carotid body Flashcards
carotid body is called the what, and why?
peripheral chemosensor: in the periphery, and senses oxygen levels in the blood
how many carotid bodies? location? nerve?
2: in the bifurcation of the common carotid artery. carotid sinus nerve innervating it.
carotid body: sensor of what 4 things
hypoxia (low arterial blood O2). hypercapnia (high arterial blood CO2). acidosis. hypoglycemia.
structure of carotid body: cell types
clusters of type I glomus cells, which are enveloped by type II glial like sustentacular cells
glomus cells: contain what? do what to what so info goes where?
secretory granules. glomus cells are what sense oxygen, and in response release transmitters and stimulate carotid sinus nerve and info is relayed to cardiorespiratory centre in brain stem.
secretory in glomus cells: what 4 NTs
ATP, DA, ACh, histamine
physiological role of CB; 2
adaptation to high altitudes. ensure sufficient oxygenated blood supply to tissues via fast respiratory and cardiocirculatory adjustments
CB: acute hypoxia what adjustments do you get
increase rate of respiration and blood pressure (increase in sympathetic drive)
pathophysiology of CB linked to what
sleep apnea related cardiovascular diseases
sleep apnea; what? two types?
brief, repeitive cessations of breathing during sleep. obstructive and central.
how does sleep apnea lead to cardiovascular problems
episodes of hypoxia during SA = low arterial O2 = stimulation/sensitization of CB = increase in sympathetic tone = congestive heart failure, hypertension, atherosclerosis
animals: intermittent hypoxia cuases what?
increases hypoxic sensory response of the CB: you develop and increase in sympathetic tone and hypertension
sleep apnea: denervation of carotid body?
blocks development of hypertension of animals subjected to intermittent hypoxia: so proves it’s the CB that causes hypertension
sleep apnea and CHF and atherosclerosis
patients with CHF have enhanced activity of peripheral chemoreflex and sympathetic hyperactivities. intermittent hypoxia elevates plasma cholesterol, induces atherosclerosis
what cell is the oxygen sensor
glomus cell
hypoxia triggers what in what cell
glomus cell: hypoxia triggers firing of APs, and rise in intracellular calcium in single glomus cell
experiment: single glomus cell recording membrane potential and calcium rise
normoxia: spontaneous APs and corresponding increases in [Ca]i. hypoxia: increase in Vm and AP firing, increase in calcium. back to normoxia: drop to basal state of Vm, normal Ca levels
mechanism of oxygen sensing in CB
glomus cells sense hypoxia, respond with an increase in AP firing and calcium levels
hypoxia triggers what two things from glomus cell
calcium intracellular rise, and transmitter release (measuring via carbon fiber amperometry)
normoxia: what mmHg?
150 mmHg of oxygen is normal
which NT actually stimulates the CSN
ATP (an experiment measured DA, but can be a measure of ATP release since in the same granules)
