Download MBBS (Bachelor of Medicine, Bachelor of Surgery) 1st year (First Year) Biochemistry ppt lectures Topic 37 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.
Induction To Todays Topic
Can Any One Guess
Todays Topic Of Teaching and
Learning?
Biochemistry Of
Starvation
Specific Learning Objectives
? What is Starvation?
? Which Conditions develop Starvation?
? What are Stages/Phases of Starvation?
? Which Hormones play imp role in starvation?
? Factors of Biochemical adaptation in Starvation
? How Organs adapt to Starvation?
? What are Consequences 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
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
During
Starvation
Body
is under
Metabolic Stress
Features Of Starved Body
? No entry of exogenous food nutrients
? Starved body is deprived of:
?Calories (Carbs and Lipids)
?Building blocks (Proteins)
?Growth Factors(Vitamins and Minerals)
?Protectors (Antioxidants)
Biochemical Adaptations
During Starvation
Important Factors Responsible For
Adaptation In Starvation
? Content Of Endogenous Stores
? Health of Associated Organs and System
? Associated Metabolic Processes involved with:
?Hormones
?Enzymes
?Coenzymes
? During Starvation a body is in an
emergency/critical condition
? Has to face Biochemical Chal enge
? Has to get adapted
? Manage with endogenous metabolite
reserve stores
? Communicate and Cooperate through
hormones
?Overcome state by biochemical alterations
?Try Survive as per condition
Survival Period During Starvation
? Survival period during Starvation
depends upon :
? Reserve TAG stores of Adiposecytes:
?More content of TAG in Adiposecytes
?More is 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
Different Modes
To Study Biochemical
Adaptations
During Starvation Phases
Study Of Biochemistry Of Starvation
With Respect To
?Stages
?Metabolism
?Organs
Alternative Adaptations
In Different
Metabolic Processes
During Starvation
Occurrence Of
Four Stages During Starvation
OR
Metabolic Alterations During
Starvation
Starvation
Metabolic Alterations
Stages
1
Increased Glycogenolysis
2
Proteolysis
Glucose Alanine Cycle
Increased Gluconeogenesis
3
Increased Lipolysis
Fatty acid Beta Oxidation(Incomplete)
4
Increased Ketogenesis
Ketosis
Fasting ? Early Stage
Muscle
Alanine / Pyruvate
Brain
Glucose
Glutamine
Glycerol
Gluconeogenesis
Fat
Ketogenesis
Ketones
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
Role Of Hormones In Starvation
? When food is in Short supply
? Metabolic activity decreases
to spare fuel.
? Conservation of energy is
basic adaptive response to
calorie reduction
? Hormones influences an
utilization of endogenous
reserve stores and
? Supply fuels to body
organs during starvation
phase.
Hormonal Alterations In Starvation
? Insulin secretion
decreased
? Glucagon and Epinephrine
increased
Metabolic Role Of Hormones
Hormonal Influences In Starvation
H ormone
Source
Change in
Secretion
Norepinephrine Sympathetic
Nervous System
Norepinephrine Adrenal Gland
Epinephrine
Adrenal Gland
Thyroid
Thyroid Gland
Hormone T4
(changes to T3
peripherally)
?Norepinephrine and T3
participate to
?Decrease metabolic
activity when calorie
intake decreases.
? Thus biochemical alterations during
Starvation are influenced by hormonal
actions.
? Glucagon and Epinephrine in starvation
act upon target organs
? Stimulate metabolic pathways which
supply fuels
? Improve survival phase during
Starvation.
Metabolic Alterations In Starvation
Biochemical Alterations Of
Carbohydrate Metabolism
During Starvation Phase
Carbohydrate Metabolism
In Liver During Starvation Phase
? Glycogenolysis Increased
? Glycogenesis Decreased
? Glucose Alanine Cycle increased
? 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
Alterations In Protein Metabolism
During Starvation
Proteins Serve as Calorific
During Starvation
? Muscle Proteins are catabolized to provide
carbon skeleton for Liver Gluconeogenesis
? Liver Gluconeogenesis increased via Glucose
Alanine cycle regulates blood Glucose levels
? Glucose produced initially via Gluconeogenesis
to Brain and Erythrocytes
Protein Metabolism During Starvation
? As Glucose levels lowers in blood
? Catabolism Of Muscle Proteins
increased
? Transdeamination reaction of
Amino acids is increased
? To release Glucogenic amino acids
? Glucose Alanine Cycle elevates
? 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.
Nitrogen Excretion 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
Glucose Nitrogen Ratio
Increased In 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
Levels Of Ketone Bodies
Increases
As
Starvation Phase Prolongs
Increased Ketogenesis In Starvation
What Happens? When Ketone body production
Exceeds than the Ketone body Utilization?
? When Prolonged Starvation ?
? Cellular Glucose deprivations occurs
? Glycogen stores depletes within 24 hrs of fasting
? Fat burns under flame of Carbohydrates
? Fatty acid are incompletely oxidized
? Acetyl-CoA of fatty acid oxidation is metabolized to
ketone bodies and mobilized out of Hepatocytes
? Ketogenesis increased Ketolysis decreased
? Leads to Ketosis-Ketonemia and Ketonuria
Prolonged Starvation Leads to
? Ketosis (Ketonemia and Ketonuria)
? High levels of Ketone Bodies in blood and
urine
? Ketoacidosis
? Severe Ketosis
? Lowered blood pH
? Nausea ,Acetone breath
? Coma, Death
?3 days starvation
[Ketone Bodies]=3mM
?3 weeks starvation
[Ketone Bodies]=7mM
Cure For Ketosis
? Ketosis Cured by infusion of
Glucose.
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
Starvation Alters BMR
? BMR is first affected in starvation
? In starvation metabolism decreases
? During starvation BMR is Decreased
Biochemical Adaptations
By Organs
During Starvation Phase
The Fasting State:
Glucagon stimulates glucose
production and release in liver.
Also mobilizes the fatty acids
(sparing Glucose for the Brain)
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
Metabolic Response to Starvation is
Characterized
? Switch from carbohydrate metabolism to fat
metabolism,
? Context of a hypometabolic state, with minimized
catabolism
? Initial y, stores of carbohydrate precursors (eg.
glycogen) are depleted via Glycogenolysis within 24 hrs.
? In first 24-48 hours there is increased gluconeogenesis
from amino acids and glycerol.
? Subsequently, Ketogenesis takes over, and much of the
body metabolic needs are met by ketone bodies and
free fatty acids.
? This is the consequence of decreasing insulin levels,
and relatively increased influence from catecholamines
and cortisol.
? Over prolonged starvation, protein catabolism begins,
resulting in degradation of structural y important
proteins, and organ system dysfunction.
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.
Consequences Of Starvation
? Severe Nutrient deficiency
? Affects vitality and Damages Important
Internal Organs /System
? Anaemia (Iron and Protein deficiency)
? Decreased BMR
? Fatigue, Weakness
? Low Immunity
? Increases Sleep
? Night blindness (Vitamin A deficiency)
? Scurvy (Vitamin C deficiency)
? Irregular Menses
? Constipation
? Bone Loss
? Dehydration
? Water Electrolyte Imbalance
? High Blood Pressure
? Brain Defects
? Coma and Death (Life Ends)
Questions
? Explain the different stages of
starvation & biochemical alterations
in the body during these stages.
OR
? Biochemical alterations/adaptations
during starvation.
? Describe role of following
organs during various stages of
starvation
? Liver
? Brain
? Muscles
? Adipose tissues
THANK YOU
Biochemistry
This post was last modified on 05 April 2022