Lecture 18: Pulmonary A&P Flashcards
what forms the thoracic cavity and what is contained within
formed by ribs, thoracic vertebrae, sternum, and clavicles
contains R and L pulmonary cavities and mediastinum
provides skeletal framework for attachment of mm used for breathing
describe the sternum and its components
flat breastbone; sits directly over mediastinum
manubrium = thickest part; articulates with clavicles and ribs 1-2
body = articulates with ribs 3-7
diploid = most caudal potion of sternum; doesn’t ossify until teens
angle of Louis = marks level of tracheal bifurcation into R and L main stem bronchi
what are vertebrosternal ribs
“true ribs”
ribs 1-7 attach to the sternum via the costal cartilage
what are vertebrochondral ribs
“false ribs”
ribs 8-10 attach to rib above via their costal cartilage
ribs 11-12 end freely
what is the weakest point of the rib
the shaft where vertebral and sternal end connects
purpose of inspiratory mm
increase volume of the thoracic cavity by producing “bucket handle” and “pump handle” movements of the ribs and sternum
diaphragm is the primary inspiration mm (phrenic nn C3-5)
external intercostals also assist with inspiration
how does the diaphragm move with breathing
moves downward with contraction to increase thoracic volume
vacuum effect pulls air into lungs
what do the intercostals do with inspiration
elevate ribs and expand chest
name the accessory inspiratory muscles
SCM
scalenes
upper trap
pec major and minor
serrates anterior
rhomboids
latissimus dorsi
serrates posterior superior
thoracic erector spinae
what muscles are involved with expiration
expiration = more passive than inspiration via elastic recoil; less energy required
abdominal mm = increase intra abdominal pressure for expulsion of air
internal intercostals = depress ribs and decrease thoracic volume
describe different anatomical components of the lungs
consists of airways and blood vessels to perform gas exchange
apex = superior cone shaped potion underneath and superior to rib 1
base = inferior/diaphragmatic surface
root = endurance of bronchi, pulmonary arteries/veins, lymphatics, nn into each lung
hilum = mediastinal surface where structures of the root enter the lung
describe the R lung
larger
3 lobes (superior, middle, inferior)
2 fissures ( horizontal and oblique)
describe the L lung
smaller
2 lobes (superior and inferior)
1 fissure (oblique)
cardiac notch
what is the purpose of dividing lungs into segments
R and L lungs are broken down into segments that correspond with their air supply
used for naming location of infection, surgery, tumor, fluid accumulation, etc
describe the parietal pleura
on chest wall
highly innervated
capillaries receive blood from systemic circulation
higher capillary blood pressure
describe the visceral pleura
directly on lungs
no sensory innervation
capillaries receive blood from pulmonary circulation
lower capillary blood pressure
describe the difference in blood vessels that vascularize the parietal pleura vs the visceral pleura
parietal = vascularized by high pressure systemic blood vessels
visceral = vascularized by low pressure pulmonary blood vessels
how does the pressure gradient work to move fluid in and out of the pleural region
normal pressure gradient causes constant fluid movement out of the parietal capillaries into the pleural space and is then reabsorbed by visceral capillaries
how much fluid passes through the pleural space
5-10L fluid per day
what are the components of the upper respiratory tract and their function
nose = air filtration, humidification, temp control, and olfaction
pharynx = throat; connects nasal cavity to tracheoesophageal junction
larynx = voice box; sits directly on top of the trachea
what are the components of the lower respiratory tract and their function
trachea = large airway made of cartilage rings, elastic, and fibrous tissue; carina splits trachea into R and L mainstream bronchi
bronchi = airways that enter each lung
- R bronchi has steeper Ange
- bronchi become smaller as they turn into segmental and sub segmental bronchi
terminal units = brochioles, alveolar ducts, and alveoli
what is the conducting zone
no gas exchange
air movement only
what happens at the respiratory zone
gas exchange
what are type 1 pneumocytes (AT1)
flat cells that perform gas exchange
what are type 2 pneumocytes (AT2)
cuboid cells that produce surfactant
describe the anatomy of the epithelial lining
cilia = tiny hair like structures lining the respiratory epithelial surfaces
natural movements of cilia help trap and propel substances and secretions upwards in the respiratory tract
expectorate = cough
what is compliance property of lungs
distensibility of lung tissue
how well it can stretch with inhalation
what is elasticity property of lungs
ability to return to its initial size after being distended
hig levels of elastin and collagen allow for recoil
what is surface tension
maintained with surfactant to prevent airway collapse
ultimately allows lungs to get smaller during exhalation
what is airway diameter and resistance
controlled by autonomic nervous system
upper airways are responsible for higher airway resistance
lower airways are too irregular to influence airway resistance
what is ventilation
moving air in and out of lungs
relationship between mm. contractions and pressure fluctuations
- diaphragm and other mm of respiration contract
- decreased intrapulmonary pressure
- air moves into lungs
medulla role in regulation of breathing
inspiration and forced exhalation
pons role in regulation of breathing
pneumotaxic center
- rhythms of ventilation, timing of inhalation and exhalation, inhibits apneic breathing
apneustic center
- facilitates apneic or prolonged breathing patterns
function of motor cortex of frontal lobe in regulation of breathing
voluntary and conscious breathing
types of chemoreceptors and their function in regulation of breathing
central chemoreceptors
- located in medulla
- facilitates increasing respiratory depth and rate to restore normal blood gas levels
peripheral chemoreceptors
- located in carotid artery and aortic arch
- facilitates increased ventilation in response to high CO2 or low O2
function of irritant receptors in regulation of breathing
initiates cough reflex
function of stretch receptors in regulation of breathing
protects lung from excessive inflation
how does intrapulmonary and atmospheric pressure play a role in inhalation and exhalation
inhalation = decrease in intrapulmonary pressure allows air to flow in
exhalation = increase in intrapulmonary pressure allows air to be expelled out
what is intrapleural pressure
elastic tension of ling trying to collapse lungs
outward pull of thoracic wall trying to expand lungs
opposition creates negative pressure within pleural space
what are transmural pressures
Difference in pressure inside va outside lungs
intrapleural pressure is less than intrapulmonary
allows changes in lung volumes
describe the mechanics of breathing
intrapulmonary pressure inside lung decreases as lung volume increases during inspiration; pressure increases during expiration
intrapleural pressure in the pleural cavity becomes more negative as chest wall expands during inspiration; returns to initial value as chest wall recoils
volume of breath = during each breath the pressure gradients move 0.5 L of air into and out of the lungs
what is respiration/oxygenation
process of gas exchange in the lungs facilitated by diffusion
- delivers O2 used for energy production
- removal of CO2 waste product
occurs at alveolar-capillary membrane
- gas exchange occurs due to differences in pressure gradients between different gas molecules
what are partial pressures of gases and what are the values for atmospheric air
amount of pressure exerted by a gas within a mixture
nitrogen = 79.04%
oxygen = 20.93%
carbon dioxide = 0.03%
in liquid (i.e. blood) gases are dissolved in proportion to their partial pressures
what is diffusion in regard to respiration
partial pressures of O2 and CO2 exist in both alveoli (air) and capillary (blood)
gases will diffuse from high to low concentration across alveolar membrane
what is perfusion
amount of blood flow to the lungs
effects capacity for gas exchange
positional or regional
lungs have low resistance and low pressure vasculature
what is ventilation perfusion (V/Q) matching
distribution of gas (V) and blood (Q) at the alveolar level of capillary interface must be matched
both ventilation and perfusion are greater in gravity dependent areas
if perfusion > ventilation = shunt
- blood but no air
if ventilation > perfusion = dead space
- air but no blood
describe the cellular transport of O2 and CO2
O2 transported by binding with Hgb; delivery to tissue is dependent on blood flow and amount of O2 content
CO2 is transported by Hgb, bicarb, or plasma
acid base balance is maintained by lungs, kidneys, and liver
SpO2 of 90% corresponds to what partial pressure of O2
60 mmHg
minimum O2 concentration to prevent ischemia
L shift on oxyhemoglobin dissociation curve
Hgb hods onto O2 since tissues don’t need it
more O2 bound to Hgb
lower partial pressure O2
lower temp and mm work
higher blood pH
R shift on oxyhemoglobin dissociation curve
releases O2 to tissues that need it more
less O2 bound to Hgb
naturally happens during exercise
higher temp and mm work
lower blood pH (more acidic)
