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Biology 1 > Lecture 19 and 20- Digestion and absorption > Flashcards

Lecture 19 and 20- Digestion and absorption Flashcards

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1
Q

What organisms are autotrophs?

A

Most plants,

Some archaea, bacteria and protists

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2
Q

What are autotrophs?

A

Organisms that synthesise their own necessary nutrients from inorganic compounds

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3
Q

What do heterotrophs depend on?

A

Organic synthesis carried out by autotrophs to derive their own nutrients

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4
Q

What have heteotrophs evolved to exploit autotroph resources?

A

Adaptations

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5
Q

What is a calorie?

A

A unit of heat energy

1 calorie is the energy needed to raise one gram of water by one degree celsius

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6
Q

What many calories are their in a Joule?

A

0.239 calories = 1 J

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7
Q

What is the metabolic rate of an animal a measure of?

A

The energy needs of an animal that are met by food intake and digestion

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8
Q

What are energy budgets constructed with?

A

Calories consumed

Calories expended

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9
Q

What is the basal metabolic rate for the average human adult female?

A

1300-1500kcal per day

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10
Q

What is the basal metabolic rate for the average human adult male?

A

1600-1800 kcal per day

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11
Q

What do energy budgets show?

A

How animals use their resources. Cost- benefit model can be applied to analyse behavior.

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12
Q

Give an example of territorial behavior.

A

African sunbirds feed on the specific nectar

The birds are only territorial if the food resource was rich enough to support cost of aggressive behavior.

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13
Q

How is food stored between meals?

A

Carbohydrates as glycogen in muscle and liver

Fat stores

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14
Q

How much energy is stored in glycogen?

A

About 1 days worth of basal energy requirments

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15
Q

What is the advantage of storing energy as fat rather than glycogen?

A

More energy per gram- little water- more compact.

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16
Q

What can be metabolised for energy but is not used as a energy storage compound?

A

Protein

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17
Q

What is undernourishment?

A

Too little food taken in. Body metabolises its own molecules.

  • Protein is lost rapidly to protein synthesis
  • Glycogen and fat are broken down
  • Decreased protein use
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18
Q

What can decreased protein cause?

A

Edema- a sign of kwashiorkor

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19
Q

What is kwashiorkor?

A

Caused by chronic protein deficiency

Protein synthesis in the liver stops, decreased blood proteins, fluid enters the interstital spaces

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20
Q

What is overnourishment?

A

More food is taken in than needed and stored as increased body mass

  • Glycogen reserves are built
  • Extra molecules are converted to body fat
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21
Q

What molecule do animals derive from the metabolsim of most food?

A

The acetyl group, CH3CO-

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22
Q

What is the acetyl group used for?

A

Supply carbon skeleton and build complex molecules

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23
Q

What are amino acids used for?

A

Building blocks of proteins

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24
Q

What name is given to amino acids that cannot be synthesized in the human body?

A

Essential amino acids (8 in humans)

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25
Q

Why are proteins digested before being used in the body?

A
  • Proteins are not easily absorbed by the gut
  • Protein structure/function vary by species (not optimal)
  • Immune system would attack protein molecules entering the gut
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26
Q

What name is given to fats that cannot be synthesized by an organism?

A

Essential fatty acids

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27
Q

What essential fatty acid do humans require?

A

Linoleic acid

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28
Q

What is linoleic acid used for?

A

Synthesize other unsaturated fatty acids

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29
Q

Other than essential fatty acids and amino acids, what must an animal derive from their diets?

A

Macronutrients
Micronutrients
Vitamins

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30
Q

Name some macronutrients

A

Calcium, chlorine, magneisum

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31
Q

Name some micronutrients

A

Iron, iodine, chromium, fluorine

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32
Q

What are vitamins?

A

Carbon compounds that cannot be synthesized

  • Species specific
  • Water or fat soluble
  • 13 in total
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33
Q

What is calcium used for?

A

Calcium phosphate is the principle structural material in teeth and bones
Muscle contraction, neuronal function and other intracellular functions

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34
Q

What does nutrient deficiencies lead to?

A

Malnutrition

Chronic malnutrition leads to deficiency disease

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35
Q

What causes scurvy?

A

Lack of vitamin C

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36
Q

What causes anemia?

A

Lack of iron (oxygen-binding)

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37
Q

What does vitamin D do and what can a deficiency lead to?

A

Helps to absorb phosphate and calcium

Rickets

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38
Q

How else can a deficiency be acquired?

A

Inability to absorb a nutrient

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39
Q

What is pernicious anemia?

A

Vitamin B12 is not absorbed in the stomach

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40
Q

What are the 5 adaptations animals have to feed?

A 
Mechanical
Biochemical
Physiological
Behavioral
Microbial
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41
Q

How have herbivores adapted to eating difficult to digest, low energy content food?

A
  • Spend a long time feeding

- Physical adaptations- elephant trunk, giraffe neck, mouthparts in invertebrates, tooth shape

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42
Q

How have carnivores adapted to ingest and digest food?

A

-Adaptations to detect, capture, kill and ingest prey

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43
Q

What adaptation have bats evolved to aid obtaining food?

A

Echolocation

44
Q

What adaptation have snakes evovled to aid obtaining food?

A

Jacobson’s organ, hinged jaw, venom

45
Q

What are the three layers of the general mammalian tooth?

A
  • Enamel
  • Dentine
  • Pulp cavity
46
Q

What is the enamel of a tooth?

A

Composed of calcium phosphate

Covers crown of tooth

47
Q

What is the dentine of a tooth?

A

A layer between the crown and root

48
Q

What is the pulp cavity?

A

A layer within the dentine

Contains blood vessels, nerves, cells that produce dentine

49
Q

What are the 4 types of tooth?

A

Canines
Incisors
Premolars
Molars

50
Q

What are canines used for?

A

Ripping and tearing

51
Q

What are incisors used for?

A

Cutting

52
Q

What are premolars used for?

A

Shearing

53
Q

What are molars used for?

A

Grinding

54
Q

What is the simplest digestive system?

A

A gastrovascular cavity- seen in cnidarians

55
Q

How do animals digest their food?

A

Extracellularly

56
Q

What are tubular guts?

A

A mouth takes in food, waste is eliminated through an anus. Different regions of the gut are specialized

57
Q

How is food broken up at the anterior end of the gut?

A

Teeth in vertebrates
Radula in snails
Mandibles in arthropods
Birds- stones in the gizzard

58
Q

What are storage chambers that allow for gradual digestion?

A

Stomachs and crops

59
Q

Where are most nutrients, water and ions absorbed?

A

Midgut

60
Q

What is the function of the hindgut?

A

To recover ions and water

Store feces

61
Q

What helps with the expulsion of feces?

A

Muscular rectum near anus

62
Q

What lives in the hindgut of many species?

A

Colonies of endosymbiotic bacteria

63
Q

What is the role of endosymbiotic bacteria in the hindgut?

A

Help break down food

Such as in leeches

64
Q

What other adaptations are there to increase absorbance efficiency in animal guts?

A
  • Increased surface area: folds called villi, microvilli
  • Slow food passage using cecal or spiral valves
  • Long intestine
65
Q

What adaptations have worms evolved to increase gut surface area?

A

Longitudinal infolding of intestinal wall

66
Q

What do proteases break down?

A

Bonds between amino acids

67
Q

What enzymes break down fats?

A

Lipases

68
Q

What enzymes break down peptides?

A

Peptidases

69
Q

What is zymogen?

A

Inactive form of digestive enzymes- cannot act on cell that produced it

70
Q

What happens when zymogen is secreted into the gut?

A

It is activated by another enzyme

71
Q

Why is the cell lining of the gut not digested?

A

It is protected by a mucus covering.

72
Q

What is in the rumen and reticulum of a ruminant’s stomach?

A

Abundant cellulose-fermenting microorganisms

73
Q

What happens to the contents of the rumen periodically?

A

Regurgitated for rechewing

74
Q

Where does the fermented food pass into next?

A

The omasum

Where it is concentrated by water absorption

75
Q

Where does the contents of the omasum pass next?

A

The abomasum- the true stomach

76
Q

What is digestion governed by?

A

Neuronal and hormonal control

77
Q

What responses are unconscious reflexes?

A

Swallowing, salivating

78
Q

What do unconscious reflexes do?

A

Coordinate digestion

79
Q

What type of nervous system does the digestive tract have?

A

Independent (intrinsic) nervous system
Neuronal messages do not have to be processed by the CNS
(Parasympathetic nervous system)

80
Q

What is secretin?

A

Produced in the duodenum

Causes pancreas to secrete digestive juices

81
Q

What enzyme in the small intestine causes the gall bladder to release bile, stimulates the pancreas, slows stomach and release digestive enzymes>

A

Cholecytokinin

82
Q

What is cholecytokinin released in response to?

A

Undigested fats and proteins in the chyme

83
Q

What hormone is secreted by the stomach?

A

Gastrin

84
Q

What is gastrin released into?

A

The blood

85
Q

What gastrin stimulate?

A

Stimulates secretion of HCl and pepsin and increases motility of stomach

86
Q

What is the absorptive state?

A

The period following a meal when food is in the gut and nutrients are being absorbed

87
Q

What is the post absorptive period?

A

Stomach and small intestine are empty, body metabolism relies on internal energy reserves

88
Q

What is gluconeogenesis?

A

Conversion of amino acids and other molecules into glucose in the liver

89
Q

What is the function of a lipoprotein?

A

Aid fat transport in the blood

90
Q

What is the structure of a lipoprotein?

A

Hydrophobic fat core covered by a hydrophilic protein

91
Q

What are the largest lipoproteins in the blood?

A

Chylomicrons (produced in the intestine)

92
Q

How does the liver control fat metabolsim?

A

Production of lipoproteins

93
Q

How are lipoproteins classified?

A

According to density
Fat- low density
Protein- high density

94
Q

What is the function of high density lipoproteins?

A

Remove cholesterol from tissues and carry to liver to synthesize bile

95
Q

What is the composition of HDL’s?

A

50% protein
35% lipid
15% cholestrol

96
Q

What is the function of LDLs?

A

Transport cholesterol around body for biosynthesis and storage

97
Q

What is the function of very low density lipoproteins?

A

Contain mostly triglyceride fats, transport to fat cells in adipose tissues

98
Q

What hormones control fuel metabolism?

A

Insulin and glucagon.

99
Q

When is insulin released by the pancreas?

A

During the absorptive period when blood glucose rises

100
Q

What does insulin do?

A

Promotes uptake and utilisation or storage of glucose and glycogen

101
Q

Where does insulin act?

A

Skeletal muscle, adipose tissue, liver

102
Q

What happens when glucose in blood falls?

A

Glucagon is released- liver breaks down glycogen and begins gluconeogenesis

103
Q

What part of the brain controls food intake?

A

The hypothalamus

104
Q

What does the hypothalamus do?

A

Provides signals on hunger or satiety and governs how much food is eaten

105
Q

What hormone does the stomach release to govern hunger?

A

Ghrelin promotes hunger

106
Q

What hormone provides feedback information to the brain about body fat reserves?

A

Leptin

107
Q

What produces leptin?

A

Body fat cells

Biology 1 (16 decks)

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