BIOL65 CHAPTER 19- BLOOD

Main functions of Circulatory system

Transport, Protection, Regulation

Main functions of Circulatory system- Transport

Moves oxygen from the lungs to body tissues and carbon dioxide back to the lungs. Delivers nutrients absorbed from digestion, hormones from glands, and metabolic wastes for excretion.

Main functions of Circulatory system- Protection

Leukocytes (WBCs) and antibodies in blood defend against pathogens. Platelets and clotting factors prevent excessive bleeding after injuries.

Main functions of Circulatory system- Regulation

Blood helps maintain body temperature, distributes heat, regulates pH, and stabilizes fluid distribution.

Components of the Circulatory system

Heart, blood vessels, blood

Components of the Circulatory system- Heart

Central pump pushing blood through the vessels.

Components of the Circulatory system- Blood Vessels

Arteries carry oxygen-rich blood from the heart, veins return oxygen-poor blood, and capillaries allow exchange with tissues.

Components of the Circulatory system- Blood

Transports gases, nutrients, wastes, cells, and hormones throughout the body.

Components and physical properties of blood

Plasma (55%) and formed elements (45%)

Plasma

55%, Clear, yellowish fluid mostly made of water (92%). Contains proteins (albumins, globulins, fibrinogen), nutrients, electrolytes, hormones, gases, and wastes.

Formed Elements

45%; Erythrocytes, leukocytes, and platelets

Formed elements- Erythrocytes (RBCs)

Heaviest and most abundant cell type, filled with hemoglobin for oxygen transport.

Formed elements- Leukocytes (WBCs)

Defense cells; protect against infection and remove waste.

Formed elements- Platelets

Fragments that assist in blood clotting and tissue repair.

Composition of Blood Plasma

Water and Proteins

Composition of Blood Plasma- Water

Acts as the solvent for nutrients, wastes, and gases; essential for transporting materials.

Composition of Blood Plasma- Proteins

Albumin, Globulins, Fibrinogen, and other solutes

Composition of Blood Plasma- Proteins: Albumin

Maintains osmotic pressure, helping balance fluid between blood and tissues.

Composition of Blood Plasma- Proteins: Globulins

Serve as antibodies and help with immune responses.

Composition of Blood Plasma- Proteins: Fibrinogen

Converts to fibrin in clotting, helping form blood clots.

Composition of Blood Plasma- Proteins: Other Solutes

Electrolytes, nutrients, hormones, gases, and waste products like urea and creatinine.

Erythrocytes- Shape

Biconcave discs increase surface area for efficient gas exchange.

Erythrocytes- No Organelles

Lacks nucleus and mitochondria to maximize hemoglobin content for gas transport.

Erythrocytes- Primary Function

Carries oxygen from the lungs to tissues and helps return CO2 to the lungs for exhalation.

Hematocrit

Measures the percentage of RBCs in blood volume; essential for evaluating oxygen-carrying capacity and anemia.

Hemoglobin Concentration

Indicates hemoglobin level; essential for diagnosing conditions like anemia or polycythemia.

RBC Count

Measures RBC quantity; imbalances can indicate anemia (low RBCs) or polycythemia (high RBCs).

Structure of Hemoglobin

Each hemoglobin has four protein chains (globins), each with a heme group containing iron at its center.

Function of Hemoglobin

The iron in heme binds to oxygen in the lungs and releases it in tissues. Hemoglobin also helps transport a portion of CO2 from tissues back to the lungs.

RBC- Erythropoiesis

Occurs in red bone marrow, where stem cells develop into RBCs under the influence of the hormone erythropoietin.

RBC- Life Span

~120 days; RBCs can't repair themselves due to lack of nucleus.

RBC- Death and Recycling

Broken down in the liver and spleen. Iron is recycled, while heme is converted into bile pigments and excreted.

ABO blood groups

Based on the presence or absence of A and B antigens on RBCs. Blood types (A, B, AB, O) affect transfusion compatibility.

Rh Factor

Determines positive or negative blood type. Rh incompatibility (e.g., Rh-negative mother, Rh-positive fetus) can cause immune reactions.

Antibodies

Attack foreign antigens; transfusion reactions occur if incompatible blood is transfused, leading to hemolysis and possibly severe reactions.

Types of Leukocytes

neutrophils, eosinophils, basophils, lymphocytes, and monocytes

Appearance of Leukocytes- Neutrophils

"First responders" to bacterial infection; phagocytize bacteria and release antimicrobial agents.

Appearance of Leukocytes- Eosinophils

Attack large parasites, modulate allergic responses, and help manage inflammatory chemicals.

Appearance of Leukocytes- Basophils

Release histamine to increase blood flow and heparin to prevent clotting, aiding other WBCs.

Appearance of Leukocytes- Lymphocytes

B cells produce antibodies; Memory B cells retain knowledge of pathogens for future responses. T cells kill infected or abnormal cells.

Appearance of Leukocytes- Monocytes

Become macrophages, engulf dead cells and pathogens, activate immune response.

WBC- Leukopoiesis

Stem cells in bone marrow differentiate into various WBCs depending on chemical signals like interleukins.

WBC- Life Span

Short in circulation (hours to days), longer in tissues (months to years).

WBC- Production

Occurs in the bone marrow; each WBC type forms as needed.

WBC- Death

Most die after fighting infection, removed by spleen or liver; prevents buildup that could trigger inflammation.

Platelets- Structure

Small, no nucleus; fragments of megakaryocytes.

Platelets- Primary function

Form platelet plugs to stop bleeding and release chemicals to support vessel repair and immune response.

Platelets- Hemostasis

Platelets stick to damaged vessel walls, creating a temporary "plug."

Platelets- Additional Roles

Release growth factors, attract WBCs to the site, dissolve clots when repair is complete, and destroy invading bacteria.

Platelets- Thrombopoiesis

Megakaryocytes shed fragments in bone marrow, becoming platelets.

Platelets- Lifespan

~10 days; constantly replenished from bone marrow.

Hemostasis- Vascular Spasm

Constriction of blood vessels immediately after injury to reduce blood flow.

Hemostasis- Platelet Plug Formation

Platelets adhere to exposed collagen in vessel walls, forming a temporary plug.

Hemostasis- Coagulation

Fibrin strands weave through the platelet plug, creating a stable clot to halt bleeding.

RBC Disorder- Anemia

Low RBCs or hemoglobin; reduces oxygen delivery, leading to fatigue and weakness.

RBC Disorder- Polycythemia

Excess RBCs; thickens blood, raising risk of clotting and strain on the heart.

WBC Disorder- Leukopenia

Low WBC count; compromises immune defense, increases infection risk.

WBC Disorder- Leukemia

High WBC count; uncontrolled WBC growth, often cancerous, affects immune function.

Platelet Disorder- Thrombocytopenia

Low platelet count; increases bleeding risk and can complicate healing.