THE MAMMALIAN CIRCULATORY SYSTEM SBI3C

Main Parts of the System Heart (the pump) Vessels (tubes) Blood (transport fluid)

An Efficient System Blood travels within vessels at all times Efficient transport of materials to and from cells of body 3 circulatory pathways - systemic pathway (to & from body’s organs) - pulmonary pathway (to & from lungs) - cardiac pathway (to & from heart muscle)

General Functions Transport - oxygen to body cells - carbon dioxide to lungs - nutrients to body cells (sugars, amino acids, vitamins, etc) - hormones (e.g. insulin) - wastes to kidneys (urea) Defense against foreign invaders (e.g. bacteria, viruses) Repair to blood vessels (clotting) Body temperature regulation Maintenance of water levels in body

The Blood The red, opaque whole blood of mammals consists of 4 components – Red blood cells White blood cells Platelets Plasma

Blood Parts Whole blood can be separated into 3 layers by centrifugation (spinning it at high speeds)

Red Blood Cells also called RBC’s or erythrocytes Biconcave shape Lack a nucleus Iron-containing, red protein, hemoglobin Carry the majority of oxygen as oxyhemoglobin to cells from lungs Carry the majority of carbon dioxide as bicarbonate ions (HCO 3 - ) from cells to lungs

White Blood Cells Also called WBC’s or leucocytes WBC’s defend body against bacteria & viruses Macrophages, produced in bone marrow, destroy by phagocytosis Lymphocytes, produced in lymph tissue (glands, tonsils, adenoids), destroy by producing antibodies and toxic chemicals

Platelets Also called thrombocytes Gather at site of damaged blood cells React with plasma factors to form a temporary clot (thrombus) to stop leakage of blood from vessel

Plasma A clear, straw-coloured liquid 91% water 55% of blood Transports - some O 2 and CO 2 - nutrients and wastes - hormones - clotting factors - blood cells and platelets - water balance chemicals - heat to keep body warm & cool

The Blood Vessels Blood vessels create a continuous pathway to and from heart 3 main types of blood vessels - arteries - veins - capillaries All arteries carry blood away from heart All veins carry blood towards the heart Capillaries connect arteries to veins

Comparing Circulatory Pathways Mammalian system uses a double pump (heart) and keeps oxygenated blood separate from deoxygenated blood

Arteries Large, muscular thick-walled vessels with a small inner diameter Carry mainly oxygenated blood under high pressure from heart to body* *Exception – pulmonary arteries deliver deO 2 blood from heart to lungs Disorder – aneurysm

Veins Large, thin-walled vessels with a large inner diameter Contain one-way valves Carry mainly deoxygenated blood under low pressure from body to heart* Skeletal muscle contractions return blood to heart *Exception – pulmonary veins return O 2 blood from lungs to heart Disorder – varicose veins

Major Arteries & Veins Associated with heart, lungs and abdominal cavity renal artery renal vein

Capillaries Microscopic, one-cell thick vessels Inner diameter less than 7  m Carry blood cells under low pressure in single file for O 2 -CO 2 exchange and nutrient-waste exchange Plasma and WBC’s able to squeeze out of capillaries at organs

The End