MPP 3202 1st Edition Exam # 4 Study Guide Chapters: 21-26 Chapter 21 Homework Questions: 1. Which of the following is NOT considered to be one of the four basic functions of the digestive system? 1. acid-base balance (functions: matching fluid input with output, decreasing the size of food molecules, repelling foreign invaders) 2. Why must the process of lipid digestion be different from proteins and carbohydrates? 1. Lipids are hydrophobic 3. Which long reflex of the cephalic phase stimulates digestive activity in the stomach before food arrives? 1. Vagal reflex 4. In terms of chemical digestion of organic molecules, the stomach primarily digests _______ . 1. Proteins 5. Blood draining from the intestines flows directly to the ________. 1. Liver for filtering 6. In which non-digestive function does the digestive tract play a surprisingly large role? 1. Immunity 7. Which is NOT classified as a member of the secretin family of GI hormones? 1. cholecystokinin (CCK) 8. GI contractions that are sustained for minutes or hours are called ________ contractions. 1. Tonic 9. Crypt cells in the small intestine and colon secrete ________ into the lumen. 1. an isotonic sodium chloride solution 10. What makes the anatomy of the stomach wall unique compared to the other parts of the digestive system? 1. It has three layers of smooth muscle Chapter 22 Homework Questions: 1. Insulin is produced by the ________ cells of the pancreas. 1. beta 2. When the level of the glucose pool falls below normal, which tissue is the only one able to access glucose? 1. brain 3. How does binding of insulin to its receptor cause glucose uptake from the bloodstream? 1. It causes insertion of GLUT4 transporters in the membrane 4. Which pathway is the opposite of lipogenesis? 1. beta-oxidation 5. What happens to excess glucose in the body? 1. It undergoes lipogenesis Chapter 23 Homework Question s: 1. Which is the best example of negative feedback? 1. Thyroid hormone (TH) secreted into the bloodstream causes increased cellular metabolism and increased body temperature, and increased TH levels inhibit TH release. 2. What precursor molecule can be converted to either testosterone or aldosterone? 1. progesterone 3. Which endocrine gland is NOT correctly matched to a hormone it produces? 1. zona reticularis —ACTH 4. How is the hypothalamic control of growth hormone (GH) release different from the control of TSH and ACTH? 1. The hypothalamus releases both stimulatory and inhibitory tropic hormones for GH, whereas it only releases stimulatory hormones for TSH and ACTH. 5. Endocrine pathologies can occur through excess Fertilization of the human egg normally occurs in the ________.secretion, inadequate secretion, and which other mechanism? 1. abnormal target cell response Chapter 26 Homework Questions: 1. Choose the TRUE statement • mechanisms controlling food intake and energy balance are centered in the hypothalamus • Arcuate nucleus = two main types of output neurons: ◦ 1) express POMC ◦ 2) express AgRP and Neuropeptide Y • POMC neurons: ◦ αMSH = agonist for melanocortin receptors: MC3R, MC4R ◦ promote energy expenditure, ↓FI • AgRP neurons: ◦ agouti/NPY = inverse agonist for MC3R/MC4R ◦ oppose melanocortin action; NPY-- ↓ energy use, ↑FI • Both sets of neurons modulated by insulin and leptin (↑POMC activity, ↓AgRP) Endocrine Function: • The hypothalamic-pituitary control system = controlled by hypothalamus and anterior pituitary trophic hormones • Feedback loops = response to hormone • Hormone receptors = may be on cell surface or inside the cell • Cellular Responses = hormone target cells respond by altering existing proteins or making new ones • Modulation of Target Cell Response = up-regulation or down-regulation of hormone • Endocrine Pathologies = result from a) excess hormone secretion, b) inadequate hormone secretion, c) abnormal target cell response Adrenal Gland: • Zona fasciculata of cortex synthesizes and releases glucocorticoids • Cholesterol is the precursor to all steroid hormones Cortisol secretion: • Circadian Rhythm • Metabolic system is diurnally active, mainly entrained by daily cycles of light and dark—our evolutionary legacy • Conditions of human entrainment have changed over last 150 years • Forced adaptation to altered rhythms can promote metabolic dysfunction and disease • Precise mechanisms unknown... ◦ Conflict between biological signals vs. social demands? (shift work) ◦ Asynchrony between brain and periphery? (influx of calories at night) • Effects: ◦ promotes catabolism (similar to glucagon)—protection against hypoglycemia at expense of body protein and fat oxidation ◦ promotes negative calcium balance (decreased absorption, increased excretion, increased bone breakdown) ◦ depresses immune function (inhibitory effects on leukocytes of both innate and adaptive immune systems) ◦ 1) Necessary for full glucagon effect ◦ 2) Suppresses immune fxn/inflammation ◦ 3) Negative Ca2+ balance • Mechanism of Action ◦ Intracellular (cytoplasmic) receptor—ligand-dependent transcription factor ◦ 1. diffusion into cell ◦ 2. binding to receptor ◦ 3. translocation into nucleus ◦ 4. stimulation of gene expression via binding to GRE’s in gene’s promoter ◦ 5. inhibition of gene expression via blocking activity of transcription factors • Therapeutic Drug ◦ Anti-inflammatory ◦ Suppresses B-cell antibody production ◦ inflammatory/ rheumatic diseases & allergies ◦ Use of NSAIDs has replaced that of corticoids for minor inflammatory disorders—avoids corticoids’ metabolic effects • Pathologies ◦ Hypercortisolism (most common) ▪ Cushing’s syndrome ▪ 1) adrenal tumor (1° hypercortisolism) ▪ 2) pituitary tumor (secretes xs ACTH, 2° hypercortisolism, aka “Cushing’s disease”) ◦ Progesterone elicits ↑ in basal body temp (~ 0.3° C) which lasts until onset of menstruation • Stimulation or inhibition of erection can occur with or without input from higher brain centers • Mechanism of penile vasodilatory response & basis for action of Sildenafil, similar vasoactive drugs • In order to become fertilization-competent, sperm must undergo Capacitation in the female reproductive tract • Fertilization—distal part of fallopian tube • Sperm penetrates outer layers via enzymatically-mediated acrosomal reaction • Why are mitochondria maternally inherited? ◦ Mitophagy of sperm-derived mitochondria upon fertilization • Zygote begins dividing in Fallopian tube, implants in uterus as a blastocyst (~ 100 cells) 5-9 days post-fertilization • Human chorionic gonadotropin (hCG) secreted from chorionic villi & placenta: ◦ Binds to LH receptors on corpus luteum ◦ Maintains viability of C.L., which continues to produce progesterone ◦ By roughly 2-3 months, placenta takes over production of hormone ◦ Prog—supports endometrium, inhibits uterine contractions Estr— supports endometrium, development of milk glands • From the 2nd trimester-parturition, placenta takes over production of progesterone, estrogen • Human placental lactogen (hPL): ◦ Secreted by placenta in proportion to placental development ◦ Main function: induce metabolic shift in favor of fetus ◦ ↓ maternal insulin sensitivity results in ↑ maternal blood glucose ◦ ↓ maternal glucose utilization spares glucose for fetus ◦ ↑ lipolysis leads to ↑ FFA for use by mother; glucose and ketone bodies used by fetus ◦ Supports fetal nutrition even under conditions of maternal malnutrition • Labor & Delivery : ◦ Precise initial trigger not clear, but may be secretion of CRH by placenta • Control of Lactation: • Puberty ◦ Maturation of hypothalamic-pituitary axis ◦ Pulsatile secretion of GnRH increases results in an ↑ secretion of LH, FSH • Menopause--female ◦ Cessation of reproduction-competent phase of life—ovulation, menstrual cycles gradually become erratic and ultimately cease ◦ Appears to be due to development of insensitivity to FSH, LH in ovaries leads to decreased production of estrogen, progesterone • Andropause--male ◦ Role of decreased testosterone secretion not clear..