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