BIO 211 & 212: Osmoregulation and Renal Physiology

Comprehensive vocabulary flashcards covering osmoregulation strategies, kidney anatomy, nephron processes, nitrogenous waste forms, and hormonal control based on lecture notes.

Hyposmotic

A state where a solution has fewer solutes than its surroundings, causing water to move OUT.

Isosmotic

A condition where solute concentrations are equal, resulting in no net water movement.

Hyperosmotic

A state where a solution has more solutes than its surroundings, causing water to move IN.

Osmoconformer

An organism whose body fluids match the environment's osmolarity without active regulation, typically having a low energy cost (e.g., marine invertebrates like sea stars and mussels).

Osmoregulator

An organism that actively maintains internal osmolarity regardless of the environment, involving a high energy cost (e.g., most fish, mammals, and birds).

Marine fish (Osmotic Problem)

These organisms lose water and gain salt from their hypertonic environment; they solve this by drinking seawater and pumping salt OUT via gill chloride cells.

Freshwater fish (Osmotic Problem)

These organisms gain water and lose salt in their hypotonic environment; they solve this by not drinking, pumping salt IN via gill chloride cells, and producing dilute urine.

Nasal salt glands

Structures in marine birds and reptiles that actively secrete $NaCl$ to manage excess salt gained from food and seawater.

B.R.E.

A mnemonic for the basics of osmoregulation: Balance water, Regulate electrolytes, and Excrete waste.

Diffusion

The passive movement of substances from a high concentration to a low concentration.

Osmosis

The movement of water toward a higher solute concentration across a semipermeable membrane.

Filtration

A process occurring in the Glomerulus (Bowman's capsule) where blood pressure forces water and small solutes into the filtrate.

Reabsorption

The process where useful substances like glucose, amino acids, ions, and water are moved from the filtrate back into the blood; occurs in the PCT, Loop of Henle, DCT, and collecting duct.

Secretion

The movement of unwanted substances ($H^{+}$, drugs, urea) FROM the blood INTO the filtrate; occurs in the PCT and DCT.

Ammonia ($NH_{3}$)

A very toxic form of nitrogenous waste used by aquatic animals that requires large amounts of water for dilution.

Urea

A moderately toxic nitrogenous waste produced by mammals, sharks, and adult amphibians.

Uric acid

A nitrogenous waste with low toxicity excreted as a paste or solid by birds, reptiles, insects, and snails to conserve water.

Rectal gland

An organ in sharks that uses active transport to pump $NaCl$ out of the body.

Cortex (Kidney)

The outer region of the kidney containing the glomeruli, PCT, and DCT.

Medulla (Kidney)

The inner region of the kidney containing the Loop of Henle and collecting ducts.

Nephron

The microscopic functional unit of the kidney.

ADH (Antidiuretic Hormone)

A hormone released during high blood osmolarity or low blood pressure that acts on the collecting duct to increase water reabsorption via aquaporin channels.

Descending limb (Loop of Henle)

The portion of the nephron permeable to water but not salt, where water flows out to concentrate the filtrate.

Ascending limb (Loop of Henle)

The portion of the nephron permeable to salt but not water, where $Na^{+}$ and $Cl^{-}$ are pumped out to dilute the filtrate.

Vasa recta

Blood vessels that run parallel to the loop of Henle and maintain the medullary gradient as part of the countercurrent multiplier system.

Aldosterone

A hormone released in response to low blood pressure that increases $Na^{+}$ reabsorption in the DCT and collecting duct, causing water to follow.

Renin

An enzyme released during low blood pressure that triggers the RAA pathway by converting angiotensinogen into angiotensin I.

ANP (Atrial Natriuretic Peptide)

A hormone triggered by high blood pressure (stretched atria) that decreases $Na^{+}$ reabsorption in the kidney to reduce blood volume and pressure.

EPO (Erythropoietin)

A hormone released during low $O_{2}$ levels that stimulates the bone marrow to increase red blood cell (RBC) production.

PTH (Parathyroid Hormone)

A hormone released in response to low blood $Ca^{2+}$ that increases $Ca^{2+}$ reabsorption in the kidney and release from bone.