Topic 6: Physiological role of the blood, definitions and changes in blood volumes Flashcards Preview

Essay 1-16, 1st midterm > Topic 6: Physiological role of the blood, definitions and changes in blood volumes > Flashcards

Flashcards in Topic 6: Physiological role of the blood, definitions and changes in blood volumes Deck (8)
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1
Q

What should be mentioned in this topic?

A
  • Physiological Role of Blood
  • Hematocrit
  • Sedimentation Rate
  • pH of the Blood
  • Determination of Blood Volume
  • Changes of Blood Volume
  • Factors affecting Blood Volume
2
Q

Physiological Role of Blood:

A

The primary function of blood is transportation. It is the main transport medium of:
- Gases
- Nutrients
- Metabolites
- Information
- Heat
Blood is an important buffer and takes part in defence and reacts after vessel injuries. It is also important in homeostasis.
As a buffer there are two types found in the blood:
- Bicarbonate – 53%
- Non bicarbonate – 47% Homeostasis
- Isovolemia, Isotonia, Isoionia, Isohydria

Blood is a liquid connective tissue consisting of 90% water. It consists of blood plasma and suspended cellular elements. It can be separated into a liquid phase and corpuscular elements.
Plasma contains fibrinogen – Collected from anticoagulated blood Serum does not contain fibrinogen – Collected from normal blood

3
Q

Hematocrit

A

It shows the proportion of corpuscular elements relative to the whole volume. It is an important diagnostic parameter.
Average value is around 40% or 0.4.

4
Q

Sedimentation Rate

A

The determination of the sedimentation rate is done using anticoagulated blood put in a standard size tube. The thickness of the plasma layer formed on the top of the tube is measured in certain time periods.

5
Q

pH of the Blood

A
  • Blood pH is 7.35-7.45
  • Extremely stable
  • Can withstand fluctuations for short periods 7.1-7.6
  • pH arterial > pH venous due to transport of CO2
6
Q

Determination of Blood Volume:

A

Ideal substance for measurement should not cross capillary wall. This substance does not exist, hence extrapolation is required.
To measure plasma space, Evans Blue or 125-I/131-I are used
To measure blood cell volume, labelled red blood cells are used

7
Q

Calculation of Blood Volume:

A

Calculation of Blood Volume (V) on the basis of plasma volume (Vp) or blood cell volume (Vrbc) In case of Ht value being known:

  • V=Vp/(1-0.9xHt)
  • V=Vrbc/0.9xHt
8
Q

Changes of blood volume:

A
Normocythaemic normovolaemia
Polycythaemic normovolaemia
Olygocythaemic normovolaemia
Normocythaemic hypovolaemia (Oligaemia)
Polycythaemic hypovolaemia
Olygocythaemic hypovolaemia
Normocythaemic hypervolaemia
Polycythaemic hypervolaemia
Olygocythaemic hypervolaemia