Fleur sam. Ch 16
16.1 plasma and the cellular elements of blood
Blood is a connective tissue composed of cellular elements suspended in an
extensive fluid matrix called plasma.
Plasma makes up 1/4th of the ECF, the internal environment that bathes cells and
acts as buffer between cells and external environment.
Blood is the circulating portion of the extracellular compartment, responsible for
carrying material from 1 part of the body to another.
Blood is equal to about 7% of the total body weight.
1 kg of blood occupies a volume of 1 L (so 70 kg man, has 0.07 x 70= 4.9 kg blood
weight, = about 5 L of blood).
Of this volume, about 2 L is composed of blood cells, while the remaining 3 L is
composed of plasma, fluid portion of the blood.
Plasma is the fluid matrix of the blood, within which cellular elements are suspended.
- Water is the main component of plasma, accounting for about 92% of its weight.
- Proteins account for another 7%
- The remaining 1% is dissolved organic molecules (amino acids, glucose, lipids,
nitrogenous wastes), Ions (Na+, K+, Cl-, h+, Ca2+, HCO3-), trace elements and
vitamins, dissolved O2 and CO2.
Plasma has the same composition to interstitial
fluid, except it has plasma proteins.
Albumins are the most prevalent type of proteins
the plasma (making up about 60% of the total).
Albumins and 9 other proteins, including:
- Globulins
- the clotting protein fibrinogen
- the iron-transporting protein transferrin
those 3 make up more than 90% of all plasma
proteins.
Liver makes most plasma proteins and secretes them into the blood.
Some globulins, known as immunoglobulins or antibodies are synthesized and
secreted by specialized blood cells rather than by the liver.
Presence of proteins in the plasma makes the osmotic pressure of the blood higher
than that of the interstitial fluid.
This osmotic gradient tends to pull water from the interstitial fluid into the capillaries
and offset (=weegt op tegen) filtration out of the capillaries created by blood
pressure.
Plasma proteins participate in many functions:
- including blood clotting and defense against foreign invaders.
- They also act as carriers for steroid hormones, cholesterol, drugs and certain ions,
such as iron (Fe2+).
, - Finally, some plasma proteins act as hormones or as extracellular enzymes.
The 3 main cellular elements in blood are:
- red blood cells (RBC)/=erythrocytes. RBCs have lost their nuclei by the time they
enter the bloodstream. Play key role in transporting O2 from lungs to tissues, and
CO2 rom tissues to lungs.
- white blood cells (WBC)/=leukocytes. WBCs are the only fully functional cells in the
circulation. Play key role in body’s immune responses, defending the body against
foreign invaders, like parasites, bacteria and viruses. Most WBC’s circulate through
the body in the blood, but their work is usually carried out in the tissues rather than in
the circulatory system.
- Platelets/ = thrombocytes. Lack a nucleus.
Platelets have no nucleus and are cell fragments that have split off from a large
parent cell known as megakaryocytes. Platelets are instrumental in coagulation, the
process by which blood clots prevent blood loss in damaged vessels.
Blood contains of 5 types of mature white blood
cells:
1. Lymphocytes
2. Monocytes
3. Neutrophils
4. Eosinophils
5. Basophils
Monocytes that leave the circulation and enter
the tissues develop into macrophages. Tissue
basophils are called mast cells.
The types of WBC’s may be grouped according
to common morphological/functional
characteristics.
Neutrophils, monocytes and macrophages
are known as phagocytes, because they engulf
and ingest foreign particles like bacteria
(phagocytosis).
Lymphocytes are sometimes called immunocytes because they are responsible for
specific immune responses directed against invaders.
Basophils, eosinophils and neutrophils are called granulocytes, because they
contain cytoplasmic inclusions that give them a granular appearance.
16.1 plasma and the cellular elements of blood
Blood is a connective tissue composed of cellular elements suspended in an
extensive fluid matrix called plasma.
Plasma makes up 1/4th of the ECF, the internal environment that bathes cells and
acts as buffer between cells and external environment.
Blood is the circulating portion of the extracellular compartment, responsible for
carrying material from 1 part of the body to another.
Blood is equal to about 7% of the total body weight.
1 kg of blood occupies a volume of 1 L (so 70 kg man, has 0.07 x 70= 4.9 kg blood
weight, = about 5 L of blood).
Of this volume, about 2 L is composed of blood cells, while the remaining 3 L is
composed of plasma, fluid portion of the blood.
Plasma is the fluid matrix of the blood, within which cellular elements are suspended.
- Water is the main component of plasma, accounting for about 92% of its weight.
- Proteins account for another 7%
- The remaining 1% is dissolved organic molecules (amino acids, glucose, lipids,
nitrogenous wastes), Ions (Na+, K+, Cl-, h+, Ca2+, HCO3-), trace elements and
vitamins, dissolved O2 and CO2.
Plasma has the same composition to interstitial
fluid, except it has plasma proteins.
Albumins are the most prevalent type of proteins
the plasma (making up about 60% of the total).
Albumins and 9 other proteins, including:
- Globulins
- the clotting protein fibrinogen
- the iron-transporting protein transferrin
those 3 make up more than 90% of all plasma
proteins.
Liver makes most plasma proteins and secretes them into the blood.
Some globulins, known as immunoglobulins or antibodies are synthesized and
secreted by specialized blood cells rather than by the liver.
Presence of proteins in the plasma makes the osmotic pressure of the blood higher
than that of the interstitial fluid.
This osmotic gradient tends to pull water from the interstitial fluid into the capillaries
and offset (=weegt op tegen) filtration out of the capillaries created by blood
pressure.
Plasma proteins participate in many functions:
- including blood clotting and defense against foreign invaders.
- They also act as carriers for steroid hormones, cholesterol, drugs and certain ions,
such as iron (Fe2+).
, - Finally, some plasma proteins act as hormones or as extracellular enzymes.
The 3 main cellular elements in blood are:
- red blood cells (RBC)/=erythrocytes. RBCs have lost their nuclei by the time they
enter the bloodstream. Play key role in transporting O2 from lungs to tissues, and
CO2 rom tissues to lungs.
- white blood cells (WBC)/=leukocytes. WBCs are the only fully functional cells in the
circulation. Play key role in body’s immune responses, defending the body against
foreign invaders, like parasites, bacteria and viruses. Most WBC’s circulate through
the body in the blood, but their work is usually carried out in the tissues rather than in
the circulatory system.
- Platelets/ = thrombocytes. Lack a nucleus.
Platelets have no nucleus and are cell fragments that have split off from a large
parent cell known as megakaryocytes. Platelets are instrumental in coagulation, the
process by which blood clots prevent blood loss in damaged vessels.
Blood contains of 5 types of mature white blood
cells:
1. Lymphocytes
2. Monocytes
3. Neutrophils
4. Eosinophils
5. Basophils
Monocytes that leave the circulation and enter
the tissues develop into macrophages. Tissue
basophils are called mast cells.
The types of WBC’s may be grouped according
to common morphological/functional
characteristics.
Neutrophils, monocytes and macrophages
are known as phagocytes, because they engulf
and ingest foreign particles like bacteria
(phagocytosis).
Lymphocytes are sometimes called immunocytes because they are responsible for
specific immune responses directed against invaders.
Basophils, eosinophils and neutrophils are called granulocytes, because they
contain cytoplasmic inclusions that give them a granular appearance.
