NutriSci 10 Midterm 1 - Gregory Aponte

Social, Biological, Physical, Psychological aka Nutritional Sciences

The study of nutrition requires the integration of which sciences?

Forming structures, providing energy

The two functions of nutrients are:

forming structures (nutrients)

- Most of the weight of the body is due to water, fat and protein.

- Nutrients help to form and maintain the shape and structure of the body.

- Proteins form ligaments and tendons that hold bones together and attach muscles to bones.

- At the cellular level, lipids and proteins make up the membranes that surround cells.

providing energy (nutrients)

- Working together, macronutrients and micronutrients help the body stay healthy

- biochemical reactions in the body help to release the energy contained in carbohydrates, fats, and proteins

- energy is used to maintain body functions and fuel physical work

- if more energy is consumed than is needed, over time body weight will increase

healthy diet

provides provides the right amount of energy to keep weight in the desirable range; the proper types and balance of carbohydrates, proteins, and fats; plenty of water; and sufficient but not excessive amounts of essential vitamins and minerals

3 Functional Categories of Nutrients

- Those that provide energy (measured in kcal)

- those that are important for growth and development (and later maintenance)

- those that keep body functions running smoothly

*there tends to be overlap among these functions in nutrients

Energy yielding nutrients and water

Functional category of nutrients that makes up a major portion of mosts foods

Essential Nutrients

- specific biological function

- removal from the diet leads to a decline in human biological function, such as the normal functions of the blood cells or nervous system

- returning the omitted substance to the diet before permanent damage restores to normal those aspects of human biological function impaired by its absence

Composition of the Human Body

- 62% water

- 16% protein

- 16% fat

- 6% minerals, carbs, and other substances

Carbohydrates

the body's main source of energy and therefore should be the major part of total daily intake

Simple Carbs

examples: sugar, honey

Complex Carbs

- preferred over simple carbs as they are more nutritious yet have fewer calories per gram compared to fat and cause fewer problems with overeating

- also preferred over simple carbs by diabetics because they offer more glucose control

- examples: grains, beans, peas, potatoes

fiber

- material that gives plants texture and support

- primarily made up of carbs, however does not have a lot of calories and is usually not broken down by the body for energy

insoluble fiber

- does not dissolve in water because of high amounts of cellulose

- found in: bran of grains, pulp of fruit, skin of vegetables

- speeds up transit of foods through the digestive tract

soluble fiber

- type of fiber that dissolves in water

- found in: variety of fruits and vegetables such as apples, oatmeal, oat bran, rye flour, and dried beans

- can lower blood cholesterol levels by attaching itself to the cholesterol so that it can be eliminated by the body, which then prevents cholesterol from recirculating and being reabsorbed into the bloodstream

fat

supplies energy and transports nutrients

Omega-3 and Omega-6 fatty acids

- the two families of fatty acids considered essential for the body (essential fatty acids)

- required by the body to function normally

omega-3 fatty acids

- recommended to help reduce risk of cardiovascular diseases, and cancer, can help alleviate many chronic diseases

- examples: canola oil, flaxseed oil, cold water fish, fish oil

omega-6 fatty acids

examples: primrose, black currant seed oil

protein

- supplies amino acids to build and maintain healthy body tissue

- necessary for all aspects of metabolism and growth

9 amino acids

number of essential amino acids

essential amino acids

- 12 manufactured by the body, 8 must be provided by the diet

- animal product (milk and eggs), in addition to plant product (protein complementation) must be combined to provide all necessary protein components

vitamins

organic substances present in food and are required by the body in small amount for regulation of metabolism and maintenance for normal growth and functioning

most commonly known vitamins

A, B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), B9 (folic acid), B12 (cobalamin), C (ascorbic acid), D, E, and K

Vitamins B and C

- water soluble vitamins, meaning that excess amounts are excreted in the urine

Vitamins A, D, E, and K

fat soluble, meaning that they will be stored in fat

minerals

- important component of muscles, tissues, and bones

- important components of hormones, oxygen transport, and enzyme systems

major minerals

minerals that the body needs in large amounts, such as calcium, phosphorous, magnesium, sodium, potassium, sulfur, and chloride

trace minerals

minerals only needed in small amounts that participate in most chemical reactions through the body, such as iron, zinc, copper, iodine, and manganese

water

helps to regulate body temperature, transport nutrients and minerals to cells, rids the body of waste materials, essential to all life processes

nutrient density

- a measure of the nutrient a food provides compared to its energy content

- nutrient dense diet = healthy diet

- example: broccoli is more nutrient dense than french fries

metabolism

- the set of life-sustaining chemical transformations within the cells of living organisms

- enzyme-catalyzed reactions (anabolism and catabolism) allow organisms to grow and reproduce, maintain their structures, and respond to their environments

anabolism

- uses energy to construct components of cells

- the set of metabolic pathways that construct molecules from smaller units

- these processes require energy

catabolism

- breaks down organic matter, for example to harvest energy

- the set of metabolic pathways that breaks down molecules into smaller units that are either oxidized to release energy, or used in anabolic reactions

cellular respiration

refers to the biochemical pathway by which cells release energy from the chemical bonds of food molecules and provide that energy for the essential processes of life

nucleus

DNA information is translated out of the ____ to the endoplasmic reticulum

smooth endoplasmic reticulum

deals with lipid metabolism

rough endoplasmic reticulum

deals with protein synthesis through ribosomes (rough), which bind mRNA and tRNA to make proteins

lysosome

breaks down, recycles, and or expels waste

mitochondria

- where everything we eat goes

- participates in the chemical processes that transfer energy from the chemical bonds of nutrient molecules to newly created ATP molecules

- where the citric acid cycle occurs

membranes and walls

these create segregation, and therefore gradients with the help of fluid

entropy and disorder

work is required to produce order out of disorder, so energy must be used for production of a highly ordered store

oxidation

the loss of electrons or an increase in oxidation state by a molecule, atom, or ion

reduction

the gain of electrons or a decrease in oxidation state by a molecule, atom, or ion

enzymes

- biological catalysts that work by lowering the activation energy for a reaction, thus dramatically increasing the rate of a reaction

- basis of metabolism

- reactions occur in the active site

- the folds are specific to certain enzymes: "lock and key model"

pancreatic acinar cell

- contains enzymes for digestion

- releases into the digestive tract

microvilli

- increases surface area for diffusion and minimizes increases in volume

- shares in the load of taking food in

levels of organizaion

- in the human body, chemical, cell, tissue, organ, organ system, organism

- everything has their own needs, and nutrients come from the blood

tissue

four general types:

- epithelial, connective, nervous, muscle

epithelial tissue

top layer of skin tissue

connective tissue

cartilage, bone tissue

nervous tissue

brain, nerve tissue

muscle tissue

heart, skeletal tissue

endocrine communication

- an example of distant communication

- hormones travel via bloodstream to tissues at large

paracrine communication

- an example of close communication

- communication that is cell to cell using chemical messengers

nutrient transport cells

- specialized cells work together to deliver and respond to nutrients

- in the small intestine, it's endocrine cell, capillary endothelium, nerve fiber, and epithelial cell

homeostasis

- regulation of internal constancy

- example: injecting insulin to regulate glucose levels

internal organs

brain, lungs, spleen, heart, larynx, kidneys, skeleton, etc.

scientific method

1) identify the problem

2) gather data

3) make a hypothesis

4) test the hypothesis (experiment)

5) make a model -> does the new data agree?

if no, then start at 3

if yes, then start at 4

falsifiability

- the capacity for some proposition, statement, theory or hypothesis to be proven wrong

- synonymous with testability

- "can something be tested"

correlation

- a statistical measure that indicates the extent to which two or more variables fluctuate together

- a positive correlation indicates the extent to which those variables increase or decrease in parallel

- DOES NOT IMPLY CAUSATION

association

unlike correlation, this does not give the extent of a relationship between two or more variables

how human studies differ from animal studies

1) cohort studies

2) prospective studies

3) retrospective studies

cohort studies

these studies involve following groups of people over time, with two primary purposes for these studies

prospective studies

the investigator defines the sample and measures the predictor variables before any outcomes have occurred

retrospective studies

- the investigator looks back on old data to find correlations

- the investigator defines the sample and measures the predictor variables after any outcomes have occurred

Dietary Reference Intakes (DRI's)

Amount of a nutrient needed to prevent deficiency disease in healthy people

Developed and published by the Institute of Medicine (IOM)

Represents the most current scientific knowledge on nutrient needs of healthy populations

calor

mass * velocity

kcal

1 = the increase of 1 kg of water 1 degree celsius

1000 calories

calorie

4.1858 joules

joule

1kg m^2s^-2

The Law of Constant Heat Sums

The total amount of heat consumed when a chemical system changes from an initial state to a final state is independent of the way in which change is brought about

Basal Metabolic Rate (BMR)

The rate at which the body uses energy while at rest to keep vital functions going

surface law

the metabolic rate (heat production per unit time) of an animal is proportional to their respective surface area

prediction of BMR

m = 0.75x^0.75

metabolic rate is proportional to weight to the 3^4 power

ways of measuring bmr

1) direct calorimetry

2) indirect calorimetry: the amount of oxygen consumed and carbon dioxide expelled

3) stable isotope methods

concentration gradients

particles called solutes move from an area of higher number of particles to an area of a lower number of particles, areas which are typically separated by a membrane

ATP

produced in the mitochondria

TCA Cycle

aka the Krebs Cycle

a series of enzyme-catalyzed reactions that form a key part of aerobic respiration in cells

methods for assessing body composition

bioelectric impedance analysis

skinfold thickness

underwater weighing

dilution method

radiologic methods

Factors Affecting BMR

age, growth, height, % lean tissue, fasting, starvation, malnutrition, fever, thyroxin, sleep

Positive Energy Balance

eating more energy than you use, gaining weigh

negative energy balance

eating less energy than you use, losing weight

Energy Out Processes

- basal metabolism

- thermic effect of food

- adaptive thermogenesis

- physical activity

Basal Metabolism

- energy to maintain life processes

- 70% of total energy body use depends on lean body mass

thermic effect of food

energy cost for digestion: 10% of kcal eaten

Fat: 0-5%

Carbs: 5-10%

Protein: 20-30%

Alcohol: 20%

glucose polymers

starch, glycogen, cellulose

all polysaccharides

adaptive thermogenesis

- heat production, shivering, excess heat from overeating, adaption to trauma, stress

- not usually included in energy calculations

Pair-Feeding

an experimental in which food intake or energy (calorie) intake are limited to be the same between animal groups and to exclude effects in animals by differences of food (energy) intake

pH

the level of acidity or alkalinity of a solution

intracellular fluid

- the fluid located inside the cell

- 2/3 of fluid is intracellular

extracellular fluid

- fluid outside the cell, such as interstitial fluid, blood plasma, lymph, spinal column

- 1/3 of fluid is extracellular

blood pressure

force exerted by blood on artery walls

dehydration

1-2% strong thirst

3-5% dry mouth, reduced urine output

6-8% muscle weakness, dizziness, exhaustion, increased body temperature

9-11% low blood volume and pressure, delirium

20% coma and death

*elderly and babies at risk

water needs

depends on age, body size, health status, etc.

Men: 3.7 L/day (3L from food and beverages)

Women: 2.7 L/day (2.2L food and beverages)

ways water can be lost

urinary losses

fecal losses

evaporative losses

sweat losses

osmosis

the movement of solvent (water) across the membrane from a region of relatively low concentration to a region of relatively high concentration (solute)

electrolytes

- function: regulate fluid balance, nerve and muscle response

- mineral salts separate solution into ions (carry electrical current)

- they move across membranes to maintain the appropriate electrolyte concentration and fluid via active transport (sodium potassium pump), active transport requires energy

functions of ions

1) control the osmosis of water between fluid compartments

2) maintaining acid-base balance required for normal cellular activities

3) production of action potentials

4) serving as cofactors needed for optimal activity of enzymes

acids

- chemical agents that release hydrogen ions when added to water

- can be classified as weak or strong depending on the amount of hydrogen ions that dissociate when placed in water