Respiration Flashcards
Gas Exchange in Lungs: 2 places

- O2 delivery and CO2 removal
- (1) gas exchange at lungs & (2) tissues
- gas exchange in lung to take O2 to tissue where metabolism happens like skeletal muscle
- oxygen first goes to heart and then to body where exchange gases and then non oxygenated blood goes back to heart and lungs
- pulmonary artery carries deoxygenated blood
- pulmonary vein carries oxygenated blood
- in body system is where O2 diffuses out of blood into tissues and that gradient also has to support O2 diffusion

Diffusion is key & Fick Equation
- how gases move, no pumping
- look at partial pressure of gas
- rate of diffusion = diffusion coefficient permeability x area x partial pressure gradient/distance
- depends on permeability

To maximize delivery
- increase surface area
- thin membrane for a small distance - thin respiratory membranes
- maximize partial pressure gradient by matching airflow to blood flow
- gases diffuse according to partial pressure gradient
- set up gradient w/in lung to max mvmt of O2 out of lung and into blood
- go from high PP to low PP and difference facilitates that
- humans use 250 mL O2 /min
Thoracic Cavity and Muscles
- respiratory system in thoracic cavity bounded by diaphragm which is a major muscle for respiration
- upper respiratory system - top of trachea and then mouth and nasal cavity where take air in
- lower respiratory system - trachae and lung w/diaphram and external intercostals, scalinas, sternoclyomastids for breathing in
- diaphram, adb and internal intercostals for breath out
- move air in and out of lungs via diaphragm

Muscles of inspiration and expiration
- muscles of inspiration - inhale use diaphragm and external intercostales, which is btwn ribs and lift ribs up and out
- sternocleido/sternoclyomastids and stelanous/scalinas for deeper breaths to lift up rib
- muscles of expiration - when exhale your diaphragm relaxes, and muscles help w/more forceful exhalation we have internal intercostals to move ribs down and in and helps to breath out
- also abdominal muscles which push in and up on diaphragm to put pressure on thorasic cavity ; breath out

Cavities and Membranes
- base of lung is bottom, top is apex
- in L lung there is space carved out like a heart called cardiac notch
- dorsal back and ventral front side and heart sits between
- pleural membranes -
- visceral membrane is on the lung
- parietal membrane is on inside of thorasic cavity
- the membranes are right next to each other and the space between is the intra plural space and is below barometric pressure (pB); NEGATIVE PRESSURE; KEEPS LUNGS INFLATED
- really hard to get two wet plates apart like these membrane

Respiratory Tree
- conducting zone - larnynx, trachae and then bronchi are divided and have smooth muscle around them so can affect AIR FLOW until you get area of gas exchange in alveoli
- action for gas exchange in alveoli - bronchi branch into smaller vessels called bronchioles which have smoooth muscle around them which can adjust and contract to adjust radius of bronchi to some degree

Flow Equation
Flow = driving pressure x r4
- driving pressure times radius
Asthmatics
- smooth muscle contracts and constricts/reduces airways
- flow through bronchi and down into alveoli is proportional to driving pressure we use to move air times the radius to the fourth power which is why things get very dramatic when adjust radius
- small change in radius of bronchi make huge change in air flow which is why keep opena dn reasonably sized is important
Alveoli and Capillary Network
- alveoli are thin structures and capillary network surrounds each alveoli so capillaries pick up O2 and assoc w/blood flow and each alveoli
- alveoli 200-350 microns in diameter - small w/HUGE SA so they inflate and deflate
- elastic fibers around each alveoli - when inflate we push out elastic fibers; “rebound”, so very little energy required to breath (1-2% of energy budget) mostly inspiration
- when exhale elastic fibers push back and help us push air out
- most of our energy on breathing is inhalation, exhalastion is about free energy at rest

Trachea
- trachea keep airways clean - goblet cells w/mucous pushed to the surface so cells taht are ciliated beat and try to trap particulate matter in mucous and use cilia to push back into mucous and keep respiratory tract clean/clear
- smooking paralyzes the cilia so hard to keep trachea clean of particulate matter

Alveoli Details
- Type 1 cells make up structure of alveoli and involved in gas exchange
- Type 2 cells - make pulmonary surfactant which decreases surface tension and helps enlarge alveoli
- capillaries - want intimate association between circulation and blood flow so only 1 row of endothelial cells around
- surfactant is put in water layer which improves stability and easier to inflate (less surface tension and pressure)
- child born too early has respiratory distress syndrome is born too eary and not enought surfactant so hard to breathe - induce surfactant w/cortisol higher

Exchange surface of alveoli
- rbc in capillary
- lining of pulmonary surfactant of pumonary space and O2 then has to go through alveolar cell w/2 cell membranes one on either side and then goes through capillary endothelial wall which is 2 membranes
- then goes into plasma which is liquid of blood and most of O2 is carried via RBC and goes through that cell membrane too
- total of 5 membranes for O2 to cross before gets carried away
- O2 is very permeable to cell membranes and respiratory membranes are thin

Cross sectional area is important
- as go deeper into respiratory system the diameter of these get smaller and they also increase in number exponentially
- their cross sectional area > too!

Conducting & respiratory zone

- number 17 is respiratory zone
- at 17 of airway generation, we get into respiratory zone and the total cross sectional area just sky rockets
- this is how we support our MR w/high need for O2, since all this area to exchange gases

Thoracic Cavity and Muscles
- diaphragm is big main muscle to separate abd from thoracic cavity
- intrapleural pressure always bit neg since not let alveoli collapse

Breathing: Mechanics
- at rest, diaphragm is relaxed
- diaphragm moves down and contracts and thoracic volume increases - inhale
- decrease pressure in thoracic cavity which is intrapleural pressure
- suck in air since lower pressure of alveoli and so alv pressure is less than atm pressure
- diaphragm relaxes and rises and thoracis vol decreases - exhale
- > intrapleural pressure but still neg
- > alveolar pressure so greater than baro pressure and air leaves lungs
- 3 pressures to be concerned about - intrapleural pressure is always neg., intraalveolar pressure, and barometric pressure (pB)
- inhalation - diaphragm contracts and moves downa nd we decrease intrapleural pressure to make it more negative, whcih drops intraalveolar pressure which goes neg., so pB greater than Alvp and air flows from high to low, so air flow from pB to outside into the lung like suction
- exhalation - diaphragm relaxes and fills w/air - will increase intrapleural pressure (still neg but less); pressure in thoracic caviety so pressure on alveoli so > intraalveolar pressure, now AlvP > pB so air flows out and thats our exhalation
- pressure pump

Diaphragm like pump handle
- contracting diaphram until < pressure in lung so Pb > Palv so inhale
- relax diaphram will increase pressure in lungs so Pb < Pa and exhale
- when move pump handle up and rib up then increase anterior-posterior dimensions of rib cage
- bucket handle increases lateral dimension of rib cage

Passive expiration and active expiration w/muscles and pic of general inhalation and exhalation

at rest before inspiration, move ribs down and drop in intrapleural pressure and can use extra muscles too if need it
- Diaphragm relaxes and comes back up and sets up chamber, more forceful expiration you use abdominal muscles and abdominal muscles
- Pressure changes are responsible for response of alveolar to these pressure changes
Active expiration, during which contraction of the abdominal muscles increases the intra-abdominal pressure, exerting an upward force on the diaphragm. This reduces the vertical dimension of the thoracic cavity further than it is reduced during quiet passive expiration. Contraction of the internal intercostal muscles decreases the front-to-back and side-to-side dimensions by flattening the ribs and sternum.
Pressure and Volume Changes while Breathing
normal breath about 500 ml
inhale intrapleural pressure begin at -3 and on inhale get to -6
at inhale alveolar pressure begins low and then increases to bring air in
when Pb = Pa then no net air flow
- move 500 mL air in and 500 mL out
- intrapleural pressure - starts negative and when we in bring it more negative
- as exhale it goes back up but still neg
- alveolar pressure - at beginning of inhalation its no diff from atm pressure(pB) but at end of we bring back to pB but differs in middle
- exhale the intrapleural pressure is less neg since compress thoracic cavity and extra air in lung
- alveolar pressure goes up and start forcing air out since alvP > pB
- by end of exhalation forced air out and back to pB in alveolar pressure so equal
- exhale the intrapleural pressure is less neg since compress thoracic cavity and extra air in lung
- deeper breath - bottom graph peak is higher, greater volume
- intrapleural pressure graph goes even more neg and at end of breath goes back to normal so deeper trough not peak
- alveolar graph - alveolar pressure drops more than normal but by end of inhalation still at zero and exhalation is higher peak too

Intrapleural pressure is always negative
- neg intrapleural presssure - elastic recoil of chest wall tries to pull chest wall outward and that of lung creates inward pull
- if puncture lung - you create a hole and pressure in chest cavity equilibriates to pB and lose neg pressure and lung collapses
- to keep lung inflated you need that neg pressure
- can put cord and generate suction and neg pressure and reflate teh lung
- lungs naturally collapse unless sitting in neg pressure - geared to collapse since elastic around them

Law of LaPlace

- in alveoli: thin layer of fluid inside and air inside = surface tension of alveoli (water-air interface) –> this generates pressure that wants to pull alveoli in to cuase it to collapse
- Law of La Place is pressure of alveolus = 2T/r
- smaller the r, the more pressure, the more likely to collapse - less stable
- small alveolus will have more pressure than larger one, so the small blows up the bigger one

Pulmonary Surfactant
- helps surface tension is a 16 carbon fatty acid + phosphotydylcholine
- overall effect is to decrease surface tension so less likely to collapse
- increase stability of alveoli
- helps keep alveoli dry
- increase compliance of lung so easier to inflate w/pressures we have

Compliance Curve - how easily the lung can inflate
“hysteresis” - diff in these curves
- hystersis - 2 sep curves due to air-water interface
- change in pressure is alveolar pressure - intrapleural pressure












