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Post-absorptive Mechanisms Flashcards

1
Q

Absorptive state

A

During which ingested nutrients enter the blood from GI tract
Ingested, circulating nutrients provide the energy requirements
Excess is stored in post-absorptive state

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2
Q

Post-absorptive state

A

GI tract is empty
Nutrients come from body stores

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3
Q

How long can glycogen stores last

A

12 hours

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4
Q

How long can lipid stores last

A

3 months

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5
Q

When is tissue protein used as an energy source

A

After prolonged starvation

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6
Q

Which 2 organs require 40% of energy requirement at rest

A

Brain and liver

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7
Q

Energy requirements of brain

A

Glucose
Keton bodies

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8
Q

Energy requirements of muscle

A

Glucose, triacylglycerol, branched chain amino acids
Ketone bodies (at rest)

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9
Q

Energy requirements of liver

A

Amino acids
Fatty acids
Glucose
Alcohol

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10
Q

Why can’t ketone bodies be used by the liver

A

Produced here but have no thiolase

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11
Q

Energy requirements of kidney cortex

A

Glucose
Ketone bodies

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12
Q

Energy requirements of kidney medulla

A

Glucose

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13
Q

Energy requirements of small intestine

A

Ketone bodies (in starvation)
Glutamine

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14
Q

Energy requirements of large intestine

A

Short chain fatty acids
Glutamine

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15
Q

BMI and health

A

As BMI goes up mortality increases exponentially
Cancer/ heart disease/ musculoskeletal/ sleep apnea

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16
Q

Fed state

A

Fuels are oxidised to energy
Any excess is stored
Triglycerides in adipose
Glycogen in muscle or liver
Limited amount to how much glycogen can be stored in muscle and liver so more is converted into adipose

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17
Q

Insulin and the liver

A

Glucose to liver
Insulin promotes uptake of glucose into cells for storage as glycogen
Some glucose used to produce energy

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18
Q

Glucose and liver

A

Stored as glycogen
Used to produce energy = converted to acetyl-CoA to enter kreb’s cycle

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19
Q

Acetyl-CoA and liver

A
  1. Enters kreb’s cycle to produce ATP
  2. Make triglycerides that enter bloodstream as VLDLs
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20
Q

VLDLs

A

Very low density lipoprotein
Triglycerides that enter bloodstream from liver
High glucose = high VLDL levels

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21
Q

Glucose and erythrocytes

A

Glucose taken up but cannot be stored
Glucose converted to pyruvate which can diffuse out of cell or be converted into lactate
Lactate is released from the cell

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22
Q

Post-absorptive state and amino acids

A

Absorption through intestines
Converted into proteins (can be reversed)
Can make hormones and other molecules
Feed into kreb’s cycle to make ATP

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23
Q

Where are amino acids absorbed

A

Intestines

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24
Q

Glucose and adipocytes

A

Glucose taken up (promoted by insulin)
Used to make ATP or stored as triglycerides

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25
Glucose and muscle
Glucose stored as glycogen Uses insulin to promote uptake
26
Lipoproteins
LDL HDL VLDL
27
Absorption of triglycerides
Chylomicrons carry triglycerides and lipoproteins Into the lymphatic system and then blood stream
28
Glucose and CNS
Converted to acetyl-CoA Enters kreb’s cycle No energy stored in brain
29
Fasting state
Maintaining blood glucose whilst not eating Body breaks down its energy stores Horus to overnight
30
Pathway of glucose
Broken down and absorbed in intestines Passes through blood in liver Reaches muscles, brain, erythrocytes and adipocytes
31
Pancreas
Endocrine and exocrine organ
32
Where is insulin produced
Pancreas
33
Where is glucagon produced
Pancreas
34
Insulin
Main anabolic hormone Energy uptake into cells Glycogen storage, fat storage and protein synthesis
35
Glucagon
Main catabolic hormone Energy release Glycogenolysis, gluconeogenesis, ketogenesis
36
Where is cortisol produced
Adrenal gland
37
Where is adrenaline/noradrenaline produced
Adrenal gland
38
Cortisol
Preparation for stress response Lipolysis, protein breakdown, gluconeogenesis, glycogen storage
39
Adrenaline/noradrenaline
Fight or flight Energy into blood stream to be used Glycogenolysis, gluconeogenesis, lipolysis
40
Where is thyroxine produced
Thyroid gland
41
Thyroxine
Generally controls metabolism Glycolysis, cholesterol synthesis, glucose uptake, protein synthesis, sensitises tissues to adrenaline
42
Where is growth hormone produced
Pituitary gland
43
Where is somatostatin produced
Pituitary gland
44
Growth hormone
Gluconeogenesis, glycogen synthesis, lipolysis, protein synthesis, decreased glucose use
45
Which hormones trigger Glycogenolysis
Glucagon Adrenaline/noradrenaline
46
Which hormones trigger gluconeogenesis
Glucagon Cortisol Adrenaline/noradrenaline Growth hormone
47
Which hormones trigger glycogen storage
Insulin Cortisol Growth hormone
48
What 2 hormones control appetite
Leptin and ghrelin
49
Where is leptin released from
Adipocytes
50
Where is ghrelin released from
Stomach
51
What does leptin act on
CNS to influence appetite
52
Leptin in normal weight
Suppresses appetite
53
Leptin in obesity
Leptin resistance due to continuous high leptin levels (stops responding)
54
Ghrelin
When empty ghrelin is released, goes to CNS to stimulate appetite Release stopped upon stretch of stomach
55
Glycogenolysis
Breakdown of glucagon to glucose
56
Glucose - short fast
Glycogenolysis Glucose primarily goes to brain and erythrocytes
57
Longer fast- alternative energy sources for gluconeogenesis to produce glucose
Amino acids (from muscles) Lactate (from erythrocytes) Glycerol (from adipocytes)
58
Site of gluconeogenesis
Liver
59
When does ghrelin release stop
Stretch of stomach
60
What hormone controls glycogenolysis
Glucagon
61
Lipolysis
Triglycerides stored in adipocytes Break down triglycerides Produces glycerol and fatty acids
62
Lipolysis- glycerol produced
Transported to liver to produce glucose
63
Lipolysis- produces fatty acids
Transported to kidneys, muscles and liver In liver produce ketones
64
Which tissues can use ketones as an energy source
Muscles CNS
65
Ketogenesis
Ketones released from liver Produced from fatty acids Protein degradation stops to preserve muscle
66
Which tissues can use ketones - prolonged fasting
CNS - during starvation Muscles use less to preserve them for the brain CNS decreases glucose use to preserve glucose for erythrocytes
67
Glucose-6-phosphate —> glycogen
Glycogenesis
68
Glycogen —> glucose-6-phosphate
Glycogenolysis
69
Pyruvate —> glucose-6-phosphate
Gluconeogenesis
70
Acetyl-CoA —>fats and lipids
Lipogenesis
71
Which substances can be measured in blood to give idea about health and disease
Glucose Ketones Insulin Lactate Triglycerides
72
Fats and lipids—> acetyl-CoA
Beta oxidation
73
Post-absorptive phase
CNS and many other tissues preferentially use glucose, produced from glycogen breakdown
74
Gluconeogenic phase
Protein catabolism is used to feed glucose to the CNS, while other tissue feed on ketones and fat
75
Protein conservation phase
Protein catabolism is decreased to a minimum, fatty acids are used everywhere and ketones instead of glucose fuel the CNS
76
Energy balance in
Food and drink
77
Energy balance out
Basal metabolic rate (BMR) Diet induced thermogenesis (DIT)- energy used to break down food Activity- uses the most energy
78
Stable weight
Energy in = energy out
79
Basal metabolic rate (BMR)
Minimum amount of energy to keep body alive
80
How is BMR measured
Using O2 consumption whilst awake, restful and fasted for 12 hours
81
How does age affect BMR
BMR decreases with age
82
Units of BMR
Kcal expended/hr/m^2
83
Factors contributing to obesity
Genetics Environment Energy dysregulation
84
Which enzyme converts glucose to glucose-6-phosphate in liver
Glucokinase
85
Which enzyme converts glucose-6-phosphate to glucose-1-phosphate in liver
Phosphoglucomutase
86
What is glucose-1-phosphate converted to in liver
UDP-glucose
87
Which enzyme adds UDP-glucose to glycogen chain
Glycogen synthase or branching enzyme
88
How much glycogen can be stored in the liver
100g
89
What is glucose-6-phosphate converted to in the liver
Glucose-1-phosphate
90
What is glucose-1-phosphate converted to in the liver
UPD-glucose
91
Lipolysis
Break down triglycerides
92
What are the products of lipolysis
Glycerol and fatty acids
93
Where is glycerol produced by lipolysis transported to
Liver to produce glucose
94
Where are fatty acids produced by lipolysis transported to
Kidneys, muscles and liver In liver produce ketones
95
Which tissues can use ketones as energy
Muscles CNS
96
Ketogenesis
Ketones released from liver CNS uses ketones during starvation Muscles use less ketones to preserve them for brain CNS decreases glucose use Preserves glucose for erythrocytes
97
What do erythrocytes give for gluconeogenesis
Lactate
98
What do muscles give for gluconeogenesis
Amino acids
99
What do adipocytes give for gluconeogenesis
Glycerol
100
Post-absorptive phase
The CNS and many other tissues preferentially use glucose, produced from glycogen breakdown
101
Gluconeogenic phase
Protein catabolism is used to feed glucose to the CNS, while other tissue feed on ketones and far
102
Protein conservation phase
Protein catabolism is decreased to a minimum, fatty acids are used everywhere and ketones instead of glucose fuel the CNS
103
Which glucose transporter is the primary transporter at the gastrointestinal brush border membrane in-between meals
SGLT-1
104
A 24-year-old woman is started on oral iron supplements as she is found to be iron deficient. This is her first time taking iron supplements in her lifetime. The patient has heard about many other medications, foods and drinks that can interfere with the absorption of iron. What substance increases the absorption of the supplement the patient has been prescribed?
Vitamin C (ascorbic acid)
105
Carbohydrates are digested in a series of hydrolysis reactions in the gastro-intestinal tract. Starch/glycogen are hydrolysed by salivary and pancreatic amylase to produce disaccharides, which are further hydrolysed to monosaccharides. The absorption of which monosaccharide does NOT require energy from ATP?
Fructose

GI (12 decks)

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