Physiology: Endocrine Control of Metabolism: Nutting Flashcards
What happens to insulin after a meal?
Increases 3-6 fold
What does insulin do overall?
Promotes utilization and storage of glucose
Does glucagon have any peripheral effects?
No, it is mainly active at the liver.
The pancreatic vein goes directly to the portal system… anatomy!
What does glucagon do in the liver?
Promote breakdown of stored products and creating new glucose
What is the purpose of glucagon?
To keep glucose constant during fasting, mainly for our nerves
How long would our circulating glucose last without adding to it?
1 hour
How much time would the glucose in our livers supply us?
1/2 day
How much time would the glucose in our muscles supply us?
1 day
How many g glygoen stores of glucose is stored in liver and muscle?
100g liver
200g muscle
How much time would our fat stores last us?
30-40 days! Fat is the most efficient storage source.
What cells can only live on glucose?
Nerves
RBC
WBC
Renal tubules
What proportion of the glucose do nerves take of the cells who only use glucose?
3/4! 150g to 50g
What percent is muscle of body mass?
50%
What percent of energy does muscle use at rest?
30%
So effecting muscle metabolism has a big effect!
What does muscle prefer to burn?
FA
Ketones
rather than glucose and AAs
When is muscle glycogen utilized?
Heavy excercise
What organs have glycogen?
liver
kidney
muscle
What happens with muscle glycogen is depleted?
It doesnt work well.
What organ (other than pancreas) sees the highest concentration of insulin?
Liver
What organ is most responsive to insulin?
Liver
What are the objectives of the body during feeding?
- fill Glycogen stores
- dont spill much glucose in urine
- utilize carbs and fats for energy
- package excess for later (aa–>protein)
What are the main biochemical pathways SHUT DOWN during feeding?
Gluconeoenesis Glycogenolysis Lipolysis Ketogenesis Protein degradation
What is glucose’s effect in fat?
Esterify FA to store triglycerides
Stop making FA to ship
What are FA and ketones action in muscle during FASTING?
decrease Glucose utilization
Do FA and Ketones need insulin to get into tissues?
NO!
Why are FA stored in Fat? Why are they shipped?
Storage: esterified
Ship: not esterified
What are the objectives during fasting?
- Keep glucose constant for CNS
- Decrease glucose utilization elsewhere
- Keep some glycogen reserves
- Burn fat for FA and Ketones energy
- Utilize “sparable” proteins (AA (mainly alanine)) glycerol, and lactate, for gluconeogeneisis
Fat cells make FA and glycerol. What happens to they glycerol?
Gluconeogenesis in the liver
The liver makes glucose out of what in fasting?
Glycogen AA's (from muscle) Glycerol (from fat) ----- Lactate (from RBC) Pyruvate
What do Nerves, RBC, WBC make when they eat up the glucose?
Lactate
Pyruvate
What portion of FA is burned directly by cells that can use them? What portion burned as Ketones?
2/3 FA
1/3 Ketones
How large is the glycogenolysis between meals?
Only SMALL… we want to keep some
Mainly lipolysis and protein degradation
What are the short acting hormones of metabolism?
Insulin Epi NE Glucagon ****powerful and short=activity +/-
What are the long acting hormones of metabolism?
GH T3/T4 Glucocorticoids (Aldo) Sex steroids ****weak and long lasting=efficiency
Does GH go up or down in fasting?
Up
Does cortisol go up or down in fasting?
About steady… slightly down. Necessary for life.
Does SNS go up or down in fasting?
Up
Does T3 go up or down in fasting?
Down.
This is a protective action to decrease metabolism use of glucose.
What is normal fasting insulin level?
10
What is normal fed insulin level?
90
At what level does glucose equalize during fasting?
70
What happens to SNS during a meal?
Goes down
What hormones increase protein synthesis during a meal?
T3
GH
*insulin obviously…
What is very important about cortisol during fasting?
Is is PERMISSIVE to gluconeogenesis with Insulin/NE/E
What is important about GH during fasting?
It is permissive to lipolysis with NE/E
What synergizes with GH/Epi/NE to allow lipolysis during fasting?
T3
What short hormone is active in a meal?
Insulin
What decreases insulin secretion during a fast?
Epi and NE (not glucagon??)
What short hormone is active in a fast?
Glucose
NE/E
What are the moderators of Glucose production in liver?
+: NE/E/Glucagon/Glucocorticoids
-: Insulin
What are the moderators of glucose consumption in the muscle and fat?
+: insulin
-: Glucocorticoids/GH weak
(NOT E/NE/Glucagon!!!!)
What is effect of cortisol on glucose? TEST
Not direct. Weak alone. Permissive!
What is the effect of NE/E on glucose?
Increase more than glucagon
What is the effect of glucagon on glucose?
Increase more than cortisol
What is the effect of E/Glucagon
Synergistically higher
What is the effect of Cortisol/E/Glucagon
Permissively more synergistically higher! Highest!
Why is it so important to have cortisol once a day?
To allow glucagon and epinephrine to work to keep glucose levels high
What are the major lypolytic hormones?
NE/E–>cAMP–>lipase–>FA
What is the major antilipolytic hormone?
Insulin–>decrease cAMP
What makes NE/E more effective lipolitic? TEST
T3/T4
Cortisol
GH
What moderates glucose conversion to alpha glycerol (which becomes TG in fat)?
+: Insulin
-: GH, Cortisol (NOT T3…)
Decrease activity of Hormone sensitive lipase to do what?
Decrease FA production, decrease ketones
How long does lipolysis take via NE/E? GH?
NE/E=mins
GH=hours
How do Glucocorticoids promote permissiveness in the liver?
Increased syn:
Glycogen synthetase
G6Phosphatase
PEP CK
PE Carboxylase (PC) (shung Pyruvate up)
Transaminase (shunt AAs up)How do Glucocorticoids promote permissiveness in the periphery?
Muscle: Increase AA release by decreased PS
Fat: increase Glycerol release (works with GH and T3)
What do PEPCK and PC do in liver?
Shunt pyruvate back up to G6P for gluconeogenesis ship out
What does G6Pase do in liver?
Locks G in, sends G out
What does Glucocorticoid increase in AA breakdown cause?
Urea formation: increase BUN
Glucocorticoids in liver are permissive for:
Gluconeogenesis
Lipolysis
What happens to plasma glucose in exercise?
Stays same
What happens to muscle glucagon in exercise?
Down
What happens to FA in exercise?
UP
What happens when you “hit the wall” in exercise?
Muscle is out of glycogen
What are the hormone changes in extended moderate exercise?
+: Up: GH, Cortisol, Glucagon, NE, Epi
-: Down: Insulin
Test: What keeps us from dying of hypoglycemia?
- Eat
2. Get glucose into cells: insulin
What glucose level stops insulin? Starts G/G/E? C? Symptoms?
80
70
60
50
Cortisol is increased by what 2 hormones?
CRH
ACTH
At what glucose level does the liver increase gluconeogenesis even without hormones?
47… 45 is cognition error…
