m11 + 12 lecture - respiratory system Flashcards
what is the respiratory system responsible for?
- the exchange and maintenance of blood gases and pH
what are the steps in the exchange and maintenance of blood gases and pH?
1) ventilation- airflow through the lungs
2) respiration - at the aveoli/capillaries
3) transport of gases through blood
4) respiration at the capillaries/ tissue cells
- all help to establish cellular respiration/ATP
what are the mechanics of ventilation (necessary components)?
1) air pressure changes -
vent. increases = pressure decrease
vent. decrease = pressure increase
2) intrapleural pressure - enables ventilation
3) compliance - elasticity
4) surfactant - decrease water tension, allows the aveoli to collapse/expand easily
what are some factors affecting ventilation?
- airway resistance
- loss of lung compliance
- loss of airway surface tension
what two actions does ventilation require?
- inspiration
- expiration
what is inspiration?
- it is an active process - contracting muscles which lower the pressure in the lungs to allow air to flow inward to the aveoli
- expansion of the lungs by expanding the rib cage
what are the inspiratory muscles?
1) diaphragm
2) external intercostals
- when contraction occurs - intrapleural pressure is created
—-> a neg. pressure
—-> a suction - lungs stick to the ribs
what is expiration?
- passage of air out of the lungs
— this is a passive process unless there is airway resistance
what is expiration directly initiated by?
- elastic recoil
- forced expiration
what is elastic recoil?
- tendency of the ribcage and lungs to contract to equal atmospheric pressure
- muscle relaxation
what is forced expiration?
- only seen when there is an issue
—> done thru muscular contractions of the - rectus abdominus, obliques, + internal intercostals
—> overcomes airway resistance (blockages)
how does airway resistance affect breathing? (factors affecting ventilation)
- directly effected by the size of the passage way
- bronchioles are the greatest contributor of airway resistance
—> smooth muscle in the bronchioles – dilate, constrict to affect airflow (ex. asthma, bronchitis)
—> irritants (allergens)
what is the reason for loss of airway surface tension? (factors affecting ventilation)
- surfactant decreases surface tension and prevents the tissue from sticking shut
ex.) IRDS - Infant Respiratory Distress Syndrome is a serious breathing problem that occurs in premature babies whose lungs are not fully developed
what is the reason for loss of lung compliance? (factors affecting ventilation)
- the ability of the lung to stretch and recoil
- decreased by anything which would decrease the elasticity of the lungs
ex.)
1) scarring, disease - emphysema, COVID
2) blockage of the bronchioles such as fluid - pneumonia
3) decreased flexibility of the rib cage
what are the different types of breathing?
eupnea - normal breathing rhythm (12-20 breaths)
dyspnea - difficulty (labored) breathing
hypernea - rhythm during exercise
what must there be for gas exchange to occur?
- a pressure gradient
—> exchange is driven by simple diffusion (high to low concentrations)
what is dalton’s law?
- partial pressures of gas
- (ATM) air pressure is 760mmHg
—-> this pressure’s made from the combined pressure of each gas in the atmosphere (1. nitrogen, 2. oxygen, H2O, + CO2) - air pressure is a constant measurement, but the partial pressures will change within each environment
—> if one increases, the others must decrease to maintain air pressure
is the external air the same concentration than the air in our lungs and blood gases?
no, air is much more humid in the lungs to prevent dehydration and drying in the mucus membrane
- % of O2 = 13% = pressure of 104mmHg
- deoxygenated blood = PO2 = 40 mmHg
what is henry’s law?
- gas disassociation into a liquid
—> gas will pressurize into a liquid according to the pressure in the air that it is in contact with (depends of the gas solubility and temperature)
ex.) soda, diving - hyperbaric chamber - bendz
Hg overcomes oxygens insolubility
male = 13-18g/100mL
female = 12-16g/100mL
what two things are needed for external respiration?
ventilation - air flow through the alveoli
perfusion - blood flow in the pulmonary capillaries
- at rest, we use 9-16% of our lungs (bottom)
alveolar air
- decreased ventilation = increased CO2 in the usual alveoli as CO2 increases, BF decreases = vasoconstriction
how is gas exchange maintained?
by the reflex actions of the arterioles
- arterioles dilate or contrict due to the % of CO2 in the alveolar air + blood
—> as air flow increases, this causes the BF to increase
—> as the body’s needs change, the air flow through a region of the lungs will also change
what does an O2 sat count?
the percentage of Hb with O2 attached
- 100% saturation is 100% of the Hb with O2
what is the gas exchange amount in the alveoli? (O2 and CO2)
percentage of O2 in the lungs = 13.7% or 104mmHg
percentage of CO2 in the lungs = 5.2% or 40mmHg
- these are the pressures that drive the gas exchange in the alveoli