respiration - lecture 1 Flashcards
what is primary function of respiration
gas exchange
what is inspiration
air rich in oxygen inhaled into lungs
what is expiration
carbon dioxide produced during oxidative processes of body is exhaled from lungs
which system is closely related to respiratory system
both gases are transported by the blood
both cardiovascular system and respiratory system involved
describe respiratory tract
first through nasal turbinates = nose/mouth, filters, catches, dust and particles
common passage of pharynx = air and food which then split = larynx - vocal chords, sound and speech
trachea = cartilage splits into right and left main bronchi then split smaller and smaller to alveolar region = gas exchange
alveoli = small balloons, covered by capillaries = blood comes from heart and becomes oxygenated and goes back = got rid of co2
airway tree = lots of space for gas exchange
how do lungs inflate
lungs do not inflate on own - muscles of ribcage and coupling of ribcage and lungs
done by pleural space - v thin
intercostal muscles - allow for inflation
what is pleural space
small amount of fluid
parietal pleura = attached to inside ribcage
visceral pleura = attached to alveoli
pleural space = one per lung, not continuous, creates coupling of ribcage and lungs
how to visualize pleural surfaces
drop of water between 2 glass microscope slides = the 2 slides can easily slide over each other but cannot be pulled apart - creates suction = how we breathe
describe when ribcage enlarges
enlarges size of lungs = coupling
bigger vol = less pressure so air flows inside lungs down pressure gradient
describe normal pleural space
p=0 outside
p=0 inside lung
no air in or out since equal pressures
in pleural space p=-5, negative pressure, lungs like balloon, always want to collapse, lungs pull more than ribcage (which wants to spring out, opposing forces so neg)
describe pneumothorax pleural space
p=0 in pleural space
accident = hole through ribcage removes coupling so lungs deflate and ribcage expands = pneumothorax, usually only on one lung since pleural spaces discontinuous
removes coupling
describe mechanical pump
syringe = pull down plunger = neg pressure = air moves in and expands like balloon
when respiratory muscles contract = diaphragm and intercostals contract = increase size of ribcage so decrease pressure = holds lung open and causes air to move in
describe bronchi splitting
right main bronchus - split into 3 lobar bronchi
left = split into 2 lobar bronchi
name and describe subdivisions of respiratory system
conducting zone = trachea, bronchi, bronchioles, terminal bronchioles
respiratory zone = respiratory bronchioles (alveoli budding in walls), alveolar ducts (filled with alveoli), alveolar sacs
describe acinus
bronchi = have rings then plaques of cartilage
bronchioles = no cartilage
smooth muscle = involuntary, cannot control, holds tone of airways
asthma = contract and constrict airways and decrease air flow
name the 4 main functions of conducting airways
defence against bacterial infection and foreign particles
warm and moisten inhaled air
sound and speech
regulation of airflow
describe defence against bacterial infection and foreign particles - main functions of conducting airways
epithelial lining of bronchi = has cilia - beat upwards
epithelial glands secrete a thick substance = mucous which lines respiratory passages as far down as bronchioles
foreign particles stick to mucous and cilia sweep mucous up into pharynx = mucociliary defence system
helps swallow or spit out
describe sound and speech - main functions of conducting airways
produced by movement of air passing over vocal chords - larynx
describe regulation of airflow - main functions of conducting airways
smooth muscle around the airways may contract or relax to alter resistance to air flow - in whole respiratory tract
what is function of respiratory zone
site of gas exchange between the air in the alveoli and the blood in the pulmonary capillaries
~300 million alveoli in the human lungs - each alveolus
may be associated with as many as 1000 capillaries
describe heart and lungs together
inferior vena cava = mixed venous blood - right side and goes to lungs through left and right pulmonary arteries and then comes back into left heart through left and right pulmonary veins and goes to whole body through aorta and also to airway to get oxygenated
how many circulations do lungs have
2 = pulmonary and bronchial
describe pulmonary circulation
bring mixed venous blood to lungs
allows for blood to get oxygenated and then to be taken back to heart
describe bronchial circulation
supplying oxygenated blood from systemic circulation to tracheobronchial tree = circulation allows airways to get oxygenated
describe bronchial artery
from left heart via aorta
is not much blood going to airways - some goes back to venous system - anastomosis with oxygenated blood - mixed venous blood, and goes back to heart
name the 3 alveolar cell types
epithelial type 1 and 2 cells
endothelial cells
alveolar macrophages
describe epithelial type 1 and 2 cells
line alveoli
little known about specific metabolic activities of type 1 cells
type 2 cells produce pulmonary surfactant = substance that decreases surface tension of alveoli
describe endothelial cells
constitute the walls of pulmonary capillaries
may be as thin as 0.1microns
describe alveolar macrophages
remove foreign particles that have escaped mucociliary defence system of airways and found way into alveoli
describe alveolar capillary membrane
interstitium = space between alveoli and blood vessels
describe surface tension - specific
The surface tension of the liquid film lining the lungs is an important contributor to the mechanical properties of the respiratory system
tension arises because the molecules in the surface of the film tend to arrange themselves in the configuration involving the lowest energy
Being more attracted to themselves than to air, they like to “hold hands” rather than freely associate with air molecules
This causes a tension to be generated across the film surface
describe surface tension - gen
everything is lined with a bit of water = air water interface with tension, like soap bubble
surface tension at air liquid interface since forces between water molecules greater than forces between water molecules and air
describe what happens with surface tension when surface curved
like on inside alveoli
tension can produce a pressure that tends to collapse alveolus
vectors add up to pressure that tends to collapse soap bubbles
need surfactant - tends to collapse all the alveoli
describe alveoli modelling - soap bubble
pressure - p - inside soap bubble radius - r - results from surface tensionT = laplace’s law
p=4T/r
the smaller the bubble = smaller r = greater pressure
small would empty into large = bad system
describe pulmonary surfactant
decreases tension and smaller alveoli more
small alveoli will collapse, emptying into large ones = prevented from happening by secretion of pulmonary surfactant by alveolar type II cells
name the first primary role of pulmonary surfactant
making surface tension inside alveoli change with lung vol = prevents pressure inside small alveoli from exceeding pressure of large = biophysical properties that decrease surface tension to a greater extend in smaller than larger alveoli
surfactant = stacks up in many layers, helps better than being spread thin
name the second primary role of pulmonary surfactant
reducing overal surface tension so we can breathe
if surface tension in liquid layer lining was equal to water = would not be able to inflate lungs
describe respiratory muscles
lung tissue = elastic but cannot expand or contract by itself
air must be sucked into lungs
function powered by respiratory system muscles of chest wall
name the 2 types of respiratory muscles
inspiratory and expiratory
describe principal muscles of inspiration
external intercostals = elevate ribs
parasternal intercartilaginous muscles = elevate ribs, when contract = increase cross sectional dimension of ribs
diaphragm = dome descends, increases longitudinal dimension of chest and elevates lower ribs, separates ribcage from abdomen, bucket handle effect, dome down = increase longitudinal but also attached to lower ribs = bucket handle effect - moves lower ribs outwards = increase cross sectional area too
describe accesory muscles of inspiration
do not use them = recruit during exercise or disease
sternocleido-mastoid = elevates sternum when contract
scalenus anteior middle and posterior = elevate and fix upper ribs
all increase cross sectional area
describe the quiet breathing muscles of expiration
expiration results from passive recoil of lungs
ribcage goes back to original size
describe the active breathing muscles of expiration
recruits these =
internal intercostals, except parasternal intercartilaginous muscles = depress ribs and decreases cross sectional area
abdominal muscles = depress lower ribs, compress abdominal contents, recruit and pushes abdomen in and push diaphragm upwards and get back to original position
all lead to expiration = rectus abdominus, external oblique, internal oblqiue, transversus abdominus
what is diaphragm innverated by
phrenic nerves from cervical segments 3, 4 and 5
why do smokers cough up mucous
cilia get momentarily paralyzed by nicotine
when is surfactant produced
late in gestation and if premature = give drugs to mom so can develop lungs of baby, also artificial surfactant available
