LEC 26: Pancreas2 Flashcards
LEC 26: Pancreas
What organ produces glucose?
The liver
LEC 26: Pancreas
Which organ is important for normal glucose homeostasis?
The pancreas
LEC 26: Pancreas
What are the endocrine producing cells of the pancreas?
Islet cells of Langerhans
LEC 26: Pancreas
What part of the pancreas makes glucagon?
Alpha cells
LEC 26: Pancreas
What part of the beta cells of the pancreas make?
Insulin
LEC 26: Pancreas
What part of the alpha cells of the pancreas make?
Glucagon
LEC 26: Pancreas
What does Ghrelin do?
“Feed me” peptide, mainly secreted by the stomach and increases hunger
LEC 26: Pancreas
What stimulates the beta cells?
Glucose
LEC 26: Pancreas
What inhibits glucagon production and promotes insulin production?
GLP-1, from the gut, related to meals
LEC 26: Pancreas
What is proinsulin?
From the pancreas, is cleaved to form insulin.
LEC 26: Pancreas
What is the importance of measuring C-Peptide?
Used as an indicator of insulin production and pancreas function, more stable and hangs around for hours
LEC 26: Pancreas
Glucose transporter (GLUT 2)
Has a low affinity to bring glucose into the pancreatic beta cells. The glucose then goes to the mito to get metabolized and that ATP closes the K channel making positive charges to build up inside the cell. That then causes the VDCa (voltage dependent calcium) channel to open and brings Ca into the cell. The Ca then promotes the secretion of insulin out of the cell
LEC 26: Pancreas
What impact does glucose have on the cell?
Gets metabolized in the mito and creates ATP that closes the K channel and depolarizes the cell membrane.
LEC 26: Pancreas
What impact does Ca have on the cell in terms of insulin production?
Ca promotes the secretion of insulin out of the cell via transport vesicles.
LEC 26: Pancreas
Insulin receptor
Tyrosine kinase, it is complete w/ 2 alpha subunits that are connected by disulfide bond. each alpha subunit is connected to a beta subunit by a disulfide bond.
The role of Insulin
Promotes cell growth, proliferation, gene expression (MAP kinase signaling pathway)
PI-3K Pathway: synthesis of lipids, proteins, glycogen. Cell survival
GLUT4 - makes cells insulin responsive and facilitates the absorption of glucose into cells
How the brain gets glucose
Glut 3 (insulin independent intake), GLUT1 (partially dependent) GLUT4 (dependent)
GLUT2 transporter
Low affinity, concentration dependent (glucose can move out of the liver during gluconeogensis)
GLUT4 transporter
Insulin dependent uptake found primarily in fat and muscle
Glucagon
is the major counter to insulin action.
Response to low glucose:
Glucagon and epinepherine production - operate to mobilize the glycogen in the liver and turn it into glucose
Substrate mobilization: Cortisol and Growth Hormone, deliver substrate to break down fat and muscle to make glucose in the liver
Response to high glucose:
Pancreas secretes insulin through the stimulation of GLUT2. Insulin then turns on GLUT4 and glucose is absorbed from the blood. Goes to the liver and tells it to store glucose as glycogen.
GLP-1
Gets secreted when we eat from the GI track. Augments and increases insulin secretion in the pancreas. Lowers glucagon secretion. Beta cells proliferates. Lowers the appetite and delays gastric emptying.
Response to low glucose:
Alpha cells in the pancreas releases glucagon into the blood which tells the liver to start breaking down glycogen and releases glucose into the blood.
