Carotid Body Intro Flashcards
Oxygen is an essential component for life on Earth
proving a fundamental element in the survival of aerobic organisms
A vital role of O2 lies in the importance of the atmospheric gas in cellular respiration
whereby O2 is utilised by the mitochondria of the cell to generate energy in the form of ATP
In normal oxygen environments
mitochondria consume 90% of oxygen available to achieve a net production of 34 ATP per glucose molecule through ox phos
When partial pressure of O2 drops e.g.
Sea level 160mmHg
Basecamp everest 88mmHg
When partial pressure drops….
insufficient ATP production can lead to bioenergetic crisis and altered cellular homeostasis
Hypoxia defined as
Oxygen demand exceeds supply
Discovery of the O2-dependent prolyl-hydroxylase regulated HIF pathway
elucidated our understanding of the adapted cellular response to chronic hypoxia
HIF-mediated transcriptional regulation of pathways such as
erythropoesis
glycolysis
angiogenesis
can take up to 12 hours
HIF-independent immediate action in response to acute hypoxia
carotid body
carotid body structure
sensory organ
located at bifurcation of carotid artery
cluster of specialised cells with ability to sense oxygen levels in blood
type I neuron like glomus cell
In response to drop in O2
k+ channels on membrane inhibited
cell depolarisation
VGCC open and calcium influx
exocytosis
dopamine release
signal to medullary centre
hyperventilatory response
Other physiological mechanisms involved in CB
tachycardia
peripheral vasodilation
pulmonary vasoconstriction
improve oxygen delivery to tissues
Function of CB is well established however
the precise mechanism by which change in o2 tension is translated to a decrease in K+ conductance on the glomus cell membrane is not understoof
Five theories of acute oxygen sensing (in order and ref)
HO-2 (Kemp, 2005)
H2S (Olsen, 2006)
AMPK (Evans and Peers, 2004)
ROS (Fernandes Agueres, 2015)
Olfr78 and lactate (Chang, 2015)
Other lactate theory (Torres-Torrelo, 2021)
