Nutrition Flashcards

1
Q

Define autotroph

A

Organisms that use simple inorganic molecules to create complex organic molecules

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2
Q

Define heterotroph

A

Organisms that consume complex organic food material

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3
Q

GIve the three types of heterotroph and their definitions

A

Holozoic feeders follow the process of ingestion, digestion, absorption, assimilation and egestion. Parasites live in or on a host organism and cause it harm. Saprophytes feed by extracellular digestion

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4
Q

Why do we have a tube gut?

A

Because we have a varied diet each part is specialised to digest/absorb different molecules

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5
Q

From the outside in, what are the layers that make up the gut wall?

A

Serosa, longitudinal muscle layer, circular muscle layer, submucosa and mucosa

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6
Q

What digestion occurs in the mouth?

A

Chemical digestion of starch by amylase, mechanical digestion by chewing

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7
Q

How is food moved down the oesophagus?

A

Peristalsis- circular muscles contract and longitudinal muscles relax to push the food bolus along

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8
Q

What digestion occurs in the stomach?

A

Chemical digestion of proteins by the enzyme pepsin to shorter chains. Mechanical digestion by churning

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9
Q

Which cells produce pepsinogen in the stomach?

A

Chief cells (/zymogen cells)

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10
Q

Which cells produce HCl in the stomach?

A

Oxyntic cells (/parietal cells)

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11
Q

What are the purposes of HCl in the stomach?

A

To activate pepsinogen to pepsin, to kill bacteria and to give the optimum pH for pepsin enzyme

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12
Q

Why is pepsinogen released in inactive form in the stomach and how is it activated?

A

Otherwise it would cause autolysis (digest the cells making it). It is activated by HCl

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13
Q

What are endo and exopeptidases?

A

Endopeptidases hydrolyse peptide bonds in the middle of a polypeptide chain, exopeptidases at the terminal ends

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14
Q

Which enzymes are produced by the pancreas?

A

Trypsin (endopeptidase), exopeptidases, lipase, amylase

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15
Q

What is the function of bile and where is it produced/stored

A

Emulsifies lipids to increase surface area for lipase. Made in liver, stored in gall bladder

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16
Q

Why is trypsinogen released in inactive form and how is it activated?

A

Otherwise it would cause autolysis (digest the cells making it). It is activated by enterokinase, also from the pancreas

17
Q

Which enzymes are fixed within the cell membrane of the epithelial cells in the duodenum and ileum to digest dimers intracellularly?

A

Lactase, sucrase, maltase and dipeptidase

18
Q

How are glucose and amino acids absorbed in the ileum?

A

Co transport with sodium ions

19
Q

How are lipids absorbed in the ileum?

A

Triglycerides have been broken down into fatty acids and glycerol, which can diffuse through the phospholipid bilayer

20
Q

What happens to glucose after it is absorbed in the ileum?

A

They enter capillaries by facilitated diffusion then transported via hepatic portal vein to the liver. Used for protein synthesis or deaminated

21
Q

What happens to amino acids after they are absorbed in the ileum?

A

They enter capillaries by facilitated diffusion then transported via hepatic portal vein to the liver. Used for respiration or stored as glycogen

22
Q

What happens to lipids after they are absorbed in the ileum?

A

Reassembled into triglycerides at SER. These then pass into the lacteal and are carried via the lymphatic system to the blood at the thoracic duct

23
Q

Why do we need to eat fibre?

A

Cellulose fibre is required to provide bulk to faeces and stimulate peristalsis.

24
Q

What is the function of the colon?

A

Absorbs the remaining water, together with vitamins

25
Q

Give the function of incisors, molars and diastema in herbivores

A

Sharp incisors snip off vegetation against horny pad, molars are ridged for grinding, diastema allows tongue to manipulate food

26
Q

Give the function of incisors, canines, carnassials and molars in carnivores

A

Sharp incisors strip meat from bone, canines grip/kill prey, carnassials are like scissors for slicing flesh/crushing bones, molars for cutting

27
Q

Why are herbivore guts longer than carnivore guts?

A

Protein and fat are easier to digest than cellulose, so need less time and enzyme action. Plant matter has less nutrients so herbivores must eat more

28
Q

List the four chambers of a ruminant gut

A

Rumen, reticulum, omasum, abomasum

29
Q

How are headlice adapted to be ectoparasites?

A

They have claws which hold onto the hairs and lays eggs which are glued to the base of hairs

30
Q

How has a tapeworm adapted to living in a human gut?

A

Thick cuticle, produces anti-enzymes, scolex has hooks and suckers to attach to the gut wall, reduced gut, produces large number of eggs