Body Fluids, Type and Regulation Complete Notes PPT/PDF

Body Fluids, Type and Regulation 

Body
Fluids

Body Fluids

• Total
  amount of fluid in the human body is approximately 70% of body weight 
• Body fluid
  has been divided into two compartments –

§  Intracellular fluid 
(ICF)

Ø  Inside the cells

Ø  55% of total body water

§  Extracellular fluid

Ø  Outside the cells

Ø  45% of total body water

Composition of body fluids

•  Organic substances

§  Glucose

§  Amino
acids

§  Fatty
acids

§  Hormones

§  Enzymes

•     Inorganic substances

§  Sodium

§  Potassium

§  Calcium

§  Magnesium

§  Chloride

§  Phophate

§  Sulphate

Extracellular fluid 

·        
Interstitial fluid

§  Present between the cells

§  Approximately 80% of ECF

·        
Plasma

§  Present in blood

§  Approximately 20% of ECF

·        
Also includes

§  Lymph                              

§  synovial fluid

§  cerebrospinal fluid

§  pleural, pericardial and peritoneal fluids

1)
Extracellular fluids:

a) Interstitial Fluid: also known as
intercellular fluid and tissue fluid is fluid between the cells of
multi-cellular organisms which delivers materials to the cells, intercellular
communication, and removal of metabolic waste.

·        
It represents the largest portion of
the ECF compartment.

·        
Interstitial fluid consists of
a water solvent containing amino acids, sugars, fatty acids, coenzymes, hormones,
neurotransmitters, salts, as well as waste products from the cells.

• This
  fluid presents as gel-like extracellular matrix.
• The
  plasma and the interstitial fluid integrate through pores in the
  blood capillaries which allow water and most dissolved substances except
  protein to diffuse.
• Oxygen,
  nutrients, and regulatory molecules travelling in the blood must first
  pass into the interstitial fluid before reaching the body cells. Waste
  products and hormone secretions from the cells must first pass into the
  interstitial fluid before reaching the blood plasma.
• The
  exchange of material across the capillaries occurs at high rate by diffusion
  in both directions.
• The
  composition of tissue fluid depends upon the exchanges between the cells
  in the biological tissue and the blood. This means that tissue fluid has a
  different composition in different tissues and in different areas of the
  body.
• The
  composition of tissue fluid depends upon the exchanges between the cells
  in the biological tissue and the blood. This means that
  tissue fluid has a different composition in different tissues and in
  different areas of the body
• Acting
  as a media for intercellular communication.

Barriers separate ICF, interstitial fluid and
plasma

·        
Plasma
membrane

§  Separates
ICF from surrounding interstitial fluid

·        
Blood
vessel wall

§  Separate
interstitial fluid from plasma

2) Blood plasma:

·        
It is the fluid portion of the blood.

·        
The blood transports oxygen from the
lungs to the body cells and carbon dioxide from the body cells to the lungs.

·        
Blood also transports nutrients
derived from food in the intestine to the body cells, other nutrients between
organs.

3) Lymph

• Clear and colorless fluid
• 96% water and 4% solids
• Solids –

§  Proteins

Ø  2-6% of solids

Ø  albumin, globulin, fibrinogen, prothrombin, clotting
factors, antibodies, enzymes

§  Lipids

Ø  5-15%

Ø  Chylomicrons

Ø  Lipoproteins

§  Carbohydrates

Ø  Glucose mainly

§  NPN
(Non protein Nitrogen)

Ø  Urea and creatinine

§  Electrolytes

Ø  Sodium, calcium, potassium, chloride, bicarbonates

Functions of Lymph

• Return
  protein from tissue spaces into blood
• Removal of
  bacteria, toxins and other foreign bodies from tissues
• Maintain
  structural and functional integrity of tissue
• Route for
  intestinal fat absorption
• Transport
  lymphocytes

2)
Intracellular Fluid:

The cytosol or intracellular fluid is the
liquid found inside the cells.

Physiological Function: The
cytosol has no single function and instead it is the site of multiple
cell processes including metabolic processes (such as glycolysis, gluconeogenesis,
PPP). It is also involved in signal transduction from the cell membrane
to sites within the cell.

The body fluid composition of tissue varies by

1.       Tissue type:
   lean tissues have higher fluid content than fat tissues.
2.       Gender: males have
   more lean tissue and therefore more body fluid.
3.       Age: lean tissue
   is lost with age and body fluid is lost with it.

Body fluid composition:

1.       Water
2.       Dissolved solutes

a)     
Organic substances – protein, glucose

b)     
Inorganic substances – electrolytes e.g Na⁺, K⁺

Since
water passes freely across cell membrane, the volume of the various fluid
compartments are determined by unique solutes that are confined to each space.

For
the total extracellular fluid compartment it is sodium and for the
intracellular space, it is potassium.

Electrolytes of the body fluids:

•          Electrolytes
  are salts and minerals that can conduct electrical impulses in the body.
•         Common
  human electrolytes are sodium, chloride, potassium, calcium, and bicarbonate.
•         Electrolytes
  in body fluids are charged,
•         It can be:
•      Cation – positively charged electrolyte, e.g .Na⁺, k⁺, Ca⁺²
•      Anion – negatively charged electrolyte, e.g, Cl^– , HCO₃^–  po₄^-3
•      The chief extracellular
  cation is Na⁺
•      The chief intracellular
  cations are k⁺

§  Cl^– is the predominant anion outside
cells whereas phosphates constitute the bulk of intracellular anions.

Electrolytes:

·        
Control the
fluid balance of the body

·        
Important

a)     
In muscle
contraction 

b)     
In energy
generation – and almost every major biochemical reaction in the body.

Movement of body fluids:

Membrane transport
processes:

1) Passive transport

•         It is the
  movement of substances across a membrane from higher to lower concentration
  (down a concentration gradient)
•         It does not
  require metabolic energy.

Simple diffusion –

•          It is the
  movement of substances from a region of high concentration to a region of low
  concentration.
•          Generally,
  simple diffusion of water, gases, and other small uncharged molecules across
  plasma membranes can occur in the absence of transport proteins.

Facilitated diffusion –

•          It is a
  transport of substances across a biological membrane
•          From an
  area of higher concentration to an area of lower concentration by a carrier
  proteins.

2) Active transport:

•         It is the
  movement of substances across a membrane against gradient (from low
  concentration to high concentration).
•          Active
  transport requires energy and involves specific carrier proteins.

Movement of fluids due to

1) Hydrostatic pressure

2) Osmotic pressure

1) Hydrostatic pressure:

It is physiological
processes that regulate fluids intake & output as well as movement of water
& substances dissolved in it between the body compartments          

 2) Osmotic pressure:

The pressure exerted by the
flow of water through a semi-permeable membrane separating two solutions with
different concentration of solute.

Osmosis:

It is diffusion of a solvent
(usually water molecules) through a semi-permeable membrane from an area of low
solute concentration to an area of high solute concentration.

Osmotic pressure:

• It is pressure which forces
  the water to move from where there is little dissolved solute to where there is
  lots dissolved solutes.
•  It is
  determined by the number of particles per unit volume of fluids
• The amount
  of osmotic pressure exereted by a solute is proportional to the number of
  molecules or ions.
• Osmoles is the unit used to express the concentration in
  term of numbers of particles.

Regulation
of body fluids and electrolytes

·        
Fluid
intake and output are balanced.

Water Balance:

Water balance exists when
water intake equals water output.

Water Intake:

•          The volume
  of water gained each day varies from one individual to the next.
•         About 60%
  of daily water is gained from drinking, 
•          Another 30%
  comes from moist foods, and 10% from the water of metabolism

Regulation of Water Intake:

•          The thirst
  mechanism is the primary regulator of water intake.
•         The thirst
  mechanism derives from the osmotic pressure of extracellular fluids and a
  thirst center in the hypothalamus.
•         Once water
  is taken in, the resulting distention of the stomach will inhibit the thirst
  mechanism.

Water Output:

•          Water is
  lost in urine, feces, perspiration, evaporation from skin (insensible perspiration), and from the
  lungs during
  breathing.
•          The route
  of water loss depends on temperature, relative humidity, and physical exercise.

Regulation of Water Output:

•          The distal convoluted
  tubules and collecting ducts of the nephrons regulate water output.
•          Antidiuretic hormone from the posterior pituitary causes a
  reduction in the amount of water lost in the urine.
•          When
  drinking adequate water, the ADH mechanism is inhibited, and more water is
  expelled in urine.

Disorders of water balance:

1.          Dehydration: water loss exceeds water intake
2.          Hypotonic hydration: ECF is diluted (there is increase in water,
   causing ECF sodium levels to lower (hyponatremia), increase in osmosis occurs
   and tissue cells swell (oedema).

Electrolytes

Electrolytes, charged
ions capable of conducting electricity, are present in all body fluids and
fluid compartments. Just as maintaining the fluid balance is vital to a normal
body function, so is maintaining electrolyte balance.

Although the concentration
of specific electrolytes differ between fluid compartments, a
balance of cations (positively charged ions) and anions (negatively charged
ions) always exists.

Electrolytes are important
for

•          Maintaining
  fluid balance.
•          Contributing
  to acid–base regulation.
•          Facilitating
  enzyme reactions.
•          Transmitting
  neuromuscular reactions.

Electrolyte Balance:

An electrolyte balance
exists when the quantities of electrolytes gained equals the amount lost.

Regulation of Electrolyte Intake:

• A person
  ordinarily obtains sufficient electrolytes from food eaten.
•  A salt
  craving may indicate an electrolyte deficiency.

Electrolyte Output:

• Losses of electrolytes occur
  through sweating, in the feces, and in urine.

Body Fluids, Type and Regulation Complete Notes PDF