M104 T2 L6 Flashcards
(52 cards)
What happens during immediate ‘absorptive’ events?
Liver and adipose tissue mainly take up materials
import
What happens during post-absorptive events?
the cells of the liver and adipose tissues between meals
export
What part of the body is most vulnerable to hypoglycaemia and why?
the brain
as cerebral cells derive their E predominantly from aerobic metabolism of glucose
How do cerebral cells store glucose?
They can’t store it in significant amounts or synthesise it
Why can’t cerebral cells extract sufficient glucose for their needs from ECFs at low concs?
bc glucose entry into the brain is not facilitated by hormones
What is the greatest reserve of E stores in the body?
TGCs
How much glucose is contained in blood?
10g
What is the total body usage of blood glucose per day?
about 200g / day
160g of this is for the brain and RBCs
What mechanisms are responsible for increased blood glucose?
gluconeogenesis
glycogenolysis
dietary intake
What mechanisms are responsible for decreased blood glucose?
Glycogen and Fat Synthesis
Glycolysis
Where does gluconeogenesis occur?
in the liver and kidneys
What substances are responsible for increasing the bg level?
glucagon
catecholamines
cortisol
growth hormone
What is the value for average plasma glucose levels?
between 2.5-8mM
From where is glucose absorbed following a meal, and how long after said meal?
from the intestine
2-3 hours following a meal
How long does glycogen last?
12-24 hours
What happens during sleep or during extended food deprivation?
there is a gradual dependence on de novo glucose synthesis by gluconeogenesis
Does bg levels change during the day?
bg varies relatively little throughout the day or night despite changes in food intake
What has a major and very important metabolic effect on insulin?
Glucose entry into cells
How do polar molecules enter cells across a lipid membrane?
via passive or active transport
How does glucose enter cells?
by facilitated diffusion - a carrier-mediated process
What are the family of glucose transporter proteins involved in glucose entry?
involves Gluts
they are structurally related but encoded by different genes that are expressed in tissue specific manner
Where are the five different Glut proteins found?
Glut 1 - in many tissues
Glut 2 - in the liver, pancreatic B cells
Glut 3 - in brain
Glut 4 - in the skeletal muscle, adipose tissue (Insulin-sensitive)
Glut 4 - in the SI , fructose transporter
What are examples of locations where Glut 1 is found?
erythrocytes, muscle, brain, kidney, colon, placenta, foetal tissue
What do all cells express?
at least one transporter isoform constitutively as a certain level of glucose uptake is an absolute necessity
