Kidney and Digestive System: Key Terms and Concepts for Biology

Countercurrent Multiplier System

Interaction between descending limb and ascending limb of the loop of Henle resulting in multiplication of the solute concentration in the interstitial fluid

Urea

Main nitrogenous waste product

Aquaporin

Protein channel that permits osmosis to occur; can be inserted into cell membrane in response to stimulation by ADH

Secretion

Transport of a substance from the blood into the nephron tubule

Vasopressin

Otherwise known as antidiuretic hormone

Aldosterone

Principal corticosteroid hormone involved in regulation of electrolyte balance

Reabsorption

Transport of a substance from the lumen of a nephron into the peritubular capillaries

Glomeruli

Tufts of capillaries that filter fluid into the kidney tubules

Peritubular Capillaries

Reabsorption of filtrate to blood supply, drains to veins leaving the kidney

Afferent Arteriole

Carry blood toward glomerulus

Efferent Arteriole

Carry blood away from glomerulus

Absorption

Transport of molecules across epithelial membranes into the body fluids

Digestion

Process of converting food into molecules that can be absorbed through the intestine into the blood

Motility

The ability to mix contents and move them from the oral to anal end of the GI tract by muscular contractions

Peristalsis

Waves of smooth muscle contraction; serves to propel the contents of the digestive tract in one direction

Chyme

Mixture of partially digested food and digestive juices that passes from the stomach into the duodenum

H/K Atpase Pump

Transport H+ against concentration gradient into the stomach while transport K+ in opposite direction

Segmentation

Major contractile activity of the small intestine

Hepatocytes

Liver cells

Bile Salt

Act to emulsify fat in the lumen of the small intestine

Micelles

Colloidal particle formed by the aggregation of numerous molecules

Amylase

Digestive enzyme of carbohydrates

Trypsin

Protein digesting enzyme

Lipase

Digests triglycerides

Emulsification

Process of producing an emulsion derived from fat globules

Bilirubin

Yellow substance resulting from heme breakdown; excreted in bile as a bile pigment

Enterohepatic Circulation

Recirculation of a compound between liver and small intestine