Blood components and Body fluids

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Body Fluids

• Body fluids include plasma and erythrocytes
• Every living cell needs resources like oxygen, fuel, and a way to dispose of byproducts through cellular respiration
• Some organs have direct access to resources, but most do not
• The body ensures that cells obtain necessary resources to meet their energy needs, regardless of their location

Blood

• Classified as a built-in delivery service, actively propelled and free-flowing
• Serves as a transport medium for solutes, water, and heat
• Contains multiple components suspended in watery plasma
• Plasma proteins stabilize osmotic balance
• Erythrocytes and carrier proteins facilitate transport
• Leukocytes and antibodies fight infections
• Platelets and fibrinogen perform hemostasis
• Blood types are determined by cells' surface composition

Hematocrit Test

• Demonstrates the multiple components of blood
• About 12% of body fluid, also the most active kind
• Plasma is more complex than other body fluids (CSF, endolymph, mucus, etc.) because it performs dozens of functions

Body Water Content

• Infants have 73% or more water due to low body fat and less calcified skeleton
• Adult males have ~60% water due to higher muscle mass, which carries more water
• Adult females have ~50% water due to higher body fat %, which carries less water
• Water content declines to ~45% in old age
• Adipose is the driest tissue, while compact bone is the second
• Muscle, blood, and loose fibrous types are water-rich
• Total body water is ~40L for an average adult

Fluid Compartments

• Two main fluid compartments within the human body:
• Intracellular Fluid (ICF): liquids inside cells, 40% of body weight, 25 L
• Extracellular Fluid (ECF): liquids outside cells, 20% of body weight, 15 L
• Plasma: 3L in heart & blood vessels
• Interstitial Fluid (IF): 12 L in spaces between cells
• Some IF is also known as Transcellular Fluid (TF): lymph CSF, humors of the eye & ear, synovial fluid, serous fluid, mucus, gastrointestinal secretions

Interstitial Fluid

• Defined as being in the gaps between tissues
• Also known as tissue fluid
• Interstitium is all the gaps it's in

Blood Plasma

• Carries resources to the interstitial fluid from their source organs and waste products from IF to organs of elimination
• Individual cells absorb what they need from the Interstitial Fluid (IF) and release their wastes into it
• Intracellular fluid maintains a chemically stable environment while obtaining resources

Composition Similarities

• Plasma and interstitial fluid are chemically similar due to constant exchange and free mixing.
• Plasma and interstitial fluid are high in Na+, Cl-, HCO3- and low in K+, Mg2+, HPO42-
• Plasma has more proteins
• Intracellular fluid exchanges materials under the cell's control, allowing it to maintain a distinct mix of high and low solutes

Concentration of Solutes

• High Na+ outside cells, high K+ inside cells
• Plasma contains:
• 90% water, dissolving and suspending medium for solutes, absorbs heat, transports and distributes thermal energy and solvent for dissolved materials
• Electrolytes: Maintain osmotic pressure
• Plasma Proteins: Contribute to viscosity of blood, most facilitate lipid transport
• Albumin: Contributes to osmotic pressure and maintain water balance in blood and tissues
• Globulins: Produced mostly by the liver and transport proteins that bind to lipids, metal ions, and fat-soluble vitamins
• Alpha is for copper & hemoglobin transport, triggering coagulation
• Beta is for iron transport and defense
• Gamma globulin antibodies that fight infection
• Fibrinogen that is produced by liver forms fibrin threads of blood clots

Plasma Additional Substances:

• Nonprotein nitrogenous substances are by-products of cellular metabolism and include urea, uric acid, creatinine, and ammonium salts
• Nutrients (organic) Materials come from the digestive tract Include glucose and other simple carbohydrates, amino acids (protein digestion products), fatty acids, glycerol and triglycerides (fat digestion products), cholesterol, and vitamins, Fuel and building materials necessary for cells.
• Respiratory gases Oxygen and carbon dioxide oxygen mostly bound to hemoglobin inside RBCs carbon dioxide transported, are dissolved as bicarbonate ion or CO2, or bound to hemoglobin in RBCs O2 & CO2 (cellular respiration!)
• Hormones Steroid and thyroid hormones carried by plasma proteins, others flow free communication by the endocrine system

Consequences of Low Dietary Protein

• Lack of dietary protein shuts down plasma protein production causing Albumin and globulin levels to fall
• Osmotic imbalance causes water to leave plasma and seep into the ventral body cavity, i.e. Kwashiorkor

Formed Elements

• Include whole or incomplete cells
• Almost entirely generated in bone marrow
• Derived from hemopoietic stem cells
• Erythrocytes ~45% of whole blood
• Leukocytes & platelets = "buffy coat" ~1% of the volume of whole blood
• Plasma ~55% of blood

Erythrocytes

• Most plentiful of the formed elements, also known as "red blood cells."
• Biconcave disc-shaped and lacks a nucleus
• Flexible and stackable
• Very small by cell standards
• About 1/4 of the cells are erythrocytes, That's 20-30 trillion.
• Small size, round shape, and ability to stack let erythrocytes pass easily through capillaries which allows them to reach practically every cell that needs O2 delivered or has CO2 to get rid of.
• "Red blood cell" is a nickname and convenience for abbreviation (RBC), not the official term for these cells; always call them erythrocytes

Hemoglobin

• Gas-carrying protein molecule
• Made of 2 pairs of polypeptide chains that can hold 2 CO2 total
• Has 4 heme groups that can hold one O2 each totaling 4
• Has 250 million hemoglobins per RBC = ~6.25 billion trillion in whole body
• Iron loosely connects to oxygen molecules long enough for transport
• Iron within the heme groups loosely binds to O2 and turns oxygen-rich blood crimson.
• Blood turns maroon when O2 leaves the iron and moves into the interstitial fluid

Erythropoiesis

• Production of erythrocytes occurs in red bone marrow
• Generates ribosomes and hemoglobin to make erythrocytes,

Erythropoiesis Steps

• Hemocytoblast, aka hemopoietic stem cells,
• Colony-forming unit(CFU)
• Erythrocyte CFU
• Erythroblast
• Reticulocyte ejects the nucleus
• Mature Erythrocyte with a life span of ~4 months and migrates from red marrow to blood

Erythropoietin

• RBC production must keep up with how frequently the erythrocytes wear out and/or are lost to injury, menstruation, etc.
• Too few erythrocytes are called anemia and limit the blood's delivery of O2 affecting energy-using tissues' metabolism
• Too many erythrocytes are called polycythemia and mean thickness of the blood and raising the BP and straining the heart and blood vessels.

Erythrocyte Life Story

Nutrients like Amino acids, Iron, Folic acid, and Vitamin B12 are absorbed

• Hemoglobin raw materials conveyed by plasma proteins (= transferrin) from the gut to red marrow
• Hemopoietic stem cells are stimulated by EPO to produce new erythrocytes
• Erythrocytes circulate for about 120 days, continuously circulating and wearing away at RBCs, which cannot self-repair without a nucleus
• Worn-out erythrocytes are "recycled" in the spleen, liver, or red marrow
• Cell fragments are then phagocytized
• Pieces of erythrocyte (plasma membrane) of are consumed by macrophages and broken down for lipids, etc.
• Hemoglobin gets degraded
• Pieces of Heme groups' iron are recycled, while the rest is degraded into bilirubin and excreted in bilirubin and excreted in feces.
• Finally, hemoglobins' polypeptide chains get catabolized used for amino acids

Causes of Anemia

Some possible causes of deficient RBC's and anemia:

• Genetically slow rate of production e.g. erythropoietin deficiency
• Accelerated rate of destruction e.g. hemolytic anemia
• -Faulty produced e.g. thalassemia
• Genetically-faulty hemoglobin produced (e.g. sickle-cell anemia)
• Dietary iron deficiency
• Temporary iron deficiency due to bleeding injury or menstruation
• Impaired hemoglobin function e.g. carbon monoxide poisoning

Sickle Cell Anemia

• Hemoglobins with no attached O2 adhere to one another
• The long chains press on the plasma membrane until the cell folds over into a "sickle".

Blood Recap

• Our body's only propelled, free-flowing body fluid
• The transport medium for solutes, water, and heat
• Plasma proteins stabilize osmotic balance
• Erythrocytes and carrier proteins facilitate transport
• Leukocytes and antibodies fight infections
• Platelets and fibrinogen perform hemostasis
• Blood typing

This quiz covers the composition of blood, including plasma, interstitial fluid, and cellular components. Explore the critical roles of erythrocytes, plasma proteins, and platelets. Understand fluid distribution and electrolyte balance within the body.