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Blood – Part 1. Chapter 10. Blood. Is the “river of life” that surges within us. transports everything that must be carried in the body : nutrients , wastes ,& body heat through blood vessels. Is the only fluid tissue. Composition of Blood.

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Blood part 1

Blood – Part 1

Chapter 10


Blood
Blood

  • Is the “river of life” that surges within us.

  • transports everything that must be carried in the body : nutrients, wastes,& body heat

  • through blood vessels.

  • Is the only fluid tissue.


Composition of blood
Composition of Blood

  • Blood contains both solid and liquid components.

    • Formed Elements – Cellular portion of blood.

      • Contains living blood cells.

    • Plasma – The fluid portion of the blood.

      • Nonliving fluid matrix.


Composition of blood1
Composition of Blood

  • If blood is spun in a centrifuge, 3 layers are formed:

    • Bottom Layer- The heavier formed elements are packed down by centrifugal force.

      • Most of the reddish mass at the bottom is erythrocytes (RBC that function in O2 transport).


Composition of blood2
Composition of Blood

2. Top Layer - The lighter plasma rises to the top.


Composition of blood3
Composition of Blood

3. Buffy Coat - Thin, whitish layer between the formed elements layer and the plasma layer.

  • Contains:

  • Leukocytes-WBC that act in various ways to protect the body

  • Platelets-cell fragments that function in blood clotting.


Percent composition of blood
Percent Composition of Blood

  • Percent of the total volume of blood:

    1. Erythrocytes = 45%

    • Percentage known as hematocrit

      2. WBC & Platelets = >1%

      3. Plasma = 55%


Physical characteristics of blood
Physical Characteristics of Blood

1.Texture: Sticky opaque fluid; Heavier than water & about 5 times thicker (viscous) than water

2.Taste: Metallic & salty

3.Color: Varies from scarlet (oxygen-rich) to dull red (oxygen-poor)


Physical characteristics of blood1
Physical Characteristics of Blood

  • pH: Slightly alkaline (pH between 7.35 and 7.45)

  • Temperature – Always slightly higher than body temperature (100.4°F)

  • Body Weight and Volume: Accounts for approximately 8% of body weight; Volume in healthy males is about 5-6 L


Plasma
Plasma

  • The liquid part of the blood.

    • Is ~90% water.

    • Over 100 different substances are dissolved in this straw-colored fluid.

      • Examples include: nutrients, salts, respiratory gases, hormones, plasma proteins, and various wastes

    • Functions:

      • Transports various substances around the body.

      • Helps to distribute body heat evenly throughout the body.


Plasma proteins
Plasma Proteins

  • The most abundant solutes in plasma.

    • Serve a variety of functions:

      • Albumin – Contributes to the osmotic pressure of blood, which acts to keep water in the bloodstream.

      • Clotting Proteins help stop blood loss when a blood vessel is injured.

      • Antibodies help protect the body from pathogens.

      • Plasma proteins are NOT taken up by the cells to be used as food fuels or metabolic nutrients.


Composition of plasma
Composition of Plasma

  • varies continuously as cells remove or add substances to the blood.

    • kept relatively constant by various homeostatic mechanisms.

      • When blood proteins drop to undesirable levels - liveris stimulated to make more proteins.

      • When the blood starts to become too acidic or too basic- the respiratory system and the kidneys are called into action to restore it


Formed elements
Formed Elements

  • Make up about 45% of whole blood.

  • Contains erythrocytes or red blood cells (RBCs).

    • Function: To ferry O2 to all of the cells of the body.

    • Contain no organelles.

    • Are sacs of hemoglobin (Hb).

    • Hemoglobin- An iron-containing protein that transports the bulk of the oxygen that is carried by the blood.


Shape of erythrocytes
Shape of Erythrocytes

BICONCAVE DISCS

  • Flattened with depressed centers.

  • They look like doughnuts when viewed through a microscope.

  • small size & peculiar shape=a large surface area relative to their volume, making them ideally suited for gas exchange.


Number of erythrocytes rbcs
Number of Erythrocytes (RBCs)

  • RBCs outnumber WBCs by about 1000 to 1.

  • Are the major factor contributing to blood viscosity.

    • RBCs increase, blood viscosity increases.

    • RBCs decrease, the blood thins and flows more rapidly.


Hemoglobin
Hemoglobin

  • The more hemoglobin molecules the RBCs contain, the more O2 they will be able to carry.

    • Each hemoglobin molecule can bind 4 molecules of O2


Hemoglobin hb
Hemoglobin (Hb)

  • The most accurate way of measuring the oxygen-carrying capacity of the blood is to determine how much Hb it contains.

    • A single RBC contains ~250 million Hb molecules.

      • Each Hb molecule can bind 4 molecules of O2. Therefore, each of these tiny RBCs can carry about 1 billion O2 molecules!

  • The Hb content is slightly higher in men than women.


Anemia
Anemia

  • A decrease in the oxygen-carrying ability of the blood.

    • May be the result of:

      • Lower-than-normal number of RBCs

      • Abnormal or deficient hemoglobin content in the RBCs


Sickle cell anemia
Sickle Cell Anemia

  • Genetic defect that leads to abnormal Hb, which becomes sharp and sickle-shaped under conditions of increased O2 use by the body.

    • The deformed (crescent-shaped) RBCs rupture easily and dam up in small blood vessels.

      • These events interfere with oxygen delivery and cause severe pain.


Sickle cell anemia1
Sickle Cell Anemia

  • Occurs mostly in African Americans, who live in the malaria belt of Africa and among their descendants.

    • Individuals with the sickle-cell gene have a better chance of surviving where malaria is prevalent.

      • The same gene that causes sickle cell anemia, also makes RBCs infected by the malaria-causing parasite stick to the capillary walls and then lose potassium (an essential nutrient for the survival of the parasite).

      • The malaria causing parasite is prevented from multiplying.


Polycythemia
Polycythemia

  • An excessive or abnormal increase in the number of erythrocytes.

    • May result from:

      • Bone marrow cancer

      • Normal physiological response to living at high altitudes, where the air is thinner and less oxygen is available.

    • Major problem that results from high numbers of RBCs is increased blood viscosity.

      • Increased blood viscosity causes RBCs to flow sluggishly in the body and impairs circulation.


Leukocytes
Leukocytes

  • White blood cells (WBCs); crucial to the bodies defense against disease.

    • Far less numerous than RBCs

    • Account for >1% of total blood volume.

    • Form a protective, moveable army that helps defend the body against damage by bacteria, viruses, parasites, and tumor cells.


Wbcs special characteristics
WBCs: Special Characteristics

  • Are able to slip into and out of the blood vessels – a process called diapedesis.

    • The circulatory system is their means of transportation to areas of the body where their services are needed for inflammatory or immune responses.


Wbcs special characteristics1
WBCs: Special Characteristics

  • Can locate areas of tissue damage and infection in the body by responding to certain chemicals that diffuse from the damaged cells.

    • Called positive chemotaxis.


Positive chemotaxis
Positive Chemotaxis

  • Once they have “caught the scent,” the WBCs move through the tissue spaces by ameboid movement .

    • Ameboid Movement - Flowing cytoplasmic extensions that help them move.

  • By following the diffusion gradient, they pinpoint the areas of damage and rally round in large numbers to destroy foreign substances or dead cells.


Positive chemotaxis1
Positive Chemotaxis

AmeboidMovement - Flowing cytoplasmic extensions that help them move.

  • By following the diffusion gradient, they pinpoint the areas of damage and rally round in large numbers to destroy foreign substances or dead cells.


Number of wbcs
Number of WBCs

  • Whenever WBCs mobilize for action, the body speeds up their production.

    • twice the normal number may appear in the blood within a few hours.


Number of wbc s
Number of WBC’s

  • Leukocytosis – A total WBC count above 11,000 cells/mm3

    • indicates that a bacterial or viral infection is stewing in the body.


Number of wbc s1
Number of WBC’s

  • Leukopenia– Abnormally low WBC count.

    • Commonly caused by certain drugs, such as corticosteroids and anticancer agents.


Leukemia
Leukemia

  • “White blood”; Bone marrow becomes cancerous; Excessive production of abnormal WBCs.

    • The “newborn” WBCs are immature and incapable of carrying out their normal protective functions.

    • the body becomes easy prey of disease-causing bacteria and viruses.


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