bio 11: Excretion and Osmoregulation

Excretory system

- maintenance of the volume and composition of extracellular fluid - removes metabolic wastes from the bloodstream

Osmoregulation

- maintenance of proper internal salt and water concentrations in a cell or in the body of a living organism - active regulation of internal osmotic pressure

shore crab

- euryhaline - osmotic regulator • hyperosmotic

spider crab

- stenohaline - osmotic conformer

osmotic regulator

is an organism that actively controls its internal osmotic pressure, meaning it maintains a relatively constant internal solute concentration despite changes in the surrounding environment.

osmotic conformer

is an organism whose internal osmotic pressure (the force required to prevent osmosis, or the movement of water across a membrane) is equal to the osmotic pressure of its external environment. In simpler terms, they have the same salinity as the surrounding water.

euryhaline

able to live in waters of a wide range of salinity

stenohaline

able to tolerate only a narrow range of salinity.

hypoosmotic regulator

actively absorbs, NaCl, produce large volumes of dilute urine, active reabsorbtion of NaCl in the kidneys to conserve salts, large glomerulus

hyperosmotic regulator

actively secrete salts (NaCl) and minimize water loss, produce small amounts of concentrated urine to conserve water, active tubular secretion of MgSO4, glomerulus is reduced or absent,

Protozoan contractile vacuoles

• tiny, spherical, intracellular vacuole found in protozoa • expels excess water gained by osmosis

1. canals take up water from the cytoplasm

2. water moves from canals to vacuole

3. vacuole fills with water

4. pore opens and vacuole contracts

5. contraction of vacuole expels water

6. empty vacuole

step by step process of contractile vacuoles work in protozoans

Protonephridia

• branching network of dead-end tubules • found in flatworms, rotifers, some annelids, larval mollusks, and lancelets • closed system

Metanephridia

• Found in annelids, molluscs, and other phyla • Made of tubules that are open at both ends • Surrounded by a network of blood vessels that assists in reclamation of water and valuable materials such as salts, sugars and amino acids

coxal glands, antennal gland

execretory glands of arthropods

Malpighian tubules

are excretory and osmoregulatory structures found in insects and some arachnids (like spiders and scorpions). They serve a similar role to kidneys in vertebrates.

1. Waste and ions enter the tubules from the blood (hemolymph) 2. Tubular fluid enters the midgut/hindgut 3. Reabsorption in the hindgut 4. Concentration of waste 5. Elimination

process of how malphigian tubules in insects works

nasal glands

execretory glands of marine birds

Anhydrobiosis

adaptations of a tardigrades/water bears in terms of execretory

Anhydrobiosis

a biological state where an organism survives extreme dehydration by virtually halting its metabolism until water becomes available again.

decreased water urine

adaptations of kangaroo rats in execretory

proteins and nucleic acids

where nitrogen is sourced in nitrogenous wastes

ammonia

nitrogenous wastes of most aquatic animals

urea

nitrogenous wastes of most mammals, amphibians, shark, some bony fishes

uric acid

nitrogenous wastes of birds, insects, many reptiles, land snails

archinephros

kidney found in embryo of hagfish; this is the inferred ancestral condition of the vertebrate kidney

pronephros

functional kidney in adult hagfish and embryonic fishes and amphibians; fleeting existence in embryonic reptiles, birds, and mammals

mesonephros

functional kidney of adult lampreys, fishes, and amphibians; transient function in embryonic reptiles, birds, and mammals

metanephros

functional kidney of adult reptiles, birds, and mammals

Nephrons

are the microscopic structural and functional units of the kidney responsible for filtering blood, reabsorbing nutrients, and excreting waste as urine.

Renal Corpuscle

filtration unit of kidney

Renal Tubule

reabsorption/secretion unit of kidney

Filtration, Reabsorption, Secretion, Urine Formation

function of nephrons

Glomerular Filtration

water, salts, nutrient molecules, and waste molecules move from the glomerulus to the inside of the glomerular capsule. these small molecules are called the glomerular filtrate

Tubular Reabsorption

Nutrient and salt molecules are actively reabsorbe from the convoluted tubules into the peritubular capillary network, and water flows passively

Tubular Secretion

Certain molecules (eg. H plus and penicillin) are actively secreted from the peritubular capillary network into the convoluted tubules

1. proximal tubule 2. descending limb of loop of henle 3. thin segment of ascending limb 4. thick segment of ascending limb 4. distal tubule 5. collecting duct

urine formation in nephrons

1. kidneys produce urine 2. ureters transport urine 3. urinary bladder stores urine 4. urethra passes urine to outside

urine pathways in humans

Antidiuretic hormone (ADH)

also called vasopressin, is a hormone produced in the hypothalamus and released by the pituitary gland. Its primary role is to regulate water balance in the body by controlling how much water the kidneys reabsorb.

Antidiuretic hormone (ADH), renin-angiotensin-aldosterone system

increases blood pressure

(RAAS)

increases blood pressure

atrial natriuretic factor (ANF)

• opposes the RAAS • released by the walls of the atria in response to an increase in blood volume and pressure • inhibits the release of renin from the JGA • inhibits NaCl reabsorption by the collecting ducts • reduces aldosterone release from the adrenal glands • these actions lower blood pressure and volume

atrial natriuretic factor (ANF)

lowers blood pressure