Baroreceptor

Information about Baroreceptor

Baroreceptors (or baroceptors) in the human body detect the pressure of blood flowing through them, and can send messages to the central nervous system to increase or decrease total peripheral resistance and cardiac output.

Baroreceptors can be divided into two categories, high pressure arterial baroreceptors and low pressure baroreceptors (also known as cardiopulmonary receptors).

Arterial baroreceptors

There are baroreceptors present in the arch of the aorta, and the carotid sinuses of the left and right internal carotid arteries. In some sensitive people, due to baroreceptors, vigorous palpation of a carotid artery can cause severe bradycardia or even cardiac arrest.

Baroreceptors act to maintain mean arterial blood pressure to allow tissues to receive the right amount of blood.

See main article Baroreflex

If blood pressure falls, such as in shock, baroreceptor firing rate decreases. Signals from the carotid baroreceptors are sent via the glossopharyngeal nerve (cranial nerve IX). Signals from the aortic baroreceptors travel through the vagus nerve (cranial nerve X). Baroreceptors work by detecting the amount of stretch. The more the baroreceptor walls are stretched, the more frequently they generate action potentials. The arterial baroreceptors have a lower threshold of around 70 mmHg (typical arterial blood pressure is around 80-90 mmHg). Below this the receptors stop firing signals completely, any further decrease in pressure will cause no additional effect. At this low pressure however the response of chemoreceptors becomes more vigorous, especially below 60 mmHg.

Baroreceptors respond very quickly to maintain a stable blood pressure, but they only respond to short term changes. Over a period of days or weeks they will reset to a new value. Thus, in people with essential hypertension the baroreceptors behave as if the elevated blood pressure is normal and aim to maintain this high blood pressure.

Low pressure baroreceptors

These are veins and in the walls of the atria of the heart. The low pressure baroreceptors are involved with the regulation of blood volume. The blood volume determines the mean pressure throughout the system, in particular in the venous side where most of the blood is held.

The low pressure baroreceptors have both circulatory and renal effects, they produce changes in hormone secretion which have profound effects on the retention of salt and water and also influence intake of salt and water. The renal effects allow the receptors to change the mean pressure in the system in the long term.

Denervating these recept ors 'fools' the body into thinking that we have too low blood volume and initiates mechanisms which retain fluid and so push up the blood pressure to a higher level than we would otherwise have.

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Nervous system, receptors: somatosensory system
Medial lemniscus
Spinothalamic tract
The human body is the entire physical structure of a human organism. The human body consists of a head, neck, torso, two arms and two legs. The average height of an adult human is about 1.6 m (5 to 6 feet) tall. This size is largely determined by genes.
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The central nervous system (CNS) represents the largest part of the nervous system, including the brain and the spinal cord. Together with the peripheral nervous system, it has a fundamental role in the control of behavior.
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Total peripheral resistance refers to the cumulative resistance of the thousands of arterioles in the body, or the lungs, respectively. It is approximately equal to the resistance of the arterioles, since the arterioles are the chief resistance vessels in the body.
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Cardiac output (CO) is the volume of blood being pumped by the heart, in particular by a ventricle in a minute.

Normal Output

Cardiac output is equal to the stroke volume (SV) multiplied by the heart rate (HR).
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The aorta (generally pronounced [eɪˈɔːtə] or "ay-orta") is the largest artery in the human body, originating from the left ventricle of the heart and bringing oxygenated blood to all parts of the body in the systemic circulation.
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In human anatomy, the internal carotid artery is a major artery of the head and neck that helps supply blood to the brain.

Classification

Terminologia Anatomica currently breaks the artery into four parts: "cervical", "petrous", "cavernous", and "cerebral".
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Palpation is used as part of a physical examination in which an object is felt (usually with the hands of a healthcare practitioner) to determine its size, shape, firmness, or location.
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Bradycardia
Classifications and external resources

ICD-10 R 00.1
ICD-9 427.81 , 659.7 , 785.9 , 779.81

Bradycardia, as applied to adult medicine, is defined as a resting heart rate of under 60 beats per minute, though it is seldom symptomatic
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Cardiac arrest
Classification & external resources

ICD-10 I 46.
ICD-9 427.5

A cardiac arrest, also known as cardiorespiratory arrest, cardiopulmonary arrest or circulatory arrest
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The mean arterial pressure (MAP) is a term used in medicine to describe a notional average blood pressure in an individual. It is defined as the average arterial pressure during a single cardiac cycle.
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In cardiovascular physiology, the baroreflex or baroreceptor reflex is one of the body's homeostatic mechanisms for maintaining blood pressure. It provides a negative feedback loop in which an elevated blood pressure reflexively causes blood pressure to decrease; similarly,
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Shock
Classification & external resources

ICD-10 many incl. R 57.
ICD-9 785

DiseasesDB 12013
MedlinePlus 000039
eMedicine emerg/531   med/285 emerg/533

MeSH D012769

For other uses, see Shock.

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The glossopharyngeal nerve is the ninth of twelve pairs of cranial nerves. It exits the brainstem out from the sides of the upper medulla, just rostral (closer to the nose) to the vagus nerve.
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Cranial nerves are nerves that emerge directly from the brain in contrast to spinal nerves which emerge from segments of the spinal cord. Although thirteen cranial nerves in humans fit this description, twelve are conventionally recognized.
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The vagus nerve (also called pneumogastric nerve or cranial nerve X) is the tenth of twelve paired cranial nerves, and is the only nerve that starts in the brainstem (within the medulla oblongata) and extends, through the jugular foramen, down below the head, to the
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Cranial nerves are nerves that emerge directly from the brain in contrast to spinal nerves which emerge from segments of the spinal cord. Although thirteen cranial nerves in humans fit this description, twelve are conventionally recognized.
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An action potential is a "spike" of electrical discharge that travels along the membrane of a cell. Action potentials are an essential feature of animal life, rapidly carrying information within and between tissues. They also occur in some plants.
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Blood pressure (strictly speaking: vascular pressure) refers to the force exerted by circulating blood on the walls of blood vessels, and constitutes one of the principal vital signs.
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A chemosensor, also known as chemoreceptor, is a cell or group of cells that transduce a chemical signal into an action potential. Or, more generally, a chemosensor detects certain chemical stimuli in the environment.
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Hypertension
Classification & external resources

ICD-10 I 10. ,I 11. ,I 12. ,
I 13. ,I 15.
ICD-9 401.x

OMIM 145500
DiseasesDB 6330
MedlinePlus 000468
eMedicine med/1106   ped/1097 emerg/267


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vein is a blood vessel that carries blood toward the heart. The majority of veins in the body carry low-oxygen blood from the tissues back to the heart; the exceptions being the pulmonary and umbilical veins which both carry oxygenated blood.
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heart is a muscular organ responsible for pumping blood through the blood vessels by repeated, rhythmic contractions, or a similar structure in the annelids, mollusks, and arthropods.
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hormone (from Greek όρμή - "to set in motion") is a chemical messenger that carries a signal from one cell (or group of cells) to another. All multicellular organisms produce hormones (including plants - see phytohormone).
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Osmoregulation is the active regulation of the osmotic pressure of bodily fluids to maintain the homeostasis of the body's water content; that is it keeps the body's fluids from becoming too dilute or too concentrated.
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Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed
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nervous system of an animal coordinates the activity of the muscles, monitors the organs, constructs and also stops input from the senses, and initiates actions. Prominent parts of a nervous system include neurons and nerves, which are used in coordination.
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In a sensory system, a sensory receptor is a structure that recognizes a stimulus in the internal or external environment of an organism. In response to stimuli the sensory receptor initiates sensory transduction by creating graded potentials or action potentials in the same cell
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Somatic sensation consists of the various sensory receptors that trigger the experiences labelled as touch or pressure, temperature (warm or cold), pain (including itch and tickle), and the sensations of muscle movement and joint position including posture, movement, and facial
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The medial lemniscus, also known as Reil's band or Reil's ribbon, is a pathway in the brainstem that carries sensory information from the gracile and cuneate nuclei to the thalamus.
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A mechanoreceptor is a sensory receptor that responds to mechanical pressure or distortion. There are four main types in the glabrous skin of humans: Pacinian corpuscles, Meissner's corpuscles, Merkel's discs, and Ruffini corpuscles.
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