Chapter 17: Physiology of the Kidneys.

Renal System

Regulates extracellular fluid via urine formation.

Glomerular Filtration

Initial process of filtering blood in kidneys. (glomeruli to capsule)

Reabsorption

Process of reclaiming water and salts from filtrate.

Renal Plasma Clearance

Measure of blood plasma cleared of substances.

Na+/K+ Balance

Regulation of sodium and potassium levels in body.

Acid-Base Balance

Maintenance of pH levels in blood plasma.

Ureters

Tubes transferring urine from kidneys to bladder.

Urinary Bladder

Stores urine until micturition occurs.

Urethra

Tube allowing urine to exit the body.

Renal Cortex

Outer kidney layer for filtration and tubules.

Renal Medulla

Inner kidney layer with loops of Henle.

Detrusor Muscle

Smooth muscle contracting to facilitate urination.

Internal Urethral Sphincter

Smooth muscle controlling urine flow from bladder.

External Urethral Sphincter

Skeletal muscle allowing voluntary control of urination.

Nephron

Functional unit of the kidney with >1,000,000 per kidney.

Gluconeogenesis

Glucose synthesis from amino acids during fasting.

Blood Vessels

Renal artery and vein supply blood to kidneys.

Micturition

Process of urine expulsion from the bladder.

Glomerulus

Capillary network for blood filtration in nephron.

Urine Formation

Process involving filtration, reabsorption, and secretion.

Electrolyte Balance

Regulation of ions like Na+, K+, and HCO3-.

Renal artery

Supplies blood to the kidneys.

Afferent arterioles

Bring blood to glomeruli from renal artery.

Glomeruli

Capillary networks in renal corpuscle.

Glomerular capsule

Surrounds glomerulus; collects filtrate.

Nephron

Functional unit of the kidney.

Filtrate

Fluid filtered from blood in glomerulus.

Efferent arteriole

Carries blood away from glomerulus.

Peritubular capillaries

Surround nephron tubules; facilitate reabsorption.

Renal vein

Drains blood from the kidney.

Proximal convoluted tubule

Site for reabsorption of salt and water.

Loop of Henle

Involved in concentration of urine.

Descending limb

Part of loop; some reabsorption occurs.

Ascending limb

Part of loop; impermeable to water; permeable to Na+, Cl-

Distal convoluted tubule

Further modifies filtrate before collecting duct.

Collecting duct

Drains filtrate into renal pelvis.

Glomerular filtration

Movement of fluid from glomerulus to capsule.

Fenestrae

Large pores in glomerular capillaries for filtration.

Ultrafiltrate

Cell-free fluid similar to plasma.

Reabsorption

Return of filtrate to peritubular capillaries.

Countercurrent Multiplier System

Creates hypertonic interstitial fluid for water reabsorption.

Osmosis

Movement of water from low solute (high water) to high solute (low water) concentration.

Hypertonic

Solution with higher solute concentration than another.

Urine excretion

Only 1-2 L of 180 L filtrate daily.

Countercurrent Multiplier System

Mechanism enhancing urine concentration in kidneys.

Ascending Limb

Part of loop of Henle, Na+ actively pumped.

Descending Limb

Part of loop of Henle, permeable to water.

Osmolarity

Concentration of solutes in a solution.

ISF

Interstitial fluid surrounding nephron structures.

ADH

Hormone regulating water reabsorption in kidneys.

Osmoreceptors

Sensing cells for plasma osmolarity changes.

Renal Plasma Clearance

Volume of plasma cleared of a substance.

Filtration

Process of removing substances from plasma.

Secretion

Movement of substances into tubular fluid.

Reabsorption

Process of returning substances to blood.

Glucosuria

Excretion of glucose in urine, due to excess.

Transport Maximum

Maximum rate of substance reabsorption.

Renin-Angiotensin-Aldosterone System

Hormonal system regulating blood pressure and Na+.

Aldosterone

Hormone stimulating Na+ reabsorption and K+ secretion.

Homeostasis

Maintenance of stable internal conditions.

Acidosis

Condition of increased H+ concentration in blood.

Alkalosis

Condition of decreased H+ concentration in blood.

Bicarbonate Reabsorption

Process of returning bicarbonate to bloodstream.

Urine Volume Regulation

Control of urine output by ADH and aldosterone.

Hypertonic Fluid

Fluid with higher solute concentration than another.

Filtrate

Fluid in nephron before reabsorption and secretion.

Proximal Tubule

Initial segment of nephron for reabsorption.