Chapter 19: Blood

Functions of Blood

* Transportation: O2 and CO2, nutrients, heat, and waste
* Regulation: homeostasis of body fluids, regulates pH, adjusts body temperature, blood osmotic pressure
* Protection: ability to clot, white blood cells carry on phagocytosis, blood proteins include antibodies

Plasma

straw-colored liquid, 91.5% water and 8.5% solutes (mostly proteins); makes up the largest percentage of total blood volume

Plasma Proteins

synthesized by hepatocytes (liver cells); includes albumins, globulins, and fibrinogen

Platelets

fragments of cell that don’t have a nucleus, release chemicals that promote blood clotting, originate from the cytoplasm of a megakaryocyte

White Blood Cells

protect the body from invading pathogens and other foreign substances

Red Blood Cells

transport oxygen to the body cells and transport CO2 to the lungs

Hematopoiesis

process of blood developing

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before birth: umbilical vesicle of an embryo → liver, spleen, thymus, and lymph nodes

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last 3 months of gestation and on: red bone marrow

Erythrocytes (Red Blood Cells)

biconcave discs, lack a nucleus, can’t reproduce or carry on extensive metabolic activities, contain hemoglobin (oxygen-carrying protein that makes it red); phagocytosed by macrophages in the spleen; broken down into globin, heme, and biliverdin

Function of Transferring and Ferritin

Transferrin: transporter of Fe3+ in the bloodstream, in bloodstream

Ferritin: protein that stores iron in cells, in liver

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act as protective “protein escorts” during transport and storage of iron ions

Neutrophil

* 60-70%
* phagocytic → eat and die creating pus
* small, purple granules and multi-lobed nucleus

Lymphocyte

* 20-25%
* long-term immunity
* minimal cytoplasm, nucleus takes up most space

Monocyte

* 3-8%
* blood macrophages (big eaters)
* large, kidney-bean nucleus

Eosinophil

* 2-4%
* parasite fighter, mildly phagocytic
* big, reddish-orange granules

Basophil

* 0-1%
* allergic reaction (release histamine)
* large, purple granules

Megakaryocyte

huge cells that splinter into 2000-3000 fragments

Platelet

each fragment of a megakaryocyte enclosed by a piece of plasma membrane

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break off from megakaryocytes in red bone marrow and enter the blood circulation

Pluripotent Stem Cell

give rise to all of the cell types that make up the body

Hemostasis

sequence of responses that stops bleeding

Vascular Spasm

contraction of circularly arranged smooth muscle in the walls of arteries or arterioles when they are damaged

Platelet Plug Formation

* Platelet Adhesion: platelets stick to exposed collagen
* Platelet Release Reaction: become activated → release chemicals that release more platelets
* Platelet Aggregation: platelets become sticky (due to ADP) → platelet plug forms

Clotting (Coagulation)

* formation of fibrin network
* blood clot: formation of insoluble protein fibers (fibrin) where the formed elements of blood are trapped
* extrinsic pathway: occurs rapidly, leaks into blood from cells outside blood vessels
* intrinsic pathway: occurs slower, activators are in direct contact within blood

Thrombin

positive feedback on clotting, converts fibrinogen into fibrin, 2 loops:

* accelerates the formation of prothrombinase → prothrombinase accelerates production of thrombin
* activates platelets → reinforces their aggregation and the release of platelet phospholipids

Fibrinogen

blood plasma protein formed in the liver, generates fibrin

Fibrin

forms the threads of the clot

Thrombus

blood clot

Embolus

blood clot that has moved from original location

Fibrinolytic System

dissolves small, inappropriate clots and clots at site of damage once damage is repaired

Plasminogen

inactive blood plasma enzyme that generates plasmin

Plasmin

digests fibrin, initiates destruction of blood clot

Landsteiner’s Rule

“You contain the antibody for the antigen you lack”

anti-Rh

an Rh- person will develop anti-Rh if and only if an Rh- person receives an Rh+ blood transfusion

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a second transfusion of Rh+ will cause agglutination and hemolysis of the RBCs

Hemolytic Disease of the Fetus

Rh- parent and Rh+ baby, anti-Rh can cross placenta and parent is exposed during birth, okay if untreated for first pregnancy but not for second

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prevention: RhoGam or RhIg → anti-Rh antibodies given at 28 weeks and delivery which prevents parent’s own anti-Rh creation

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treatment: intrauterine transfusion and exchange transfusion at birth

Reticulocyte

immature RBC that moves from the red bone marrow into the blood and matures into an RBC within 1-2 days

Erythropoiesis

production of RBCs in the red bone marrow

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proerythroblast → reticulocyte → RBC

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increased during: training at high altitudes, injection of erythropoietin, hemorrhage, anemia

Hormones that Stimulate Hematopoiesis

Erythropoietin (EPO): stimulates production of RBCs

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Thrombopoietin (TPO): stimulates the formation of platelets from megakaryocytes

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Cytokines: regulate development of blood cell types

Erythropoietin

Increases the number of circulating reticulocytes, oxygen carrying capacity, and bone marrow cell division