Erythrocytes and Thrombocytes

RBCs (Erythrocytes)

• These are the blood's most abundant cells, responsible for tissue oxygenation
• Erythrocytes contains hemoglobin which carries gases and electrolytes, and regulates diffusion through the cell membrane
• Mature erythrocytes cannot synthesize protein or carry out oxidative reactions due to the lack of a nucleus and cytoplasmic organelles, therefore they cannot undergo mitotic division
• Erythrocytes have a limited lifespan of about 100 to 120 days
• Erythrocytes size and shape is biconcave, and are reversibly deformed for great gas transportation

Platelets (Thrombocytes)

• Platelets refers to irregularly-shaped cytoplasmic fragments since platelets are not true cells
• Platelets are essential for blood coagulation and bleeding control
• Megakaryocytes undergo fragmentation and platelets are formed as a result
• A platelet circulates for about 10 days and is removed by macrophages of the MPS, mostly in the spleen, as it ages
• Injury to blood vessels causes platelets to release contents of cytoplasmic granules which are pro-inflammatory biochemical mediators

Hemoglobin (Hb)

• It's the erythrocyte's oxygen-carrying protein, and erythrocytes contain as many as 300 hemoglobin molecules
• Oxygen is taken up by Hb-packed RBCs in the lungs, and Hb increases the blood's oxygen-carrying capacity by 100-fold and is responsible for the red blood cell's color.
• Two pairs of polypeptide chains (globins) make up every Hb molecule
• Four colorful complexes of iron plus protoporphyrin compose (the hemes)
• Polypeptide chains includes alpha, beta, gamma, delta, epsilon, or zeta.
• Hemoglobin A is the most common type in adults
• Fetal hemoglobin is the most commonly found type, Hemoglobin F

Heme

• It refers to large, flat, iron-protoporphyrin disk that is synthesized in the mitochondria, and transports oxygen
• Each hemoglobin molecule can transport four oxygen molecules given an individual hemoglobin has four hemes

Protoporphyrin

• Bound with ferrous iron, produced by complex four-ringed molecule through a series of complex biochemical reactions.
• Ferrous iron (Fe²+) can bind oxygen in the lungs and release it in the tissues where oxygen concentration is less
• Ferric iron (Fe³+) cannot bind oxygen in the lungs and release it in the tissues where oxygen concentration is less.

Oxyhemoglobin

• Temporally oxidizes as oxygen binds to ferrous iron (Fe²+) and reduces with the body after oxygen releases, and binds oxygen

Deoxyhemoglobin

• Reduced hemoglobin reactivates as it regains hemglobin's ability to bind oxygen

Methemoglobin

• Oxygen-carrying metalloprotein hemoglobin has iron in the heme group at in the state of Fe³+ (ferric)
• It cannot bind oxygen without reactivation by methemoglobin reductase, and carries oxygen

Granulocytes

• They are capable of amoeboid movement, migration through vessel walls to sites where their action is needed, is short-lived and highly motile, and take 14 days to develop from early precursors but infection will accelerate it
• Phagocytes (neutrophils, basophils, and eosinophils) are granulocytes since these have enzymes capable of destroying microorganisms and catabolizing debris ingested during phagocytosis, as well as biochemical mediators that have inflammatory and immune reactions
• Stem cells in bone marrow are used in gramauloctye formation

Neutrophils

• Band/stabs are immature neutrophils while segmented neutrophils are mature, can be further subdivided
• Segs refers to Segmented neutrophils
• They have banded and form part of the polymorphonuclear cell family ("PMNs") together with basophils and eosinophils
• Neutrophils, constituting 55% of the total leukocyte count in adults, serve as chief phagocytes of early inflammation
• They ingest and destroy at sites of inflammation and stimulates syntheses of vasoactive lipid molecules and cytokines
• They normally ingest and destroy then die in 1-2 days. Dead neutrophils release enzymes for healing and dissolving of debris

Basophils

• Secretes cytokine IL4 to guides B cell differentiation toward plasma cells, contains mixtures of mediators like histamine and heparin, and guides differentiation of B cells towards secreting IgE with plasma
• Occurs the least, with large and coarse granules and increases with inflammatory and parasitic reactions

Eosinophils

• Eosinophils ingest antigen antibody complexes and viruses and are induced by mast cell chemotactic factor, and phagocytes parasites, controls allergic reactions
• Eosinophil secondary granules have toxic compounds highly destructive to parasites and viruses
• Eosinophil granules secrete enzymes that help control inflammatory reactions and large numbers of eosinophils produce asthmas and allergic reactions which indicates 1 hypersensitivity

Mast cells

• Similar to basophils, mast cells different set of precursor cells in the bone marrow but found on body epithelial surface
• It activated and increases blood vessel permeability and smooth muscle contractions, and has a key role in inflammation and healing

Monocytes

• Formed and launched from bone marrow into the bloodstream as unilobar/shaped amoeboids that are stored in the spleen where they migrate into fully mature cells
• These mature tissues called tissue macrophages and myeloid dendritic cells serve as type of white blood cells/leukocyte
• Responds to inflammation signals quickly (8-12hrs) to infection spots in tissues then divides differentiates as myeloid cells, elicits immune responses, replenish macrophages in normal state, and have 2%-10% all leukocytes in the human body

Macrophages

• Responsible for the removal of damaged cells and initiates healing by ingesting host & defective ones in blood cells, remove contaminants infection by T cells
• Engulfs/digests particles of debris to defend the body through phagocytosis, as well as recruit adaptive (lymphocytes) processes & critical play
• Functions to replenish resident macrophages under normal states & survive for years

Lymphocytes

• Primary immune cells that do not contain digestive vacuoles
• They can have development in blood by T & phagocyte cells, reside secondary lymphoid tissues, reside secondal lymphoid tissues, and survive for years

Natural killer cells

• Functions to eliminate cells & virally infections by killing some types of tumor cells & produce cytokines to regulate immune
• Unlike natural killer cells which are T & phagocyte activator to kill some types, it develops in bone marrow circulating
• Resemble lymphocytes, they are mostly peripheral blood & spleen & the functions of regulation are cytokines

Hematopoiesis

• Blood cell production that constantly goes on in the liver & spleen of the fetus & marrow's medullary after birth Prenatally is the yolk stack, liver during 8wks/gestation after marrow (5th month) before birth. marrow remains site
• For adults. in the bones & lymph involving mitotic/undifferentiated replication into mature forms after biochemical stimulation as protection to replace death destroyed & killed. Greater chronic increases rather than acute in marrow & primary residence of hematopoietic stem cells in bone cavities. There are 2 kinds: red that is myeloid, active, or hematopoietic vs yellow inactive/fat responsible for yellow and located humerus, vertebre, skull, mandible but limited proximal.
• Stem cell populations exist in bone marrow niches composed with progenitor cells: Hematopoietic (HSCs) in progenitor stem to make replacements through continuous self and differentiation Marrow hematologic involves regualted signaling like stem, cell, stem maintained differentiated to provide microenvironments Niches involve osteoblastic around surface cell, cell & CAR, and nestin expression also in vascular or endothelial containing sinus, and nestin with more.

Processes

A division into stem in cell product to renew progenitor and maintain, and also marrow pool where cells divide maturing vessels through marrow as reservoirs. Also a division of blood through vasculature with marination of reservoir cells for immune response, moving with inflammatory processes, Rapid depletion triggers medullary acceleration from marrow yellow to red or faster stem and progenitor differentiation. Underlying regulation is secretion of erythropoietin, kidney & compensation as altitude or tissues lowers oxygen or is damaged.

Erythropoesis Location/Processes

• In marrow progenitor cells proliferate and differentiate into big nucleated committed ones like in enthron location of stem cells as division occurs As ribosomes produce intermediaries, elimination occurs in a process that is in the bone with hgb synthesized to a normacyte. Then disk like reticulocytes with polyrib. or mitochn after 24-48hrs lose function so venous vessels & spleen help further mature
• Body circulatory has the ability to create 1% every 24 hours (Ritic count)
• Oxygen reduction responds through chemoreceptors brain, breathing or stimulating peritubular kidney to release synthesis with 2 pathways

Nutritional Needs

• Proper environment, adequate products & building (Protein and minerals) like B6 with hemoglobin vitamins (B12, C, E), result reduced erythropoiesis due to B12
• B12 most absorption, IF problems lead pernicious anemia due to vitamin/DNA Folate is necessary Requirements: 25mg iron (1-2 dietary & transferrin) so transferrin bonds macrophages & ferritin, and also (IF)

Iron Cycle

• Requires transferrin receptor bind plasma, moves cell by endocytosis then transfers or releases

Hemostasis

• Requires vitamins related normal clotting factors that are limited by regulation when vitamin K lacking, occurs when needing to arrest bleeding when 3 components interact

Sequences

1 Damage vessels by constriction arteries to prevent or limit flow to sites that exposes prothrombogenics for adhering during vessels and create plugs prevent to bleeding (primary hemostasis) 2 Factors as endothelium help secreted platelets to stop clotting in system until Fibrin is formed & prevents bleeding more also (secondary hemostasis) Platelets work also (fibrin) for more resolution and control w/fibinolysis

Vessel Interaction

Vasodilation & inhibition by proteins happens through active & L-arg & Prostagalandin interaction & endethlin

Platelets

• Normal quantities are as normal while anything below is thrombocytopenia or a thrombosis with stroke etc for high elevations Its role: Constriction regulated (1), adherence triggers vessels (2), activation helps cascade stabilizes (3,4) then repairs or removes (fibrinolysis)

Triggers and steps

• Vessel wall triggers adhesion
• Activation from chemicals in platelet triggers shape change
• Aggregation with cells of both & then platelets

Clotting

Lead to activation, mesh for mobilization with platel & contain 3 types and hemostasis factor from thrombins or fibrinogen Extrinsic/tissue help reaction with high factors while 1% already helps NOTE: K deficiency prolonged time

Spleen

Largest Lymph organ. It holds cells, monocytes to engulf foreign particles:

• Red pulp has the most macrophage (filtration, blood). with white lymph arounds
• The sinus makes a barrier around, and all together work

Splenectomy

• Blood broadens, increases
• Leukocytosis -Platelet elevated
• Reduced defenses
• Complications: Septic infection, medication, & thrombosis

Lymph Nodes

They collect fluid and circulate which drain to superior cava

Functions

Antigens contact 1st for action on pathogens -T cells mostly paracortex / macrophages filter or present antigens as well as capture them together to signal/organize follicles/secondary There is a response particularly to antigen which is why enlarged.

Problems

They will act to reject when enlarged unless reaction from trauma

• Localized affect area
• General from non & malignant disease

Immune Processes & Type 1 Allergic Reactions

• In granules. Histamines help control with eosiniphilia
• Affect fluid volume & flow of molecules-water across cap but with Albumin. A deficiency could cause more movement & decreased flow

Erythrocytes, the most abundant blood cells, facilitate tissue oxygenation via hemoglobin. Thrombocytes, or platelets, are vital for blood coagulation. Both have limited lifespans and are removed by macrophages.