The Respiatory System Flashcards
What is ventilation?
-movement of air into and out of the lungs
What is respiration?
- exchange of gasses (O2 and CO2)
- happens at many tissue levels: tissue (internal-tissues consuming oxygen from blood which got oxygen from alveoli), between blood and tissue (internal), between blood and lungs (external)
- definition includes ventilation: can’t have tissue respiration without ventilation in alveoli
What is aerobic tissue respiration?
- refers to utilization of oxygen and CO2 production by metabolizing tissues
- create ATP using fuel and oxygen
- rates at which you consume oxygen VO2 (volume/time- bringing oxygen into body and tissues use it and convert to CO2)
- rates at which you produce CO2
- can collect this as volumes over time
- rate of oxygen consumption depends on fitness (how much skeletal muscle- they are chief tissues that consume oxygen when you are active and at rest because you have higher BMR)
What is the rate of CO2 production with carbohydrate, fat,
Carbohydrate:
1 O2+ CHO –> H2O + 1 CO2 (1:1)
Fats:
1 O2+ fat –> H2O + 0.7 CO2 (1:0.7)
Combined CHO and fats –> 1:0.85
What is anaerobic tissue respiration?
- refers to the production of ATP without the utilization of oxygen
- this still contributes to the production of CO2 (doesn’t matter if you consume oxygen or not, you still produce CO2 as a waste product)
- skeletal muscle will do max aerobic then it will do anaerobic
- generate lactic acid and less ATP
- lactic acid changes pH which causes pain
- whenever you produce an acid, the proton that dissociates can combine with carbonate ion and eventually dissociate into H2O and CO2
Is metabolism ever purely aerobic or purely anaerobic?
- no
- try to do aerobic at its maximum (depends on how much oxygen you can get to tissue- function of gas exchange and delivery through CV system)
- anaerobic process is invoked to augment aerobic processes when the supply of oxygen cannot meet the energy demands of the tissues
- eg. MI or intense exercise (using muscle enough that you need anaerobic respiration, muscles start burning because lactic acid is being produced and stimulates free nerve endings to cause pain)
What is Boyles law?
PV=constant
- increase volume, decrease pressure (allows atmospheric air into lungs)
- decrease volume, increase pressure
- differences in air pressure drives air in and out of the lungs (ventilation)
What drives air into the lungs during quiet inspiration?
- diaphragm moves downward 1-2 cm
- external intercostals pull ribs/sternum up and out
- increases thoracic capacity– inspiration of 0.5L (tidal volume)
- this increases the volume of the lungs which decreases pressure in airways
- air comes in
- inspiration of 0.5L (tidal volume- goes up and down as you are breathing)
What drives air inside the lungs during forced inspiration?
- diaphragm moves 8-10cm
- scalenes, sternocleidomastoid elevate sternum and upper ribs
- external intercostals elevate lower ribs
- increases anteroposterior diameter of thorax
- increases superior and inferior volume
- inspiration of 3.5L (inspiratory capacity)
Where does a stitch originate from?
-if you have been exercising, thoracic spinal nerve running through thoracic VAN is conveying the pain (ventral rami of mixed spinal nerve)
(above happens in dermatomal distribution)
-pain from the diaphragm presents on the side of the neck and between your shoulder blades as referred pain from the phrenic nerve which originates from C3,4,5 (lactic acid build up in the diaphragm)
Why is breathing hard during the third trimester/obesity?
- womb has expanded
- diaphragm is up high
- 8-10cm movementn doesn’t happen easily so third trimester pregnant people can’t be super active
- the diaphragm can’t move down very far because there is baby there
- anatomic issue
What occurs during forced expiration?
- abdominal wall musculature compresses viscera and forces abdomen upwards
- muscles that pull downwards/fix inferior ribs (rectus abdominis (attached to costal cartilages, quadratus lumborum)
- internal intercostals depress ribs- pulls them downwards
- hydrostatic force created by pleural fluid allows the lungs to move with the diaphragm and thoracic wall (parietal pleura moving with thoracic wall brings the visceral pleura with it because of the hydrostatic force)
How is lung volume measured?
- spirometry
- patient breathes through tube into inverted dome
- when you breathe out, dome starts to float and move up
- breathe in air under the dome
- attach it to a pen so you can take a record of a breathing pattern
- normal in an adult is 6L
What is tidal volume?
-0.5L that is moving in and out normally at rest using principal muscles of inhalation and relaxing to breathe out
What is inspiratory reserve volume?
- extra air that you can bring in if needed by stretching lungs out even more
- useful to blow out candles
What is minute ventilation?
- V/t e
- collected expired air in bag and measured the volume after minute to give minute ventilation
- rate that air moves in and out of mouth
- how many breaths you took x tidal volume
What is alveolar ventilation?
- V/t a
- rate that fresh air moves in and out of alveoli
- less than Ve due to dead space volume of lungs (Vd)
- Vd=150mL
- more important than minute ventilation
- always less than what you would measure at the mouth
What is elastance?
- impedence to ventilation
- measure of stiffness of the lungs
- related to the forces needed to blow up a balloon
- high elastance= stiff lung
- lung with low elastance are compliant (emphysema); little elastic property to the tissue so it is easy to move them
- lung with high elastance are stiff (fibrosis-collagenous scar tissue, low surfactant) *long balloon
compliance=1/elastance
What contributes to elastic properties of lung?
- elastic tissue between alveoli only contributes about 1/3 of elastic recoil of lung
- most of it comes from fluid lining the alveoli and association of water molecules there (surface tension of water)
- elastic tissues are highly compliant (low elastance)
- surface tension of water has low compliance because it stiffens lungs (high elastance)
- water lining alveoli decreases lung compliance
What effect does surfactant have on surface tension?
- phospholipid released by type 2 pneumocytes and reduces surface tension of water
- reduces effort needed to breathe
- produced continually after 27-28 weeks gestation
- in normal conditions, surface tension still contributes 2/3 of elastic properties (helps you breathe out but not in)
- released by type 2 pneumocyte to reduce surface tension of the water
What is resistance?
- impedance to ventilation
- related to pressure needed to generate air flow
- can be likened to ‘drag’ which opposes air flow
- diameter of tube contributes most to resistance
- lungs with high resistance are obstructed (asthma, COPD)
- radius is largest factor
- with someone who has an obstructed lung, require bigger differences in pressure to get the same volume of air
How does pleural pressure relate to ventilation?
- lungs must move with the thoracic cage
- pressure in pleural cavity that is less than atmospheric air outside (negative pressure)
- keeps lungs adhered to the chest wall
What is positive ventilation?
- lungs are inflated by increasing the pressure inside the alveoli
- similar to mechanical ventilation of a patient or providing mouth to mouth resuscitation
- can inflate lungs by blowing them up at mouth
What is normal ventilation?
- lungs are expanded by reducing the pressure surrounding the lungs to sub-atmospheric pressures
- pleural cavity pressure decreases which pulls on the outside of the lungs making them larger (like a syringe pulling on pleural cavity)
Describe the breathing cycle
Before inspiration: no breathing is taking place and all respiratory muscles are relaxed
- lung volume= functional residual capacity
- outward forces=inward forces, negative pleural pressure
- lung elastic recoil tends to make lungs empty (naturally want to collapse to be small), thoracic cage elastance tends to make the chest wall expand
- no air movement because intrapulmonary pressure=atmospheric pressure
Inspiration:
- recruit muscles
- muscle forces make chest wall expand
- pulls on pleural space making it more negative so lungs expand
- when lungs achieve bigger volume, pressure in airway goes down which allows atmosphere to move into lungs
- Pip becomes subatmospheric
outward forces>inward forces
End of inspiration:
- lung elastic recoil is increased due to increased volume of lungs
- outward and inward forces are equally matched resulting in even more negative pleural pressure as these forces pull on the pleural space
- at this time, Pip is zero (equal to atmosphere) and no air flow occurs
During expiration:
- passive recoil of lung to drive expiration
- outward forces<inward></inward>
<p>-lung elastic recoil is larger than outward thoracic resistance causing lung volume to decrease</p>
<p>-as lung volume decreases Pip increases causing expiration</p>
<p>-Ppl will become less negative and lung elastic recoil will decrease</p>
<p> </p>
</inward>
-intrapleural pressure is always negative
