Respiratory Physiology Flashcards
Respiration controls…
- CO2 supply
- O2 supply
- H+ ion concentration
What is the outer form of respiration?
- Gas exchange: outside world → Blood
- Take-up + transmission of oxygen by cells
- CO2 elimination
- Gas exchange
Inner form of respiration
Gas exchange: Blood → Cells
99% of pulmonary blood supply comes from…
A. pulmonalis
99% blood leaves the lung via…
Vv. pulmonales → Left atrium
Which vessels represent the ‘dual blood supply’ of lung circulation?
- A. pulmonalis (Functional)
- A. bronchiales (Nutritive)
1% of pulmonary blood supply comes from…
Aa. bronchiales (Oxygenated)
Venous blood contaminates refreshed blood via …
V. bronchiales
What transfers deoxygenated blood from the right ventricle to the lung?
A. pulmonales
From the aorta, …transfers oxygenated blood to the lungs
A. bronchiales
Automatically decreased perfusion to certain areas of the lung leads to…
Redirection of blood to well-ventilated lung territories
Describe the physiology of blood redirection in the lung
Hypoxia causes vasoconstriction
A small portion of blood goes directly to the right atrium via…
V. azygos
Where does venous blood contaminate oxygenated blood?
- V. bronchiales
- Coronary vessels
Blood stays in the capillaries for…during 1 cardiac cycle
800 msec
O2 and CO2 diffusion takes how long to occur?
250 msec
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pO2 (mmHg)
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pCO2 (mmHg)
Unit for airflow
Va/min
(Ventilation, litre air/ min)
Airflow is proportional to…
Perfusion of blood
Unit for perfusion of blood (Q)
litre/min
Normally: Va/Q =
1
In normal conditions, blood will flow away…
Arterialised (oxygenated)
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When the alveolus is plugged…
- Va = 0
- Va/Q = 0
- Blood flows away deoxygenated
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Capillary plug
When blood flow stops
In the incidence of capillary plug…
- Q=0
- Va/Q = ∞
- Alveolar gas pressure = atmospheric pressure
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Degree of perfusion
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Perfusion absent
Degree of perfusion
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Perfusion is sporadic
Degree of perfusion
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Perfusion is constant
Describe the effects of gravity in zone 1 of the lung
- Pressure in alveoli compresses blood vessels
- Perfusion decreases
- PA > Pa> Pv
Describe the effects of gravity in zone 2 of the lung
- Alveolar capillaries are open during systole
- Closed during diastole
- PA>Pa>PV
Describe the effects of gravity in zone 3 of the lung
- Gravity increases BP
- Alveolar pressure can’t compress capillaries
- During diastole and systole
- PA>PV>Pa
PA=
Alveolar pressure
Pa=
Arterial pressure
PV=
Venous pressure
Which innervation causes pulmonary vessels to enlarge
Parasympathetic (n. vagus)
Which innervation causes pulmonary vessels to constrict?
Sympathetic, noradrenergic fibres
(Through α-receptors)
Effect of adrenalin on pulmonary circulation
- Creates intensive alveolar dilation (through β-receptors)
- Increased ventilation
- Crucial for anaphylaxis counteraction
Local hypoxia in the lungs causes…
Local stenosis → Blood redistribution
The effect of BP increase on pulmonary circulation
- Decreased vascular tone
- Affects the ability to achieve extremely high minute volume
How does the nasal ciliated cylindrical epithelium + blood vessels play a role in organism defence?
- Mechanically:
- Mucous motion
- Coughing
- Immunologically
- IgA
How does the nasal ciliated cylindrical epithelium + blood vessels play a role in air conditioning?
- Saturates inspired air with water vapour
- Warms up the air
What is the defensive function of the pharynx?
- Mucous layer
- Lymphatic vessels + glands
Lower respiratory tract
- Trachea, its branching and the lungs
- Function: Filtering and protection
Epithelium found in the lower respiratory tract
Pseudostratified ciliated columnar epithelium
Contains goblet cells
Goblet cells produce…
Mucine - IgA
Cilia of the epithelium are moving in…
Sol phase
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Terminal bronchiolus
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- Bronchiolus* respiratorius
- Respiratory epithelium appears
Give the layers (alveolar) between blood and atmospheric air
- Surfactant layer
- Alveolar layer
- Membrana basalis
- Capillary endothel
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The alveolar wall is built up of which pneumocytes?
- Epithel → Provides gas exchange
- T2 → Produce surfactant layer
Muscles involved in inspiration
- Diaphragm
- External intercostal muscles
- Abdominal muscles
Function of mm. intercostales externi
- Raise ribs, assist inspiration
- Parietal region of the diaphragm can dilate easier
The collapsing tendency of the lung is due to…
- The surface tension of alveoli
- Elastic elements of the lung
Total collapse of the lung is prevented by…
Fluid-film between:
- Visceral pleura
- Parietal pleura
Pause of respiration
The retractive force of lung balanced with the tension of muscles and joints of the chest (rest)
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Rate of respiration is dependent on…
Metabolic activity
Inspiration or expiration?
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Inspiration
Inspiration or expiration?
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Expiration
What do the blue lines represent?
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Tendon-lamella
Collapsing tendency of the lungs reduces…
Lung volume during expiration
Title the figure
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The mouse-elephant curve
Which air-flow types are observed in panting?
- Parietal
- Central
What kind of gas exchange occurs during panting?
Physiological gas exchange
- Slight change in gas pressure
During panting, parietal gas exchange is…
Slow
Central gas stream
- Fast
- Heat exchange
- Stimulates water release in mouth
Panting in species other than canines would cause…
- Loss of CO2
- Alkalosis
The spirometer measures…
Volume changes and air fractions of breathing
Ventilation
- The quantity of air entering and leaving the lung
- Per unit time
In the spirometer, the height of the upper cylinder indicates…
The size of the given volume fraction
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Inspiratory Reserve Volume
(IRV)
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Tidal volume
(TV or VT)
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Expiratory Reserve Volume
(ERV)
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Residual Volume
(RV)
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Inspiratory Capacity
(IC)
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Functional Residual Capacity
(FRC)
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Vital Capacity
(VC)
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Total Lung Capacity
(TLC)
VC =
VT + IRV + ERV
The deepness of inspiration increases…
- The proportion of fresh air : used air
- Measured with Ventilation coefficient
Ventilation coefficient
Vcoeff = fresh/used
Volume dead
- Anatomical + physiological dead-space
- Doesn’t contribute to gas exchange
What contributes to anatomical dead space?
- Air fraction of:
- Upper respiratory tracts
- Lower respiratory tracts
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What contributes to the physiological dead space?
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- Occluded alveoli
- Alveoli excluded from circulation
Used air =
FRC + VD
Fresh air =
VT - VD
Pressure change in the pleural cavity
Intrapleural pressure
Pressure change in the lung
Intrapulmonar pressure
Intrapleural pressure is always…
Negative
Why is the intrapleural pressure always negative?
Gases constantly being absorbed by tissue
Formula for transpulmonary pressure
Ptp = Palv - Ppl
During apnea, pulmonary pressure is equal to…
Atmospheric pressure
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Pulmonary pressure
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Intrapleural pressure
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Volume
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Apnea
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Inspiration
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Expiration
Müller’s experiment
- Deep inspiration with a closed epiglottis
- Pulmonary and intrapleural pressure decreases
Valsava experiment
- Forced expiration with closed epiglottis
- Pulmonary + Intrapleural pressure increase
Used to equalise pressure in the ear
Pneumothorax
- Loss of intrapleural negative pressure
- Small: Escaped air can be reabsorbed from the pleural cavity
- Large: Air needs to be drawn out of the pleural cavity
Closed pneumothorax
- Small hole in thoracic wall/lung
- Air gradually absorbed, IP pressure returns
Open pneumothorax
- Large hole
- IP is atmospheric
Valvular/tension pneumothorax
- Flap of tissue acts as a valve over the hole
- Allows air entry during inspiration
- Doesn’t allow escape during expiration
- Lung severely collapses
Emphysema
- Septa between alveoli are damaged
- Reduced respiratory surface
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Resistance forces which need to be overcome during inspiration
- Friction
- Non-elastic tissue resistance
- Total elastic resistance
Friction force effect on inspiration
- Smallest force of resistance
- Caused be turbulent air flow
Non-elastic tissue resistance during respiration
- Caused by:
- Diaphragm
- Chest
- Abdominal structures
Total elastic resistance of inspiration
- Stretch of vertebral + costal joints
- Retractive forces
- Resistance of interstitial elastic elements
- Surface tension in the alveoli (Strongest)
Surface tension
- Cohesive forces
- Internal pressure
- Causes liquid surfaces to contract to minimal area
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Forces causing the collapse of alveoli
- Retractive tendency of elastic elements
- Surface tension
Forces acting against collapse of alveoli
- Actual intrapulmonary pressure
- Surface tension of neighbouring alveoli
- Presence of surfactant
The result of alveolar dilating and retracting forces…
Transpulmonary pressure
The open state of alveoli can be maintained only by…
Materials reducing surface tension
DPPC
- Reduces surface tension
- If not present:
- Fatal alveolar collapse
- Plasma filtrated into alveoli (Reduced diffusion)
DPPC deficiency occurs genetically in…
- Calves
- Causes early postnatal death
How does lack of DPPC cause death?
- Intrapleural pressure higher (30mmHg)
- Alveolus cannot stay open against larger wall tension
delta V / delta P =
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Compliance
Compliance
The ability of a hollow organ to change its volume
Figure showing compliance in the lungs
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Surfactant layer during inspiration
- Thicker
- Lower number of DPPC on air-liquid interface
- Only molecules on the surface can display tension-reducing effect
As the alveolus expands, DPPC…
- Can act on a larger surface area
- Surface tension gets smaller
Smaller changes in pressure may result in…
High unit volume changes
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DPPC max
- DPPC molecules used up
- Further volume increase requires exponential pressure increase
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Amount of DPPC on the alveolar surface
Changes in volume depend on…
DPPC availability in the alveoli
Surfactant is produced by…
Type II alveolar cells
Respiratory gas exchange is determined by…
- Partial pressure
- Diffusion conditions
- Surface size
- Metabolic activity (O2 consumption)
Dalton’s law
- Calculate partial pressure
- P/Ptotal = V / VT
Henry-Dalton’s law
- Expresses how a gas is diluted in fluid
- C = alpha x P
- STPD
- BTPS
- Standard temperature and pressure
- 760mmHg
- 0°C
- Free of water vapour
- Body temperature and pressure
- 760mmHg
- 37°C
- Saturated with water vapour
Partial pressure
Measure of how much gas is present
Partial pressure of oxygen in the air
160 mmHg
DCO2 =
20 x DO2
What binds 70x less O2 than the blood?
Plasma
Average O2 consumption of animals
300 mlO2/min/100kg
O2 consumption rate during forced physical performance
6000 mlO2/min/100kg
1 Hb binds … O2
4
Speed of haemoglobin saturation
10 msec
Factors affecting haemoglobin O2 affinity
- Body temp
- Partial pressure CO2
- 2,3-DPG concentration
- pH
- CO
- Myoglobin
Oxygen saturation curve shape
Sigmoidal
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Why is O2 saturation curve sigmoidal?
- The binding of the first O2 facilitates the next
- By allosteric stimulation
Normal arterial and venous blood saturation %
A: 95%
V: 75%
A shift to the right of the O2 saturation curve can be caused by…
- Increase pCO2
- Increased pH
- Increased Temperature
- Increased 2,3-DPG
What is shown in the figure?
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Change of O2 affinity of hemoglobin by pCO2 change
What is shown in the figure?
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Change of O2 affinity of hemoglobin by pH change
Bohr shift
- Decreased CO2 → pH increase
- Haemoglobin picks up more oxygen
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What is shown in the figure?
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Change of O2 affinity of hemoglobin by temperature change
What is shown in the figure?
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Change of O2 affinity of hemoglobin by 2,3 DPG change
Describe the effect of 2,3-DPG increase
- By-product of 2,3-DPG displaces O2 from Hb
- Saturation curve shifts to the right
- More O2 is given to the tissues
Embryonic haemoglobin is less capable of binding…
2,3 DPG
- Affinity is higher than maternal blood
- Embryo can easily get O2 from the mother’s blood
CO binding is…
Irreversible
Change of O2 affinity of hemoglobin by myoglobin change
Non-sigmoidal curve
- Myoglobin takes O2 from Hb, storing it in the muscle
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The fate of CO2 when it enters the capillary
- Converted to bicarbonate (with carbonic anhydrase)
or
- CO2 present in the blood:
- Physically dissolved
- Protein-bound
All form an equilibrium
H+ produced when CO2 enters the blood is bound by…
Deoxihemoglobin
Water + CO2
H2O + CO2 → HCO3- + H+
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If haemoglobin is not deoxygenated by the tissues…
Removal of CO2 is damaged
RBC membrane is impermeable to…
K+
Describe the function of capnophorine transporter
- Exchanges bicarbonate to chloride
- Ensuring electroneutrality
Significant increase in IC Cl- concentration caused by capnophorine leads to…
Hamburger shift
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Cl- transport into the RBC causes
- Simultaneous intracellular H2O migration
- Causes cell volume increase
What provides the buffer-base effect of blood?
- Deprotonated hemoglobin
- Bicarbonate in the plasma
Haemoglobin buffer (Tissue)
Deoxyhaemoglobin produced → H+ acceptor
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Haemoglobin buffer (Lung)
- H+ released from deoxyhaemoglobin
- Oxyhaemoglobin created at lung-level
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Carbamino haemoglobin (tissue)
- From CO2 binding haemoglobin
- H+ dissociates
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Carbamino haemaglobin (Lung)
- CO2 released from carbamino haemoglobin
- Deoxyhaemoglobin uptakes H +
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Title the figure
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CO2 dissociation curve
- Shows quantity of CO2 transported in the blood
- As a function of pCO2
The haldane effect
- Increased pO<span>2</span> → Decreased chemically bound CO2
- High oxygen tension stimulates CO2 release
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CO2 concentration in arterial blood
22.1 mmol/l
CO2 concentration in venous blood
24.4 mmol/l
What is detected during breathing regulation?
Gas tensions of blood
Effect of severing: Above the pons
- [1]
- No effect
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Effect of severing: Middle of the pons
- [2]
- Deep inspirations
- Inspiration-inhibiting centre cut
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Effect of severing: Border of pons and medulla oblongata
- [3]
- Deeper + Shallow breathing
-
Apneustic centre
- Responsible for normal rhythm
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Effect of severing: Medulla above the exit point of n. phrenicus
- [4]
- Respiratory cycle stops
- Autonomous respiratory group cut
- DRG (Dorsal respiratory group)
- VRG (Ventral respiratory group)
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Effect of severing: below the exit point of n. phrenicus
- [5]
- No change is respiration
- Respiration regulating groups located above this point
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Effect of cutting n. vagus
Deep inspiration, sudden expiration
Hering-breuer reflex
- Inspiration inhibiting reflex
- Stretch receptors detect stretching
- DRG centres recieve afferentation via n. vagus
- Stimulates VRG
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Which afferent nervous factors other than Hering-Breur influence respiration?
- Emotional changes
- Hyperventialtion
- Pain
- Sleeping
- Baroreceptor-related circulatory/ respiratory reactions
Efferent nervous respiratory signals run to the…
Respiratory muscles
Efferent stimulation of inspiration
- Stimulation of respiratory muscles
- Expiratory muscles inhibited
- N. phrenicus stimulated
Efferent stimulation of expiration
- Normally passive
- Inspiratory muscles inhibited
- Expiratory muscles stimulated
Which is more important:
- Peripheral reception
- Cenral reception
Central reception
Location of the highest sensitivity to
- pCO2 of blood and CSF
- pH
- The bottom of the IVth ventricle
- Influences the DRG (inspiratory)
How does CO2 stimulate DRG activity?
- CO2 → CSF
- pH drop → DRG activity stimulated
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Receptors of peripheral reception are located…
- Glomus caroticum (Carotid body)
- Glomus aorticum (Aortic body)
Glomus caroticum
- Cluster of chemoreceptors
- Found at bifurcation of the carotid artery
Glomus aorticum
- Chemoreceptors and baroreceptors
- Located along the aortic arch
Peripheral reception is sensitive to…
pO2
Secondary protective mechanism
- By peripheral reception
- pO2 reception
- Generates hyperventilation
Breathing type
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Normal
Breathing type
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Biot
- Long apnea
Breathing type
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Cheyne-Stokes
- Characteristic periodicity
Breathing type
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Kussmaul
- Found in uremia and diabetic coma
Normal breathing
- Steady inspiration + Expiration
- Uniform depth
Dyspnea
Random breathing
List the defensive respiratory reflexes
- Sneezing
- Coughing
- Nociceptive apnea
- Diving reflex
- Combined swallowing reflex
Sneezing
- Mechanical/chemical irritation of upper respiratory tract
- Speed: 300 m/s
Coughing
- Tracheo-bronchial irritation
- Mechanism similar to sneezing
Nociceptive apnea
- Prevents inhilation of gases or fumes
- Sudden apnea
- Same may happen for pain or cooling sensation
Diving reflex
- Water in contact with the head
- Breathing motions inhibited
- Protection from inspiration of water
Combined swallowing reflex
- Foot touches pharyngeal wall
- Apnea → prevents choking
Birds ventilate their lungs by expanding…
Their air sacs
The cranial group of air sacs contain…
Used air
The caudal group of air sacs contain…
Fresh air
Mechanism of air sacs
- Inhalation 1: Caudal air sacs fill
- Exhalation 1: Caudal air sacs empty, lungs fill
- Inhalation 2: Cranial air sacs fill
- Exhalation: Cranial air sacs empty
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Benefit of the avian breathing cycle
- Continuous gas exchange
- Continuous respiration
- Allows higher energy level than mammals
The finest branches of the avian bronchial system
Parabronchi
- Allows air to flow through unlike mammalian alveoli
Countercurrent flow in the lung
- Allows gas exchange
- Air and the blood flow to eachother
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The lower gas-exchange capacity of bovines is a predisposing factor for…
Broncho-alveolar hypoxia
Broncho-alveolar hypoxia reduces…
Pulmonary clearance rate
Relatively higher air-exchange activity increases the risk of…
Pulmonary infectinon