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Chapter 18: Regulation of Organic Metabolism, Growth,and Energy Balance

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Section A. Control and Integration of Carbohydrate, Protein and Fat Metabolism

EVENTS OF THE ABSORPTIVE AND POSTABSORPTIVE STATES

  1. Define:
    2.
    1. Absorptive State:
    2. Postabsorptive State:

    answer
  2. The average time for complete absorption of a meal is hours.

    3. answer

Absorptive State
  1. The three major nutrients that are present in foodstuffs are , , and . The end products of digestion of these nutrients are respectively , , and .

    2. answer

  2. The substances absorbed from the gastrointestinal tract into the blood that pass directly to the liver via the hepatic portal vein are and . The are absorbed into the , which then empties into the general circulation.

    3. answer

Absorbed glucose
  1. The three major fates of glucose during the absorptive phase are:

    answer

  2. In the liver, the glucose that is synthesized into triacylglycerols can be packaged with proteins to be secreted into the blood as .

    3. answer

  3. The VLDL complex (does, does not) readily penetrate capillary walls.

    4. answer

  4. The VLDL triacylglycerols in the blood are hydrolyzed into and by the capillary enzyme . This enzyme is in high concentrations in tissue. Thus the fatty acids generated in adipose tissue can be resynthesized into for storage.

    5. answer

Absorbed triacylglycerols
  1. Triacylglycerols are absorbed from the gastrointestinal tract into the in the form of . The fatty acids are released from the chylomicron triacylglycerols by the enzyme .

    2. answer

  2. When triacylglycerols are formed, the source of the alpha-glycerol phosphate is .

    3. answer

  3. Three major sources of fatty acids found in adipose tissue triacylglycerols are:

    answer

Absorbed amino acids
  1. Most of the absorbed amino acids enter cells and are used for . Excess amino acids are converted to or .

    2. answer

Postabsorptive State

Sources of blood glucose
  1. Blood glucose is generated during the postabsorptive state by:

    answer

  2. The end products of glycogenolysis in the liver and skeletal muscle are and , respectively.

    3. answer

  3. The breakdown of liver glycogen is an immediate source of blood glucose but can supply only about hours of caloric energy.

    4. answer

  4. Using a diagram, show how muscle glycogen can eventually be a source of blood glucose.

    5. answer


  5. Using a diagram, show how triacylglycerols can be a source of blood glucose.

    6. answer


  6. Using a diagram, show how proteins can be a source of blood glucose.

    7. answer


  7. The synthesis of glucose from non-glucose precursors (pyruvate, lactate, glycerol, amino acids) is known as . The primary organ where this occurs is the .

    8. answer

Glucose sparing (fat utilization)
  1. In the transition from absorptive to the postabsorptive state, glucose use is reduced and utilization is increased. This metabolic adjustment is called .

    2. answer

  2. Outline the catabolism of triacylglycerols (in adipose tissue).

    3. answer


  3. The liver, unlike most other cells in the body, converts acetyl CoA from fatty acid metabolism into which can be used as a source of energy during fasting and glucose sparing.

    4. answer

  4. Summarize how plasma glucose can remain nearly normal after several days of fasting.

    5. answer


ENDOCRINE AND NEURAL CONTROL OF THE ABSORPTIVE AND POSTABSORPTIVE STATES

Insulin
  1. Insulin is a (peptide, steroid, amine) hormone released from the cells of the located in the pancreas. Its major effect is to (raise, lower) blood glucose by facilitating the transport of glucose into cells. This is similar to the events that occur during the (absorptive, postabsorptive) state.

    2. answer

  2. The major target organs (or cells) for insulin are:

    3. answer


Effects on muscle and adipose tissue
  1. Glucose enters most cells by the transport process known as .

    2. answer

  2. Insulin facilitates the uptake of glucose by muscle and fat cells by .

    3. answer

  3. In muscle cells, insulin (favors, inhibits) glycolysis, (favors, inhibits) glycogen synthesis, (stimulates, inhibits) glycogen synthase, and (stimulates, inhibits) glycogen phosphorylase.

    4. answer

  4. In fat cells, insulin (favors, inhibits) triacylglycerol synthesis and (favors, inhibits) intracellular lipase.

    5. answer

  5. Insulin (favors, inhibits) cellular uptake of amino acids into most cells.

    6. answer

  6. Overall, insulin favors (anabolic, catabolic) effects. This resembles the (absorptive, postabsorptive) state.

    7. answer

Effects on liver
  1. As in muscle and adipose tissue, insulin's effects on the liver favor glycogen (synthesis, breakdown) and triacylglycerol (synthesis, breakdown).

    2. answer

  2. Insulin's specific effects on liver, not seen in muscle and adipose tissue, include:

    answer

  3. Insulin influences glucose uptake in liver cells by:

    answer

Effects of decreases in plasma insulin concentration
  1. List six major metabolic effects brought about by a decrease in plasma insulin concentration.

    answer

  2. Metabolic effects seen with a decrease in plasma insulin reflect the same metabolic effects that are seen during the (absorptive, postabsorptive) state.

    3. answer

  3. Metabolic effects seen with an increase in plasma insulin reflect the same metabolic effects that are seen during the (absorptive, postabsorptive) state.

    4. answer

Control of insulin secretion
  1. Diagram the feedback loop for the control of insulin secretion.

    2. answer


  2. Explain how glucose-dependent insulinotropic hormone (GIP) controls insulin secretion.

    3. answer


  3. Explain how the autonomic nervous system influences insulin secretion.

    4. answer


Glucagon
  1. The major stimulus for the release of glucagon is .

    2. answer

  2. Glucagon (increases, decreases) plasma glucose and ketones.

    3. answer

  3. Glucagon's effects on the liver include:

    answer

  4. During the absorptive state the glucagon/insulin ratio is (high, low) while during the postabsorptive state this ratio of glucagon/insulin is (high, low).

    5. answer

  5. Sympathetic and parasympathetic innervation of alpha cells in the islets of Langerhans in the pancreas (increase, decrease) glucagon secretion.

    6. answer

Epinephrine and Sympathetic Nerves to Liver and Adipose Tissue
  1. Epinephrine and sympathetic innervation to the pancreas (increase, decrease) insulin secretion and (increase, decrease) glucagon secretion.

    2. answer

  2. Epinephrine and sympathetic innervation to the liver and adipose tissue increase (I) or decrease (D) the following:
    3.
    1. glycogenolysis in liver and skeletal muscle
    2. gluconeogenesis in liver
    3. lipolysis in adipocytes

    answer

Other hormones

Cortisol
  1. Cortisol enhances metabolic effects (similar to, opposite) those of insulin.

    2. answer

Growth Hormone
  1. Growth hormone enhances metabolic effects (similar to, opposite) those of insulin.

    2. answer

  2. Hormones that increase plasma glucose levels are:

    3. answer

  3. Hormones that decrease plasma glucose levels are:

    4. answer

  4. Hormones that increase during the absorptive state are:

    5. answer

  5. Hormones that increase during the postabsorptive state are:

    6. answer

FUEL HOMEOSTASIS IN EXERCISE AND STRESS
  1. What happens to plasma glucose levels during mild exercise?

    2. answer


  2. What happens to plasma glucose levels during severe exercise?

    3. answer


  3. Graph plasma glucose, glucagon, and insulin concentration during prolonged moderate exercise (250 min). Plot plasma levels on the Y axis and time on the X axis.

    4. answer


DIABETES MELLITUS
  1. Differentiate between insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM).

    2. answer


  2. An individual with untreated IDDM would have and increase (I) or decrease (D) in the following:
    3.
    1. plasma glucose
    2. glycogenolysis (liver)
    3. gluconeogenesis (liver)
    4. lipolysis
    5. plasma glycerol and fatty acids
    6. plasma ketones
    7. urinary glucose
    8. urinary ketones
    9. urine volume
    10. blood pH

    answer

  3. A major factor that may predispose and individual to NIDDM is:

    4. answer


REGULATION OF PLASMA CHOLESTEROL
  1. List some functions of cholesterol in the body.

    2. answer


  2. Why are high plasma cholesterol levels dangerous?

    3. answer


  3. Two sources of plasma cholesterol are:

    answer

  4. What is the liver's role in cholesterol metabolism?

    5. answer


  5. Cholesterol synthesis by the liver is (increased, decreased) when dietary cholesterol is increased because cholesterol (stimulates, inhibits) the enzyme critical for cholesterol synthesis by the liver.

    6. answer

  6. Diagram the feedback loop involved in maintaining normal plasma cholesterol in the face of dietary cholesterol changes.

    7. answer


  7. Animal fat is a major source of (saturated, unsaturated) fatty acids which (increase, decrease) plasma cholesterol levels.

    8. answer

  8. Plant oils are a major source of (saturated, unsaturated) fatty acids which (increase, decrease) plasma cholesterol levels.

    9. answer

  9. Plasma cholesterol levels are altered by altering cholesterol through

    answer

  10. A "healthy" plasma cholesterol level is approx. mg/dl.

    11. answer

  11. Cholesterol is carried in plasma as:

    answer

  12. (HDLs, LDLs) carry cholesterol to cells.

    13. answer

  13. (HDLs, LDLs) remove cholesterol from cells.

    14. answer

  14. " Good" cholesterol is carried by (HDLs, LDLs) and "bad" cholesterol is carried by (HDLS, LDLs).

    15. answer

  15. The (higher, lower) the ratio of LDL/HDL, the lower the risk of developing atherosclerotic hear disease.

    16. answer

  16. Indicate whether the following increase (I) or decrease (D) circulating levels of HDLs:
    1. exercise
    2. cigarette smoking
    3. estrogens

    answer


Section B. Control of Growth

BONE GROWTH
  1. Describe how long bones grow in length.

    2. answer


  2. Long bones continue to grow until occurs.

    3. answer

ENVIRONMENTAL FACTORS INFLUENCING GROWTH
  1. The major environmental factors that influence growth are:

    answer

HORMONAL INFLUENCES ON GROWTH

Growth Hormone and Insulin-like Growth Factor 1
  1. Describe the major effects of growth hormone on postnatal growth of long bones. Include IGF-1 (Somatomedin C).

    2. answer


  2. Overproduction of growth hormone during childhood may result in the condition known as , while overproduction of growth hormone in adults after epiphyseal closure may result in the condition known as .

    3. answer

  3. Dwarfism may be caused by:

    answer

  4. Growth hormone stimulates long bone growth indirectly via the mediator known as but stimulates protein synthesis directly.

    5. answer

  5. Diagram the feedback loop for the release of growth hormone.

    6. answer

  6. Other hormones that increase growth hormone secretion are and .

    7. answer

  7. Plasma growth hormone is (higher, lower) during sleep and (higher, lower) during the day.

    8. answer

  8. The 24 hour secretion rate of growth hormone is highest in (children, adolescents, adults).

    9. answer

Thyroid Hormones
  1. Infants and children who are hypothyroid are short of stature. Why?

    2. answer


  2. Thyroid hormones play an important permissive role in central nervous system development. How would the CNS of a hypothyroid newborn be affected?

    3. answer


Insulin
  1. How does insulin help promote growth?

    2. answer


Sex Hormones
  1. How do sex hormones help promote growth?

    2. answer


  2. How do sex hormones ultimately stop bone growth?

    3. answer


  3. How do testosterone-like agents (anabolic steroids) increase muscle mass?

    4. answer


Cortisol
  1. The antigrowth affects of cortisol are due to:

    2. answer


    Review the SUMMARY and REVIEW QUESTIONS at the end of this section in your textbook.


Section C. Regulation of Total-Body Energy Balance and Temperature

BASIC CONCEPTS OF ENERGY EXPENDITURE AND CALORIC BALANCE
  1. When organic molecules are broken down, the energy liberated can appear either as or .

    2. answer

  2. Complete this equation: E = +

    3. answer

  3. Approximately percent of energy released during metabolism appears as heat.

    4. answer

  4. Total energy expenditure = heat + + .

    5. answer

Metabolic Rate
  1. Define:
    1. Metabolic rate:
    2. Kilocalorie (kcal):

    answer

Determinants of Metabolic Rate

Basal Metabolic Rate (BMR)
  1. Define BMR:

    2. answer


  2. A child's BMR is (equal to, greater than, less than) an adult's BMR.

    3. answer

  3. A female's BMR is (equal to, greater than, less than) a male's BMR.

    4. answer

  4. A pregnant woman's BMR is (equal to, greater than, less than) a nonpregnant woman's BMR.

    5. answer

  5. Indicate whether the following will cause an individual's metabolic rate to increase (I) or decrease (D).
    1. thyroid hormones
    2. epinephrine
    3. food ingestion
    4. skeletal muscle activity

    answer

Total Body Energy Balance
  1. Energy from food ingested = + + .

    2. answer

Control of Food Intake
  1. Diagram the inputs that control food intake. Indicate which inputs stimulate hunger (+) and which inhibit (-) hunger.

    2. answer


Obesity

  1. What is your body weight?

    2. answer


  2. According to the body mass index (BMI) do you fall within the normal range? Include the formula for BMI.

    3. answer


  3. Obesity is defined as percent over the "desirable" body weight.

    4. answer

  4. Two valuable components in a sensible weight loss program include:

    answer

  5. If an individual's metabolic rate/24 hours is 2400 kcal, and the dietary intake is 1500 kcal/day, how many grams of body fat will be burned/day? Show your work.

    6. answer


  6. How long will it take for this individual to lose one pound of body weight? Show your work.

    7. answer


Eating Disorders: Anorexia Nervosa and Bulimia
  1. Differentiate between anorexia nervosa and bulimia.

    2. answer


REGULATION OF BODY TEMPERATURE

Mechanisms of Heat Loss or Gain
  1. State and briefly describe four mechanisms by which the body can lose heat to the external environment.

    answer

Temperature-Regulating Reflexes
  1. Diagram the temperature-regulating mechanism involved in regulating body temperature. Start with the peripheral thermoreceptors and central thermoreceptors. Include efferent output and effectors.

    2. answer


Control of heat production
  1. The major control of heat production for temperature regulation is . This results in an increase in internal heat and is thus known as .

    2. answer

Control of heat loss by radiation and conduction
  1. Ways of regulating heat loss by radiation and conduction are:

    2. answer


Control of heat loss by evaporation
  1. Describe insensible water loss.

    2. answer


  2. Differentiate between the cooling effect of sweating on a humid day versus a non-humid day.

    3. answer


Integration of effector mechanisms
  1. Core body temperature can be regulated in environmental temperatures in the thermoneutral zone by .

    2. answer

  2. Environmental temperatures above the thermoneutral zone require the body to compensate by .

    3. answer

  3. Environmental temperatures below the thermoneutral zone require the body to compensate by .

    4. answer

Temperature Acclimatization

Acclimatization to heat
  1. During heat acclimatization, there is a(n) (increase, decrease) in the volume of sweat produced. There is also a decrease in the loss of sodium in sweat due to the increase in the hormone .

    2. answer

Acclimatization to cold
  1. One of the major factors in cold acclimatization is .

    2. answer

Fever
  1. During fever, the hypothalamic setpoint for temperature regulation is reset. The basis for this "resetting" may be:

    2. answer


  2. The hyperthermia accompanying exercise is due to .

    3. answer

     

    Review the SUMMARY and REVIEW QUESTIONS at the end of this section and the THOUGHT QUESTIONS at the end of this chapter in your textbook.

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