Physiology bits Flashcards
Which kind of alveolar cell secretes surfactant?
Type 2 alveolar cell
What physiological parameter is most closely related to afterload?
.
a) Mean arterial pressure (MAP)
b) arterial elastance
c) central venous pressure
d) end-diastolic volume
e) end-systolic volume
Mean arterial pressure (MAP)
Does prescribing beta blockers to patients with ischaemic heart disease increase or decrease coronary perfusion time?
Beta-blockers reduce heart rate –> increasing coronary perfusion time
Does an elevated expiratory reserve volume describe an obstructive or restrictive spirometry pattern?
Obstructive
To increase respiratory rate, chemoreceptors in the medulla respond to what stimuli?
increased CO2 in the cerebral spinal fluid (CSF)
Which nerve is involved in blood pressure information being transferred from baroreceptors to the nervous system?
via the 9th cranial nerve (glossopharyngeal nerve)
What stimulates central chemoreceptors?
H+ ions
In response to muscarinic blockade, what do the bronchi do?
Bronchodilation –> muscarinic receptors receive parasympathetic innervation, which leads to bronchoconstriction –> therefore blockade of these receptors results in bronchodilation
Mean arterial pressure (MAP) equations (two equations)
MAP (mean arterial pressure) = CO (cardiac output) x TPR (total peripheral resistance)
- MAP = arterial diastolic pressure + 1/3 pulse pressure
Where does the fastest conduction of an impulse occur in the cardiac conducting system?
Purkinje fibres –> specialised conduction fibres
In chronic hypercapnia, the central chemoreceptors become less sensitive to CSF pH changes caused by the high levels of CO2 –> what is responsible for respiratory drive in chronic hypercapnia?
Arterial oxygen levels –> chemoreceptors become reliant on the hypoxic drive instead
Central chemoreceptors are involved in regulating breathing.
Where are the central chemoreceptors located?
Ventral medulla
Where are capillaries with open pores in the endothelium found?
Hepatocytes
The Frank-Starling curve of the heart shows one variable being proportional to another variable under normal physiological circumstances.
What are the two variables that are linked via this curve?
Stroke volume and preload
At which point of the cardiac cycle does the highest volume of blood flow through the coronary arteries?
Ventricular diastole
Alveolar ventilation equation linking tidal volume and physiological dead space
High altitude –> what ABG is likely (pt is short of breath and lightheaded)
Respiratory alkalosis
What is expiratory reserve volume (ERV)?
ERV is the additional volume of air that can be forcefully exhaled below tidal volume
On the Frank-Starling curve, which variables are usually placed on the X-axis and Y-axis?
Describe the baroreflex mechanism of the cardiovascular system and how it detects and stops a drop in blood pressure
- A decrease in MAP reduces the stretch on the baroreceptors
- As a result, baroreceptors send less signals to the glossopharyngeal and vagus nerve to the medulla
- The sympathetic NS is therefore activated to increase the blood pressure
In emphysema, is lung compliance increased or decreased?
Increased –> due to loss of elastic tissue so less recoil and therefore lungs expand too much (hyperinflation) –> results in barrel (hyperexpanded) chest
Valsalva manoeuvre
The patient is asked to breathe out forcefully while closing their mouth and pinching their nose shut
Vital capacity is what?
- the maximal volume of gas that can be expelled from the lungs after a maximal inhalation or a full breath
. - Tidal volume + Inspiratory reserve volume + Expiratory reserve volume
Infective exacerbation of COPD –> what acid-base balance disorder is most likely? (shallow breaths)
Respiratory acidosis
