Lecture 14 4/3/25 Flashcards
(45 cards)
What is glucose homeostasis?
process by which the body maintains a stable level of glucose in the blood to ensure proper cellular function
What is the typical normal range for blood glucose?
80 to 120 mg/dL
What are the characteristics of the brain and glucose?
-steady glucose supply is essential for cerebral cortex and cerebellum function
-brain is an obligate glucose user
-does not require insulin
-has minimal glycogen stores
-cannot use ketone bodies or fatty acids for energy
What are the characteristics of GLUT?
-14 different types
-ubiquitous
-sodium and ATP-independent
What are the characteristics of sodium-glucose-co-transporters/SGLT?
-sodium-dependent
-require ATP
-found in the renal tubules, intestines, and BBB
What are the characteristics of SGLT-2?
-responsible for greater than 90% of glucose reabsorption
-high capacity
-low affinity
What are the characteristics of SGLT-1?
-responsible for less than 10% of glucose reabsorption
-low capacity
-high affinity
How can food act as a source of glucose?
-direct uptake of glucose from food by cells for cellular functions
-storage of glucose as glycogen in liver and muscle
-storage of glucose as triglycerides in fat
What are the characteristics of glycogen?
-produced through glycogenesis; process of synthesizing glycogen from glucose that requires insulin
-highly branched starch
-primarily stored in liver; also found in skeletal muscle
Why is it important that insulin inhibits hormone-sensitive lipase?
this allows for triglycerides to be stored rather than broken down
What is gluconeogenesis?
process done by the liver in which glucose is produced from end-products of glycolysis or Krebs cycle intermediates
Which molecules CANNOT be used for gluconeogenesis?
fatty acids
What are the characteristics of glycogenolysis?
-breakdown of glycogen into glucose
-leads directly into the Krebs cycle, a major energy yielding metabolic pathway
Why do animals not become hypoglycemic with simple fasting?
-liver can maintain normal blood glucose
-glycogenolysis stimulated by glucagon maintains BG for first 24 hours
-gluconeogenesis maintains BG after 24 hours of fasting
Why are young animals and smaller breeds more at risk for hypoglycemia?
they have limited glycogen stores, which makes it more difficult to maintain blood glucose when fasting
What is lipolysis?
process of breaking down triglycerides into fatty acids to provide energy
What do the hepatic mitochondria do with fatty acids?
use them to produce ketone bodies, an alternate energy source to glucose
What are the potential benefits of a ketogenic diet?
-weight loss
-improved glycemic control
-reduced inflammation
-increased energy
How does a lack of insulin affect diabetics in terms of energy source?
-body shifts to using fat for energy instead of glucose due to lack of insulin
-fat breakdown leads to ketone formation and diabetic ketoacidosis
What are the functions of the liver as a regulatory organ for energy?
-glycogenesis
-glycogen storage
-glycogenolysis
-gluconeogenesis
-ketogenesis
What are examples of conditions that can cause liver dysfunction and subsequent hypoglycemia?
-portosystemic shunt
-acute liver failure
-chronic liver disease
Which hormone decreases blood glucose?
insulin
Which hormones are counter-regulatory hormones and increase blood glucose?
-cortisol
-epinephrine
-growth hormone
-glucagon
What are the characteristics of cortisol?
-produced by the zona fasiculata and zona reticularis of the adrenal cortex
-has delayed production
-effects last for hours
-stimulates hepatic gluconeogenesis
-decreases uptake and use of glucose by peripheral tissues
