Chapter 6: Endocrine Control of Metabolism & Diabetes Flashcards
feul metabolism
chemical reactions that occur within the cells
Intermediary metabolism
reactions involve the degradation, synthesis, and transformation of protein, carbohydrates, and fats
proteins are converted into
amino acids
CHO is converted to
monosaccarides (glucose)
Triglycerides are converted to
fatty acids and monoglycerides
what are the absorbable units
- monoglycerideds
- amino acids
- fatty acids
glucose and amino acids are transported via
blood
fatty acids are transported via
lymph
metabolism
- all chemical reactions occurring within the cells of the body
- involve degration, synthesis, and transformation reactions
Anabolsim
- builder larger organic macromolecules from smaller molecular subunits
- requires ATP
example of anabolism
6H2O + 6CO2 –> C6H12O6
Catabolism
- degration of the large energy rich organic molecules within the cells
- uses hydrolysis
catabolism reaction
C6H12O6 –> 6CO2 + 6H2O
glycogenesis
Glucose –> glycogen
- decreases blood glucose
Glycogenolysis
Glycogen –> glucose
- increases blood glucose
Gluconeogenesis
Amino acids –> glucose
- increases blood glucose
protein synthesis
Amino acids –> protein
- decreases blood amino acids
Fat synthesis (Lipogenesis or triglyceride synthesis)
Fatty acids and glycerol –> triglycerides
- increases blood fatty acids
protein degration
protein –> amino acids
- increases blood amino acids
Fat breakdown (Lipolysis or triglyceride degradation)
Triglycerides –> fatty acids and glycerol
- increases blood fatty acids
how are amino acids stored
body proteins (muscle)
how is glucose stored
as glycogen in the liver and muscle
how are fatty acids stored
in adipose tissue
excess amino acids are excreted through
- the urea
- used as metabolic fuel
excess glucose is excreted through
- metabolic fuel
excess fatty acids are excreted through
metabolic fuel
absorptive / fed state
- metabolic fuels are stored
- nutrients are absorbed into the lumen
- glucose is a MAJOR nutrient and severs and the bodys major energy source (plentiful as serves as major energy source)
post absorptive state / fasting state
- metabolic fuels (endogenous energy stores) are mobilized to provide energy to the brain
- glycogenolysis and glucose sparing
- synthesis of proteins and fats are inhibited
liver
- primary role in maintaining normal blood glusoe levels
- principle state for metabolic interconversion
Adipose tissue
- primary energy storage site
- important in regulating fatty acid levels in the blood
Muscle
- primary site of amino acid storage
- major energy user
brain
- normally can only use glycogen as an energy source
- does not store glycogen (mandatory glucose levels must be maintained)
triglyceride conversion to glucose
triglyceride –> hydrolysis –> glycerol –> glucose
how is lacitic acid made
Glycolysis –> incomplete catabolism –> glucose –> muscle –> lacitic acid
ketone bodies
- produced by the liver during lgucose sparing
- serve as an alternate energy source for tissue and produced through the citric acid cycle
when does the body use ketones as their major energy source
during long term starvation
ketone bodies process
liver –> fatty acids –> Acetyl CoA –> ketone bodies –> blood
nutrients alon the metabolic pathway are influenced by these 5 hormones
- insulin
- glucagon
- epinephrine
- cortisol
- GH
insulin and glucagon shift the metabolic pathways in feasting and fasting states to
from net anabolism to net catabolism and glucose sparing
Pancreas endocrine gland
islets of Langerhans
pancreas b cells
site of insulin synthesis and secretion
pancreas A cells
produce glucagon
Insulin and glucogon
are most important in regulating feul metabolism
Insulin
- decreases blood glucose
- promotes cellular reuptake and converts and stores
when is insulin secreted
when there are high levels of blood glucore
Insulin exerts its effects by
- “altering transport” of specific blood borne nutrients to the cell
- altering the activity of the enzymes involved in specific metabolic pathways
Insulin regulates there 6 functions
- Glucose reabsorption from the GI tract
- transport of glucose into cells
- hepatic production of glucose
- urinary excretion of glucose
- stimulates glycogensis
- inhibits glycogenolysis (decreases heptic glucose production)
Action of insulin
inhibits enzymes that covert the amino acids into glucose
promotes reuptake
how is glucose transported in the blood
glucose transport carrier (GLUT)
how many forms of GLUT are there
6
GLUT-1
crosses glucose across the BBB
GLUT-2
transfers glucose from kidneys and intersticial cells into the bloodstream
GLUT-3
transfers glucose into neurons
GLUT 1 and 3
transports glucose to the brain
GLUT-4
- present in the plasma membrane of tissues such and skeletal muscles and adipose tissues
GLUT 4 is only responsive to
insulin
- induces “intracellular vesicles”
- promotes 10-30 fold
what tissues do not depend on insulin for glucose uptake
- brain
- working muscles
- liver
Action of insulin on fats
lowers blood fatty acids and promotes their storage as triglycerides
- increases glucose transport through GLUT-4 recruitment
-activates enzymes that catalyze the production of glucose from fatty acids
- inhibits lypolysis
action of insulin on proteins
- lower blood amino acid levels and enhances protein synthesis
- promotes active transport of amino acids from the blood to the muscles and tissues
- enhances amino acid incorporation into protein by stimulating the cells protein synthesizing machinery
- inhibits protein degration
In case insulin secretion is high
- stimualte biosynthestic pathways to increase CHO, fat, and protein storage
- lower blood glucose, fatty acid, and amono acid levels
- insulin level in the blood increases following meals injestions
- enhances net metabolsim
in case insulin secretion is low
- rate of glucose entry into the cells reduced
- net catabolism occurs rather than the net synthesis og glycogen, triglycerides, and proteins
- characteristic of post-absorptive state
negative feeback between insulin and glucose
meal –>pancreas –> b cels –> insulin –> blood –> glucose –> b cells
what 4 factors influence insulin
- increase gastrointestinal hormones
- paraymptatetic stimulation
- increased blood amino acid concentration
- sympathetic stimulation (and epinephrine)
glucose-dependent insulinotropic peptide (GIP) effect
- insulin in a feed forward reaction
- activates in the presence of CHO rich meal
Effect of the parasympathetic NS
insulin release
effect of sympathetic NS
epinephrine release
glucagon is secreted by
alpha cells of the pancreas
what is the major site of action for glucagon
liver
action of glucagon on CHO
- activates in response to low blood glucose during starvation
- increases blood glucose levels
Action of glucagon on fats
acts during low glucose levels during starvation
antagonizes insulin action by:
- promoting the breakdown of fat
- inhibiting triglyceride synthesis
- enhancing heptic ketone productions
action of glucagon on proteins
acts in response to low blood glucose during starvations
- stimulates gluconeogenesis
- stimulates protein catabolism in the liver
- inhibits heptic protein synthesis and promotes degration of heptic proteins
role of epinephrine and cortisol on metabolism
- increases blood glucose and fatty acids
- during stress, cortisol mobilizes amino acids through protein catabolism
- during long term starvation, cortisol helps to maintain glucose concentration
role of GH on metabolism
- excerts anabolic effects due to its growth promoting effects
- elevates the blood glucose and fatty acids
- helps maintain glucose level during starvations
during deep sleep, stress, exercise and severe hypoglycaemia what hormone is activated to provide fatty acids as an alternate energy source
GH
TH effect on metabolism
- increase overall metabolic rate
- has both catabolic and anabolic effects
why is TH NOT important for fuel metabolism
- control of TH secretion is not directed toward maintain nutrient levels in the blood
- the onset of TH action is too slow to have any significant effect on rapid adjustments required to maintain normal levels of nutrients
what is the most common endocrine disorder
diabetes
acute symptoms of diabetes can be attributes to
an inadequate insulin level
symptoms of diabetes
- large urine volume
- thirst
- polyphagia
- polyurea
- fatigue
- polydipsia
- dehydration
- renal and peripheral circulatory failure
level of insulin secretion in type I diabetes
none or almost none
level of insulin secretion in type 2 diabetes
may be normal or exceed normal
thypical onset of age for type 1 diabetes
childhood
typical onset of age for type 2 diabetes
adulthood
what percentage are type 1 diabetics
10-20%
type 1 diabetes basic defect
autoimmune distruction of B cells
type 1 diabetes treatment
insulin injections; dietary management; excersize
what percentage of diabetics of type 2
80-90%
type 2 diabetes basic defect
reduced sensativity of insulin target cells
type 2 diabetes treatment
- dietary control and weight reduction
- excersize
- sometime oral hypoglycemic drug
Review diabetes symptoms chart
