BSC 116 chapter 44
Which of the following statements best describes the actions of the hormone ADH on the nephron?
ADH causes the collecting duct to increase water reabsorption by the surrounding tissue under conditions of dehydration.
Antidiuretic hormone (ADH) and the renin-angiotensin-aldosterone system (RAAS) work together in maintaining osmoregulatory homeostasis through which of the following ways?
ADH regulates the osmolarity of the blood by altering renal reabsorption of water, and the RAAS maintains the osmolarity of the blood by stimulating both Na+ and water reabsorption.
filtration
First step in urine formation; body fluid forced through semi-permeable membrane (water & ions pass through; proteins, etc. do not)
excretion
Forth step in urine formation; remaining filtrate (urine) leaves the body
Ammonia (NH3)
High toxic but highly soluble in water; aquatic organisms can let it diffuse from body surface; terrestrial organisms must retain water
What is the driving force for the filtration of blood by the renal corpuscle?
Higher pressure in glomerular capillaries than in the surrounding Bowman's capsule.
Studies of cricket Malpighian tubules revealed that potassium ions accumulated inside the tubule, moving against the potassium concentration gradient. Based on the information, what can you infer about the mechanism of potassium transport?
Movement of potassium into the lumen of the Malpighian tubules is an energy-requiring process.
Which of the following represents the correct sequence of flow through the nephron?
Renal corpuscle > proximal tubule > loop of Henle > distal tubule > collecting duct
Which regions of the nephron function independently of hormonal control for the most part?
Renal corpuscle, proximal tubule, and loop of Henle.
reabsorption
Second step in urine formation; water and ions selectively taken back
Which of the following statements is true?
The kidneys are paired organs that regulate water and electrolyte balance in terrestrial vertebrates.
secretion
Third step in urine formation; water, etc. acutely added to filtrate
osmoregulation cost energy
actively move solutes so water can follow
Freshwater fish excrete nitrogenous wastes as _____.
ammonia
Protein/nucleic acid metabolism results in the waste product ________
ammonia (NH3)
osmoconformer
an organism who's body fluid is isosmotic with the environment (most marine invertebrates)
osmoregulator
an organism who's body is fluid regulated (freshwater/terrestrial organisms)
In which section of the nephron does the filtrate have a higher osmolarity than the blood when it enters and lower osmolarity than the blood when it leaves?
ascending limb of the loop of Henle
protonephridia of flatworms
beating cilia that draw body fluid into tubes; mostly function for osmoregulation rather than excretion
Antidiuretic hormone (ADH) makes the _____ permeable to water.
collecting duct
The outer part of the kidney is the _____.
cortex
terrestrial tetrapods
dehydration is the main problem for these fish; adaptations in retain water (mostly water-tight), lose water through urine, feces, sweating, evaptoration, and water replaced by drinking/eating
Osmoregulatory adjustment via the atrial natriuretic peptide system can be triggered by ________.
drinking several glasses of water
Regulated changes in the epithelium of the loop of Henle allow the kidney to operate in water-conservation mode
false
The collecting duct concentrates urine by actively reabsorbing NaCl
false
Urine (fluid waste) is produced through 4 steps:
filtration, reabsorption, secretion, excretion
freshwater fish
fish with osmolarity of body fluids greater than freshwater (water gained by osmosis from environment, excretion of water from kidneys, ion uptake from food and across gills)
marine fish
fish with osmolarity of body fluids lower than seawater (water lost by osmosis to environment, must drink lots of sea water, ions excreted from gills and kidneys)
RAAS (renin-angiotensin-adolsterone system)
hormone circuit that matins blood pressure; when blood pressure low, initiates enzyme cascade resulting in vasoconstriction--> increased blood pressure
sea water is ________ relative to our blood
hyperosmotic
freshwater is ______ relative to our blood
hypoosmotic
Which of the following characteristics describes the thin segment of the ascending limb of the loop of Henle?
impermeable to H2O, permeable to NaCl
The body fluids of an osmoconformer would be ________ with its ________ environment
isoosmotic; seawate
Compared to wetland mammals, water conservation in mammals of arid regions is enhanced by having more _____.
juxtamedullary nephrons
In which region of the nephron is a steep osmotic gradient created?
loop of henle
Ammonia is likely to be the primary nitrogenous waste in living conditions that include _____.
lots of fresh water flowing across the gills of a fish
Osmoregulation
maintenance of concentration of solutes in the body
Osmoregulation and excretion are _____.
mechanisms that maintain volume and composition of body fluids
Under the influence of antidiuretic hormone (ADH), _____ is produced.
more concentrated urine
Osmosis
movement of water from low solute (high water) to high solute (low water) concentration across a selectively permeable membrane
What is the basic functional unit of the kidney?
nephron
stenohaline
organisms that can tolerate a narrow range of osmolarities/sallines
euryhaline
organisms that can tolerate substantial changes in external osmolarity
Birds, insects, and many reptiles excrete nitrogenous waste in the form of uric acid, which _____.
reduces water loss compared to other nitrogenous wastes, but requires more metabolic energy to produce
antidiuretic hormone (ADH)
released in response to high blood osmolarity; made in hypothalamus, stored in pituitary; targets distal tubules & collecting ducts: increases water permeability (reabsorption), concentrates urine
The _____ are the major blood vessels transporting blood to the kidneys.
renal arteries
Urine formed by a kidney collects in the _____ before being drained from the kidney by the _____ and transported to the _____.
renal pelvis ... ureter ...urinary bladder
After blood flow is artificially reduced at one kidney, you would expect that kidney to secrete more of the hormone known as _____.
renin
Which of the following is reabsorbed in the proximal tubule, leading to a reduction in the overall filtrate volume?
solutes and water
The force driving simple diffusion is _____, while the energy source for active transport is _____.
the concentration gradient; ATP
Osmolarity
the measure of osmotic pressure (mOsm/L)
A primary reason that the kidneys have one of the highest metabolic rates of all body organs is that _____.
they operate an extensive set of active-transport ion pumps
Which of the following contributes most significantly to the kidney's high energy expenditure?
transport of NaCl in the thick segment of the ascending limb of the loop of Henle
Reabsorption of water and solutes in the proximal tubule reduces the volume of the filtrate.
true
The collecting duct becomes more permeable to water when the kidneys are in water-conservation mode
true
metanephridia of annelids
tube that connects coelom to outside; closely associated with capillaries; functions in both osmoregulation and excretion
Malpighian tubules in insects
tubes connected to gut; solutes (ions, N waste) secreted active transport; epithelium of tubule pumps waste from hemolymph into hindgut; water reabsorbed, nitrogenous wastes end up in feces; conserves water
Many vertebrates convert NH3 (+CO2) to _____; lower toxicity
urea
Reptiles and most terrestrial invertebrates convert NH3 to _____; even lower toxicity
uric acid
Urinary pathway of the mammal
waste fluid leaves each kidney via ureter--> each ureter drains to urinary bladder--> drains to outside via urethra; controlled by sphincter muscles--> kidney composed of outer renal cortex and inner renal medulla; lots of blood vessels & excretory tubules--> each kidney served by renal artery and renal view--> nephrite: functional unit of kidney