Module 5 : Structure and function of the pancreas Flashcards

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1
Q

Is the pancreas an example of an exocrine or an endocrine gland?

A

it has roles as both an exocrine or an endocrine gland

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2
Q

What is the function of the pancreas as an exocrine gland?

What is the function of the pancreas as an endocrine gland?

A

to produce enzymes and release them via a duct

to produce hormones and release them into the blood

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3
Q

Name the three important enzymes produced by the pancreas and state the role of each

A

amylases-break down starch into simple sugars

proteases-break down proteins into amino acids

lipases-break down lipids into fatty acids and glycerol

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4
Q

Name the 2 hormones produced by the pancreas

What are these hormones essential for?

A

insulin and glucagon

controlling blood glucose concentration

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5
Q

Where within the exocrine tissue of the pancreas are insulin and glucagon produced

Where are these hormones secreted to?

A

in the islets of Langerhans

directly into the bloodstream

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6
Q

Name the 2 different types of cells within the islets of Langerhans , then name which hormone they produce/secrete?

A

alpha cells-produce and secrete glucagon

beta cells-produce and secrete insulin

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7
Q

Blood glucose concentration can be increased through … 3

describe each

A

diet-through eating carb rich foods , these are broken down in the digestive system to release glucose

glycogenolysis-glycogen stored in the liver is broken down into glucose which is released into the bloodstream

gluconeogenesis-production of glucose from non carb sources , involves amino acids and glycerol

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8
Q

Blood glucose concentration can be decreased by … 2

A

respiration-some glucose is used by cells to release energy for normal bodily functions ,when exercising more glucose is needed to supply the body with energy to allow muscles to contract

glycogenesis-when concentration is too high , excess glucose is taken in and converted into glycogen in the liver

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9
Q

Describe the role of insulin in regulating blood glucose concentration

make 3 points

A
  • beta cells detect a rise in blood glucose concentration and secrete insulin directly into blood stream

insulin binds to glycoprotein receptors on body cells , it changes the tertiary structure of glucose transport protein channels

this causes channels to open allowing more glucose to enter the cells

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10
Q

Give the 5 ways insulin decreases blood glucose concentration in the body…

A

1)increases rate of absorption of glucose by cells
2)increases respiratory rate of cells
3)by stimulating the liver to increase the rate of glycogenesis so glycogen can be stored in liver and muscle cells
4)increasing the rate of glucose to fat conversion
5)inhibiting release of glucagon from alpha cells in islets of Langerhans

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11
Q

Why must insulin constantly be secreted?

As blood glucose returns to its normal level , what cells detect this?

A

because its broken down by enzymes in the cells of the liver

beta cells of the pancreas

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12
Q

When beta cells detect glucose concentration has gone below a certain level , what happens?

What type of feedback is this?

A

they reduce their insulin secretion

this is an example of negative feedback

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13
Q

Glucagon is produced by what cells found in the islet of Langerhans?

Only 2 types of body cells can respond to glucagon , name these

A

alpha cells

liver and fat cells

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14
Q

Give the 3 ways that glucagon can raise blood glucose concentration

A

1)glycogenolysis-the liver breaks down its glycogen store into glucose and releases it back into the bloodstream
2)reducing the amount of glucose absorbed by liver cells
3)increasing gluconeogenesis-increasing conversion of amino acids and glycerol into glucose in the liver

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15
Q

Describe steps 1 , 2 and 3 of the mechanism in which beta cells release insulin

A

1)at normal blood glucose concentration , potassium ion channels in plasma membrane are open and ions diffuse out the cell( resting potential in -70mV
2)when concentration rises , glucose enters the cell by a glucose transporter
3)the glucose is metabolised inside the mitochondria resulting in the production of ATP

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16
Q

Describe steps 4 and 4 of the insulin secretion mechanism of beta cells

A

4)ATP binds to potassium channels and causes them to close
5)as potassium ions can no longer diffuse out the cell , the potential difference of the cell reduces to -30mV and depolarisation occurs

17
Q

What is the name given to the potassium ion channels on beta cells?

A

ATP sensitive potassium ion channels

18
Q

Describe steps 6 and 7 of the insulin secretion mechanism

A

6)depolarisation causes voltage gated calcium ion channels to open
7)calcium ions enter the cell and cause secretory vesicles to release insulin by exocytosis