Physiology of Metabolism and Circadian Rhythms
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Questions and Answers

What is the effect of genetic disruption of the clock gene in mice?

  • Leads to leaner mice with higher metabolism
  • Enhances glucose uptake in body cells
  • Results in fat mice with altered metabolism (correct)
  • Increases insulin production significantly

Which cells in the pancreas are primarily responsible for insulin secretion?

  • Delta cells
  • Beta cells (correct)
  • Gamma cells
  • Alpha cells

What happens to blood glucose levels after a meal?

  • They are converted to glucagon
  • They rise and stimulate insulin release (correct)
  • They remain constant
  • They decrease significantly

What is the role of glucagon in relation to insulin?

<p>Acts as an antagonist of insulin (A)</p> Signup and view all the answers

How do the wild-type mice compare with the Bmal1 knockout mice in terms of VO2 levels?

<p>Wild-type mice show higher VO2 levels than Bmal1 knockout mice (A)</p> Signup and view all the answers

What does the Respiratory Exchange Ratio (RER) measure?

<p>The proportion of carbohydrates and lipids used for energy (C)</p> Signup and view all the answers

During which period do humans primarily utilize carbohydrates for energy?

<p>Active period (night) (C)</p> Signup and view all the answers

What was the average reduction in caloric intake reported in subjects after applying a 12-hour feeding time restriction?

<p>20% (C)</p> Signup and view all the answers

What is the primary purpose of calculating VO2 and VCO2 in relation to energy expenditure?

<p>To identify which metabolite is being utilized (D)</p> Signup and view all the answers

What is one potential consequence of shift workers burning less energy while asleep?

<p>Accumulation of fat due to higher energy intake (A)</p> Signup and view all the answers

What phenomenon does the term 'Time-Restricted Feeding' refer to?

<p>Restricting the time window for eating without calorie reduction (D)</p> Signup and view all the answers

How does the energy expenditure in daytime compare to nighttime for shift workers?

<p>There is no significant difference in daytime energy expenditure after a night shift (C)</p> Signup and view all the answers

What method is used to measure individual resting metabolic rate?

<p>Human indirect calorimeter (B)</p> Signup and view all the answers

What impact does simulated shiftwork have on metabolic rate during sleep?

<p>It decreases metabolic rate significantly (B)</p> Signup and view all the answers

If shift workers burn less energy at night but maintain their food intake, what is the likely outcome?

<p>Gain in body fat (B)</p> Signup and view all the answers

What initiates the release of insulin by the pancreas?

<p>Rising blood glucose levels (C)</p> Signup and view all the answers

What happens to insulin release when blood glucose levels fall to set point?

<p>Insulin release diminishes (B)</p> Signup and view all the answers

What role does glucagon play when blood glucose levels drop?

<p>Stimulates the liver to convert glycogen to glucose (B)</p> Signup and view all the answers

Which condition would most likely stimulate the release of glucagon?

<p>After skipping a meal (D)</p> Signup and view all the answers

What substance do cells switch to using for energy when insulin levels are low?

<p>Glycogen and fat (B)</p> Signup and view all the answers

What is the set point for blood glucose levels typically around?

<p>90 mg/100 mL (C)</p> Signup and view all the answers

Where is glucagon released from in the body?

<p>The pancreas's alpha cells (D)</p> Signup and view all the answers

What happens to blood glucose levels when insulin is no longer released?

<p>Blood glucose levels begin to fall (A)</p> Signup and view all the answers

What is a potential outcome for patients in the 'Intervention' group who receive IV feeding only during the daytime?

<p>They experience quicker recovery and earlier discharge. (B)</p> Signup and view all the answers

What happens to peripheral oscillators associated with metabolism when feeding occurs at irregular times?

<p>They may become dysynchronized. (A)</p> Signup and view all the answers

How does metabolic dys-synchrony affect calorie burning?

<p>It leads to weight gain and lower calorie burning. (C)</p> Signup and view all the answers

What effect does eating before bedtime have on metabolism?

<p>It may delay the switch into lipid burning mode. (A)</p> Signup and view all the answers

What is a common physiological effect experienced by individuals with Night Eating Syndrome?

<p>Increased insulin resistance at night. (C)</p> Signup and view all the answers

If a student has irregular eating patterns, what metabolic consequence may occur?

<p>Increased likelihood of weight gain. (D)</p> Signup and view all the answers

What can be a consequence of consuming decaf coffee while snacking late at night?

<p>Interferes with the normal glucose/insulin relationship. (B)</p> Signup and view all the answers

What is indicated as a primary reason for rapid discharge and recovery in the 'Intervention' group?

<p>Daytime restrictions promoting better metabolic function. (D)</p> Signup and view all the answers

What role does the Food Entrainable Oscillator (FEO) have in relation to daily rhythms?

<p>It functions independently of the suprachiasmatic nucleus (SCN). (D)</p> Signup and view all the answers

Which statement correctly describes the relationship between the FEO and clock genes?

<p>FEO activity can be altered by clock gene disruptions, but it does not cease. (C)</p> Signup and view all the answers

What does anticipatory activity refer to in the context of FEO?

<p>Movement patterns that occur before food becomes available. (C)</p> Signup and view all the answers

Which of the following components is NOT needed for FEO behavior?

<p>The suprachiasmatic nucleus (SCN). (A)</p> Signup and view all the answers

How does the FEO relate to the concept of rhythmic anticipation during fasting?

<p>The FEO enhances rhythmic anticipation regardless of fasting state. (B)</p> Signup and view all the answers

Which statement about the organization of the mammalian circadian system is false?

<p>The FEO primarily operates within the activities orchestrated by the SCN. (D)</p> Signup and view all the answers

What are possible implications of the FEO on challenges such as jet lag and shift work?

<p>FEO behavior may enhance adaptation to sudden changes in meal timing. (B)</p> Signup and view all the answers

Which physiological process is closely associated with food availability in the context of FEO?

<p>Anticipatory locomotor activity. (C)</p> Signup and view all the answers

Flashcards

Clock gene disruption in mice

Disrupting the clock gene in mice can lead to fatter mice.

VO2 in Bmal1-ko mice

Bmal1 knockout mice show lower VO2 levels than wild-type mice.

Insulin's role in glucose regulation

Insulin, secreted by beta cells in the pancreas, facilitates glucose uptake by body cells.

Glucagon's role in glucose regulation

Glucagon, secreted by alpha cells, counteracts insulin's effect, increasing blood sugar.

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Pancreas' Role in Glucose Regulation

The pancreas regulates blood glucose by producing and secreting insulin and glucagon, which control blood sugar in the body.

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Insulin's role

Insulin helps cells take in glucose and store it as glycogen or fat.

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Blood glucose level homeostasis

The body maintains blood sugar levels within a healthy range.

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Glucagon's role

Glucagon stimulates the liver to release glucose into the blood when blood glucose levels drop.

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Blood Glucose Set Point

The target range of blood glucose level maintained by the body

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Glycogen role in glucose regulation

Glycogen serves as a storage form of glucose in the body.

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Insulin release stimulus

Insulin is released when blood glucose levels rise.

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Glucagon release stimulus

Glucagon is released when blood glucose levels fall.

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RER

Respiratory Exchange Ratio, a measure of how much CO2 is produced relative to the amount of O2 consumed during respiration.

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What does RER tell us?

RER indicates the primary fuel source used for energy production: a higher RER means more carbohydrates, while a lower RER suggests more fat utilization.

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Time-Restricted Feeding

A dietary strategy where you eat within a shorter window of time each day, while restricting calories consumed outside that period.

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Impact of Time-Restricted Feeding

Time-restricted feeding can lead to a significant reduction in calorie intake, even without restricting overall calorie consumption.

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How does Time-Restricted Feeding affect Energy Expenditure?

Time-restricted feeding causes a shift in energy expenditure, favoring fat utilization during the fasting period, even with a normal diet.

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Food Entrainable Oscillator (FEO)

A biological timing mechanism that anticipates food availability, causing activity before meals.

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Anticipatory Activity

Increased activity in anticipation of a meal.

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Circadian rhythm

The biological process that regulates the sleep-wake cycle and other physiological processes over a 24-hour period. It is disrupted by no daily rhythm.

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SCN (Suprachiasmatic Nucleus)

A region of the brain that acts as the body's "master clock", although it is not the only part of the body controlling it.

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Jet lag

Disruption of the body's internal clock due to rapid travel across time zones.

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Shiftwork

Work that involves rotating shifts, which can disrupt the body's natural circadian rhythm leading to issues

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Clock genes (e.g., Per1/2/3)

Genes that regulate the circadian rhythm.

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FEO independent of SCN

FEO can function even when the SCN (master clock) is disabled; it exists outside the master control center.

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Simulated Shiftwork Schedule

Experimentally mimicking a shift work pattern to study its effects on the body, especially metabolic processes.

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Metabolic Rate

The speed at which your body burns calories at rest.

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Indirect Calorimeter

A device used to measure oxygen consumption and carbon dioxide production to estimate energy expenditure.

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Energy Expenditure During Sleep

The amount of calories burned while sleeping.

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Shift Work's Impact on Energy Expenditure

Shift work can disrupt natural sleep patterns, leading to lower energy expenditure during nighttime sleep, potentially contributing to weight gain.

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Circadian Clock and Metabolism

The biological clock (circadian rhythm) regulates metabolism, influencing how our body processes food and energy throughout the day.

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Irregular Eating and Metabolism

Eating at inconsistent times can disrupt the rhythm of metabolic processes in the body.

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Metabolic Dys-synchrony

Disruptions in metabolic processes due to irregular eating can lead to weight gain and reduced calorie burning.

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Late-Night Eating and Fat Accumulation

Eating before bedtime can hinder the body's transition to burning fat for energy, promoting fat storage.

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Night Eating Syndrome (NES)

A disorder where individuals experience excessive nighttime/late-night food cravings and consumption, despite having adequate food throughout the day.

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Glucose/Insulin Response in NES

In individuals with NES, insulin resistance at night can disrupt the normal balance of blood glucose regulation, possibly contributing to weight gain and metabolic complications.

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Time-Restricted Feeding (TRF)

A dietary approach that restricts eating to a specific time window each day, typically 8-12 hours.

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TRF and Recovery

Restricting IV feeding to daytime (TRF) in patients can accelerate recovery and lead to earlier hospital discharge.

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Study Notes

BSci 3230 Study Notes

  • These files are intended for BSci 3230 student use only in the class.
  • Students are not permitted to share these files or use them for other purposes, as some materials might be copyrighted.
  • The course covers Biological Clocks and Metabolism, including the obesity crisis, and clocks and metabolism in mice, humans, shift work, circadian misalignment, and gene expression in mouse adipose tissues.
  • Obesity "Epidemic" data for the USA in 2020 is mapped for various racial groups, showing different prevalence rates.
  • Light at night can disrupt the daily clock, causing metabolic disorders.
  • Shift work in humans can lead to obesity, diabetes, and cardiovascular disease due to physiological maladaptation.
  • A T28 Forced Desynchrony protocol was used to study circadian misalignment, showing significant changes in various metabolic factors (leptin, glucose insulin, arterial blood pressure, and sleep efficiency) when sleep/wake cycles and eating times are misaligned with normal cycles.
  • Circadian-controlled gene expression differs in various adipose tissues (liver, brown adipose tissue (BAT), inguinal white adipose tissue (iWAT), and epididymal (male gonadal) white adipose tissue (eWAT)).
  • Circadian patterns in liver, BAT, and iWAT are observed in 650 genes. Specific genes, like Cebp-a, Cebp-y, Lpl, Ppar-a, Pgc1-β, Stat5A, Enolase 3, etc., are implicated.
  • Findings on mice with mutant/knocked-out clock genes indicate that light, hormones (e.g., insulin), metabolic stimuli, the SCN (suprachiasmatic nucleus), peripheral tissues, clock genes and factors like PPARα, Rev-erba and SREBP1, influence metabolic regulation and resulting factors like glucose, cholesterol and triglyceride metabolism.
  • Genetic disruption of the clock (Bmal1) results in fat mice.
  • Studies in mouse models reveal that mutations in the "clock" gene lead to changes in energy intake, body weight, activity, and metabolic rate.
  • Meal timing and restricting food intake to specific periods can affect calorie intake and activity.
  • Mice show different responses when restricted to feeding during the "inactive phase" versus "active phase".
  • Time-restricted feeding (TRF) reduces appetite and increases fat oxidation but has no effect on energy expenditure.
  • Energy balance takes into account calories consumed (food quantity and timing), baseline metabolism (basal metabolic rate which is affected by weight, sex, age, physical activity and hormones), and exercise to ascertain if a person is in a state of weight gain or loss.
  • The human circadian rhythm affects metabolic rate at different phases of a 24/7 cycle.
  • Mobile apps like myCircadianClock can be used to track and understand human circadian rhythms, contributing to research.
  • Feeding time and duration are variable in humans
  • Restricting eating to 12 hours/day can reduce calorie intake by 20%.
  • Early TRF reduces appetite and increases fat oxidation but does not affect energy expenditure in humans.
  • Shift work can affect metabolic rate, and those who work shifts may have more energy expenditure during their inactive time.
  • Meal timing work in the Johnson Lab includes controlled lights, schedule, and metabolic measurements to study effects on metabolism in humans. Meal timing can impact lipid oxidation.
  • The phase of the liver's peripheral oscillator can be independently set and entrained by meal timing.
  • The hospital IV-feeding study shows that restricting feeding to daytime only accelerates recovery in subjects following HSCT (Hematopoietic stem cell transplantation).
  • Metabolic dys-synchrony from irregular eating or sleeping leads to weight gain because the body burns fewer calories during certain times. Eating before bedtime can delay the body from burning lipids and promote fat accumulation

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Description

This quiz explores the intricate relationship between metabolic processes and circadian rhythms, focusing on key topics such as insulin secretion, the role of glucagon, and energy expenditure in different conditions. Test your knowledge on how genetic disruption influences these mechanisms and the effects of feeding patterns on metabolism.

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