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exchange of gases
major function of the respiratory system
by altering circulating CO2 levels
how does the respirtory system regulate pH?
heat and water loss
challenges of the respirtory system
regulation of pH, protection from inhaled pathogens, vocalization
other respiratory system functions
muscular pump
generates pressure gradients in the respiratory system
muscles that move the thoracic cavity
what makes up the respiratory pump?
pressure gradients
what drives the flow of air into and out of the lungs?
diameter of airways
what determines the resistance in the respiratory system?
external respiration
exchange of gases between atmosphere (atm) and blood
ventilation
exchange b/w atmosphere and lungs
inspiration
drawing air into lungs
expiration
pushing air out of lungs
mouth, nasal cavity, pharynx, larynx
what makes up the upper respiratory tract?
trachea, primary bronchi, bronchial tree
what makes up the lower respiratory tract?
alveoli
functional units for gas exchange
musculoskeletal pump
bones and muscles of the thoracic cavity
airways
air conducting system
pulmonary and cardiovascular systems
what components are involved in respiration?
spine, ribcage, chest wall
bones that play a role in ventilation
move bones and alter thoracic volume
role of muscles in respiration
diaphragm
forms floor, dome shaped muscle in relaxed state
intercostal muscles
muscles located between ribs
internal
which intercostal muscles cause expiration
external
which intercostal muscles cause inspiration
scalenes
move the 1st rib
pleural membrane
double membrane that surrounds lungs
parietal pleura
portion of pleural membrane adherent to thoracic wall
pleural space
filled with small amount of pleural fluid; eases movement of pleural
membrane as lungs expand, recoil
visceral pleura
portion of pleural membrane adherent to lung
pharynx
common passage for food, air, and liquids
larynx
vocal cords
trachea
flexible tube, held open with cartilage rings, branches into brochi
conduct, warm, humidify and filter air into lungs
function of airways
greatest, slowest
Air flow is ________ at the beginning of the airways, __________ at the end
ciliated
what type of epithelium is found in the trachea and bronchi?
saline and mucous layer
what covers the lumen of respiratory epithelium?
beat in waves to move mucous up and away from lungs
function of cillia
alveoli
air filled structures suited for gas exchange
elastin and collagen for elastic recoil
located between epithelial cells in the alveoli
Type I pneumocytes
thin epithelial cells lining most of the alveoli surface area
type II pneumocytes
-large cells that have smaller surface area, secrete surfactant
-move fluid out of air space
high, low
Pulmonary circulation is a _________ volume, _________ pressure system
25/8 mm/Hg
approximate pressure for pulmonary circulation
gas laws
state that gas, pressure, and volume are related to ventilatory properties
boyles’s law
shows pressure-volume relationships
-P1V1 = P2V2
increase
according to boyle’s law, if volume is decreased, the pressure will ___________
high, low
air moves from _________ pressure to _________ pressure
Dalton’s Law
total pressure exerted by a mixture of gases is sum of pressures exerted by individual gases
partial pressure
pressure of a single gas in a mixture
760 mmHg
what is atmospheric pressure?
multiply atm pressure by .21
if oxygen ins 21% of the Atm, how do you calculate partial pressure?
160 mmHg, 150 mmHg
what is the partial pressure of oxygen? with 100% humidity?
Partial pressures drive the diffusion of gasses across membranes
what is the significance of dalton’s law?
Respiratory cycle
airflow due to pressure gradients generated by actions of musculoskeletal pump
quiet breathing
used in resting conditions; expiration is passive
contraction expands thoracic cavity
function of diaphragm during quiet breathing
lift and expand the ribcage
function of scalene/external intercostals during quiet breathing
pleura
allow for lungs to move as the thoracic cage moves
forces on 2 membranes pulling in opposite directions
what generates negative intrapleural pressure?
fluid bond is broken causing the lung to collapse due to elastic recoil
what happens to the lung due to a pneumothorax
elastic recoil of lung and thoracic cavity
what does negative intrapleural pressure cause?
atm pressure is greater than alveolar pressure
why does air flow in to the lungs during inspiration?
brain
what controls activation of inspiratory muscles?
increased, decreases
during inspiration….____________ alveolar volume, ___________ alveolar pressure
atm pressure is less than alveolar pressure
why does air flow out of the lungs during expiration?
active expiration
requires additional actions of abdominal and internal intercostal muscles
decreased, increases
in expiration….. ____________ alveolar volume, ___________ alveolar pressure
compliance and elastance
what determines stretchability
compliance
measurement of forces needed to stretch lung, force generated by thoracic cavity movement
easy
high compliance = __________ to stretch
fibrosis
condition where lungs that are stiff, require high pressure to expand
emphysema
Condition where alveolar walls lost, lungs are loose and floppy with high compliance
inversely
how is elastane related to compliance?
elastance
result of elastic properties connective tissue inside the lungs
high
lungs with _________ elastance return to original shape easily
high
Elastance in lungs with fibrosis is……
low
Elastance in lungs with emphysema is……
inhalation, exhalation
compliance is associated with _________ while elastance is associated with _________
H-bonding between water molecules in the thin water based fluid lining alveoli
what caused surface tension to develop in the lungs?
air/water interface
where is surface tension found?
surfactant
reduces cohesive forces b/w water molecules, reducing ST and work
needed to expand alveoli
type II phneumocytes
secrete surfactant
surfactant not produced yet in premature infants
what causes newborn respiratory distress syndrome?
length of system, viscosity, radius of system
what factors affect airway resistance?
paracrine and nervous systems
what controls the radius of airways
trachea and bronchi
what accounts for most resistance int he airways?
parasympathetic signaling for bronchoconstriction
what does histamine cause?
sympathetic signals for bronchodialation
what do increased CO2 levels and epinephrine cause?
constriction of smooth muscle
what increases resistance of bronchioles?
total pulmonary ventilation
refers to volume of air moved by lungs per unit time (typically minutes)
tidal volume
volume of air in or out per breath
anatomical dead space
volume where air is not completely eliminated from body: not all of this is available for gas exchange, some is stuck in conducting pathway
150 mL per breath
approx volume of anatomical dead space
alveolar ventilation
volume of air available for gas exchange
= Tidal Volume – Anatomical Dead space
ventilation-perfusion matching
airflow matching blood flow to ensure adequate oxygenation of blood
constriction of bronchioles and mucus
what causes asthma
bronchiole dialators
how is asthma treated?
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