Blood Glucose Regulation ✅ Flashcards
What organ plays a major role in the regulation of blood glucose concentrations?
The pancreas
What is the embryological origin of the pancreas?
Endodermal, arising from the embryonic foregut
What happens to the pancreatic bud endoderm in embryological development?
Islet cell clusters differentiate from the pancreatic bud endoderm. These cell clusters from acini and ducts. On the edge of these cell clusters, pancreatic islets form
What are Pax genes?
A family of genes coding for tissue specific transcription factors
What Pax genes are involved in pancreatic embryological development?
Pax-6 and Pax-0
What does Pax-6 do?
Facilitates development of pancreatic β and δ cells
What do pancreatic β-cells release?
Insulin
What do pancreatic δ-cells release?
Somatostatin
What does Pax-0 do?
Facilitates development of α and γ cells
What do pancreatic α cells release?
Glucagono
What do pancreatic γ cells release?
Pancreatic polypeptide
When is fetal endocrine function evident?
10-15 weeks
What cells regulate pancreatic endocrine function?
Islets of Langerhans
Describe the structure of the Islets of Langerhans?
Insulin secreting beta cells occupy the central part, and are surrounded by a ring of glucagon secreting alpha, and somatostatin secreting delta cells.
Why are the Islets of Langerhans well vascularised?
To facilitate rapid hormone release
What innervates the Islets of Langerhans?
Sympathetic and parasympathetic neurones
What does the Islets of Langerhans being innervated by sympathetic and parasympathetic nervous system imply?
There is a neurological contribution to pancreatic endocrine function
What happens when blood glucose levels rise after feeding?
Insulin is secreted
What does insulin do?
- Converts glucose to glycogen
- Facilitates cellular uptake of glucose
What happens when glucose is taken up by cells in response to insulin?
It is converted to glucose-6-phosphate
What happens when glucose levels fall during fasting?
Concentrations are maintained through secretion of glucagon
What does glucagon do?
Facilitates glucose production through glycogenolysis
What other hormones contribute to gluconeogenesis?
Other counter-regulatory hormones such as cortisol, growth hormone, and adrenaline.
How do other counter-regulatory hormones contribute to gluconeogenesis?
Through protein degradation and lipolysis
How is lipolysis facilitated when blood glucose levels fall?
By the switching off of insulin release
What transports triglycerides in the blood?
Very low density lipoproteins
What happens when triglycerides reach their target tissues?
Lipases promote hydrolysis of triglycerides into glycerol and free fatty acids
What happens to glycerol that is produced in lipolysis?
It is metabolised to rejoin the glycogenolysis and gluconeogenesis pathways
What happens to free fatty acids that are produced in lipolysis?
They are transported across the mitochondrial membrane to undergo a process of beta oxidation
What does the process of beta oxidation of free fatty acids produce?
Two carbon molecules of acetyl co-A
What happens to the carbon molecules of acetyl co-A after they are produced from free fatty acids?
They can enter the citric acid cycle to ultimately generate ATP
Why are young children at particular risk from hypoglycaemia?
- Relatively large brain size
- Limited glycogen stores
How is the risk of hypoglycaemia in young children compensated for?
Infants in particular are able to generate ketones as an alternative cerebral fuel more easily than adults
