osmoregulation and excretion

Osmoregulation

The process by which organisms maintain the balance of water and solutes in their bodies.

Aquaporins

Proteins essential for the transport of water and solutes across membranes.

Tonicity

The ability of a solution to affect cell volume through osmosis.

Concentration gradient

The primary driving force for the movement of substances across plasma membranes.

Osmosis

The movement of water across a semi-permeable membrane.

Osmolarity

The measure of osmotically active moles of solute per liter of solution.

Hyperosmotic

A solution with a higher solute concentration.

Hypoosmotic

A solution with a lower solute concentration.

Isoosmotic

Solutions with equal solute concentrations, leading to equal rates of movement across a membrane.

Tonicity vs. Osmolarity

Tonicity measures the effect of a solution on cell volume, while osmolarity quantifies the solute concentration.

Hypertonic Solution

A solution that causes water to leave the cell, decreasing its size.

Hypotonic Solution

A solution that causes water to enter the cell, increasing its size and potentially leading to lysis.

Isotonic Solution

A solution where the movement of water into and out of the cell is equal, maintaining cell volume.

Osmoconformers

Organisms that maintain an internal osmolarity equal to their external environment.

Osmoregulators

Organisms that actively regulate their internal osmolarity, differing from their environment.

Sharks (Osmoregulation)

Sharks retain high concentrations of urea in their blood to achieve an isoosmotic state with seawater.

Water Movement

Water moves from areas of higher free water concentration to higher solute concentration.

Anhydrobiosis

A survival strategy allowing organisms to endure extreme water loss by entering a dehydrated dormant state.

Freshwater Fish Adaptation

Do not drink water, actively transport ions into their bodies, and excrete large volumes of dilute urine.

Marine Fish Adaptation

Drink seawater, actively excrete excess ions through gills, and produce scanty urine.

Urea

A less toxic nitrogenous waste produced by mammals, requiring moderate energy expenditure for synthesis.

Ammonia

The most toxic nitrogenous waste excreted by many aquatic animals, requiring large amounts of water for disposal.

Uric Acid

A nitrogenous waste excreted by birds and reptiles; it's water-insoluble and conserves water.

Protonephridia

Simple filtration systems in flatworms using tubules for excretion.

Metanephridia

Excretory structures in earthworms that filter fluid from the body cavity.

Malpighian Tubules

Excretory structures in insects that collect waste from hemolymph and lead to excretion with feces.

Glomerulus

A cluster of fenestrated capillaries involved in the filtration of blood in the kidney.

Bowman’s Capsule

A cup-like structure surrounding the glomerulus where filtrate collects.

Glomerular Filtration Rate (GFR)

The volume of filtrate produced by the kidneys per unit of time.

Net Filtration Pressure (NFP)

The pressure that determines the rate of filtration, calculated as GBHP - CHP - BCOP.

ADH (Antidiuretic Hormone)

A hormone that increases water reabsorption in the kidneys by enhancing aquaporin activity.

RAAS (Renin-Angiotensin-Aldosterone System)

A hormonal system regulating blood pressure and fluid balance, activated by low blood volume or pressure.

Aldosterone

A hormone that promotes sodium reabsorption in the kidneys, increasing blood volume.

Atrial Natriuretic Peptide (ANP)

A hormone that inhibits sodium reabsorption, promoting water excretion and lowering blood volume.

Countercurrent Multiplier System

A mechanism in the nephron loop that establishes a high osmotic gradient for urine concentration.

Countercurrent Exchange

A process preserving the osmotic gradient in the kidney, involving blood flow in the vasa recta.

Urea Recycling

The process by which urea re-enters the nephron loop to assist in establishing osmotic gradients.

Filtrate Composition

Initially consists of salts, glucose, amino acids, vitamins, and waste products.

Peritubular Capillaries

Capillaries surrounding the renal tubules involved in reabsorption and secretion.

Efferent Arteriole

Carries blood away from the glomerulus following filtration.

Afferent Arteriole

Carries blood towards the glomerulus for filtration.

Kidney Functions

Includes regulation of water volume, solute concentration, and filtration to form urine.

Mammalian Urinary System

The system including kidneys, ureters, bladder, and urethra for urine production and excretion.

Kidney Anatomy

Includes renal cortex, renal medulla, and renal pelvis, each contributing to urine formation.

Cortical Nephrons

Nephrons primarily located in the renal cortex and involved in regular filtration functions.

Juxtamedullary Nephrons

Nephrons with long loops that enhance the kidney's ability to concentrate urine.

Distal Tubule (DCT)

The nephron segment that fine-tunes reabsorption and secretion before urine formation.

Collecting Duct

Structure that receives filtrate from nephrons and is involved in hormone-regulated reabsorption.