Ch 9 Blood Flashcards
What is Blood?
- a fluid connective tiss that circulates through the cardiovasc sys
- 6 L total vol, 7-8% total body weight in adult
Functions
- transport nutrients and O2, directly or indirectly to cells
- transport wastes and CO2 away fr cells
- delivery of hormones and other reg substances to and fr cells and tiss
- maintenance of homeostasis by acting as a buffer and by participating in coagulation and thermoreg
- transport of humoral agents and cells of immune sys, that protect body fr patho agents, foreign proteins, and transformed cells. Ex: cancer cells
Components:
*hematocrit
- erythrocytes: 5 x 10^12 cells/L of blood
- leukocytes: 7 x 10^9/L of blood
- platelets
- plasma: 1% of blood (along w/ leukocytes)
*vol of packed erythrocytes in a sample of blood
What is plasma?
- liquid extracellular material that imparts fluid properties to blood.
- more than 90% of weight is water
- serves as a solvent for many solutes
Plasma components
*interstitial fluid of conn. tiss is derived from blood plasma
- albumin
- globulins
- fibrinogen
Albumin:
- main protein constituent
- smallest plasma protein, made in liver
- responsible for exerting the conc. gradient bet. blood and extracell tiss. fluid
- act as an carrier protein for hormones, metabolites, and drugs
Globulins:
- immunoglobulins: largest component (y-globulins)-antibodies
- non-immune globulins (a,B-globulins)
- secreted by liver
- maintain osmotic pressure, serve as carrier proteins
- include, fibronectin, lipoprotein, coagulation factors, other molecules
Fibrinogen:
- largest protein made in liver
- transformed into fibrin: forms insol clot in event of damage to blood vessel
What are erythrocytes?
- anucleate, biconcave disks, devoid of typical organelles
- to bind O2 for delivery to tiss, in exchange bind CO2 for removal fr tiss.
- its shape max’s surface area, important for gas xchange
- 120 days lifespan, phag by macrophage in spleen, bone marrow, liver
- deformable, allowing to pass easily through smallest vessels
Shape of erythrocytes maintained by:
- lipid bilayer
- integral membrane protein
- peripheral membrane proteins
- gives elastic properties and stability to membrane
- contain hemoglobin, specialized protein for transport of O2 and CO2
- consists of 4 polypeptide chains
What are platelets?
- small membrane-bounded anucleate cytoplasmic fragments derived from megakaryocytes-large polyploidy cells whose nuclei contain multiple sets of chromos.
- discoid structures about 2-3 um
- lifespan 10 days from bone marrow
4 zones of platelets
- peripheral: thick coat of glycocalyx receptors
- structural:
- organelle
- membrane:channels
Function of platelets
- continuous surveillance of blood vessels, blood clot formation, repair injured tiss
- survey endothelial lining of blood vessels for gaps and breaks
- when a blood vessel is injured or broken, platelets adhere to the exposed tiss at the damaged site
- primary hemostatic platelet plug
- secondary hemostatic plug
Formation of Blood cells (Hemopoiesis):
- erythropoiesis
- leucopoiesis
- thrombopoiesis
- initiated in early embryonic dev’t
- yolk sac phase
- hepatic
- bone marrow
Describe Erythropoiesis
- develop from Myeloid stem cell
- with help of Erythropoietin (which is a glycoprotein secreted by kidney, in response to decreased blood [O2] and regulates formation and release)
1a. myeloid stem cell
1. proerythroblast: large cell, spherical nucleus, presence of free ribos.(->mitosis)
2. basophilic erythroblast: smaller, large # of free ribos(polyribos) that syn hemoglobin
3. polychromatophillic ery: gray or lilac color, shows both acidophilic and basophilic staining of cyto
4. orthochromatophillic (normoblast): small, compact, densely stained nucleus. no longer capable of division. increased acidophilic cyto.
5. polychromatophilic ery: extruded its smaller nucleus. coarse hematocrin granules form a checker-board pattern that helps this cell type. ready to pass into sinus of bone marrow
- these polyribos impart slight basophilia to otherwise eosinophilic cells-can be demo w/ special stains that cause them to clump and form reticular network called Reticulocytes (1-2% of total RBC count)
- mitosis occurs in 1,2,3 and released into circulation as soon as formed
Describe Granulopoiesis
- Myeloblasts
- Promyelocytes-only cells to produce azurophillic granules(large, spherical nucleus
- Myelocytes-first exhibit specific granules(spherical nucleus, becomes heterochromatic and acquires distinct indentation during subsequent divisions)
- cell div stops - Metamyelocyte-neutrophil, eosinophil, and basophil lines can be indentified by the presence of numerous specific granules
*cytokines are glycoprotein hormones and stimulating factors that reg all stages of hemopoiesis.
Describe Monocyte Development
- Monoblasts
- The multipotential myeloid stem cell (CFU-GEMM) also gives rise to cells that develop along the monocyte-macrophage pathway
- takes about 55 hours and the monocytes remain in the circulation for about 16 hours befor emigrating to tissues where they differentiate into macrophages.
Describe Megakaryocyte Dev’t
- multipotential myeloid stem cell (CFU-GEMM)
2. CFU-Meg Cell -> megakaryocyte->megakaryoblast->megakaryocyte->platelets
Lymphopoiesis
- Granulocytes
- Agranulocytes
*multipotential lymphoid stem cells (CFU-L) originate in bone marrow
- promyelocytes->myelocytes->metamyelocytes
- monoblasts->monocytes->macrophage
Where is bone marrow found?
- in medullary cavity of young long bones and the spaces of spongy bone
- is a closed circulation, where newly formed blood cells must penetrate the endothelium to enter circulation.
- those not active in blood formation contain adipose cells, giving it the appearance of adipose tiss.
Leukocytes:
- Agranulocytes
- Granulocytes
- cell that lacks specific granules (lymphocytes, monocytes)
- cells containing specific granules (neutrophils, eosinophils, basophils)
*both contain nonspecific azurophilic granules-lysosomes
Neutrophils
- most numerous WBCs and most common granulocyte.
- larger than ery
- 3 types of granules: 1. specific 2. azurophilic 3. tertiary
- are motile cells. leave circulation and migrate to their site of action in conn. tiss.
- are phagocytes at site of inflammation
- 3 lobes in nucleus
- inflammation and wound healing also involve monocytes, lymphocytes, eosinophils, basophils, fibroblasts
- eosinophils and lymphocytes are more commonly found at sites of chronic inflammation
What is Yellow Bone Marrow?
- inactive bone marrow
- found in medullary cavity of bones in adult, that are no longer hemopoietically active (long bones of arms, legs, fingers, and toes)
- retains its hemopoietic potential, and when necessary, as after severe loss of blood, it can revert to red bone marrow
- by extension of hemopoietic tiss into yellow bone marrow
- repop of yellow bone marrow by circulating stem cells.
Eosinophils
- large, eosinophilic, refractile granules in cytoplasm
- same size as neutrophils, bilobed (2-lobed) nuclei
- 2 types granules: 1.specific 2. azurophil
- associated w/ allergic reactions, parasitic infections, chronic inflammation
- 2 lobes in nucleus
Basophils
- least numerous of WBC’s, <0.5% of total leukocytes
- 2 types granules: 1. specific 2. azurophilic
- function like mast cells. react w/ IgE to release vasoactive agents for severe vascular disturbances associated w/ hypersensitivity and anaphylaxis
- cant see nucleus because of all granules
Lymphocytes
- most functional cells of lymphatic or immune sys.
- recognize/respond to antigens
- size of ery
- 3 types: 1. T lymphocytes(differientiate in thymus) 2. B lymphocytes(bursa) 3. NK cells(kill certain types of transformed cells)
3 types of T lymphocytes:
*mediated by surface molecules
- cytotoxic CD8+ T lymphocytes
- Helper CD4+ T lymphocytes
- Suppressor and/or cytotoxic CD8+, CD45RA+, T lymphocytes
-60-80% of lymphocytes are T lymphocytes
Monocytes
- largest WBC
- precursor of cells of mononuclear phagocytotic sys
- travel from bone marrow to body tiss
- transform into macrophage, which function as antigen-presenting cells in immune sys
- phago bacteria, other cells, and tiss debris