Respiratory Flashcards
In blood circulation what direction is the pressure gradient
gasses move down their pressure graident
describe the pulmonary circuit
O2 enters bloood CO2 leaves
Describe the sysemic circuit
O2 leaves blood CO2 enters
How does gas move throughout the respiratory system
diffusion
describe different anatomical and physiological properties to facilitate gas diffusion
Large surface area for gas exchange.
Large partial pressure gradients.
3) Gases with advantageous diffusion properties.
4) Specialised mechanisms for transporting O2 and CO2 between lungs and tissues.
what is partial pressure?
Sum of the partial pressures (mmHg) or tensions (torr) of a gas must be equal to total pressure
what are the two forms O2 is carried in the blood?
Dissolved
Bound to Heamaglobin
Is it a large or small amount of blood dissolved?
Only a small percentage of O2 in blood is in the dissolved form.
Amount of dissolved O2 in blood is proportional to its partial pressure
How is dissolved O2 measured clinically?
in arterial blood sample PaO2- piercing of artery (very invasive)
what is the amount of O2 dissolved in blood proportional too?
it’s partial pressure
Transport of O2 in dissolved form is not adequate for what?
Body’s requirement at rest.
How many heme groups are attached to the globin protein?
4 heam groups
What is the binding site for oxygen?
Each heme group contains
iron in the reduced ferrous
form (Fe+++), which is the
site of O2 binding.
how much oxygen does HB molecules in red blood cells
280 million Hb molecules
why does binding and dissociation of O2 with Hb occur in milliseconds?
because red blood cells in capillaries for one second only
Does the acidity of the blood affect the binding of Haemoglobin?
Yes so does temperature
Is O2 binding to Hb reversable?
Yes
What does oxygen saturation refer to?
to the amount of O2 bound to Hb relative to maximal amount that can bind.
When is Haemoglobin almost 100% saturated?
100 mmHg PO2
At what point does a drop in partial pressure have an effect?
<60 mmHg
How would you measure O2 saturation (SaO2)?
Pulse oximeter- measures ration of absorption and infrared waves
Healthy Individuals should have what percentage if oxygen saturation?
96-100% saturation
total oxygen capacity- 211 mlsO2/1L
How much more efficent is Haemoglobin at carrying oxygen around the blood?
hemoglobin 208 in 1L
dissolved 3 mls/ 1L
What is the respiratory exchange ratio?
Ratio of expired CO2 to O2 uptake
What are the 3 forms is CO2 carried in?
i)7% dissolved.
ii)23% bound to
haemoglobin (Hb).
iii) 70% converted to
bicarbonate.
In a bicarbonate reaction what effects does the concentration gradient have?
Speed and direction of the reaction
What has an effect in maintaining the acid-base balance in the body?
The CO2 to HCO3- pathway plays a critical role in regulation of H+ ions and in maintaining acid- base balance in body
What enzyme converts CO2 to HCO3
H2CO3
What organ/organs help to regulate bicarbonate concentration?
the kidneys
What shape is the O2 dissociation curve?
S-shaped Curve
Name some factors that affect Breathing
sleep, phonation, emotion, cardiovascular, temperature, exercise, mechanoreception, and chemoreception.
What modulates Breathing?
vocalisation, Physiological challenges, Emotion, reflexes, Volitional control- hold breath
Where does the brain receive neural breathing receptors from?
Chemoreceptors, mechanoreceptors
What do chemoreceptors feedback?
provide feedback on blood PO2, PCO2 and PH
What do mechanoreceptors provide feedback on?
the mechanical status of lungs, chest walls and airways
Where are the neural signals sent to?
respiratory muscles to produce rhythmic breathing, upper airway muscles
Why are reflexes important to breathing?
protects respiratory system and breathing
What are chemoreceptors?
Chemoreceptors are sensory receptors that detect chemical changes in the surrounding environment.
respiratory- changes in PO2, PCO2 and pH in blood.
What do peripheral chemoreceptors respond to?
Decrease in PO2- hypoxia
Where are peripheral chemoreceptors located?
in periphery- outside CNS
Describe Peripheral chemoreceptors
small, highly vascularised bodies
What is the ventilation response to Hypoxia
Below 60 mmHg there is a progressive hyperventilation.
Hypoxic response originates in carotid and aortic bodies
Where are central Chemoreceptors located?
brainstem
When would central chemoreceptors be stimulated?
when PCO2 is increased (hypercapnia) or pH decreased.
What is the ventilation response to hypercapnia?
Very small changes in PCO2 have large effects on ventilation (unlike O2). Hypercapnic response originates in central chemoreceptors in brainstem. Plays major role in moment to moment control of breathing
What are mechanoreceptors?
Mechanoreceptors are sensory receptors that detect changes in pressure, movement and touch. In respiratory system mechanoreceptors detect movement of lung and chest wall.
What activates mechanoreceptors?
Inflation of the lungs
What happens when mechanoreceptors detect inflation of the lungs?
Neural signals sent via vagus nerve to NTS in brainstem. Ventilation adjusted accordingly.
When the NTS receives info from mechanoreceptors and chemoreceptors where is the information processed?
in brainstem by respiratory neurons
what do the cluster of respiratory neurons generate?
the rhythm of breathing which is sent to respiratory muscle
What nerve innovates diaphragm
Phrenic nerve- exits spinal chord at level 3-5
why is there a large portion of the motor cortex dedicated to the hand
refine motor movements
What is ventilation?
process by which air moves in and out the lungs
is ventilation in the lungs happen uniformly?
no due to gravity
is the plural pressure more negative at apex or base
at apex
what is meant by compliance of the lung?
refers to how much effort is required to stretch the lungs and chest wall
What is decreased compliance a potential symptom of?
scarring of the lung, lung filled w fluid, deficiency in surfactant production, destruction of elatstic fibres- emphysema
What is meant by resistance of the lung?
refers to narrowing or obstruction of airway which may reduce airflow
Increased resistance is seen in what conditios?
asthma, COPD
Anatomical dead space?
volume of gas during which each breath fills the conducting airways
Physiological dead space?
total volume of gas in each breath that does not participate in gas exchange e.g. alveoli that are perfused but not ventilated
What are the lungs 2 blood supplies?
Bronchial cirulation and pulmonary circulation
is the pulmonary circulation a high or low pressure system?
low pressure also low resistance
What does the V/Q ratio refer to?
ratio of ventilation to blood flow
What can the V/Q ratio be defined by?
for single alveolus, a group of alveoli or the entire lung
What is a healthy aveolar ventilation
4-6 L/min
In a perfect model what would the V/Q equal?
V/Q=1
What is hypoxia?
when oxygen is insufiencent PO2>60
physiological shunt?
When is V-Q mismatching most frequent
due to arterial hypoxia in patients
When is V-Q mismatching most frequent
due to arterial hypoxia in patients
What is COPD?
a condition in which airflow is obstructed, encompasses emphysema and chronic bronchitis, long term smoking is a cause
What is COPD?
a condition in which airflow is obstructed, encompasses emphysema and chronic bronchitis, long term smoking is a cause
What is COPD?
a condition in which airflow is obstructed, encompasses emphysema and chronic bronchitis, long term smoking is a cause
Symptoms of COPD?
tight cough, inflammation of lungs
What is emphysema?
structures in alveoli over inflated, lungs loose elasticity cannot fully expand and contract, patients inhale but exhalation is difficult due to decreased recoil
What is chronic bronchitis?
inflammation of bronchi causing mucus production and excessive swelling, prone to infections
what is pulmonary fibrosis?
a type of interstitial lung disease, scarring and thickening of lung, decreased elasticity and gas exchange- usually die within 4 years.
