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Digestive System Flashcards

1
Q

What is the importance of nutrients in digestion?

A

The digestive system** extracts nutrients** from food and absorbs them into the body for use by the cells.

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2
Q

What are the processes of the digestive system?

A
  • Ingestion of food and water
  • mechanical digestion of food
  • chemical digestion of food
  • movement of food along the alimentary canal
  • absorption of digested food and water
  • elimination of waste material that is not absorbed
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3
Q

What are nutrients?

A

Any substance that provides energy, is essential for growth, or assists in the functioning of the body.

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4
Q

What are the main types of nutrients?

A

Water, minerals, vitamins, carbohydrates, proteins, lipids.

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5
Q

What is the main energy source for the cell?

A

Carbohydrates

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6
Q

What are the types of carbohydrates?

A
  • Monosaccharides (e.g., glucose, fructose, galactose)
  • disaccharides (e.g., sucrose, maltose, lactose)
  • polysaccharides (e.g., glycogen, cellulose, starch)
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7
Q

What are lipids broken down into?

A

Fatty acids and glycerol for cellular respiration

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8
Q

What is the structure of lipid molecules?

A

Made of one glycerol molecule and 1-3 fatty acid molecules
- triglycerides = most common

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9
Q

What is the function of proteins?

A

Control cellular processes and build and repair cells

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10
Q

How many types of amino acids are there?

A

There are 20 different types of amino acids, of which 9 must be obtained from food.

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11
Q

What is a dipeptide?

A

Two amino acids bonded by a peptide bond.

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12
Q

What is a polypeptide?

A

More than 10 amino acids.

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13
Q

What is a protein?

A

100 or more amino acids.

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14
Q

What are organic compounds?

A

Compounds that contain a carbon chain, usually bonded to hydrogen
- carbohydrates
- proteins
- lipids
- RNA
- DNA
- vitamins

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15
Q

What are inorganic compounds?

A

Compounds that are not based on a carbon chain, usually do not contain carbon

  • water
  • minerals
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16
Q

What are the functions of nutrients?

A

carbs: provide energy for cells
proteins: build and repair cells
lipids: regulate body processes

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17
Q

What are carbohydrates made out of?

A
  • Hydrogen
  • carbon
  • oxygen
    twice as many hydrogen atoms as oxygen
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18
Q

What happens to excess protein in the body?

A

Converted to carbohydrates and used as an energy source.

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19
Q

What can hormones be made of?

A

can be proteins (e.g., insulin) or lipids (e.g., estrogen).

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20
Q

What is protein made up of?

A
  • carbon
  • hydrogen
  • oxygen
  • nitrogen
  • often sulfur and phosphorus
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21
Q

What are lipids made from?

A
  • carbon
  • hydrogen
  • oxygen
    less oxygen than carbohydrates
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22
Q

What is the role of nucleic acids?

A

Essential in forming DNA and RNA that stores genetic information.

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23
Q

What is the composition of nucleic acids?

A
  • carbon
  • hydrogen
  • oxygen
  • nitrogen
  • phosphorus
  • nucleotides:containing a nitrogen base, a sugar, and a phosphate
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24
Q

What are vitamins?

A

Small organic compounds that don’t provide energy but are essential for cells to gain energy from carbohydrates, lipids, and proteins.
act as **co-enzymes **for chemical reactions of metabolism

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25
Q

What are minerals?

A

May be part of enzymes, cofactors, or substances involved in metabolism, with 20 mineral elements essential for human body functioning.

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26
Q

What are the functions of water in the body?

A
  • Regulation of body temperature through perspiration, excretion of wastes
  • serving as a solvent for other substances.
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27
Q

How much water makes up the body?

A

Water makes up about 70% of the total weight of the body.

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28
Q

What needs to happen to nutrients for them to be absorbed?

A

Vitamins, minerals, and water must be small enough to pass through the semi-permeable cell membrane
carbohydrates, proteins, and lipids need to be broken down.

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29
Q

What is digestion?

A

The process of breaking down food particles small enough to be absorbed into the bloodstream.

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30
Q

What is mechanical digestion?

A

The physical breakdown of food to increase the surface area.

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31
Q

What is the aim of mechanical digestion?

A

To increase surface area for more successful chemical digestion.

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32
Q

What is chemical digestion?

A

The breakdown of complex molecules from food to smaller, simpler molecules by chemicals, referring only to enzyme action.

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33
Q

What makes up the alimentary canal?

A
  • mouth
  • oesophagus
  • stomach
  • small intestine
  • large intestine
  • rectum, and anus.
34
Q

What are the accessory organs of the digestive system?

A

Pancreas, liver, gallbladder.

35
Q

What is mastication?

A

The process of chewing food, done by teeth.

36
Q

What are the types of teeth?

A
  • Incisors -chisel-shaped, biting/cutting teeth (4)
  • Canines - sharp conical, tearing teeth (2)
  • Pre-molars - flat crowns, grinding teeth (4)
  • Molars - flat broad crowns crushing (or grinding) teeth (6)
37
Q

What happens after food is chewed in the mouth?

A

It is formed into a bolus by the tongue and pushed towards the pharynx for swallowing.

38
Q

What is the structure of the oesophagus?

A

A tube about 23-25cm long with a double layer of muscle.

39
Q

What happens to food in the oesophagus?

A

Food moves through the pharynx to the stomach, lubricated by mucus and moved by peristalsis.

40
Q

What is the function of the epiglottis?

A

Closes off the trachea, preventing food from entering the lungs.

41
Q

What is peristalsis?

A

The wave-like muscle contractions that move food through a tube such as the oesophagus.

42
Q

What happens in the stomach during mechanical digestion?

A

Waves of muscular contraction churn food to produce chyme.

43
Q

What are the layers of muscle in the stomach?

A

Circular layer, longitudinal layer, and additional oblique layer.

44
Q

What is the chemical digestion in the stomach?

A

Enzymes in gastric juice secreted by gastric glands.

45
Q

What are the contents of gastric juice?

A
  • HCl (destroys bacteria)
  • mucus (protects stomach tissue)
  • pepsinogen (activated to pepsin)
46
Q

What is the function of gastric glands?

A

Located in gastric pits, they secrete gastric juice.

47
Q

What is the pyloric sphincter?

A

A thickening of circular muscle at the bottom of the stomach that controls the flow of material into the duodenum.

48
Q

How long does food usually stay in the stomach?

A

Pushed through after 2-8 hours.

49
Q

What can be absorbed in the stomach?

A

Alcohol, glucose, and drugs (e.g., aspirin).

50
Q

What is the structure of the small intestine?

A

6m long and consists of

three sections: Duodenum, Jejunum, Ileum.

51
Q

What is segmentation in the small intestine?

A

Circular muscle contraction that breaks up the bolus further and brings it into contact with the lining for absorption.

52
Q

What is bile?

A

Produced in the liver
stored in the gallbladder
enters the intestine through the common bile duct

  • doesn’t contain enzymes so is a mechanical digestion*
53
Q

What is the role of bile?

A
  • maintains intestinal pH by neutralizing stomach acids
  • physically breaks down large fat droplets
54
Q

What are the pancreatic enzymes?

A
  • Amylase: starch -> maltose
  • Trypsin: proteins -> polypeptides
  • Lipase: lipids -> fatty acids and glycerol
  • Ribonuclease and Deoxyribonuclease: digests RNA and DNA
55
Q

What are intestinal enzymes?

A

Maltase: maltose -> glucose
Sucrase: sucrose -> glucose
Lactase: lactose -> fructose
Peptidase: dipeptides -> amino acids
Lipase: : lipids -> fatty acids and glycerol

56
Q

What makes absorption more efficient in the small intestine?

A

Surface area:
- long length (6m)
- highly folded inner lining walls (mucosa)
- villi
- microvilli
- extensive capillary network

57
Q

What is a villus?

A

1mm long and covered by a single layer of cells with a single lymph capillary (lacteal) surrounded by blood capillaries

muscular contractions in the small intestine that keep the contents moving along to maintain the concentration gradient

58
Q

How are nutrients transported in the small intestine?

A

Monosaccharides and amino acids via active transport, water and minerals via osmosis, fatty acids and glycerol via simple diffusion.

59
Q

What is the pathway of nutrient transport in the small intestine?

A

Monosaccharides
Active transport into the blood capillaries

Amino acids
Active transport into the blood capillaries

Water, minerals and water-soluble vitamins
Osmosis into blood capillaries

Fatty acids and glycerol, and lipid-soluble vitamins
Simple diffusion into the villi where they recombine and then enter the lacteal

60
Q

What is the structure of the large intestine?

A
  • 1.5m long
  • made up of caecum, appendix, colon, rectum, and anus (external opening with anal sphincter)
61
Q

What happens in the large intestine?

A

Contents are pushed into the rectum by peristalsis
absorbs remaining water (making contents solid), minerals and vitamins (that are produced from bacteria)

62
Q

What is defaecation?

A

Triggered as the walls stretch, resulting in the passing out of faeces

referred to as elimination (NOT EXCRETION)
excretion = removal of metabolic waste (waste produced from chemical reactions)
elimination = removal of indigestible material, bacteria and bile pigments from the body

63
Q

What are the contents of faeces?

A
  • water
  • undigested food (mainly cellulose)
  • bacteria
  • bile pigments
  • remains of cells from the canal lining.
64
Q

What is ingestion?

A

The intake of food, liquids, or drugs into the mouth.

65
Q

What is the function of the oral cavity/mouth?

A

Ingestion of food.

66
Q

What is the function of the oesophagus?

A

Connects pharynx to the stomach.

67
Q

What is the function of the duodenum?

A

Continues chemical digestion (of proteins) in the small intestine.

68
Q

What is the function of the jejunum?

A

Absorption of carbohydrates and proteins in the small intestine.

69
Q

What is the function of the ileum?

A

Remaining products of digestion are absorbed.

70
Q

What is the role of segmentation?

A

Breaks up the bolus further and mixes contents with juices and bile.

71
Q

How long does food stay in the large intestine?

A

18-24 hours to pass through.

72
Q

What are the functions of the stomach?

A
  • Mechanical digestion through churning to create chyme
  • chemical digestion of pepsin to digest proteins
  • creating an acidic environment through HCl
73
Q

What is the function of the large intestine?

A
  • Absorbs water and vitamins
  • stores faeces
  • facilitates defaecation
74
Q

What is the pathway of bile?

A

Liver -> gallbladder -> common bile duct -> small intestine.

75
Q

What are other carbohydrate enzymes?

A

sucrase breaks down sucrose into glucose
lactase breaks down lactose into fructose
maltase breaks down maltose into glucose

76
Q

What are the features of villi (MR SLIM)?

A
  • Microvilli increase surface area
  • Rich blood supply rapidly
    -** T**ransports absorbed products
  • Single layer epithelium minimizes diffusion distance
  • Lacteals absorb lipids
  • Intestinal glands release digestive juices.
  • Membrane proteins – Facilitates transport of digested materials into epithelial cells
77
Q

What are the type of cells on the lining of the villus?

A

epithelial - absorptive cell
goblet - secretory cell

78
Q

Rectum

A

facilitates defaecation through peristalsis

79
Q

Colon

A

longest part of the small intestine
sections
-ascending
- transverse
- descending

80
Q

Caecum

A

pouch about 6cm long that joins small intestine to large intestine

81
Q

Appendix

A

small tube attached to caecum

Human Bio (7 decks)

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