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
What is the difference between restrictive and obstructive lung diseases
Obstructive is blocked airways like emphysema COPD asthma oedema
Restrictive is like lower lung volume, pulmonary fibrosis neuromuscular diseases, religion distress syndrome
Lung volume is 80% or less of a healthy individual
What do chemoreceptors detect
Changes in pO2 pCO2 pH in blood
Where are the PERIPHERAL chemoreceptors located and which nerves relay signals to the NTS?
Nucleus tractus solitarius
Located in the aortic arch and carotid
Nerves are
Aortic arch - vagus
Carotid - carotid sinus and Glossopharyngeal
What do the peripheral and central chemoreceptors detect respectively
Peri - Po2 (hypoxia)
LITTLE PART IN CONTROL OF BREATHING , hyperventilation only activated below 60mmhg
Central - pco2 (hypercapnia)
MAJOR role in control of breathing. Very small changes in Pc02 has large effects on ventilation
What is a major control in breathing.
Central chemoreceptors, pco2
Describe the process of breathing
Which nerve are linked to peripheral chemoreceptors in the aortic arch
Vagus
Which nerve are linked to peripheral chemoreceptors in the carotid sinuses
Glossopharyngeal
Define ventilation and perfusion
Ventilation - process by which air moves in and out of the lungs
Perfusion - process by which deoxygenated blood passes through the lung and becomes oxygenated
Why is ventilation not uniformly distributed in the lung
Gravity pulls the lung down, the apex is more expanded than the base, pleural pressure more negative at apex
Compliance vs resistance
Compliance refers to stretch
Resistance refers to the narrowing or obstruction in the airways
Graph of compliance and resistance
Define physiological dead space
Total volume of gas in each breath that does not participate in has exchange so
Anatomical dead space + alveoli that are perfumed but not ventilated
Normal v/q ratio in healthy lungs
0.8-1.2
2 classifications for v/q ratio
Single alveolus
Entire lung
Single alveolus v/q ratio meaning
Alveolar ventilation divided by capillary flow
Lung v/q ratio meaning
Ventilation of all alveolar divided by cardiac output
Fev/fvc ratio in obstructive and restrictive lung diseases
Ratio less than 70% in obstructive because FEV decrease
Ratio more than 70% in restrictive because FVC (lung volume) less than 80% of normal
Vq ratio of physiological shunt
0
Where do most anatomical shunt occur
In heart , results in hypoxemia
Why doesn’t the pCO2 change in the anatomical shunt?
The Central chemoreceptors are very sensitive so they increase ventilation to reduce the pco2
COPD
obstructed airflow
Encompasses emphysema and chronic bronchitis
Emphysema
Lungs loose elasticity,
Cannot expand ,
Exhalation is difficult due to decreased elastic recoil
Chronic bronchitis
Excessive mucous production
Shortness of breath
Obstructive
Fibrosis
Scar tissue
Less able to expand, volume decreases
Restrictive
Asthma
Air flow reduced,
Obstructive
Large amount of mucous produced
De\istance between rbc and alveoli
1-2um
Roughly how many haemoglocbin do we have in our body
280milliom
2 ways in which oxygen is transported around our body
1 dissolved in blood but this makes up super small %
2 carried by haemaglobin
What equipment do we use to measure oxygen saturation in blood?
Pulse oximeters measures ratio of absorption of red and infrared light by oxyHb and deoxyHb
Total blood oxygen capacity per 1L
211ml/1L of blood
The NTS receives signals from which receptors
Baroreceptors +Chemoreceptors in the aortic arch and carotid sinus
Mechnoarecptors at the lungs
Is NTS dorsal or ventral
Dorsal
Are rhythm generating neurones dorsal or ventral
Ventral
Is cystic fibrosis obstructive or restrictive lung disease
Cystic fibrosis is a obstructive lung disease
Is COPD obstructive or restrictive
Obstructive
Is neuromuscular lung diseases obstructive or restrictive
Restrictive
Is emphysema and asthma obstructive or restrictive
Obstructive
Atelectasis
Obstruction of ventilation due to mucous Plugs, blood clot, airway oedema, foreign bodies, tumours in airways
What muscles are involved in active exhalation
Abdominal and internal intercostal
Does the oxyhemoglobin curve shift to the left or right if blood becomes more acidic
Shifts to the right
Which graph, resistance or compliance, is related to restrictive or obstructive diseases
Resistance graph is related to obstructive
Compliance graph is related to restructure diseases
