Unit 2 - Nutrition, Digestion, Excretion Flashcards Preview

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Flashcards in Unit 2 - Nutrition, Digestion, Excretion Deck (49)
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1

Carbohydrates - function

- important source of energy
- body prefers carbohydrates over all other available sources
- must be obtained from other organisms

2

Dehydration synthesis

glucose + glucose -> maltose + water

3

Hydrolysis

sucrose + water -> glucose + fructose

4

7 roles of proteins

1. Structural
2. Contractile
3. Storage
4. Defence
5. Transport
6. Signal
7. Enzymes

5

Enzymes - function

- act to catalyze activation energies of chemical reactions
- digestive enzymes are enzymes that break down food into usable material
- shape of enzyme must match substrate

6

Enzymatic reaction

1. Enzyme binds loosely to substrate at active site
2. Chemical change takes place at active site, resulting in two products
3. Products are released from active site

7

Lipids - function

- source of energy
- long term storage
- for making cell membranes and hormones, and for bringing in certain vitamins that are fat soluble

8

Fats and oils

- made from two different molecules, glycerol and fatty acids
- formula for fat formation is 1 glycerol, 3 fatty acids

9

Saturated fats

- carbon chains have single bonds; strong and hard to break down
- butter, lard, coconut oil

10

Monounsaturated fats

- one double bond between two carbons; less hydrogens present than in saturated fats
- olive oil, canola oil, peanut oil

11

Polyunsaturated fats

- more than one double bond between carbons; way less hydrogen
- fatty fish oil, avocado oil

12

Waxes

- long chained fatty acids combined with long chained alcohols
- creates insoluble molecules which act as waterproof coating for leaves, feathers, and fur

13

Steroids

- structurally different from other lipids
- consist of four linked rings of carbon atoms
- functions include chemical messengers (hormones), digestion (bile acids), and cell membrane structure (cholesterol)

14

Monosaccharides

- "one sugar"
- three types are glucose (aka blood sugar), fructose (aka fruit sugar), and galactose

15

Disaccharides

- "two sugars"
- formed chemically by the joining of two monosaccharides through dehydration synthesis
- sucrose (table sugar), lactose (milk sugar), and maltose (beer/bread making)

16

Polysaccharides

- few hundred to few thousand monosaccharides joined together by dehydration synthesis
- starch (plant storage), glycogen (animal storage), cellulose (plant fibre), chitin (protective exoskeletons of arthropods)
- can be split through hydrolysis

17

Mechanical digestion

Mouth: biting and chewing
Stomach: layers of muscle contract and churn

18

Chemical digestion

Mouth: saliva contains enzyme called amylase, digests starch molecules
Stomach: an enzyme called pepsin, and hydrochloric acid, digest large proteins into smaller proteins
Small intestine: pancreatic enzymes digest nutrients into simpler forms, bile assists in fat digestion (breaks down fat globules), protein digestion is accomplished by several enzymes

19

Where are carbs digested?

The mouth and small intestine

20

Where are proteins digested?

The stomach and small intestine

21

Where are lipids digested?

The small intestine

22

Examples of enzymes involved in digestion

Amylase digests starch
Pepsin digests proteins
Lipase digests lipids

23

Stages of digestion

1. Mouth
2. Esophagus
3. Stomach
4. Small intestine
5. Large intestine

24

Digestion in the mouth

- food changed mechanically by biting and chewing
- saliva binds food particles together into a soft mass called a bolus
- amylase digests stars molecules into smaller molecules (maltose)

25

Digestion in the esophagus

- esophagus is a thick walled muscular tube
- bolus moves through esophagus by peristalsis: rhythmic series of muscular contractions

26

Digestion in the stomach

- layers of muscle contract and churn food with gastric juices to form chyme
- enzyme called pepsin, and hydrochloric acid, digest large proteins into smaller proteins
- alcohol and sugar are absorbed by the stomach into the blood stream
- stomach stores food and prepares it for further digestion

27

Digestion in small intestine

- chyme enters through sphincter
- pancreatic enzymes digest nutrients into simpler forms
- bile enters from gall bladder to assist in fat digestion
- polypeptides are broken into amino acids
- most absorption occurs in the ilium
- products enter cells of villi, enter capillaries
- diffusion accounts for movement of most nutrients, but active transport is responsible for movement of glucose and amino acids
- absorption is completed in the jejunum

28

Digestion in large intestine

- substances not absorbed pass into large intestine
- main functions are to absorb water and to store, process, and eliminate residue following digestion and absorption
- intestinal matter (feces) remaining are stored in the rectum and passed out through the anus

29

Pancreas - function

secretes many digestive enzymes

30

Liver

- produces bile; mixture of salts, pigments, and cholesterol that breaks down globules of fat in the small intestine
- bile stored in gall bladder