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Vasoconstriction is the narrowing of the
blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an organ system that permits blood to circulate and transport nutrients (such as amino ...
s resulting from contraction of the muscular wall of the vessels, in particular the large
arteries An artery (plural arteries) () is a blood vessel that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pulmonary arteries, pulmonary ...
and small
arterioles An arteriole is a small-diameter blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an organ system that permits blood to c ...
. The process is the opposite of
vasodilation Vasodilation is the widening of blood vessel The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. ...

vasodilation
, the widening of blood vessels. The process is particularly important in controlling
hemorrhage Bleeding, also known as a hemorrhage, haemorrhage, or simply blood loss, is blood Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrient A nutrient is a substance used by an organism to survi ...
and reducing acute blood loss. When blood vessels constrict, the flow of blood is restricted or decreased, thus retaining body heat or increasing
vascular resistance Vascular resistance is the resistance that must be overcome to push blood through the circulatory system and create fluid dynamics, flow.The resistance offered by the systemic circulation is known as the systemic vascular resistance (SVR) or may so ...
. This makes the
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biolo ...

skin
turn paler because less blood reaches the surface, reducing the radiation of heat. On a larger level, vasoconstriction is one mechanism by which the body regulates and maintains
mean arterial pressure In medicine, the mean arterial pressure (MAP) is an average blood pressure in an individual during a single cardiac cycle. Calculation The Systemic Vascular Resistance (SVR), denoted R is represented mathematically by the formula :R = \Delta P/ ...

mean arterial pressure
. Medications causing vasoconstriction, also known as vasoconstrictors, are one type of medicine used to raise blood pressure. Generalized vasoconstriction usually results in an increase in systemic blood pressure, but it may also occur in specific tissues, causing a localized reduction in blood flow. The extent of vasoconstriction may be slight or severe depending on the substance or circumstance. Many vasoconstrictors also cause
pupil dilation Pupillary response is a physiological Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology Biology is the natural science that studies life and living organisms, includin ...
. Medications that cause vasoconstriction include:
antihistamines Antihistamines are pharmaceutical drug, drugs which treat allergic rhinitis and other allergies. Typically people take antihistamines as an inexpensive, Generic drug, generic, over-the-counter drug that can provide relief from nasal congestion, ...
, decongestants, and
stimulant Stimulants (also often referred to as psychostimulants or colloquially as uppers) is an overarching term that covers many drug Uncoated tablets, consisting of about 90% acetylsalicylic acid, along with a minor amount of inert fillers and b ...
s. Severe vasoconstriction may result in symptoms of
intermittent claudication Intermittent claudication, also known as vascular claudication, is a symptom Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower tempe ...
.


General mechanism

The mechanism that leads to vasoconstriction results from the increased concentration of
calcium Calcium is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elem ...

calcium
(Ca2+
ions An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are u ...

ions
) within vascular
smooth muscle cells Smooth muscle is an involuntary non-striated muscle Striated muscle tissue is a muscle tissue that features repeating functional units called sarcomeres. The presence of sarcomeres manifests as a series of bands visible along the muscle fibers, w ...
. However, the specific mechanisms for generating an increased intracellular concentration of calcium depends on the vasoconstrictor. Smooth muscle cells are capable of generating
action potentials In physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology Biology is the natural science that studies life and living organisms, including their anatomy, phy ...
, but this mechanism is rarely utilized for contraction in the vasculature.
Hormonal A hormone (from the Greek participle , "setting in motion") is any member of a class of signaling molecules in multicellular organisms, that are transported to distant organs to regulate physiology and / or behavior. Hormones are required for ...
or pharmacokinetic components are more physiologically relevant. Two common stimuli for eliciting smooth muscle contraction are circulating
epinephrine Adrenaline, also known as epinephrine, is a hormone A hormone (from the Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in ...

epinephrine
and activation of the
sympathetic nervous system The sympathetic nervous system (SNS) is one of two divisions of the autonomic nervous system, along with the parasympathetic nervous system. The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes co ...
(through release of
norepinephrine Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical , CH4; is among the simplest organic compounds. In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and ...

norepinephrine
) that directly innervates the muscle. These compounds interact with cell surface
adrenergic receptors (yellow) on its extracellular site. β2 stimulates cells to increase energy production and utilization. The membrane the receptor is bound to in cells is shown with a gray stripe.The adrenergic receptors or adrenoceptors are a class of G protein- ...
. Such stimuli result in a
signal transduction Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most commonly protein phosphorylation residue Protein phosphorylation is a reversible post-translational ...
cascade that leads to increased intracellular calcium from the
sarcoplasmic reticulum The sarcoplasmic reticulum (SR) is a membrane-bound structure found within muscle cells that is similar to the smooth endoplasmic reticulum in other Cell (biology), cells. The main function of the SR is to store calcium ions (Ca2+). Calcium ion le ...
through IP3-mediated calcium release, as well as enhanced calcium entry across the
sarcolemma The sarcolemma (''sarco'' (from ''sarx'') from Greek; flesh, and ''lemma'' from Greek; sheath) also called the myolemma, is the cell membrane cell membrane vs. Prokaryotes The cell membrane (also known as the plasma membrane (PM) or cytoplasm ...
through
calcium channelsA calcium channel is an ion channel s (typically four per channel), 2 - outer vestibule, 3 - selectivity filter, 4 - diameter of selectivity filter, 5 - phosphorylation site, 6 - cell membrane. Ion channels are pore-forming membrane proteins that a ...
. The rise in intracellular calcium complexes with
calmodulin Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells Eukaryotes () are organism In biology Biology is the na ...

calmodulin
, which in turn activates
myosin light-chain kinase Myosin light-chain kinase also known as MYLK or MLCK is a serine/threonine-specific protein kinase that phosphorylates a specific myosin light chain, namely, the regulatory light chain of myosin II. General Structural Features While there are ...
. This enzyme is responsible for
phosphorylating In chemistry, phosphorylation of a molecule is the attachment of a phosphoryl group. This process and its inverse, dephosphorylation, are critical for many cellular processes in biology. Protein phosphorylation is especially important for their fu ...

phosphorylating
the light chain of
myosin Myosins () are a superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilie ...

myosin
to stimulate cross-bridge cycling. Once elevated, the intracellular calcium concentration is returned to its normal concentration through a variety of protein pumps and calcium exchangers located on the plasma membrane and sarcoplasmic reticulum. This reduction in calcium removes the stimulus necessary for contraction, allowing for a return to baseline.


Causes

Factors that trigger vasoconstriction can be exogenous or endogenous in origin. Ambient temperature is an example of exogenous vasoconstriction. Cutaneous vasoconstriction will occur because of the body's exposure to the severe cold. Examples of endogenous factors include the
autonomic nervous system The autonomic nervous system (ANS), formerly the vegetative nervous system, is a division of the peripheral nervous system that supplies smooth muscle and glands, and thus influences the function of viscera, internal organs. The autonomic nervous ...

autonomic nervous system
, circulating hormones, and intrinsic mechanisms inherent to the vasculature itself (also referred to as the
myogenicThe myogenic mechanism is how artery, arteries and arterioles react to an increase or decrease of blood pressure to keep the blood flow constant within the blood vessel. Myogenic response refers to a contraction initiated by the myocyte itself instea ...
response).


Examples

Examples include
stimulants Stimulants (also often referred to as psychostimulants or colloquially as uppers) is an overarching term that covers many drug Uncoated tablets, consisting of about 90% acetylsalicylic acid, along with a minor amount of inert fillers and b ...

stimulants
,
amphetamine Amphetamine (contracted from alpha-methylphenethylamine) is a central nervous system The central nervous system (CNS) is the part of the nervous system In biology Biology is the natural science that studies life and living orga ...

amphetamine
s, and
antihistamine Antihistamines are drugs Uncoated tablets, consisting of about 90% acetylsalicylic acid, along with a minor amount of inert fillers and binders. Aspirin is a pharmaceutical drug often used to treat pain, fever, and inflammation. A drug i ...

antihistamine
s. Many are used in medicine to treat
hypotension Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the Systole, systolic blood pressure (the top number) and ...
and as topical decongestants. Vasoconstrictors are also used clinically to increase
blood pressure Blood pressure (BP) is the pressure Pressure (symbol: ''p'' or ''P'') is the force In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motio ...

blood pressure
or to reduce local blood flow. Vasoconstrictors mixed with local anesthetics are used to increase the duration of local anesthesia by constricting the blood vessels, thereby safely concentrating the anesthetic agent for an extended duration, as well as reducing
hemorrhage Bleeding, also known as a hemorrhage, haemorrhage, or simply blood loss, is blood Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrient A nutrient is a substance used by an organism to survi ...
. The
routes of administration Route or routes may refer to: * Route (gridiron football) Route or routes may refer to: * Route (gridiron football), a path run by a wide receiver * route (command), a program used to configure the routing table * Route, County Antrim, an area ...
vary. They may be both systemic and topical. For example,
pseudoephedrine Pseudoephedrine (PSE) is a sympathomimetic Sympathomimetic drugs (also known as adrenergic drugs and adrenergic amines) are stimulant compounds which mimic the effects of endogenous Endogenous substances and processes are those that originat ...

pseudoephedrine
is taken orally and
phenylephrine Phenylephrine is a medication primarily used as a decongestant, to dilate the pupil, to increase blood pressure Blood pressure (BP) is the pressure Pressure (symbol: ''p'' or ''P'') is the force In physics Physics (from ...

phenylephrine
is topically applied to the nasal passages or eyes. Examples include:


Endogenous

Vasoconstriction is a procedure of the body that averts
orthostatic hypotension Orthostatic hypotension, also known as postural hypotension, is a medical condition wherein a person's blood pressure Blood pressure (BP) is the pressure Pressure (symbol: ''p'' or ''P'') is the force In physics Physics (fr ...
. It is part of a body negative feedback loop in which the body tries to restore homeostasis (maintain constant internal environment). For example, vasoconstriction is a hypothermic preventative in which the blood vessels constrict and blood must move at a higher pressure to actively prevent a hypoxic reaction.
ATP ATP may refer to: Companies and organizations * Association of Tennis Professionals * American Technical Publishers * ', a Danish pension * Armenia Tree Project * Association for Transpersonal Psychology * ATP architects engineers office * ATP ...

ATP
is used as a form of energy to increase this pressure to heat the body. Once homeostasis is restored, the blood pressure and ATP production regulates. Vasoconstriction also occurs in superficial blood vessels of warm-blooded animals when their ambient environment is cold; this process diverts the flow of heated blood to the center of the animal, preventing the loss of heat.


Pathology

Vasoconstriction can be a contributing factor to
erectile dysfunction Erectile dysfunction (ED), also called impotence, is the type of sexual dysfunction Sexual dysfunction is difficulty experienced by an individual or partners during any stage of normal Human sexual activity, sexual activity, including physical ...

erectile dysfunction
.Richard Milsten and Julian Slowinski, ''The sexual
male Male (symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male organism cannot sexual reproduction, reproduce sexually ...

male
'', bc, main point W.W. Norton Company, New York, London (1999)
An increase in blood flow to the penis causes an erection. Improper vasoconstriction may also play a role in secondary
hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not ...

hypertension
.


See also

*
Addison's disease
Addison's disease
*
Inotrope An inotrope is an agent that alters the force or energy of muscular contractions. Negatively inotropic agents weaken the force of muscular contractions. Positively inotropic agents increase the strength of muscular contraction. The term ''inotr ...
*
Hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not ...

Hypertension
*
Nitric oxide Nitric oxide (nitrogen oxide or nitrogen monoxide) is a colorless gas with the formula . It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its che ...

Nitric oxide
*
Pheochromocytoma Pheochromocytoma (PHEO or PCC) is a rare tumor of the adrenal medulla composed of chromaffin cells, also known as pheochromocytes. When a tumor composed of the same cells as a pheochromocytoma develops outside the adrenal gland, it is referred t ...

Pheochromocytoma
* Shock *
Vasodilation Vasodilation is the widening of blood vessel The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. ...

Vasodilation
*
Postural orthostatic tachycardia syndrome Postural orthostatic tachycardia syndrome (POTS) is a condition in which a change from lying A lie is an assertion that is believed to be false, typically used with the purpose of deceiving someone. The practice of communicating lies is c ...
*
Hemostasis Hemostasis or haemostasis is a process to prevent and stop bleeding, meaning to keep blood within a damaged blood vessel The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vess ...


References


External links


Definition of Vasoconstriction on HealthScout

Cannabis arteritis revisited--ten new case reports


* ttp://www.druglibrary.org/schaffer/hemp/medical/cannabin1.htm Vasoconstrictor effects of Cannabis appear to inhibit Migraine (headache) attacks {{Cardiovascular physiology Cardiovascular physiology