Respiratory 1 Flashcards
Mastery (23 cards)
Functions of the Respiratory
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Air Passages
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- System
- Gas Exchange
- Acid-Base balance
- Thermoregulation
- Immune function
- Vocalization
- Enhances venous return
- Mouth / Nose
- Pharynx
- Larynx
- Trachea
- Bronchi
- Bronchioles
- alveoli
Alveoli
Type I Alveolar cells
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Type II cells
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* ↓
Macrophages
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Type I Alveolar cells
- Make up the wall
Type II cells
- Secrete surfactant
* ↓ surface tension
Macrophages
- Immune function
Bronchioles
what can they do? control? muscle?
Alveoli
site of? wall? surface area? contain what? pores of … connect… ? Help to what?
AFTER
AFTER
Respiration
Ventilation
External Respiration
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Gas Transport
Internal Respiration
-
Pressure Relationships in the Thoracic Cavity
Atmospheric (air) pressure (Patm)
… mm Hg at sea level
Respiratory pressures are relative to Patm
Alveolar pressure
Pleural pressure
Bronchoconstrict or dilate
Control air flow
Smooth muscle
Site of Gas Exchange
Thin-walled
Large surface area for diffusion (75 m2)
contain fine elastic fibres
Pores of Kohn connect adjacent alveoli
Helps equalize air pressure
AFTER
AFTER
Ventilation
External Respiration
- Gas exchange between alveoli and blood
Gas Transport
Internal Respiration
- Gas exchange between blood and tissues
Atmospheric (air) pressure (Patm)
760 mm Hg at sea level
Respiratory pressures
are relative to Patm
Alveolar pressure
Pleural pressure
Pressures:
Atmospheric pressure
*
Intra-alveolar pressure
*
Intra-pleural pressure
*
Transpulmonary pressure
*
Pulmonary Ventilation
what is it and what does it depend on
Volume changes →
Pressure changes →
Atmospheric pressure
* air
Intra-alveolar pressure
* in alveoli
Intra-pleural pressure
* Pleural space
Transpulmonary pressure
* difference between intra-pleural pressure (Pip) and intra-alveolar pressure (Palv)
Pulmonary Ventilation
Mechanical processes depend on volume
changes in the thoracic cavity
Volume changes → pressure changes
Pressure changes → gases flow to equalize
pressure
BOYLE’s LAW
Quiet Inspiration
…. muscles contract, which ones
Thoracic volume … then…
Intrapulmonary pressure … then…
… its pressure gradient, until … = …
AFTER
Forced Inspiration
Recruit … and ….
Greater … in thoracic volume
Larger …. in thoracic pressure
… pressure gradient
More air flow…
(if volume ↑, then pressure ↓)
Quiet Inspiration
Inspiratory muscles contract
* Diaphragm and external intercostals
Thoracic volume ↑
Lungs stretch
Intrapulmonary pressure ↓
Air flows into the lungs
* down its pressure gradient, until Ppul = Patm
AFTER
Forced Inspiration
Recruit Scalenus and sternocleidomastoid
Greater ↑ in thoracic volume
Larger ↓ in thoracic pressure
Larger pressure gradient
More air flow in
Quiet Expiration
… process
Inspiratory muscles …
Thoracic cavity volume …
* lungs…
increase in…
Air flows….
Forced Expiration
Recruit … and …
Larger … in thoracic volume
* Larger …. in thoracic pressure
…. gradient
* More air flow ….
Passive process
Inspiratory muscles relax
Thoracic cavity volume decreases
* Elastic lungs recoil
increase in alveolar pressure
Air flows out of the lungs
Recruit Abdominals and internal intercostals
Larger decrease in thoracic
volume
* Larger increase in thoracic
pressure
Larger gradient
* More air flow out
Control of Ventilation
Involves
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Respiratory centres in brain stem establish a….
Medullary respiratory centre
* Dorsal respiratory group (DRG)
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* Ventral respiratory group (VRG)
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Pre-Bötzinger complex
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Apneustic centre
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Pneumotaxic centre
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- Chemoreceptors monitoring blood gases
- Inputs to neurons in the reticular formation of the medulla and pons
Respiratory centres in brain stem establish a rhythmic breathing pattern
Medullary respiratory centre
* Dorsal respiratory group (DRG)
⬧ Mostly inspiratory neurons
* Ventral respiratory group (VRG)
⬧ Inspiratory neurons
⬧ Expiratory neurons
* Receive input from chemoreceptors
Pre-Bötzinger complex
* Generates respiratory rhythm
Apneustic centre
* Prevents inspiratory neurons from being switched off
⬧ Provides extra boost to inspiratory drive
Pneumotaxic centre
* Sends impulses to DRG that help “switch off” inspiratory neurons
⬧ Dominates over apneustic centre
Peripheral Chemoreceptors
Carotid bodies are located in …
Aortic bodies are located in…
Monitors…
Respond to
↑, ↑, or ↓↓↓
Carbon Dioxide and H+
CO2 and water combine….
If CO2 …, …. H+
Affect …. of the body
Central Chemoreceptors
In …
Monitors….
Sensitive to changes in ↑ , via
Peripheral Chemoreceptors
Carotid bodies are located in the carotid sinus
Aortic bodies are located in the aortic arch
Monitors blood
Respond to ↑ H, ↑ CO2, or ↓↓↓ O2
Carbon Dioxide and H+
CO2 and water combine in the body to make CARBONIC ACID
If CO2 increases, so does H+
Affect pH of the body
Central Chemoreceptors
In Medulla (respiratory centre)
Monitors cerebrospinal fluid
Sensitive to changes in ↑ H+, via ↑ CO2
- Trigger for Inspiration
- ? metabolism leads to ? CO2 and ? O2
- ? CO2 converts to ? H+
- CO2 and H+ in blood triggers …
- CO2 crosses …. and converts to …, which triggers…
- Input goes to…
- Triggers …
- Inspiratory muscles … for inspiration
- ↑ metabolism leads to ↑ CO2 and ↓ O2
- ↑ CO2 converts to ↑ H+
- CO2 and H+ in blood triggers peripheral
chemoreceptors - CO2 crosses blood-brain barrier and converts to H+, which triggers central chemoreceptors
- Input goes to Respiratory Centre
- Triggers inspiratory neurons
- Inspiratory muscles contract for inspiration
Role of Oxygen
O2 is … a significant factor in …
BUT - if O2 levels drop below … – then it …
Eg.
Depth and Rate of Breathing
Hyperventilation
- increased
- High removal of …
Causes … levels to decline (resulting in…)
* Lose “….” for inspiration
⬧ Longer …. possible
* May cause … and ….
O2 is NOT a significant factor in normal control
of breathing
BUT - if O2 levels drop below 60 mmHg – then it does become a factor
Eg. High altitude
Hyperventilation
- increased depth and rate of breathing
- High removal of CO2
- Causes CO2 levels to decline (hypocapnia)
* Lose “trigger” for inspiration
⬧ Longer breath holds possible
* May cause cerebral vasoconstriction and cerebral
ischemia
Summary of Chemical Factors
…. is the most powerful respiratory stimulant
If arterial Po2 < …, it becomes the major stimulus
Eg.
… arterial H+ (eg. Lactic acid) also act as a…
↑ CO2 is the most powerful respiratory stimulant
If arterial Po2 < 60 mm Hg, it becomes the major stimulus
Eg. High altitude
↑ arterial H+ (eg. Lactic acid) also act as a
respiratory stimulant
Influence of Higher Brain centres
Hypothalamus / limbic system
- modify … and … of respiration
Example:
… body temperature acts to … respiratory rate
… controls bypass … controls
Example: voluntary breath holding
Hypothalamus / limbic system
modify rate and depth of respiration
Example: breath holding that occurs in anger or
gasping with pain
↑ body temperature acts to ↑ respiratory rate
Cortical controls bypass medullary controls
Example: voluntary breath holding
Control of Respiration - Reflexes
Hering-Breuer reflex
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* Signals the….
* … response
Pulmonary Irritant Reflex
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* Reflex constriction of …
* eg. … , …
Receptors in the larger airways … the cough and
sneeze reflexes
Nonrespiratory Air Movements
Most result from ….
Examples include:
1, 2 , 3, 4, 5, 6
Hering-Breuer reflex
Stretch receptors triggered to prevent overinflation of the lungs
* Signals the end of inhalation and allow expiration to occur
* Protective response
Pulmonary Irritant Reflex
Receptors in the bronchioles respond to irritants
* Reflex constriction of air passages
* eg. Asthma, allergies
Receptors in the larger airways mediate the cough and
sneeze reflexes
Nonrespiratory Air Movements
Most result from reflex action
Examples include:
Cough
Sneeze
Crying
Laughing
Hiccups
yawns
Respiratory Adjustments: EXERCISE
- Increased … production and … consumption
- … gradients for …
- … diffusion
Other factors that contribute to higher breathing
- … - … of exercise
* Cortical activation of muscles and respiratory centre
- … feedback from muscles
- … body temperature
- … blood lactic acid and CO2 levels
- … epinephrine
Physical Factors Influencing Pulmonary Ventilation
Four factors
AFTER
Airway Resistance
Relationship between flow (F), pressure (P), and
resistance (R):
F = Change in…
… is the biggest determinant
P - pressure gradient between…
- Increased CO2 production and O2 consumption
- Larger gradients for gas exchange
- Faster / greater diffusion
- Other factors that contribute to higher breathing
- Psychological - anticipation of exercise
- Cortical activation of muscles and respiratory centre
- Sensory feedback from muscles
- Higher body temperature
- Higher blood lactic acid and CO2 levels
- Higher epinephrine
FOUR FACTORS
- Airway resistance
- Alveolar surface tension
- Lung compliance
- Elastic Recoil
AFTER
Airway Resistance
Relationship between flow (F), pressure (P), and
resistance (R):
F = Change in P / R
Radius of bronchioles is the biggest determinant
P - pressure gradient between atmosphere and
alveoli
Airway Resistance
Asthma
Severe … or … of bronchioles
* Prevents …
Epinephrine ……
Eg. …
Eg. …
Asthma
- Severe constriction or obstruction of bronchioles
* Prevents ventilation
Epinephrine dilates bronchioles and reduces
air resistance
Eg. exercise
Eg. Epi pen with allergy response
Alveolar Surface Tension - Surface tension
- … liquid molecules to one another at a …. interface
- … any force that tends to increase the
surface area of the liquid
Surfactant
- what is it and what is it produced by
… surface tension of alveolar fluid
* discourages … collapse
Premature infants
* … surfactant
* respiratory …
- Attracts liquid molecules to one another at a
gas-liquid interface - Resists any force that tends to increase the
surface area of the liquid
Surfactant
- Detergent-like lipid and protein complex produced by type II alveolar cells
↓ surface tension of alveolar fluid
* discourages alveolar collapse
Premature infants
* ↓ surfactant
* respiratory distress
Lung Compliance
- what is it
- change in … with a given change in pressure
- Relates to … required to distend the lungs
Normally high due to
-… of the lung tissue (connective
tissue)
- Alveolar …
Lung Compliance
Diminished by
- Nonelastic … tissue (eg)
- … production of …
- Decreased … of the thoracic cage
* eg. …. of respiratory muscles
- Expandability of the lungs
- change in lung volume with a given change in pressure
- Relates to effort required to distend the lungs
- Normally high due to
- Distensibility(Extension) of the lung tissue (connective
tissue) - Alveolar surface surfactant
Diminished by
- Nonelastic scar tissue (fibrosis)
- Reduced production of surfactant
- Decreased flexibility of the thoracic cage
* eg. Paralysis of respiratory muscles
Elastic Recoil
- How the lungs …..
- Help lungs return….
Depends on two factors
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- How the lungs rebound after being stretched
- Help lungs return to their pre-inspiratory volume
Depends on two factors - Connective tissue in the lungs
- Elastin / Collagen
- Alveolar surface tension
- Increases tendency of alveoli to recoil
description and average value
Lung Volumes to remember
Tidal Volume –
Vital Capacity -
Reserve volumes –
* Inspiratory – , Expiratory –
Residual Volume –
Tidal Volume – air moved on a quiet breath
Usually about 500 mL
Vital Capacity
Maximum air you can move - ~ 5 or 6 L
Reserve volumes – extra air that can be
added to either inspiration or expiration if
the breath is deeper
* Inspiratory – 3L, Expiratory – 1 L
Residual Volume – air left in lungs - ~1200
mL
Dead Space
- what is it
Anatomical dead space
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Alveolar dead space
-
AFTER
Pulmonary Function Tests
Minute ventilation
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Forced vital capacity (FVC)
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Forced expiratory volume (FEV)
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- inspired air that doesn’t contribute to gas exchange
Anatomical dead space
- volume of air passageways (~150 ml)
Alveolar dead space
* alveoli with no gas exchange due to collapse or
obstruction
AFTER
Pulmonary Function Tests
Minute ventilation
total amount of gas flow into or out of the respiratory tract in one minute
Forced vital capacity (FVC)
gas forcibly expelled after taking a deep breath
Forced expiratory volume (FEV)
the amount of gas expelled during specific time intervals of the FVC
