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25 Cards in this Set
- Front
- Back
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Compare/contrast the absorptive and postabsorptive states including when they occur relative to eating.
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Absorptive State
-period during and 4 hours after a meal -nutrients enter the blood from the GI tract Postabsorptive State -nutrients are provided from body stores -for humans is during late morning, late afternoon, and during the night -fasting = > 24h without eating |
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The Absorptive State: Fate of Amino Acids
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amino acids (from proteins) and monosaccharides (from carbs) go by way of hepatic portal vein from GI tract to liver
after liver modifies blood composition it goes to heart for distribution to rest of body |
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The Absorptive State: Fate of Triglycerides
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triglycerides (from fat) enter lymph as chylomicrons and from there enters blood
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Briefly describe the major challenge in meeting the body's requirement for energy during the postabsorptive state.
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main challenge of postabsorptive state is to maintain an adequate supply of glucose to the CNS
Accomplished by: -mechanisms that maintain plasma glucose -glucose "sparing" by non-neural cells which switch to use of fats for fuel |
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When does each mechanism (glycogenolysis, gluconeogenesis, glucose sparing) come into play during postabsorptive period?
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Glycogenolysis by liver is body's first line of defense for maintaining blood sugar (rapid response)
Gluconeogenesis is second |
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Briefly compare glucose-producing to glucose-sparing mechanisms in terms of the proportion of total energy each supplies.
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Glucose sparing supplies 1/2-3/4 of calories required in postabsorptive period
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Name the two most important hormones to play a role in the shifts in energy sources between the absorptive and postabsorptive states.
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insulin & glucagon
produced in pancreas |
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Name the cells that produce insulin & glucagon and tell where they are located.
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Insulin and glucagon are both peptide hormones
insulin produced by beta (B) cells in pancreas glucagon produced by alpha (A) Islet of Langerhans cells in pancreas |
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Which compound is the most important for control of organic metabolism?
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Insulin
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What happens to insulin levels during the absoptive and postabsorptive states and how do the effects of insulin relate to the activities typical of these states?
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Insulin secretion rises during absoptive states and falls in postabsorptive states
effects of insulin rise and fall = the major events of teh absorptive and postabsorptive states |
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Describe insulin-regulated glucose transport across cell membranes and the various mechanisms and factors that control/influence insulin secretion.
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GLUT-4 is the insulin-regulated glucose transporter in muscle and adipose tissue
-elevated insulin causes vesicles with GLUT-4's to fuse to plasma membrane -more GLUT-4's = increased uptake of glucose by facilitated diffusion a feedback mechanism involving plasma glucose levels is the major regulator of insulin secretion from beta cells plasma amino acids increase insulin secretion incretins are hormones from GI tract that amplify insulin response to glucose eating stimulates parasympathetic nervous system to increase insulin secretion from B cells situations (exercise,stress,etc.) in which sympathetic nervous system is activated --> decreases insulin secretion from B cells |
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List the major glucose counter-regulator controls that oppose the action of insulin.
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glucagon, epinephrine, sympathetic nervous system input, cortisol, growth hormone
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What controls glucagon release?
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glucagon release is governed by plasma glucose levels
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Compare the pattern of glucagon releaseto that of insulin.
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Pattern of release is opposite that of insulin
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What factors trigger glucagon release and what is the significance of this to the postabsorptive state?
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Major stimulus of glucagon release is a decrease in blood glucose
increased release is major factor in shift to postabsorptive period |
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List the effects of elevated glucagon on the liver and describe the results of these processes on plasma glucose and ketone levels
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Increase in plasma glucagon acts primarily on liver to increase glucogeogenesis, glycogenolysis, ketone synthesis
result is maintenance of plasma glucose and ketone levels |
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Describe how the sympathetic nervous system monitors blood glucose and the direct and indirect ways in which it can affect metabolism.
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sympathetic nervous system acts directly through neural contacts and indirectly by releasing epinephrine from adrenal medulla into blood
low plasma glucose --> increased sympathetic system activity |
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List the factors that maintain muscle energy levels during exercise.
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-decreased insulin secretion and increased glucagon secretion
-increased sympathetic nervous system activity -increased secretion of cortisol and GH |
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Effect of Exercise on Metabolism
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most responses of skeletal muscle, liver and fat tissues to provide fuel for exercise are same as for maintaining plasma glucose during fasting
major difference of exercise from fasting is that glucose uptake by muscles during exercise is increased small decrease in plasma glucose seen only in prolonged exercise (>90 min) nonspecific stresses cause same patern as for exercise (preparation for "fight or flight") |
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Describe some effects of chronic intense exercise on the body.
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-adolescent athletes may have delayed puberty
-adult women may have infertility due to exercise-induced amenorrhea (absense of menstruation) |
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Diabetes Mellitus Type I
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15,000,000 people in US
10% of diabetics results from autoimmune destruction of beta cells -elevated blood glucose -increased lipolysis -elevated plasma ffa and glycerol -increased liver production of ketones -osmotic diueresis -weight loss -low blood pressure -diabetic ketoacidosis -brain damage, coma, death treated by insulin therapy |
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Diabetes Mellitus Type 2
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90% of diabetics
obesity --> insulin resistance in cells beta cells may also make less insulin treatments weight loss and exercise drugs to decrease plasma glucose drugs to increase cell responsiveness to insulin insulin |
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Hypoglycemia
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abnormally low blood glucose in postabsorptive state
causes excess of insulin due to tumor, taking too much insulin in diabetes, other drugs deficiency of glycogenolysis/gluconeogenesis resulting from conditions such as liver disease or problems of glucagon or cortisol secretion symptoms increased heart rate, swelling, sweating, anxiety headache, confusion, dizziness, slurred speech |
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List sources of cholesterol in the body and describe pathways for removal.
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-dietary from animal foods
-synthesized by body, especially liver and GI tract pathways of removal: -lost in feces -liver picks up some from blood and secretes it into the bile or metabolizes it to bile salts |
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Describe the role of the liver in control of cholesterol levels.
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liver major regulator of plasma cholesterol
-if high due to diet, production by liver decreases -if low, production by liver increases increased by ingestion of saturated fats decreased by ingestion of mono or polyunsaturated fats |
