kinetics

DEFINITION:

The branch of dynamics that pertains to the turnover, or rate of change, of a specific factor (e.g., erythrocytes-erythrokinetics, leukocytes-leukokinetics, or iron-ferrokinetics), commonly expressed as units of amount per unit time.

regulation

DEFINITION:

1. The act of adjusting or state or being adjusted to a certain standard.
2. In biology, the adaptation of form or behavior of an organism to changed conditions.
3. The power to form a whole embryo from stages before the gastrula.

water channels

DEFINITION:

Channels in a cell membrane that permit passage of water molecules; chemical substances such as vasopressin cause the opening of new channels and increase permeability.

urea

DEFINITION:

A soluble weakly basic nitrogenous compound CO(NH₂)₂ that is the chief solid component of mammalian urine and an end product of protein decomposition, is synthesized from carbon dioxide and ammonia, and is used especially in synthesis (as of resins and plastics) and in fertilizers and animal rations.

IMCD

DEFINITION:

Inner medullary collecting duct.

vasopressin

DEFINITION:

1. One of two octapeptide hormones formed by the neuronal cells of the hypothalamic nuclei and stored in the posterior lobe of the pituitary gland (neurohypophysis), the other being oxytocin. It stimulates the contraction of the muscular tissue of the capillaries and arterioles, raising the blood pressure. It promotes contraction of the intestinal musculature and increases peristalsis, and also exerts some contractile influence on the uterus. It also has a specific effect on the epithelial cells of the distal portion of the uriniferous tubule, augmenting resorption of water independently of solutes, resulting in concentration of urine and dilution of blood serum. Its rate of secretion is regulated chiefly by the osmolarity of the plasma.

2. [USP], A pharmaceutical preparation of the same principle, prepared synthetically or obtained from the posterior pituitary of healthy domestic animals used for food by man; used mainly as an antidiuretic in the treatment of acute or chronic diabetes insipidus, administered intramuscularly as a test of hypothalamo-neurohypophysial-renal function in distinguishing central from nephrogenic diabetes insipidus; it may also be used to stimulate smooth muscle tissue, especially to induce vasoconstriction in the presence of hemorrhage. Called also antidiuretic hormone (ADH).

AVP

DEFINITION:

Arginine vasopressin.

osmotic water permeability

DEFINITION:

The ability to channel water across a membrane in response to a concentration gradient.

urea

DEFINITION:

A soluble weakly basic nitrogenous compound CO(NH₂)₂ that is the chief solid component of mammalian urine and an end product of protein decomposition, is synthesized from carbon dioxide and ammonia, and is used especially in synthesis (as of resins and plastics) and in fertilizers and animal rations.

AVP

DEFINITION:

Arginine vasopressin.

urea

DEFINITION:

A soluble weakly basic nitrogenous compound CO(NH₂)₂ that is the chief solid component of mammalian urine and an end product of protein decomposition, is synthesized from carbon dioxide and ammonia, and is used especially in synthesis (as of resins and plastics) and in fertilizers and animal rations.

kinetics

DEFINITION:

The branch of dynamics that pertains to the turnover, or rate of change, of a specific factor (e.g., erythrocytes-erythrokinetics, leukocytes-leukokinetics, or iron-ferrokinetics), commonly expressed as units of amount per unit time.

transport

DEFINITION:

The movement of materials in biological systems, particularly into and out of cells and across epithelial layers.

activation

DEFINITION:

1. The act or process of rendering active.

2. The transformation of a proenzyme into an active enzyme by the action of a kinase or another proenzyme.

3. Gain in the purifying of sewage by means of activated sludge.

4. The process by which the central nervous system is stimulated into activity through the mediation of the reticular activating system.

5. The deliberate induction of a pattern of electrical activity in the brain in electroencephalography.

permeability

DEFINITION:

The state of being penetrable, esp. having pores or openings that permit liquids or gases to pass through.

transporters

DEFINITION:

Transport proteins; often specifically a transport protein that after binding one to several molecules of substrate, undergoes a conformational change that moves only the substrate across the membrane. Different types facilitate movement with (symport) and against (antiport) concentration gradients.

permeability

DEFINITION:

The state of being penetrable, esp. having pores or openings that permit liquids or gases to pass through.

lumen

DEFINITION:

1. The cavity or channel within a tube or tubular organ.
2. The unit of luminous flux: it is the flux emitted in a solid angle of one steradian by a uniform point source with luminous intensity of one candela.

rate

DEFINITION:

1. The amount of change of a physical quantity or number of occurrences of an event per unit time.

2. In epidemiology and demography, the frequency of an event in a specified population; correctly applied only to fractions for which all of the cases contributing to the numerator are also counted in the denominator and for which the denominator is the entire population at risk. Rates are often multiplied by a factor to give the number of events per 1000, 10,000, or 100,000 population.

3. More generally, a term sometimes used to denote some measured quantity with respect to another. Symbol R.

apical

DEFINITION:

Pertaining to or located at the apex.

endocytosis

DEFINITION:

The uptake by a cell of material from the environment by invagination (infolding) of its plasma membrane; it includes both phagocytosis and pinocytosis.

collecting ducts

DEFINITION:

Renal collecting tubules: the arcuate renal tubule, straight collecting tubule, and papillary duct considered together.

lumen

DEFINITION:

1. The cavity or channel within a tube or tubular organ.
2. The unit of luminous flux: it is the flux emitted in a solid angle of one steradian by a uniform point source with luminous intensity of one candela.

gradient

DEFINITION:

1. The increase or decrease of one variable expressed as a function of a second.

2. The graphic representation of such a change.

kinetics

DEFINITION:

The branch of dynamics that pertains to the turnover, or rate of change, of a specific factor (e.g., erythrocytes-erythrokinetics, leukocytes-leukokinetics, or iron-ferrokinetics), commonly expressed as units of amount per unit time.

AVP

DEFINITION:

Arginine vasopressin.

washout

DEFINITION:

A cleansing or sweeping clean.

AVP

DEFINITION:

Arginine vasopressin.

lumen

DEFINITION:

1. The cavity or channel within a tube or tubular organ.
2. The unit of luminous flux: it is the flux emitted in a solid angle of one steradian by a uniform point source with luminous intensity of one candela.

affect

DEFINITION:

1. To produce an effect on; influence.

2. The external expression of emotion attached to ideas or mental representations of objects.

phase

DEFINITION:

1. The view that a thing presents to the eye.
2. Any one of the varying aspects or stages through which a disease or process may pass.
3. In physical chemistry, any physically or chemically distinct, homogeneous, and mechanically separable part of a system.
4. On an electrodiagnostic recording, that portion of a wave that is between any two consecutive times it crosses the baseline.

AVP

DEFINITION:

Arginine vasopressin.

lumen

DEFINITION:

1. The cavity or channel within a tube or tubular organ.
2. The unit of luminous flux: it is the flux emitted in a solid angle of one steradian by a uniform point source with luminous intensity of one candela.

urea

DEFINITION:

A soluble weakly basic nitrogenous compound CO(NH₂)₂ that is the chief solid component of mammalian urine and an end product of protein decomposition, is synthesized from carbon dioxide and ammonia, and is used especially in synthesis (as of resins and plastics) and in fertilizers and animal rations.

AVP

DEFINITION:

Arginine vasopressin.

washout

DEFINITION:

A cleansing or sweeping clean.

physical processes

DEFINITION:

The series of operations, events, or steps leading to the achievement of specific results within the body, in material things, or in physics.

AVP

DEFINITION:

Arginine vasopressin.

mediated

DEFINITION:

Accomplished by the aid of an intervening medium.

alteration

DEFINITION:

1. The act of making different.

2. Castration, spaying.

water channel

DEFINITION:

A channel in the plasma membrane of plant and animal cells that permits passage of water molecules; chemical substances such as vasopressin cause the opening of new channels and increase permeability.

apical membrane

DEFINITION:

See under membrane.