Questions Flashcards
Respiration is referred to as 2 processes…
internal and external respiration
How are the cardiovascular and skeletomuscular systems both critical to the physiology of external respiration?
- by itself, the respiratory system is a series of air-filled tubes and spaces
- the thoracic and abdominal muscles (and thoracic cage) produce movements for ventilation
- the pulmonary circuit brings blood to the lungs for oxygenation
What are the secondary functions of the respiratory system and explain their purpose. (there is 3)
- Protective Barrier:
-> Keeps foreign substances (microbes, viruses or pollutants) in the air from entering the body - Sensory:
-> Neurons in the nasal cavities detect volatile ‘odorants’ aka smells - Communication:
-> Airflow is manipulated to allow for the production of speech and other sounds
The respiratory system has an upper and lower track what are their functions?
Upper Tract Functions:
- air conditioning (and conduction)
- olfaction
- Sound articulation
Lower Tract Functions:
- air conduction
- phonation
- (external) preparation
The lower respiratory tract is divided into conducting and respiratory portions. Identify what is in each portion.
Conducting Portion:
- Larynx
- Trachea
- Bronchi (3 types)
-> 2 primary bronchi
-> 5 lobar bronchi
-> 19 segmental bronchi
- Bronchioles (3 types)
-> 10s of 1000s of terminal bronchioles
Respiratory Portion:
- pulmonary lobules (respiratory bronchioles and alveolar sacs)
By the terminal bronchioles, what does the respiratory epithelium no longer have? What happens?
mucous and ciliated cells
- mobile macrophages ( type of phagocytic WBC) take over the protective functions performed by mucus
what are respiratory surfaces covered with?
- are covered with an epithelium that is specialized for rapid gas exchange
Where does external respiration ONLY occur?
- alveoli
- the rest of the respiratory tract is simply pathways for air to flow within
where can gas exchange ONLY occur?
where the air is near the capillaries of the pulmonary circuit
What is the respiration challenge and solution?
Challenge:
respiration requires fresh air to reach the alveoli regularly… however, the respiratory tract is a passive structure which continues air but cannot propel it and there is only 1 way in and out of the tract
Solution:
the body has evolved a pump that creates pressure gradients to move air for pulmonary ventilation
During quiet breathing what muscles are active?
ONLY primary inspiratory muscles are active
Is exhalation passive or active?
passive
During quiet breathing what happens to the exhalation phases?
the exhalation phase simply involves the relaxation of inspiratory muscles and the elastic recoil of the thoracic cavity
What happens during active (or forced) breathing?
accessory inspiratory and expiratory muscles are recruited to amplify movements
How are skeletal muscles involved in respiration?
- the respiration movement depends on skeletal muscles, and this one somatic motor neurons
Where are the motor neurons’ innervation and other inspiratory and expiratory muscles found?
are found in the cervical and thoracic spinal cord
what does the respiratory cycle depend on?
on neural activity generated within the medulla
The rate and pattern of breathing movements are generated by?
activity in respiratory centres in the medulla
no medullary respiratory center activity = NO
NO BREATHING (DEAD)
What drives the breathing muscles?
respiratory center neurons make synapses on the spinal motor neurons that drive breathing muscles
What activates Metabolic respiratory reflexes?
are activated by chemoreceptors in elastic arteries and the medulla
In addition to affecting brainstem cardiovascular centres chemoreceptors also…and why?
stimulate medullary respiratory centres to increase respiratory relate and volume
When does recruiting accessory breathing muscle increase?
it increases the energy demands of respiratory movements, so these are usually only used when oxygen demand is high
How much effort does it take to inflate a lung?
- Resistance
-> how to detect
-> how does it affect the lungs
Resistance:
-> The person is unable to fully fill their lungs
-> Even at rest, the person has to do more work to achieve the same volume of air-inspired
-> detected in spirometry by reduced FVC (or TLC)
-> detect by examining a patient’s detect by examining a patient’s (forced) viral capacity (FVC)
-> is characterized by lower capacity for air across most measures of lung function
-> is the measurement of how much force is needed to make air flow through conducting pathways
-> The diameter of airway passages is a major determinant of the overall resistance (and bronchioles are the biggest contributors)
Volume Flowrate (mL/s) = F = (P1-P2)/R
Resistance to flow: R = (8nL)/pir^4
How much effort does it take to inflate a lung?
- Compliance
Compliance:
-> is a measurement of how much work it takes to expand/inflate the lungs at a given pressure
-> More force required for lung inflation = LOWER compliance
-> Compliance can relate to properties of lung tissue or to properties of the skeletomuscular elements (ex: joint) involved in producing the lung movements
Obstructive Lung disease
- 2 examples and explain both
- how to detect?
- are diseases of increased resistance caused by changes to conducting pathways
- the conducting pathways to the lung tissue are obstructed, which reduces the flow rate
- a patient must of more work to get air to and from the lungs in the asset
- detected by spirometry
- Asthma
- caused by airway inflammation and bronchoconstriction - Chronic bronchitis/ chronic obstructive pulmonary disease
- caused by inflammation leading to overproduction of mucus that clogs airways
Reduction in gas exchange surfaces =
- what else happens?
- why does the respiration rate increase?
an increase in respiration rate and increased dead space in the lungs
- co2 cannot be removed bc/ used air is trapped in the lungs due to the lack of elastic recoil
- to maintain blood PO2 and reduce PCO2 through chemoreceptor reflexes
The amount of dissolved gas in a solution is proportional or reversely proportional to the partial pressure of that gas in the air?
proportional
When does blood gas composition reach equilibrium and what happens?
- at resting state
- the blood-air barrier and systemic capillary walls is favourable for rapid diffusion
- by the time the blood reaches the venues, blood PO2 and PCO2 have each been able to equilibrate with surrounding tissue (alveolar or peripheral tissue)
Note: if the pressure gradient changes (ex: during exercise) or the anatomy is affected by pathology (ex: lower respiratory infection), this may no longer be the case
What can respiratory reflexes increase and aim?
- they can increase the rate of gas exchange at the alveoli
-> by refreshing the pressure gradient
-> by increasing the functional alveolar surface area - aim to enhance differences occurring at the alveoli
- will increase the exchange of air between the outside and the alveoli, refreshing the partial pressure gradient
When is the rate of diffusion is the greatest?
when the difference in partial pressure is greatest
What happens when you increase the tidal volume?
- will further inflate the alveoli
- increasing surface area for diffusion (and potentially slightly decreasing barrier thickness)
Gas must be transported via…?
blood to reach the tissues
When is O2 and CO2 not THAT soluble?
under physiological pressure
What carries oxygen around?
- haemoglobin (O2 bound to haemoglobin packed into RBCs)
- blood leaving pulmonary capillaries carries about 20mL of o2 per 100mL of whole blood
- less than 2% is dissolved in the plasma
What do haemoglobin contain
- 4 protein subunits
- 4 haem molecules
- 2 iron ions that each bind to O2
What happens when tissues are aerobically active (decrease PO2)?
- hemoglobin automatically offloads more O2
- during exercise, skeletal muscle metabolic rate increases substantially and O2 is used for aerobic ATP generation, dropping PO2 to 15-20 mmHg
- this change in the pressure gradient promotes extra offloading of oxygen by haemoglobin, meaning substantial extra oxygen can be delivered even without an increase in blood flow
What happens when tissue becomes acidic (decrease pH)?
- haemoglobin saturation curves shifts, favouring O2 offload to active tissues even at higher PO2
- during intense exercise, skeletal muscle creates extra CO2 and many create metabolic acids if metabolism becomes anaerobic
- this relationship is known as the Bohr Effect
What happens when tissue increases in temp?
- haemoglobin saturation curves shift, favouring o2 offload
- a byproduct of ATP production (especially mitochondrial respiration ) is increase heat
- higher temp. favours O2 offload, thus enhancing O2 delivery to active tissues
What manages CO2 transport?
- inside RBCs, CO2 can be bound to haemoglobin, or converted to carbonic acid
- about 7% of the CO2 produced by peripheral tissues is dissolved in plasma
- the rest is taken u by RBCs and processed for other transport mechanism
What happens to the rest of the CO2 that doesn’t bind to haemoglobin, or is converted to carbonic acid?
converted to H2CO3 by carbonic anhydrase, an enzyme which has high levels in RBCs (this reaction is also freely reversible)
How are H+ ions formed?
- by carbonic acid, dissociation can also be transported bound to haemoglobin
- H2CO3 is a weak acid (partially) dissociated in solution, creating HCO3- and H+ ions
- haemoglobin can bind the H+ ions, buffering the solution against changes in pH and favouring O2 offload (and this uptake) by haemoglobin
How does CO2 transport in 3 ways?
- in the bloodstream and removed from blood at the alveoli
- all 3 methods are easily reveres at the alveoli with a partial pressure gradient that favours CO2 movements into air
- Dissolved in solution
- Bound to haemoglobin
- Converted to carbonic acid and bicarbonate/ H+
