Excretory System Flashcards
What are the functions of the excretory system?
- maintain proper internal levels inorganic solutes
- maintain proper plasma and water volume
- removal of waste
- maintain osmotic balance
What are the functions of the excretory system?
- maintain proper internal levels inorganic solutes
- maintain proper plasma and water volume
- removal of waste
- maintain osmotic balance
What are nitrogenous wastes the result of?
metabolism of proteins and nucleic acids
What does the choice of primary nitrogenous waste correlate with?
water availability
Name and describe the nitrogenous waste from most toxic to least.
- Ammonia: MOST toxic; expelled by most aquatic animals that breathe water (ammonotely); can’t be broken down so it gets diluted to a non-toxic concentration.
- Urea: expelled by most terrestrial animals (humans included) [ureotely], more expensive metabolically but is less toxic than ammonia.
- Uric Acid: expelled by insects, reptiles, & birds (uricotely); most expensive metabolically, highly insoluble, highly non-toxic; makes water conservation for animals (semi-solid form).
Explain the process of transport epithelia.
There is a Na+/K+ ATPase pump on the basolateral (top) side of the membrane, making the Na+ concentration inside the cell lower (because pumps Na+ out of cell and K+ into). Na+ then enters the apical (bottom) side by diffusing through ENaC (epithethial Na channel). Cl- wants to counteract the outside charge (attracted to Na+), so it goes through CIC or CFTR channels and changes the gradient produced by the Na+ efflux. This increases the extracellular solute concentration, which attracts water (osmosis, low solute concentration to high to dilute) across basolateral membrane. This occurs on the PCT.
What is filtration?
water and small solutes can pass through a barrier, while cells and larger molecules remain behind (comes from the blood and goes into another area)
What is secretion?
transport epithelia move specific solutes into tubule for lumen secretion
What is reabsorption?
transport epithelia move specific solutes and water back into the body from the lumen
What is osmoconcentration?
water is removed from lumen, laving solutes behind, producing more concentrated excretory fluid (hyper osmotic)–> goal to concentrate urine and reabsorb water to avoid dehydration
What are the parts of the excretory system?
- kidneys: urine forming organ, have 2 one on each side of vertebral column (houses renal pelvis where kidney stones develop)
- ureters: tube like things that urine drains into from the kidneys (have 2)
- urinary bladder (or hindgut in reptiles and birds) ureters empty urine here
- urethra: bladder empties urine into and urine goes out through
What are the regions of the kidney?
- renal cortex (outer portion)
- renal medulla (inner- divided into renal pyramids in larger mammals)
- renal pelvis (drainage area in the center of the kidneys, collects urine and releases it–where kidney stones occur)
What is a nephron and how many are in the human body?
smallest functional unit of the kidney we have ~1 million
afferent arteriole
supplies each nephron by bringing dirty blood in, made of smooth muscle
glomerulus
ball-like knot of capillaries in renal cortex, site of filtration of blood, its twisted to increase SA
efferent arteriole
exits the glomerulus and carries semi-clean blood
pertitubular capillaries
surrounds tubules, puppies renal tissue with blood and exchanges materials with tubular fluid
Bowman’s (glomerular) capsule
site of glomerular filtration
proximal (convoluted) tubule
PCT, involved in tubular reabsorption and secretion
loop of Henle
part of osmoconcentration, descending limb (plunges into medulla), ascending limb (returns to the cortex)
distal (convoluted) tubule
DCT, involved in reabsorption/secretion and osmoconcentration
collecting duct
involved in osmoconcentration, empties into renal pelvis
juxtaglomerular apparatus
JGA, sensor in osmoregulation and blood pressure regulation, on DCT near glomerulus, wants to dictate what the afferent arteriole does
Describe elasmobranch urinary systems.
- isosmotic or hyper osmotic relative to seawater
- fish itself is hyper osmotic, lots of solute–water wants to go into, blocks Na+
- retain urea and trimethylamine oxide (TMAO)–breaks down, gives off fishy smell, uses compound to bring water in
- hindgut excretes hypertonic fluid high in salt