Glossary of Physiology Terms – B

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Ball and chain model
Biconcave
Bicuspid valve
BMI
Body mass index

Ball and chain model

Definition:

Proposed model for the inactivation of some voltage-gated ion channels. According to this model, after channel opening, the pore of the open channel is plugged by a globular cytoplasmic portion of the channel protein. The globular portion (ball of amino acids) is tethered to the rest of the protein by a linker part (chain of amino acids).

Related glossary terms/phrases:

Channel inactivation

Biconcave

Definition:

Concave on both sides of a structure, usually referring to a disc or a lens.

Of particular importance to physiology is the structure of mature red blood cells (erythrocytes), which is a flattened cell that has assume a biconcave shape. It is thought that the biconcave shape of red blood cells helps with the flow property of blood through blood vessels.

Bicuspid valve

Definition:

The one-way valve between the left atrium and left ventricle of the heart. It is also known as the left atrioventricular valve or mitral valve.

The direction of blood flow through the bicuspid valve is from the left atrium to the left ventricle.

Related glossary terms/phrases:

Left atrioventricular valve
Mitral valve

BMI

Definition:

Body mass index

See:

Body mass index

Abbreviation:

BMI

Definition:

The body mass index is measured by dividing body weight (in kilograms) by body height (in meters) squared (kg / m²). It is highly correlated with body composition, and higher BMI values are correlated with higher body fat content. The BMI value is used to classify one's weight in several categories including underweight, normal, overweight, and obese. The range of BMI values considered to be normal is 18.5 to 24.9. Higher BMI values are associated with an increased risk for diseases such as diabetes mellitus type II, hypertension, and cardiovascular disease.