Pack 4 – Digestive System, Carbohydrates and Lipids Flashcards
(178 cards)
1
Q
Polymers
A
Large molecules
2
Q
Monomers
A
When polymers are broken down into chunks
3
Q
Structural features of the pancreas:
A
An elongated, tapered organ which is a gland
4
Q
Function of the pancreas:
A
Makes enzymes (lipase, amylase, protease)
5
Q
Structural features of the large intestine:
A
Made up of the colon and the rectum
6
Q
Function of the large inestine:
A
Absorbs water from waste food.
Stores waste until it leaves the body as faeces through the anus
7
Q
Structural features of the stomach:
A
- Hollow organ with muscular walls which produce gastric juice
- Contains hydrochloric acid (to create a low
pH for enzymes to work)
8
Q
Function of the stomach:
A
Protein digestion using enzymes like pepsin
9
Q
Structural features of the gall bladder:
A
Pear shaped hollow structure found under the liver
10
Q
Function of the gall bladder:
A
Stores bile (which is made by the liver).
Bile breaks down lipids into droplets in the small intestine
11
Q
Structural features of the duodenum:
A
- First section of the small intestine
- C shaped and around 23-28 cm long
12
Q
Function of the duodenum:
A
Digestion of larger carbohydrates, fats and proteins found in chyme (from stomach)
13
Q
Structural features of the ileum:
A
Final section of the small intestine.
Long (3m) tube
14
Q
Function of the ileum:
A
Absorption of nutrients from digested food into the blood. Villi increase the surface area for absorption
15
Q
What are the 2 main forms of digestion:
A
Mechanical and chemical digestion
16
Q
Mechanical digestion:
A
- Involves the action of teeth and muscle contractions
- It helps mix food and increase its surface area for enzyme action
17
Q
Chemical digestion
A
When enzymes, which are secreted by the digestive system, break food down by hydrolysis
18
Q
Function of digestive enzymes:
A
- Designed to break down polymer chains into their constituent monomers
- Different digestive enzymes break down different types of food
- Enzymes work through a process called hydrolysis
19
Q
Hydrolosis:
A
Breaking down a large molecule into a smaller one, using water
20
Q
Carbohydrates enzyme:
A
Amylase
21
Q
Where is amylase produced?
A
Salivary glands and pancreas
22
Q
Amylase location of action:
A
Mouth and small intestine
23
Q
Amylase polymer broken down:
A
Starch
24
Q
Amylase product:
A
Maltose
25
Amylase optimum conditions:
Slightly acidic to neutral pH (pH 6.8)
26
Amylase digestion equation:
Starch + water -> maltose
27
Lipids enzyme:
Lipase
28
Where is lipase produced?
Pancreas
29
Lipase location of action:
Small intestine
30
Lipase polymer broken down:
Fats
31
Lipase product:
Monoglycerides and fatty acids
32
Lipase optimum conditions:
Slightly alkaline pH
(pH 8)
33
Lipase digestion equation:
Fat droplet + water
-> monoglycerides and fatty acids
34
Proteins enzyme:
Pepsin and trypsin
35
Where is pepsin produced?
Gastric glands
36
Pepsin location of action:
Stomach
37
38
Pepsin polymer broken down:
Protein
39
40
Pepsin product:
Peptides
41
42
Pepsin optimum conditions:
Acidic/low pH
(pH 1-2)
43
44
Pepsin digestion equations:
Protein + water -> peptides
45
46
Where is trypsin produced?
Pancreas
47
48
Trypsin location of action
Small intestine
49
50
Trypsin polymer broken down:
Protein
51
52
Trypsin product:
Peptides
53
54
Trypsin optimum conditions:
Slightly alkaline pH
(pH 8)
55
56
Trypsin digestion equation:
Protein + water -> peptides
57
58
How is food absorbed in the small intestine?
Through the walls, into the blood (capillaries) or lymph (lacteals)
59
60
3 features of the small intestine:
1. Many villi (and microvilli) - create a large surface area
2. Thin wall (one-cell-thick) - reduces diffusion distance
3. Good blood supply/many capillaries present - reduces diffusion distance
61
62
Carbohydrate digestion:
- Polysaccharides are digested by amylases located in saliva and pancreatic juice, so digestion begins in the mouth
- Pancreatic amylase continues the digestion of polysaccharides in the small intestine
63
64
Carbohydrates absorption:
- Glucose enters the epithelial cells lining intestinal villi via cotransport with sodium - It then moves by facilitated diffusion into the capillaries
65
66
Proteins digestion:
- Pepsin becomes inactive in the alkaline lumen of the small intestine
- Trypsin carries out further digestion in the small intestine
67
68
69
Proteins absorption:
- Amino acids are actively transported into intestinal epithelial cells by cotransport with sodium
- Amino acids are then transported by facilitated diffusion into the blood
70
71
Lipids digestion:
- Digestion of lipids begins in the mouth and continues in the stomach by the action of lipases
- Most digestion of lipids does not take place until the lipids reach the small intestine
- In the small intestine, bile breaks down these fat globules into smaller droplets (emulsification)
- Triglycerides are broken down into fatty acids and glycerol
72
73
Lipids absorption:
- The fatty acids and glycerol move by simple diffusion into intestinal epithelial cells
- There, they are reassembled into triglycerides
- They then enter the lymphatic system via the lacteals
- The flow of lymphatic fluid eventually carries them to the bloodstream.
74
75
Vitamin B role in the body:
coenzymes and aid processes such as respiration
76
77
Source of vitamin B:
Cereals, wholemeal bread, green leafy vegetables
78
79
Vitamin A role in the body:
Dim-light vision, for healthy epithelial tissue and for the immune system
80
81
Source of vitamin A:
Liver, green vegetables, orange vegetables and fruits
82
83
Vitamin C role in the body:
Helps make connective tissue and helps us absorb iron from food
84
85
Source of vitamin C:
Citrus fruits, blackcurrants, kiwi fruits, potatoes, peppers
86
87
Vitamin D role in the body:
Helps us absorb calcium from food and deposit it in bones; it also protects us from cancer and heart disease
88
89
Source of vitamin D:
Oily fish, egg yolk, liver; made in skin when exposed to sunlight
90
Role of iron in the body:
Needed for making haemoglobin that carries oxygen in erythrocytes
91
Source of iron:
Red meat, spinach, dried apricots
92
Role of calcium in the body:
Hardens bones and teeth, helps blood clot, helps nerve conduction, helps muscles contract
93
Source of calcium:
Milk, yoghurt, cheese, broccoli
94
Role of sodium and potassium in the body:
Nerve conductions and heart function
95
Source of sodium:
Table salt
96
Source of potassium:
Bananas
97
Role of magnesium in the body:
For bones
98
Source of magnesium:
Green vegetables
99
Role of iodine in the body:
For thyroxine
100
Source of iodine:
Table salt, sea food
101
Role of zinc in the body:
For insulin
102
Source of zinc:
Meat, cereals, nuts, milk
103
Role of carbohydrates in the body:
The main source of energy
104
Source of carbohydrates:
Potatoes, rice, cassava, millet, bread
105
Role of lipids in the body:
- Protect organs from knocks
- Can be used as a source of energy
- Long-chain omega 3 fatty acids in fish oils protect us from heart disease
106
Role of proteins in the body:
Used to make enzymes, hormones, antibodies, haemoglobin, muscles, cell membranes, collagen and elastin in connective tissue, bone, and for growth and repair of tissues
107
Source of protein:
Soya, milk, meat, eggs, fish, nuts, cheese
108
Role of fibre in the body:
- Takes up water when in the gut
- It helps us pass faeces easily
- Soluble fibre helps to lower blood cholesterol levels`
109
Source of fibre:
Corn, potatoes with skin, soluble fibre in oatmeal, baked beans
110
Role of water in the body:
- Makes up 70% of us – blood plasma is 90% water, so water is needed for transport in the body
- Needed for sweat, tears and urine
111
Source of water:
Milk, drinks such as tea and coffee, juice, fruit and vegetables
112
1 calorie
The quantity of heat energy required to raise the temperature of 1cm3 of water by 1 degree
113
How many calories do men require per day?
2500kcal
114
How many calories do women require per day?
2000kcal
115
How do we measure calories in food?
Bomb calorimeter
116
How does a bomb caloriemeter work?
- It combusts a known mass of the food to increase the temperature of a known volume of water
- These values are then used to work out the amount of energy released by the food
- This can then be converted into calories
117
BMI equation:
BMI = weight (KG)
-----------------
Height^2 (m^2)
118
Normal range of glucose in the blood:
70 mg/dl - 110 mg/dl
119
Hypoglycaemia glucose in the blood:
: below 70 mg/dl
120
Hyperglycaemia glucose in the blood:
180 mg/dl
121
Diabetes glucose in the blood:
Above 200 mg/dl after a glucose tolerance test
122
What happens in the event of high blood glucose levels:
- Beta cells release the hormone insulin
- Insulin stimulates muscle, red blood cells, and fat cells to absorb glucose out of the blood
- The liver converts excess glucose into glycogen for storage
123
What happens in the event of low blood glucose levels:
- Alpha cells release the hormone glucagon
- The body cells do not absorb as much glucose from the blood
- Glucagon stimulates the liver to convert glycogen into glucose and release it into the bloodstream
124
Diabetes mellitus
A condition where someone’s blood sugar levels are too high
125
What are the 2 types of diabetes
Type 1 and type 2 diabetes
126
Type 1 diabetes:
Where the body's immune system attacks and destroys the cells that produce insulin
127
Type 2 diabetes:
Where the body doesn't produce enough insulin, or the body's cells don't react to insulin
128
Type 1 diabetes process:
The immune system destroys the beta cells in the pancreas that make insulin
- This leaves the body without enough insulin to control blood sugar levels
129
Type 2 diabetes process:
The insulin receptors on body cells lose their sensitivity, leading to a lack of uptake of glucose by cells, so it remains in the blood
130
Type 1 diabetes causes:
- Viral or bacterial infection
- Chemical toxins within food
- Unidentified component causing autoimmune reaction
131
Type 2 diabetes causes:
- Obesity
- High blood pressure
- Increasing age
132
What are biological molecules made up of?
Single units called monomers
133
2 monomers joined together:
Dimer
134
3 or more monomers joined together:
Polymer
135
Carbohydrates formula:
Cx(H2O)n
136
Monosaccharides general formula:
(CH2O)n
137
What does n = in (CH2O)n
The number of carbon atoms in a molecule
138
How many carbon atoms do most monosaccharides have?
6
139
Hexose sugars
The 6 carbon atoms within a monosaccharide
140
What do monosaccharides provide?
- A rapid source of energy
- They are readily absorbed and require little or, in the case of glucose, no change before being using in cellular respiration
141
What are the 2 glucose isomers?
α glucose and ß glucose
142
α glucose
Alpha glucose is the monomer of the polysaccharides starch and glycogen
143
ß glucose
The monomer of the polysaccharide cellulose
144
Making disaccharides:
- Two monosaccharides join by a condensation reaction to form a disaccharide
- The units are joined by a glycosidic bond
- A water molecule is released as the two sugar molecules combine in the reaction
145
Maltose monosaccharide constituents:
Glucose + glucose
146
Maltose role in nature:
Produced when amylase breaks down starch
147
Sucrose monosaccharide constituents:
Glucose + fructose
148
Sucrose role in nature:
Transport sugar in plants
149
Lactose monosaccharide constituents:
Glucose + galactose
150
Lactose role in nature:
Sugar in milk
151
How is a disaccharide broken down?
Hydrolysis
152
Polysaccharides
- Polymers made from three or more monosaccharides, joined by glyosidic bonds into long straight or branched chains
- Each sugar monomer is joined to the chain in a condensation reaction with a water molecule released during the reaction
153
2 main types of polysaccharide found in food:
1. Starch and cellulose in plants
2. Glycogen in animals
154
Amylose structure:
Straight chain of between 200 and 5000 glucose molecules with 1,4 glyosidic bonds between adjacent glucose molecules
155
Starch structure:
Amylose and amylopectin
- Insoluble and compact, ideal for storing the energy provided by the glucose molecules
156
Amylopectin structure:
1,4 glyosidic bonds between adjacent glucose molecules, but it has side branches
157
Animals energy store:
Glycogen
158
Glycogen polymer:
Glucose
159
Where is glucose stored in humans?
Liver and muscles
160
Glucose structure:
- Insoluble in water and is more compact than starch
- It can be rapidly hydrolysed due to numerous side branches giving easy access to stored energy (glucose)
161
Cellulose
Dietary fibre
162
Cellulose function:
Movement of material through the digestive tract
163
What diseases does dietary fibre prevent?
CHD, diabetes and bowel cancer
164
What are most of the lipids we eat?
Triglycerides
165
Triglycerides structure:
Made up of three fatty acids and one glycerol molecule linked by condensation reactions
166
Ester bond
The bond that forms between each fatty acid and the glycerol
167
How many ester bonds are formed in a triglyceride?
3
168
Saturated fatty acid
The hydrocarbon chain is long and straight
169
Saturated fatty acids structure:
There are no carbon to carbon double bonds in the saturated fatty acid chain and no more hydrogens can be added to it
170
Major sources of saturated fats:
Meat and dairy products
171
How are fatty acids solid at room temperature?
Due to the strong intermolecular bonds between triglycerides made up of saturated fatty acids
172
Monounsaturated fats structure:
One double bond between two of the carbon atoms in each fatty acid chain
173
Polyunsaturated fats structure:
- A larger number of double bonds
- A double bond causes a kink in the hydrocarbon chain
174
How are unsaturated triglycerides liquid at room temperature
- Kinks prevent the unsaturated hydrocarbon chain packing closely together
- Increasing the distance between the molecules weakens the intermolecular forces
175
Sources of polyunsaturated fats:
Vegetable oils, nuts and fish
176
Cholesterol function:
Regulating the fluidity of cell membranes and making steroid
177
How is high levels of blood cholesterol caused?
A diet high in saturated fat
178
High blood cholesterol leads to:
Risk of developing conditions such as coronary heart disease and strokes
