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Flashcards in Outcome 5 Hemopoietic System Deck (33):

Functions of blood

-distribution (nutrients, oxygen and carbon dioxide, hormones, waste products)
-regulation (body temp and PH, and blood volume)
-defence (carries clotting agents, WBC's and antibodies)


Characteristics of blood

- a connective tissue composed of plasma and formed elements
-denser and 5X more viscous than water
-slightly alkaline (PH 7.35-7.45)
-blood volume about 5L in adults


Components of blood

-45% of blood volume is made up of formed elements and is known as the "hematocrit". It is mostly comprised by erythrocytes, but also contains leukocytes and platelets
-55% of blood volume is comprised of plasma, a sticky straw coloured fluid solution that is 91% water with over 100 different salutes mixed in


What two types of connective tissue make blood cells for the body?

1) myeloid tissue -> AKA red bone marrow. In adults it is found in the axial skeleton, shoulder and pelvic girdles. Forms all types of blood cells except lymphocytes, which is found in lymphoid tissue
2) lymphoid tissue -> found as white masses located chiefly in the lymph nodes, thymus and spleen. Makes lymphocytes


True or false: all formed elements of blood begin as stem cells known as hemocytoblasts and as they grow they differentiate into red or white blood cells



Erythrocytes production (erythropoiesis)

-regulated by erythropoietin (EPO) hormone levels in the blood
-EPO produced by the kidneys and liver
-when receptor cells in the kidneys detect that blood oxygen levels have fallen below normal, EPO production kicks in and rising the levels of EPO in the blood stream triggers erythropoiesis


Too low RBC count causes



Too high RBC count causes

Increased viscosity of the blood


Leukocyte and platelet production is stimulated by _____

Chemical messengers


Erythrocytes (red blood cells)

-no nucleus or standard cellular organelles
-biconcave donut shaped disks
-Essentially microscopic bags of hemoglobin (a protein that binds easily with oxygen)
-entire reason for existing is to transport oxygen and carbon dioxide to and from the lungs


Leukocytes (white blood cells)
- all involved in immunity

-only formed elements that are complete cells, with all the usual organelles
-lifespan varies from a few hours to months. Most live only a few days
-NEUTROPHILS-> most common; fight bacterial infection, immune response, phagocytosis
- EOSINOPHIL-> defence against parasites; also regulate allergic reactions
-BASOPHILS-> inflammation response and heparin secretion (anticoagulant)
-MONOCYTES-> macrophages with a big appetite for viruses and other chronic infections
-LYMPHOCYTES-> (B and T, natural killer cells) NB for immunity
-high WBC count may indicate: bacterial and viral infections, stress, TB, leukaemia and allergic reactions



-most common
-Fight bacterial infection
-immune response



-defence against parasites
-regulate allergic reactions



-inflammatory response
-heparin secretion (anticoagulant)



-macrophages with a big appetite for viruses and other chronic infections



-B and T
-natural killer cells
-NB for immunity



-cell fragments
-very important role in hemostasis
-will stop bleeding by forming a platelet plug and release chemicals


Hemostasis (blood clotting process)

- a sequence of reactions designed to stop bleeding and prevent blood loss
1) VASCULAR SPASM: damaged blood vessel begins to contract which helps stop the bleeding immediately and can help "buy time" until the other processed of hemostasis begin
2) PLATELET PLUG FORMATION: platelets arrive and begin sticking to the exposed surface of the vessel. Platelets also release several hormones and chemicals that trigger coagulation and the release of more platelets
3) BLOOD CLOTTING/COAGULATION: complex sequence of chemical reactions that reinforces the platelet plug and transforms the blood into a gel



-as blood circulates around the body, our blood plasma moves into the extra cellular spaces, bathes the cells in nutrients, removes their waste products, and returns to the blood stream
-during this some of the blood plasma remains behind in the extracellular spaces
-the "escaped" plasma is called interstitial fluid, it is collected daily by the lymphatic system, that transports the fluid back into the bloodstream to maintain the proper volume of blood in the circulatory system
-once this fluid is in the lymphatic system we call it "lymph"


Lymph nodes

-small filters found in clusters at certain locations along lymph vessels
-contain certain WBC's that filter out bacteria and damaged cells from the lymph, through phagocytosis


The 2 "pumping actions" that help the lymph move up through the body are

-skeletal muscles (contract with movement)
-respiration (change of internal pressure)


Lymphoid organs

-lymphatic system produces lymphocytes
-all lymphocytes originate from primitive stem cells in the red bone marrow
-not considered "mature" until they are "immune-competent" and "self-recognizing"
-B,T and NK


B lymphocytes

-mature in the red bone marrow


T lymphocytes

-mature in the thymus


Secondary lymphoid organs

-lymph nodes


Lymph nodes

-small organs that filter lymph before it is returned to the blood stream
-only feel the ones in the inguinal, axillary, and cervical regions
-contain macrophages that destroy foreign debris and microorganisms
-contain various types of lymphocytes that can be activated to produce specific defence responses
-sometimes lymph nodes become overwhelmed by their filtering duties and they become inflamed and swollen



-cleans the blood by removing aged and defective blood cells and platelets
-stores blood making components such as iron and hemoglobin
-stores platelets and produces erythrocytes until we are born


Specific (or adaptive) immunity

-specific immunity is built around the following two distinctive immune responses:
1) cell mediated immune response
2) humoral or antibody mediated immune response


Cell mediated immune response

-controlled primarily by the T lymphocytes which operate in two different ways
1) directly attack and kill cells that are infected with pathogens
2)they send out chemical alarm systems that activate other lymphocytes to launch a more widespread immune response


Humoral/ Antibody mediated immune response

-mainly revolves around B lymphocytes, which produce memory cells and plasma cells, once they have been activated by a chemical "call to arms" initiated by special "helper" T cells
-plasma cells produce antibodies, and the memory cells ensure that the body will recognize a certain antigen into the future (20 yrs or more) so that an immune response can be initiated more quickly and effectively



- abnormally low levels of RBCs in the blood
-most common cause is iron deficiency due to poor diet, or chronic blood loss from an ulcer etc



- cancer of leukocyte: overproduction of WBCs
-increased WBC count decreases production of other formed elements


Lymphoma: Hodgkin and non Hodgkin's lymphoma

-cancer of the lymphoid cells (B and T lymphocytes)
-90% of time it originates from lymph nodes
-once diagnosed the disease needs to be graded and staged
Graded: determines how aggressive or malignant a tumor is
Staged: determines how widespread the cancer is in the body
-symptoms mimic those of many common ailments such as the flu
-enlarged mediastinal nodes is most common radiographic finding