Define nutrient
a chemical that must be obtained by an organism from its environment in order to survive
Food for Growth and Maintenance
- carbohydrates
- proteins
- lipids
- water
- vitamins
- minerals
Broken down into simpler molecules that are used to build and repair bone, muscle, cells, and tissues.
Food for Energy
- all organisms need chemical energy
- humans obtain chemical energy carried in animal and plant-based foods
- cells in the body use chemical energy to fuel biological processes
Define metabolism
a set of chemical reactions that occur in living organisms that are necessary to maintain life
Define catabolism
the metabolic reactions that break down larger molecules into smaller subunits
Define anabolism
the metabolic reactions that use energy to produce larger molecules from smaller subunits
Metabolic rate
the rate at which the body converts stored energy into working energy
Factors that affect metabolic rate
- body size
- physical activity
- sex
- age
- hereditary factors
Measuring energy
1 calorie = 4180 J
Define macronutrients
a substance required in relatively large amounts by living organisms
- carbs, lipids, proteins, water
Define micronutrients
a chemical element or substance required in very small amounts by living organisms
- vitamins, minerals
Macronutrients: carbohydrates
- when we digest carbohydrates, they are broken down into simple sugar (monosaccharides)
- made up of C, H, O
- main energy source
- foods high in carbs are vegetables, fruits, potatoes, grains
3 types - Monosaccharides (ie. glucose)
- Disaccharides (ie. sucrose, table sugar)
- Polysaccharides (ie. cellulose, starch)
Macronutrients: protein
- when we digest proteins, they are broken down into amino acids
- made up of C, H, O, N
Functions - building blocks of cells
- involved in movement and biochemical reactions
- hormones
- enzymes
20 different types of amino acids - 12 non essential (can be made by the body)
- 8 essential (ie. through food)
Foods high in protein are meat, eggs, cheese, nuts
Macronutrients: lipids
- when we digest triglycerides (fats and oils), they are broken down into fatty
- made up of C, H, O
Functions - secondary source of energy after carbohydrates
- helps with absorption of vitamins
- insulation for the body
- some types of hormones
Saturated vs. Unsaturated fats
Saturated fats
- usually solid at room temp
- considered to be less healthy
- ie. butter
Unsaturated fats
- usually liquid at room temp
- considered to be more healthy
- ie. vegetable oil
Macronutrients: water
- the body is made up of 50-60% water
Functions - required to make cytoplasm of cell
- perform chemical reactions
- blood volume
- regulates blood temperature
- keeps skin moist
Replace water lost through: - urine
- sweat
- respiration
Micronutrients: vitamins
Fat-soluble (vitamins A, D, E, K)
- these vitamins can be stored in the body’s fatty tissues for future use
- not easy to eliminate excess from the body
Water soluble (vitamin B, C)
- cannot be stored in the body
- excess quantities can be excreted in urine
Most vitamins are from food, but vitamins A, D, and K, can be produced in our bodies
Vitamin A, D, K
Vitamin A
- the body can convert a chemical called beta-carotene into vitamin A
Vitamin D
- formed in the skin when skin is exposed to sunlight
- can produce enough vitamin D from 10-15 minutes of sunshine
Vitamin K
- is synthesized by a special bacteria found in the large intestine
Micronutrients: minerals
- minerals are naturally occurring elements that the body uses to carry out metabolic processes and to build or repair tissues
- An element required by the body in small amounts
- Ca, P, Na, Fe are prominent in our bodies (ie. Ca and P for bone formation, Fe for hemoglobin)
- F, Zn, Cu are present in our bodies in trace amounts
Specialized digestive systems: simple animals
gastrovascular cavity - a simple, sac-like digestive cavity that has only one opening where food goes in and wastes are expelled
- chemicals released into the cavity to break down food
- nutrients are absorbed by cells that line the cavity
- digestion continues in the cells
- nutrients diffuse from these cells to other cells of the body
ie. flatworms and jellyfish
Specialized digestive systems: complex animals
- Digestive tract with two openings, one for food and one for waste
- organized into specialized regions that enable the breakdown and absorption of food
Human Digestive System (4 main steps)
Gastrointestinal (GI) tract - the passageway or tube that extends from the mouth to the anus where the process of digestion takes place
1. Ingestion - the taking into the body of sources of nutrients, must be broken down in order for cells to use
2. Digestion - the breakdown of complex food molecules into smaller molecules
Chemical digestion - occurs in the mouth, stomach, and small intestine; chemicals mix with food to break them down into nutrients that could be absorbed
Physical digestion - occurs in the mouth and stomach; solid food is shredded, torn, ground, and mixed to break down food into smaller pieces, increasing the surface area for chemical digestion
3. Absorption - nutrients move from the intestine to the bloodstream
4. Egestion - removal of the waste food materials through the rectum and anus
Physical digestion in the mouth
- food is broken down into smaller pieces by the teeth
- type of teeth an animal has relates to its diet
1. Incisors - used for cutting
2. Canines - used for tearing
3. Premolars - used for grinding
4. Molars - used for crushing
Chemical digestion in the mouth
The presence of food in the mouth triggers the salivary glands to secrete saliva (made up of 90% water, electrolytes, enzymes, mucus)
- Enzymes (chemicals that increase the rate of reactions in living things, such as breaking down food)
ie. amylase is an enzyme that breaks down starch into disaccharides
