Unit 7 Flashcards
(120 cards)
1
Q
Why is food required for organisms to live?
A
- For growth - food provides substances needed for making new cells and tissues.
- As a source of energy - energy is required for the chemical reactions which keep organisms alive.
- For repair - food provides the substances needed to replace worn or damaged tissues.
2
Q
What is a balanced diet?
A
A diet which contains the appropriate amounts of various food substances needed in order to maintain a healthy standard of living.
3
Q
What sort of substances does a balanced diet contain?
A
Substances like:
- Carbohydrates
- Lipids
- Protein
- Vitamins
- Mineral salts
- Plant fibre
- Water
4
Q
What is energy used for in organisms?
A
- To keep internal body processes working (ex. Heart beating and breathing).
- To maintain a steady body temperature.
- To meet the energy requirements of any work and activities.
5
Q
How much energy is in 1gram of carbohydrates or protein?
A
About 16-17kJ
6
Q
How much energy is in about 1gram of fat?
A
About 37kJ
7
Q
How many kJ of energy does the average person need to obtain each day?
A
About 12000kJ
8
Q
What factors does the amount of energy required by a person vary?
A
- Occupation
- Level of activity
- Age
- Gender (females tend to require less energy as on average they have a smaller body mass than males).
9
Q
What is basal metabolism?
A
Where essential body functions such as: circulation, breathing, body temperature, brain function and other essential chemical processes are maintained during sleep.
10
Q
What are proteins used for in the body?
A
To build up the amino acids needed to build up body structures and proteins.
11
Q
What do vegans need to do?
A
They needed to make sure they eat variety of foods which contain the essential substances needed to maintain a healthy life.
12
Q
What are three factors which may alter a persons food requirements?
A
- Pregnancy
- Lactation
- Growing children
13
Q
What substances does a pregnant woman need to ensure they obtain in adequate quantities?
A
- Protein (for making the baby’s tissues).
- Calcium and vitamin D (required for bone development in the baby).
- Iron (required to make haemoglobin in the baby’s blood).
14
Q
What is lactation?
A
The production of breast milk.
15
Q
What substances does a lactating woman require?
A
Proteins, vitamins and calcium to produce milk of adequate quality and quantity.
16
Q
What is ingestion?
A
The taking in of substances such as food and drink into the body through the mouth.
17
Q
What is mechanical digestion?
A
The breakdown of food into smaller pieces without chemical change to the food molecules.
18
Q
What is chemical digestion?
A
The breakdown of large insoluble food molecules into small soluble molecules.
19
Q
What is absorption?
A
The movement of small food molecules and ions through the wall of the intestine into the blood.
20
Q
What is assimilation?
A
The movement of digested food molecules into the cells of the body where they are used, becoming part of the cells.
21
Q
What is egestion?
A
The passing out of food that has not been digested or absorbed, as faeces, through the anus.
22
Q
What is angina?
A
Chest pains due to a reduced blood supply to the heart.
23
Q
How does a heart attack occur?
A
When the diet contains too much fat, fatty substances can build up in the blood vessels and reduce the diameter of these blood vessels. Blot clots can then form leading to a heart attack.
24
Q
What is mastication?
A
The
25
What is kwashiorkor?
A type of protein-energy malnutrition that happens typically in a developing country where a mother has a baby, if they have a second baby soon after the first baby may be weaned on a diet with inadequate amounts of protein.
26
What are the symptoms of kwashiorkor?
1. Dry skin
2. Pot belly
3. Weakness
4. Irratibility
27
What is marasmus?
A form of malnutrition due to inadequate amounts of carbohydrates and protein.
28
What are the symptoms of marasmus?
1. Extremely thin and weak
2. Reduced fat and muscle tissue
3. Skin is thin and hangs in folds
29
How is marasmus different from kwashiorkor?
Kwashiorkor is where there is a lack of protein but enough energy, with marasmus there is a lack of both of these.
30
What foods is iron typically present in?
1. Red meat
2. Nuts
3. Shellfish
4. Dark green and leafy vegetables usually
31
What disease can a lack of iron cause?
A lack of iron in the diet can cause anaemia.
32
What is iron needed for?
Iron is needed to produce haemoglobin.
33
What is haemoglobin?
The protein in red blood cells responsible for transporting oxygen to respiring tissues.
34
What are the symptoms of anaemia?
1. Feeling weak
2. Tired
3. Irritable
35
What is significant about vitamin D compared to other vitamins?
It is the only vitamin that the body can manufacture (when the skin is exposed to sunlight).
36
What foods can provide vitamin D?
1. Oily fish
2. Butter
3. Milk
4. Egg yolk
37
What is vitamin D responsible for?
Vitamin D helps in the absorption of calcium and phosphorus through the gut wall.
38
What happens when a person has a lack of vitamin D?
Bone is made of a mineral called calcium phosphate. A lack of vitamin D therefore results in poor calcium and phosphate deposition in bones. This leads to softening of the bones.
39
What can a lack of vitamin D in children cause?
Rickets, the weight of the body can deform the bones in the legs.
40
What is a lack of vitamin D in adults cause?
Osteo-malacia, adults with osteo-malacia can be very susceptible to fracturing bones if they fall.
41
What is the alimentary canal?
A tube running through the body through which food passes through.
42
What is the inside of the alimentary canal lined with?
The epithelium which is formed by a layer of cells.
43
What does the epithelium produce?
Mucus
44
What is the purpose of mucus?
To lubricate the lining of the alimentary canal and protect it from wear and tear. It also can protect the lining of the canal from attack by digestive enzymes.
45
Where can digestive enzymes be produced?
1. In cells in the alimentary canal
| 2. In glands which are outside the alimentary canal
46
How do enzymes produced in glands enter the alimentary canal?
Through tubes called ducts.
47
What are examples of digestive glands?
1. Salivary glands
| 2. Pancreas
48
What is peristalsis?
Where areas of circular muscles contract one after another to create a wave of contraction which pushes food through alimentary canal.
49
What is diarrhoea?
Where
50
What is the function of the mouth?
To ingest food by breaking it down through MECHANICAL DIGESTION by teeth and the CHEMICAL DIGESTION of starch by amylase. A bolus is formed for swallowing.
51
What is the function of the salivary glands?
Saliva contains amylase for the CHEMICAL DIGESTION of starch. It also lubricates and makes small pieces of food stick together.
52
What is the function of the oesophagus?
Transfers food from the mouth to the stomach by peristalsis.
53
What is the function of the stomach?
Produces gastric juices for the CHEMICAL DIGESTION of protein, hydrochloric acid kills any bacteria. Peristalsis helps to churn food into a liquid.
54
What is the function of the duodenum?
The duodenum is the first part of the small intestine. It receives pancreatic juice for the CHEMICAL DIGESTION of proteins, fats and starch. It neutralises acid from the stomach. It receives bile to emulsify fats (this is a form of PHYSICAL DIGESTION).
55
What is the function of the ileum?
The ileum is the second part of the small intestine. Enzymes in the epithelial lining carry out CHEMICAL DIGESTION of maltose and peptides. It is very long and has villi to increase the surface area for the absorption of digested food molecules, this is ABSORPTION.
56
What is the function of the pancreas?
To secrete pancreatic juices into the duodenum through the pancreatic duct for the CHEMICAL DIGESTION of proteins, fats and starch.
57
What is the function of the liver?
Makes bile which contains salts to emulsify fats (PHYSICAL DIGESTION), there is the ASSIMILATION of digested food like glucose and there is the process of the deamination of excess amino acids.
58
What is the function of the gaul bladder?
Stores bile (made in the liver) and secretes it into the duodenum through the bile duct.
59
What is the function of the colon?
The colon which is the first part of the large intestine ABORBS water from undigested food and ABSORBS bile salts which pass back to the liver.
60
What is the function of the rectum?
The rectum is the second part of the large intestine and stores faeces.
61
What is the function of the anus?
To EGEST faeces.
62
How does cholera work?
If the cholera bacterium is ingested it multiplies in the small intestine and invades the epithelial cells. It then produces a toxin that causes the secretion of chloride ions into the small intestine, this causes osmotic movement of water into the gut. This results in diarrhoea which leads to dehydration and the loss of salts from the blood.
63
What is mastication?
The process of mechanical digestion in the mouth through using teeth.
64
What are the four types of teeth that humans have?
1. Incisors
2. Canines
3. Premolars
4. Molars
65
What do incisors do?
They cut pieces of food.
66
What do canines do?
They cut pieces of food.
67
What do premolars do?
Tear and grind food.
68
What do molars do?
Chew and grind food.
69
What is the crown of the tooth?
The part of a tooth visible above the gum line.
70
What is the gum?
The tissue that overlays the jaws.
71
What is the root of a tooth?
The part of a tooth embedded in the jaw bone.
72
What is the surface of the crown covered by?
A hard layer of enamel.
73
What is the cement in a tooth?
The layer on the outside of the root that enables the tooth to grip to its bony socket.
74
What is the dentine of a tooth?
The layer below the enamel, dentine is softer than enamel.
75
What is the pulp cavity in a tooth?
A cavity in the dentine which contains nerves and blood vessels. These enter the tooth through a small hole at the bottom of the root.
76
How does dental decay occur?
When bacteria on the surface of the tooth feed off the sugars deposited there. The bacteria respire these sugars which produces acid. These acids can dissolve the calcium salts in the tooth enamel leaving patches of enamel dissolved and exposing the dentine to the acids. This dentine will dissolve faster than the enamel as it is softer than the enamel.
77
What is the critical pH?
The pH below which the enamel is attacked.
78
How can tooth decay be prevented?
Avoiding eating sugar at frequent intervals and visiting the dentist around every six months.
79
What will happen if bacteria get into the pulp cavity of a tooth and cause a painful abscess at the root?
The tooth will normally have to be pulled out.
80
What contributes to the decay of teeth decay?
Refined sugar, that is, sucrose.
81
What food can be absorbed without digestion?
Glucose, for example in fruit juice.
82
What is the space inside the mouth called?
The buccal cavity.
83
What is another name for the throat?
The pharynx.
84
What prevents food passing down the windpipe?
The epiglottis (a flap of cartilage) guides the food into the oesophagus (gullet).
85
What is the pyloric sphincter?
A circular band of muscle at the lower end of the stomach which prevents food from passing through. When it opens food passes into the duodenum.
86
What happens in the stomach?
There is the peristaltic action of muscles in the stomach which churns and squeezes the food in the stomach while mixing it with gastric juices. This turns the mixture into a creamy liquid called chyme.
87
Why is food turned into chyme?
So that it can be digested faster as it has a greater surface area.
88
What produces gastric juice?
Glands in the lining of the stomach.
89
What enzyme is contained in gastric juice?
Protease.
90
What does protease do?
It helps to break down large protein molecules into small and soluble amino acids.
91
What two liquids are secreted into the small intestine?
Pancreatic juice and bile.
92
What enzyme does saliva contain?
Salivary amylase (sometimes called ptyalin), produced in the salivary glands.
93
What is the pancreas?
A digestive gland which produces food that acts on all classes of food.
94
What enzymes are in pancreatic juice?
1. Protease, breaks down proteins into amino acids.
2. Pancreatic amylase, converts starch to maltose.
3. Lipase, converts fats to fatty acids and glycerol.
95
What is bile?
A green, watery fluid made in the liver and stored in the gall bladder. It is delivered to the duodenum and it contains no enzymes.
96
What do bile salts do?
They emulsify fats, this means that the fats are broken up into small droplets with a large surface area so that they can be more efficiently digested by lipase.
97
What are two examples of proteases?
Pepsin and trypsin.
98
What does pepsin do?
Pepsin is a protease secreted into the stomach and operates in low pH conditions. It breaks down proteins into peptides.
99
What does trypsin do?
Trypsin is secreted into the duodenum and breaks proteins down into peptides.
100
What are peptides?
Soluble compounds that are made up shorter chains of amino acids than proteins.
101
What do crypts in villi do?
They produce new epithelial cells to replace those lost from the villi.
102
What do the epithelial cells of villi contain?
Enzymes in their cell membranes which complete the breakdown of sugars and peptides.
103
What does peptidase do?
It breaks down polypeptides and peptides into amino acids.
104
Where is starch digested?
In the mouth by salivary amylase and in the duodenum by pancreatic amylase.
105
What is amylase?
An enzyme which converts large and insoluble starch molecules into smaller and soluble maltose molecules, these are disaccharide sugars.
106
What is maltase?
An enzyme which breaks down maltose into glucose.
107
What is the importance of hydrochloric acid?
It denatures the enzymes in harmful organisms like bacteria and provides the optimum pH for the enzyme pepsin.
108
What enzymes can be found in the duodenum?
1. Proteases, like trypsin
2. Amylase
3. Lipase
109
What foods are are acted on in the duodenum?
1. Proteins and peptides
2. Starch
3. Fats
110
What enzymes are found in the ileum?
1. Maltase
| 2. Peptidease
111
What foods are acted on the in the ileum?
1. Maltose
| 2. Peptides
112
Where does nearly all of the absorption of digested food take place?
In the small intestine and mostly in the ileum rather thanthe duodenum.
113
Where does the absorption of water mostly take place?
Water is absorbed in the small intestine and colon, but most of the water is absorbed in the ileum.
114
Where do glucose and amino acids go when the are absorbed?
Once they are absorbed they enter the bloodstream.
115
Where do fatty acids and glycerol go once they are absorbed?
They pass into lacteals which are connected to the lymphatic system.
116
What materials pass into the large intestine?
Undigested and unabsorbed matter, cellulose and vegetable fibres, mucus and dead cells from the lining of the alimentary canal.
117
What does the colon absorb?
Fatty acids from plant fibre and bile salts which are returned to the liver.
118
What occurs in the small intestine?
The absorption of digested food.
119
What do villi and microvilli do?
They increase the surface area of the small intestine for the absorption of digested food molecules.
120
What is absorbed the the ileum?
Glucose, amino acids and fats.
