Blood pressure in the context of "Infrared sauna"

Hydrostatics is the branch of fluid mechanics that studies fluids at hydrostatic equilibrium and "the pressure in a fluid or exerted by a fluid on an immersed body". The word "hydrostatics" is sometimes used to refer specifically to water and other liquids, but more often it includes both gases and liquids, whether compressible or incompressible. It encompasses the study of the conditions under which fluids are at rest in stable equilibrium. It is opposed to fluid dynamics, the study of fluids in motion.

Hydrostatics is fundamental to hydraulics, the engineering of equipment for storing, transporting and using fluids. It is also relevant to geophysics and astrophysics (for example, in understanding plate tectonics and the anomalies of the Earth's gravitational field), to meteorology, to medicine (in the context of blood pressure), and many other fields.

The renin–angiotensin system (RAS), or renin–angiotensin–aldosterone system (RAAS), is a hormone system that regulates blood pressure, fluid, and electrolyte balance, and systemic vascular resistance.

When renal blood flow is reduced, juxtaglomerular cells in the kidneys convert the precursor prorenin (already present in the blood) into renin and secrete it directly into the circulation. Plasma renin then carries out the conversion of angiotensinogen, released by the liver, to angiotensin I, which has no biological function on its own. Angiotensin I is subsequently converted to the active angiotensin II by the angiotensin-converting enzyme (ACE) found on the surface of vascular endothelial cells, predominantly those of the lungs. Angiotensin II has a short life of about 1 to 2 minutes. Then, it is rapidly degraded into angiotensin III by angiotensinases which are present in red blood cells and vascular beds in many tissues.

The kidneys are a pair of organs of the excretory system in vertebrates, which maintain the balance of water and electrolytes in the body (osmoregulation), filter the blood, remove metabolic waste products, and, in many vertebrates, also produce hormones (in particular, renin) and maintain blood pressure. In healthy vertebrates, the kidneys maintain homeostasis of extracellular fluid in the body. When the blood is being filtered, the kidneys form urine, which consists of water and excess or unnecessary substances, the urine is then excreted from the body through other organs, which in vertebrates, depending on the species, may include the ureter, urinary bladder, cloaca, and urethra.

All vertebrates have kidneys. The kidneys are the main organ that allows species to adapt to different environments, including fresh and salt water, terrestrial life and desert climate. Depending on the environment in which animals have evolved, the functions and structure of the kidneys may differ. Also, between classes of animals, the kidneys differ in shape and anatomical location. In mammals, they are usually bean-shaped. Evolutionarily, the kidneys first appeared in fish as a result of the independent evolution of the renal glomeruli and tubules, which eventually united into a single functional unit. In some invertebrates, the nephridia are analogous to the kidneys but nephridia are not kidneys. The metanephridia, together with the vascular filtration site and coelom, are functionally identical to the ancestral primitive kidneys of vertebrates.

Anger is an intense emotional state involving a strong, uncomfortable and non-cooperative response to a perceived provocation, hurt, or threat.

A person experiencing anger will often experience physical effects, such as increased heart rate, elevated blood pressure, and increased levels of the stress hormones adrenaline and noradrenaline. Some view anger as an emotion that triggers part of the fight or flight response. Anger becomes the predominant feeling behaviorally, cognitively, and physiologically when a person makes the conscious choice to take action to immediately stop the threatening behavior of another outside force.

Guillain–Barré syndrome (GBS) is a rapid-onset muscle weakness caused by the immune system damaging the peripheral nervous system. Typically, both sides of the body are involved, and the initial symptoms are changes in sensation or pain often in the back along with muscle weakness, beginning in the feet and hands, often spreading to the arms and upper body. The symptoms may develop over hours to a few weeks. During the acute phase, the disorder can be life-threatening, with about 15% of people developing respiratory muscle weakness requiring mechanical ventilation. Some are affected by changes in the function of the autonomic nervous system, which can lead to dangerous abnormalities in heart rate and blood pressure.

Although the cause is unknown, the underlying mechanism involves an autoimmune disorder in which the body's immune system mistakenly attacks the peripheral nerves and damages their myelin insulation. Sometimes this immune dysfunction is triggered by an infection or, less commonly, by surgery, and by vaccination. The diagnosis is usually based on the signs and symptoms through the exclusion of alternative causes and supported by tests such as nerve conduction studies and examination of the cerebrospinal fluid. There are several subtypes based on the areas of weakness, results of nerve conduction studies, and the presence of certain antibodies. It is classified as an acute polyneuropathy.

The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the brainstem. It is anterior and partially inferior to the cerebellum. It is a cone-shaped neuronal mass responsible for autonomic (involuntary) functions, ranging from vomiting to sneezing. The medulla contains the cardiovascular center, the respiratory center, vomiting and vasomotor centers, responsible for the autonomic functions of breathing, heart rate and blood pressure as well as the sleep–wake cycle. "Medulla" is from Latin, ‘pith or marrow’. And "oblongata" is from Latin, ‘lengthened or longish or elongated'.

During embryonic development, the medulla oblongata develops from the myelencephalon. The myelencephalon is a secondary brain vesicle which forms during the maturation of the rhombencephalon, also referred to as the hindbrain.

The stethoscope, from Ancient Greek στῆθος (stêthos), meaning "breast", and σκοπέω (skopéō), meaning "to look", is a medical device for auscultation, or listening to internal sounds of an animal or human body. It typically has a small disc-shaped resonator that is placed against the naked skin, with either one or two tubes connected to two earpieces. A stethoscope can be used to listen to the sounds made by the heart, lungs or intestines, as well as blood flow in arteries and veins. In combination with a manual sphygmomanometer, it is commonly used when measuring blood pressure. It was invented in 1816 by René Laennec and the binaural version by Arthur Leared in 1851.

A stethoscope that intensifies auscultatory sounds is called a phonendoscope.

A millimetre of mercury is a manometric unit of pressure, formerly defined as the extra pressure generated by a column of mercury one millimetre high. Currently, it is defined as exactly 133.322387415 pascals, or approximately 1 torr = ⁠1/760⁠ atmosphere = ⁠101325/760⁠ pascals. It is denoted mmHg or mm Hg.

Although not an SI unit, the millimetre of mercury is still often encountered in some fields; for example, it is still widely used in medicine, as demonstrated for example in the medical literature indexed in PubMed. For example, the U.S. and European guidelines on hypertension, in using millimeters of mercury for blood pressure, are reflecting the fact (common basic knowledge among health care professionals) that this is the usual unit of blood pressure in clinical medicine.