Digestive and Endocrine Systems: An Overview of Hormonal Control and Nutrient Absorption, Exams of Biology

Download Digestive and Endocrine Systems: An Overview of Hormonal Control and Nutrient Absorption and more Exams Biology in PDF only on Docsity! P a g e 1 | 7 1 WSU Bio 251 Final Exam well answered solution 2024 The four major processes that occur in the digestive system. - ANS>> 1. Motility 2. Secretion 3. Digestion 4. Absorption Motility - ANS>> Contractions of smooth muscle in the walls of the digestive tract Secretion - ANS>> Movement of substances into digestive tract lumen Digestion - ANS>> Biochemically breakdown nutrients (carbohydrates, fats, proteins) into smaller absorbable units (monosaccharides, fatty acids, amino acids) Absorption - ANS>> Small absorbable units are transferred from digestive tract into blood or lymp Which stomach cells secrete hydrochloric acid (HCl)? What is the mechanism of HCl secretion? - ANS>> -Parietal Cells - What are the signals for HCl secretion? - ANS>> 1. Parasympathetic nervous system (ACh) 2. Gastrin (a hormone) 3. Histamine (a paracrine; produced by cells in the stomach) Which stomach cells secrete pepsinogen? How is pepsinogen activated? What is the function of pepsin? - ANS>> -Chief cells -Activated by HCl -Pepsin: enzyme that breaks down protein The majority of carbohydrate, fat, and protein digestion occurs in which organ? - ANS>> Small intestine List the primary digestive enzymes of the pancreas. - ANS>> a) Pancreatic amylase (similar to salivary amylase): starch → maltose b) Trypsin, chymotrypsin: proteins → amino acids and small peptides c) Pancreatic lipase: fat → monoglycerides and fatty acids What are the mechanisms for absorption of each type of nutrient absorbable unit from the digestive tract? - ANS>> P a g e 2 | 7 2 Describe the steps in carbohydrate digestion (both disaccharides and polysaccharides) and how the digestion products are absorbed out of the digestive tract. - ANS>> What is the mechanism for amino acid absorption? - ANS>> 1. Cross apical membrane by sodium linked-secondary active transport or facilitated diffusion a) Different transporters for different amino acid types 2. Cross basolateral membrane by facilitated diffusion What is the mechanism for di, and tripeptide absorption? - ANS>> 1. Cross apical membrane by secondary active transport 2. Broken down inside cell to amino acid 3. Amino acids cross basolateral membrane by facilitated diffusion What are the steps involved in the digestion of triglycerides and the absorption of monoglycerides and fatty acids? - ANS>> -Triglycerides → monoglyceride and 2 fatt acids -Monoglycerides and fatty acids are lipid soluble: can be absorbed by simple diffusion across epithelial cell membrane What are micelles? - ANS>> Shield non-polar parts from water allowing the fatty acids and monoglycerides to remain in solution What are chylomicrons? - ANS>> Triglycerides and proteins and cholesterol What is the major process that occurs in large intestine (colon)? - ANS>> Absorption of most remaining water (about 400 ml) not absorbed by the small intestine What are at least two functions of cholecystokinin (CCK)? - ANS>> a) stimulates pancreatic cells b) CCK secreted from endocrine cells in small intestine in response to fats and amino acids entering the duodenum c) CCK travels to pancreas in blood What is the function of secretin? - ANS>> a) Hormone that stimulates pancreas to secrete a fluid with high bicarbonate (HCO3-) concentration b) Secretion also released from small intestine but in response to acid c) Bicarbonate enters duodenum and helps neutralize any acid entering from the stomach What are the functions of insulin and glucagon? What cells secrete insulin and glucagon? - ANS>> -Insulin: primary hormone of absorptive state 1. Promotes synthesis of nutrient storage molecules 2. Promotes glucose use for energy -Glucagon 1. Mobilization of energy stores 2. Synthesis new glucose P a g e 5 | 7 5 1. Metabolic actions supporting growth a) Inhibit glucose uptake into adipose tissue and skeletal muscle b) Stimulates lipolysis in adipose tissue c) Stimulate gluconeogensis in liver d) Increase uptake of amino acids into cells What role do insulin-like growth factors (somatomedins) play in growth hormone related effects? - ANS>> Somatomedins have direct effect on target cells to cause cell proliferation and growth Which cells synthesize insulin-like growth factors (somatomedins)? - ANS>> GH stimulates liver cells to secrete molecules called somatomedins (insulin-like growth factors) Describe the effects of an abnormal secretion of growth hormone, include what happens with both elevated secretion and reduced secretion. - ANS>> 1. Gigantism a) Increased GH secretion in children (before puberty) b) Body features in proportion 2. Acromegaly a) Increased GH secretion in adults (after puberty) b) Causes bone thickening c) disfiguring condition 3. Dwarfism a) Decreased GH secretion or failure of cells to respond to GH in children b) long bone (legs, arms, fingers) shortened What are the primary functions of thyroxine (thyroid hormone)? - ANS>> 1. Causes increased metabolic rate--more energy (ATP utilization) 2. Increased heat production 3. Increased heart rate/contraction force of heart (heart cells more responsive) 4. Necessary for proper growth and development of nervous system What are the two primary forms of thyroxine? Which form is primarily secreted from the thyroid gland? Which form has the most biological activity? - ANS>> 1. T4 a) Contains 4 iodide atoms b) Most abundant form produced c) Least active d) Does provide negative feedback on TSH secretion 2. T3 a) Contains 3 iodide atoms b) Not as much made c) Most active form of thyroid hormone What are the primary functions of cortisol? - ANS>> Primary action is to increase blood glucose concentration P a g e 6 | 7 6 1. Increases gluconeogensis in liver 2. Increases protein breakdown--amino acids can be used for gluconeogensis 3. Increases fat breakdown--fatty acids used by most cells for energy Which cells secrete cortisol? - ANS>> Secreted by cells in adrenal cortex a) stimulated by ACTH from anterior pituitary What is the control mechanism for cortisol secretion? - ANS>> Negative feedback Describe what happens if cortisol secretions are abnormal, I.e. either hyper- or hyposecretion - ANS>> 1. Cushing's Syndrome: hypersecretion a) Hyperglycemia b) Protein depletion → wasting away of muscle, especially in arms and legs c) Deposition of fat in belly and face d) Degeneration of capillaries (causes local hemorrhages) 2. Addison's disease: hyposecretion a) Hypoglycemia b) Poor tolerance fors tress What are the control mechanisms for testosterone secretion? - ANS>> Leydig cells are stimulated by LH from anterior pituitary glad a) Testosterone secretion controlled by LH b) Testosterone has a negative feedback mechanism on LH secretion Which cells secrete testosterone? - ANS>> Leydig cells: secrete testosterone a) Located outside of seminiferous tubules What are the functions of testosterone? - ANS>> 1. Before birth: development of male reproductive system (testes, ducts) 2. At puberty: ensures maturation of male reproductive system a) Enlarges testes and accessory sex glands b) Initiates sperm production c) Stops long bone growth 3. Development of secondary sex characteristics (starts at puberty) a) Deepens voice b) Increased muscle development c) Increased body hair d) Increased sex drive e) Increased aggression What are the functions of LH, FSH, estrogen, and progesterone? - ANS>> LH: FSH: Estrogen: Progesterone: What cells secrete estrogen? - ANS>> Grahulosa cells and thecae cells P a g e 7 | 7 7 What is a corpus luteum? - ANS>> Ruptured follicle becomes a glad = corpus luteum What are the two major phases of the uterine cycle? - ANS>> 1. Follicular phase a) Menstruation → ovulation b) ~14 days 2. Luteal phase a) Ovulation → before menstruation b) 14 days Describe what is happening during each phase of the uterine cycle. - ANS>> Phase 1- Follicular 1. A few (10-20/ovary) primary follicles begin to develop under the influence of follicle stimulating hormone (FSH) from anterior pituitary 2. Oocyte grows, granulose cells proliferate to form several layers around oocyte a) Primary follicles become secondary 3. At this time, specialized connective tissues cells differentiate into a layer of cells that surround the developing follicles Phase 2- Luteal 1. After ovulation, ruptured follicle becomes a gland = corpus luteum 2. Corpus luteum secretes estrogen and progesterone 3. Blood capillaries increase in corpus luteum What is the endometrium of the uterus? Which hormone primarily leads to the development of a highly vascularized endometrium during the uterine cycle? - ANS>> Endometrium: tissue lining the inner cavity of the uterus -Progesterone (and estrogen) from corpus luteum maintain the thickened, highly vascularized endometrium of uterus What is the function of progesterone during pregnancy? - ANS>> Placenta starts to now secrete progesterone to maintain the pregnancy What is the primary function of human chorionic gonadotropin? - ANS>> hCG maintains function of the corpus luteum in ovary -Maintains secretion of progesterone and estrogen by ovary -hCG detected in urine by home pregnancy tests What is the function of oxytocin? - ANS>> Oxytocin is a powerful stimulant for uterine contraction What is the feedback mechanism that leads to an increased secretion of oxytocin during childbirth? - ANS>> Positive feedback