The Human Circulatory System and the Components of Blood

Circulatory System  The circulatory system is also referred to as the cardiovascular system  Functions very closely with digestive and respiratory systems  Basic system requires: 1. a pump (heart); 2. vessels/pathways (veins, arteries, capillaries); 3. fluid (blood).

Circulatory System Key Roles:  Maintains homeostasis body temperature regulation controls blood pressure  Delivers and removes substances throughout body DeliversRemoves - nutrients - oxygen - messages (via hormones) - toxins - metabolic wastes - carbon dioxide - toxins

Components of Blood  a sample of blood can be spun in a centrifuge high speed, circular motion causes blood to separate by the weights of its components

Components of Blood

Erythrocytes: Red Blood Cells  Produced in bone marrow, stored in spleen  Constantly destroyed and replaced  Distinct biconcave shape Flattened disc that is pinched in the centre Makes it flexible for traveling through various blood vessels  No nucleus  No mitochondria  Contains special hemoglobin molecule

 Complex protein made up of 4 protein chains, each with a central iron-containing heme group  Iron gives RBCs their distinct red colour  Iron binds with oxygen (4 O 2 molecules per hemoglobin molecule) – blood becomes oxygenated  Iron is recycled in bone marrow Hemoglobin

Anemia  Medical condition when there is a less than normal amount of hemoglobin in the blood  Less hemoglobin, less O 2 being delivered throughout the body  Can be caused by a genetic disorder (e.g., sickle cell anemia or thalassemias) or by a great loss of blood

Leucocytes: White Blood Cells  Produced in bone marrow  Larger than red blood cells, but much fewer in number  Amoeboid-shaped  Contain nucleus and lysosomes

 Part of body’s immune response system  Detects and defends body from infection and diseases Lysosomes digest foreign bacteria  Pus is formed at site of infection White blood cells (living & dead) + bacteria Body’s natural “soap”  An increase in WBCs indicate the body is fighting an infection  A problem with WBC overproduction could mean Leukemia Leucocytes: White Blood Cells

Platelets  Fragments of special cells from the bone marrow  Important for circulatory system repair  Form blood clots

Platelets – Blood Clotting  Detect damaged blood vessels  Burst and release special adhesive chemicals  Platelets stick together and form a platelet plug  Through chemical reactions, forms strand-like fibrin molecule  A mesh of fibrin strands forms a blood clot  Clot protects body from losing blood through the damaged vessel  Holds vessel wound together until it can be reconstructed with new tissue growth

Hemophilia  X-linked genetic disorder  Individual lacks special proteins that are needed for creating blood clots  Can bruise easily  Can bleed excessively if cut – sometimes bleeding to death

Shock  An actual medical condition – can be life- threatening  Body (or parts of body) shut down because circulatory system cannot meet oxygen demands of some vital organs  Body reduces blood flow to arms and legs so it can maximize O 2 getting to the vital organs (in body’s core)  Can result from loss of blood, extreme fright or emotional disturbance First Aid:  Put person in half upright position, keep warm  Apply direct pressure to any areas of severe bleeding  Get (call for) medical help