Physiology Flashcards
Where are central chemoreceptors located?
near the surface of the medulla
the proportion of the FVC expired in first second
FEV1/FVC ratio
The Bohr Effect causes a left shift in the oxygen-dissociation curve - true or false?
false it causes a right shift as it becomes easier for O2 to dissociate even at higher PO2s
Chronic adaptations to hypoxia (5)
- increase in RBC production
- Increase 2,3BPG produced within RBC - increases O2 offloading
- Increase no, of capillaries
- Increase no, of mitochondria - use O2 more efficiently
- Kidneys conserve acid - decrease arterial pH
At the lungs, O2 binding Hb ______ the ability of Hb to bind CO2 and H+
Weakens
Main muscle of inspiration at rest
Diaphragm
difference between myoglobin and haemoglobin?
haemoglobin has 4 haem groups, myoglobin has one
What can increased pulmonary compliance be a result of?
elastic recoil loss
Which effect does the Bohr Effect pair up with?
Haldane effect
Why is alveolar ventilation more important?
it represents the new air available for gas exchange with blood.
The graph for oxygen dissociation curve is….
sigmoidal
Average intra-pleural pressure during inspiration
754mmHg
What is the primary determinant of oxygen saturation of haemoglobin with O2?
PO2
Where can rhythm of breathing be modified?
The Pons
PAO2 = PiO2 - [PaCO2/0.8]
partial pressure of O2 in alveoli
If there is a decrease in blood pressure, the is a(n) _______ in ventilation
increase
Hypoxia at high altitudes is caused by…
a decreased partial pressure of inspired oxygen (PiO2)
Sectioning where causes ventilation to cease?
below the medulla
Surfactant is a mixture of proteins and carbohydrates - true or false?
False Surfactant is a mixture of proteins and lipids
Pneumothorax abolishes the ___________ and causes the lung to ______
transmural gradient, collapse
Compliance
A measure of effort that has to go into stretching or distending the lungs
Patients with Heart Failure will get SOB before….
pulmonary oedema occurs
Afferent discharge from irritated airwasy stimulates what reaction from the medulla…(4)
- short intake of breath
- closure of larynx
- contraction of abdominal muscles
- opening of larynx and expulsion of air at high speed
If the partial pressure in a gas phase is increased, the concentration of the gas in the liquid phase would decrease proportionally - true or false?
false According to Henry’s Law it would increase proportionally
PiO2
partial pressure of inspired air
Amount of O2 dissolved in the blood at rest?
3ml/L
What types of pneumothorax can occur?
traumatic (wound to chest wall) spontaneous (lung side)
Sympathetic stimulation causes ________ and ________ resistance
bronchodilation and decreased
H+ dissociates from CO3- to join
Hb –> HbH
The ventral respiratory group neurons…
a. are activated during normal breathing
b. are activated during hyperventilation
c. are activated during apnoea
b. are activated during hyperventilation
Residual volume ________ when the elastic recoil of the lungs is lost as it becomes difficult to get the air out i.e. in ________
increases, emphysema
What are the accessory muscles of inspiration?
sternocleidomastoid scalenus
Rhythm for inspiration followed by expiration is generated by the _______
medulla oblongata
What does the Haldane effect work in tandem with?
The Bohr Effect
Ventilation
the rate at which gas is passing through the lungs
Increased _________ ___ as a result of increased ventilation causes pulmonary _______ which increases blood flow to match a larger airflow
alveolar O2, vasodilation
Cells that produce pulmonary surfactant
Type II alveoli
Forces keeping the alveoli open
Transmural pressure gradient Pulmonary surfactant Alveolar interdependence
Why are diseases airways not able to cope with dynamic airway compression?
the driving pressure is lost over the obstructed segment. This causes a fall in airway pressure downstream resulting in airway compression by the rising pleural pressure.
Why is alveolar ventilation less than pulmonary ventilation?
because of the anatomical dead space
How can respiratory distress syndrome of the New Born be prevented?
if prematurity is anticipated - provide mother with steroids to try and mature baby’s lungs
The hypoxic drive of respiration is completely through central chemoreceptors - true or false?
false
it is entirely through peripheral chemoreceptors
when are pulmonary stretch receptors likely to be activated?
during active inspiration where tidal volumes are >1L
A local tissue increase in O2 will cause systemic arterioles to ….
constrict - this avoids too much oxygen being offloaded where it is no longer needed
O2 consumption of our cells at rest
250ml/min
How does binding of one O2 molecule affect haemoglobin?
increases its affinity for oxygen in a co-operative manner
Which particular blood protein forms a carbamino compound?
globulin
Oxygen content of arterial blood can be calculated as…
CaO2 = 1.34 x Hb x SaO2
Conditions where the Bohr Effect might come into play?
- increased PCO2
- increased H+
- increased temperature
- increased 2,3-biphosphoglycerate
Why does HbF have a higher affinity for O2 than HbA?
to allow foetus to hijack O2 from mother
What is Respiratory Distress Syndrome of the New Born?
where newborn lungs are unable to produce the pulmonary surfactant to reduce the alveolar surface tension and thus have to make strenuous inspiratory efforts
What might a large difference between alveolar and arterial O2 partial pressure indicate?
issues with gas exchange or a right to left cardiac shunt
Normal CI
2.4-.42L/min/m2
What allows the lungs to relax and recoil?
elastic connective tissue alveolar surface tension
What adaptations do the lungs have to promote gas exchange?
large surface area promoted further by extensive alveoli and bronchial trees Extensive pulmonary capillary network
Average intra-alveolar pressure at rest
760mmHg
Joint receptors in exercise cause…
an increase in ventilation
H+ drive of respiration is driven by the _______ chemoreceptors
peripheral
Factors affecting rate of gas exchange (4)
- partial pressure gradient of O2 and CO2 - Diffusion coefficient for O2 and CO2 - Surface area of alveolar membrane - Thickness of alveolar membrane
Pre-Botzinger complex
a network of neurons which controls rhythms
What is internal respiration?
the intracellular mechanisms that consume oxygen and produces CO2
apneusis
inspiration prolonged with brief expiration
Residual Volume
minimum volumes of air remaining in the lungs even after a maximal expiration 1200ml
Dorsal respiratory group neurons excites which muscles?
Inspiratory muscles
Diaphragm
External Intercostals
Sectioning above the medulla
a. retains fairly normal ventilation
b. causes ventilation ceases
c. causes an abnormal breathing pattern
a - it retains fairly normal ventilation
the rate at which blood is passing through the lungs
Perfusion
Neurons from the apneustic centre excite…
the inspiratory area of the medulla and prolong inspiration
What is ventilation?
the mechanical process of moving air between the atmosphere and alveolar sacs
What is the Haldane Effect?
where reduced Hb can bind more CO2 than HbO2 removing the O2 from Hb increases its ability to bind CO2 and CO2 generated H+
pulmonary compliance is reduced by factors such as…(5)
pulmonary fibrosis pulmonary oedema lung collapse pneumonia absence of surfactant
Parasympathetic stimulation causes bronchodilation and and decreased resistance - true or false?
false PS stimulation causes bronchoconstriction and increased resistance
Stimulation of peripheral chemoreceptors by H+ causes (2)
- hyperventilation
- increased elimination of CO2
The less compliant the lungs are, the more work is required to produce a degree of inflation - true or false
true
Forces promoting alveolar collapse
Elasticity of stretched pulmonary connective tissue Alveolar surface tension
A measure of effort that has to go into stretching or distending the lungs
Compliance