2 Problem set 4

2 Problem set 4 - BILD 2, Multicellular Life—Problem...

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Unformatted text preview: BILD 2, Multicellular Life—Problem set #4 1. What is the difference between an endocrine gland and an exocrine gland? How can the pancreas be both an endocrine gland AND an exocrine gland? 2. The anterior pituitary secretes a number of hormones, all of which are peptides. a. How are these hormones delivered to the cells that they affect? b. What determines which cells will respond to each of the hormones? (We call the cells that respond to a hormone the hormone's "target cells.") c. What determines the effect that each of the hormones will produce in their target cells? 3. Epinephrine (a hormone that is a modified amino acid) is secreted by the cells at the core of the adrenal gland. That part of the adrenal gland is called the adrenal medulla. Sympathetic neurons that make synapses onto target organs (not onto other neurons) also release a little epinephrine as a minor component of their neurotransmitter, which is mostly nor ­epinephrine. a. Can you predict whether epinephrine is likely to be hydrophilic or hydrophobic? If so, make the prediction and BRIEFLY support your answer. If not, state what additional information you are likely to need. b. By what mechanism do you expect epinephrine that is released as a hormone to affect postsynaptic cells? Be sure to include a complete description of the mechanism. c. Would you expect that epinephrine that is released as a neurotransmitter would act through a different mechanism? Why or why not? d. If both types of epinephrine signaling were triggered at the same instant, which signal would affect its targets the fastest? BRIEFLY support your answer. 4. A steroid hormone called cortisol is secreted by cells in the outer layer of the adrenal gland. That part of the adrenal cortex is called the adrenal cortex. Cortisol affects a large number of cells distributed widely in the body. It is known as a "stress hormone," and its general effects are an increase in [glucose]plasma and reduction of both the immune response and inflammation. a. Is cortisol likely to be hydrophilic or hydrophobic? If so, make the prediction and BRIEFLY support your answer. If not, state what additional information you are likely to need. b. By what mechanism is cortisol likely to affect its target cells? Be sure to include a complete description of the mechanism. BILD 2, Multicellular Life—Problem set #3 Page 2 c. Typically if a gland secretes more than one hormone, all of the hormones belong to the same chemical family. How can the adrenal gland produce these two different hormones? d. The secretion of cortisol is controlled by a hormone called adrenocorticotrophic hormone (ACTH). Where does ACTH come from, and what controls the release of ACTH? 5 State the characteristics and location of each of the following components: a. Tendons b. Muscle fibers c. Sarcomeres d. Transverse tubules (T ­tubules) 6. In a skeletal muscle fiber, what would you expect to find in: a. Myofibrils b. Thick filaments c. Thin filaments d. Sarcoplasmic reticulum 7. State how each of the following components contributes to the production of force by skeletal muscle fibers. a. Myosin b. Actin c. Troponin d. Tropomyosin e. ATP f. Ca2+ BILD 2, Multicellular Life—Problem set #3 Page 3 8. Now for the question that I promised you: Rigor mortis is produced in all skeletal muscles after death. In this condition, the muscles in the body become rigid, so the body becomes stiff. This condition typically comes on over the course of a few hours, and it typically lasts about 3 days (but temperature has a strong effect on the time course). What about death would cause muscles to become rigid? ...
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This note was uploaded on 02/18/2012 for the course BILD 2 taught by Professor Schroeder during the Spring '08 term at UCSD.

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