BLOOD (CH.21) Flashcards
1
Q
Blood
A
- The temperature of blood is about 1°C higher than measured body temperature
- Blood is about four times more viscous than water, meaning that it is thicker
- Blood is a type of fluid connective tissue because it contains cells, a liquid ground substance (called plasma), and dissolved proteins.
2
Q
Components of Blood
A
- Erythrocytes: sometimes called_ red blood cells,_ form the lower layer of the centrifuged blood. They typically average about 44% of a “blood sample.”
- Buffy Coat: makes up the middle layer. This thin, slightly gray-white layer is composed of cells called** leukocytes** (or white blood cells) and cell fragments called platelets. The buffy coat forms less than 1% of a blood sample.
- Plasma: is a straw-colored liquid that lies above the buffy coat in the centrifuge tube; it generally makes up about 55% of blood.
3
Q
Components of Blood
A
- Formed Elements: erythrocytes and the components of the buffy coat
- It is best not to refer to all of these structures as “cells” because platelets are merely fragments broken off from a larger cell.
- The Formed Elements, together with the liquid plasma, compose whole blood (the substance we most commonly refer to simply as “blood”).
4
Q
Formed Elements in the Blood
A
- _ Erythrocytes:_ make up more than 99% of formed elements. primary function is to transport respiratory gases in the blood.
- Leukocytes: make up less than 0.01% of formed elements. leukocytes contribute to mounting an immune response and defending the body against pathogens.
Platelets: make up less than 1% of formed elements and help with blood clotting.
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5
Q
_ Hematocrit_
A
- The percentage of erythrocytes in the blood
- Adult males tend to have a hematocrit ranging between 42% and 56%
- Females’ hematocrits range from 38% to 46%
- Altitude can affect the hematocrit. -Thin air & less oxygen -body compensates by making more erythrocytes; more erythrocytes in the blood can carry more oxygen to the tissues.
6
Q
Erythrocytes
A
- commonly referred to as red blood cells, or RBCs,
- mature erythrocytes lack nuclei and organelles
- Function: transport oxygen and carbon dioxide to and from the tissues and the lungs
7
Q
Hemoglobin in Erythrocytes
A
- Every erythrocyte is filled with approximately 280 million molecules of a red-pigmented protein called _hemoglobin_
- Hemoglobin transports oxygen and carbon dioxide, and is responsible for the characteristic bright red color of arterial blood.
- **Globins: 4 **polypeptide chains found in hemoglobin molecule - -2 alpha (α) chains -2 beta (β) chains
8
Q
Hemoglobin
A
- These 4 globin chains each contain a nonprotein (or heme) group that is in the shape of a ring, with an iron ion (Fe2+) in its center.
- Each hemoglobin molecule can bind a combination of 4 oxygen/carbon doixide molecules
9
Q
Hemoglobin in Erythrocytes
A
- When blood is high in oxygen, it is termed oxygenated.
- when some oxygen is lost and carbon dioxide is gained during respiratory gas exchange, blood is called deoxygenated.
- Deoxygenated blood has a deep red color that is perceived as blue when observed through the skin and the subcutaneous layer.
10
Q
** Leukocytes**
A
- Leukocytes **contain a nucleus and cellular organelles **Leukocytes are “true cells”
- Leukocytes help initiate an immune response and defend the body against pathogens
- leukocytes are about 1.5 to 3 times larger than erythrocytes
- Leukocytes are motile and remarkably flexible.
- . Leukocytes enter the tissue by a process called diapedesis
- **Chemotaxis: **is a process whereby leukocytes are attracted to the site of infection by molecules released by damaged cells, dead cells, or invading pathogens
11
Q
Classification of Leukocytes
A
- five types of leukocytes are divided into two classes -**-granulocytes & Agranulocytes **based upon the presence or absence of visible organelles termed granules
12
Q
** Leukocytes**
(Granulocytes)
Neutrophils(50–70% )
Eosinophils(1–4%)
Basophils(0.5–1%)
A
- Neutrophils: The most numerous leukocyte in the blood is the **Neutrophil. **about 50–70% of the total number of leukocytes.
- They phagocytize infectious pathogens, especially bacteria, releasing Lysozyme
- Neutrophils are produced to target the bacteria
- Eosinophils: have reddish or pink-orange granules in their cytoplasm
- eosinophils constitute about 1–4% of the total number of leukocytes
- Fight parasitic infection and allergens
- Basophils: 1.5 times larger than erythrocytes.
- least numerous of the granulocytes,
- constituting about 0.5–1% of the total number of leukocytes
- primary components of basophil granules are histamine and heparin, which are released during anti-inflammatory or allergic reactions
- The release of heparin from basophils inhibits blood clotting (anticoagulation).
- When histamine is released from these granules, it causes an increase in the diameter of blood vessels (vasodilation)
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13
Q
Leukocytes
Agranulocytes
Lymphocytes(20–40%)
B-lymphocytes (B-cells)
T-lymphocytes (T-cells)
Natural killer cells (NK cells)
Monocytes( 2–8%)
A
- **Lymphocytes: **constitute about 20–40% of the total number of leukocytes(wbc)
- most lymphocytes reside in lymphatic organs and structures.
- most important cells of the immune system
- Located in CT, nOT in blood stream, most enmeshed in Lymphoid Connective tissues.
- Play important role in immunity
There are three categories of lymphocytes:
- **T-lymphocytes (T-cells): **manage and direct an immune response; some directly attack _foreign cells and virus-infected cells. _
- B-lymphocytes (B-cells): are stimulated to become plasma cells and produce antibodies.
- ** Natural killer cells (NK cells):** attack abnormal and infected tissue cells.
** Monocytes:**
- constitute about 2–8% of all leukocytes
- **structure: **up to three times the diameter of an erythrocyte
- nucleus of a monocyte is kidney-shaped or C-shaped.
- After approximately 3 days in circulation, monocytes exit blood vessels and take up residence in the tissues, where they change into large phagocytic cells called macrophages
- **Function: **Macrophages phagocytize bacteria, cell fragments, dead cells, and debris
14
Q
Platelets
A
- are irregular, membrane-enclosed cellular fragments that are about 2 micrometers in diameter
- platelets are about one-fourth the size of an erythrocyte
- Platelets are sometimes called thrombocytes
- Platelets are continually produced in the red bone marrow by cells called megakaryocytes
- megakaryocytes are about 15x larger than erythrocytes
- Platelets are involved in blood clotting
15
Q
Platelets
clotting
A
- Severe trauma to a blood vessel causes the blood to coagulate, or clot
- ** components in the plasma produce a web of fibrin that traps erythrocytes and platelets and halts blood flow.**
- ** clot: the mass consisting of fibrin strands, platelets and blood cells that seals a tear**
- clot: contract in a muscle-like way,pulling the edges of the tear together
- Thrumbus: a clot that developes and presists in an intact damaged blood vessel
