Lecture 9 - Fatty Acid Metabolism

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Advanced Physiology(part 3, Acid-base balance)
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By A. Riasi (PhD in Animal Nutrition
Physiology) Isfahan University of Technology (IUT)
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• Introduction

• Three aspects of the ECF and ICF that are
  crucial to the whole animal and to its individual
  cells
• The osmotic balance
• Total fluid volume of the body
• Acid base status

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• Introduction

• The term of acid-base balance refers to the
  precise regulation of free hydrogen ion (H) and
  hydronium ion (OH-) concentration in the body
  fluids.
• Acids are a special group of hydrogen-containing
  substances.
• A strong acid has a greater tendency to
  dissociated in solution than does a weak acid.

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• Acid-base balance in body fluids

?Adapted from Animal Physiology by Sherwood et
al. 2005
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• Acid-base balance in body fluids

• The normal pH of arterial and venous blood
• Acidosis exists whenever the blood pH falls
  below 7.35
• Alkalosis occurs when the blood pH is above 7.45
  
• Death can occur if arterial pH falls outside of
  the range of 6.8-8.0

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• Acid-base balance in body fluids

?Adapted from Animal Physiology by Sherwood et
al. 2005
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• Acid-base balance in body fluids

• Fluctuations in hydrogen ion concentration have
  profound effect on body chemistry.
• Even small changes in H have dramatic effect
  on proteins.
• The most prominent whole body consequences of
  fluctuations in H are changes in excitability
  of nerves and muscle cells.

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• Acid-base balance in body fluids

• Hydrogen ions are continually being added to
  body fluids
• Metabolic activities are main source for H in
  the body fluids
• Normally, H is continually being added to the
  body fluids by
• Carbonic acid formation
• Inorganic acid produced during the breakdown of
  nutrients
• Organic acid resulting from intermediary
  metabolism

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• Acid-base balance in body fluids

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• Acid-base balance in body fluids

• Sulfuric acid and phosphoric acid are produced
  in the body.
• Fatty acids and lactic acid that are produced
  during intermediary metabolism partially
  dissociate to yield free H.
• In certain disease additional acids may be
  produced.

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• Acid-base balance in body fluids

• Three line of defense against changes in H
• Chemical buffer systems
• Respiratory mechanisms of pH control
• Excretory mechanisms of pH control

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• pH Regulation Buffers

• There are four buffer system in the vertebrate
  body
• CO2-HCO3- buffer system
• The peptide and protein buffer system
• The hemoglobin buffer system
• The phosphate buffer system

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• pH Regulation Buffers

• The Co2-HCO3- buffer system in the ECF.

?Adapted from Animal Physiology by Sherwood et
al. 2005
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• pH Regulation Buffers

• The most plentiful buffers on the ICF are the
  cell proteins.
• The most important buffering amino acid is
  histidine.

• Hemoglobin (Hb) in erythrocytes buffers the H
  generated.
• The phosphate buffer system consists of an acid
  phosphate slat (NaH2PO4) and a basic phosphate
  salt (Na2HPO4).
• The phosphate system serve as an excellent
  urinary buffer.

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• pH Regulation Respiration

• The respiratory system plays an important role
  in acid-base balance through its ability to alter
  ventilation

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• pH Regulation Excretion

• The excretory organs are the third line of
  defense against changes in H in body fluids.
• In mammals, the kidneys are the most potent
  acid-base regulatory mechanism.
• The kidneys can remove of H from any source
• The kidneys can variably conserve or eliminate
  HCO3-

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• pH Regulation Excretion

• The kidneys control the pH of the body fluids by
  adjusting three interrelated factors
• H excretion
• H2CO3- excretion
• Ammonia secretion

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• pH Regulation Excretion

• Hydrogen ion excretion by the kidneys
• The kidneys eliminate H derived from sulfuric,
  phosphoric, lactic, and other acids.

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• pH Regulation Excretion

?Adapted from Animal Physiology by Sherwood et
al. 2005
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• pH Regulation Excretion

• The H secretary process begins in the tubular
  cells with CO2 that has come from three sources
• The CO2 diffused from plasma
• The CO2 diffused from the tubular fluid
• CO2 that has been metabolically produced within
  the tubular cells.

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• pH Regulation Excretion

• The kidneys adjust H excretion to compensate
  for changes in both carbonic and noncarbonic
  acids.
• The kidneys regulate plasma HCO3- by two
  mechanisms
• Variable reabsorption of the filtered HCO3- back
  to the plasma.
• Variable addition of new HCO3- to the plasma.

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• pH Regulation Excretion

?Adapted from Animal Physiology by Sherwood et
al. 2005
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• pH Regulation Excretion

?Adapted from Animal Physiology by Sherwood et
al. 2005