrapleural) must be lower to keep alveoli slightly open
Pressure during inspiration
-P(Alv) is lower than P(atm) causing influx of air into the lung due to diaphragm contraction
-Occurs until both values become equal
Ptp Gradient
Gradient between P(alv) and P(ip) that is always contant to prevent lung collapse
Pressure during expiration
-P(atm) is lower than P(alv) causing efflux of air from diaphragm relaxation.
Intrapleural pressure chracteristics
Remains lower than alveolar pressure throughout the respiratory cycle
Tidal volume (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 a normal tidal volume inspiration
Expiratory reserve volume (ERV)
Amount of air that can be forcefully exhaled after a normal tidal volume expiration
Residual volume (RV)
Amount of air remaining in lung after a forced expiration
Inspiratory capacity (IC)
-IC=TV + IRV
-Maximum volume inspiration after expiration quiet breath
Functional Residual Capacity (FRC)
-FRC=ERV+RV
-Amount of air in lungs after normal breath out
Vital capacity (VC)
-VC=TV+IRV+ERV
-Total amount of exchangeable air
Total lung capacity (TLC)
-TLC=TV+IRVERV+RV
-Max amount of air that could be in lungs
Lung compliance
-Stretchability of lungs
-CL=Volume of lungs /(Palv-Pip)
-Greater CL –> easier to expand lung
-Determined by elastic tissue of lung and surface tension generated at the air-water interfaces within alveoli
Pneumothorax
-Presence of air in pleural cavity –> Pip=Patm
-Causes a collapse in lung
Impact of surfactant on lung compliance
Reduced
Elastic recoil/Elastance
Elasticity of the lung, inverse of compliance, increases Pip
Law of Laplace
P=2T/r
-Without surfactant surface tension (T) increases with smaller alveolar volume
-With surfactant: Equilibrates alveoli sizes, homogenous distribution of air in different sized alveoli & prevents alveolar collapse
Causes of low compliance
-Low muscle contraction of respiratory muscles
-High surface tension (low surfactant)
-Scar tissue (Fibrosis)
-Edema (Fluid in IS space)
Causes for types of lung collapse
-Immediate: Trauma or surgery
-Overtime: Disease or tension pneumothorax
Causes of high compliance
-Emphysema: Air filled enlargment of tissue by breakdown of wall of alveoli
Ventilation
Tidal volume (TV) * Rate (f)
Treatment
Chest tube is placed in the pleural cavity, plugged into vacuum
Airway resistance
Resistance to airflow
-F=(Patm-Palv)/R
-Air flow (F) depends upon the driving pressure (P) and the resistance (R)
Determinants of airway resistance values
-Highest resistance in upper respiratory tract, trachea, and bronchi
-Lung volume determines airway lumen
-Elastic recoil determines intrapleural pressure, airway diameter
-Airway radius changes with smooth muscle or obstruction
Impact of nervous system on airway resistance
-PSNS: Smooth muscle contraction of bronchi –> asthma
-SyNS: Smooth muscle relaxation –> asthma treatment
Alveolar dead spsace
Non-functional alveoli due to collapse or obstruction or no perfusion
-Negligible in healthy lungs
Anatomical dead space
-No contribution to gas exchange
Total dead space/Physiological dead space
Sum of anatomical and alveolar dead space
Minute ventilation (VE)
-ml/min
-VE=TV*f
-f=ventilation rate(Breaths/min)
Alveolar vent (VA)
-mL/min
-VA=(TV-DV) * f
-f=ventilation rate (Breaths/min)
-DV=dead volume (mL)
-Determines efficiency of ventilation
Gas exchange
-O2 and CO2 move down partial pressure gradients by simple passive diffusion
-Gases dissolved in fluids also exert partial pressure. The greater the partial pressure of gas in fluid, the more gas is dissolved.
Instances when diffusion of gas will increase
-ΔP increases therefore P(alv) vs. P(pc)
-Membrane permeability to gas increases
-Increase in surface area of diffusion
-Decrease in membrane thickness
Ventilation (V)
Amount of gas reaching the alveoli
Perfusion (Q)
Amount of blood flow reaching alveoli
Pressure Gradients & Gas Exchange principles
-Amount of O2 picked up in lungs matches the amount extracted and used up by tissues
Mixed venous pressure/Pmv(O2)
Immediately available O2 reserve for increased demand
Means of compensation
- Recruitment of other capillary beds within the lung
- Distension of small vessels
Methods of O2 transport in blood
-Physically dissolved: 1.5%
-Bound to Hgb: 98.5%
Methods of CO2 transport
-Physically dissolved: 10%
-Bound to Hb: 20%
-As bicarbonate: 70%
Carbonic anhydrase
Converts CO2 and water into carbonic acid (Bicarbonate & proton)
Chloride shift
Bicarbonate acid exits RBC (For CO2 transport) in exchange for CL- ions from plasma in order to maintain a concentration of ions that endusres electrical neutrality
Left shift on binding curve
-Increase affinity for O2
-Decrease CO2 pressure
-Decrease in [H+], Increased pH
-Decrease in BPG
-Decrease in temp
Right shift on binding curve
-Decreased affinity for O2
-Increased CO2 pressure
-High [H+], Decreased pH
-Increase BPG concentration
-Increase in temp
Control of respiration
-No pacemaker activity in lungs or respiratory muscles
-Respiratory centers located in medulla oblongata
-Maintains homeostasis of O2, CO2, and pH
-Impacts rate (f) and depth (TV) of respiration
Regulation of magnitude of ventilation
-Located in pons center in pneumotaxic and apneustic centers
-Response to strenous exercise: Increase in TV & pulmonary stretch receptors preventing overinflation
-Used to modify respiratory activity for speech, singing, coughing, and sneezing
Neural ventilation control receptors
-Neurons in the reticular formation of medulla oblongata and pons
-Requires input from chemoreceptors, mechanoreceptors, cerebral cortex, and hypothalamus
