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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
Why are proteins digested before being used in the body?
- 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
26
What name is given to fats that cannot be synthesized by an organism?
Essential fatty acids
27
What essential fatty acid do humans require?
Linoleic acid
28
What is linoleic acid used for?
Synthesize other unsaturated fatty acids
29
Other than essential fatty acids and amino acids, what must an animal derive from their diets?
Macronutrients Micronutrients Vitamins
30
Name some macronutrients
Calcium, chlorine, magneisum
31
Name some micronutrients
Iron, iodine, chromium, fluorine
32
What are vitamins?
Carbon compounds that cannot be synthesized - Species specific - Water or fat soluble - 13 in total
33
What is calcium used for?
Calcium phosphate is the principle structural material in teeth and bones Muscle contraction, neuronal function and other intracellular functions
34
What does nutrient deficiencies lead to?
Malnutrition | Chronic malnutrition leads to deficiency disease
35
What causes scurvy?
Lack of vitamin C
36
What causes anemia?
Lack of iron (oxygen-binding)
37
What does vitamin D do and what can a deficiency lead to?
Helps to absorb phosphate and calcium | Rickets
38
How else can a deficiency be acquired?
Inability to absorb a nutrient
39
What is pernicious anemia?
Vitamin B12 is not absorbed in the stomach
40
What are the 5 adaptations animals have to feed?
``` Mechanical Biochemical Physiological Behavioral Microbial ```
41
How have herbivores adapted to eating difficult to digest, low energy content food?
- Spend a long time feeding | - Physical adaptations- elephant trunk, giraffe neck, mouthparts in invertebrates, tooth shape
42
How have carnivores adapted to ingest and digest food?
-Adaptations to detect, capture, kill and ingest prey
43
What adaptation have bats evolved to aid obtaining food?
Echolocation
44
What adaptation have snakes evovled to aid obtaining food?
Jacobson's organ, hinged jaw, venom
45
What are the three layers of the general mammalian tooth?
- Enamel - Dentine - Pulp cavity
46
What is the enamel of a tooth?
Composed of calcium phosphate | Covers crown of tooth
47
What is the dentine of a tooth?
A layer between the crown and root
48
What is the pulp cavity?
A layer within the dentine | Contains blood vessels, nerves, cells that produce dentine
49
What are the 4 types of tooth?
Canines Incisors Premolars Molars
50
What are canines used for?
Ripping and tearing
51
What are incisors used for?
Cutting
52
What are premolars used for?
Shearing
53
What are molars used for?
Grinding
54
What is the simplest digestive system?
A gastrovascular cavity- seen in cnidarians
55
How do animals digest their food?
Extracellularly
56
What are tubular guts?
A mouth takes in food, waste is eliminated through an anus. Different regions of the gut are specialized
57
How is food broken up at the anterior end of the gut?
Teeth in vertebrates Radula in snails Mandibles in arthropods Birds- stones in the gizzard
58
What are storage chambers that allow for gradual digestion?
Stomachs and crops
59
Where are most nutrients, water and ions absorbed?
Midgut
60
What is the function of the hindgut?
To recover ions and water | Store feces
61
What helps with the expulsion of feces?
Muscular rectum near anus
62
What lives in the hindgut of many species?
Colonies of endosymbiotic bacteria
63
What is the role of endosymbiotic bacteria in the hindgut?
Help break down food | Such as in leeches
64
What other adaptations are there to increase absorbance efficiency in animal guts?
- Increased surface area: folds called villi, microvilli - Slow food passage using cecal or spiral valves - Long intestine
65
What adaptations have worms evolved to increase gut surface area?
Longitudinal infolding of intestinal wall
66
What do proteases break down?
Bonds between amino acids
67
What enzymes break down fats?
Lipases
68
What enzymes break down peptides?
Peptidases
69
What is zymogen?
Inactive form of digestive enzymes- cannot act on cell that produced it
70
What happens when zymogen is secreted into the gut?
It is activated by another enzyme
71
Why is the cell lining of the gut not digested?
It is protected by a mucus covering.
72
What is in the rumen and reticulum of a ruminant's stomach?
Abundant cellulose-fermenting microorganisms
73
What happens to the contents of the rumen periodically?
Regurgitated for rechewing
74
Where does the fermented food pass into next?
The omasum | Where it is concentrated by water absorption
75
Where does the contents of the omasum pass next?
The abomasum- the true stomach
76
What is digestion governed by?
Neuronal and hormonal control
77
What responses are unconscious reflexes?
Swallowing, salivating
78
What do unconscious reflexes do?
Coordinate digestion
79
What type of nervous system does the digestive tract have?
Independent (intrinsic) nervous system Neuronal messages do not have to be processed by the CNS (Parasympathetic nervous system)
80
What is secretin?
Produced in the duodenum | Causes pancreas to secrete digestive juices
81
What enzyme in the small intestine causes the gall bladder to release bile, stimulates the pancreas, slows stomach and release digestive enzymes>
Cholecytokinin
82
What is cholecytokinin released in response to?
Undigested fats and proteins in the chyme
83
What hormone is secreted by the stomach?
Gastrin
84
What is gastrin released into?
The blood
85
What gastrin stimulate?
Stimulates secretion of HCl and pepsin and increases motility of stomach
86
What is the absorptive state?
The period following a meal when food is in the gut and nutrients are being absorbed
87
What is the post absorptive period?
Stomach and small intestine are empty, body metabolism relies on internal energy reserves
88
What is gluconeogenesis?
Conversion of amino acids and other molecules into glucose in the liver
89
What is the function of a lipoprotein?
Aid fat transport in the blood
90
What is the structure of a lipoprotein?
Hydrophobic fat core covered by a hydrophilic protein
91
What are the largest lipoproteins in the blood?
Chylomicrons (produced in the intestine)
92
How does the liver control fat metabolsim?
Production of lipoproteins
93
How are lipoproteins classified?
According to density Fat- low density Protein- high density
94
What is the function of high density lipoproteins?
Remove cholesterol from tissues and carry to liver to synthesize bile
95
What is the composition of HDL's?
50% protein 35% lipid 15% cholestrol
96
What is the function of LDLs?
Transport cholesterol around body for biosynthesis and storage
97
What is the function of very low density lipoproteins?
Contain mostly triglyceride fats, transport to fat cells in adipose tissues
98
What hormones control fuel metabolism?
Insulin and glucagon.
99
When is insulin released by the pancreas?
During the absorptive period when blood glucose rises
100
What does insulin do?
Promotes uptake and utilisation or storage of glucose and glycogen
101
Where does insulin act?
Skeletal muscle, adipose tissue, liver
102
What happens when glucose in blood falls?
Glucagon is released- liver breaks down glycogen and begins gluconeogenesis
103
What part of the brain controls food intake?
The hypothalamus
104
What does the hypothalamus do?
Provides signals on hunger or satiety and governs how much food is eaten
105
What hormone does the stomach release to govern hunger?
Ghrelin promotes hunger
106
What hormone provides feedback information to the brain about body fat reserves?
Leptin
107
What produces leptin?
Body fat cells

Biology 1 (16 decks)

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