A&P: Metabolism and Nutrition (no Canada food guide)

• Energetics involves the study of energy flow and energy conversion

Metabolic Rate

• Metabolic rate measures 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

• Basal metabolic rate (BMR) is defined as the minimum resting energy expenditure of an awake, alert person
• BMR serves as a common benchmark for energetics studies
• BMR is measured when the body is in a quiet, resting, fasting condition
• On average, a person has a BMR of 70 Calories per hour, or 1,680 Calories per day
• Various factors, such as size, weight, and level of physical activity, can affect BMR
• Adequate food intake is necessary to support activities

Thermoregulation and Heat Balance

• Metabolic activities generate heat, which is a form of energy

• 40% of energy is used to form ATP

• 60% of energy is released as heat

• Temperature is how heat can be measured and expressed as a calorie

• A calorie is the amount of energy required to raise 1 gram of water by 1°C

• A kilocalorie (kcal) or Calorie (Cal) equals 1000 calories

• Despite fluctuations in environmental temperatures, homeostatic mechanisms maintain a normal range for internal body temperature

• Core temperature is 37°C or 98.6°F, while shell temperature is 1-6°C lower

• Maintaining proper temperature is important for function and structure

Mechanisms of Heat Transfer

• Ways that heat transfers: radiation, convection, evaporation, and conduction
• Radiation refers to heat energy transfer as infrared radiation; an example is heat from the sun
• Over 50% of body heat loss indoors occurs via radiation
• Convection is the result of heat loss due to air movement
• Warmer air rises away from the body and is replaced by cooler air
• About 15% of heat loss indoors is due to convection
• Evaporation cools the skin as water changes from liquid to vapor, absorbing 0.58 Cal per gram of water
• Insensible perspiration from alveoli and skin accounts for about 20-25 mL per hour (relatively constant)
• About 20% of body's heat loss indoors is insensible perspiration
• Sensible perspiration from sweat glands can excrete up to 2-4 liters per hour
• Conduction is the direct transfer of energy through physical contact
• Conduction is generally not an effective mechanism for gaining or losing heat
• Blood vessels of the dermis constrict when core temperature declines
• Reducing heat loss by radiation and convection
• Contraction of arrector pili also reduces heat loss by radiation and convection
• Release of thyroid hormones, epinephrine, and norepinephrine increases cellular metabolism which generates heat
• Shivering generates heat
• If core body temperature is too high, skin blood vessels dilate and heat loss occurs through radiation and convection
• Sweat glands are stimulated for heat loss through evaporation
• Metabolic rate decreases, which generates less heat

Appetite Regulation

• Appetite regulation involves two areas of the hypothalamus with opposite effects; stimulating one inhibits the other
• Feeding center regulates hunger
• Satiety center regulates food satisfaction
• Social factors, psychological pressures, and dietary habits affect the areas.
• Regulation of appetite occurs on short-term and long-term levels

Short-Term Appetite Regulation

• The satiety center is stimulated by Elevated blood glucose levels, Hormones of digestive tract (such as CCK), and Stretching of digestive tract wall
• The feeding center is stimulated by Neurotransmitters (e.g., neuropeptide Y, or NPY, from hypothalamus) and Ghrelin (hormone secreted by gastric mucosa when stomach is empty)

Long-Term Appetite Regulation

• Leptin stimulates the satiety center. Leptin is a peptide hormone secreted by adipocytes
• Leptin stimulates the satiety center and suppresses appetite
• Effects of Leptin are gradual

Metabolic Syndrome

• A group of conditions occurring together increasing the risk of cardiovascular disease, stroke, and type II diabetes.
• Metabolic syndrome is defined by central obesity is present and two of the following:
• Hypertension: systolic > 130 or diastolic > 85 mmHg
• Increased triglycerides
• Reduced HDL cholesterol
• Raised fasting blood glucose
• Epidemiology estimates is at ~25% of the adult population worldwide
• Risk factors include Sedentary lifestyle, Poor diet, High BMI, Genetics, Smoking, Socioeconomic status, and Education

Nutrition Basics

• Nutrition is the science of how food and drink affect human health
• Nutrients are essential for energy, growth, and bodily functions
• Non-nutrients do not provide energy but have health benefits such as fibre and phytochemicals
• Essential nutrients need to be acquired from the diet

Macronutrients

• Macronutrients includes carbohydrates, proteins, lipids are the nutritive components of food
• They provide the body with energy; macronutrients are also known as "macros"
• Macronutrients: carbohydrates, proteins, and lipids

Micronutrients

• Micronutrients are essential nutrients that humans require in small amounts
• Vitamins and minerals are micronutrients
• No healthy diet excludes or seriously restricts a macronutrient; the percentages of macronutrients are:
  • 45%-65% from carbohydrates
  • 25%-35% from fats
  • 10%-35% from proteins
• Amount of macronutrients will shift depending on certain goals of the individual

Carbohydrates

• Carbohydrates are nutrients that serve as the main source of body energy
• Carbohydrates supply four calories of body energy per gram of food and should make up 45-65% of your diet
• This macronutrient includes sugars, starches, and fiber
• There are two types of carbohydrates: simple and complex
• Simple carbohydrates are sugars that enter the bloodstream rapidly and provide energy quickly, but provides only calories with few vitamins and minerals
• Complex carbohydrates includes are starches and fibers; complex carbs provide vitamins, minerals, and fiber, the part of grains/plants that cannot be digested
• Complex carbohydrates provide more nutrients the body compared to simple carbs

Fiber

• The part of grains and plant foods that cannot be digested
• Two types of fiber: soluble and insoluble
• Insoluble fiber helps prevent constipation and other intestinal problems by binding with water, which reduces ones risk of colon cancer
• Soluble fiber helps to reduce blood cholesterol and one's risk of heart disease

Lipids (Fats)

• A nutrient that provides energy and helps the body store and use vitamins
• Fats supply nine calories of energy per gram of food and should make up 25-35% of one's diet and helps maintain body heat
• Fats builds brain cells and nerve tissues
• This includes saturated fat, unsaturated fat, and trans fat
• Saturated fats are often solid at room temperature and are found in dairy products, solid vegetable fat, meat, and poultry
• The may contribute to the level of LDL cholesterol in a person's blood
• Unsaturated fats include monounsaturated fats (MUFAs) and polyunsaturated fats (PUFAs) and are predomiantly found in plants
• Considered beneficial
• Can improve blood cholesterol levels and play a number of other beneficial roles

Unsaturated Fats

• Monounsaturated fats are found in olive, peanut, and canola oils
• Avocados, Nuts, pumpkin, and sesame seeds.
• Polyunsaturated fats are found in sunflower, corn, soybean, and flaxseed oils, walnuts, flax seeds, and fish
• Omega-3 fats are an important type of essential polyunsaturated fat
• Eating fish 2-3 times a week, flax seeds, walnuts, and canola or soybean oil can help one gain omega 3 fats
• Higher blood omega-3 fats are associated with lower risk of premature death among older adults
• Trans fats are created by hydrogenating vegetable oils, which makes them more stable and less likely to become rancid
• This process also converts the oil into a solid; partially hydrogenated oils can withstand repeated heating without breaking down
• Trans fats are naturally found in beef fat and dairy fat in small amounts.
• Trans fats are worse for the heart and rest of the body because;
• Raise bad LDL and lower good HDL
• Contribute to insulin resistance
• Limit to 1% of daily calories (less than 2.2 g maximum
• Most people do not eat enough unsaturated fats.
• Have 8-10% of the diet being polyunsaturated to help lower risk of heart disease

Proteins

• Nutrient needed for growth, and builds and repairs body tissues
• Proteins supply four calories of energy per gram of food and should make up 10-30% of one's diet
• Two different kinds of proteins: complete and incomplete proteins
• The building blocks that make up proteins are amino acids, the body needs 20 amino acids to function properly
• Nine amino acids that the body cannot produce are essential amino acids, while the body can only produce 11
• Complete protein contains all of the essential amino acids (meat, fish, and eggs)
• Vegetarian source of complete protein are; quinoa, soybean, buckwheat, spirulina, rice and beans with hummus.
• One should have a wide variety of plant foods such as legumes, lentils, nuts, seeds and whole grains on a daily basis to stay healthy
• Protein deficiency is very rare, a vegetarian diet can easily fulfill needed demands

Micronutrients

• Needed by the body in smaller amounts to maintain normal health and prevent various diseases
• Micronutrients do not provide energy
• There are Vitamins such as water and fat souluable and Trace Minerals
• Organic compounds present in different food that help various biochemical processes
• Important for growth and overall health that all can be acquired through small amounts

Water-Soluble Vitamins

• Important of Vitiamin B & C to prevent specific diseases
• Vitiamin B- Pantothenic Acid, Niacin, Riboflavin, Thaimin, Pyridoxine Folate, Cobalamin
• Fat-Soluble Vitamins: Includes Vitamin A, D, E and K that are stored in the body

Vitamin Funciton in Body

• Act as hormones (vitamin D), act as antioxidants (vitamin E), mediators of signaling and regulators of tissue (vitaminA)
• Functioning in blood clotting and for bone growing using vitamin K + Acting as a precursors for enzymes to become catalysts
• Minerals are trace elements and divided into Macro (>100mg) Micro (<100gm)

Minerals and Trace Elements

• Macrominerals are calcium, phosphorous etc and Microminerals are Iodine, copper, zinc
• The minerals help with chemical Rx etc as Co factors
• Act as electrolytes, helps our structures - signals our cells
• RDA / AI is needed for our bodies to process foods and for our tissue stores
• Deficiancy is a small problem that mostly happens to older adults with toxicity and is not well understood

Key Deficiancies

• The key deficiancies of key nutrients are; D, Iron, Magnesium, iodine etc.

Canada food guide (2019 version)

• To focus on more fruits/ veggies ~50 % with a drink to be water + Grain/ Proteins/ based -25%