GHM L7 Flashcards
Describe the location of the pancreas
Abdominal, behind stomach
15 cm long
Describe the anatomy of the pancreas
3 parts:
Head (points into the inner curvature of the duodenum)
Body (longest part, the main pancreatic duct and the accessory pancreatic duct run through the body)
Tail - adjascent to spleen
Pancreas opens into the duodenum
Has lobules
How does the hepatopancreatic ampulla form?
When common bile duct joins with main pancreatic duct
State the secretory cells in the pancreas
- Duct cells
- Acinar cells
What is the function of acinar cells ?
- Secrete digestive enzymes
What is the function of duct cells?
Secrete bicarbonates
What does pancreatic juice consist of?
Digestive enzymes (proteases, lipases, nucleases, amylases) and bicarbonates (HCO3-)
State which hormones control the formation of pancreatic juice
CCK - stimulates acinar cells to release digestive enzymes
Secretins - stimulate duct cells to release bicarbonates
State what stimulates the release of CCK?
TG, FA, AA
State what stimulates the release of secretin?
acidic chyme
What are the 3 types of cells present in the islet of langerhan in the pancreas consist of?
- Alpha cells - (glucagon producing)
- Beta cells - (insulin producing)
- Acinar cells - (exocrine)
State the function of bicarobonates in pancreatic juice
Neutralise acidic chyme
Balance the acid from the stomach
Pancreatic proteases
Pancreatic proteases are released as zymogens
Zymogens are then activated in the small intestine
For example, trysinogen is activated into trypsin by enteropeptidase
Amylases, nucleases, lipases
Do not need to be activated, they are secreted inrto duodenum in active form
They just need
Ions / bile
State the endocrine function of the pancreas
Occurs in islet of langerhans
- Alpha cells - secrete glucagon
-Beta cells - secrete insulin
-Delta cells - somatostatin - PP cells - secrete pancreatic polypeptide - regulation of gastric secretions
State the exocrine function of the pancreas
Release of fluid (pancreatic juice) via pancreatic ducts onto epithelial surface of duodenum
Digestive enzymes
-Proteases
-Lipases
-Nuclueases
-Carboxypeptidases
Bicarbonates (HCO3-)
What is the function of insulin?
Blood glucose homeostasis (reducing blood glucose levels)
How is insulin secreted ?
Beta cells, islets of langerhans, to TARGET ORGANS
- Muscle / skeletal tissue
-Liver
-Adipose tissue
How does insulin act on its target organs?
Muscle Tissue:
Increases gluocse uptake from blood - converts glucose to glygen - glycogenesis
Increase amino acid uptake from blood - to form protein (protein synthesis)
Decreased glycogen + protein breakdown
Liver
Increased glucose uptake from blood to produce glycogen - glycogenesis
Decreased rate of glycogenolysis - glycogen to glucose
Increased TAG synthesis
Decreased ketone formation
Decreased protein + TAG breakdown
Adipose tissue
Increased uptake of glucose from blood, leading to fat production (increased TAG synthesis, decreased TAG breakdown)
State the function of glucagon
Blood glucose homeostasis - increases glucose conc
How is glucagon secreted?
Alpha cells in islets of Langerhans
To target hormone - Liver
How does glucagon act on its target hormone?
Liver:
Increases glycogenolysis (glycogen - glucose), increase conc of enzyme glycogen phosphorylase
Increases fatty acid uptake and glycerol uptake to form glucose
Decreases glycognesis - therefore, decreases conc of enzyme glycogen synthethase
Why is blood glucose level controlled in a counter regulatory manner?
Because the actions of insulin and glucagon oppose each other
Explain the counter-regulatory control of blood glucose homeostasis
Glucagon release is inhibited when insulin is released / presence of insulin
Glucagon is released when no insulin
-Starvation
-Exercise
-Stress
Why is glucagon released during times of starvation exercise/starvation/stress?
In these times, low blood glucose levels
Glucagon is secreted by alpha cells in the islets of Langerhans to its target organ - liver
It mobilises glucose stores (glycogen) and provides glucose to muscles during exercise
Describe how insulin is controlled by a negative feedback mechanism
Insulin is controlled by a negative feedback mechanism in response to low levels of glucose upon insulin secretion
Diagram L7
Describe how glucagon is controlled by negative feedback
Glucagon is controlled by negative feedbackl in response to high glucose levels upon glucagon secretion
Diagram L7
Explain the role of the nervous system of blood glucose levels
Parasympathetic nervous system innervates the islets of Langerhans
-neurotransmitter - ACh
-Stimulates insulin secretion
Sympathetic nervous system innervates islets of Langerhans
-Neurotransmitter - Noradrenaline
-Stimulates glucagon release
-Inhibits insulin release
State two other hormones involved in glucose regulation
Glucocorticoids
Somatostatins
State the function of glucocorticoids
Cortisol - secreted by adrenal cortex
Function:
Increases gluconeogensis
Decreases glucose utilziation by cells
Increases release of fatty acids by adipose cells
State the function of somatostatins
Decreases insulin and glucagon secretion
What is diabetes mellitus?
- Decreased sensitivity of cells to insulin
- Insulin deficiency
- Complete lack of insulin
What is the cause of Type 1 diabetes?
IDDM - insulin dependent diabetes mellitus
State the cause of gestational diabetes
What other complications can it lead to?
Pregnant women, No prior diabetes
Natural - interference with insulin receptors
Persistant hypergylcemia - increased risk of big baby syndrome macrosomia - miscarriage
Recovery usually follows delivery
Why must insulin be administered
by injection and not orally?
Insulin is a peptide hormone and therefore, can be destroyed by gastric acid in the stomach
Why may insulin treatment itself be
hazardous?
Hypoglycemoa
State pathologies related to the pancreas
- Pancreatic cancer
- Acute / chronic pancreatitis
- Cystic fibrosis
- Exocrine pancreatic insufficiency
State a common cause of acute pancreatitis
Gall stones (and high triglyceride levels)
State a common cause of chronic pancreatitis
Alcohol (and high triglyceride levels)
State the two types of pancreatic cancers
Exocrine cancer
Neuroendocrine cancer
State a cause of pancreatic exocrine cancer
Acinar cell carcinoma
Leads to increase in production of digestive enzymes
State a cause of pancreatic neuroendocrine cancer
Pancreatic neuroendocrine tumours (PaNETP) - benign / malignant
Can be functioning / non-functioning
Functioning - produce hormones: insulin (insulinomas), gastrone (gastrinomas),
Why can pancreatic neuroendocrine cancer be dangerous?
Often has late diagnosis
