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47 Cards in this Set
- Front
- Back
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What kind of organ is the pancreas?
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Can be an Endocrine organ
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Where is the pancreas located?
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Behind the stomach
Has endocrine and exocrine function |
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Is the pancreas mostly an endocrine organ?
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No
99% of the pancreas is exocrin and secretes digetive enzymes |
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What are the endocrine structures of the pancreas?
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Islets of Langerhans: compact mass of cells with good vascularization (readily enters the circulation)
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What type of cells (and %) make up the langerhan islets cells and what do they produce?
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-60% beta cells: make insulin
-25% alpha cells: make glucagon -other cells, like delta cells, make somatostatin and other H |
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What areinsulin and glucagona and what do they do?
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Small protein H
Control [glucose] in the blood |
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What is more important: insulin or glucagon? Why?
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Insulin
Insulin deficiency or absence significantly compromises the well being of someone and can lead to death |
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What does insulin do?
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Primarily decreases blood glucose (only H to do this)
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Where is there always glucose?
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The blood
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What is the fasting level of glucose?
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5mM (80mg/100ml)
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Does glucose rapidly diffuse through the body's cells?
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No, except for the brain
.: Glucose must be transported |
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What is glucose converted to in the:
-muscles and liver? -adipose tissue? -body cells? |
Liver and muscles: glycogen
Adipose tissue: fat Body cells: oxidized to produce E |
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What kind of recpetor is the insulin receptor?
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Membrane receptor (not open receptor)
Stimulaes insertion of glucose transport proteins stored in the cytoplasm into the PM Increases glucose uptake |
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What happens when the beta cells are destroyed?
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Insulin deficiency
Diabetes mellitus -> most tissues cannot take up glucose efficiently, glucose accumulates in circulation ->occurs even if no glucose in diet because increased gluconeogenesis -> free fatty acids becomes the main source of E ->get inceased lipolysis ->Fat is inefficiently used: incomplete oxd of FFA ->Increased circulation acetoaceti acid and B-hydroxybutyric acid (metabolic acidosis) and acetone (ketosis) -> decreased blood pH: diabetic coma |
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What are symptoms of diabetes mellitus?
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Increase of blood glucose
At >180mg% glucose spills over into urine--> glycosurea ->loss of water in urine, get polyurea |
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What is polyurea?
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Dehydration and increased thirst (polydipsia)
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What can happen if diabetes mellius is untreated?
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-Ketosis: acetone smell in breath
-Metabolic acidosis |
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How can diabetes mellitus be treated?
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Insulin injections
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What must be done for those in diabetic comas?
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Acidosis and ass't electrolyte imbalance has to be corrected, in addition to insulin administration
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What is diabetes insipidis? How can it be distinguished from diabetes mellitus?
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Antidiuretic hormone deficiency
Mellitus has sweet urine |
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What is type 1 and type 2 diabetes?
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Type 1: Insulin dependent diabetes mellitus, insulin deficiency
Type 2: insulin independent diabetes mellitus, hyporesponsiveness to insulin |
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What can be the cause of type 1 diabetes? Treatment?
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1) Destruction of beta cells of pancreas: don't make insulin
Treatment: administer insulin 2) Defective insulin release Treatment: drugs to stimulate insulin release |
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What happens if too much insulin is administered?
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Insulin shock/hypoglycemic coma
->happens when blood glucose= 20-30mg/100mL and availability of glucose for the brain is insufficient |
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What happens in type 2 diabetes?
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Insulin levels are normal or too high
Hyporesponsiveness of target cells to insulin (insulin resistance) Can be due to decreased number of insulin receptors Associated with obesity from overeating (downregulation of receptors because of prolonged high level of insulin) |
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How can type 2 diabetes be treated?
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proper diet and exercise
decreased caloric intake, dec insulin production, upregulation of receptors Insulin receptors increased in response to frequent endurance exercise (independent to changes in body weight) |
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What is juvenile diabetes mellitus?
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Appears in childhood
Type I (insulin dependent) Beta-cells of the pancreas don't produce insulin Treatment requires administration of insulin |
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What is the glucose tolerance test?
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Overnight fast of 12 hrs
Patient given 0.75-1.5g of glucoses/kg body weight -Blood taken before admin and at 30-60 min intervals after -blood glucose in a normal indivifual increases i the 1st hour then returns to normal 2-3 hrs after In a diabetic: blood glucose increase is greater than normal and returns to normal more slowly |
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How is glucose tolerance in ppl with diabetes? With hyperinsulinism?
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Diabetes: Glucose tolerance decreases
Hyperinsulinism: Glucose tolerance increases |
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What is required to avoid hypoglycemia?
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Efficient fdbk control of insulin release
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What are control mechanisms of insulin secretion?
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- Beta cells respond to levels of blood glucose, secreting little or no insulin when blood glucose is low, secreting much more when the blood glucose is high
-Release of gastrin and vagal impulses to the beta cells induce insnulin release ->insulin starts to leave the pancreas even before the bloood glucose begins to rise during meals |
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What is glucagon?
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Peptide hormone
Synthesized and released by alpha cells of pancreas |
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What are the metabolic functions of glucagon?
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Like epinephrine
Raise blood sugar by promoting glycogenolysis and gluconeogenesis in the liver Increases the rate of lypolysis in adipose tissu -> increased [FFA] in circulation |
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What does glucagona interact with? What does it stimulate?
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Interacts with mb receptor
Stimulates activity of adenylyl cyclase Increases production of cAMP (GPCR) |
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What controls the release of glucagon?
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[glucose] in circulation
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What happens if there is low blood glucose?
High blood glucose? |
Low: Stimulate alpha cells to increase the synthesis and release of glucagon
High: Decrease release and synthesis of glucagon |
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What are some other H that increase blood glucose levels?
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Cortiso (glucocortcoids)
Nor/epinephrine |
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What is growth hormone (GH)?
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Responsible for growth
(Somatotropin: STH) Single chain polypeptide: has great specificity (only human GH promotes growth in humans) |
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Where is GH produced?
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Anterior lobe of pituitary
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What does GH do?
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-Increases protein synthesis in many tissues (bone, muscle, kidney, liver) enhancing aa uptkae by cells and by accelerating the transcription/translation of mRNA
-Increases rate of lypolysis and utilization of FFA as a source of E (this is a direct effect of GH not mediated by somatomedins) |
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What are somatomedins?
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Substances produced by the liver under the stimulation f GH
-structurally similar to insulin -named insulin-like GH I/II (IGFI/II) |
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What do somatomedins bind?
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Insulin receptors
Insulin at high concentration may bind somatomedin receptors |
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What do somatomedins do?
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Increase protein synthesis
Stimulate growth |
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What controls GH release?
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2 hypothalamic neurohormones (complex fdbk mechanism)
1) GH releasing hormone (GRH or somatoliberin) stimulates GH release 2) Somatostatin (GH inhibitin hormone) inhibits GH release |
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What regulates GRH and somatostatin?
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Integrated system of neural metabolic and hormonal factors
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What inhibits somatostatins? Activates them?
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Inhibit: Exercise, sleep
Activate: stress, low blood sugar |
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What happens in GH deficiency?
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In the young: decreased physical growth
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What happens if excess GH?
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Young: Gigantism
Adult: Acromegaly-> many bones, especially in the cartilaginous regions, get longer and heavier Face can change, jaw size increases, eyebrows get bigger |
