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Endocrine System > The Endocrine Pancreas COPY > Flashcards

The Endocrine Pancreas COPY Flashcards

1
Q

What parts of the hypothalamus determine the energy balance?

A

Feeding centre

Satiety centre

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2
Q

What controls the feeding and satiety centres?

A

Nutrients in plasma

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3
Q

What is the glucostatic theory

A

Food intake is determined by [BG]

As [BG] increases the drive to eat decreases

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4
Q

What is the lipostatic theory?

A

Food intake determined by fat stores

Leptin release by fat stores depresses feeding centre

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5
Q

What are the 3 elements of metabolism?

A
  1. Extracting nutrients from food
  2. Storing extracted energy
  3. Using the energy to do work
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6
Q

What are the 2 major types of metabolic pathway?

A

Anabolic

Catabolic

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7
Q

Describe anabolic?

A

Build up

Synthesises large molecules from smaller constituents

Stores

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8
Q

Describe catabolic?

A

Breaks down

Breaking down of larger molecules into smaller constituents

Uses stores

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9
Q

What is the absorptive state?

A

Follows after a meal

  • Ingested nutrients are used to supply energy demands
  • Excess energy is stored
  • Anabolic
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10
Q

What is the post absorptive stage?

A

Fasted state between meals and overnight

  • Body demands are reliant on stores
  • Catabolic
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11
Q

What is an obligatory glucose user and name one?

A

Tissue that can only utilise glucose as energy

The brain

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12
Q

What can the brain utilise in extreme starvation?

A

Ketones

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13
Q

What is normal [BG]?

A

4.2 - 6.3mM

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14
Q

How many Islets of Langerhans are there in the average pancreas?

A

1.2 million

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15
Q

What are the 4 types of cells in the islets of langerhans?

A

Alpha

Beta

Delta

F cells

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16
Q

What do alpha cells secrete?

A

Glucagon

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17
Q

What do beta cells secrete?

A

Insulin

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18
Q

What do delta cells secrete?

A

Somatostatin

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19
Q

What do F cells secrete?

A

Pancreatic Polypeptide

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20
Q

What is control of [BG] dependent on?

A

The insulin:glucagon balance

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21
Q

What is the only hormone that lowers [BG]?

22
Q

How is insulin secreted from beta cells?

A
  • Have specific KATP ion channel
  • [BG] ^ causes glucose to enter the cells through a GLUT 2
  • Metabolism increases and the KATP channels are activated
  • K+ enters the cells
  • Cell depolarises
  • Ca2+ channels open and calcium enters
  • Calcium dependent exocytosis of insulin vesicles occurs
23
Q

What is the half life of insulin?

A

About 5 minutes

24
Q

What happens when [BG] is low to beta cells?

A

The cell hyperpolarises so calcium dependent exocytosis can’t occur

25
What is the main role of insulin??
Stimulates glucose uptake by muscles and adipose tissue **(****insulin sensitive tissue)**
26
What is the process of glucose uptake by insulin sensitive tissue?
- Insulin binds to tyrosine kinase receptors on the cell membrane - GLUT 4 transporters mobilised and migrated to the membrane - Allows glucose to enter the cell - When insulin release stops the tyrosine kinase receptor and the insulin molecule are endocytosed and destroyed - GLUT 4 transporters return to cytoplasmic pool
27
What are the other non insulin dependent GLUT transporters?
GLUT 1 - Basal glucose in many tissue (brain, kidney, RBCs) GLUT 2 - beta pancreatic cells and liver GLUT 3 - same as GLUT 1
28
What other pathways are **promoted** by insulin?
Glycogen synthesis Increases amino acid uptake and therefore promotes **protein synthesis** TAG synthesis K+ entry via the sodium potassium pump
29
What processes are inhibited by insulin?
Gluconeogenesis Permissive effect on GH
30
What stimuli increase insulin release?
High [BG] High [AA] Glucagon Incretin hormones Vagal nerve activity
31
What incretin hormones stimulate insulin release?
Gastrin CCK GLP-1 GIP
32
How does vagal nerve activity stimulate insulin release?
- Stimulates release of major GI incretin hormones
33
What stimuli inhibit insulin release?
- Low [BG] - Somatostatin - Sympathetic A2 effects - Stress (e.g. hypoxia)
34
**GLUCAGON QUESTIONS**
35
What type of hormone is glucagon?
Peptide hormone
36
What cells produce glucagon?
Alpha cells of islets
37
What is the primary purpose of glucagon?
Maintain [BG] in the fasted state - Acts on the liver
38
How does glucagon raise [BG] in the fasted state?
Involved in the glucose counter regulatory control system (along with cortisol and GH) - Binds to GPCRs liked to cAMP - Phosphorylates specific liver enzymes resulting in 1. Increase glycogenolysis 2. Increased gluconeogenesis 3. Formation of ketones from FA's
39
When is glucagon secreted?
Relatively constantly - Increases when [BG] \< 5.6mM - Ratio of glucagon:insulin most significant
40
What other processes stimulate the release of glucagon?
- High [AA] - Low [BG] - Sympathetic B2 innervation - Cortisol - Stress
41
What inhibits glucagon release?
- High [BG] - FFAs - Ketones - Insulin - Somatostatin
42
How do amino acids regulate [BG] after a meal?
Release both insulin and glucagon to ensure that hypoglycaemia doesn't occur - Also ensures that obligatory glucose utilisers get enough glucose
43
What is the parasympathetic effect on islets?
- Vagus - Increases insulin release - Increases glucagon release (to a lesser effect)
44
During what phase does the vagus act?
Cephalic phase
45
What is the effect of the sympathetic phase on islets?
- Promotes glucose release - Increases glucagon - Increases epinephrine
46
47
What type of hormone is somatostatin?
Peptide hormone
48
What cells secrete somatostatin?
D cells Hypothalamus
49
What are the functions of somatostatin?
- Slow down GI tract (i.e. reduce absorption of nutrients to prevent plasma spikes) - Strongly suppresses the release of both insulin and glucagon
50
What stimuli promote somatostatin release?
- [BG] high - [AA] high
51
What effect does insulin have during exercise?
- Glucose enters muscle more in exercise even without insulin - Insulin sensitivity is increased so GLUT 4 mediated transport increases - This allows the muscle to get better energy supply
52
What happens to adipose tissue during starvation?
- Broken down into FFAs - These can be readily used by most tissue but brain requires Glc/Ketones - Brain adapts - This spares protein so muscle wasting doesn't occur - Protein is used after fat stores are depleted

Endocrine System (90 decks)

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