Unit 8 Flashcards
Integration level- flow of key metabolites between different pathways
Cellular level
Integration level- interdependence of different organs and tissues
Tissue and organ level
Major metabolic fuel
Glucose
What is the storage form of glucose?
Glycogen
Cells that contain _________ can generate glucose and send to the blood stream.
Name some examples
Glucose 6-phosphate.
Liver, kidney, and small intestine
Other sources of glucose
TAGs and glucogenic amino acids- used for gluconeogenesis
What carries nutrients to the liver?
Portal vein
______ turn nutrients into fuel
Hepatocytes
What causes enzymes to increase or decrease?
Changes in diet
Needs of other tissues
What allows for passive diffusion of glucose in and of the blood? Found in hepatocytes
GLUT2
What is the glucose phosphorylating enzyme?
Glucokinase (Hexokinase IV)
What makes glucokinase soo special?
It has a higher Km (10mM) than other kinases (4mM)
When is glucose-6-phosphate not made? Why?
When glucose is low
other tissues need the glucose?
Where is GLUT2 found?
In the liver and pancreas
What are the monosaccarides in the liver that can convert into glucose-6-phosphate?
Fructose, galactose, and mannose
What are the potential fates of glucose-6-phosphate in the liver?
1- It is dephosphorylated by glycogen phosphorylase (yields free glucose to send to other tissues)
2- Makes glycogen with phosphoglucomutase
3- Enter glycolysis to make Acetyl-CoA for FA biosynthesis
4- Enter glycolysis pathway to make acetyl-CoA for ATP generation
5- Enter Pentose phosphate pathway to yield NADPH
Glucose-6-phosphate metabolism generates nucleotides and reductive biosynthesis power in the form of ______ via what pathway?
NADPH
Pentose phosphate pathway
Potential fates of amino acids in the liver:
1- Biosynthesis of proteins for the liver and other tissues
2- Biosynthesis of hormones and nucleotides
3- Biosynthesis of CAC intermediates or pyruvate for gluconeogenesis
What is pyruvate converted to acetyl CoA?
For liver cell energy and conversion to lipids
Potential fates of fatty acids in the liver:
1- Synthesize liver lipids
2- Oxidize to acetyl-CoA and NADH
3- Convert to phospholipids
4- Convert to TAGs for storage
5- Carried to heart and muscle for oxidation
Fate of Acetyl-CoA in the liver:
1-Sent thorugh CAC and oxidative phosphorylation to make ATP
2- Some is converted into cholesterol, which in turn becomes either bile salts or steroid hormones in the blood
3- Excess Acetyl-CoA is converted to ketone bodies for the brain and heart in carbohydrate restriction and fasting
Free fatty acids in the blood bind to what?
Albumin
Ketone bodies include: (3)
Beta-hydroxybuterate
Acetoacetate
Acetone
When are ketone bodies made?
when oxaloacetate pools are insufficient to condense with acetyl-CoA
Why are ketone bodies able to enter the brain?
they do not bind to albumin
Ketone bodies are _____ for energy in place of, or to supplement ____.
oxidized
glucose
% of ketone bodies that supply energy for the brain:
For the heart:
70
30
Liver functions: (4)
Provide glucose and ketones for other organs
Process amino acids into urea, etc
Store nutrients (iron, fat soluble vitamins)
Detoxify and solubilize organic compounds via cytochrome P45 system
Adipocyte function: (4)
Carry out glycolysis though oxidative phosphorylation
Convert acetyl-coa into fatty acids
Use FA to make TAGS
Release FA when other tissues need them
FA make TAGS from ______ found in intestinal lipids
and ____ found in the liver
chylomicrons
VLDL
What does skeletal muscle use for energy?
glucose
FA
Ketone bodies
What does resting skeletal muscle rely on for energy?
fatty acids
what do active skel muscle rely on for energy?
glucose and ketone bodies
What muscle type is rich in mitochondria and is fed by many blood vessels?
How does it provide energy?
Slow-twitch muscles
via slow and steady oxphos
What muscle type has fewer mitochondria and has lower O2 delivery?
Fast-twitch muscle (aka white muscle)
why do fast twitch muscles use ATP faster and fatigue faster?
Due to greater demands (more tension), combined with reduced O2 delivery
What can increase mitochondria in skel muscle?
endurance training
Sources of glucose and ATP for skel muscle
Muscle glycogen -> glucose 6-phosphate
phosphocreatine
muscle glycogen -> glucose-6-phosphate yields # ATP
why?
3 (opposed to glycolysis making 4)
glycogen breakdown skips ATP dependant hexokinase reaction
Pyruvate->lactate creates _____ to enable _____ to continue
NAD+
glycolysis
Phosphocreatine acts on _____ ____ to release _____. Another biproduct released is:
creatine kinase
ATP
Creatine
During muscle contraction, lactate is produced ______.
CO2 is from ____ ___.
anaerobically
aerobic oxidation
Epinephrine cascade stimulates ____ ____. It breaks down:
glycogen phosphorylase
glycogen in muscle and liver
What is O2 debt?
continued rapid breathing after vigorous exercise. This is bc O2 is still needed for oxphos to make ATP.
(ATP is then used for gluconeogenesis to use up lactate and replenish muscle glycogen)
Heart or skeletal muscle- which has more mitochondria?
heart
What does the heart muscle primarily use for fuel?
fatty acids (although it does use some ketones, glucose and phosphocreatines
The heart is an (AEROBIC/ANAEROBIC) organ.
What does this mean?
aerobic
if O2 suppy is cut off, the muscle dies (myocardial infarction)
Metabolic cooperation between the skel muscle and liver
Cori cyle
Overall cori cycle pathway:
Glucose -> lactate -> glucose
What ketone body is used for the brain during starvation?
beta-hydroxybuterate
What maintains the transmembrane potential essential to information transfer among neurons?
elecrogenic transport by the Na+K+ATPase
____ of the nervous system can use fatty acids for energy
astrocytes
ATP is used to maintain ___ ____ across membranes of neurons. Especially:
electrical potential
NA+K+-ATPase
What stimulates glucose intake in muscle and fat? Pathway?
Insulin
glucose->glucose-6-phosphate
In the liver, insulin stimulates ___ ____ and ____, and inactivates ____ ____.
glycogen synthase and glycolysis
glycogen phosphorylase
What stimulates TAG synthesis in the fat and liver/
insulin
Insulin is an ____ hormone, except for:
anabolic
glycolysis
How is NADH necessary for lipid synthesis obtained?
by oxidation of glucose in the pentose phosphate pathway
Dietary fats move via the ___ system as ____ from the ____ to the liver, muscle and adipose tissue
lymphatic
chylomicrons
intestine
