bio ch 49

What is osmolarity

The number of osmotically active moles of solute per liter of solution

What does osmotic stress refer to

When the concentration of dissolved substances in cells or tissues is not at the normal set point

What are osmoconformers

An animal that maintains the osmotic concentration of its body fluids at about the same level of the medium it lives in

What is the relation of freshwater vertebrates to their surrounding

They are hypertonic to their environment so water enters their bodies

What is the relation between fish and sea water

Fish are hypotonic to sea water

How does water move in regards to the gills and sea water

Out of the gill epithelium

How does water move in regards to the gills and fresh water

Into the gill epithelium

What are the main ions in extracellular fluid

na and cl

an animal that maintains the osmotic concentration of its body fluids at the same level as its surroundings

osmoconformer

what are the excretory organs in insects that are extensions of the digestive tract

malpighian tubules

what is secreted (pumped) into the Malpighian tubules

waste molecules and potassium ions by active transport

ions or molecules are transported from the body fluid into the tubule by what

secretion

what does the secretion of the potassium ions cause

an osmotic gradient that draws water into the tubules by osmosis

what happens to the water and potassium ions after they enter the tubules

they are reabsorbed into the circulatory system through the hindgut epithelium, leaves only small molecules and waste products to be excreted

what kind of pump do animals and plants use to create an electrochemical gradient

na/k pump for animals and photon pump for plants

how is nitrogenous waste eliminated in humans

urea

is urea water soluble

yes so it can be excreted in large amounts in the urine

what do birds, reptiles, and amphibians do with their nitrogenous waste

convert it to urea

is urea soluble in water

no so it can be excreted using very little water but it takes a lot of energy to form, but it also doesn’t affect embryo

what is the blood like fluid in insects

hemolymph

what does the kidney filter

blood plasma, then it reabsorbs whatever it needs

what filters the blood and where does the filtered blood go after

the glomerulus, leaving cells and large proteins in the blood, rest is filtered to tubule system

the selective movement of solutes out of the filtrate system and back into the blood via peritubular capillaries

reabsorption

the movement of substances from the blood into the extracellular fluid then into the filtrate in the tubular system

secretion

where does filtration occur

the ball of capillaries called the glomerulus

where does the filtrate enter after going through the glomerulus

bowmans capsule, which surrounds the glomerulus

what happens to blood components not filtered out of the glomerulus

empty into the peritubular capillaries

where does the fluid go after bowmans capsule

the loop of henle where important things like water, glucose, and ions are reabsorbed and the rest leaves as urine

how is reabsorption driven in the proximal tubule

na+ is actively pumped out of the filtrate and into the surrounding peritubular capillaries so cl- and water follow

what is the descending tube permeable and impermeable to

permeable to water and impermeable to nacl

what is the ascending tube impermeable to

water

what is pumped out of the ascending tubule

na+ and cl- follows

why does water leave the descending tube

bc all the na and cl left the ascending tube, the surrounding area has a lot of nacl which causes the water to leave

what happens to the nacl pumped out of the ascending limb

its reabsorbed into the vasa recta capillaries (which move countercurrent) so the nacl can diffuse into the blood

what happens when there is low na+ in the blood

aldosterone is release which activates reabsorption of na+

what are the distal tubule and collecting ducts under the control of

hormones to maintain electrolyte balance