Dr. Ryan - Respiratory lectures 1-2

what is the point of the respiratory system?

to get oxygen into our body to ensure that cells can make energy, and then getting rid of the byproduct, carbon dioxide

where is o2 going?

to the body

where is CO2 going?

away from the body,

what are the 4 key steps of the respiratory system?

ventilation, external respiration, transportation of gases, and internal respiration

what is ventilation?

the process of moving air into alveoli

what is respiration?

gas exchange across membranes in the body

what do alveoli do?

gas exchange

what are the parts of respiration?

external respiration (air inside alveoli is external and cross membrane), gas transport, and internal respiration

what are parts of external respiration?

O2 from alveolus moves into the blood and then moves CO2 from blood into alveolus

what are the parts of internal respiraiton?

O2 from blood into cells and then CO2 from the cells into the blood

how do gases move in ventilation?

bulk flow

what is bulk flow?

anywhere where there is ventilation

how do gases move in external and internal respiration?

diffusion, across membranes

what is ventilation?

moving air into and out of the respiratory system, breathing

where does ventilation reach?

starts at nose and mouth then ends up in the smallest airways

what is Va or alveolar ventilation?

the volume of air that is entering or leaving the alveoli with each breath and must be available for gas exchange

what is external respiration?

exchange of gases at lung/blood interference, gases move between walls of alveoli and pulmonary vessels, across the respiratory membrane

what does external respiration require?

air in the alveolus, healthy alveolar membrane, and blood flow past the alveolus

what are our oxygen carrying cells?

rbcs

where is gas dissolved?

plasma

what is internal respiration?

gases move between blood and tissue cells

what is cellualr respiration"?

O2 is used to produce energy for cells and CO2 is a byproduct

what is the commonality between all the respirations?

movement of gases

what is the oronasal zone?

oral and nasal cavity, pharynx

what is the conducting zone?

trachea all the way to the alveoli, trachea, bronchi, non-respiratory bonchioles

what is the respiratory zone?

any part of airway that has the exchange of gases, alveoli, respiratory bronchioles, ducts and sacs

what is the function of the oronasal zone?

olfaction, humidift and warm air, thermoregulate, filter air, slow airflow

how much resistance does the oronasal zone have for air flow?

50-70%

what are functions fo the pharynx/larynx?

phonation (making noises) and protecting the airway

T/F: horses are obligate nose breathers

TRUE

how does horse breath?

soft palate ventral to epiglottis, epiglottis dorsal to soft palate, and the aretynoids is open

how do we protect airway during swallowing?

soft palate raises, arytenoids rotate down to open esophagus, epiglottis rotates up to cover airway

what are conducting zone functions?

filter air, further slow air

what does the mucociliary apparatus do?

filter air

what is Vd or dead space?

the volume of inspired air in the respiratory tract that is not involved in gas exchange

what is anatomic dead space?

parts of the airway that are not alveolar exchange membranes

what is alveolar deadspace?

alveoli that are ventilated (has air in it) but not perfused with pulmonary capillary blood flow

what are the parts of anatomic deadspace?

oronasal zone and conducting zone

what is the difference between normal alveolar space and alveolar dead space?

in dead space there is no blood flow and no gas exchange

T/F; alveolar dead space is large in area for a healthy animal

FALSE; in a healthy animal should be minimal

what is perfusion?

blood flow

what is physiological dead space?

anatomical dead space and alveolar dead space combined

why is dead space increased when a patient is intubated?

increases the space in which there is no gas exchange, apparatus dead space, the volume within the tube is added to the overall dead space

what does increasing dead space do?

makes the patient have to do more work to move the gas down into airways

what is tidal volume or Vt?

volume of gas entering or leaving the respiratory tract during one breath

when does tidal volume increase?

with exercise

what is a spontaneously breathing animal’s tidal volume?

approx. 10-15 mls per kg

how do you calculate tidal volume?

volume of dead space + alveolar ventilation

how do you measure tidal volume with a spirogram?

volume of one inhalation OR passive exhilation

what are the 4 primary lung volumes we are measure?

tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume

what are the four lung capacities?

total lung capacity, functional residual capacity, inspiratory capacity, vital capacity

what is functional residual capacity (FRC)?

the volume of air remaining in lungs after passive exhalation

what is the clinical relevance of FRC?

one factor that is affecting diffusion of anesthetic gases into a patient

T/F: even if you force all the air that you possibly can, there is still a little bit of air in the alveoli

TRUE

what is minute ventilation?

volume of air that enters the lungs per minute

how do you get minute ventilation?

volume of breath x breaths/min or tidal volume x respiratory rate

at rest, what force are the lungs generating?

deflation/collapse, pulling inward

at rest what forces are the thoracic wall generating?

inflation/expansion, pulls outward

what are the two forces that contribute to the inward pull generated by the lung?

elasticity and surface tension

what is the elasticity of the lungs?

elastin fibers tend to pull lungs inward, force that makes lungs want to return to original position

what is the force of surface tension in the lungs?

tends to pull lungs inward

what reduces the surface tension in lungs?

surfactant

what are elastin fibers?

surrounds lower airways, help maintain shape and are structurally supported by collagen

in what state are elastin fibers in when an alveolus is distended during lung expansion (breathing)

stretched

what way do elastin fibers pull the lungs?

inward

what causes the surface tension in our alveoli?

a very thin layer of fluid lining the alveoli

how does surface tension work?

forces work to pull each alveolus shut, or to collapse or deflate

what is surfactant?

disrupts and reduces surface tension, produced by type 2 alveolar cells, 85-90% lipids, keeps alveoli from collapsing entirely, reduces work of breathing

what is pulmonary outward force generated by?

the chest wall/thoracic wall

what is the elasticity of the chest wall?

ribcage and muscles tend to pull lungs outward

why don’t the lungs separate away from the body wall?

pleural fluid generates negative pressure in the intrapleural space

what is parietal pleura

thin lining on the inside of chest wall

what is visceral pleura

thin lining of the lung

how is pleural fluid generatied?

hydrostatic and osmotic pressures

what is the intra-pleural space?

a “potential” space, filled with tiny volume of pleural fluid and reduced fluid between lung and body wall

what is negative pressure?

in the intrapleural space, suction that pulls visceral and parietal pleura together

what happens when you take negative pressure away?

collapsed lung

T/F: inspiration is always active

TRUE

what are inspiratory muscles?

diaphragm, external intercostals, accessory muscles like the scaleneus, sternomastoid

what does it mean that inspiration is active?

select muscles are working together to overcome forces

what do the external intercostals do in contraction/inspiration?

elevates ribcage, increases the volume of the chest

what does the diaphragm do in contraction/inspiration?

moves itself towards abdomen

T/F: expiration can only be passive

FALSE; can be passive or active

what happens after inhalation?

relaxation of inspiratory muscles occurs

what are expiratory muscles involved in active expiration?

internal intercostals, abdominal muscles, diaphragm

are the same muscles engaged in passive and active expiration?

no, in passive the inspiratory muscles just relax, in active there are different muscles doing work

what do internal intercostals do?

actively contract to pull ribs down

what do abdominal muscles do?

actively contract to pull ribs down, compresses abdominal contents

what is a heave line?

hypertrophied muscle from chronic increase in expiratory effort in response to diseased lung

what is boyles law?

pressure and volume are inversely related

what is the equation for boyles law?

p1v1=p2v2

how does boyles law apply to the lungs?

inverse relationship between pressure and volume, the more volume in the lungs means the less pressure of gas in the lungs, and vice versa

what is a pressure gradient?

the change in pressure measured across a given distance

how does gas move in relation to a pressure gradient?

moves from high pressure areas to low pressure areas

what is bulk flow in relation to pressure gradients?

gas moves from high pressure areas to low pressure areas

what is gas movement at rest?

pressure outside equals pressure inside, no movement of air

where in the respiratory tract does gas move via bulk flow?

oronasal zone and conducting zone

what is gas movement in active inspiration?

volume in lung increases, therefore, pressure inside lung decreases, pressure in lungs is lower in relation to pressure outside lungs, gas moves into lungs down pressure gradient

what is gas movement in expiration?

volume in lung decreases, pressure in lung increases so gas moves out of lungs down pressure gradient

how does intrapleural pressure compare to atmospheric and pntrapulmonary pressure at rest?

slightly lower, this pressure is negative and creating suction