Hematologic Systems / Hemotopoiesis

Blood delivers ______ and other essential substances throughout the body

oxygen

blood comes into direct contact with virtually every _________ that acts on the organisms

systemic xenobiotic

What can result from exposure to xenobiotics

decreased blood cell production, increased blood cell destruction, alteration of hemoglobin, impairment of coagulation

the response in many cases depends on the ______ and ________ of the xenobiotic as well as the capacity of the system to defend against the insult

nature, quantity

reflecting an incomplete understanding of their causative mechanism

idiosyncratic

the majority of the cells of the blood system are classified as

lymphoid, myeloid

types of lymphoid cells

B, T, NK lymphocytes

types of myeloid cells

erythrocytes, megakaryocytes, granulocytes, monocytes)

marrow spaces within bone begin to form in human at about

the fifith fetal month

After marrow spaces begin to form they become the sole site of

granuocyte and megakaryocyte proliferation

At birth, all marrow contributes to blood cell formation and is red,

containing very few fat cells

extramedullary hematopoiesis in the liver and spleen reemerges as a

compensatory mechanism only under severe stimulation

the hematopoietic stroma consists of

macrophages, fibroblasts, adipocytes, and endothelial cells

a stem cell is capable of _______ as well as differentiation into a specific cell type

self-renewal

stem cells represent only _________ of the nucleated cells of bone marrow

1 in 100,000

Most of these stem cells are usually

quiescent

stem cells are directly responsible for the estimated _______ red cells, __________ platelets, _______ leukocytes produced each day

200 billion, 150 billion, 100 billion

in response to hemolysis or infection

substantially larger numbers of blood cells are produced

what do cytokines do

promote or inhibit the differentiation, proliferation, and trafficking of blood cells and their precursors

cytokines include:

CSFs, interleukins, monokines, interferons, chemokines

Ligands of cytokines receptor family:

growth hormone, IL-2, CSF-1, GM-CSF, gamma interferon, G-CSF

Ligands of the tyrosine kinase family:

kit ligand, insulin-like growth factor-1 receptor

The CD34 antigen is a ______ protein

115 kilodalton

The CD34 antigen is selectively expressed by ____________ shortly after activation

primitive multipotent hematopoietic stem cells

The CD34 antigen is absent in

mature T and B lymphcytes

what is the primary function of the erythron

transport molecular oxygen throughout the organism

for the erythron to function properly

adequate numbers of circulating erythrocytes must be maintained

Homeostasis of erythron proliferation is primarily maintained by the equilibrium between stimulation via

the hormone erythropoietin and apoptosis

what 2 receptors control erythropoietin and apoptosis

Fas, FasL

where is Fas and FasL expressed

of the membranes of erythroid precursors

erythrocytes are removed from circulation at the end of their life span primarily by the action of the

spleen

Erythropoietin is a glycoprotein hormone that is produced in the

epithelial cells lining the peritubular capillaries of the kidney

what stimulates erythropoietin synthesis

anemia and hypoxemia

erythropoietin receptors are expressed in

human erythroid cells, megakaryocytes and fetal liver

The absence of EPO results in

DNA cleavage and erythroid cell death

the mature erythrocyte is a highly specialized cell designed primarily for

oxygen transport

Erythrocytes are densely packed with hemoglobin, which constitutes approximately ____ of their dry weight

90%

the mature erythrocyte had what shape

biconcave discocyte

why is the shape of the mature erythrocyte beneficial

increases surface-to-cell volume

The shape is the net sum of _________ and __________forces within the membrane, surface tension, and osmotic and hydrostatic pressures

elastic and electrostatic

the erythrocyte cytoskeleton consists of hexagonal lattice of proteins, especially

Spectrin, Actin, Protein 4.1

the erythrocyte cytoskeleton proteins interact with ______ and ______ in the membrane to provide a strong but flexible structure to the membrane

ankyrin, band 3

What is the sole source of energy of the erythrocyte?

glucose

how does glucose cross the membrane?

facilitated diffusion mediated by a transmembrane glucose transporter

Name an externally oriented enzyme

acetylcholinesterase

what is the molecular weight of hemoglobin

64,500 Da

the typical adult man has approximately ____ of hemoglobin

1kg

hemoglobin enables blood to transport nearly

100 times as much oxygen as could be carried by plasma alone

the leucon represents all _______ including:

leukocytes, precursor cells, cells in the circulation, large number extrabascular cells

highly specialized mediators of the inflammatory response

neutrophils

_________ involved in antibody production and cell mediated immunity

B and T lymphocytes

immediate but less specific defense that is highly conserved in evolutionary terms

innate immunity

requires several days to develop, unless antigen has previously triggered a response

adaptive immunity

what depolymerizes microfilaments, causing the dissolution of the fibrillar microtubules in granulocytes and other motile cells

colchicine

what 2 pathways are involved in the initiation of coagulation

intrinsic and extrinsic

what is the more important pathway

extrinsic

how is the extrinsic pathway activated

when blood is exposed to tissue factor (thromboplastin)

where is thromboplastin normally expressed

subendothelial cells and fibroblasts not in direct contact with blood

in the resting state, platelets maintain a

discoid shape

the platelet membrane is a typical ______ membrane

trilaminal

on the vessel wall, ______, _______, and _______ are adhesive proteins that play a prominent role in the adhesion of platelets to vascular subendothelium

collagen, vWF, fibronectin

what can activate platelets

thrombin, collagen, epinephrine