Identify the digestive enzymes responsible for the digestion of carbohydrates proteins and lipids.

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Lab 5 Digestion and Metabolism Sum20




1. Calculate BMI and estimate Basal Metabolic Rate.

2. Complete a dietary and activity record to estimate weight loss/gain and to guide suggestions for improving diet and activity.

3. Identify the digestive enzymes responsible for the digestion of carbohydrates proteins and lipids.

4. Trace the pathway food travels through the digestive tract and describe processes of digestion, secretion, motility and absorption.

5. Describe the different nutrient classes and list the calorie content per gram for each.

PART ONE: METABOLISM LAB: Nutrient Assessment, BMI, and Body Composition


Metabolism is the sum total of all chemical reactions that are occurring in the body. It is subdivided into catabolism and anabolism. Catabolic reactions are those reactions that break down or hydrolyze large molecules into smaller subunits. Anabolic reactions are those that build large molecules from smaller ones. Catabolic reactions involve the release of energy (exergonic) while anabolic reactions require the input of energy (endergonic).

The balance between anabolism and catabolism is influenced by the intake of energy from foodstuffs and is regulated largely by the endocrine system. When more food energy is taken in than is used, anabolism dominates and the body gains weight. When less food energy is consumed than is used, catabolism dominates to release energy from stored energy molecules and the body loses weight. When the body is neither gaining nor losing weight, anabolism and catabolism are in balance.

Body mass index, or BMI, is the measurement of choice for many physicians and researchers studying obesity. BMI uses a mathematical formula that takes into account both a person’s height and weight. BMI equals a person’s weight in kilograms divided by their height in meters squared. (BMI=kg/m2).

Note: 1 inch = 2.54 cm. 12 inches = 1 foot. 1 meter = 100 cm. 1 kilogram = 2.2 lbs.

Record weight in pounds (lbs) and convert to kilograms (kg). Show work.

Record height in inches (in) and convert to meters (m). Show work.

Calculate BMI. Show work.

Weight ______ (Lbs) Weight ______ (Kg)

Height ______(inches) Height ______(m) (Height)2 _________________ (m2)

Calculate your BMI: Weight (Kg) / (Height (m))2 = ________________(Kg / m2)


People with apple-shaped bodies (more fat around the abdominal area) seem to develop cardiovascular disease, hypertension, and diabetes mellitus at a higher rate than those with pear-shaped bodies (more fat in the hips, buttocks, and thighs).

To determine if you have a healthy waist to hip ratio, use a measuring tape to measure the circumference of your hips at the widest part of your buttocks. Then measure your waist at the smaller circumference of your natural waist, usually just above the belly button.

1. Stand and measure your waist at the navel. __________ cm

2. Measure your hips at the greatest circumference around the buttocks. __________ cm

3. Divide the waist circumference by the hip circumference. Ratio: ___________

For women, the waist-to-hip ratio should come out to no more than 0.8. Men have a little more wiggle room: a healthy waist-to-hip ratio for men is 0.95. This means, if your belly has bulged out enough to catch up to the size of your hips, you should start worrying about your heart. Abdominal fat leads to changes in hormone levels contributing to inflammation and leading to clogged arteries.


Both the chemical energy consumed in foods and the metabolic energy expended by cells are measured in kilocalories (kcal) or Calories (C). The major source of food calories are carbohydrates, lipids, and proteins. For one gram, carbohydrates yield 4 kcal, fat 9 kcal, and protein 4 kcal. A well-balanced diet consists of about 45-65 % carbohydrates, 20-35 % fat, and 10-35 % protein.

Keep track of your activity and diet as follows:

1. Keep track of daily activity (e.g. jogging 45 min or walked to school 20 min). Record all activity in Table 1 below or create your own table if you prefer.

2. Complete a 1-day dietary record. (For better accuracy, you could record over 3 consecutive days, including one weekend day, and take an average.)

3. Record all foods and fluids consumed in Table 2 or create your own table. Estimate food quantities by weight (grams) and fluids by volume (milliliters).

4. Read labels or look up the estimated calories for each food in your record. The caloric values can also be obtained from websites (e.g. or apps (e.g.

5. Note the time each food or fluid was consumed as well as comments to help with analysis of dietary habits (e.g. 1pm lunch or midnight snacking – stressed studying for exam).

Table 1. Activity Record

Date: ________________

Time Type of Activity Comments

Table 2. Dietary Record

Date: ________________

Time Food Description Carb (g) Fat (g) Protein (g) Calories
Total Calories Consumed =



The total energy expended each day includes the energy consumed at rest and during physical activity. The Basal Metabolic Rate (BMR) is a measure of the energy required to maintain the body.

Determine your BMR using the Harris-Benedict formula based on total body weight.
The Harris Benedict equation is a calorie formula using the factors of height, weight, age, and gender to determine basal metabolic rate. This makes it more accurate than determining calorie needs based on total body weight alone. The only variable it does not take into consideration is lean body mass. This equation will be accurate for most, but will underestimate caloric needs in those who are extremely muscular and will overestimate caloric needs, in those who are extremely obese.

Men: BMR = 66 + (13.7 x Weight in kg) + (5 x Height in cm) – (6.8 x Age in years)

Women: BMR = 655 + (9.6 x Weight in kg) + (1.8 x Height in cm) – (4.7 x Age in years)

Calculate BMR:

(Show work)

Take into account your daily activity from Table 1 and use this to Estimate your Energy Expenditure. Multiply your calculated BMR (from above) by the appropriate activity multiplier (below).

Activity Multiplier:

Sedentary = BMR X 1.2 (lay in bed all day; no exercise)

Lightly active = BMR X 1.375 (normal daily activity no exercise/sports)

Moderately active = BMR X 1.55 (normal daily activity 1 hr exercise/sports)

Very active = BMR X 1.725 (normal daily activity 2 hrs hard exercise/sports)

Extremely active = BMR X 1.9 (normal daily activity 4 hrs rigorous athletic training)

Calculate (BMR x Activity Multiplier):

(Show work)

Total Calories

Expended = ________________________

PART TWO: DIGESTIVE PHYSIOLOGY LAB: Chemical Digestion of Nutrients

When we eat food, we are ingesting a combination of nutrients. These nutrients are in the form of macromolecules such as carbohydrates, proteins, and lipids. In order for our body to be able to use these important nutrients, they must be broken down into smaller pieces that can be absorbed into our cells. Only when digested into simple monomeric form can food be absorbed.

The process of digestion in humans involves two very different mechanisms: mechanical digestion and enzymatic or chemical digestion. Mechanical digestion involves physically breaking food into smaller pieces, in order to increase the surface area for enzymes to chemically digest food molecules. Mechanical and chemical digestion take place primarily in the organs listed below.

1. List some examples of mechanical digestion for each organ in the table below.

2. Name the enzymes that carry out chemical digestion in each of the organs listed below.

Table 3. Mechanical and Chemical Digestion


Mechanical Digestion

List examples of mechanical digestion

Chemical Digestion

Name the enzyme that carries out this chemical digestion

Oral Cavity

Starch (___________________________(Maltose


Proteins (____________________(Polypeptides

Small intestine

Starch (________________________ (Maltose

Disaccharides (________________(Monosaccharides

Protein (_________________________(Polypeptides

Polypeptides (____________________ (Amino acids

Fats ( _________________ ( Fatty acids and glycerol

Nucleic acids (____________________ ( nucleotides

DIGESTION: Analysis of a FOOD

Choose a food from Table 2 of your Dietary Record and record the name of the food.

Beginning with this food entering the mouth, and ending with exit of waste from the body, describe the specific processes of Digestion, Secretion and Absorption that take place as this food travels through each organ of the digestive tract. Include contributions of accessory digestive organs.


1. Answer all questions, complete all tables, and perform all calculations.

2. Determine the total Calories expended (Energy Output) during your dietary experiment.

3. Determine the total Calories consumed (Energy Intake) during your dietary experiment.

4. Compare the Calories expended with the Calories consumed. Is there a net gain or loss?

5. Since there are 3,500 kcal/ pound, and if your 1-day average caloric intake was representative, what would be the expected weight gain or loss in pounds over a 30-day period? Over one year? Discuss your results.

6. Study your dietary and activity record. Write a thoughtful and detailed analysis with at least four specific suggestions for improving your diet and activity.

7. Name a specific food from your Dietary Record Table 2. Then trace the pathway (list organs) through the digestive tract from mouth to anus this food passes through. Describe the specific processes of Digestion, Secretion, and Absorption that occur as this food travels through each organ of the digestive tract.

Note: Write answers directly on this lab worksheet or create a new Word document (or PDF) that

addresses the 7 areas and includes all questions, tables, and calculations.

For this article summary research

Any topic of interest related to pathophysiology (disease). We have mainly focused on normal physiology, because in order to understand disease, you first need to know how the body works under normal conditions. In this assignment, explore any type of pathophysiology of interest. Below are some examples of terminology and health-related descriptions for disease or illness that you may encounter as part of pathophysiology:

· A disease is a pathophysiological response to internal or external factors.

· A disorder is a disruption to regular bodily structure and function.

· A syndrome is a collection of signs and symptoms associated with a specific cause.

· A condition is an abnormal state of health that interferes with normal feelings of wellbeing.

In 5-10 sentences summarize the main points of the article in your own words. In a separate paragraph discuss which specific organ systems are involved and briefly sum up for the class how the disease state (pathophysiology) in the body differs from the non-disease state (normal physiology). Finally, comment on 2 classmate article posts.

· Includes title and link to original article

· Concise, clearly written summary paragraph of article in own words

· Names organ systems involved and states how disease state differs from normal physiology ~5 sentences