endocrine system chapter 16 Flashcards

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1. The endocrine system is more closely associated
with growth and development, and its responses tend to be long-lasting, whereas
nervous system responses tend to be rapid and discrete.



2. The thyroid and para-thyroid glands are found in the neck.



3. Hormones are released into the blood and transported throughout the body, whereas paracrines act locally, generally
within the same tissue.



Endocrine glands, on the other hand, do not have
ducts and instead secrete hormones into the blood.



5. Steroid hormones are synthesized on the membrane of the smooth endoplasmic reticulum.



6. Steroids are all lipid soluble. Thyroid hormones are the
only amino acid-based hormones that are lipid soluble.



8. Hormone release can be triggered by humoral, neural, or hormonal stimuli.

9. Lipid-soluble hor mones have longer half-lives, meaning that they stay in the blood longer. (They are not as readily excreted by the kidneys because they are bound to plasma proteins, and most need to be metabolized by the liver before they can be excreted.)

10. The hypothalamus communicates with the anterior pituitary via hormones
released into a special portal system of blood vessels. In contrast, it commu nicates with the posterior pituitary via action potentials traveling down axons that connect the hypothalamus to the posterior pituitary.

11. Drinking alcoholic beverages inhibits ADH secretion from the posterior pituitary and causes copious urine output and dehydration. The dehydration causes the hangover effects.

12. LH and FSH are tropic hormones that act on the gonads, TSH is a tropic hormone that acts on the thyroid, and ACTH is a tropic hormone that acts on the adrenal cortex. (If you said growth hormone, that's also a good answer, as GH causing the liver to release IGFs might also be considered a tropic effect.)

13. TA has four bound iodine atoms, and Ty has three. T, is the major hormone secreted, but Ty is more potent. Te is referred to as thyroxine.

14. Thyroid hormone must be carried through blood by plasma proteins because it is lipid soluble and so
does not readily dissolve in blood, which is mostly water. The receptors for TSH (thyroid-stimulating hormone) are located on the plasma membrane of the thyroid follicular cells (on the sides facing away from the colloid). (Recall that TSH is a water-soluble hormone from the anterior pituitary.)

15. Thyroid hormone increases basal metabolic rate (and heat production) in the body. Parathyroid hormone increases blood Ca?+ levels in a variety of ways. Calcitonin at high (pharmacological) levels has a Ca?+-lowering, bone-sparing effect. (At normal blood
levels its effects in humans are negligible.)

16. Thyroid follicular cells release thyroid hormone, parathyroid cells in the parathyroid gland release parathyroid hormone, and parafollicular (C) cells in the thyroid gland release calcitonin.

17. Glucocorticoids are stress hormones that, among many effects, increase blood glucose. Mineralocorticoids increase blood Na+ (and blood pressure) and decrease blood K*. Gonadocorticoids are male and female sex hormones that are thought to have a variety of effects (for example, contribute to onset of puberty, sex drive in women, pubic and axillary hair development in women).

18. The two major stimuli for aldosterone release are (1) a decrease in blood volume or blood pressure, which triggers the renin-angiotensin-aldosterone mechanism, and (2) an increase in plasma K* levels. The major stimulus for cortisol secretion is ACTH from the anterior pituitary. ACTH release, in turn, is controlled by CRH from the hypothalamus. CRH release follows a diurnal (day-night) rhythm
and is increased in response to various stressors, as well as by hypoglycemia and fever.

19. The adrenal cortex (a) releases steroid hormones. The adrenal
medulla (b) and anterior pituitary (c) and posterior pituitary (d) all release amino acid-based hormones. ACTH from the anterior pituitary acts to cause release of steroid hormones from the adrenal cortex. Both the adrenal medulla (b) and posterior pituitary (d) are composed of nervous tissue rather than the glandular
tissue (a type of epithelial tissue) that other glands are made of

20. Melatonin is
used by some individuals as a sleep aid, particularly to counter jet lag.

21. The heart produces atrial natriuretic peptide (ANP). ANP decreases blood volume and blood pressure by increasing the kidneys' production of salty urine.

22. The major function of vitamin Da, produced in inactive form by the skin, is to increase intestinal absorption of calcium. 23. Diabetes mellitus is due to a lack of insulin production or action, whereas diabetes insipidus is due to a lack of ADH. Both conditions are characterized by production of copious amounts of urine.
You would find glucose in the urine of a patient with diabetes mellitus, but not in the urine of a patient with diabetes insipidus.

24. The gonadal hormones are steroid hormones. A major endocrine gland that also secretes steroid hormones is
the adrenal cortex.