Physiology Flashcards
Most potent stimulant of respiration in normal people
Arterial PCO2 sensed by central chemoreceptors
Where are the central chemoreceptors located?
Near the medulla
What do the central chemoreceptors respond to?
[H]+ of the CSF
In what two situations would the hypoxic drive become important in driving respiration?
Patients with chronic CO2 retention
High altitudes
Which structures are mainly responsible for detecting
Peripheral chemoreceptors
Where are the peripheral chemoreceptors located? (2)
Arch of the aorta
Bifurcation of the common carotids
Other than O2, what do the peripheral chemoreceptors measure which contributes to respiratory rate?
H+
Adjust for acidosis caused by the addition of non-carbonic acid (e.g. in lactic acidosis, diabetic ketoacidosis)
Accessory muscles of inspiration (2)
Sternocleidomastoid
Scalenus
Muscles of active expiration (2)
Abdominals
Internal intercostals
Major muscles of inspiration (2)
Diaphragm
External intercostals
How does pneumothorax cause lung collapse?
Equalises the atmospheric, intrapleural and intra-alveolar pressures so lung cannot expand
Intrinsic control of cardiac stroke volume
Venous return to the heart determines the preload; the higher the preload, the greater the stroke volume (Frank-Starling law)
Heart failure definition
Impaired pumping ability of the heart such that the physiological needs of the body are not met; usually resulting from a structural or functional cardiac disorder
Commonest cause of heart failure
Ischaemic heart disease
The role of J-receptors
Respond to pulmonary oedema, inducing reflexive hyperventilation
