Week 3- CR Anatomy/Physiology + Mechanics of Breathing Flashcards
Main functions of the respiratory system
Ventilation + gas exchange
Ventilation
- Movement of gas in/out lungs
- Stops from inhaling foreign particles via mucociliary clearance (MCC) + cough
Gas exchange: functions + to achieve the two functions what does there need to be
Diffusion of O2 into the blood + removal of CO2
–> Need air moved via thoracic cage + blood moved via the heart, both to the lungs
The functions of the respiratory system in CR physio are defined as:
gas movement + secretion
Upper Respiratory Anatomy + Function + what do nose hairs do
Nose / Nasal Cavity / Pharynx (throat) / Larynx
Nose hairs filtrate + trap larger particles (i.e. pollen)
What does the nose do
Passageway for air / - Warms, humidifies. + filters air
Nasal cavity
- Nasal cavity increases mucosal surface area + turbulence (slows airflow to allow time for air to be filtered/warmed)
Respiratory mucosa
Lines the nasal cavity and has ciliated epithelium that contain goblet cells which secrete mucus + trap inhaled particles
Pharynx
(Throat) Common passageway for air, food, + liquid
Larynx
Voice box
Lower Respiratory Tract (Function)
Conducting / gas exchange
Conducting part of LRT (Anatomy)
Trachea / L+R main bronchi / Lobar bronchi / Segmental bronchi / Bronchioles / Terminal bronchioles
2 Functions of the conducting part of LRT
(1) Conducts air into gaseous exchange part of lungs
(2) Traps smaller particles (i.e. bacteria) moved via the mucociliary escalator to pharynx where they are swallowed
CENTRAL airway lining of conducting part of LRT
> 2 mm diameter (i.e. main bronchi)
- Mucus layer, ciliated epithelium, goblet cells, submucosal glands.
- Think about function: has to have mucus which is prod. by goblet cells, + ciliated epithelium which are the hairs that assist.
PERIPHERAL airway lining of conducting part of LRT
<2mm diameter (i.e. terminal bronchiole)
- No mucus later, less/smaller cilia, clara cells (don’t make mucus)
Gaseous exchange part of LRT (anatomy)
Respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli
Function of the gaseous exchange part of LRT
Gas exchange between O2 + Co2 occurs via diffusion in alveoli that are ventilated + perfused
Alveolar ventilation (v)
4 L/min- amount of gas getting into alveoli
Diffusion
Movement of gases (high to low) betw. alveoli, plasma, + red blood cells.
Perfusion (Q)
Pulmonary blood flow - cardiac out ~ 5 L/min
Lung anatomy
3 R lobes (UL,ML,LL) (horiz./oblique fissure) - 10 segments
2 L lobes (UL, LL) (oblique fissure) - 8 segments
Purpose of pleural cavity
Provides lubrication to reduce friction when the lungs inflate + recoil during breathing.
- Contains a small amount of pleural fluid, which allows the 2 layers to glide over each other during inspir./expir.
Resting volume of lung determined by:
The outward spring of the rib cage + inward elastic recoil of the lung matrix
Visceral pleura (inner layer)
Attaches to the outer surface of lungs + lines the fissures
Parietal pleura (outer layer)
Attaches to the chest/thoracic wall + superior surface of the diaphragm
- Highly sensitive to pain due to innervation from the phrenic/intercostal nerves.
Steps of pleural surfaces working
- Lungs are elastic + want to recoil inwards
- The chest wall wants to expand outwards.
- B/c the 2 pleural surfaces are pulling in opp. directions, it creates a - pressure in the pleural cavity. (This is what keeps lungs expanded)
Pneumothorax
Air in the pleural cavity; - intrapleural pressure (Ppl is disrupted)
- Lungs collapse inward
(i. e. stab wound/punctured lung from rib)
True ribs
T1-T7; Attach directly to sternum/spine
False/floating ribs
False - 8-12 (5)
Floating - 11,12
Thoracic cage moves in these 2 directions:
AP (pump handle) - ribs 2-5 raised during inspiration
Lateral (bucket-handle) - ribs 9-10 move in an upwards + outwards direction during inspiration.
Anterior/posterior apex of the lung
Ant. - Sits 2.5 cm above the medial 1/3 clavicle
Post. - C7
Anterior/posterior base of the lung
Ant. - to rib 6
Lat - to rib 8
Post. - to 10th rib
Inferior border of R lung
6th rib in mid-clavicular line –> 8th rib in the mid-axillary line, + 10th rib posteriorly.
Medial border of R lung
Ant. - 6th rib from sternoclavicular joint
Post. - T1-T10 to side of spinous processes
Location of cardiac notch
Medial border of L lung, 3-4 cm deviation from 4-6 rib
U / M / L Zones
U - above 2nd ant. rib
M - betw 2nd/4th ribs
L - below 4th rib
Primary muscles of inspiration
(1) Diaphragm
external intercostals, parasternal intercostals + scalene
Accessory Inspiration Muscles
Sternocleidomastoid, UT, Pec major/minor, Serratus anterior, Thoracic extensors
Accessory Expiration Muscles
Abdominals / Internal Intercostals
Diaphragm
Inspiration: contracts or during exercise contracts on expiration too
Origin: Lower costal ribs, lumbar vertebra
Insertion: Central tendon
Innervates: C3,4,5
Tidal volume (Vt)
Volume of gas inspired/expired w/ each breath
Vital capacity (VC)
Volume of gas expired after a max inspiration to a max expiration (4L)
Total Lung Capacity (TLC)
Volume of gas in lungs after max inspiration (5L)
Functional Residual Capacity (FRC)
- A reserve for gas exchange/minimises work of breathing
- Volume of gas in the lungs @ the end of a normal (passive) expiration (2.5L)
What happens when FRC falls below closing volume?
Leads to atelectasis which is associated w/ reduced oxygenation, poor CO2 clearance, + an increased work of breathing.
Residual volume
Volume of gas remaining in the lungs after a max expiration (cannot be exhaled)
What happens to an increase in RV?
Occurs in obstructive lung disease due to air trapping.
- leads to altered resp. mechanics, increased work of breathing, + poor gas exchange.
Total Lung Capacity
Volume of gas in the lungs after a max inspiration
Atmospheric/barometric pressure
Pressure exerted by the gases in the air. (Sum of all the partial pressures of gases in the air)
Intra-alveoral pressure (Pa)
Pressure w/in the alveoli; falls w/ inspiration + rises w/ expiration
- always eventually equalises w/ atmospheric pressure.
Intrapleural pressure (Ppl) + how is this pressure created
Pressure w/in the pleural cavity + decreases on inspiration & increases on expiration.
- pressure created by chest wall wanting to expand out, while the lungs want to recoil in.
Mechanics of breathing @ rest - FRC
(Pb) - Barometric pressure @ mouth = 0
(Pa) - Pressure in lungs (alveolar pressure) = 0
Intrapleural pressure = -
(No airflow ; Pb=Pa)
Mechanics of breathing during inspiration
Intrapleural pressure becomes even more -, lungs want to recoil in even more when lungs get bigger
(1) Inspiratory muscles contract
(2) Thoracic cage expands
(3) Lungs expand (increase lung volume)
(4) Intrapleural + intraalveolar pressures decrease
(Pa[-2] < Pb [0] = airflow>lungs)
Mechanics of breathing end inspiration
Pressures are = again, airflow ceases
Pa=Pb
Mechanics of breathing during expiration
(1) Respiratory muscles relax
(2) Lungs passively recoil (to FRC)
(3) Alveolar pressure rises (becomes +) compared to mouth (barometric) pressure
so gas moves towards the mouth
Pa>Pb
Horizontal fissure on R
Just above the level of the 4th rib/nipple, ends @ oblique fissure
Oblique fissure of R/L
T3/T4 travels to base of lung
- Follows lines of medial scap w/ arm abducted @ 90
Total (or minute) ventilation (Ve)
Vt (tidal volume[500ml]) x RR (resp. rate) = 6 L/min
- Mass movement of gas in/out of lung
Alveolar ventilation (Va) + equation
- The amount of fresh gas getting to the alveoli.
Va= (Vt-Vd) x RR ~ 4.2L/min
Anatomical Dead Space (Vd)
Gas in the conducting airways (from nose to terminal bronchioles); about 150 ml.
Low alveolar ventilation =
Increase in PaC02 (partial carbon dioxide)
+ decrease in Pa02 (diffusion)
- PaC02 = most important ABG affecting ventilation
Intrapleural pressure (Ppl) affects on ventilation
- Occurs betw. 2 pleural layers
- is usually - : more - as you move up, if + lungs collapse
- (- Ppl) keeps lungs expanded, becomes more - on inspiration.
- More - @ apex b/c gravity
Apical region affect on pressure
Gravity > lung pulls down more > more - Ppl > stretch on alveoli> alveoli more expanded @ FRC
Basal region affect on pressure
Gravity less pull down> less - Ppl > alveoli less stretch > alveoli less open @ FRC (able to take more air in during FRC b/c alveoli in apex are already expanded)
Lung compliance definition
Change in volume produced by a change in pressure (C = change in V / change in P)
Low compliance
Closed alveoli OR well opened alveoli = harder to inflate (ventilate)
High compliance
Smaller alveoli = easier to inflate
Non-dependent lung region (apex)
Uppermost lung
Alveoli stretched open @ FRC b/c - Ppl
Less compliant / take in less air, decreased ventilation
Dependent lung region (basal)
Lower lung
Alveoli less stretched @ FRC, so less - Ppl
More compliant / increased ventilation
Mucus - what is it, how much is prod., what does it contain
Mechanical, bio, chem, barrier to inhaled material.
- prod. 100-250 ml/day
- covers airways, traps particles + bacteria
- 2 layers- gel/sol(cilia)
- Contains natural enzymes that destroy bacteria
Cilia
Moves particles caught in mucus up to pharynx where it is swallowed.
Stimulated by presence of mucus.
Things that - affect mucociliary clearance
Age, sleep, respiratory disease, meds, smoking
Things that + affect mucociliary clearance
Exercise, environment, meds
Cough
Functions to assist the removal of material from the airways
Used if:
- volume of mucus is too large for normal MCC
-MCC damaged
-Exercise can stimulate
Alveolar clearance
- No cilia in the alveoli
- Only small particles will reach the alveoli (i.e. tobacco, smoke)
- Deposit via sedimentation/diffusion
- Particles are engulfed by macrophages
- Takes 1-3 days
ECG - P wave
Records electrical activity thru upper chambers (atrial depolarisation)
ECG - QRS complex
Record the movement of electrical impulses thru lower chambers (ventricle depolarisation)
ECG - PR
Reflects conduction thru the AV node.
atria contracting
ECG - ST segment
Shows when the ventricle is contracting but no electricity is flowing thru.
ECG - T wave
Shows lower heart chambers are resting electrically & prepping for next muscle contraction
