Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Z OLD ESA 1- Metabolism > The Endocrine Pancreas > Flashcards

The Endocrine Pancreas Flashcards

1
Q

What is the pancreas?

A

A large gland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where is the head of the pancreas?

A

Nestled in the curvature of duodenum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How does the pancreas develop embryologically?

A

As an outgrowth of the foregut

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the functions of the pancreas?

A
  • Produces digestive enzymes secreted directly into duodenum
  • Hormone production
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What forms the bulk of the pancreas?

A

Exocrine function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Of what nature are the pancreas’ exocrine secretions?

A

Alkaline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where do the pancreas’ exocrine secretions go?

A

Into the duodenum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How do the pancreas’ exocrine secretions get into the duodenum?

A

Through the pancreatic duct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where does the pancreas produce hormones?

A

From Islets of Langerhans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How much of the pancreas is endocrine function?

A

~1%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How to the areas responsible for endocrine secretion appear on a micrograph of the pancreas?

A

As paler pink regions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What kind of hormones does the pancreas secrete?

A

Polypeptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What hormones does the pancreas secrete?

A
  • Insulin
  • Glucagon
  • Somatostatin
  • Pancreatic polypeptide (PP)
  • Ghrelin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What cells secrete insulin?

A

ß-cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What cells secrete glucagon?

A

α-cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What cells secrete somatostatin?

A

Delta cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What cells secrete PP?

A

F cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are insulin and glucagon used in the regulation of?

A

Metabolism of carbohydrates, proteins and fats

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is somatostatin used in?

A

Islet cell secretion regulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is PP used in?

A

GI function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does insulin do to blood glucose?

A

Lowers it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What detects high blood glucose?

A

The pancreas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What happens when the pancreas releases insulin?

A

Fat cells taken in glucose from the blood, achieving normal blood glucose levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What effect does glucagon have on blood glucose?

A

Raises it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How does glucagon raise blood glucose?

A

Causes liver to release glucose into the blood, achieving normal blood glucose levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is insulin signalled by?

A

Feeding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the target tissues for insulin?

A
  • Liver
  • Adipose
  • Skeletal muscle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What kind of action does insulin cause?

A

Anabolic- building

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is glucagon signalled by?

A

Fasting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are the target tissues for glucagon?

A

NAME?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What kind of actions does glucagon have?

A

Catabolic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What uses glucose at the fastest rate in the body?

A

Brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What does the brain rely on for its glucose?

A

Blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the brain sensitive to?

A

Rises or falls in plasma glucose level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What does a rise in plasma glucose level cause that the brain is sensitive to?

A

Increased osmolarity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Why does the circulation of glucose in the blood need to be controlled?

A

The brain doesn’t have it’s own supply of glucose, and so relies on the circulatory system to supply and steady and regular amount

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What are the normal plasma glucose concentrations?

A
  • Normally 3.3-6mmol/L

- After a meal 7-8mmol/L

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the plasma glucose renal threshold?

A

10mmol/L

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is glucosuria?

A

When glucose is excreted in urine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

When is the renal threshold decreased?

A

In pregnancy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

When is the renal threshold increased?

A

In the elderly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Are insulin and glucagon water or lipid soluble?

A

Water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

How are insulin and glucagon carried?

A

Dissolved in the plasma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Do insulin and glucagon require special transport proteins?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

How long is the half life of insulin and glucagon?

A

5 mins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What happens to insulin and glucagon at target cells?

A

They interact with cell surface receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

How can a receptor with a hormone bound be inactivated?

A

It can be internalised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What is insulin important in the storage of?

A
  • Carbohydrates
  • Protein
  • Fat
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What does insulin act against?

A
  • Gluconeogenesis
  • Lipolysis
  • Ketone formation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Is insulin glycogenic?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What does insulin consist of?

A

Two unbranched polypeptide chains, connected by 2 disulphide bridges

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What do the disulphide bridges in insulin ensure?

A

Stability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

How many amino acids are there in insulin?

A

51; 21 α, 30 ß

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What does insulin start as?

A

Preproinsulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Why does insulin start as preproinsulin?

A

Because insulin mRNA is translated as a single chain precursor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

How is proinsulin generated?

A

Removal of it’s signal peptide during insertion into the ER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What happens to proinsulin within the Golgi?

A

It is exposed to several specific endopeptidases, which excise the C peptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What does the excision of the C peptide from insulin generate?

A

Mature form of insulin, and a C peptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What happens to the newly generated insulin and C peptide?

A

It’s packaged in the Golgi into secretory granules, which accumulate in the cytoplasm. They are now packaged ready for exocytosis

60
Q

What is margination?

A

When granules move to the cell surface

61
Q

What is the purpose of margination?

A

The granules are held in preparation within pancreatic ß-cells ready for need of secretion

62
Q

What happens in exocytosis?

A

Fusion of vesicle membrane with plasma membrane to release the vesicle contents

63
Q

How much of the insulin stored in the pancreas is secreted in a day?

A

15%

64
Q

Why is the half life of insulin only 5 minutes?

A

Because there is no carrier

65
Q

What is the stimulus for insulin release?

A

Increase in glucose in the extracellular fluid

66
Q

How is glucose transported into the ß-cell?

A

Facilitated diffusion through GLUT2

67
Q

What does an increase in [glucose ecf ] mean?

A

Increased concentrations of glucose within the ß-cell

68
Q

What happens to glucose once it’s inside the pancreatic ß-cell?

A

It is phosphorylated by glucokinase

69
Q

What happens once glucose has been phosphorylated?

A

It goes through glycolysis respiration

70
Q

What is the result of the phosphorylated glucose going through glycolysis respiration?

A

Increase in ATP:ADP ratio

71
Q

What does the increase in ATP:ADP ratio in the pancreatic ß-cell lead to?

A

Depolarisation the membrane

72
Q

Why does an increase in ATP:ADP ratio lead to depolarisation of the membrane?

A

As ATP-sensitive potassium channel (K ATP channels) open, allowing influx of K +

73
Q

What does the K + influx lead to?

A

Influx of extracellular calcium

74
Q

Why does K + influx lead to an influx of extracellular calcium?

A

Voltage-gated calcium channels open

75
Q

What does an increase in ECF calcium in the ß-cell trigger?

A

Exocytosis of insulin-containg secretory granules

76
Q

What are the metabolic insulin effects?

A
  • Increases glucose uptake in target cells and glycogen synthesis
  • Inhibits breakdown of fatty acids
77
Q

How does insulin increase glucose uptake?

A

Insertion of GLUT4 channel

78
Q

What is the effect of insulin in the liver?

A
  • Increases glycogen synthesis by stimulating glycogen formation and by inhibiting breakdown
  • Inhibits breakdown of amino acids
79
Q

What is the effect of insulin in muscles?

A

It increases uptake of amino acids, promoting protein synthesis

80
Q

What is the effect of insulin in adipose tissue?

A

Increases storage of triglycerides

81
Q

Where does insulin bind?

A

To the insulin receptor on the cell surface

82
Q

What kind of molecule is the insulin receptor?

A

A dimer

83
Q

What is the structure of the insulin receptor?

A

Two identical sub-units spanning the cell membrane

84
Q

What are the insulin receptor sub units made up of?

A

1 α chain and one ß chain, connected by a single disulphide bond

85
Q

Where is the α chain of the insulin receptor?

A

On the exterior of the cell membrane

86
Q

Where is the ß chain of the insulin receptor?

A

Spans the cell membrane in a single segment

87
Q

How is the insulin receptor activated?

A
  • α chains move together when insulin is detected, and fold around the insulin
  • Moves the ß chains together
  • This makes the ß chains an active tyrosine kinase
  • Initiates a phosphorylation cascade, resulting in increase in GLUT4 expression
88
Q

What does the increase in GLUT4 expression mean?

A

Means cell can take up more glucose

89
Q

What does glucagon do?

A

Acts to raise blood glucose

90
Q

How does glucagon act to raise blood glucose?

A
  • Glycogenolytic
  • Gluconeogenesis
  • Lipolytic
  • Ketogenic
91
Q

What does glucagon mobalise?

A

Energy release

92
Q

What secretes glucagon?

A

α cells

93
Q

What is glucagon secreted in response to?

A

Low glucagon levels in α cells

94
Q

Where is glucagon synthesised?

A

Rough ER

95
Q

What happens to glucagon once it has been synthesised?

A

It’s transported to Golgi

96
Q

How is glucagon packaged?

A

In granules

97
Q

Where does glucagon have its main effect?

A

In the liver

98
Q

What happens following margination of glucagon granules?

A

They are held at the cell surface until stimulus of low blood glucose is detected by pancreatic α cells

99
Q

What happens once the pancreatic α cells have detected the stimulus of low blood glucose?

A

The vesicle membrane fuses with the plasma membrane with the release of the vesicle contents, in a process called exocytosis

100
Q

How many amino acids does glucagon have?

A

29

101
Q

How many polypeptide chains does glucagon have?

A

1

102
Q

Does glucagon have disulphide bonds?

A

No

103
Q

What is the result of glucagon having no disulphide bonds?

A

It’s flexible

104
Q

How does the synthesis of glucagon differ from that of insulin?

A

It’s simpler

105
Q

What are the effects of glucagon?

A
  • In the liver, it increases the rate of glycogen breakdown
  • Stimulates gluconeogenesis pathways
  • Stimulates lipolysis
106
Q

What is the result of glucagon stimulating lipolysis?

A

Increases plasma fatty acids

107
Q

What is the net effect of glucagon?

A

Rise in blood glucose levels

108
Q

What effect does an increase in amino acids have?

A

Increase in insulin and glucagon

109
Q

What effect does an increase in fatty acids have?

A

Increases insulin

110
Q

What is the effect of an increase in GI tract hormones?

A

Increase in insulin

111
Q

What is the effect of an increase in adrenaline and noradrenaline?

A

Decrease in insulin, increase in glucagon

112
Q

How quickly does insulin and glucagon affect glucose uptake in muscle and adipose tissue?

A

Rapidly

113
Q

How quickly do hormones affect gluconeogenesis and glycogenesis?

A

Intermediate- in minutes

114
Q

What effect do insulin and glucagon have on lipogenesis?

A

NAME?

115
Q

What effect do insulin and glucagon have on ketogenesis?

A

NAME?

116
Q

How quickly do hormones affect lipogenesis?

A

Delayed- takes hours

117
Q

What effect does insulin and glucagon have on amino acid uptake?

A

NAME?

118
Q

How quickly do hormones affect amino acid uptake?

A

Rapidly- seconds

119
Q

What effect does insulin and glucagon have on protein synthesis?

A
  • Increased by insulin

- Decreased by glucagon

120
Q

How quickly do hormones affect rates of protein synthesis?

A

Intermediate- minutes

121
Q

What happens if insulin is excessively high?

A

Hypoglycaemia

122
Q

What happens if insulin is deficient?

A

Hyperglycaemia

123
Q

What happens if glucagon is excessively high?

A

Makes diabetes worse

124
Q

What happens if glucagon is deficient?

A

May contribute to hypoglycaemia

125
Q

What is type 1 diabetes caused by?

A

An absolute insulin deficiency caused by autoimmune destruction of pancreatic ß-cells

126
Q

What is a relative insulin deficiency?

A

When the secretory response of ß-cells abnormally slow/small

127
Q

What are the potential aetiologies of type 2 diabetes?

A

NAME?

128
Q

How could the insulin receptor mechanism be defective?

A

Change in receptor number and/or affinity

129
Q

What is meant by defective post-receptor events?

A

Insulin resistance

130
Q

What happens in insulin resistance?

A

The tissues become de-sensitive to insulin

131
Q

What is diabetes insipidus?

A

An uncommon condition that occurs when the kidneys are unable to conserve water as they perform their function of filtering blood

132
Q

What are the main sites of glucose utilisation?

A

NAME?

133
Q

What do the main sites of glucose utilisation show in insulin resistance?

A

Decreased response to normal circulating concentrations of insulin

134
Q

What % of the population does insulin resistance affect?

A
  • ~25% of general population

- ~92% of patients with type 2 diabetes

135
Q

What does insulin result from?

A

NAME?

136
Q

What environmental factors can cause diabetes?

A
  • Obesity

- Sedentary lifestyle

137
Q

Relative to hyperglycaemia and development of type 2 diabetes, when is insulin resistance present?

A

12+ years before

138
Q

How does insulin resistance develop?

A
  • Initially, ß-cells compensate by increasing insulin production, maintaining normal blood glucose
  • Eventually, ß-cells are unable to maintain increased insulin production, leading to impaired glucose tolerance
  • Finally, ß-cell dysfunction leads to relative insulin deficiency, using overt type 2 diabetes
139
Q

Why does insulin deficiency/resistance cause chronic hyperglycaemia?

A
  • In the muscles, insulin decreases the uptake of glucose and glycogenesis
  • In the adipose tissue, insulin decreases uptake of glucose and decreases lipogenesis and esterification
  • In the liver, insulin decreases glycogenesis and glycolysis, and increases gluconeogenesis
    If there is no insulin, these things do not happen, causing hyperglycaemia
140
Q

What are the long term complications of hyperglycaemia in the muscle?

A

The decreased uptake of amino acids and protein synthesis causes an increase in proteolysis, causing muscle wastage

141
Q

What are the long term complications of hyperglycaemia in the adipose?

A

Decreased esterification leads to increased lipolysis, leading to weight loss

142
Q

What are the long term complications of hyperglycaemia in the liver?

A

Gluconeogenesis from muscle amino acids, leading to muscle wastage.
Ketogenesis from adipose tissue fatty acids, leading to ketosis

143
Q

What are the acute metabolic consequences of hyperglycaemia?

A
  • Glucosuria
  • Polyuria
  • Polydipsia
144
Q

What are the chronic consequences of diabetes?

A

NAME?

145
Q

What are the microvascular diseases caused by chronic hyperglycaemia?

A
  • Eye disease, including retinopathy
  • Nephropathy in kidneys)
  • Neuropathy in peripheral nervous system
146
Q

What macrovascular disease is caused by chronic hyperglycaemia?

A
  • Coronary artery disease
  • Stroke
  • Poor peripheral circulation

Z OLD ESA 1- Metabolism (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions