Ch 44: Osmoregulation

Ureter

A duct leading from the kidney to the urinary bladder

Renal Pelvis

The funnel-shaped chamber that receives processed filtrate from the vertebrate kidney’s collecting ducts and is drained by the ureter.

Malpighian Tubule

A unique execratory organ of insects that empties into the digestive tract, removes nitrogenous wastes from the hemolymph and functions in osmoregulation

Cortical Nephron

In mammals and birds, a nephron with a loop of Henle located almost entirely in the renal cortex

Metanephridium

(plural, metanephridia) an excratory organ found in many invertebrates that typically consists of tubules connecting ciliated internal openings to external opeenings

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 kidneys alter ion and water movement and reduce blood pressure

Uric Acid

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 in water

Peritubular Capillary

One of the tiny blood vessels that form a network surrounding the proximal and distal tubules in the kidney

Osmoregulation

Regulation of solute concentrations and water balance by a cell or organism

Renal Cortex

The outer portion of the vertebrate kidney

Excretion

The disposal of nitrogen-containing metabolites and other waste products

Urinary Bladder

The pouch where urine is stored prior to elimination

Reabsorption

In excretory systems, the recovery of solutes and water from filtrate

Ammonia

A small, toxic molecule (NH3) produced by nitrogen fixation or as a metabolic waste product of protein and nucleic acid metabolism

Filtration

In excretory systems, the extraction of water and small solutes, including metabolic wastes, from the body fluid

Bowman’s Capsule

A cup-shaped receptacle in the vertebrate kidney that is in the initial, expanded segment of the nephron, where filtrate enters the blood

Juxtaglomerular Apparatus (jGA)

A specialized tissue in nephrons that release the enzyme renin in response to a drop in blood volume or pressure

Antidiuretic Hormone (ADH)

A peptide hormone, also called vasopressin, that promotes water retention by the kidneys, Produced in the hypothalamus and released from the posterior pituitary, ADH also functions in the brain

Collecting Duct

The location in the kidney where processed filtrate, called urine. is collected from the renal tubules

Protonephridium

(plural, protonephridia) an excretory system, such as the flame bulb system of flatworms, consisting of a network of tubules lacking internal openings

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

Distal Tubule

In the vertebrate kidney, the portion of a nephron that helps refine filtrate and empties it into a collecting duct

Osmoregulator

An animal that controls its internal osmolarity independent of the external enviroment

Countercurrent Multiplier System

A countercurrent system in which energy is expanded in active transport to facilitate exchange of materials and generate concentration gradients

Glomerulus

A ball of capillaries surrounded by Bowman’s capsule in the nephron and serving as the site of filtration in the vertebrate kidney

Kidney

In vertebrates, one of a pair of excretory organs where blood filtrate is formed and proccessed into urine

Proximal Tubule

In the vertebrate kidney, the portion of a nephron immediately downstream from Bowman’s capsule that conveys and helps refine filtrate

Juxtamedullary Nephron

In mammals and birds, a nephron with a loop of Henle that extends far into the renal medulla

Transport Epithelium

One or more layers of specialized epithelial cells that carry out and regulate solute movement

Renin-Angiotensin-Aldosterone System (RAAS)

A hormone cascade pathway that helps regulate blood pressure and blood volume

Secretion

(1) the discharge of molecules synthesized by a cell
(2) the active transport of wastes and certain other solutes from the body fluid into the filtrate in an excretory system

Filtrate

Cell-free fluid extracted from the body fluid by the excretory system

Urea

A soluble nitrogenous waste produced in the liver by a metabolic cycle that combines ammonia with carbon dioxide

Renal Medulla

The inner portion of the vertebrate kidney, beneath the renal cortex

Nephron

The tubular excretory unit of the vertebrate kidney

Vasa Recta

The capillary system in the kidney that serves the loop of Henle

Anhydrobiosis

A dormant state involving loss of almost all body water

Osmoconformer

An animal that is isoosmotic with its enviroment

Urethra

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

Osmolarity

Solute concentration expressed as molarity