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5th Year Biology > Chapter 33 - The Human Digestive System > Flashcards

Chapter 33 - The Human Digestive System Flashcards

1
Q

Define Digestion.

A

Breaking down of food into its constituent molecules so they can be absorbed into the bloodstream.

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2
Q

Define Egestion.

A

Removal of undigested food.

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3
Q

Define Excretion.

A

Removal of waste products of digested food.

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4
Q

What are the two types of digestion?

A
  1. Physical (Mechanical)

2. Chemical

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5
Q
  1. Physical Digestion
A

Mechanical breakdown of food using teeth and muscle.
Food parts go from large to small.
Through processes such as peristalsis (oesophagus)

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5
Q
  1. Physical Digestion
A

Mechanical breakdown of food using teeth and muscle.
Food parts go from large to small.
Through processes such as peristalsis (oesophagus)

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6
Q
  1. Chemical Digestion.
A

Involves the chemical breakdown of food using enzymes.
Food is broken down into its simplest unit.
E.g Starch to Glucose.

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7
Q

What are the 5 stages of digestion?

A
  1. Ingestion
  2. Digestion
  3. Absorption
  4. Assimilation
  5. Elimination
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8
Q

Ingestion

A
  • Taking in Food (consumption)

- Occurs in the mouth

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8
Q

Ingestion

A
  • Taking in Food (consumption)

- Occurs in the mouth

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9
Q

Absorption

A

Simplest substance being taken into the bloodstream through the lining of the alimentary canal.

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10
Q

Absorption

A

Simplest substance being taken into the bloodstream through the lining of the alimentary canal.

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10
Q

Absorption

A

Simplest substance being taken into the bloodstream through the lining of the alimentary canal.

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11
Q

Assimilation

A

Putting food to use in the body.

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12
Q

Elimination

A

Egestion- Removal of undigested waste

Excretion - Removal of waste after digestion.

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13
Q

Polymer and Monomer

A
  1. Starch ——- Glucose
  2. Fat ——– Triglyceride
  3. Protein ——- Amino Acids
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14
Q

Alimentary Canal

A

This is a long muscular tube that runs through the body from the mouth to the anus.

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14
Q

Mouth

A
  • Release saliva.
  • Saliva is made of a combination of water, mucus and amylase.
  • Water and mucus moisten and lubricates the food making it easier to swallow.
    amylase
    -Starch —————– Maltose
    -Works best in a slightly alkaline environment (pH 7.5)
    -Food is chewed and lubricated until a bolus is formed (Ball of food). This bolus moves back the throat into and down the oesophagus.
15
Q

Teeth

A
  • There are four types of teeth.
  • Incisors, Canines, Pre-molars and Molars.
  • Breakdown of food into smaller pieces so it is easier to move down the oesophagus/ swallow. And is also a greater surface area for enzymes to work on.
  • Total No. of teeth in adults is 32
  • Total No. of teeth in children is 20.
16
Q

Incisors

A

Function - Cut and bite
No. in adults - 8
No. in children - 8

17
Q

Canines

A

Function - Cut and tear
No. in adults - 4
No. in children - 4

18
Q

Pre-Molars

A

Function - Crush and grind
No. in adults - 8
No. in children - 8

19
Q

Molars

A

Function- Crush and grind
No. in adults - 12
No. in children - 0

20
Q

Dental Formula

A

Tells us the number of each tooth on the upper and lower jaw of one side of the mouth.

  • I = 2/2
  • C = 1/1
  • Pm = 2/2
  • M= 3/3
21
Q

Oesophagus

A
  • Long muscular tube beginning at the throat and ending at the stomach.
  • Moves food from the mouth to the stomach by peristalsis.
  • Peristalsis - The contracting and relaxing of the muscles in the oesophagus.
22
Q

What is the Cardiac Sphincter Muscle?

A

Relaxes to allow food from the oesophagus into the stomach. The muscle also contracts to prevent any food or gastric juices from re-entering the oesophagus.

23
Q

How is food digested in the Stomach?

A

Food remains in the stomach for 3-4 hours. The food is broken down physically by being churned by the muscles in the stomach wall and is also broken down by enzymes.

24
Q

Structure of the stomach

A

The stomach wall contains gastric glands, which produce HCL (hydrochloric acid), enzymes and mucus.

25
Q

pH in the stomach

A

The stomach has a pH of 1 or 2, this kills bacteria in the stomach and is the optimum pH for pepinogen and pepsin (enzymes).
Ex. Gastric protease – Long proteins – Polypeptides.

26
Q

Function of Mucus

A

Protects the stomach wall from HCL and enzymes.

27
Q

Define Chyme

A

The food that is converted to a creamy liquid.

28
Q

What is the Pyloric Sphincter Muscle?

A

It relaxes and food passes through into the duodenum, which is a component of the small intestine.

29
Q

The Small Intestine

A

It is a narrow muscular tube. It is 8m long. The main functions are absorption and the further digestion of food.

30
Q

Structure of the Small Intestine

A

The internal surface of the small intestine is folded, the surface of which is covered by thousands of villi.
The small intestine consists of two parts: Duodenum and Ileum

31
Q

Function of Villi

A

Villi increase the surface area of the small intestine and release of enzymes.

32
Q

Lymph Vessels

A

Capillaries in the lymph vessel absorb glucose and amino acids in the bloodstream.
Lymph Vessels mainly absorb fat.
They have the same structure in the stomach wall, duodenum an ileum.

33
Q

Duodenum

A

Food entering this region of the small intestine is mixed with juices from three regions.

34
Q
  1. Pancreatic Juices
A
  • Fluid enters the duodenum through the pancreatic duct.
  • Consists of sodium bicarbonate (neutralises acidic chyme) and pancreatic enzymes.
  • Pancreatic Amylase, Pancreatic Protease, Pancreatic Lypase
  • Starch, Protein, Lipids
  • Maltose, Peptides, Triglycerol
35
Q

Functions of the Ileum

A

The ileum has two functions: Absorption and further digestion by peristalsis.
- villi - micro-villi - lacteal - capillaries.

36
Q

The Ileum

A

Food can remain here for up to six hours and is churned (physical digestion) with enzymes. Enzymes are secreted from the walls of the ileum to complete digestion.

37
Q

Enzymes in the ileum

A
  1. Maltase - Maltose - Glucose
  2. Peptidase - Peptides - Amino Acids
  3. Lipase - Lipids - Triglyceride.
38
Q

Fibre

A

Cellulose/Fibre cannot be digested by human enzymes. The function of fibre in digestion is that it stimulates peristalsis and prevents constipation. It passes through the alimentary canal unchanged.

39
Q

What are the main nutrients of absorption?

A 
Carbohydrates
Proteins
Lipids
Minerals 
Vitamins 
Water
40
Q

Absorption and digestion in the Ileum

A
  • Carbohydrates - Monosaccharides- Capillaries- Liver
  • Protein - Amino acids - Capillaries - Liver
  • Lipids - 3 fatty acids and a glycerol- lacteal- lymph vessel- left sub-clavian vein - Blood.
  • Viamins- Vitamin - Capillaries - Liver
  • Minerals -Minerals - Capillaries - Liver
  • Water-Water- Capillaries -Liver

5th Year Biology (5 decks)

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