Week 4 Monday PRQs

A person's blood pressure falls. Which of the answer choices would you expect to occur? Select all that apply.

- Circulating concentrations of renin will increase. - Water uptake by the distal convoluted tubule will increase. When blood pressure falls, - renin will be secreted, which converts angiotensinogen to angiotensin I - lung enzyme converts angiotensin I to angiotensin II - angiotensin II stimulates release of aldosterone, which increase water and salt uptake by distal convoluted tubule - arteries constrict, increasing blood pressure

What function does the low pH of the stomach serve?

- The acidic conditions break down foods directly. - It allows gastric enzymes to work. - It allows for the activation of pepsinogen into pepsin.

Which of the choices is/are secretions produced by the pancreas? Select all that apply.

- bicarbonate ions to neutralize stomach acid - lipase for fat digestion - trypsin for further protein digestion Secretin stimulates the pancreas to secrete bicarbonate ions to neutralize stomach pH. The pancreas secretes lipase and gastric amylase to break down fats and carbohydrates respectively. The pancreas secretes trypsin in an inactive form known as trypsinogen to break down proteins but avoid digesting itself.

An increase of _____ increases the permeability of the collecting duct to water.

ADH (antidiuretic hormone) ADH is released when the body is dehydrated, allowing more water to be reabsorbed from urine.

Which of the statements about the control of blood volume and blood pressure is false?

Angiotensin II stimulates the release of antidiuretic hormone, which increases salt and water uptake by the distal convoluted tubule. Angiotensin II stimulates the release of aldosterone, which increases salt and water uptake by the distal convoluted tubule.

Which of the statements is false?

As food passes through the liver, it is mixed with bile, which breaks large clusters of fats into smaller droplets. Food does not directly pass through the liver. The liver secretes bile into the duodenum.

One of the roles of the kidneys is to help buffer body fluids, to keep fluids from becoming too acidic or too basic. The cells of the renal tubule wall secrete H+ into the tubule lumen and absorb bicarbonate, passing it into the tissue fluid. Consider the reaction catalyzed by the enzyme carbonic anhydrase, shown in the accompanying figure. During heavy exercise, the reaction shifts to the right in the renal tubule cell of the nephron.

False Carbon dioxide from the renal tubule lumen moves into renal tubule cells. Increased amounts of carbon dioxide in the cells shift the reaction to the left.

Which of the statements about the protonephridia of freshwater flatworms is accurate?

Fluid from the body enters the protonephridia without first being filtered. Organisms with protonephridia don't go through filtration before excretion of wastes.

Which of the statements about gastrin is false?

Gastrin secretion is initiated in response to the sight or smell of food. Gastrin is secreted in response to food arriving in the stomach.

What is the function of the vasa recta?

It maintains the concentration gradient established by the loop of Henle. The countercurrent organization of the vasa recta maintains the concentration gradient. Water moves between the two arms of the vasa recta, so there is no net movement of water overall.

The body fluid of sharks has a much lower concentration of sodium chloride than that of the surrounding seawater, and sharks are able to remain in osmotic equilibrium with the external environment. How can this be the case?

Sharks store enough urea to match the total solute concentration of the surrounding seawater. Some osmoconformers like sharks match the seawater's solute concentration by storing a high internal concentration of urea.

If solution X has a 2% concentration of salt (NaCl) and solution Y has an 8% concentration of NaCl, which of the statements is correct?

Solution X is hypotonic relative to solution Y. A hypotonic solution has a higher solute concentration, which would cause water to flow into the solution.

Fish in a marine environment must maintain a relatively constant ion concentration in their tissues and blood. How do the chloride cells in the gills aid fish in the removal of excess ions?

The chloride cells actively remove ions from the body and water follows by osmosis.

Two solutions of water with dissolved potassium and glucose are separated by a selectively permeable membrane that only permits the passage of water. If the two solutions have the same total solute concentration, but solution 1 has a higher concentration of potassium and a lower concentration of glucose than solution 2, which of the statements is correct?

There will be no net movement of water molecules between the solutions. Water moves from low total solute concentration to high total solute concentration.

The digestive tract is well-adapted for digestion and absorption. For most nutrients, once material is in the digestive tract, the digestive system does not vary its rate of absorption according to body needs.

This response is not homeostatic. This response is not monitored by a hormone and is only optimized towards digestion.

During starvation, humans and other animals deplete glycogen and fat reserves first, followed by protein.

True

In the figure shown, digestion in the small intestine is aided by secretions from the liver, gallbladder, and pancreas. Secretin, a hormone produced by cells lining the duodenum, stimulates the pancreas to release bicarbonate ions.

True

Metanephridia differ from protonephridia in that selective reabsorption of materials occurs via cells lining the tubules in protonephridia and via capillaries in metanephridia.

True

Cells can regulate their internal osmotic pressure by controlling the solute concentration inside of the cell.

True Osmoregulation is achieved by the movement of solutes inside and outside of the cell.

In most organisms, the excretion of wastes is closely tied to the maintenance of water and electrolyte balance.

True The wastes excreted have concentrations of solute that can change in response to water and electrolyte levels in the body.

An essential amino acid is defined as one that:

cannot be synthesized by an organism's cellular biochemical pathways.

Salivary amylase starts the chemical digestion of:

carbohydrates in the mouth

Water levels are adjusted to meet the osmoregulatory needs of the organism in the _____ of the nephron under the control of _____, also called vasopressin.

collecting ducts; antidiuretic hormone

An individual with vitamin D deficiency will experience:

difficulty absorbing sufficient amounts of calcium from their diet.

The _____ is the first section of the small intestine, where food enters from the stomach.

duodenum The duodenum finishes any remaining digestion and begins nutrient absorption.

Which of these processes occur within Bowman's capsule?

filtration The Bowman's capsule is responsible for filtering water, wastes, and solutes from the blood as it passes through the capillary wall and capsule into Bowman's space.

Which of the answer choices correctly describes the path taken by excretory fluid through the mammalian kidney?

glomerulus, capsule, renal tubules, collecting ducts, ureter, bladder

Osmoregulators _____ internal solute concentrations compared to their external environment.

have different Osmoregulators regulate osmotic pressure by pumping ions across cell membranes in order to regulate water movement.

Which part of the digestive tract is the predominant location for water and mineral absorption?

hindgut

You discover a new type of marine organism that has the kidneys of a fish but no gills. Based on what you know about other aquatic organisms, the newly discovered organism is _____ compared to the surrounding water.

hypotonic This organism likely produces ammonia as its nitrogenous waste. This requires a lot of water for excretion. Because the fish is hypotonic, it will constantly take on water from its environment. The kidneys are able to produce copious amounts of dilute urine quickly to deal with the constant absorption of water

When an individual has an energy surplus, he or she stores the extra energy as:

lipids

Which process is responsible for creating most of an animal's nitrogenous waste?

protein breakdown during metabolism Protein breakdown is responsible for the production of nitrogenous wastes such as ammonia, urea, and uric acid.

Most mammals excrete _____; most aquatic animals excrete _____; birds, insects, and many reptiles excrete _____.

urea; ammonia; uric acid