THE CARDIOVASCULAR SYSTEM: THE BLOOD
There are three major reasons why a cell becomes less capable of an independent
existence as it becomes more specialized? Identify these reasons.
1. It becomes less able to protect itself from temperature changes, toxic
chemicals, and changes in pH.
2. The cell loses the ability to seek and devour food.
3. If it is embedded within a tissue, as most body cells are, it cannot move
away from its own waste products.
What, then are cells in multicellular animals completely dependent upon for survival?
The internal environment, which must be always kept within physiological limits.
What is the internal environment?
The substance that bathes the differentiated cells, the interstitial fluid,
(intercellular or tissue fluid), carries out these vital processes for the cells and
constitutes the internal environment.
What is the relationship between interstitial fluid, plasma, and lymph?
When interstitial fluid enters blood vessels, it is called the blood plasma; when it
enters the lymphatic system it becomes lymph. Therefore, interstitial fluid, blood
plasma, and lymph are all but the same fluids; along with a few other fluids of the
body, they form the extracellular fluid (ECF).
What are the cardiovascular and lymphatic systems?
The blood, blood vessels, and heart form the cardiovascular system.
The lymph, lymphatic vessels, and structures and organs that contain lymphatic
tissue form the lymphatic system.
Since blood services all tissues of the body, it is an important medium for the transport
of disease-producing organisms throughout the body. Briefly, describe the role of the
lymphatic system in protecting the body from such spread of disease.
The lymphatic system receives interstitial fluid, which includes wastes and
possibly microorganisms, cancer cells, etc. and filters it through specialized
structures called lymph nodes. This in effect concentrates disease-producing
organisms, and provides defensive mechanisms for the body, prior to returning
the cleansed fluid to the blood for another pass through the body.
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, A. COMPONENTS OF THE BLOOD
Name the two main components of whole blood?
Whole blood consists of a cellular or cell-like portion called the formed
elements and a straw-colored liquid portion called the plasma.
1. BLOOD PLASMA
What are the two major components of plasma?
Approximately 55% of whole blood is plasma: 91.5% of this is
water.
The remaining 8.5% is solutes, primarily plasma proteins, as well
as a multitude of other solutes, all of which are maintained at
specific concentrations.
Describe the plasma proteins?
The plasma proteins, formed mainly by the liver, are divided into
three large groups:
albumins (54%)
globulins (38%)
fibrinogen (7%)
What is the hematocrit?
The formed elements can be separated from the plasma by placing
a sample of blood in a capillary tube and spinning if for a few
minutes in a centrifuge. RBCs, being denser than other blood
components, become packed into the bottom of the tube and on
average constitute about 45% of the total volume of blood. This
value is the hematocrit.
Laying atop the packed RBCs is the buffy coat. Making up less
than 1% of the total, this layer is composed of leukocytes and
platelets.
Above it all is the plasma, a pale yellow fluid that accounts for about
55% of the total.
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There are three major reasons why a cell becomes less capable of an independent
existence as it becomes more specialized? Identify these reasons.
1. It becomes less able to protect itself from temperature changes, toxic
chemicals, and changes in pH.
2. The cell loses the ability to seek and devour food.
3. If it is embedded within a tissue, as most body cells are, it cannot move
away from its own waste products.
What, then are cells in multicellular animals completely dependent upon for survival?
The internal environment, which must be always kept within physiological limits.
What is the internal environment?
The substance that bathes the differentiated cells, the interstitial fluid,
(intercellular or tissue fluid), carries out these vital processes for the cells and
constitutes the internal environment.
What is the relationship between interstitial fluid, plasma, and lymph?
When interstitial fluid enters blood vessels, it is called the blood plasma; when it
enters the lymphatic system it becomes lymph. Therefore, interstitial fluid, blood
plasma, and lymph are all but the same fluids; along with a few other fluids of the
body, they form the extracellular fluid (ECF).
What are the cardiovascular and lymphatic systems?
The blood, blood vessels, and heart form the cardiovascular system.
The lymph, lymphatic vessels, and structures and organs that contain lymphatic
tissue form the lymphatic system.
Since blood services all tissues of the body, it is an important medium for the transport
of disease-producing organisms throughout the body. Briefly, describe the role of the
lymphatic system in protecting the body from such spread of disease.
The lymphatic system receives interstitial fluid, which includes wastes and
possibly microorganisms, cancer cells, etc. and filters it through specialized
structures called lymph nodes. This in effect concentrates disease-producing
organisms, and provides defensive mechanisms for the body, prior to returning
the cleansed fluid to the blood for another pass through the body.
191
, A. COMPONENTS OF THE BLOOD
Name the two main components of whole blood?
Whole blood consists of a cellular or cell-like portion called the formed
elements and a straw-colored liquid portion called the plasma.
1. BLOOD PLASMA
What are the two major components of plasma?
Approximately 55% of whole blood is plasma: 91.5% of this is
water.
The remaining 8.5% is solutes, primarily plasma proteins, as well
as a multitude of other solutes, all of which are maintained at
specific concentrations.
Describe the plasma proteins?
The plasma proteins, formed mainly by the liver, are divided into
three large groups:
albumins (54%)
globulins (38%)
fibrinogen (7%)
What is the hematocrit?
The formed elements can be separated from the plasma by placing
a sample of blood in a capillary tube and spinning if for a few
minutes in a centrifuge. RBCs, being denser than other blood
components, become packed into the bottom of the tube and on
average constitute about 45% of the total volume of blood. This
value is the hematocrit.
Laying atop the packed RBCs is the buffy coat. Making up less
than 1% of the total, this layer is composed of leukocytes and
platelets.
Above it all is the plasma, a pale yellow fluid that accounts for about
55% of the total.
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