EXAM 4 Flashcards
Hyperosmotic solution
- solution has more solute
- cell has less solute
- water flows out of cell
- cell shrinks, dries out, dies
hyposmotic solution
- solution has less solute
- water flows into cell
- cell expands, explodes, lyses
The main contributors of osmolarity in blood and sea water are ____ & ____
sodium and chloride
In marine (saltwater) environments, animals tend to ___ salts and ___ water
gain salts, lose water
in freshwater environments, animals tend to ___ salts and ___ water
lose salts, gain water
because many animals move between environment they must be able to ___
alter their homeostatic mechanisms
Two strategies to meet osmotic challenges are ______
- Osmoconformer
- Osmoregulator
characteristics of an osmoconformer
- internal and external osmolarity are similar
- e.g.: marine invertebrates (clam)
two types of osmoconformers
- ionoconformer
- ionoregulator
ionoconformer
same ions and same osomolarity
ionoregulator
different ions but same osmolarity
characteristics of an osmoregulator
- osmolarity constant regardless of external environment
- most vertebrates
stenohaline
- can tolerate a narrow range of external ion levels
euryhaline
- can tolerate a wide range of external ion levels
three groups of solutes
- perturbing solute
- compatible solute
- counteracting solutes
perturbing solute
- damages enzyme activity
- lowers enzyme binding affinity
- increases Km
compatible solute
- increase does not really effect enzyme activity or Km
counteracting solutes
- Two solutes that balance each other’s activity out
Seawater fish…
- hyperosmolar environment
- lose water through osmosis through gills and other parts of body surface
- drink water
- gills to remove NaCl
- urine - small volume
- bony fish use gills to remove sodium chloride
- expel ions in feces as well
- Excretion of salt ions and small amounts of water in urine
Freshwater fish…
- generate large amounts of diluted urine
- lose ions
- don’t drink more water
- gills - uptake NaCl
- urine - large volume, highly diluted
- uptake of water and some ions in food
Apical Membrane faces____
faces environment
basolateral membrane faces___
faces internals
four features of transport epithelia
- asymmetrical distribution of membrane transporters
- cells interconnected, impermeable, little leaking
- high cell diversity
- abundant mitochondria
transcellular transport:
transport in, cross cell, leave other side
paracellular transport:
some transport that occurs in the tight junctions between cells
aquaporins allow ____ molecules per minute to pass
1 billion
Fish gill lamellae are composed of
- mitochondria-rich chloride cells
- pavement cells (m. rich)
- pavement cells (m. poor)
fish that migrate between saltwater and freshwater
diadromous
____ functions change during migration of fish between environments
ion transport
ion transport changes in fish are controlled by____
hormones
land animals can reduce water with layers of ____
hydrophobic molecules
Three types of hydrophobic coatings on land animals
- mucus
- cornified stratum corneum with keratin (e.g.: amniotes)
- cuticle with chitin (e.g.: arthropods)
Three sources of water - land animals
- dietary water
- metabolic water (oxidative phosphorylation)
- drinking
mL water gain (rat)
- food (0.2mL)
- metabolism (1.8mL)
mL water loss (rat)
- feces (0.09mL)
- urine (0.45mL)
- evaporation (1.46mL)
mL water gain (human)
- food (750mL)
- liquid (1500mL)
- metabolism (250mL)
mL water loss (human)
- feces (100mL)
- urine (1500mL)
- Evaporation (900mL)
3 kinds of nitrogen excretion
- ammonium
- uric acid
- urea
3 categories of animals based on nitrogen excretion method
- ammonioteles (ammonium) [invertebrates, molluscs, aq)
- uricoteles (uric acid) [arthropods, reptiles, birds]
- ureoteles (urea) [all mammals, some bony fish]
ammonia excretion advantages
- deamination of amino acids
- requires little energy (1 ATP)
ammonia excretion disadvantages
- highly toxic
- requires large volumes of water to store and excrete
uric acid excretion advantages
- few toxic effects
- can be excreted in small volume of water
uric acid excretion disadvantages
- energetically expensive (7 ATP)
urea excretion advantages
- only slightly toxic
- relatively inexpensive to produce
urea excretion disadvantages
- perturbing solute
6 roles of vertebrate kidneys in homeostasis
- ion balance
- osmotic balance
- blood pressure
- pH balance
- excretion of metabolic wastes and toxins
- hormone production
nephron is composed of
- renal tubule
- vasculature (system of blood vessels)
4 processes of urine production
- filtration (at glomerulus)
- reabsorption (specific molecules in filtrate removed)
- secretion (specific molecules added to the filtrate)
- excretion (urine excreted from body)
kidney filtration
- liquid components of blood filtered into bowman’s capsule
- water and small solutes cross glomerular wall
- blood cells and large macromolecules are not filtered
glomerular capillaries are very _____
leaky
___ with ____ form filtration structure
podocytes with foot processes
_________ control blood pressure and filtration within glomerulus
mesangial cells
filtrate flows from Bowman’s capsule into ______
proximal tubule
primary urine
initial filtrate filtered in bowman’s capsule (is isosomotic to blood)
most ___ and ___ in primary urine is reabsorbed using ___ and ____
water, salt
transport proteins, energy
renal threshold
concentration of a specific solute that will overwhelm reabsorptive capacity
rate of reabsorption is limited by _______
number of transporters
each zone of the nephron has ________ for ____ solutes
transporters for specific solutes
kidney secretion
- reverse of reabsorption
- molecules are removed from blood and transported into filtrate
secreted molecules in the kidney
K+, NH4+, H+, pharmaceuticals, water-soluble vitamins
secretion requires _______ and ______
transport proteins, energy
Tubule regions of the kidney
- proximal tubule
- loop of henle
- distal tuble
- collecting duct
proximal tubule
- most of solute and water reabsorption
loop of henle
- descending limb
- ascending limb
distal tubule
- reabsorption completed for most solutes
collecting duct
- drains multiple nephrons
- carries urine to renal pelvis
Descending limb is permeable to ____
H2O
Descending limb…
- water is reabsorbed
- volume of primary urine decreases
- primary urine becomes more concentrated
Ascending limb is impermeable to ____
H2O
Ascending limb…
- ions are reabsorbed
- primary urine becomes dilute
reabsorbed ions accumulate in the _______
interstitial fluid (creates osmotic gradient in the medulla)
blood vs. filtrate in loop of henle runs ______
countercurrent
Distal tubule can reabsorb ____ and ____
salts and water
distal tubule can secrete _______
potassium
Transport function in distal tubule controlled by _____
hormones
____________ increases Ca2+ reabsorption
parathormone
____________ increases K+ secretion
aldosterone
after urine is produced, it leaves____ and enters _____ via _____
kidney, urinary bladder, ureters
urine leaves bladder via ______
urethra
opening and closing of urethra sphincters controlled by _________
spinal cord reflex arc (micturition reflex) (can be influenced by voluntary controls)