Respi Mechanics Flashcards
What is the partial pressure of oxygen and carbon dioxide at rest
Po2 = 100mmhg
Pco2 = 40mmhg
Exchange rate of o2 and co2 at rest
250ml/min oxygen
200ml/min co2
Epithelia type of the upper respiratory tract
Pseudostratified Ciliated columnar
Ventilation rate at rest
6-7L/min
About 500ml per breath
Cardiac output at rest
Blood 5L/min 70bpm 70ml/beat
What happens during quiet breathing
Diaphragm moves down, flattens
External intercostal muscles contracts
Ribs are pulled up and out
Volume increase
Expiration is PASSIVE
What happens during strenuous breathing, both inspiration and expiration
Inspiration - additional inspiration accessory muscles active
Expiration - additional abdominal muscles and internal intercostals muscles contract to oppose relaxation of the external intercostals
Muscles of inspiration
External
Diaphragm
Sternocleidomastoid (plus other inspiratory accessory muscles)
Muscles of expiration
Abdominal muscles (external oblique, internal oblique, rectus abdominis, trans versus abdominis)
Internal Intercostals
Why intraplueral pressure always negative
The chest wall always wants to expand and the lungs always want to collapse
Intrapleural pressure is the space between the lungs and chest wall
Tidal volume def
The volume of air in each breath (about 500ml/breath)
Why is high intensity breathing less efficient?
Gas flow is turbulent, uses more muscles , accessory muscles fatigue easily
Functional residual capacity (FRC)
Volume of air in the lungs at the end of quiet breathing
Elastic recoil of lung =====outward recoil of chest wall
Vital capacity
Maximal volume of air that can be expired after maximal inspiration
What is inspiratory reserve volume
It is the additional amount of air that can be inspired following normal quiet inhalation
What is expiratory reserve volume
It is the additional amount of air that can be expelled following normal quiet exhalation
What is Pb
Barometric pressure
About 760 mmhg
Conducting airways vs respiratory airways
Conducting - upper respiratory tract, about 30%, anatomical dead space, do not participate in gas exchange
Respiratory - gas exchange, terminal bronchioles to alveoli
Structure of the alveoli
300-400 million sacs
Polygonal shape
250um diameter
Type 1 and type 2
HAS MACROPHAGES
Large SA
Short diffusion distance
What is the function of type 2 cells
Known as septal cells
Secrete surfactant
For surafcetension
Gives lungs ability to expand and prevents collapsing of lungs
2 methods of oxygen transport in the body
Dissolved in blood
Main one is bound to haemaglobin
AMOUNT OF O2 IN BLOOD IS PROPORTIONAL TO THE PARTIAL PRESSURE OF O2
What compound makes up the heme Group
Iron porphyrin Conpounds
Each contains iron in the reduced ferrous form
What is the respiratory exchanges ratio
Ratio of co2 expired to 02 uptake
What is a normal respiratory ratio
0.8
Ie 80co2 to 100 o2
How is co2 transported
7% dissolved in plasma
23% bound to haemaglobin (in rbc)
70% converted to bicarbonate (carbonic anhydrase in RBC converts co2 to bicarbonate before it is released at tissues)
How to adjust acidity in blood?
Ventilation to adjust pco2 or using kidneys to regulate bicarbonate concentaiotn
What does the FEV1 to FVC ratio represent
Percentage of the lung volume expired in 1 second
A normal ratio greater than 70%
Less than 70% = obstructive lung disease
Greater than 70% = restrictive lung disease
Because lung volume decreased