Introduction

 The cardiovascular system is like the coolingsystem of a car.

Includes blood, the heart, and a network of blood vessels

Provides a mechanism for the rapid transport of nutrients, waste products, and cells within the body

Functions of the Blood

 Blood is a specialized fluid connective tissue that

Distributes nutrients, oxygen, and hormones

Carries metabolic wastes to the kidneys

Transports white blood cells

Maintains homeostasis

Composition of the Blood

Whole blood consists of two components:

Plasma — the liquid matrix; contains dissolved proteins

Serum

Formed elements — blood cells and cell fragments suspended in the plasma

RBCs transport oxygen and carbon dioxide
WBCs support the immune system
Platelets aid in blood clotting

5–6 liters of blood in an adult man

 4–5 liters in an adult woman

 Blood volume

Hypovolemic = low

Normovolemic = normal

Hypervolemic = high

 Alkaline pH (range of 7.35 to 7.45)

 Temperature = 100.4°F

Plasma

Resembles interstitial fluid but:

The concentrations of dissolved oxygen and carbon dioxide are higher, and
It contains significant quantities of dissolved proteins.

Approximately 7% of plasma is made up of proteins.

Three major classes of plasma proteins:

Albumins
Globulins
Fibrinogen

Formed Elements

Red blood cells (RBC) or erythrocytes

Most numerous cell

Transports oxygen and carbon dioxide

Usually degenerate after roughly 120 days in circulation

Hemoglobin (Hb)

Accounts for more than 95% of the RBC’s proteins
Give RBCs the ability to transport oxygen and carbon dioxide

White blood cells (WBC) or leukocytes

Defend body against pathogens and remove toxins, wastes, and abnormal or damaged cells

Two classes:

Granular leukocytes
Neutrophils
Eosinophils (acidophils)
Basophils
Agranular leukocytes
Monocytes
Lymphocytes

Show chemotaxis (the attraction to specific chemicals) and diapedesis (the ability to move through vessel walls)

Platelets

Not cells; they are membrane-enclosed packets of cytoplasm

Released into blood by megakaryocytes, enormous cells in the bone marrow

Circulate for 10 —12 days before being removed by phagocytes; continually replaced

Functions

Transport chemicals important for clotting
Temporarily patch the walls of damaged blood vessels

Causing contraction after a clot has formed to reduce the size of the break in the vessel wall

Hemopoiesis

 The process of blood cell formation

 Stem cells or pluripotential stem cells (PPSC) divide to form all of the blood cells.

Give rise to myeloid stem cells and lymphoid stem cells

 Original blood cells form in developing bloodvessels.

Spleen and liver contribute in fetal blood cell development

Red bone marrow takes over in postnatal life