Chapter 48: Regulating the Internal Environment Flashcards
What is osmoregulation?
regulation of water and ion balance
What makes up the ECF?
ISF and blood plasma
What is osmolarity?
The total solute concentration of a solution
What is the osmolarity of body fluids in humans and other mammals?
about 300 mOsm/L
What occurs at the proximal vs distal end of excretory tubules?
proximal where fluid goes in and distal end is where fluid flows to the exterior of the organism
What are the 4 steps in tublue function?
filtration, tubular reabsorption, tubular secretion, and excretion
Key points about ammonia?
NH3, 1N
soluble in water, highly toxic
must be excreted in dilute solutions—high water loss
fishes
Key points about urea?
2N
all mammals, most amphibians, some reptiles, some marine fishes, and some terrestrial invertebrates
nontoxic
minimal water needed
Key points about uric acid?
4N birds and reptiles nontoxic paste extremely low water loss
What common osmoconformers? typically osmolarity?
marine invertebrates, about 1000 mOsm/L
What common osmoregulators?
all freshwater invertebrates
What are the 3 types of tubules and where are they found?
Protonephridia- flatworms and larval mollusks
METANEPHRIDIA- ANNELIDS AND MOST ADULT MOLLUSKS
MALPIGHIAN TUBULES- INSECTS AND OTHER ARTHROPODS
What is a flame cell? located?
located in protonephridia, contain cilia that move fluid through the tubule
What are peritubular capillaries?
reabsorb important molecules and ions from the filtrate
Is the collecting duct part of the nephron?
nope
What are the 4 major regions of the nephron?
renal corpuscle, proximal convoluted tubule, loop of henle, and distal convoluted tubule
Which has a bigger diameter the afferent arteriole or efferent arteriole? purpose?
afferent arteriole to maintain a high level of glomerular capillary pressure
What is the structure of the Bowman’s capsule and glomerulus?
glomerulus is a ball of arterial capillaries, Bowman’s capsule houses the glomerulus and is where filtration occurs
What happens in the proximal convoluted tube?
bicarb, NaCL, H2), nutrients, K pumped out for reabsorption
H+ and NH3 pumped in for excretion
What happens in the descending loop of henle?
H2O moves out and NaCl moves in. osmolarity increases
What is the purpose of the distal tubule?
allows for more water reabsorption, allows for adaption to the environment
Are the collecting ducts permeable to water? salt?
yes to water, no to salt ions
What is the difference between the macula densa and juxtaglomerular cells? what do these two form?
macula densa focus on what is leaving
juxtaglomerular cells focus on what is entering
form juxtaglomerular complex
What is the raas regulatory mechanism?
renin-angiotensin-aldosterone system
regulates Na, fixes levels if juxtaglomerular complex fails to do so
How do ACE inhibitors work?
prevents the secretion of angiotensin II which lowers blood pressure. Prevents the secretion of aldosterone from the adrenal glands which would increase blood volume
What are the 3 effects of angiotensin II?
1) raises bp via constricting arterioles
2) stimulates synthesis/secretion of aldosterone
3) stimulates thirst
What are the 3 effects of atrial natriuretic factor (ANF)?
1) inhibits renin release
2) dilates afferent arterioles
3) inhibits aldosterone release
Where are ADH-secreting neurons located?
hypothalamus
What does ADH do?
increases water reabsorption in collecting ducts by promoting the insertion of more aquaporins into the epithelial membranes
doesn’t work in distal convoluted tubules
What are marine teleosts?
fishies that continually lose water to their environment by osmosis and must replace it by continual drinking
they try and dilute the ocean
don’t pee a lot of water out
How do sharks and rays maintain osmolarity as conformers?
retaining high levels of urea and trimethylamine oxide (TMAO) in body fluids
they don’t have to drink water
What occurs in freshwater fish?
they are hyperosmotic to their environment, so the water moves into the fish—don’t have to drink water
pee a lot of water out
In terrestrial amphibians what is the function of the bladder?
in addition to storage of urine, reabsorption of salt occurs also
How do birds and reptiles deal with salt/water concentrations?
they have salt glands that take on excess salt which are excreted in a concentrated salt solution
How do terrestrial mammals conserve water? (3)
1) loop of henle
2) lungs deep in body to reduce evaporation
3) covered in keratinizes skin to reduce evaporation
What are the 4 ways to lose or gain heat?
conduction, convection, radiation, and evaporation
Difference between conduction and convection?
convection is indirect contact, conduction is direction contact
What is an ectotherms?
cold-blooded animals that don’t produce their own heat source. move around their environment to obtain heat
What is an endotherms?
warm blooded, have set points
How does cold weather effect ectotherms and endotherms differently?
ectotherms metabolism doesn’t change much but daily activities are reduced
endotherms metabolic rate rise at low temps and maintain daily activities
How can some ectotherms react to cold temps?
add an “antifreeze” molecule like glycerol to their body fluids
What does the core temperature refer to?
abdominal and thoracic organs, CNS, and skeletal muscles
Where are thermoreceptors found?
skin (integument), spinal cord, and hypothalamus
What is the purpose of brown adipose tissue?
can produce heat rapidly
How do animals without sweat glands sweat?
via panting
What are keratin fibers?
a surface layer of dead epidermal cells that forms a tough layer resistant to water loss
What does the dermis contain?
sweat glands, hair follicles, and thermoreceptors
What does the hypodermis contain?
larger blood vessels and fatty tissue/blubber
What is torpor?
reduction in metabolic, nervous, and physical activity induce this sleep like state—-falling iguanas
hibernation- extend torpor
What is estivation?
too hot/water scares–ex) burying in mud to cool down
How does countercurrent head exchange occur in the blood?
warm blood from artery warms blood in vein returning to the heart via conduction
How does countercurrent head exchange occur in the nose?
when exhaling some water condense on the nasal fold. inhalation air evaporates some air on nasal fold which cools the folds for the next outgoing breath.
