CHAPTER 11: BLOOD11.1 Functions of Blood

Blood as the “essence of life” Noble “blue bloods” Anger causes blood to “boil” Fear causes blood to “curdle”

Blood Maintains Homeostasis:1. Transport of gases, nutrients, and waste products2. Transport of processes molecules3. Transport of regulatory molecules4. Regulation of pH and osmosis5. Maintenance of body temperature6. Protection against foreign substances7. Clot formation

11.2 Composition of Blood Blood – type of connective tissue

- Consists of a liquid matrix containing cells and cell fragments Plasma – liquid matrix (> ½ total blood volume) Formed elements – cells and cell fragments (slightly <½ total blood volume) Total Blood Volume (average adult)

- 4-5 L (females)- 5-6 L (males)

Blood: 8% of total body weight11.3 Plasma

Plasma – pale yellow fluid - 91% water- 7% proteins (dissolved)

58% Albumins Contributes to osmotic pressure (primary: sodium chloride) Water balance: determined by movement of water into and out of blood by osmosis Transport molecules (bind to molecules e.g. hormones)

38% Globulins Anitbodies and complement: part of the immune system Transport molecules (bind to molecules e.g. hormones) Clotting factors

4% Fibrinogen Clotting factor Converted to fibrin (threadlike protein that forms blood clots) Serum – plasma without the clotting factors

- 2% other components Ions Nutrients Waste products Regulatory substances

Plasma volume and composition remains relatively constant- Water intake (digestive tract) matches water loss (kidneys, lungs, digestive tract, skin)- Oxygen enters blood (lungs) and carbon dioxide enters blood (tissues)- Concentration of other suspended or dissolved substances maintained and regulated (liver, kidneys,

intestines, endocrine glands, immune tissues, lymph nodes, spleen)11.4 Formed Elements

95% Red Blood Cells (RBCs or erythrocytes)- 700 times more numerous than WBCs

- 17 times more numerous than platelets 5% White Blood Cells (WBCs or leukocytes) and Platelets (thrombocytes)

- 60%-70% Neutrophils- 20% - 25% Lymphocytes- 3% - 8% Monocytes- 2% - 4% Eosinophils- 0.5% - 1% Basophils

Production of Formed Elements Hematopoiesis – process of blood cell production

- Fetus: occurs in several tissues - After birth: confined primarily to red bone marrow- Some WBCs produced in lymphatic tissues

Stem Cells (hematocytoblasts) - Single population of cells from which all formed elements are derived - Differentiate to give rise to different cell lines- Cell line

Ends with formation of a particular formed element Development is regulated by specific growth factors

Determine types of formed elements derived from stem cells How many formed elements produced

Red Blood CellsFeatures: Disk-shaped Edges thicker than the center of the cell Biconcave shape – increases surface area

- Easier transport of gases - Easier bending or folding to fit within blood vessels

Development- Lose their nuclei and most of organelles- Consequently unable to divide

Live for about:- 120 days (males)- 110 days (females)

Hemoglobin - 1/3 of RBC volume- Responsible for red cell color

Function: Transport oxygen from the lungs to various tissues Transport carbon dioxide form tissues to the lungs

- Hemoglobin (4 protein chains, 4 heme groups)- Globin – each protein is bound to one heme- Heme – red-pigmented molecule; each contains one iron atom- Iron atom – bind to an oxygen molecule

*Hemoglobin picks up oxygen in lungs and releases it in other tissues *Hemoglobin bound to oxygen: bright red*Hemoglobin wihtout bound oxygen: darker red*2/3 of body’s iron found in hemoglobin

Responsible for 98.5% of oxygen transported in blood Remaining 1.5% is transported in dissolved plasma