BIO 202 Exam 1 Questions with 100% Correct Answers

Discuss the way in which hormones promote body homeostasis. Correct Answer Get stimulated when homeostasis is thrown off Compare and contrast the endocrine system and the nervous system. Make sure you understand the differences between a neurotransmitter and a hormone, addressing the importance of receptor specificity. Correct Answer Endocrine - Uses hormones released by endocrine glands Effects many effector organs (i.e. HGH to all muscles) Is slower and longer lasting Nervous - Uses electricity and chemicals to send a fast message Has a specific effector organ (i.e. certain muscle) Uses neurotransmitters released by neurons Define negative feedback and describe its role in regulating blood levels of the various hormones. Use an example if you like! ☺ Correct Answer Response to changed body condition if body is high or low from normal level signal tells body to make changes that will bring body back to normal level once body is back to normal level, signal is turned off List AND describe the four types of intercellular communication pathways that enable the body to maintain homeostasis. Correct Answer - Direct communication -- Exchange of ions and molecules between adjacent cells across gap junctions -- Occurs between two cells of same type -- Where have we seen these before? -- Cardiac muscle cells - Paracrine communication -- Uses chemical signals to transfer information from cell to cell within single tissue -- Most common form of intercellular communication -- i.e. Certain growth factors -Endocrine communication -- Endocrine cells release chemicals (hormones) into bloodstream -- Alters metabolic activities of many tissues and organs simultaneously -- Analogy once again: Bulk mail - in Russian -Synaptic communication Define hormone and target organ. Correct Answer Hormone - Stimulate synthesis of enzymes or structural proteins Increase or decrease rate of synthesis Turn existing enzyme or membrane channel "on" or "off" Target organ - Are specific cells that possess receptors needed to bind and "read" hormonal messages What does the "lock and key system refer to? Explain! Correct Answer hormone fits receptor on "target" cell What are the three ways in which hormones are classified? Yes, you will have to which type of chemical structure each hormone that we study falls under. For example, you will need to know that catecholamines are amino acid derivatives. Correct Answer Amino acid derivatives -Where have we seen amino acids before? Peptide hormones Lipid derivatives Steroids Corticosteroids/ anabolic steroids All of these either circulate freely in the blood or are bound to transport proteins Compare and contrast the functionality of free vs. protein bound hormones in the plasma (bloodstream). Correct Answer - Free Hormones Remain functional for less than 1 hour Diffuse out of bloodstream: bind to receptors on target cells Are broken down and absorbed by cells of liver or kidney Are broken down by enzymes in plasma or interstitial fluids - Protein bound Thyroid and Steroid Hormones Remain in circulation much longer Enter bloodstream More than 99% become attached to special transport proteins Bloodstream contains substantial reserve of bound hormones A reserve Why do thyroid and steroid hormones stay in circulation longer? Diagram the general mechanism of action of a lipid soluble hormone. Then, compare and contrast a steroid hormone vs. thyroid hormone mechanisms of action. Yes, they are both lipid soluble hormones, but they have slightly different mechanisms of action. Correct Answer - Lipid soluble hormones: Glucocorticoids Estrogens Androgens Thyroid hormone (T3) Calcitriol (the active form of vitamin _?_) Diffuse across the plasma membrane to reach receptor proteins on inner surface of membrane (intracellular receptors) REMEMBER: Anything that originates from cholesterol is lipid soluble! - Hormones and Intracellular Receptors Alter rate of DNA transcription in nucleus Directly affect metabolic activity and structure of target cell Includes steroids and thyroid hormones Steroid - has a 4 ring structure Lipid soluble, passes right through