Renal Definitions Flashcards
Ultra-filtrate
a solute that has been passed through a semipermeable membrane with very small pores. Usually contains only low-molecular-weight solutes.
Nephron
a structural and functional unit of the kidney, resembling a microscopic funnel with a long stem and two convoluted sections. Each kidney contains about 1.25 million nephrons, each consisting of the renal corpuscle, the loop of Henle, and the renal tubules.
Glomerulus
a tuft or cluster, a structure composed of blood vessels or nerve fibers, such as a renal glomerulus
Tubules
a small tube, such as one of the collecting tubules in the kidneys, can be broken into functionally different segments: proximal convoluted tubule, loop of Henle, distal tubule, and collecting duct
Proximal convoluted tubule
highly coiled
Loop of Henle
the U-shaped potion of a renal tubule, consisting of a thin descending limb and a thick ascending limb
Distal Tubule
part of the tubules
Collecting duct
part of the tubules
Bowmans capsule
the cup-shaped end of a renal tubule containing a glomerulus, membrane structure
Collecting tubules
any one of the many relatively large straight tubules of the kidney that funnel urine into the real pelvis. The collecting tubules drain the urine from the distal convoluted tubules in the renal cortex and descend into the renal medulla before connecting with each other at various intervals along the path to the renal pelvis. The collecting tubules play an important role in maintaining the fluid balance of the body by allowing water to osmose through their membranes into the interstitial fluid in the renal medulla. Antidiuretic hormone in the blood makes the collecting tubules permeable to water. If no antidiuretic hormone is present in the blood, membranes of the collecting tubules are practically impermeable to water.
Renal pelvis
a funnel-shaped dilation that drains urine from the kidney into the ureter
Ureter
one of a pair of tubes that carries urine from the kidney into the bladder
Bladder
a membranous sac serving as a receptacle for secretions
Inner Medulla
a part of the parenchyma of the kidney, beneath the cortex, including the renal pyramids and columns
Outer Cortex
the outer layer of a body organ
Solute Load
the end waste products of metabolism
Antidiuretic Hormone (ADH)
a hormone that decreases the production of urine by increasing the reabsorption of water by the renal tubules. ADH is secreted by cells of the hypothalamus and stored in the posterior lobe of the pituitary gland. It is released in response to a decrease in blood volume or an increased concentration of sodium or other substances in plasma, or by pain, stress, or the action of certain drugs. ADH can cause contraction of smooth muscle in the digestive tract and blood vessels, especially capillaries, arterioles, and venules
Oliguria
the condition of having urinary volumes of less than 500 mL/day
Azotemia
the accumulation in the blood of abnormal quantities of urea, uric acid, creatinine, and other nitrogenous wastes
Renal Function
the ability of the kidney to adequately eliminate nitrogenous waste products
Renal Failure
the inability of a kidney to excrete the daily load of wastes
Renin-Angiotensin mechanism
a major control of blood pressure involving kidney-secreted renin that acts in the plasma to form angiotensin I, which is converted to angiotensin II, a powerful vasoconstrictor and potent stimulus of aldosterone secretion by the adrenal gland
Juxtaglomerular appartus
cells of glomerulus
Renin
a proteolytic enzyme, produced by and stored in the juxtaglomerular apparatus that surrounds each arteriole as it enters a glomerulus. The enzyme affects the blood pressure by catalyzing the change of angiotensinogen to angiotensin, a strong pressor.
Angiotensin I
renin converts angiotensinogen to angiotensinogen I
Angiotensin II
angiotensin I is rapidly hydrolyzed to Angiotensin II which is the active compound. The vasoconstriction action of angiotensin II decreases the glomerular filtration rate, and the concomitant action of aldosterone promotes sodium retention, with the result that blood volume and sodium reabsorption increase.
Aldosterone
a mineral corticoid steroid hormone produced by the adrenal cortex with action in the renal tubule to regulate sodium and potassium balance in the blood
Adrenal Gland
either of two secretory organs perched atop the kidneys and surrounded by the protective fat capsule of the kidneys. Each consists of two parts having independent functions: the cortex and the medulla. The adrenal cortex, in response to adrenocorticotropic hormone secreted by the anterior pituitary, secretes cortisol and androgens. Adrenal androgens serve as precursors that are converted by the liver to testosterone and estrogens. Renin from the kidney controls adrenal cortical production of aldosterone. The adrenal medulla manufactures the catecholamines epinephrine and norepinephrine
Erythropoetin (EPO)
a hormone secreted chiefly by the kidney in the adult and by the liver in the fetus, which acts on stem cells of the bone marrow to stimulate red blood cell production
Calcium-Phosphorus Homeostasis
complex interaction parathyroid hormone (PTH), calcitonin, vitamin D, and three effector organs, the gut, kidney, and bone
Parathyroid Hormone (PTH)
a hormone secreted by the parathyroid glands that acts to maintain a constant concentration of calcium in the extracellular fluid. The hormone regulates absorption of calcium from the GI tract, mobilization of calcium from the bones, deposition of calcium in the bones, and excretion of calcium in the breast milk, feces, sweat, and urine.
Calcitonin
a hormone produced in parafollicular cells of the thyroid that participates in regulating the blood level of calcium and stimulates bone mineralization. Calcitonin acts to reduce the blood level of calcium and to inhibit bone resorption, whereas parathyroid hormone acts to increase blood calcium and bone resorption. The hormone also promotes the excretion of phosphate, sodium, and calcium by decreasing their reabsorption in kidney tubules.
