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What type of tissue is blood?

Connective Tissue

What is blood composed of?

Plasma and formed elements

What do the formed elements consist of?

Erythrocytes, leukocytes, and platelets

What % of blood volume is RBCs?

Males 47% +/- 5%
Females 42% +/- 5%

What is the pH of blood?

7.35-7.45

What % of body weight is blood?

Approx. 8%

Functions of blood:

-Distributes
-Regulates
-Protects

What does blood distribute?

-O2 and nutrients to cells
-Metabolic wastes to the lungs and kidneys for elimination
-Hormones from endocrine organs to target organs

What does blood regulate?

-Body temp (by absorbing and distributing heat)
-Normal pH (using buffers such as bicarbonate)
-Adequate fluid volume in the circulatory system (salts and blood proteins maintain osmotic pressure)

What does blood protect against?

-Blood loss (plasma proteins and platelets initiate clot formation)
-Infection (antibodies/complement proteins/WBCs defend against foreign invaders)

What does blood plasma consist of?

-Albumin
-Globulins
-Fibrinogen

Albumin

-Binds molecules
-Osmotic
-Buffer

Globulins

Antibody immune response

Fibrinogen

Forms fibrin in clotting

What % of plasma is water?

90%

What is blood plasma?

Nitrogenous by-products of metabolism (lactic acid/urea/creatinine)

What cells are the only complete cells?

WBCs

Which cells have no nuclei or organelles?

RBCs

What is a cell fragment

Platelets

What is the normal platelet count?

140,000-440,000

How long do formed elements survive in the bloodstream?

A few days

Where do most blood cells originate?

In bone marrow

Do blood cells divide?

No

What do neutrophils attack?

Bacterial infections

What do lymphocytes attack?

Viruses

What contributes to gas transport?

The structural characteristics of Erythrocytes.

What are the major factors contributing to blood viscosity?

Erythrocytes

What biconcave discs are anucleate and have no organelles?

Erythrocytes

What contains the plasma protein which provides flexibility to change shape?

Erythrocytes

Do erythrocytes have mitochondria?

No

What does Hb bind reversibly with?

Oxygen

Hemoglobin structure:

-Protein globin: 2 alpha and 2 beta chains
-Heme pigment bonded to each globin chain

Each Hb molecule can transport ________.

Four O2

Oxyhemoglobin

Ruby red

Deoxyhemoglobin

Dark red

O2 loading in the lungs produces what?

Oxyhemoglobin

O2 unloading in the lungs produces what?

Deoxyhemoglobin

CO2 loading in the tissues produces what?

Carbaminohemoglobin

Hematopoiesis (hemopoiesis)

Blood cell formation (can make all different formed elements/RBCs, WBCs, and platelets)

Where does hematopoiesis occur?

In red bone marrow (girdles and proximal epiphyses of humerous and femur)

Hemocytoblasts (hematopoietic stem cells)

-Gives rise to all formed elements
-Hormones and growth factors push the cell toward a specific pathway of blood cell development
-New blood cells enter blood sinusoids

Erythropoiesis

Red blood cell production

A hemocytoblast is transformed into a __________.

Proerythroblast

A proerythroblast develops into an early __________.

Erythroblasts

What are the 4 phases in erythropoiesis development?

1. Ribosome synthesis
2. Hemoglobin accumulation
3. Ejection of the nucleus and formation of reticulocytes
4. Reticulocytes then become mature erythrocytes

Reticulocyte

Early RBC

Viscosity

Thickness of blood

Erythropoietin (EPO)

-Direct stimulus for erythropoiesis
-Released by the kidneys in response to hypoxia
-Increasing retic count in 1-2 days
-"Blood Doping"

Causes of hypoxia:

-Hemorrhage or increased RBC destruction
-Insufficient hemoglobin (iron deficiency)
-Reduced availability of O2 (high altitudes)

Building blocks

-Amino acids
-Lipids
-Carbohydrates

Where is Iron stored?

-In Hb
-Liver
-Spleen
-Bone marrow
-Cells (ferritin and hemosiderin)

What is the lifespan of a RBC?

100-120 days.

What is the "RBC graveyard?"

RBCs are engulfed by macrophages in the spleen

Anemia

Blood has an abnormally low O2 carrying capacity.

S & S of Anemia

-Fatigue
-Paleness
-SOB
-Chills

What do we look at to detect anemia?

-Capillary refill (2 secs)
-Conjunctiva
-Lips

Hemorrhagic anemia

Acute or chronic loss of blood (GI bleed)

Hemolytic anemia

RBCs rupture prematurely (mismatched transfusion/infection)

Aplastic anemia

Destruction of inhibition of red bone marrow (drug SE/chemicals/virus)

Pernicious anemia

Autoimmune disorder in elderly (deficiency of vitamin B12)

Thalassemias

-Absent or faulty globin chain in Mediterranean ancestry.
-RBCs are thin, delicate, and deficient in Hgb

Sickle-cell anemia

-Defective gene codes for abnormal hemoglobin (HbS)
-Causes RBCs to become sickle shaped in low-oxygen situations, clogging small vessels, and causing CP and bone pain.
-More common in African Americans

Polycythemia

Excess of RBCs that increase blood viscosity (which impairs circulation)

Normal WBC count

4,000-11,000.

What is the most abundant leukocyte?

Neutrophils

What do neutrophils do?

Kill bacteria

Granulocytes

-Neutrophils
-Eosinophils
-Basophils
(cytoplasmic granules take up dye/loped nuclei)

Polymorphonuclear leukocytes (PMNs)

Neutrophils

What do eosinophils do?

-Digest parasitic worms.
-Elevated in allergies

Basophils

Contain histamine (an inflammatory chemicle that acts as a vasodilator and attracts other WTCs to inflamed sites.)

Agranulocytes

Lymphocytes and monocytes (lack visible cytoplasmic granules/Spherical or kidney shaped nuclei)

T-cells

Act against virus-infected cells and tumor cells

B-cells

Give rise to plasma cells, which produce antibodies.

Monocytes

-Leaves circulation, enters tissue, and differentiates into macrophages.
-Activates lymphocytes to mount an immune response.
-The largest leukocyte

Leukopoiesis

Production of WBCs

Leukopenia

Abnormally low WBC count (drug induced-chemo)

Acute leukemia (AML)

-Involves blast-type cells
-Primarily affects children

Chronic leukemia (CLL)

More prevalent in elderly

S & S of leukemia

-Fever
-Wt loss
-Anemia
-Bleeding
-Death (internal hemmorhage and overwhelming infections)

Platelets

-Form a temporary plug that seals breaks in blood vessels.
-Small fragments of megakaryocytes
-Formation is regulated by thrombopoietin

What do platelets contain?

-Serotonin
-Ca2+
-Enzymes
-ADP
-Platelet-derived growth factor (PDGF)

Circulating platelets

Are kept inactive and mobile by NO (nitrous oxide) and prostacyclin from endothelial cells of blood vessels.

What is the normal value of platelets?

150,000-400,000 ul

Vascular Spasm

Vasoconstriction of damaged blood vessel

What does a vascular spasm trigger?

-Direct injury
-Chemicals released by endothelial cells and platelets
-Pain reflexes

Coagulation

-A set of reactions in which blood is transformed from a liquid to a gel (blood clotting)
-Reinforces the platelet plug with fibrin threads

3 Phases of coagulation

1. Prothrombin activator is formed (intrinsic and extrinsic pathways)
2. Prothrombin is converted into thrombin
3. Thrombin catalyzes the joining of fibrinogen to form a fibrin mesh

Intrinsic Pathway

-Triggered by negatively charged surfaces (activated platelets, collagen, glass)
-Uses factors present within the blood

Extrinsic Pathway

-Triggered by exposure to tissue factor (TF) or factor III (an extrinsic factor)
-Bypasses several steps of the intrinsic pathway, causing it to be faster

Thrombin

Strengthens and stabilizes the clot.

Thrombus

-Clot that develops and persists in an unbroken blood vessel.
-May block circulation, leading to tissue death (MI due to coronary thrombus).

Embolus

A free floating thrombus in the bloodstream.
-Pulmonary emboli impair the ability of the body to obtain O2
-Cerebral emboli can cause strokes

Disseminated Intravascular Coagulation (DIC)

-Widespread clotting blocks intact blood vessels.
-Severe bleeding occurs because residual blood is unable to clot.
-Most common in pregnancy, septicemia, or incompatible blood transfusions.

Petechiae

Red dots on skin

What is the most common blood transfusion?

Packed red blood cells (plasma removed)
-Used to restore oxygen carrying capacity

S & S of a transfusion reaction

-Fever
-Chills
-N/V
-Low BP

Glycoprotein antigens

Determine blood type

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