Nutrition In Humans Flashcards

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0
Q

Name the parts in the alimentary canal.

A
  1. Mouth and buffalo cavity
  2. Pharynx
  3. Oesophagus
  4. Stomach
  5. Small intestine
  6. Large intestine
  7. Anus
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1
Q

What is assimilation?

A

Conversation of absorbed food materials to provide energy or to form new protoplasm.

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2
Q

What is the function of taste buds on the tongue?

A

Aid in detecting and selecting food.

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3
Q

What is the function of the pharynx?

A

Common passage for air and food. Air moves into trachea while food substances move into oesophagus.

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4
Q

What is the epiglottis?

A

Flap like cartilage situated above larynx and just behind tongue which prevents food substances from entering trachea during swallowing.

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5
Q

How does coughing occur?

A

In the event that food particles or droplets of water, automatic violent coughing reaction to expel food particles or water droplets to prevent choking.

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6
Q

Which is the only section in the alimentary canal without any muscles?

A

Pharynx.

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7
Q

The walls of the alimentary canal is made up of which layers?

A

Except in anus.

  1. Serous coat
  2. Muscular layer
  3. Submucous coat
  4. Mucous layer
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8
Q

The wall of the oesophagus contains which 2 layers?

A
  1. Longitudinal muscles on outer sides of gut wall.

2. Circular muscles on inner sides of gut wall.

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9
Q

What is peristalsis?

A

Rhythmic, wave like contractions of alimentary canal wall to move food along alimentary canal.

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10
Q

What is peristalsis brought about by?

A

Dilation and constriction.

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11
Q

Describe the structure of the stomach.

A

Distensible muscular bag with thick and well developed muscular walls.

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12
Q

What is the function of the pyloric sphincter?

A
  1. contracts to cause opening to small intestine to close and hence no food particles can pass through.
  2. Relaxation will allow food to enter small intestine.
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13
Q

How is gastric juice produced?

A

Food in stomach stimulates secretion of gastric juices into stomach cavity by gastric glands.

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14
Q

What does the small intestine consists of ?

A

U- shaped duodenum, jejunum and highly coiled ileum.

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15
Q

How long is the small intestine?

A

About 6 meters.

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16
Q

What are mesenteries?

A

Thin, transparent membranes attaching small intestine to dorsal body wall.

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17
Q

How does the small intestine secrete digestive enzymes?

A

Lining of walls contains glands that secrete digestive enzymes.

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18
Q

How is the small intestine adapted to absorb digested materials?

A

Through presence of villi and microvilli.

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19
Q

What are the 3 glands associated with the small intestine?

A
  1. Liver
  2. Gall bladder
  3. Pancreas
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20
Q

Which blood vessels are attached to the lower surface of the liver?

A
  1. Hepatic portal vein.
  2. Hepatic vein.
  3. Hepatic artery.
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21
Q

What is the function of the liver?

A

Produce and secret bile.

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22
Q

What does bile contain?

A

It is an alkaline greenish yellow liquid containing bile salts and bile pigments.

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23
Q

What are bile pigments?

A

Waste products from breakdown of haemoglobin and these are removed with faeces.

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24
Q

What is the function of bile?

A

Does not contain enzymes, aid in fat digestion.

25
Q

What is the gall bladder and what is it’s function?

A

Store bile temporarily, it’s a greenish yellow bag attached to the liver.

26
Q

How is bile released from the gall bladder?

A

Bile releases into duodenum through bile duct upon contraction of gall bladder walls.

27
Q

What is the function of the pancreas?

A
  1. Secrete pancreatic juices containing: amylase, lipase and trysinogen(a protease).
  2. Secretes insulin and glucagon, plays part in controlling concentration of glucose in blood and carbohydrate metabolism.
28
Q

What does the long intestine consists of and how long is it?

A

About 1.5m long.

Consists of: caecum and appendix, colon, and rectum.

29
Q

What is the function of the caecum and appendix?

A

In humans, caecum and appendix have no specific function. Appendix can become infected and inflamed, causing appendicitis.

30
Q

What is the rectum?

A

Muscular tube where faeces at stored temporarily.

31
Q

What is the main function of the stomach?

A

Muscular walls churn and help break down food further( physical and chemical digestion), and gastric juice mixes with food to form chyme.

32
Q

What is the main function of the colon?

A

Absorb water and mineral salts from undigested food materials.

33
Q

What is the caecum?

A

Junction between small intestine and large intestine.

34
Q

How are the faeces expelled?

A

Through anus with contraction of recall wall.

35
Q

What happens to food in the mouth?

A
  1. Food mixed with saliva, softened by mucin.
  2. Mastication breaks down food into smaller pieces(increase SA).
  3. Amylase, present in saliva, digests starch to maltose.
36
Q

How is the bolus passed down the oesophagus?

A

Through gravity and peristalsis.

37
Q

What does the gastric juice contain?

A
  1. Dilute solution of Hydrochloric acid( pH2)
  2. Prorenin
  3. Pepsinogen
38
Q

What happens in the stomach?

A

Peristaltic movement in stomach churns food and mixes it well with gastric juice(as well as to break down food substances into smaller pieces.)

39
Q

What are the functions of Hydrochloric acid?

A
  1. Stops action of salivary amylase.
  2. Converts inactive forms of gastric enzymes to active forms, from pepsinogen to pepsin and from prorenin to renin.
  3. Provides acidic medium for action of digestive enzymes.
  4. Kills germs and potential parasites.
40
Q

What happens if there is excess Hydrochloric acid?

A

May erode stomach walls and hence results in gastric ulcers.

41
Q

What is the function of pepsin?

A

Causes breakdown of proteins to peptones or polypeptides.

42
Q

Why does pepsin need to be formed in the inactive state?

A

They will breakdown the proteins found in cells that produces them.

43
Q

What is the function of renin?

A

Convert soluble protein caeseinogen into insoluble caesin, process that requires calcium ions. Insoluble caesin remain long enough to be digested by pepsin.

44
Q

Where is protein digestion completed?

A

Ileum.

45
Q

The presence of chyme in the small intestine stimulates?

A
  1. Secretion of intestinal juice(contains enterokinase, erepsin, maltase, sucrase, lactase and intestinal lipase by intestinal glands)
  2. Secretion of pancreatic juice( amylase, lipase, trypsinogen, in give form of protease)
  3. Release of bile
46
Q

How is acidic chyme neutralized, and what is the purpose of neutralization?

A
  1. Acidic chyme comes into contact with intestinal juice, pancreatic juice and bile( all alkaline in nature) and is neutralized.
  2. Alkaline environment created to provide suitable alkaline medium for action of pancreatic and intestinal enzymes.
47
Q

Explain the digestion of starch in the small intestine.

A
  1. Minimal(amt of time food is in mouth compared with other parts of alimentary canal).
  2. Remaining starch entering SI digested by pancreatic amylase to maltose, then to glucose by maltase.
48
Q

Explain the fat digestion in the small intestine.

A
  1. Bile emulsifiers fats by breaking up fat into minute fat globules suspended in water to form stable emulsion.
  2. Emulsification increases surface area of fats for digestion.
  3. Emulsified fats converted by lipases to fatty acid and glycerol.
49
Q

Explain the protein digestion in the small intestine.

A
  1. Some protein digestion occurs in stomach.
  2. Undigested proteins in small intestine converted by trypsin to peptones, which are converted by erepsin to amino acids.
50
Q

How is the small intestine adapted for absorption?

A
  1. Inner walls of SI thrown into many transverse folds.
  2. Villi and microvilli increase SA.
  3. Long length of SI
  4. Epithelium one cell thick.
51
Q

What is the lacteal?

A

A lymphatic vessel present in villi which is surrounded by blood capillaries. Aid in transport of fat.

52
Q

What is egestion/ defaecation?

A

Removal of undigested matter from body.

53
Q

Why are fats broken down into glycerol and fatty acids?

A
  1. Glycerol soluble in water and diffuses through epithelium.
  2. Fatty acids react with bile salts to form soluble soaps so it can diffuse through epithelium.
  3. In epithelium, glycerol and soluble salts recombine to form minute fat globules which are absorbed by lacteals.
54
Q

What happens to the water soluble substances after being absorbed into small intestine? (Amino acids, sugars, minerals, vitamins)

A
  1. They enter blood vessels which unite to form larger blood vessels.
  2. These in then unite to form hepatic portal vein.
  3. HPV transports nutrients to liver.
55
Q

What happens to the fats after being absorbed into lacteals?

A
  1. Fats absorbed into lymphatic capillaries.
  2. Lymphatic capillaries join to form larger lymphatic vessels, which discharge fats into bloodstream.
  3. Blood carries fats to all parts of body, especially liver.
56
Q

Where is excess fat stored in?

A

Adipose tissues. - A layer of tissues beneath skin, around heart, kidneys and in mesenteries binding intestines, where fats are stored.

57
Q

What are the functions of the liver?

A
  1. Production of bile
  2. Regulation of blood glucose conc.
  3. Storage of glycogen.
  4. Deamination of excess amino acids.
  5. Iron storage.
  6. Detoxification
58
Q

How are amino acids deaminated by the liver?

A
  1. Amino group converted into urea and removed from body in urine.
  2. Remains of deaminated amino acids converted to glucose in liver.
59
Q

How is iron stored in the liver?

A
  1. Red blood cells become worn out after period of time and destroyed by spleen.
  2. Haemoglobin of red blood cells brought back to liver where it is broken down and iron releases it stored.