Blood

Composition: It is composed of liquid plasma and formed elements:

• Erythrocytes- RBCs-red blood cells, they do not have a nucleus.
• Leukocytes- WBCs-white blood cells. They are the only formed element that is a complete cell.
• Plateletes-broken up peices of cells that help with blood clotting.

Blood Stats

• Hematocrit-a measure of the amount of red blood cells in your blood.
• Blood is 8% of your total body weight.
• Normal pH is 7.35-7.45
• Normal temperature-38 degrees Celsius
• Men have a typical blood volume of 5-6 L.
• Women have a typical blood volume of 4-5 L.
• Oxygen rich blood is scarlet red (bright!)
• Oxygen poor blood is dark red (i.e. bluish, venous blood)
• Blood is the only fluid tissue in your body!

Functions of Blood

1. Protection-i.e. clotting, immune system.
2. Transport-oxygen, carbon dioxide, nutrients, waste, and hormones to their target cells.
3. Homeostasis-water volume, sugar, Ca, pH, body temp., vasoconstriction and vasodialation. Blood is a good buffer.

Blood Plasma

Plasma contains over 100 solutes!

• Proteins-i.e. albumin, clotting proteins, and globulins.
• Nonprotein Nitrogenous Substances-i.e. creatinine, lactic acid, and urea.
• Organic Nutrients-i.e. glucose, carbohydrates, and amino acids.
• Electrolytes (charged particles)-i.e. Na, K, and Ca ions.
• Respiratory Gases-i.e oxygen and carbon dioxide.

Erythrocytes (Red Blood Cells-RBCs)

• Erythrocytes have a high surface area to volume ratio.
• They are flattened in the middle because they don't have a nucleus.
• An erythrocyte-water is 97% hemoglobin, which carries oxygen.
• Most RBCs only live a few days, but they can live up to 120 days.

Erythropoiesis-Making Erythrocytes

1. The undifferentiated stem cell is called a hemocytoblast.
2. This cell then becomes a committed cell, known as a proerythroblast.
3. Phase 1-Ribosome Synthesis
4. Phase 2-Hemoglobin accumulation (nomoblast)
5. Phase 3- Ejection of the nucleus (reticulocyte)

• This makes an: ERYTHROCYTE!

Hemostasis

Hemostasis-is the stopping of blood.

It occurs in three phases:

1. Vascular Spasms
2. Platelet plug formation
3. Coagulation