Chapter 44: Osmoregulation and Excretion

Which of the following represents the correct sequence of flow through the nephron? (renal corpuscle is the bowmans capsul and glomerolous ) 1.) Renal corpuscle > proximal tubule > loop of Henle > distal tubule > collecting duct 2.)Renal corpuscle > loop of Henle > collecting duct > proximal tubule > distal tubule 3.)Renal corpuscle > distal tubule > proximal tubule > loop of Henle > collecting duct

1 Urine formation in mammals starts with filtration by the renal corpuscle. The volume and composition of the filtrate is modified as it progresses through the proximal tubule, loop of Henle, and distal tubule. Final adjustments to the filtrate take place in the collecting duct.

The transfer of fluid from the glomerulus to Bowman's capsule ________ 1.) is mainly a consequence of blood pressure in the capillaries of the glomerulus 2.) results from active transport 3.) transfers large molecules as easily as small ones

1.) is mainly a consequence of blood pressure in the capillaries of the glomerulus

Which of the following statements best describes the actions of the hormone ADH on the nephron? ADH causes the proximal tubule to increase glucose reabsorption when the body's energy needs are high. ADH causes the collecting duct to increase water reabsorption by the surrounding tissue under conditions of dehydration. ADH causes the loop of Henle to increase urea reabsorption under conditions of dehydration.

ADH causes the collecting duct to increase water reabsorption by the surrounding tissue under conditions of dehydration. ADH increases the water permeability of the distal tubule and collecting duct, increasing the amount of water reabsorbed into the surrounding tissue and decreasing the amount lost as urine.

Which of these is reabsorbed from filtrate? sodium chloride glucose water amino acids

All of these, as well as bicarbonate ions, are reabsorbed from the filtrate.

Trauma to the human kidney could result in a urinary filtrate containing an abnormally high level of a.) glucose b.) fatty acids c.) salts d.) erythrocytes e.) vitamins

Erythrocytes

Which process in the nephron is least selective? -reabsorption -salt pumping by the loop of Henle -active transport -secretion -filtration

Filtration

Like other osmoregulatory animals that live in marine environments, sharks maintain tissue concentrations of sodium, potassium, and chloride that are hypoosmotic to the seawater. In contrast to the bony marine fishes, however, sharks do not need to drink seawater. Why? Sodium, chloride, and potassium do not influence water balance in shark tissues. High urea and trimethylamine oxide concentrations keep shark tissues slightly hyperosmotic relative to seawater, so water is absorbed passively. Sharks excrete large quantities of salt through their gills in exchange for water

High urea and trimethylamine oxide concentrations keep shark tissues slightly hyperosmotic relative to seawater, so water is absorbed passively.

After drinking alcoholic beverages, increased urine excretion is the result of _____.

Inhibited secretion of anti-diuretic hormone (ADH)

Compared to the seawater around them, most marine invertebrates are _____.

Isoosmotic

Under the influence of antidiuretic hormone (ADH), _____ is produced.

More concentrated urine. water is conserved

The movement of substances from the blood into the proximal tubule is known as ____

Secretion; Secretion is the movement of substances from the blood into the kidney tubules.

Glucose is removed from filtrate by _____. secretion diffusion dialysis active transport osmosis

The reabsorption of glucose requires the expenditure of energy. active transport

In which region of the nephron is a steep osmotic gradient created?

The steep osmotic gradient created along the loop of Henle allows water and salts to be returned to the body.

Within a normally functioning kidney, blood can be found in _____.

The vasa recta

A potassium ion gradient is set up in insect Malpighian tubules through an active transport process. As a result, potassium concentration is higher in the lumen of the tubules than in hemolymph. How would the potassium gradient affect water movement?

There would be a net movement of water into the lumen of the tubules.

Single-celled Paramecium live in pond water (a hypotonic environment). They have a structural feature, a contractile vacuole, which enables them to osmoregulate. If you observed them in the following solutions, at which sucrose concentration (in millimolars, mM) would you expect the contractile vacuole to be most active? a.) 0.0 mM sucrose b.) 0.05 mM saline c.) 0.08 mM sucrose d.) 1.0 mM saline

a.) 0.0 mM sucrose

Antidiuretic hormone (ADH) makes the _____ permeable to water.

collecting duct; this results in the reabsorbtion of water.

Low selectivity of solute movement is a characteristic of _____.

filtration from the glomerular capillaries

The movement of substances out of the glomerulus and into Bowman's capsule is referred to as _____. secretion reabsorption active transportion pumping filtration

filtration; Blood pressure is the force behind the filtration of substances out of the glomerulus and into Bowman's capsule.

In humans, the transport epithelial cells in the ascending loop of Henle _____.

have plasma membranes of low permeability to water

What is the driving force for the filtration of blood by the renal corpuscle?

higher pressure in glomerular capillaries than in the surrounding bowmans capsul. The blood pressure in the glomerular capillaries is higher than in the Bowman's capsule, so water and small solutes are forced out of the blood through capillary pores, leaving the larger components of the blood behind.

The body fluids of an osmoconformer would be ________ with its ________ environment. -hyperosmotic; saltwater -isotonic; freshwater -hypoosmotic; saltwater -isoosmotic; saltwater

isoosmotic; saltwater

A necropsy (postmortem analysis) of a marine sea star that died after it was mistakenly placed in fresh water would likely show that it died because..

it was so hyperosmotic to the fresh water that it could not osmoregulate

Among the following choices, the most concentrated urine is excreted by _____. kangaroo rats frogs freshwater bass humans sea birds

kangaroo rats

As filtrate moves down the loop of Henle, the surrounding interstitial fluid becomes _____ concentrated than the filtrate, so _____ leaves the filtrate. more ... urea less ... urea more ... water less ... water less ... water and urea

more.. water; The increasing solute concentration of the interstitial fluid results in water leaving the filtrate by osmosis.

Materials are returned to the blood from the filtrate by which of the following processes? a.) filtration b.) excretion c.) secretion

none of these! Reabsorbtion is the process by which materials are returned to the blood from the filtrate lol

In animals, nitrogenous wastes are produced mostly from the catabolism of..

proteins and nucleic acids

Birds secrete uric acid as their nitrogenous waste because uric acid...

requires little water for nitrogenous waste disposal which will reduce body mass.

The force driving simple diffusion is _____, while the energy source for active transport is _____

the concentration gradient; ATP

The most abundant solute in urine is _____. glucose water plasma proteins sodium chloride urea (and other nitrogenous wastes)

urea and other nitrogenous wastes; Nitrogenous wastes, such as urea, are the primary solute found in urine.

The advantage of excreting nitrogenous wastes as urea rather than as ammonia is that ________. -urea is less toxic than ammonia -less nitrogen is removed from the body -urea does not affect the osmotic gradient -urea can be removed as a semi-solid paste

urea is less toxic than ammonia

A human who has no access to fresh water but is forced to drink seawater instead will ________. 1.) passively excrete excess water in order to remove the high concentration of ingested salt 2.) risk becoming overhydrated within twelve hours 3.) produce excessive antidiuretic hormone to remove more water but hold back salts 4.) release atrial natriuretic peptide to decrease blood pressure

1.) passively excrete excess water in order to remove the high concentration of ingested salt

Tissues of sharks are isotonic to seawater, but their concentrations of sodium ions, potassium ions, and chloride ions in cells and extracellular fluids are similar to those of freshwater fishes. What can you infer about the movement of sodium and chloride in these animals?

Sodium and chloride will diffuse into shark gills from seawater down their concentration gradient.

Natural selection should favor the highest proportion of juxtamedullary nephrons in which of the following species? a.) a river otter b.) a mouse in a tropical rain forest c.) a mouse living in a desert d.) a mouse living in a temperate braodleaf forest

c.) a mouse living in a desert.

Ammonia ____. a.)is metabolically more expensive to synthesize than urea b.)has low toxicity relative to urea c.) Is soluble in water d.) is the major nitrogenous waste excreted by birds?

c.) is soluble in water

Increased antidiuretic hormone (ADH) secretion is likely after _____. a.) blood pressure becomes abnormally high b.) drinking lots of pure water c.) sweating-induced dehydration increases plasma osmolarity d.) eating a small sugary snack

c.) sweating induced dehydration increases plasma osmolarity.

The loop of Henle dips into the renal cortex. This is an important feature of osmoregulation in terrestrial vertebrates because _____. Either... a.) absorptive processes taking place in the loop of Henle are hormonally regulated or b.) additional filtration takes place along the loop of Henle and the loop of henle plays important role in detoxification or c.) differential permeabilities of ascending and descending limbs of the loop of Henle are important in establishing an osmotic gradient

c.)differential permeabilities of ascending and descending limbs of the loop of Henle are important in establishing an osmotic gradient