Blood - First-year nursing anatomy and physiology exam notes PDF

Preview

Summary

First-year nursing anatomy and physiology exam notes...

Description

Lecture 4: Blood Tuesday, October 2, 2018

3:18 PM

3 visible layers of blood: - Plasma 55% - Buffy coat 1% - Erythrocytes (hematocrit, 44%) Overview of Blood Functions - Exchanging gases - Distributing solutes - Performing immune functions - Regulated body temperature - Blood clotting - Maintaining acid-base balance - Stabilize blood pressure Plasma: - Mostly water - Plasma proteins: ○ Albumin - creates colloid osmotic pressure ○ Immune proteins (antibodies) ○ Transport proteins ○ Clotting proteins Erythrocyte life cycle: - RBC's live about 120 days - Erythropoiesis is the production of RBC's Erythropoiesis - Regulated by a negative feedback loop - Low blood O2 concentration - Detected in kidneys - Release of erythropoietin - Erythropoiesis rate increases and faster maturation

-

Increase hematocrit What is an expected finding related to reticulocytes during increased erythropoiesis?

Anemia: - Related to either/both: ○ Hemoglobin ○ Hematocrit - Sign and symptom of anemia: - Physiological consequences of anemia: ○ O2 delivery to tissues ○ O2 delivery to tissues Leukocytes and Immune Function Leukocytes: Granulocytes: Neutrophil, Eosinophil, Basophil

Agranulocytes: Lymphocyte, Monocyte

Granulocytes: - Neutrophils - most common leukocyte ○ Highly active phagocytes that destroy bacteria ○ Attracted by chemotaxis of injured cells ○ Enhance inflammation - Eosinophils ○ Phagocytes ○ Important in conditions r/t allergies and parasites ○ Mediate inflammation - Basophils - Mediate inflammation Agranulocytes (no cytoplasmic granules) - Lymphocytes ○ B lymphocytes produce antibodies for specific antigens ○ T lymphocytes receptors of antigens, activate other parts of immune system - Monocytes

○ ○

Macrophages Activate other immune components

Complete blood count - Blood test to assess populations and characteristics of formed elements ○ RBC characteristics - size, volume, and concentration of hemoglobin in cytosol ○ Platelet count and volume ○ Numbers and types of leukocytes Leukopoiesis: formation of leukocytes. Platelets: - Small cell fragments surrounded by plasma membrane - Smallest of formed elements - Involved in homeostasis - No nuclei, missing most organelles - Live 7-10 days - Granules - clotting factors, enzymes, glycogen, mitochondria - Cytoskeletal microtubules Thrombopoiesis: structure and formation of platelets Hemostasis: 5 significant events, number 1 function is to limit significant blood loss 1. Vascular spasm ○ Vessel injury means blood in extracellular fluid ○ Vasoconstriction: § Tissue pressure increases § Vessel diameter decreases § BP and flow at injury site decrease 2. Platelet plug formation ○ Exposed collagen fibres ○ Endothelial cells release von Willebrand Factor (vWF) ○ Platelets activated and bind to site / each other ○ Platelet granules promote platelet recruitment ○ Continued platelet attraction and binding to covered injured vessel 3. Coagulation ○ Coagulation cascade

2 pathways: intrinsic and extrinsic / tissue factor that merge at common pathway § End goal is activation of fibrin § Fibrin is necessary to secure platelet plug § Precursor fibrinogen is readily available in plasma and platelets but must be activated into fibrin § Clotting factors (typically proteins) required in the process § 2/7/9/10 depend on vitamin K for their synthesis ○ Intrinsic / contact activation - Factors contained in the blood - Collagen fibers in damaged vessel exposed - Each factor must change from inactive to active from XII to XIIa to trigger the next step in the process - Extrinsic / Tissue Factor - Started by factors outside the blood - Tissue factors (TF/3) displayed by damaged subendothelial cells ○ Common Pathway - 10+5+Ca - Prothrombin (2) - Thrombin - Fibrinogen (1) - Fibrin: used to secure and reinforce the platelet plug allowing the underlying tissues to heal without ongoing blood loss Clot retraction - Actin and Myosin fibres contract to bring wound edges closer Thrombolysis - Tissue plasminogen activator (tPA) released by endothelial cells or Urokinase released but kidneys begins process: § Plasminogen activated into plasmin, breaks down fibrin, and clot dissolves §

4. 5.

Preventing unwanted clotting: - Clotting is a positive feedback loop and must be closely controlled - Endothelial cells produce/secrete 2 chemicals that regulate first /second stages of clot formation...