RR- airway/histology/oxygen

what are the 5 roles of the airways and airspaces

• move O2 in

• move CO2 out

• warm and humidify air

• facilitate gas exchange

• defense against unwanted intrusion

A

trachea

B

main bronchus

C

lobar bronchus

D

segmental bronchus

E

terminal bronchus

F

respiratory bronchioles

G

alveolar duct

H

alveolar sacs

I

alveoli

if a pt were to aspirate something from the mouth into their lungs, what area would it likely lodge in the lungs, why

in the R lung in the middle or lower lobe- where the bronchus has the longest and straightest pathway to the lungs

describe the action of the larynx and epiglottis to protect the trachea when swallowing

larynx rises towards the epiglottis closing off the opening to the trachea

Does total resistance in the airways increase or decrease as the airways become smaller toward the end of the air pathway? Why is this? 

As you move distally in the airway tree, the diameter of any single airway becomes smaller so resistance of any given airway increases. However, there is such a large increase in the total number of airways that the overall cross-sectional area for airflow is very high in the distal airways and the overall airways resistance is quite low in this region.

what is the major mechanism to protect the respiratory tract from invaders

mucociliary escalator

how can mucociliary escalator be damaged in infection

during post-influenza infections, the epithelium can be denuded and have no ciliary to move the invaders out

what is the main difference between the conducting zone and the respiratory zone

there is no gas exchange in the conducting zone

what structures are included in the conducting zone

trachea → bronchi → terminal bronchioles

what structures are included in the respiratory zone

respiratory bronchioles → alveolar ducts → alveolar sacs → alveoli

__________ is the key structural element of the distal airways

smooth muscles

how does smooth muscle control flow

contraction and relaxation regulates the distribution of air flow to help match ventilation w perfusion

why is it really important that capillary/alveoli barrier is very thin

allows easy diffusion for O2 in one direct and CO2 in the other direction

capillaries form a continuous sheet of blood in the wall of the alveolus that greatly _________ (inc/dec) the surface area

inc

there is a significant risk in the capillaries/alveoli barrier being so thin, what is this

susceptible to leakage and injury w inc intraluminal pressure

what pneumocyte coats most of the alveolar surface

type 1

which pneumocyte makes surfactant, can repopulate after injury/resistant to injury

type 2

what is the function of the conducting zone

conduct, filter, warm and moisten inhaled air

what is the conducting composed of

nose, pharynx, larynx, trachea, bronchi, terminal bronchioles

the conducting zone is lined by…

respiratory mucosa composed of ciliated columnar epithelium and submucosal seromucous glands

the respiratory zone participates in…

gas exchange

what is the respiratory zone composed of

respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli

what is the respiratory zone lined by

alveolar epithelium composed of type 1 and 2 pneumocytes- thin squamous epithelium

how many cartilage rings are there in the trachea, what are they shaped as

16-20 “c”-shaped rings

what is the function of the cartilage rings in the trachea

mechanical stability

the main bronchi have ____________________ and smaller bronchi have ______________

cartilage rings; irregular plates of cartilage

what is the branching order starting from bronchi

bronchi → lobar bronchi → segmental bronchi → terminal bronchioles → respiratory bronchioles

what structures consists of the following characteristics:

intralobular air tubes, 1-5 mm diameter, formed after ~10 generations of branching

bronchioles

describe the epithelium of large bronchioles

ciliated pseudo-stratified columnar

describe the epithelium in smaller terminal bronchioles

simple columnar becoming cuboidal

there are few _________ cells in bronchioles and entirely gone by the smallest bronchioles

goblet

_________ and __________ are abundant in bronchioles

elastin and smooth muscle

what is present in bronchi but not in bronchioles

cartilage and submucosal glands are present in bronchi but not bronchioles

what do pulmonary arteries carry

deoxygenated blood from the RV to the alveolar bed

pulmonary arteries travel alongside…

bronchial/bronchiolar tree

what do pulmonary veins carry

oxygenated blood from alveolar bed to LA

pulmonary veins are not associated w…

bronchial/bronchiolar tree

do pulmonary arteries or pulmonary veins have a thick wall

pulmonary arteries; contains elastic lamina

what is the role of smooth muscle in the respiratory tract

contracts/relaxes to narrow/dilate air tubes; regulates

the respiratory tract is under ____________ innervation

autonomic

_________ NS will dilate while the ___________ NS will constrict

sympathetic; parasympathetic

where is mucociliary apparatus located

ciliated epithelium lines the trachea and the bronchi all the way down to the smaller bronchioles

what is the function of the mucociliary escalator

constantly beats to move mucus and debris upward along the bronchial tree and trachea- most of this content is unconsciously swallowed

what structure marks the end of the conducting part of the pulmonary tree

terminal bronchiole

type 1 pneumocytes are _________ cells and cover ________% of alveolar surface area

squamous; 95

type 1 pneumocytes are thin for _________ and are part of the __________ barrier

diffusion; blood-air

type 2 pneumocytes are _______ cells and cover ___% of the alveolar surface area

cuboidal; 5

function of surfactant

acts a detergent and reduces surface tension to prevent airspace collapse

what are the three ways we measure the “amount of oxygen” and what are the units

gas tensions in ambient air and oxygen tensions in inspired air and alveolar air; all measured in mmHg

F_iO₂ (inspired fraction of O₂) doesn’t change as long as the person is in the earth’s atmosphere, but the ambient PO₂ does change, depending on where the patient is.  Why?

scenario 1: in my house chilling, I am breathing normal 21% O₂, feeling good, PO₂ would be high

scenario 2: I am on everest- high elevation, there is not a lot of oxygen there, but there is still 21% technically, but still not enough, and my body is requiring more oxygen, this would mean my PO₂ would be low

what is F₁O₂

inspired fraction of O₂, always 21%;

what is P₁O₂

partial pressure of inspired O₂

what is P_AO₂

alveolar partial pressure of O₂

what is P_aO₂

arterial partial pressure of O₂

explain P_AO₂

it is the partial pressure of O₂ being delivered to the alveoli; influx of O₂ from the air

influx of O₂ into the alveoli is a funx of…

• the ventilation (V_A)

• the inspired partial pressure of O2 (P₁O₂)

what is S_aO₂

O₂ saturation % of arterial Hb; this does not give us information about how much Hb is available to carry the O₂

what is the alveolar gas equation

in words what is the alveolar gas equation

alveolar pressure of O₂ = oxygen coming into the alveolus - oxygen going out of the alveolus going into the blood

in the case of a pts hypoxic event, how can we figure out the appropriate tx using the alveolar gas equation

compare P_AO₂ to P_aO₂

what does (P_ATM - P_H2O) x FiO2 represent

how much O2 is brought into the alveolus (oxygen in); also can be represented as P_iO₂

what does (P_aCO₂)/R represent

how much oxygen is taken away from the alveolus (oxygen out) into the blood

what does R represent

respiratory exchange rate; the ratio of the amount of oxygen intake to the CO₂ out-take; is ~0.8

at sea level, barometric pressure (P_ATM) is…

760 (this will change w altitude change)

what is saturated vapor pressure (P_H2O) of water at body temperature

47

at sea level, P_iO₂ =

(P_ATM - P_H2O) x F_iO₂ →→→ (760 - 47) x .21 = ~150

how does F₁O₂ change if altitude inc

it doesn’t… unless you go to all the way to space

how does P₁O₂ change if altitude inc

decreases- inc altitude would inc barometric pressure (P_ATM)

how does P_AO₂ change if altitude inc

will dec due to the dec in P₁O₂

how does P_aO₂ change if altitude inc

will dec bc P_AO₂ is dec

oxygen consumption in the body can be estimated by…

PCO₂ / R

when going to an inc altitude, you resting heart rate can be elevated, explain this

this is your bodies response to acute decreases in P_aO₂ AKA acute hypoxia; your body is inc hr to inc CO to try to pump more O2 through the body by pumping blood faster through the body

can we measure PCO₂ or PO₂ more easily

PCO₂

____________ diffuses quickly from blood into the alveoli and vise-versa so we can assume _______=___________

CO₂; P_ACO₂ = P_aCO₂

does CO₂ or O₂ diffuse faster

CO2

does diffusion of the oxygen from alveoli to the red cells in the blood happen quickly or slowly if a person is at rest and at sea level

quickly

give a scenario where the diffusion of the oxygen from alveoli to the red cells in the blood happens slowly

in an exercising individual; when the barrier is thickened; higher elevation

function of hemoglobin

transports oxygen in the blood

what is the oxygen-hemoglobin dissociation curve

plots how saturated the hemoglobin is in the presence of a given partial pressure o oxygen

pulse-oximetry measures ___________ of oxygen in the Hb but does NOT tell you about the _________ of oxygen

saturation; content (only tells you how well the Hb is carrying the O2 not how much Hb is there)

a person w anemia may show to have a normal oxygen saturation by pulse oximetry but have low Hb, what is rlly happening

it shows they have normal oxygen saturation bc the Hb that are present are saturated w O2, but this doesn’t tell us how many Hb are present

what is P₅₀

describes the hemoglobin affinity for oxygen when 50% of hemoglobin binding sites are being used

describe a right shift happening in the dissociation curve

right shift means there is an inc in P₅₀ → decreased affinity for Hb holding onto O₂ compared to normal

factors that can cause a right shift in the dissociation curve

• dec pH

• inc PCO₂

• higher temp

• inc 2,3 DPG-diphosphoglycerate

describe a left shift happening in the dissociation curve

left shift means there is a dec in P₅₀ → inc affinity for Hb holding onto O₂ compared to normal

factors that can cause a left shift in the dissociation curve

• inc pH

• dec PCO₂

• lower temp

think about the oxygen-Hb dissociation curve, in the lungs would be want a left or right shift

left shift- to get rid of CO₂ and grab O₂

think about the oxygen-Hb dissociation curve, in the tissues would be want a left or right shift

right shift- to get rid of O₂ and grab CO₂

is there more oxygen carried in hemoglobin or dissolved in the blood in the normal human

more dissolved in blood