Unit 2.1: Ventilatory System Flashcards
What is Homeostasis?
The maintenance of internal environment between a specific and constant range
How do Pulmonary & Cardiovascular System Work Together?
To maintain oxygen content in blood
What are principal structures of ventilatory System?
Conducting Airways:
- Nose, Mouth, Pharynx, Larynx, Trachea, Bronchi, Bronchioles
Gas Exchange:
- Lungs & Alveoli
Functions of Conducting Airways
- Low resistance pathways for airflow
- Defence against harmful substances (cilia, macrophage cells, Mucus)
- Warms and moistens air through lining of airways
What is cilia and what does it do?
Tiny hairs which filter air and traps present particles, stopping them from entering lungs and causing infection.
What are macrophage cells and what do they do?
Cells lining conducting airways which serve as defense against foreign bodies.
What are the two functions of mucus?
Trap particles & pathogens but also improves gas exchange
What is Pulmonary Ventilation and its Acronym?
PV = Inflow and outflow of air between atmosphere & lungs (breathing)
What is Total Lung Capacity and its acronym?
TLC = Volume of air in lungs after a maximum inhalation
What is average TLC in adults (male & female)?
6L for males & 4.2L for females
What is TLC = to?
Vital Capacity (VC) + Residual Volume (RV) = TLC
What is Vital Capacity and its acronym?
VC= Maximum volume of air that can be exhaled after maximum inhalation (Taking deep breath in & blowing it all the way out)
What is Residual Volume and its Acronym?
RV = Volume of air still contained in lungs after maximum exhalation (Blowing out as hard as you can: remaining air is RV)
Why is RV important? What percentage of lung capacity does it represent?
Prevents lungs from collapsing during forced breathing
Is 20% of Total Lung Capacity
What is Tidal Volume and its acronym?
TV = Volume of air breathed in & out in one breath during normal breathing
What is the normal range of TV? What percentage of the TLC does it make up?
Normal range is 500ml
Makes up 7-8% of TLC
What is Expiratory Reserve Volume and its acronym? What percentage of the TLC does it make up?
ERV = Additional air over tidal volume that can be exhaled forcibly (Exhale forcibly & push all air out that you possibly can)
Makes up 20% of TLC
What is Inspiratory Reserve Volume and its acronym? What percentage of the TLC does it make up?
IRV = Additional inspired air over tidal volume (Make normal tidal inspiration, take a deep breath all the way in)
Makes up 60% of TLC
What is vital capacity equal to? VC = … + … + …
TV + IRV + ERV = VC
How does ventilation work when at rest?
- Constant & predictable
- Rate & Depth of breathing are automatic (no conscious imput required)
- Breathing takes place place thanks to pressure gradients (air moves from areas of high pressure to regions of lower pressure)
Describe process of inhalation when at rest
- Diaphragm contraction most responsible for creating pressure imbalance
- Diaphragm pulls downwards
- External intercostal muscles contract
- Rib cage moves upwards and outwards.
- Thoracic cavity increases volume and decreases pressure, allowing oxygen rich air from the atmosphere (high pressure) to flow into the lungs (lower pressure)
Describe process of exhalation when at rest
- No energy required
- Diaphragm relaxes
- External intercostal muscles relax
Rib cage pulled inwards and downwards - Volume reduced and pressure increases to higher than atmosphere’s allowing air to flow back out again
What is Breathing Frequency & Acronym?
BR = Number of breaths per minute
What is Minute Ventilation & Acronym?
VE = Tidal Volume x Breathing Frequency
Product size of each breath
What is VE at rest? What can it increase to with heavy exercise?
VE = 6 L/min at rest
Can increase to +100 L/min with heavy exercise
What must body compensate for in any sort of exercise? What is done to compensate?
- In any sort of exercise, body must compensate for increased oxygen demand
- Various sensors within body will tell central controller in brain to increase VE (frequency of breaths & depth of breathing)
What is the change in Lung Volumes with Acute Exercise?
- VE of an individual will increase with an increased demand for oxygen during exercise, due to an increase in breathing frequency and depth of breathing
- Increase in TV comes at expense of certain volumes within lungs, such as ERV & IRV
Describe how IRV is affected during exercise
- Need to increase TV to get more air to increase oxygenation of blood
- “Space” is needed in lungs to accommodate extra volume of inhaled air
- Extra space comes from out of the IRV
- IRV acts as reservoir of extra lung volume so we can be inflated with air as we need it (more O2 inhalation & CO2 exhalation during exercise)
- Decrease in IRV when exercising due to TV increase taking over this “space” in lungs
- Eventually IRV can be used up, coinciding with physical size/stretch of lungs. This limit is rarely approached by healthy individuals during exercise
What factors affect lung capacity?
Age: younger people have smaller capacities
Gender: females have smaller capacity than males (20-25% lower)
Body Mass: larger mass = larger capacity
Muscle Mass: larger mass = larger capacity
Aerobic Fitness: breathing large breaths on a frequent basis = capacity
Explain mechanics of Ventilation in human lungs (Inspiration)
- Diaphragm: Contracts & Flattens
- Intercostal Muscles: External intercostal muscles contract and internal intercostal muscles relax
- Rib Cage: Upwards & Outwards
- Accessory Muscles: trapezius, sternocleidomastoid, scalene, pectoralis minor, and back muscles. These muscles help to pull the ribcage upwards during inhalation
- Thoracic Volume: Thoracic cavity volume increases, lungs increase in capacity
- Thoracic Pressure: Thoracic cavity pressure decreases
- Air Movement: Air from atmosphere (high pressure) rushes into lungs (low pressure)
- Depth / Frequency: Increase of depth of inhalation and frequency of inhalation
Explain mechanics of Ventilation in human lungs (Expiration)
- Diaphragm: Relaxes and moves upwards
- Intercostal Muscles: External intercostal muscles relax and internal intercostal muscles contract
- Rib Cage: Downwards and Inwards
- Thoracic Volume: Thoracic cavity volume decreases, lungs decrease in capacity
- Thoracic Pressure: Thoracic cavity pressure Increases
- Air Movement: Air moves out the lungs from high pressure to low pressure
- Depth / Frequency: Increase depth of exhalation and frequency of exhalation
What accessory muscles are involved in ventilation and what is their purpose?
Trapezius, sternocleidomastoid, scalene, pectoralis minor, and back muscles.
These muscles help to pull the ribcage upwards during inhalation
What happens with the diaphragm during ventilation?
Inhalation: contracts & flattens
Exhalation: relaxes and moves upwards
What with the intercostal muscles during ventilation?
Inhalation: External intercostal muscles contract and internal intercostal muscles relax
Exhalation: External intercostal muscles relax and internal intercostal muscles contract
What happens with the rib cage during ventilation?
Inhalation: upwards & outwards
Exhalation: downwards & inwards
What happens with the Thoracic Volume during ventilation?
Inhalation: Thoracic cavity volume increases, lungs increase in capacity
Exhalation: Thoracic cavity volume decreases, lungs decrease in capacity
What happens with thoracic pressure during ventilation?
Inhalation: Thoracic cavity pressure decreases
Exhalation: Thoracic cavity pressure Increases
What happens with air movement during ventilation?
Inhalation: Air from atmosphere (high pressure) rushes into lungs (low pressure)
Exhalation: Air moves out the lungs (now higher pressure)
How is breathing depth/frequency affected during ventilation?
Inhalation: Increase of depth of inhalation and frequency of inhalation
Exhalation: Increase depth of exhalation and frequency of exhalation
What happens to blood during exercise?
When blood has more CO2 it becomes more acidic
When doing exercise, increase of muscle contraction (cell respiration) leads to higher CO2 levels. Then, CO2 diffuses into blood.
Why does blood become more acidic?
Increase in CO2 leads to increase of H+ ions therefore increase in blood PH
CO2 + H2O → H2CO3 → HCO3 + H+
What does medulla oblongata do?
Increases breathing frequency & depth of breathing to meet increased oxygen requirement & maintain blood chemistry between narrow limits.
Describe chemical control of ventilation during exercise?
- Ventilation regulated by blood acidity or lower blood PH
- Exercise increases muscle contraction (cell respiration) which leads to higher levels of CO2 making blood more acidic (lowering the PH)
- Blood acidity levels detected by chemoreceptors, which send information to respiratory center located in medulla oblongata
- Increase of blood acidity and information provided by proprioceptors increases depth & rate of ventilation
- Proprioceptors = receptors located in muscles, tendons and joints that detect changes in movement and provide information to brain about body position & movement
- Baroreceptors = Special sensors located in carotid sinus and aorta which provide brain with information about blood pressure
What causes higher levels of CO2? What does it lead to?
Increase of muscle contraction (cell respiration) which leads to higher levels of CO2 making blood more acidic (lowering the PH)
What do chemoreceptors do?
It detects blood acidity levels, and sends information to respiratory center located in medulla oblongata
What are proprioceptors?
Receptors located in muscles, tendons and joints that detect changes in movement and provide information to brain about body position & movement
What are baroceptors?
Special sensors located in carotid sinus and aorta which provide brain with information about blood pressure
Describe nervous control of ventilation during exercise?
- Breathing manipulated by autonomic nervous system to increase rate & depth of breathing when exercising
- Respiratory center found in brain stem / medulla oblongata & pons in the brain
- Chemoreceptors relay information to respiratory center regarding lower PH (lower O2 levels / higher CO2 levels). In carotid artery & aorta
- Proprioceptors relay information to respiratory center regarding action of muscles / spindles / joint receptors
- Respiratory center increases stimulation (via phrenic nerve & intercostal nerves) to the inspiratory muscles (external intercostals and diaphragm)
- During exercise, inspiratory muscles are stimulated to contract more forcefully
- Respiratory center stimulates additional accessory muscles (sternocleidomastoid, pectoralis minor and scalenes) to increase depth and rate of breathing
- Stretch receptors / mechanoreceptors in the lungs in lungs relay information to respiratory center to prevent over inflation in lungs
- In response to stretch receptors, respiratory centre shortens duration of inspiration
- This is called Hering-Bruer reflex
respiratory center stimulates expiratory muscles (internal intercostals / obliques / rectus abdominis) to contract. - Expiration moves from passive to active control during exercise
Where is the respiratory center found?
In brain stem / medulla oblongata & pons in the brain
What do chemoreceptors do? Where are they found?
Chemoreceptors relay information to respiratory center regarding lower PH (lower O2 levels / higher CO2 levels)
Found in carotid artery & aorta
What do proprioceptors do?
Relay information to respiratory center regarding action of muscles / spindles / joint receptors
What does respiratory center do? Vía what?
Increases stimulation (via phrenic nerve & intercostal nerves) to the inspiratory muscles (external intercostals and diaphragm)
What happens to inspiratory muscles during exercise?
stimulated to contract more forcefully
Respiratory center stimulates additional _______ to do what?
Additional accessory muscles (sternocleidomastoid, pectoralis minor and scalenes) to increase depth and rate of breathing
What do stretch receptors / mechanoreceptors do?
Relay information to respiratory center to prevent over inflation in lungs
What is Hering-Bruer reflex?
When I’m response to stretch receptors, respiratory centre shortens duration of inspiration
What happens with expiratory muscles (nervous control)?
Respiratory center stimulates them (internal intercostals / obliques / rectus abdominis) to contract
What happens with expiration during exercise?
Moves from passive to active control during exercise
Describe how breathing is controlled during exercise
Increase in CO2 = decrease in PH
Decrease in PH detected by chemoreceptors
Movement detected by proprioceptors
This stimulates ANS to increase depth of breathing
Baroreceptors inform ANS to increase rate of breathing
Increase in rate of breathing causes lungs to stretch further
What do red blood cells carry and what percentage of the blood do they represent?
Red blood cells carry O2 & CO2
Red blood cells represent 45% of the blood
What is partial pressure?
Percentage concentration x total pressure of gas mixture
What is hemoglobin? What is it made up of?
Protein located in red blood cells
Made of four polypeptides associated with four prosthetic heme groups which contain iron
What is irons function?
It is where oxygen binds
What can each hemoglobin carry?
Each hemoglobin can carry four oxygen molecules from lungs to body
They can also carry CO2 as carbaminohemoglobin back to the lungs for diffusion and expiration
What is Role of Hemoglobin in Oxygen Transportation?
- Oxygen at lungs collected mostly by red blood cells (98.5%)
Where they combine with hemoglobin to form oxyhemoglobin (O2 saturated hemoglobin) - The rest (1.5%) diffuses into blood plasma
Oxygen dissolved in plasma determines movement of oxygen from cells into blood (pressure gradient) - Plasma PO2 determines loading of hemoglobin at lungs and unloading of oxygen at cells
- When there is low PO2, hemoglobin gives up its oxygen to the plasma (now becomes part of blood)
- This increases PO2 of the blood in relation to surrounding cells. Oxygen moves from blood to the cells
What determines movement of oxygen?
Difference of partial pressure
What is blood PO2 and Tissue PO2 when oxygenated blood reaches tissues capillary?
Blood: 95 PCO2
Tissue: 20 PCO2
What is PCO2 in tissues and blood when oxygenated blood reaches tissues capillary?
Blood: 40 PCO2
Tissues: 46 PCO2
What will veins partial pressure of CO2 and O2 be compared to the tissues? Why?
It will be the same:
Blood PO2 = 40 & PCO2 = 45
Tissue PO2 = 40 & PCO2 = 45
What are features of the alveoli?
- Tiny, circular air sacs which increase surface area of lungs
- Have moist, thin walls (just one cell thick), which assists gas exchange
- Surrounded by huge capillary network (little veins specialized in gas exchange)
- Distance between gas inside alveoli and capillaries lumen is about 0.5 um
- Small distance facilitates diffusion which increases rate of gas exchange
What is Fick’s Law? What is it used for?
Used to measure rate of diffusion
Rate of diffusion = area of diffusion surface x difference in concentration / thickness of surface over which diffusion takes place
Explain Fick’s Law in ventilation
- The larger the surface area and difference in concentration, and thinner the surface, the quicker the rate of diffusion
- Lungs surface area very large due to alveoli
- Difference in concentration maintained by breathing & blood flow
- Walls of alveoli one cell thick
- Therefore, diffusion rate is high
