Osmoregulation and Kidney

• Osmoregulation

• Osmoregulation: maintaining a balance of salt and water inside the body

• A. osmolarity: total solute concentration of a solution 

  • Osmosis: water will always move from a lower solute concentration to a higher solute concentration 

  • molarity: number of moles of solute in one liter of solution 

  • 1. Isosmotic

  • 2. Hyperosmotic

  • 3. Hyposmotic 

• B. osmoregulatory strategies

  • Osmoregulators

The terrestrial kidney

• A. functions of terrestrials kidney

  • 1. Excretion, nitrogenous wastes

  • 2. Osmoregulation via concentrated or dilute urine 

  • 3. Maintain pH balance- maintain pH system- wide by controlling excretion by hydrogen ions (H+) and reabsorption of bicarbonate ions (HCO3-)

Kidney structures:

• Nephrons: Functional units of the kidney responsible for filtration and reabsorption

• Renal cortex: Outer region of the kidney, containing the glomeruli and part of the nephron

• Renal medulla: Inner region where the loops of Henle and collecting ducts are located, crucial for urine concentration

• Renal pelvis: Funnel-shaped structure that collects urine from the nephron and channels it to the ureter.

• Renal pyramid: Triangular structures located within the renal medulla, playing a key role in the concentration of urine by facilitating the reabsorption of water and solutes.

• Ureters: Tubes that transport urine from the kidneys to the bladder, ensuring proper waste elimination.

• Renal vein: Vessel that carries deoxygenated blood away from the kidneys and back to the heart, completing the circulation of blood through the renal system.

• Renal artery: Vessel that delivers oxygenated blood containing nutrients and waste products to the kidneys for filtration and excretion.

Structure of nephron:

• glomerlus: cluster of capilaries adjacent to Bowmans’s capsule. filtration begins here

• bowman’s capsule: cup shaped part pf nephron surrounding glomerulus. collects filtrate from glomerulus

• proximal tubule: next section of nephron after bowman’s capusule and glomerulus. some substances are reabsorped from filtrate, like HCO3-, NaCl, water, nutrients, potassium

• loop of henle: U-shaped tube in nephron that passes through medulla (renal pyramid). salt is reabsorped from filtrate. water is reabsorped from filtrate.

• distal tbule: more substances are secreted/reabsorbed fro filtrate

• collecting duct: sends filtrate to renal pelvis. concentration of urine happens here. there is higher concentration as you go down the collecting duct

Processes that change the composistion of filtrate:

• filtration: anything small enough to pass through membranes gets forced out of blood and big into Bowman’s capsule

• reabsorption: occurs in the proximal tubule, the distal tubule, loop of Henle. NaCl, glucose, water, H2CO3, and amino acids are reclaimed

• secretion: movement of large molecules that cannot pass through a membrane passivly. large organic waste compundsm, piosons, druges in proximal and distal tubules and loop of henle

• concentration: process tha tchanges concentration of filtrate and produces urine. happens in collecting duct

• filtrate: solution formed from blood being filtered at glomerulus/bowman’s capsule

  • composistion of filtrate can change as it passes through nephron in medulla

  • urine: filtrate taht has passed through the nephron. the compoistion doesn’t change