Bell Work

1. How would you describe blood?2. Does lower or higher density materials float?3. What does proximal mean?4. Where is the epiphysis of the femur located?5. What is a clot?6. What is blood plasma?

Blood

• The only fluid tissue in our body• It transports everything that is needed in our

bodies• It has formed elements (living blood cells) and

plasma (nonliving fluid matrix)

Hematopoiesis

• Blood Cell Formation• Occurs in the Red Bone Marrow or myeloid

found chiefly in the flat bones of the skull and pelvis, the ribs, sternum, and the proximal epiphyses of the humerus and femur.

• All blood cells arise from a common type of stem cell called the hemocytoblast, but triggers will cause the stem cells to irreversibly change to produce the different types of blood cells

Figure 10.4 from page 335

Separating Blood

• Blood can be separated using a centrifuge, which uses a fast rotational motion to separate components based on densities.

• Materials with high densities would sink to the bottom while lower densities would remain at the top.

At the top, you would have…

• Plasma, which is composed of– Mostly water (90%)– Salts– Plama Proteins– Nutrients– Waste– Respiratory Gases– Hormones

At the bottom, you would have…

Erythrocytes

Erythrocytes

• Red blood cells• Outnumber other parts by roughly 1000 to 1 • Transport oxygen and carbon dioxide• They do not have a nucleus and have very few

organelles• Basically, they are a sac full of the iron-bearing

protein called hemoglobin• One cell can contain 250 hemoglobin molecules,

each of which can bind 4 oxygen molecules

In the middle, the buffy coat, which contains…

LeukocytesPlatelets

Leukocytes• White blood cells • Defense and immunity• Can perform –Diapedesis – can leave and enter the blood

stream–Positive chemotaxis – they can travel around the

body in response to chemicals that are released from damaged cells. They follow the diffusion gradient of these chemicals to find the injured area.– Leukocytosis – when the body makes more WBC– Leukopenia – abnormally low levels of WBC

Types• Granulocytes – contain granules– Neutrophils –phagocytes at sites of acute infection– Eosinophils – helps battle allergies and infections by

parasitic worms– Basophils – contain large histomine (inflammatory

chemical) containing granules• Agranulocytes– Lymphocytes – Found in lymphatic tissue and plays an

important role in immune response– Monocytes – Largest WBC that migrates into tissues,

turn into macrophages, which can destroy large amounts of infection.

Platelets

• Irregular cell fragments that originate from megakaryocytes

• Used for blood clotting when hemostasis occurs

What is hemostasis?

• A stoppage of blood flow through broken blood vessels

• Steps in hemostasis.1. Platelet plug formation – “sticky” platelets cling to

damage area and use a chemical to attract more platelets

2. Vascular spasms – serotonin is also released by platelets. This causes the blood vessel to spasm and narrow, which decreases blood loss

3. Coagulation (blood clotting) occurs

Coagulation Steps1. Injured tissue releases tissue factor2. A chemical, PF3, on the surface of the platelets

reacts with the tissue factor and some other ions to form an activator (prothrombin) that starts the clotting cascade.

3. The activator converts prothrombin into thrombin4. The thrombin joins fibrinogen in the area into long,

insoluble, hair like molecules called fibrin. This creates a mesh that traps RBC and forms the clot.

5. Once the clotting cascade starts, factors are triggered to stop widespread clotting