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The Circulatory System:Blood
3 Functions of Blood
1. Transport – transports CO2 & O2
– Nutrients – metabolic waste (urea & lactic acid)– hormones– enzymes – plasma proteins
3 Functions of Blood
2. Regulation
•body temperature
•pH in body tissues
•fluid & electrolyte balance
3 Functions of Blood
3. Protection
•prevents excessive bleeding
•antibodies detect foreign material
•prevents infection (WBC)
Composition of Blood
• Blood – made of plasma and formed elements
• 8% of body wgt
• pH = 7.4
• 5x more viscous than water
Blood Composition Separated by Centrifugation
Hematocrit
Blood Plasma
plasma → nonliving fluid part; straw-colored•90% water; plasma proteins (8%)•Albumin –shuttles molecules through blood; buffer; helps maintain plasma’s osmotic pressure•Fibrogen – helps repair damaged tissue•Dissolved solutes (nutrients, gases, hormones, wastes, ions, proteins, etc.) (2%)•55% of blood volume
Blood Plasma
Formed Elements in Blood
Formed elements → living blood cells
-45% of blood
-platelets (thrombocytes) → clotting
-red blood cells (RBC; erythrocytes) →carry oxygen;
-white blood cells (WBC; leukocytes)
→fight infection
Blood cell formation
• Hematopoiesis (aka hemopoiesis)
• Occurs in:
• Red bone marrow stem cells»Vertebrate, ribs, hips, sternum, skull »Lymph tissue in nodes, tonsils,
spleen & thymus make small amounts
Erythrocytes (RBCs)• Plasma membrane; anucleate
• Hemoglobin- protein that transports oxygen/CO2
• Erythropoiesis• EPO
• Hemolysis – 120 days• Phagocytocis
Erythrocytes (RBCs)
Excessive RBC
• polycythemia – abnormal excess of erythrocytes that increases blood viscosity– Blood thickens, flows sluggishly
Leukocytes (WBCs)
• Complete cells (nuclei & organelles)
5 Types of WBC:Granulocytes – contain granulesTypes– neutrophils, basophils, & eosinophils
2. Agranulocytes – lack granulesTypes– lymphocytes and monocytes
Leukocytes (WBCs)
Platelets (Thrombocytes)
• Essential for clotting; occurs in plasma when blood vessels are ruptured or injured
• Form plug that helps seal break when they stick to damaged site
• Megakaryocytes in bone marrow
• Thrombopoietin
Platelets (Thrombocytes)
Coagulation (blood clotting)
• Hemostasis
• Procoagulants (clotting factors) – enhance clot formation
• Anticoagulants – factors that inhibit clotting; heparin
Hemostasis 4 phases:1.Constrict blood vessel; reduce blood loss2.Platelet plug hole & attract more platelets3.Platelet plug injury and coagulate; thrombin and fibrogen form fibrin mesh
- traps blood cells, seals hole until blood vessel can be fully repaired
3. Blood clot formation and retraction
Coagulation (blood clotting)
Blood Type
• antigen –chemical that stimulates cells to produce antibodies
• antibody –protein immune system produces in presence of nonself antigen; reacts with antigen– antibodies made limit receiving blood from
certain types– Rh factor: + or - Rh – exposure forms
antibodies to it
Blood Type Antigen AntibodyA A anti-B
B B anti-A
AB A and B *neither anti-A nor anti-B
O **neither Both anti-A A nor B and anti-B
*AB is universal recipient**O is universal donor
RBC Disorders
• anemia – blood has extremely low
oxygen-carrying capacity due to low number of RBCs, low hemoglobin content, or abnormal hemoglobin
Leukocyte Disorders
• leukemia – (“white blood”) = rapid, uncontrolled production of clones of cancerous leukocyte; impairs normal bone marrow function
Named after:– Abnormal cell type involved (i.e. lymphocytic
leukemia = lymphocytes)– Speed it advances:
acute – quickly advances (blast-type cells)
chronic – slowly advances (later cell stages)
Leukocyte Disorders
• Infectious mononucleosis – Epstein-Barr virus; makes excessive atypical agranulocytes– No cure; with rest, virus runs its course and
recovers in a few weeks