blood

Blood and interstitial fluid

Cells needs are met by which 2 fluids?

Interstitial fluid

The fluid that bathes the body’s cells

Diffusion is the mechanism between:

Blood→ interstitial fluid→ cells and

Cells→ interstitial fluid→ blood

Functions of blood

1. Transport of dissolved substances

2. Regulation of pH and ions

3. Restriction of fluid losses at injury sites

4. Defense against toxins and pathogens

5. Stabilization of body temperature

General characteristics of blood

• 38 degrees Celsius at body temp

• Alkaline

• Blood volume liters= 8% of body weight(Female and make between 4-6 liters)

Composition of whole blood

Water(92%)

Plasma proteins(7%)

Other solutes(1%)

Plasma in blood composition

Plasma proteins do not pass through capillary walls

Albumins(60%)

Part of plasma proteins

Produced by liver, transports steroids and fatty acids

Globulins(35%)

Part of plasma proteins

Antibodies(immunoglobulins), transport iron, lipids, fat soluble vitamins and hormones

Fibrinogen(4%)

Part of plasma proteins

Form clots with strands of fibrin

Regulatory(1%)

Part of plasma proteins

Enzymes, vitamins, hormones

Electrolytes

Other solutes

Vital for cell function, and osmotic pressure

Nutrients

other solutes

Products from digestion: protein(amino acids), carbs(glucose), lipids(fatty acids glycerides)

Waste products

Other solutes

Urea, uric acid, creatine, bilirubin, ammonia

Gases

Other solutes

O2, CO2, N2

All cells and solids,

45% of blood volume

Red blood cells(RBCs) or erythrocytes

Transport oxygen

White blood cells(WBCs) or leukocytes

Part of the immune system

Platelets

Cell fragments involved in clotting

Hematicrat

Equals the volume of blood that is RBC’s

Male: 40-54

Female: 36-46

Anemia

Decrease RBC

• low hematocrit

Polycythemia

Increased RBC high hematocrit→ tumor, dehydration, blood doping

RBC structure

• small and highly specialized disc

• Thin in middle and thicker at edge

• high surface-to-volume ratio quickly absorbs and releases oxygen

• Discs form stacks-smoothed flow through narrow blood vessels

• Discs bend and flex entering small capillaries

Hemopoiesis

Process of producing forced elements

Hemocytoblasts

Stem cells in bone marrow divide to produce myeloid and lymphoid

Myeloid

Stem cells become RBCs, some WBCs

Lymphoid

Stem cells become lymphocytes

Erythropoietin(EPO)

Hemopoietic growth factor

RBCs from kidney to red bone marrow

Thrombopoietin(TPO)

Hemopoietic growth factor

Platelets, from liver to red bone marrow

Cytokines(WBCs)

Hemopoietic growth factor

Colony-stimulating factors

Interleukins

Erythropoiesis

• red blood cell formation

• Occurs in only red bone marrow(myeloid tissue)

• Stem cells mature to become RBCs

• Myeloid stem cell→ proerythroblast→ erythroblasts→ reticulocyte→ mature RBC

Reticulocyte

Last step, 1%, 1-2 days to become RBC

Reticulocyte count

Measure rate of erythropoiesis

Dec=not replacing

Inc=recovering from loss

Hypoxia

Deficiency in cellular O2 will trigger erythropoiesis

Lifespan of RBC’s

Lack nuclei, mitochondria, and ribosomes

Live about 120 days, can’t repair itself, eventually burst

Spleen and liver

Lifespan of RBC’s

Where old RBCs are destroyed

Products recycled

Lifespan of RBC’s

Amino acids and iron

Transferrin

Lifespan of RBC’s

Transport form of iron

Ferritin

Lifespan of RBC’s

Storage form of iron(liver)

Ferrous

Lifespan of RBC’s

Absorbed form, aided by vitamin C, inhibited by alcohol

Bilirubin

Lifespan of RBC’s

Waste product from heme

Urbilinogen

Lifespan of RBC’s

Final end product(feces)

Urobilin

Lifespan of RBC’s

Final end product(urine)

Hemoglobin structure

• complex quaternary structure

• Protein molecule

• Transports recycling gases

• Recycling RBCs-1% of circulating RBCs wear out per day-about 3 million RBCs per second

• Macrophages of liver, spleen, and bone marrow-engulf RBCs before membranes rupture(hemolyze)

Hemoglobinuria

Diagnosing disorder

Hemoglobin breakdown products in urine due to excess hemolysis in blood stream

Hematuria

Diagnosing disorder

Whole red blood cells in urine due to kidney or tissue damage

Hemoglobin recycling

Phagocytes break hemoglobin into components

• globular proteins to amino acids

• Heme to biliverdin

• Iron

Iron recycling

To transport proteins(transferrin)

To store proteins(ferritin)

Breakdown of biliverdin

Biliverdin(green) is converted to bilirubin(yellow)

Bilirubin is excreted by liver(bile), jaundice is caused by bilirubin buildup, converted by intestinal bacteria to urobilins and stercobilins