Topic 6 - Physiological role of the blood, definitions and changes in blood volumes

Question 1

Words to include in physological role of blood

Answer 1

• Transportation
  
  • Blood gases
  • Nutrients
  • Metabolites
  • Information
  • Heat
• Buffer
  
  • Bicarbonate
  • Non bicarbonate
• Defense
• Reacts after vessel injuries
• Homeostasis
  
  • Isovolemia (volume)
  • Isotonia (osmotic pressure)
  • Isoionia (ion-composition)
  • Isohydria (pH)
• Haemostasis
  
  • Coagulation
• Liquid connective tissue
• Cosists of:
  
  • Water (90%)
  • Blood plasma
  • Suspended cellular element
    
    • Corpscular elements
      
      • Red blood cells
      • White blood cells
      • Thrombocytes
• Liquid phase
• Corpuscular elements
• Total fresh blood
  
  • Anti-coagulation, centrifugation
    
    • Plasma
      
      • Fibrinogen
    • Cellular elements
  • Anti-coagulation ø, resting period
    
    • Serum
      
      • ø fibrinogen
    • Blood clot
      
      • Fibrin-web
• Hematocrit
  
  • Proportion of corpuscular elements (40%)
• Sedimentation of blood cells
  
  • Hematocrit
    
    • Velocity of sedimentation of corpusclar elements
  • Anticoagulated blood
• pH of blood
  
  • 7.35-7.45
    
    • 7.1
    • 7.6
  • pH_venous < pH_arterial
    
    • CO₂ transport
  • Acidosis
  • Alkalosis

Question 2

Words to include in changes in blood volumes

Answer 2

Blood volume

• Calculation
  
  • Plasma volume
  • Blood cell volume

Changes of blood volume

• Normovolemia
  
  • Normocythaemic norvolaemia
    
    • Healthy
  • Polycythaemia norvolaemia
    
    • Haemoconcentration
    • Viscosity ↑
    • Turbulence
  • Olygoythaemic norvolaemia
    
    • Haemodilution
• Hypovolemia
  
  • Normocythaemic hypovolaemia
    
    • Oligaemia
    • Blood loss
  • Polycythaemic hypovolaemia
    
    • Anhydremia
    • Haemoconcentration
  • Olygocythaemic hypovolaemia
• Hypervolaemia
  
  • Normocythaemic hypervolaemia
    
    • Plethora
    • Excess transfusion
  • Polycythamic hypervolaemia
  • Olygocythaemic hypervolaemia
    
    • Hydraemia
    • Infusion

Factors affecting blood volume

• Amount of body fat
• Position of the body
• Muscle work
• Climate
• Nutrition
• Lack of oxygen
• Sympathetic activity
• Pregnancy
• Blood loss
• Change in total water supply
• Age

Question 3

Physological role of blood

List the different functions of blood

Answer 3

1. Transportation
   
   • ​​Blood gases
   • Nutrients
   • Metabolites
   • Information
   • Heat
2. Buffer
   
   • ​Blood is an important buffer and takes part in defense and reacts after vessel injuries
   • Two types of buffer are found in the blood:
     
     • Bicarbonate
     • Non-bicarbonate
3. Homeostasis
   
   • ​​Isovolemia: Constant volume
   • Isotonia: Constant osmotic pressure
   • Isoionia: Constant ion-composition
   • Isohydria: Constant pH
4. Defense machanism
5. Haemostasis - coagulation
   
   • ​Reaction after vessel injuries

Question 4

Composition of blood

Answer 4

• Blood is a liquic connective tissue
• Consists of:
  
  • Water (90%)
  • Blood plasma (liqid phase)
  • Suspended cellular elements
    
    • Corpuscular elements
      
      • Red blood cells
      • White blood cells
      • Thrombocytes
• Blood plasma and suspended cellular elements can be separated into a liquid phase and corpscular elements
  
  • ​Done by centrifugation or setteling

Question 5

Hematocrit

Answer 5

• Hematocrit shows the proportion of corpuscular elements to the whole volume
• It is an important diagnostic parameter
• Average value: 40% or 0.4
  
  • Highest value: dog (0.46)
  • Lowest value: goat, sheep, hen (0.32)

Question 6

Sedimentation of blood cells

Answer 6

• The hematocrit shows us the velocity of the sedimentation of corpuscular elements
• The determination of the sedimentation rate is done using anticoagulated blood
• Blood sedeminetation rate:
  
  • Horse: 60-70 mm/hour (highest)
  • Cattle: 0-2 mm/hour (lowest)

Question 7

pH of the blood

Answer 7

• Blood pH is 7.35-7.45
• For a short period of time:
  
  • pH 7.1 (lowest value)
  • pH 7.6 (highest value)
• pH_venous < pH_arterial
  
  • ​Due to CO₂ transport
• Acidosis
• Alkalosis

Question 8

Changes in blood volumes

How to calculate blood volume?

Answer 8

• Calculation of blood volume on the basis of:
  
  • Plasma volume
  • Blood cell volume
• Blood volume: 80 ml/bwt
• Plasma volume: 45 ml/bwt
• Blood cell volume: 35 ml/bwt

Question 9

Changes in blood volumes

List all of the different types of blood volume

Answer 9

Normovolaeemia:

1. Normocythaemic norvolaemia
   
   • Healthy stage
2. Polycythaemia norvolaemia
   
   • Haemoconcentration
   • Viscosity increases
   • Increased load on the heart (turbulence)
3. Olygoythaemic norvolaemia
   
   • Haemodilution
   • Blood gets diluted with concurrent normal volume

Hypovolaemia:

1. Normocythaemic hypovolaemia
   
   • Blood cells and plasma loss together
2. Polycythaemic hypovolaemia
   
   • Anhydraemia: lack of water, thirst
3. Olygocythaemic hypovolaemia

Hypervolaemia:

1. Normocythaemic hypervolaemia
   
   • Plethora
   • Excess transfusion
   • Permanent, exhausing physical work
2. Polycythamic hypervolaemia
3. Olygocythaemic hypervolaemia
   
   • Hydraemia
   • Intake of excess water
   • Infusion (followed by haemodilution)

Question 10

Changes in blood volumes

Factors affecting blood volume

Answer 10

• Amount of body fat
• Position of the body
• Muscle work
• Climate
• Nutrition
• Lack of Oxygen
• Sympathetic activity
• Pregnancy
• Blood Loss
• Change in total water supply
• Age