Respiration 1 - 4 Flashcards
2 types of respiration
internal external relies on diffusion and gradients effect of diffusion - linked to distance inc distance = inc time for diffusion
internal respiration
in cell
CO2 produced - glycolysis, Krebs cycle, O2 consumed - Ox Phos
external respiration
ventilation
exchange and transport of gases around body
lungs contain multiple branches
broken into 2 zones
1 - conducting zone
2 - respiratory zone
bronchioles more subjected to collapsing, rely on elastic tissue around them to keep open
conducting zone
not involved in gas exchange
transports gases to respiratory zone
nose, mouth, pharynx, trachea, bronchial tree
functions: conditions incoming air - filter, warm, humidify
solubility of gas decreases with heat inc
humidity stops lower airway drying out
structure of bronchial wall
reinforced with cartilage rings, prevents collapsing
layer of smooth muscle, contraction reduces airway diameter
mucous glands, respiratory epithelium, traps particles
elastic tissue, helps support airways
respiratory epithelium
lines lumen, ciliated epithelial cells, direct mucus out of lungs into throat
goblet cells - produce mucus
sensory nerve endings - help detect noxious chemical in airways
bronchioles
less than 1mm diameter
lack cartilage support, use elastic tissue to stay open
in COPD, elastic tissue is broken down = more likely to collapse
lined by repiratory epithelia
more smooth muscle
alveoli
large SA = huge area, small diffusion pathway
fed from terminal bronchiole
thin walled epithelial layer
air blood barrier
epithelium type 1 = makes up most of area, very thin cells
sandwich created by flattened cytoplasm of type 1 pnemocyte and capillary wall
for gas exchange to take place multiple barriers have to be crossed
large SA for exchange
ventilation
inspiration and expiration, quiet (rest), forced (active)
movement of air down pressure gradient
inspiration vs atmosphere
Patmos > Palv so air moves into lungs
expiration vs atmosphere
Palv > Patmos so air moves out of lungs
quiet inspiration
involves primary muscles of inspiration
diaphragm - contracts and moves down
external intercostals - lifts ribs
effect = inc thoracic space and lung volume
air movement follows Boyles law - inc vol leads to reduced pressure, air moves into lungs and down gradient
forced inspiration
involves secondary muscle (accessory)
scalenes - attach to ribs and pulls up and forward
sternocleidomastoids - attach to sternum - lift and pull forward
= expand thoracic cavity
neck and back muscles - pull pelvic girdle - expand rib cage
upper respiratory tract muscles - reduce resistance to airflow
quiet expiration
passive process using elastic recoil, no primary muscles
relaxation of external intercostal muscles
recoil of lungs (elastic forces returning lungs to original size)
forced expiration
accessory muscles, active process
contraction of abdominal muscles - push diaphragm up
neck and back muscles - push pelvic girdle - bring ribcage in
internal intercostals - bring ribcage back down
pleura
tough membrane lines chest wall and outside lungs
fluid filled space, allows lung and chest wall to move over each other
prevents lungs from sticking to chest wall
enables free expansion and collapse of lungs
elastic forces at rest
elastic forces in lungs and chest balance
elastic nature of lungs would tend to cause them to collapse inwards
chest wall would tend to expand
so inward = outward forces
pressure in interpleural space < Patmos
pneumothorax
collasped lung trauma creates breach in chest wall breaks pleural memebrane on chest inter pleural space is at atmos pressure - eqm = loss of force that keeps lungs inflated elastic nature takes over == collapse
compliance
measure of elasticity
compliance = distensibility
C = delta volume / delta pressure
shows the ease with which the lungs and thorax expand during pressure changes
low compliance
more work required to inspire
e.g. pulmonary fibrosis - lung parenchyma is more rigid - harder to expand
high compliance
difficulty expiring - loss of elastic recoil
e.g. emphysema and COPD - airways can collapse
effect of disease states on compliance
fibrosis - small delta volume
emphysema - larger delta volume
same change in pressure
components of elastic recoil
2 major components
1 - anatomical, elastic nature of cells and extra cellular matrix
2 - elastic recoil due to surface tension generated at air - fluid interface
effect of surface tension on compliance
inflating with liquid - saline
- linear increase in volume
inflating with air
- have to overcome surface tension, inc pressure to overcome then smaller airways open - linear filling
surface tension
due to difference in forces on water molecules at air/water interface
in a gas bubble there is balance between pressure exerted by gas and surface tension at gas/water interface = Laplace’s equation
P= 2xSt/radius
surface of bubble will become smaller due to water molecules pulling away
bubble shrinks = pressure inside increases, then reach point where 2 balance in lung
many air sacs of different volume
larger sacs = lower pressure than in smaller
air will flow from smaller alveoli to larger leading to their collapse
surfactant
overcomes problem of smaller alveoli collapsing
produced by type II pnemocytes - made of lipids and proteins (type I for gas exchange)
lipid molecules partition into air/water interface due to hydrophilic and phobic parts which relieves surface tension by decreasing density of water molecules, because hydrophobic tail pulls surfactant molecule upwards
resultant vector = minimal
small alveoli = more surfactant, balances surface tension and pressure between alevoli and stops smaller ones collapsing
when we breathe in, alveoli = full, surfactant decreases, surface tension increases to stop them overfilling
lung volumes
simple spirometer
measures all volumes apart from residual
dead space
volume not involved in gas exchange
- anatomical = volume of conducting airways, at rest approx 30% of inspired air volume
- physiological = includes anatomical dead space, conducting zone + non functional areas of respiratory zone
normally 2 values are almost identical
