Y2 Science > Human Digestive System > Flashcards

Human Digestive System Flashcards

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1
Q

What are biological molecules

A

Critically important molecules needed for organisms to survive.

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2
Q

What is the importance of biological molecules

A

Fuel for vital activities to keep body alive
Cell growth, repair of worn-out parts of the body
Cell division
Maintenance of good health

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3
Q

What are nutrients

A

Chemical substances in food that provide energy and materials needed by the body

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4
Q

Types of biological molecules

A

Carbohydrates
Proteins
Lipids

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5
Q

Molecule size of carbohydrates

A

Can be either big or small

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6
Q

Function of carbohydrates

A

An immediate source of energy
Some carbohydrates make up fibre that body can’t digest. Fibre passes out undigested and forms bulk of faeces. For plants, cellulose form supporting structures such as cell wall in plants

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7
Q

Examples of carbohydrates

A

Starch
Sugar
Cellulose

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8
Q

Molecule size of protein

A

Very large

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9
Q

Function of proteins

A

To make new cells for body growth and repair worn out tissues

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10
Q

Examples of protein

A

Milk
Fish
Dairy products
Egg whites

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11
Q

Molecule size of lipids

A

Very small

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12
Q

Function of lipids

A

Energy reserve and acts as insulation against heat loss from body

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13
Q

Examples of lipids

A

Butter
Oil
Cheese

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14
Q

What are enzymes

A

Biological catalysts that are made up of protein most of the time

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15
Q

What are catalysts

A

Chemical substances that help to speed up chemical reactions without themselves being chemically changed at the end of reactions

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16
Q

Define enzymes

A

Enzymes are biological catalysts. They speed up rate of chemical reactions without themselves being chemically changed at the end of reactions

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17
Q

Classification of enzyme-catalysed reactions

A

Build up complex substances (photosynthesis, protein synthesis)
Break down complex substances (respiration, digestion)

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18
Q

Characteristics of enzymes

A

Enzymes speed up chemical digestion
Enzymes remain chemically unchanged after the reaction
Enzymes are specific in action
Enzymes are affected by extreme pH and temperature

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19
Q

How does enzymes speed up chemical reactions

A

Lowering energy needed for a reaction to take place
In terms of digestion, this helps in breaking down food into simpler substances

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20
Q

Why are enzymes required in small concentrations

A

Enzymes remain chemically unchanged so they can be used over and over again

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21
Q

Benefit of enzymes being chemically unchanged

A

Can be used over and over again so they are required in small concentrations

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22
Q

Why is an enzyme specific in action

A

It has a 3D shape

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23
Q

What is the alimentary canal

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A

A tube that extends from the mouth to the anus, with most of its length coiled in the abdomen or abdominal cavity

24
Q

What does the alimentary canal consist of

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A

Mouth
(O)esophagus
Stomach
Small intestine
Large intestine
Rectum
Anus

25
Processes that happen in the alimentary canal
Ingestion (mouth) digestion (mouth to small intestine) absorption (small intestine) egestion (anus)
26
Associated organs and glands with the alimentary canal
liver pancreas gall bladder
27
Define digestion
Digestion is the process that breaks down large, insoluble, complex food substances into small, soluble, simple molecules
28
Why is digestion necessary
Small, soluble molecules are small enough to be easily absorbed into the cells of the small intestine and the rest of the body.
29
Types of digestion taking place in the alimentary canal
Physical digestion Chemical digestion
30
Why is physical digestion
Breaking UP of food into smaller pieces
31
Examples of physical digestion
Chewing (teeth) churning (stomach) bile emulsification
32
Why is physical digestion needed
Increase surface area to volume ratio of ingested food so that enzymes can digest it more efficiently
33
What is chemical digestion
Breaking down large molecules into soluble molecules by digestive enzymes
34
Why is chemical digestion needed
Small soluble molecules can be easily absorbed by cells in the small intestine
35
Processes of digestion in the mouth
Chewing or mastication, breaks up solid food into smaller pieces Salivary glands produce saliva which helps to moisten and soften food Saliva also contains a digestive enzyme called salivary amylase Tongue rolls up chewed food into a small ball (bolus) which is swallowed
36
How does chewing help in digestion
Increase surface area to volume ratio to increase rate of starch digestion by salivary amylase
37
How does saliva help in digestion
Makes food easier to swallow
38
How does salivary amylase help in digestion
Digests starch into maltose
39
What is the oesophagus
Narrow, muscular tube connecting mouth to stomach
40
What happens in the oesophagus
The bolus is moved along the oesophagus by peristalsis to mix and propel the contents in the alimentary canal Pushes bolus to stomach No digestive enzymes are released in the oesophagus but starch digestion by salivary amylase may continue
41
What is peristalsis
Rhythmic, wave-like contractions of the muscles of the muscles along the digestive tract
42
What happens during digestion in stomach
Stomach is large, elastic bag Walls of the stomach are lined with gastric glands that secrete gastric juices Gastric juices contains hydrochloric acid and pepsin Pepsin digests proteins into polypeptides Churning occurs
43
How does churning in the stomach help in digestion
Mixes food with gastric juice into a liquid called chyme. This increases surface area to volume ratio to increase rate of protein digestion by pepsin
44
What happens during digestion in the small intestine
6m long Chyme from the stomach enters the first part of small intestine Digestion is small intestine is aided by secretions from other associated organs: the liver, gall bladder and pancreas Walls of small intestine contain glands which secrete digestive enzymes Digestion is complete here Carbohydrates are digested into glucose Proteins are digested into amino acids Lipids are digested into fatty acids and glycerol Most water and mineral salts are absorbed into the bloodstream in the small intestine
45
How does gall bladder and liver help in digestion
Liver is largest gland in the body. Produces bile. Bile is stored in the gall bladder and is released by the small intestine via the bile duct
46
What is bile
Alkaline, greenish-yellow liquid
47
How does bile help with digestion
Bile emulsifies lipids by breaking up large fat droplets into tiny fat droplets This increases the surface area to volume ratio to increase rate of lipid digestion by lipases Lipid emulsification by bile is a form of physical digestion Bile helps to neutralise the acidic chyme from the stomach
48
How does pancreas help in digestion
Gland that produces pancreatic juice Pancreatic juice is alkaline, which neutralise acidic chyme from stomach Pancreatic juices contains various digestive enzymes
49
Digestive enzymes in pancreas
Pancreatic amylase Trypsin Pancreatic lipase
50
Digestion of pancreatic amylase
From starch to maltose molucules
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Digestion of Trypsin
Digest proteins to polypeptides
52
Digestion of pancreatic lipase
Digest lipids to fatty acids and glycerol
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Digestive enzymes released by small intestine
carbohydrases digests disaccharides into monosaccharides Peptidase digests polypeptides to individual units of amino acids Intestinal lipase digests lipids to fatty acids and glycerol
54
What happens in the large intestine
1.5m in length Absorbs remaining water and mineral salts from undigested matter. Results in formation of faeces Faeces is temporarily stored in the rectum
55
What is egestion
When the rectum is full, the muscles contract and expel faeces via the anus
56
How are products absorbed in the small intestine
Products of digestion like sugars, amino acids, fatty acids and glycerol are absorbed throughout the small intestine into the circulatory system These products are the carried by the circulatory system to tissues around the body In the tissues, the products of digestion diffuse out of the blood capillaries into cells to be utilised
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