Download MBBS (Bachelor of Medicine, Bachelor of Surgery) 1st year (First Year) Biochemistry ppt lectures Topic 57 Biochemistry Of Starvation Notes. - biochemistry notes pdf, biochemistry mbbs 1st year notes pdf, biochemistry mbbs notes pdf, biochemistry lecture notes, paramedical biochemistry notes, medical biochemistry pdf, biochemistry lecture notes 2022 ppt, biochemistry pdf.
Can Any One Guess
Todays Topic Of Discussion?
Biochemistry Of
Starvation
What Is Starvation?
?Starvation is
complete stoppage
of eating food by a
human body.
What Is Total Starvation?
?Total starvation is
complete stoppage
of Food and Water.
Conditions Developing Starvation
? Food Scarcity
(Natural Calamities , Draughts Floods and ,Famines)
? Extreme Poverty
? Lost in Sea routes for long durations
? Clinical Conditions: Major Surgeries, Severe Burns.
? Desire to loose rapid weight
? Political Issues: Hunger Strikes
Features Of Starved Body
? No entry of exogenous food constituents
? Body in starvation is deprived of:
?Calories (Carbs and Lipids)
?Building blocks (Proteins)
?Growth Factors(Vitamins and Minerals)
?Protectors (Antioxidants)
During
Starvation
the body
is under
Metabolic Stress
?During Starvation the
body is in an emergency
condition
?Starved body has to get
adapted
?And Manage with
Endogeneous reserve
stores.
Survival Period During Starvation
? Survival period during Starvation
depends upon the:
? Reserve Fat stores in Adiposecytes.
?More content of TAG in Adiposecytes
?More is the duration of survival in
Starvation and vice a versa.
Length Of Survival In Starvation
? Due to deprivation of only Food:
?3 to 4 Weeks
?Longer up to 65 days
? Deprivation of water alone then
survival is only for few days
?Less than a week
Effects Of Starvation
OR
Human Body Adaptation In
Starvation
Biochemical Alterations In
Starvation
During Starvation
? No exogenous Food source ingested
? Food Nutrients get deprived
? Body is in an emergency condition
? Metabolic stress is developed
? Body manages and adapts to live on
the endogenous fuel stores.
? Alterations in metabolic/biochemical
processes
? The biochemical alterations during
Starvation are influenced by hormonal
actions.
? Glucagon and Epinephrine in starvation
act upon the target organs
? Stimulate metabolic pathways which
supply fuels and
? Improve survival phase during
Starvation.
Different Modes
To Study Biochemical Adaptations
During Starvation Phases
Study Of Biochemistry Of Starvation
With Respect To
?Stages
?Metabolism
?Organs
Occurrence Of
Four Stages During Starvation
OR
Metabolic Alterations During
Starvation
Stages
Metabolic Process
First Stage
Increased Glycogenolysis
Second Stage Increased Gluconeogenesis
Third Stage
Increased Lipolysis/Fatty
acid Beta Oxidation
Fourth Stage
Increased Ketogenesis
Alternative Adaptations
In Different
Metabolic Processes
During Starvation
Hormonal Alterations In Starvation
? Insulin secretion
decreased
? Glucagon and Epinephrine
increased
Hormonal Influences In Starvation
Hormone
Source
Change in
Secretion
Norepinephrine Sympathetic
Nervous System
Norepinephrine Adrenal Gland
Epinephrine
Adrenal Gland
Thyroid
Thyroid Gland
Hormone T4
(changes to T3
peripherally)
? When food is in Short supply
? Metabolic activity decreases
to spare fuel.
? Conservation of energy is one
of the basic adaptive
responses to calorie reduction
? The Hormones influences
the utilization of
endogenous reserve stores
and
? Supply fuels to body
organs during starvation
phase.
?Norepinephrine and T3
participate to
?Decrease in metabolic
activity when calorie
intake decreases.
Biochemical Adaptations Of
Carbohydrate Metabolism
During Starvation Phase
Carbohydrate Metabolism
In Liver During Starvation Phase
? Glycogenolysis Increased
? Glycogenesis Decreased
? Gluconeogenesis Increased
? Glycolysis Decreased
? TCA operation Decreased
? HMP Shunt Decreased
? Blood Glucose level Decreases (later stages)
? Cellular Glucose Deprivation (In Muscle Cells)
?PDH a Multi Enzyme
Complex is inhibited
during Starvation.
Biochemical Alterations of
Lipid Metabolism In Starvation
Lipid Metabolism During Starvation
? Lipolysis is Increased
? Mobilization of Free Fatty acids increased
? Beta oxidation of Fatty acids increased
? Incomplete Fatty acid Oxidation increased
? Ketogenesis Increased
? Ketolysis Decreased
? Ketosis Noted (Ketoacidosis)-Rotheras Test +ve
? Lipogenesis is Decreased
?Enzyme Acetyl Carboxylase
is inhibited during
Starvation.
Increased Ketogenesis In Starvation
What Happens? When Ketone body production
Exceeds than the Ketone body Utilization?
? When?
? Cellular Glucose deprivations occurs in
? Uncontrol ed Diabetes
? Prolonged Starvation
? Ketosis
? High levels of Ketone Bodies in blood and urine
? Ketoacidosis
? Severe ketosis
? Lowered blood pH,
? Nausea ,Acetone breath
? Coma, Death
Cure For Ketosis
? Ketosis Cured by infusion of
Glucose.
Alterations In Protein Metabolism
During Starvation
During Starvation
? Catabolism Of Muscle Proteins
increased
? Transdeamination reaction of
Amino acids is increased
? To release Glucogenic amino
acids
? Ammonia Detoxification and
Urea production increased
initial y and decreased as
Starvation phase prolongs.
? Body is in negative Nitrogen
Balance.
? Concentration of Functional
Proteins Decreases.
Glucose Nitrogen Ratio
Increased In Starvation
During Starvation
Alterations Occur In
Water and Electrolyte
And
Acid Base Balance
? Reduction in Body Water
? Reduction of Potassium
ions
? Acidic blood pH due to
increased Ketone bodies
?On prolonged phase of
Starvation there results
?Severe dehydration and
Acid Base imbalance
Alterations In BMR
?BMR is first affected in
starvation.
?In starvation BMR is
Decreased.
Biochemical Adaptations By Organs
During Starvation
The Fasting State:
Glucagon stimulates glucose
production and release in liver.
Also mobilizes the fatty acids
(sparing Glucose for the Brain)
Differentiation In
Well Fed And Fasting States
Of Human Body
WELL-FED STATE
FASTING STATE
Hormones
Insulin
Glucagon,
Adrenaline, Cortisol
Hyperglycemia
Hypoglycemia
Response of
Glycogenesis
Lipolysis
the body
Lipogenesis
Ketogenesis
Protein synthesis
Proteolysis
WELL-FED STATE
FASTING STATE
Source of
from stores
(Glycogen)
Glucose
from food
Gluconeogenesis
Fate of
Glycolysis
Glucose
formation of Glycogen and
Glycolysis
TAG stores
WELL-FED STATE
FASTING STATE
Source of
from food TAG
from storage TAG
Fatty acids
-oxidation
Fate of Fatty
-oxidation
(Incomplete one)
acids
synthesis of TAG and
Store as Depot Fat
Ketogenesis
WELL-FED STATE
FASTING STATE
Source of
Amino acids
from food
From muscle Proteins
Glucogenic amino
Fate of
Protein synthesis
acids
Amino acids
Produce Glucose via
Gluconeogenesis
Preferred fuels By Human body
In the Well-Fed and Fasting States
Organs
Well-Fed
Fasting
Liver
Glucose & Fatty
Fatty acids
acids
Resting skeletal
Glucose &
Fatty acids & KB
Muscle
Fatty acids
Cardiac muscle
Fatty acids
FA,AA & KB
Adipose tissue
Glucose
Fatty acids
Brain
Glucose
Glucose ,Later KB
RBCs
Glucose
Glucose
BIOCHEMICAL PROFILE OF EARLY FASTING STATE
Blood Glucose levels decreases
65 mg/dl
Active Glycogenolysis
Muscle and Liver
Shift of metabolic fuel from Glucose to fatty
acidsFatty acid mobilization from adipose tissues
Gluconeogenesis
Glucose Alanine cycle
BIOCHEMICAL PROFILE OF STARVED STATE
GLUCOSE levels more decreased
40 mg/dL
PROTEIN CATABOLISM increased
Sequesters Nitrogen as urea
Excretes 20 to 30 grams daily
Gluconeogenesis taking place using precursors as
Amino acids
Lactate
Glycerol
KETONE BODIES increased
Acetyl CoA converted to ketone bodies via Ketogenesis
In Prolonged Starvation
? After 3 days of Starvation -> Liver
forms large amounts of Ketone
bodies
( Due to shortage of Oxaloacetate)
? Ketone Bodies -> released into blood
? Brain and Heart start to use ketone
bodies as fuel during phase of
Starvation.
Starvation Of Several Weeks
? After several weeks of starvation ->
Ketone bodies become major fuel of
Brain
? After depletion of TAG stores
? Proteins degradation accelerates
? Death due to loss of Heart, Liver,
and Kidney function.
FUEL CHOICE DURING STARVATION
1. Insulin
6. Ketone bodies
5. Fatty acids
2.Glucagon
nge
3 .Glucose
l
a
t
i
v
e
cha
Re
4. Glycogen
24
Hours of Starvation
Changes Of Liver Glycogen Content
During Starvation
? Fuel changes from Glucose to Fatty acids to
Ketone bodies
Metabolic Response To Fasting
Fasting ? Early Stage
Muscle
Alanine / Pyruvate
Brain
Glucose
Glutamine
Glycerol
Gluconeogenesis
Ketogenesis
Ketones
Fat
AGL
Liver
Ureagenesis
Ketones
Urea
NH3
Kidney
Intestine
Fasting ? Late Stage
Muscle
Alanine / Pyruvate
Brain
Glucose
Glutamine
Glycerol
Gluconeogenesis
Fat
Ketogenesis
Ketones
AGL
Liver
Ureagenesis
Ketones
Urea
NH3
Kidney
Intestine
Energy Expenditure in Starvation
12
a
y
)
n
(
g
/d
8
Normal Range
x
c
r
e
t
io
4
Partial Starvation
N
it
r
o
g
e
n
E
Total Starvation
0
10
20
30
40
Days
Long CL et al. JPEN 1979;3:452-456
Consequences Of Starvation
? Severe Malnutrition
? Damages and affects vitality of Important Internal Organs
? Decreased BMR
? Night blindness (Vitamin A deficiency)
? Scurvy (Vitamin C deficiency)
? Irregular Menses
? Constipation
? Low Immunity
? Bone Loss
? Anaemia (Iron and Protein deficiency)
? Fatigue
? Dehydration
? Water Electrolyte Imbalance
? High Blood Pressure
? Brain Defects
? Death
Questions
? Explain the different stages of
starvation & biochemical alterations
in the body during these stages.
OR
? Biochemical alterations/adaptations
during starvation.
? Describe the role of following
organs during various stages of
starvation
? Liver
? Brain
? Muscles
? Adipose tissues
THANK YOU
This post was last modified on 05 April 2022