A steroid hormone that acts on tubules of the kidney to regulate the transport of sodium ions (Na+) and potassium ions (K+).
A small, very toxic molecule (NH3) produced by nitrogen fixation or as a metabolic waste product of protein and nucleic acid metabolism.
A peptide hormone that stimulates constriction of precapillary arterioles and increases reabsorption of NaCl and water by the proximal tubules of the kidney, increasing blood pressure and volume.
antidiuretic hormone (ADH)
A peptide hormone, also known as vasopressin, that promotes water retention by the kidneys. Produced in the hypothalamus and released from the posterior pituitary, ADH also has activities in the brain.
A channel protein in the plasma membrane of a plant, animal, or microorganism cell that specifically facilitates osmosis, the diffusion of water across the membrane.
atrial natriuretic peptide (ANP)
A peptide hormone secreted by cells of the atria of the heart in response to high blood pressure. ANP's effects on the kidney alter ion and water movement and thereby reduce blood pressure.
A cup-shaped receptacle in the vertebrate kidney that is the initial, expanded segment of the nephron where filtrate enters from the blood.
The location in the kidney where processed filtrate, called urine, is collected from the renal tubules.
In mammals and birds, a nephron with a loop of Henle located almost entirely in the renal cortex.
countercurrent multiplier system
A countercurrent system in which energy is expended in active transport to facilitate exchange of materials and generate concentration gradients.
In the vertebrate kidney, the portion of a nephron that helps refine filtrate and empties it into a collecting duct.
In excretory systems, the extraction of water and small solutes, including metabolic wastes, from the body fluid.
A ball of capillaries surrounded by Bowman's capsule in the nephron and serving as the site of filtration in the vertebrate kidney.
The ventral part of the vertebrate forebrain; functions in maintaining homeostasis, especially in coordinating the endocrine and nervous systems; secretes hormones of the posterior pituitary and releasing factors that regulate the anterior pituitary.
Referring to a solution that, when surrounding a cell, has no effect on the passage of water into or out of the cell.
juxtaglomerular apparatus (JGA)
A specialized tissue in nephrons that releases the enzyme renin in response to a drop in blood pressure or volume.
In mammals and birds, a nephron with a loop of Henle that extends far into the renal medulla.
loop of Henle
The hairpin turn, with a descending and ascending limb, between the proximal and distal tubules of the vertebrate kidney; functions in water and salt reabsorption.
A unique excretory organ of insects that empties into the digestive tract, removes nitrogenous wastes from the hemolymph, and functions in osmoregulation.
(plural, metanephridia) An excretory organ found in many invertebrates that typically consists of tubules connecting ciliated internal openings to external openings.
An animal that controls its internal osmolarity independent of the external environment.
One of the tiny blood vessels that form a network surrounding the proximal and distal tubules in the kidney.
An endocrine gland at the base of the hypothalamus; consists of a posterior lobe (neurohypophysis), which stores and releases two hormones produced by the hypothalamus, and an anterior lobe (adenohypophysis), which produces and secretes many hormones that regulate diverse body functions.
An excretory system, such as the flame bulb system of flatworms, consisting of a network of tubules lacking internal openings.
In the vertebrate kidney, the portion of a nephron immediately downstream from Bowman's capsule that conveys and helps refine filtrate.
One of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring fused to a five-membered ring. Adenine (A) and guanine (G) are purines.
The funnel-shaped chamber that receives processed filtrate from the vertebrate kidney's collecting ducts and is drained by the ureter.
renin-angiotensin-aldosterone system (RAAS)
A hormone cascade pathway that helps regulate blood pressure and blood volume.
(1) The discharge of molecules synthesized by a cell. (2) The discharge of wastes from the body fluid into the filtrate.
One or more layers of specialized epithelial cells that regulate solute movements.
A soluble nitrogenous waste produced in the liver by a metabolic cycle that combines ammonia with carbon dioxide.
A tube that releases urine from the mammalian body near the vagina in females and through the penis in males; also serves in males as the exit tube for the reproductive system.
A product of protein and purine metabolism and the major nitrogenous waste product of insects, land snails, and many reptiles. Uric acid is relatively nontoxic and largely insoluble.