Respiration Flashcards
Primary function of respiration
Efficient gas exchange
Three forms of respiration
Internal, external, cellular respiration
External respiration
Oxygen from atmosphere to blood
Internal respiration
Oxygen from blood to tissues
Cellular respiration
Oxygen usage in cells
Ventilation
Mechanical function of air in and air out
Differentiate between respiration and ventilation
Respiration is gas exchange, ventilation is entirely mechanical function of air in and out
BPM of cilia
10 times per second
Outline what the respiratory zone is
The zone where gas exchange occurs
Outline what the conducting zone is
The zone where air is conducted without gas exchange
Upper respiratory tract
From nose to larynx
Lower respiratory tract
From trachea to aveoli
What temperature does air need to be for gas exchange
37 degrees celcius
What preparation needs to happen to the air before gas exchange?
Air must be warmed, cleaned, and moistened
Three descriptors of good air for respiration
“Wet warm and sticky”
Define & locate vibrissae
Course hairs in nose, for filtration of larger particles
What tissue is the nasal & respiratory tract lined with?
Pseudo-stratified columnar ciliated epithelium with goblet cells
How does the respiratory epithelium contribute to preparing air prior to respiration?
Mucous moistens air and filters particles
Function of mucous
To moisten air and filter out particles
Three main bones in nasal cavity
Superior, middle, and inferior turbinates
Function and location of turbinates
Nasal cavity, to mix air together through turbulence
Function of rich blood supply
heating of air
All preparation steps to prepare air for respiration
Heating: blood supply
Filtration: Mucous, vibrissae, macrophages
Moistening: Mucous
How is mucous conducted down the respiratory tract?
Cilia
Where does the mucous come from?
Seromucous glands in the nasal cavity & goblet cells
How many cilia per cell?
100-300
Order the following:
Larynopharynx, nasopharynx, oropharynx
Naso/Oro/Laryno
How does the epiglottis work
Food passively closes glottis and conducts movement dodn the oesophagus. Passively moves to clear airway for conduction of air into trachea
Order the sections of the conducting zone
Trachea Main stem bronchi Lobar bronchi Segmental bronchi Smaller bronchi Bronchioles Terminal bronchioles Or: TMLSSBT --> too much lifting sends serious booty testosterone
Order the sections of the respiratory zone
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Infection becomes dangerous past what generation?
20th, into respiratory zone
Dimensions/properties of trachea
12cm long, C shaped cartilage rings, stiff, thumb thickness, trachealis
How does the oesophagus reside in relation to the trachea
Posterior/dorsal to trachea, pressed against the trachealis (soft part of trachea)
As branching in the bronchus and on wards continues, what changes to the tunnels occur
Lumen size decreases, less layers (thinner), more branching i.e. 1 - 2 - 4 - 8 - 16
Differentiate between bronchus layers and bronchiole layers
Bronchus has Pseudo-stratified ciliated, columnar epithelium with goblet cells whereas bronchioles have simple columnar/cuboidal ciliated epithelium with club cells
Bronchus has layer of exocrine mucus glands, and cartilage layer, bronchioles do not have these layers
Bronchus has mucus conveyor belt, bronchioles have water secretion
Club cells/clara cells excrete
Watery secretion, with antimicrobial enzymes
Function of smooth muscle in bronchiole wall
To constrict & dilate to alter flow of air
Acute asthma
Spasm of smooth muscle layer in bronchioles causing decreased radius of lumen and restriction of air flow.
Treatment for asthma
Adrenaline, sympathetic hormonal response etc
Are terminal bronchiole in conduction or respiratory zone
conduction
Why are respiratory bronchioles regarded as respiratory?
Because they have alveoli on them
What is a alveolar duct
Tube of alveoli
Function of alveoli
Gas exchange, external respiration
Inner wall of alveoli made of
Type one alveoli cells, squamous pneumocytes
Type ll alveoli cells function/location
inside/ish wall of alveoli, secretes surfactant
Surfactant function
To hold walls of alveoli together, prevent collapse
Alveolar macrophage function/location
Inside lumen of alveoli, breaks down any last particles
Relationship between basement membrane of type l alveolar cells and basement membrane of capillary endothelium
Fused together for efficient gas exchange
How many lobes on left lung
2
How many lobes on right lung
3
What supplies each lung segment
A tertiary bronchi
Hilum
Entry point of bronchus into lung
Why are visceral and parietal pleura stuck together, and how are they stuck together?
So that movement of the diaphragm/intercostal muscles pulls wall of lungs with it to alter volume for ventilation. They are stuck together via the serous fluid
External intercostal muscles
Actively move ribs up and out to increase lung volume and cause inhalation
When are the internal intercostal muscles in use
only active when exhale require more support (hyperventilation, lungs need to compress faster than usual).
Internal intercostal muscles
Move ribs back down and in to externally compress the lung. This causes reduced volume, and thus positive pressure to drive exhale.
Which muscles control ventilation
Expiration is internal intercostal muscles only in active exhale, inspiration is using external intercostal muscles. Diaphragm contracts to increase volume of lungs
Which way do the lungs move
Up, out, and in the other dimension
Diaphragm innervated by which nerves and which spinosegmental level
phrenic nerves, C3-C5
Intercostals innervated by which nerves and which spinosegmental level
Intercostal nerves, T1-L1
Abdominal muscles innervated by which nerves and which spinosegmental level
Thoracolumber, T7-L1
Contraction of diaphragm results in
Flattening, thus contraction of external intercostals, ribs move up and out, pleura drags lungs out with wall of thoracic cavity, inspiration
Relaxation of diaphragm results in
passive expiration, upon exercise internal intercostal muscles also contract
Phrenic nerves
Motor control of diaphragm
Thoracoabdominal nerves
Motor control of abdominal muslces
Muscles involved in ventilation
Diaphragm - contraction during inspiration
External intercostals - contraction during inspiration
Internal intercostals - contraction during active expiration
Abdominals - contraction during strenuous expiration
Inspiration occurs only when Ppul is
Negative
Ppl changes how during inspiration
Continues to get more negative
Outline a pneumothorax
Puncture of pleura, loss of negative pressure necessary for inspiration
Difference between volume and capacity
Volume is measured, capacity is calculated
IRV
Inspiratory reserve volume (volume available for inspiration in excess of tidal volume) 3100ml
ERV
Expiratory reserve volume (volume available for expiration in excess of tidal expiration) 1200ml
Vt
Tidal volume, volume used in a breath at rest
What is f representative of
Respiratory frequency, how many breaths in a minute
Ve
Minute ventilation, total volume over a minute
Ve formula
Ve = Vt * f
Vital capacity
Vt + IRV + ERV
FRC
Functional residual capacity, ERV and RV (residual volume)
RV
Residual volume
Hyperventilation
> 6L/min
Hypoventilation
<6L/min
Va
Alveolar ventilation
Vd
Deadspace ventilation - volume of non-respiatory tubules - 2.2ml/kg
How to calculate alveolar ventilation
Va=Ve-Vd
How to measure residual volume
He diffusion upon inhalation shows total volume
FEV1
Forced expiration volume (about 4L) measured over 1sec
FVC
Forced vital capacity (breath in, breath all out, this is FVC)
FEV1/FVC should be
80%
What comprises recoil force
elasticity & surface tension
Function of recoil force
Helps deflate the lung
Deflation results in what?
expiration
Define elasticity
The ability for an object to return to it’s original shape following inflation or deflation
Tissue responsible for elasticity
Parenchyma
Composition of parenchyma
Elastin and collagen
Location of parenchyma
Airway, alveoli, vessel
What is compliancy
The compliance of lung tissue to airflow
Compliance in terms of elasticity
1/elasticity
Compliance =
change in volume / change in pressure
What is surface tension
A film on top of water is an example, inter molecular forces interact to create a film with tension on top of a body of liquid
Surface tension found where in the lung
Alveoli
Direction of action of surface tension
Inwards
Why do alveoli have surface tension?
Gas/liquid border
laplaces law =
P=2T/R
Impact of radius on surface tension
Larger radius reduces pressure
Surface tension of alveoli act to do what
Deflate the lung
Why don’t alveoli collapse?
Surfactant reduces inter molecular forces
Define surfactant
Soapy liquid, secreted by type ll alveolar cells, reduces surface tension
COPD
Chronic obstructive pulmonary disease
How is COPD caused?
Pollution, smoking, surfactant insufficient
How does COPD work?
It results from a decrease in lung elasticity thus increase in compliance. This results in hyperinflation, and an increased level of inflation at FRC.
LESS ROOM FOR INSPIRATION
What is the danger of COPD?
Higher resting FRC, therefore less room for inspiration
How does fibrosis work?
Increased elasticity thus decreased compliance, due to more collagen and less elastin.
Stiff lung
Danger of fibrosis?
Shallow breathing
Where is resistance in the airway the highest? Why?
Trachea. Due to less cross sectional area
Where is resistance in the airway the lowest? Why?
Bronchioles, due to a high cross sectional area
How much more airflow occurs at the low resistance end of the lung than at the trachea?
5x
Where is airflow the fastest? Why?
Trachea, due to high resistance/pressure
Where is airflow the most turbulent? Why?
Trachea, do to high speed
Where is airflow the slowest? Why?
Bronchioles, due to large flow and low resistance
Where is airflow the most laminar/least turbulent?
Bronchioles, due to high flow, low speed
As volume of airways increase, resistance
Decreases
Outcome of parasympathetic control over respiratory system
Bronchoconstriction
Outcome of sympathetic control over respiratory system
Bronchodilation
Beta-adrenocepters
Sympathetic response, respond to noradrenaline, causing bronchodilation
Salbutamol
Beta-adrenocepter agonist
Function of mechanoreceptors in lung
To sense lung stretch, which causes firing which goes to the medulla, controlling sympathetic response to dilate bronchioles
Difference between diffusion and perfusion
Perfusion is delivery of blood to pulmonary capillaries, diffusion is movement of gas across alveolar membrane into blood stream
What does diffusion limited mean
The efficiency of gas exchange is limited by the time it takes the gas to diffuse across the membrane
What does perfusion limited mean
The diffusion of a gas across the membrane into the blood stream is so fast that what limits the rate of gas exchange is the amount of blood flow
Which gases are D limited and which are P limited
CO is D limited, and N2O & O2 are P limited
How to increase rate of diffusion in perfusion limited gas
More blood flow
Factors effecting diffusion of gas into blood stream from alveoli
Area - more area better diffusion, more alevoli more area
Thickness - 0.5micrometers, better diffusion rate
Partial pressure difference - O2 (60mmHg difference) CO2 (6mmHg difference) creates stronger driving force for diffusion
Solubility of gas - CO2, 25x more soluble than oxygen, but release time is slow so movement of both gases is the same
Molecular weight of gas
Consequences of pulmonary hypertension
Oedema, dyspnoea
Where is the apex of the lung
At the top
Pulmonary oedema reduced by
Distention and recruitment
Alveoli volume is larger in top or bottom of lung, why?
Larger, more negative pleural pressure
Is ventilation of the apex of the lung better or worse than the bottom when standing upright? Why?
Worse, more negative pleural pressure than at the base, air effected by gravity
Blood flow is better or worse at the top of the heart? Why?
Worse, lack of arterial pressure
Why is the ventilation perfusion ratio less than 1 in reality?
There is not uniform perfusion and ventilation across the lung
Why does blood flow begin in zone 2
There is sufficient arterial pressure to overcome the alveolar pressure
How does pulmonary arterial pressure impact resistance?
Higher pressure results in decreased resistance, as distention and recruitment occurs
Outline sheetflow
Sheet like structure of capillary walls increases contact of membrane with alveolar membrane
Why is there less blood flow in the top of the lung
Because the R.V. mean pressure does not generate enough force to push the blood to the top, so alveolar pressure is greater than arteriole and venous pressure
Why is zone 3 the best for blood flow
Because arterial pressure is greater than venous pressure, but venous pressure is greater than alveolar pressure
Why are O2 levels higher at the top of the lung?
Lots of blood flow takes up oxygen at bottom, low blood flow at top so no O2 being removed
Why are O2 levels higher at the top of the lung?
Lots of blood flow takes up oxygen at bottom, low blood flow at top so no O2 being removed
Average tidal volume
500ml
Formula for perfusion
Q= HR * SV
Average stroke volume of heart
70ml
Outline pulmonary hypertension
Right heart failure, hypoxic lungs, vasoconstriction, increased pressure, oedema
Outline pulonary oedema
L.V. failure, back log of blood, increased pulomary venous pressure, oedema
Sympotm of oedema
Dyspnoea (breathlessness)
O2 is stored how
Bound to Haemoglobin and dissolved in plasma
Hb is
Haemoglobin
Outline Hb
Polypeptide, 4 binding sites (haem moietys) found in erythrocytes
Allosteric effect
Twisting of haemoglobin to expose haem moeity
Why is the O2 dissociation curve not linear?
Do to the co-operative binding of O2 to haemoglobin
Shape of O2 curve name
Sigmoidal relationship
How much of blood O2 does tissue take
25%
Why does O2 detach from haemoglobin
As PO2 drops, the affinity between haemoglobin and O2 declines, so it is released into the tissues
What causes a decrease in O2 affinity for haemoglobin?
More: temperature, CO2, DPG, H+
What impact does pH have on O2 affinity of haemoglobin?
H+ ions cause dissociation of O2 from haem moiety
Oxyhaemoglobin?
Fully saturated haemoglobin
Differ between content and saturation of O2
Content is how much you have, saturation is how many (/4) O2 molecules a haemoglobin has
Outline a left shift
Lower temperature, less CO2, fewer H+ ions, less DPG, thus higher affinity of haemoglobin to O2, and less tissue content of O2
Outline the Bohr effect
Higher temperature, more CO2, more H+ ions, more DPG, thus lower affinity of haemoglobin to O2 and more release into tissues.
Outline fetal haemoglobin and it’s purpose
Left shifted, needs higher O2 affinity to transport O2 from placenta to embryo
Outline myoglobin and it’s purpose
Very left shifted, extremely high O2 affinity, used as an O2 storage molecule
How is CO2 transported in blood?
- Dissolved in solution
- As HCO3-
- On an amine group of Hb
- As H2CO3
Percentage of CO2 in blood vs plasma
70% in RBC
30% in plasma
How much of CO2 is bound to haemoglobin
5%
Where is CO2 affinity highest?
Venous blood
Where is CO2 affinity lowest?
Arterial blood
Outline the haldane effect
Difference between affinity for CO2 at venous and at arterial levels. Higher affinity at lower PCO2 means better tissue loading of CO2 into venous return blood
Anoxia
Low O2
Asphyxia
O2 deprivation
Hypercapnia
High CO2 levels
Hypocapnia
Low CO2 levels
Hyperventilation and CO2 levels
Fast hard breathing (causes hypocapnea thus vasoconsrtiction at cerebellum)
ischaemia
Low blood supply to tissues
Apnoea
No breathing
Dyspnoea
Breathlessness
Role of central chemoreceptors
To sense H+ ions from CO2 + H2O reaction, senses hypercapnia and increasing ventilation
Location of central chemoreceptors
Medulla
Role of peripheral chemoreceptors
To sense hypoxia, hypercapnia, acidosis, haemorrhage, sympathetic activity and sodium cyanide
Location of peripheral chemoreceptors
Corotid arterial bifurcation
Speed of P.C.R vs C.C.R
Peripheral are within a breath or two, Central are slow as the only measure hypercapnia
Ondines curse
Central chemoreceptors do not work
Dalton’s law
Sum of all partial pressures is the total air pressure
Hyperventilation physiology
More CO2 is breathed off than created
Elevated pH
Physiology of hypoventilation
Less perfused O2 and more CO2 in blood
