A&P: Metabolism and Nutrition

Energetics

• Energetics is the study of energy flow and energy conversion.

Metabolic Rate

• Metabolic rate is the overall rate at which metabolic reactions use energy.
• Some energy is used to make ATP and some is lost as heat.

Basal Metabolic Rate (BMR)

• BMR is a common benchmark for energetics studies.
• BMR is defined as the minimum resting energy expenditure of an awake, alert person.
• BMR is measured when the body is in a quiet, resting, fasting condition.
• An average person has a BMR of 70 Calories per hour which equates to 1680 Calories per day.
• Factors such as size, weight, and level of physical activity can affect BMR.
• Adequate food intake is essential to support activities.

Thermoregulation

• Metabolic activities generate heat, a form of energy.
• 40% of energy is used to form ATP, and 60% is released as heat.
• Temperature can be expressed as a calorie.
• The quantity of energy needed to raise 1 gram of water by 1°C is called a calorie (cal).
• A kilocalorie (kcal) or Calorie (Cal) is 1000 calories.
• Homeostatic mechanisms maintain a normal range for internal body temperature despite fluctuations in environmental temperatures.
• Core temperature is consistently 37°C or 98.6°F.
• Shell temperature is consistently 1-6°C lower than core temperature.
• Maintaining proper temperature is essential for proper bodily function and structure.

Mechanisms of Heat Transfer

• There are four main mechanisms of heat transfer: radiation, convection, evaporation, and conduction.
• Radiation is heat energy transfer as infrared radiation.
• An example of radiation is heat from the sun.
• More than 50% of body heat loss indoors occurs via radiation.
• Convection results in heat loss due to air movement.
• Warmer air rises from the body and is replaced by cooler air in convection.
• Convection accounts for about 15% of the body's heat loss indoors.
• Water changing from liquid to vapor absorbs 0.58 Cal per gram during evaporation.
• Evaporation cools the surface of the skin.
• Insensible perspiration from alveoli and skin accounts for about 20-25 mL per hour and about 20% of body's heat loss indoors.
• Sensible perspiration from sweat glands can excrete up to 2-4 liters per hour.
• Conduction is a direct transfer of energy through physical contact.
• Conduction is generally not an effective mechanism of gaining or losing heat.

Core Temperature Decline

• If core temperature declines, blood vessels of the dermis constrict, reducing heat loss by radiation and convection.
• Contraction of arrector pili reduces heat loss by radiation and convection when core temperature declines.
• Release of thyroid hormones, epinephrine, and norepinephrine increases cellular metabolism and generates heat when core temperature declines.
• Shivering generates heat when core temperature declines.

Core body temperature too high

• If core body temperature is too high, skin blood vessels dilate, which increases heat loss through radiation and convection.
• Sweat glands are stimulated to increase heat loss through evaporation when core body temperature is too high.
• Elevated core body temperature leads to a decreased metabolic rate, which generates less heat.

Appetite Regulation

• Appetite regulation involves two areas of the hypothalamus that have opposite effects; stimulating one inhibits the other.
• The two areas of the hypothalamus are the feeding center, involved with hunger, and the satiety center, involved with food satisfaction.
• Multiple social and psychological factors, including dietary habits, can affect these areas.
• Appetite can be regulated through short-term and long-term regulations.

Short-Term Regulation of Appetite

• Stimulation of the satiety center results from elevated blood glucose levels, hormones of the digestive tract, such as CCK, and stretching of digestive tract wall.
• Neurotransmitters, such as neuropeptide Y, and ghrelin, secreted by the gastric mucosa, stimulate the feeding center when the stomach is empty.

Long-Term Regulation of Appetite

• Leptin stimulates the satiety center.
• Leptin is a peptide hormone secreted by adipocytes.

Metabolic Syndrome

• Metabolic syndrome is a cluster of conditions that occur together, increasing the risk of cardiovascular disease, stroke, and type II diabetes.
• Metabolic syndrome is defined by central obesity, plus any two of the following: hypertension, increased triglycerides, reduced HDL cholesterol, and raised fasting blood glucose.
• Epidemiology statistics show that Metabolic syndrome affects approximately 25% of the adult population worldwide.
• Risk factors for metabolic syndrome include sedentary lifestyle, poor diet, high BMI, genetics, smoking, socioeconomic status, and low levels of education.

The Importance of Nutrition

• After smoking and alcohol, diet has the most significant effect on long-term health.
• Important modifiable risk factors include sleep and physical activity.
• Many chronic diseases are directly influenced by diet, including hypertension, cardiovascular disease, cerebrovascular disease, kidney disease, diabetes, obesity, and cancer.
• Nutrition is defined as the science of how food and drink affect human health.
• Nutrients are essential for energy, growth, and bodily functions.
• Non-nutrients, such as fiber, which aids digestion, and phytochemicals, which may reduce disease risk, do not provide energy but have health benefits.
• Essential nutrients are acquired from diet; including essential fatty acids (omega-3 and omega-6) and essential amino acids.

Nutrients

• Macronutrients are the nutritive components of food that provide the body with energy, these are also known as macros.
• The three macronutrients are carbohydrates, proteins, and lipids.
• Micronutrients are essential nutrients that humans require in small amounts.
• Vitamins and minerals are what micronutrients consist of.

Macronutrients

• All three macronutrients (carbohydrates, lipids, and protein) and fats are needed for proper health.
• No healthy diet should exclude or seriously restrict any macronutrient.
• A certain amount of daily caloric intake should come from each group.
• 45%-65% of daily caloric intake should be from carbohydrates
• 25%-35% from fats
• 10%-35% from proteins
• Daily caloric amounts can shift depending on specific goals of the individual.

Carbohydrates

• A carbohydrate is a nutrient and the main source of energy for the body.
• Carbohydrates supply four calories of energy per gram of food.
• Carbohydrates should make up 45-65% of daily caloric intake.
• Sugars, starches, and fiber are what carbs inlcude.
• The two types of carbohydrates are simple and complex.
• Simple carbohydrates are sugars that enter the bloodstream rapidly and provide energy quickly.
• Simple carbohydrates, such as vegetables, fruits, milk, are sources of sugars that provide calories but few vitamins and minerals.
• Complex carbohydrates are starches and fibers.
• Starch is a food substance made and stored in most plants.
• Fiber is the part of grains and plants that cannot be digested.
• Complex carbs are found in foods such as breads, legumes, rice, pasta, and starchy vegetables.
• Complex carbohydrates are better for the body than simple carbohydrates.
• Complex carbs should make up the bulk of carb intake, while simple carbs should be eaten in moderation.
• Fiber is the part of grains and plant foods that cannot be digested.
• The two types of fiber are soluble and insoluble.
• Insoluble fiber helps reduce the risk of colon cancer by preventing constipation and other intestinal problems by binding with water.
• Soluble fiber helps reduce risks of heart disease by helping to reduce cholesterol levels.

Lipids

• Lipids, or simply known as fats, are a nutrient that provides energy and helps the body store and use vitamins.
• Fats supply nine calories of energy per gram of food.
• Fats should make up 25-35% of your diet.
• Fats are needed to maintain body heat, maintain an energy reserve, and build brain cells and nerve tissues.
• The types of fats include saturated fats, unsaturated fats, and trans fats.
• A type of fat found in dairy products, solid vegetable fat, meat, and poultry is defined as a saturated fat.
• Saturated fats are most often solid at room temperature.
• Butter, palm and coconut oils, cheese, and red meat have high amounts of saturated fat.
• Saturated fats may contribute to high level of LDL cholesterol.
• Unsaturated fats are liquid at room temperature.
• Unsaturated fats are considered beneficial due to their properties of improving blood cholesterol levels.
• Unsaturated fats can be found in foods from plants, such as vegetable oils, nuts, and seeds.
• Two types of unsaturated fats include monounsaturated fats (MUFAs) and polyunsaturated fats (PUFAs).
• Monounsaturated fats are found in high concentrations in olive, peanut, and canola oils; avocados; nuts such as almonds, hazelnuts, and pecans; seeds such as pumpkin and sesame seeds.
• Polyunsaturated fats are found in high concentrations in sunflower, corn, soybean, and flaxseed oils; walnuts; flax seeds; and fish.
• Omega-3 fats are an important type of essential polyunsaturated fat.
• Consuming fish 2-3 times a week is a great way to get omega-3 fats.
• Good plant sources for omega-3 fats include flax seeds, walnuts, and canola or soybean oil.
• Higher blood omega-3 fats are associated with lower risk of premature death among older adults, according to a study by Harvard School of Public Health faculty.
• Trans fats are created by hydrogenating vegetable oils, which makes them more stable and less likely to become rancid.
• Partially hydrogenated oils withstand repeated heating without breaking down, making them ideal for frying fast foods.
• Trans fats are naturally found in beef fat and dairy fat in small amounts.
• Trans fats are the worst type of fat because they raise bad LDL, lower good HDL, and contribute to insulin resistance.
• Even small amounts of trans-fats can have harmful health effects.
• By consuming an additional 2 percent of calories from trans fat consumed daily, the risk of coronary heart disease increases by 23 percent.
• Consumption of trans-fats should be limited to less than 1% of daily calories, such as < 2.2 g maximum.
• A tip for choosing the right fats is to consume enough healthful unsaturated fats, as most people do not.
• The American Heart Association suggests that 8-10% of daily calories should come from polyunsaturated fats.
• Consuming more polyunsaturated fat (up to 15 percent of daily calories) in place of saturated fat can lower heart disease risk.
• Saturated fats should make up less than 10% of daily calories.
• Trans fats should be limited to less than 1% of daily calories.

Proteins

• A nutrient that helps build and repair body tissues is known as a protein.
• Proteins are needed to regulate body processes and to supply energy.
• Proteins supply four calories of energy per gram of food.
• Proteins should make up 10-30% of your diet.
• The two different kinds of proteins are complete proteins and incomplete proteins.
• Amino acids are the building blocks that make up proteins.
• The body needs 20 amino acids to function properly.
• Only 11 of these amino acids can be produced by the body.
• Nine amino acids are considered essential amino acids that the body cannot produce.
• A protein that contains all of the essential amino acids is a complete protein.
• Examples of complete proteins are meat, fish, poultry, milk, yogurt, and eggs.
• Vegetarian sources of complete proteins include quinoa, soybean (tofu, tempeh, edamame), buckwheat, spirulina, hemp seeds, chia seeds, nutritional yeast, rice and beans in combination, pita and hummus in combination.
• It was once thought that every meal needed to contain all essential amino acids, and vegetarians would have to combine various proteins to source these in their diets.
• It is more evident now that as long as an individual is eating a well balanced diet, they get enough essential amino acids throughout the day.
• Vegetarians should strive for a wide variety of plant foods such as legumes, lentils, nuts, seeds and whole grains on a daily basis.
• Protein deficiency is very rare, and a vegetarian diet can meet all demands, so long as there is a little attentiveness.

Micronutrients

• Micronutrients are nutrients needed by the body in small amounts.
• Vitamins, minerals and trace minerals are all types of micro nutrients
• Micronutirents, rather than providing energy, help to mantain normal health and prevent a variety of diseases.
• Vitamins are organic compounds found in limited quantities in foods.
• Vitamins help in the cell in a variety of biochemical processes.
• Being essential components, Vitamins are important to maintain good health and growth
• Vitamins are non caloric, or do not provide calories as an alternative name.
• Vitamins include fat-soluble vitamins, such as, A, D, E, and K, that the body retains and stores.
• Water soluable vitamins include Ascorbic acid or vitamin C, Thiamin or vitamin B1, Riboflavin or vitamin B2, Niacin or vitamin B3, Pyridoxine or vitamin B6, Biotin or vitamin B7, Pantothenic acid or vitamin B5, Folate or vitamin B9, Cobalamin or vitamin B12.
• Acting as hormones such as Vitamin D, Vitamins can assist bodily functions.
• As demonstrated in Vitamin E, acting as antioxidant, is another vitamin function
• Facilitation of cell signaling vitamins and regulators of cell and tissue process and differentiation (vitamin A) are anothe rvitman dunction
• Also functions such as aid in blood clotting are performed such as with vitamin K along with vitamin precursors to catalysts.

Minerals and trace elements

• Minerals and trace elements contain macroninerals ( > 100 mg) and micromineral ( <100 mg) per day.
• Macroninerals include: Calcium, Phosphorous, Sodium, Potassium, Chloride, Magnesium.
• Microminerals include: Iron, Iodine, Copper, Manganese, Zinc, Cobalit, Molybdenum, Selenium, Fluoride. Chormium, Silicon.
• Minerals and trace elements include assisting as cofactors in the chemical interactions; Zn, Mg, Fe, Cu, Mn.
• Also functions such as aid in electrolytes, structual aid, transport proteins.
• There are RDAs and AIs that help prevent disease.
• Deficiences are not a prominent problem in Canada because there is great access to nutrients.
• Overdoing minerals can cause toxicty and have side effects such as the UL effect.

Micronutrient Deficiencies

• Vitamin D is the most common nutrient deficiency in Canada.
• Examples of further dificienies include, Iron, Magnesium, Iodine, Vitamin A, Vitamin B12, Calcium.

Canada’s Food Guide

• New as of 2019 Canada's food guide has three major groups.
• These groups include fruits, vegetables, whole grains and proteins.
• Water is now considered the recommended drink over Dairy.
• In following Canada's guide it sets up that a intake should be made of roughly fruits,vegetables, whole grains, and proteins.
• Positives to the Canada food guide are that it is based on comprehnsive science, clear cut, a reudction of dairy, and emphasis of foods over processed.
• In this way it promotes healhier habits such as cooking and eating in community but provides a comprehensive approach.
• The website is very helpful
• Canada's food guide is also promotes eating to be less restrive.
• Negatives of the guide are that it may not fit all populations such as cultural. vulnerble, etc.
• Also unrealisitic for specific groups such as those with food.

Nutrition information

• The red flags: Information being sold, negative advice, no citation, fake research, or logic with no evidence.
• Legit informtaion includes research and not being for personal gain