circulation

Blood

• 5 litres in the body
• -a specific type of tissue consisting of millions of cells in a fluid-
• jobs:
• to TRANSPORT SUBSTANCES around the body
• DEFEND body against infections and disease
• 

Plasma

• [90% H2O , 10% mixture - straw colour}
• Function:
• transports SOLUBLE SUBSTANCES
• carries CHEMICAL MESSENGERS (hormones)
• redistribute HEAT
• 

Platelets

• NO NUCLEUS - fragments of cells made in BONE MARROW
• [400,000 per Cm3 of blood]
• CLOTTS
• blood vessels are usually smooth- when cut they become rough; this causes a chemical to be released.
• FIBRINOGEN = soluble protein
• FIBRIN = insoluble protein
• ^
• fibrin - MESH where red blood cells and platelets are trapped
• 

Red Blood Cells

• [5,000,000 per CM3]
• Made in RED BONE MARROW
• live for 4 MONTHS - destroyed in LIVER SPLEEN
• red pigment - IRON
• no nucleus = Haemoglobin
• BICONCAVE shape = increased surface are
• Haemoglobin
• > a Protein
• > contains Iron = carries O2
• Haemoglobin + oxygen --------> oxyhaemoglobin
• CO poisoning
• Haemoglobin has a GREATER AFFINITY for CO than O2.
• breathed CO - less O2 binds with haemoglobin - tissues starve - no energy -death
• CO = Car exhausts fumes and cigarettes
• 

White Blood Cells Pt1

• - larger than red bloods cells
• - fewer of them [ 8,000 per CM3]
• function
• DEFEND against disease causing micro organisms called Pathogens.
• primary body defences ---> skin & openings secret defensive chemicals e.g.. mucus, HCl
• 2 types - Phagocytes & lymphocytes
• 

Phagocytes

• - made in RED BONE MARROW
• - Live for a FEW DAYS
• Large & irregular shapes
• MULTILOBED NUCLEUS & GRANULATED CYTOPLASM
• Function:
• TO DESTROY = Engulf & DIGEST = PHAGOCYTOSIS
• 

Lymphocytes

• - made in the LYMPHATIC SYSTEM
• - Live for SEVERAL YEARS
• SPHERICAL shape & Red Blood Cell size
• LARGE NUCLEUS, Small NON-GRANUAL CYTOPLASM
• Function:
• produce ANTIBODIES
• ANTIBODIES
• target surface of proteins called ANTIGENS
• then tell lymphocytes to produce more anitbodies
• cause Micro organisms to CLUMP TOGETHER
• PROMOTES phagocytosis
• prevents Antigens INVADING HOST CELL
• tagets toxins with ANTI-TOXINS
• 

Diapositiva 8