Endocrine System and Feedback Mechanisms

The most immediate response to a high level of blood sugar in a human is an Increase in the

• muscle activity in the arms

• blood flow to the digestive tract

• activity of all cell organelles 

• release of insulin

The pancreas produces one hormone that lowers blood sugar level and another that increases blood sugar level. The interaction of these two hormones most directly helps humans to

• maintain a balanced internal environment 

• digest needed substances for other body organs. 

• dispose of wastes formed in other body organs 

• increase the rate of cellular communication

Which situation is not an example of the maintenance of a dynamic equilibrium (homeostasis) in an organism?

• Guard cells contribute to the regulation of water content in a geranium plant.

• Water passes into an animal cell causing it to swell. 

• The release of insulin lowers the blood sugar level in a human after eating a big meal.

• A runner perspires while running a race on a hot summer day.

Which statement does not describe an example of a feedback mechanism that maintains homeostasis? 

• The guard cells close the openings in leaves, preventing excess water loss from a plant. 

• White blood cells increase the production of antigens during an allergic reaction.

• Increased physical activity increases heart rate in humans. 

• The pancreas releases insulin, helping humans to keep blood sugar levels stable.

Feedback interactions in the human body are important because they 

• determine the diversity necessary for evolution to occur

• direct the synthesis of altered genes that are passed on to every cell in the body

• regulate the shape of molecules involved in cellular communication 

• keep the internal body environment within its normal range 

Insulin is a molecule, produced by the endocrine system, which regulates sugar concentration in the blood. Most likely, insulin is a

• Sugar

• Hormone

• DNA

• cell

An increase in the level of insulin in the blood would most directly result in

• a decrease in the amount of glucose in the blood

• a decrease in the amount of protein in the blood

• an increase in the amount of fat in cells

• an increase in the amount of carbon dioxide in cells

Which hormone stimulates the release of sugar from the liver into the blood?

• Parathormone

• Insulin

• Glucagon

• FSH

If a person is having difficulty with calcium metabolism, which glands are most likely functioning poorly?

• Gonads

• Parathyroid

• Salivary

• gastric

The hormone adrenaline can affect only cells with

• appropriately shaped receptors

• the appropriate antibodies

• ribosomes that produce adrenaline

• genes that break down adrenaline