NUR 612 Practice Exam Questions and Correct Answers

Explain the role of hormones, the makeup of hormones, and the half-life of hormones Role: Endocrine system uses chemical substances called hormones as a means of regulating and integrating body functions. The are moderators of cellular response Makeup: They can be water soluble (poly-peptide and amino acid derivatives) and fat soluble (steroid) Half-life: there is a postivie relationship between the amount of time the hormone is bonded to its carrier and half life. Explain the function of a hormone receptor and the difference between cell-surface hormone receptors and intracellular hormone receptors. Hormone receptors are linked to one or more effector system in the cells. Protein-based hormones exert their effects by binding to surface receptors on cell membranes. The binding of the hormone may act to stimulate the activity of second messengers (i.e., cAMP). Alternatively, the binding may initiate a direct response by the cell by causing ion (i.e., calcium) channels to open. Steroid hormones are fat soluble and therefore pass directly through the cell membrane. Once inside the cell, they bind to intracellular receptors. These hormone-messenger complexes move to the nucleus and act to stimulate or suppress the gene activity of the cell. Whether by surface or intracellular receptors, hormones act to alter the protein synthesis and therefore function of the cell. Describe the role of the hypothalamus in regulating pituitary control of endocrine function. The hypothalamus and pituitary form a unit that exerts control over many functions of several endocrine glands. Often the hypothalamus secrets a hormone that stimulates/inhibits another hormone in the pituitary gland that acts on a target organ. They are also involved in negative feedback. Explain how postivie feedback loops work Positive feedback mechanisms control self-perpetuating events that can be out of control and do not require continuous adjustment. In positive feedback mechanisms, the original stimulus is promoted rather than negated. It is rarely used to promote homeostasis. Exs: oxytocin during labor, estrodiol/FSH in menstrual cycle. Negative feedback loops Negative feedback mechanisms act like a thermostat in the home. As the temperature rises (deviation from the ideal normal value), the thermostat detects the change and triggers the air-conditioning to turn on and cool the house. Once the temperature reaches its thermostat setting (ideal normal value), the air conditioning