Blood & Bodily Fluids

Functions of Blood

Distribution of nutrients, transport of oxygen, carbon dioxide, waste products, and hormones, assistance in body temperature control, assistance in maintaining pH by providing chemical buffers, assistance with the prevention of blood loss by providing proteins and other factors for blood coagulation, and assistance with defense of the body against disease by providing antibodies, cells, and other factors

What does blood consist of?

It consists of cells and other cell-like formed elements suspended in plasma

Plasma vs. Interstitial Fluid

Plasma has a higher concentration of proteins that cannot easily diffuse through capillary walls

Elements of Blood (3)

Erythrocytes, leukocytes, and platelets

Hematopoiesis

Formation and development of all formed elements of blood, all share pluripotent stem cell as a common ancestor

Where do blood cells come from?

Blood cells proliferate and differentiate from bone marrow stem cells

Hematopoietin

A variety of circulating chemical messengers that help regulate proliferation and differentiation of bone marrow stem cells (highly regulated process)

Erythrocytes

Red blood cells, biconcave disks with a thick circular margin and a thin center, have no nuclei and few organelles, most domesticated animals have 7 million red blood cells per microliter of whole blood, are degraded in the reticuloendothelial system which is important to prevent toxic buildup

Hemoglobin

Major intracellular constituent of erythrocytes, thing that makes blood red, has 4 amino acid chains held together by noncovalent interactions, oxygen and carbon dioxide bind to the hemoglobin for transport (this is a reversible process)

Erythropoiesis

Erythrocyte formation, regulated by erythropoietin which responds to reduced oxygen delivery

Hematocrit

% by volume of whole blood that is erythrocytes

Platelets

Also called thrombocytes, surrounded by a plasma membrane, have no nuclei but some organelles, reduce the loss of blood from injured vessels by clotting, low platelets = internal bleeding

Leukocytes

White blood cells, nucleated, capable of independent movement to exit blood vessels, responsible for protecting the body from infection and disease

Granulocytes

Subclassification of white blod cells, have granules, neutrophils, eosinophils, and basophils

Agranulocytes

Subclassification of white blood cells, do not have granules, monocytes and lymphocytes

Plasma

Fluid portion of the blood, mainly made of water, kidneys maintain plasma, derived by centrifugation of blood

What are the 2 predominant particles in plasma?

Na+ and chloride ions

What are the 2 major types of plasma proteins?

Albumin (most prevalent) and globulins

Serum

Plasma without any clotting proteins (made by letting blood sit and letting the clotting proteins clot and settle to the bottom)

Hemostasis

The stoppage of bleeding

3 Reactions to Stop Bleeding

1. Constriction by smooth muscle of injured vessel to decrease the size of the opening and increase resistance to flow out of the vessel

2. Formation of a platelet plug to occlude the opening

3. Clot formation to complete occlusion of the opening (this step is not always necessary)

Lymph

Fluid/protein that is lost from capillaries and flows through the lymphatic system

Lymphatic System

Comrpised of lymph vessels and intervening lymph nodes whose function is to return fluid from tissues back to central circulation

Where does lymph return to the blood?

It returns to the blood when the largest of the lymphatic vessels joins with large veins cranial to the heart

Edema

An abnormal accumulation of fluid within the interstitial space, can be a result of blocked lymphatic vessels

Serous Fluids

Fluids in body cavities that create a thin film that reduces friction between apposed surfaces, does not contain any significant cellular content