The sympathetic branch primarily controls vascular smooth muscle through the release of norepinephrine from sympathetic nerve endings, which binds to adrenergic receptors on the smooth muscle cells. This binding causes vasoconstriction, increasing vascular resistance and blood pressure. Additionally, sympathetic stimulation can also lead to the release of epinephrine from the adrenal medulla, further enhancing vasoconstriction. Overall, this regulation helps maintain blood flow and pressure during stress or physical activity.
Each arrector pili is composed of a bundle of smooth muscle fibres which attach to several follicles (a follicular unit), and is innervated by the sympathetic branch of the autonomic nervous system. The contraction of the muscle is therefore involuntary - stresses such as cold, fear etc. may stimulate the sympathetic nervous system and thus cause contraction, but the muscle is not under conscious control.
It varies: In the somatic system (skeletal muscle) and parasympathetic branch of the autonomous nervous system (smooth & cardiac muscle) it is usually acetylcholine. In the sympathetic branch of the autonomous nervous system (smooth & cardiac muscle) it is usually norepinephrine (also called noradrenaline). There are exceptions, but this is the general rule.
The involuntary muscles are primarily composed of smooth muscle and specialized striated muscle known as cardiac muscle. All skeletal muscle is under voluntary control. Hence, the involuntary muscles are under control of the autonomic nervous system, which can be further divided into the sympathetic and parasympathetic divisions. The sympathetic division is readying the body into action, hence the "fight or flight" response associated with it, and the parasympathetic division associated with "rest and digest". :)
Neurons of the sympathetic branch of the autonomic nervous system primarily release neurotransmitters at adrenergic effectors, which include smooth muscles, cardiac muscle, and glands. The main neurotransmitter released is norepinephrine, which binds to adrenergic receptors to mediate the "fight or flight" responses. In some cases, such as sweat glands, sympathetic neurons also release acetylcholine, acting on muscarinic receptors.
Smooth muscle is mostly in the afferent branch going from the arteries to the arterioles. The body controls where blood will flow by controlling the vessel diameter. An increase in sympathetic tone constricts smooth muscle, decreases blood vessel diameter, and limits blood flow.
Eosinophils play a role in modulating inflammatory responses, but they do not directly control the vascular effects of serotonin and histamine. Instead, these vasoactive substances primarily exert their effects through interactions with vascular smooth muscle cells and endothelial cells. Eosinophils can influence the overall inflammatory environment and may indirectly affect the actions of serotonin and histamine, but they are not the primary regulators of their vascular impacts.
Sympathetic nervous system activation will increase the frequency and force of cardiac myocyte contractility
Sympathetic stimulation of the eye will cause dilation of the pupil (mydriasis) and relaxation of the ciliary muscle for far vision.
No, sympathetic and parasympathetic nerves do not supply voluntary skeletal muscles. These nerves primarily innervate smooth muscle, cardiac muscle, and glands, helping to regulate involuntary functions in the body. Voluntary skeletal muscles are under the control of the somatic nervous system.
It can cause vascular smooth muscle contraction
The sympathetic and parasympathetic nervious system.
Muscle tissue