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Functions of the Circulatory System - DOC

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					Biology: Study Notes # 4= Circulatory System                        Name_______________________________
                                                                    Date_____________________Per.________
Functions of the Circulatory System
1. Transport of…
  Respiratory gases
  Nutrients
  Wastes
  Hormones
2. Defense from…invaders and blood loss

Blood vessels:
1. Arteries= Carry blood away from heart; they are thick and
muscular: under pressure
2. Veins= Carry blood toward the heart. They are Thin, little
muscle containing valves
3.Capillaries= are the Smallest, one cell thick & diameter. They
bring nutrients and oxygen to the cells and absorb carbon dioxide
and other wastes. This is where exchanges occur
Blood components: Blood is a type of connective tissue containing dissolved substances and specialized cells. Blood is
almost half cells and half fluid. The fluid portion of blood is called PLASMA. Cells are RBC, WBC, and platelets.
 a. Plasma= Yellow liquid (90% water) Transports:Food, Wastes, Hormones, Fibers, proteins (clot & fighting infection)
 b. Blood components =Red blood cells(erythrocytes) Small, biconcave cells without nucleus Hemoglobin (red pigment),
     gives ability to…Transport oxygen
     White blood cells (leucocytes)Large, clear, ameboid, cells with nucleus & granules; Fight infection (by phagocytosis)
     Platelets (thrombocytes) Smallest; cell fragments For clotting only
Heart
   Pericardium sac surrounding heart, to prevent friction
 The heart is divided into right and left halves by a wall called the septum.
 Each half of heart has 2 Chambers (4 total):
          o Atria (Atrium) (right & left) = receive blood
          o Ventricles (right & left) =pump blood
 Valves = prevent backflow of blood
       Between atria & ventricles
       Between ventricles & arteries
PATH OF BLOOD:
Step by Step…
•   All of the veins come & empty into : #1 Right Atrium
•   Blood then flows into:# 2 Right Ventricle
•   Right Ventricle sends this O2 poor blood to lungs to exchange gases.
•   Then blood returns to: # 3 Left Atrium
•   Blood then flows to: # 4 Left Ventricle
•   The Left Ventricle is important because it ultimately pumps blood to all of the body.

Lymphatic System
Lymphatic System Function: Series of vessels that collect fluids lost by blood & returns blood to circulatory system
Main organs: thymus, spleen. lymph nodes, lymph vessels (Ex. Tonsils)
Works in conjunction with the immune system
Lymph Organs Primary function: to trap and filter microorganisms that may have invaded the body (May become
enlarged when many microbes are trapped, indicating illness)

				
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