Target type: biologicalprocess
The regulation of the rate of heart contraction mediated by chemical signaling, hormonal, autocrine or paracrine. [GOC:dph, GOC:mtg_cardio, GOC:rl, GOC:tb]
The regulation of heart rate, a vital process for maintaining blood flow and oxygen delivery throughout the body, is intricately controlled by chemical signals, primarily through the autonomic nervous system. This system, operating outside of conscious control, exerts influence through two branches: the sympathetic and parasympathetic nervous systems.
The sympathetic nervous system, often associated with the "fight-or-flight" response, releases neurotransmitters like norepinephrine (noradrenaline) at the sinoatrial (SA) node, the heart's natural pacemaker. This neurotransmitter binds to beta-adrenergic receptors on the SA node cells, initiating a cascade of events that increases heart rate. The mechanism involves the activation of adenylyl cyclase, which catalyzes the production of cyclic AMP (cAMP). cAMP then activates protein kinase A (PKA), which phosphorylates several proteins within the SA node, leading to an increase in calcium permeability and ultimately a faster depolarization rate.
Conversely, the parasympathetic nervous system, associated with "rest and digest" functions, primarily utilizes acetylcholine as its neurotransmitter. Acetylcholine binds to muscarinic receptors on the SA node cells, triggering a different signaling pathway. This pathway involves the activation of G-protein coupled receptors, which ultimately leads to the opening of potassium channels and a decrease in calcium permeability. The result is a slower depolarization rate and a reduced heart rate.
Beyond the autonomic nervous system, other chemical signals can influence heart rate. For instance, hormones like epinephrine (adrenaline) released during stress, can mimic the effects of norepinephrine, further increasing heart rate. Additionally, certain medications, including beta-blockers, can block the action of norepinephrine and epinephrine, reducing heart rate.
The interplay of these chemical signals ensures that the heart can adapt to diverse physiological demands, maintaining appropriate blood flow and oxygen supply under various circumstances. This finely tuned system demonstrates the intricate complexity of the body's regulatory mechanisms.'
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| Protein | Definition | Taxonomy |
|---|---|---|
| Sterol regulatory element-binding protein 1 | A sterol regulatory element-binding protein 1 that is encoded in the genome of human. [PRO:CNA, UniProtKB:P36956] | Homo sapiens (human) |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| calcifediol | D3 vitamins; diol; hydroxycalciol | bone density conservation agent; human metabolite; metabolite; mouse metabolite; nutraceutical |