Anatomy & Physiology Chapter 17 Blood

functions of blood

-transportation of dissolved gases, nutrients, hormones, and metabolic wastes

-regulation of pH and ion composition in interstitial fluids

-restriction of fluid losses at injury sites

-defense against toxins and pathogens

-stabilization of body temperature

plasma

92% water, 7% plasma proteins, and 1% other solutes, 46-63% of the volume of whole blood

properties of blood

-38 degrees C, 100.4 degrees F, five times as viscous as water, and slightly alkaline, with a pH between 7.35 and 7.45

hematocrit

percentage of whole blood volume contributed by formed elements, mostly red blood cells

PCV

normal hematocrit, 47 for adult males and 42 for adult women

formed elements

cells in the blood, 99.9% RBCs, <.1% WBCs, <.1% platelets

albumins

osmotic pressure in plasma, 60% of plasma proteins

globulins

antibodies and transport globulins, 35% of plasma proteins

fibrinogen

functions in clotting and interacts to form fibrin for blood clots, 4% of plasma proteins

electrolytes

sodium, potassium, calcium, magnesium, chloride, and other acids

organic nutrients

lipids (fatty acids, cholesterol, and glycerides), carbohydrates (glucose), and amino acids, used for ATP production, growth, and maintenance

organic wastes

urea, uric acid, creatinine, bilirubin, and ammonium

platelets

small, membrane-bound cell fragments that contain enzymes and other substances important in clotting

WBCs

leukocytes, participate in the body's defense mechanism

RBCs

erythrocytes, essential for transport of oxygen

red blood cell count

number of RBCs per microliter of blood, 4.5-6.3 million in adult males, 4.2-5.5 million in adult females

hemoglobin (Hb)

14-18 g/dL in males and 12-16/dL in females

heme

non-protein pigment complex in each Hb chain

oxyhemoglobin

when the iron on the heme interacts with an oxygen molecule

what happens to RBCs?

They have a lifespan of 120 days and then get engulfed by macrophages in the liver, spleen, or bone marrow

proerythroblasts

cells destined to become RBCs

erythroblasts

various stages, synthesize hemoglobin

reticulocyte

after 4 days of differentiation, the normoblast sheds its nucleus and becomes this, containing 80% of the Hb of a mature RBC

erythropoiesis

blood cell formation, occurs in red bone marrow, or myeloid tissue

antigens

substances that can trigger a protective defense mechanism called an immune response

surface antigens

substances on the plasma membranes of our blood cells that our immune system sees as normal

blood type

a classification determined by a specific surface antigens in RBC plasma membranes

type A blood

surface antigen A, anti-B antibodies

type B blood

surface antigen B, anti-A antibodies

type AB blood

both A and B surface antigens, neither anti-A or anti-B antibodies

type O blood

neither A nor B surface antigens, both anti-A and anti-B antibodies

agglutinate

clumping together that occurs when one blood type is exposed to the corresponding antibodies from another blood type, agglutination

Rh positive

indicates the presence of the Rh surface antigen, also called D antigen

properties of WBCs

-are only in the blood stream when they need to get to an area of injury

-emigration or diapedesis, sticking to the blood vessel walls and squeezing between the endothelial cells to enter the surrounding tissue

-respond to chemical stimuli, positive chemotaxis

-some are capable of phagocytosis

granular leukocytes

abundant cytoplasmic granules, neutrophils, eosinophils, and basophils

agranular leukocytes

few, if any, cytoplasmic granules: monocytes and lymphocytes

neutrophils

-50-70%

-phagocytic, engulf pathogens or debris, release cytotoxic enzymes and chemicals

eosinophils

-2-4%

-phagocytic, engulf antibody-labeled materials, reduce inflammation, act in asthma and allergic reactions

basophils

-<1%

-enter damaged tissues and release histamines and other chemicals that promote inflammation

monocytes

-2-8%

-enter tissues and become macrophages, engulf pathogens and debris

lymphocytes

-20-30%

-provide defense against specific pathogens or toxins

hemocytoblasts

stem cells in red bone marrow, give rise to lymphoid stem cells and myeloid stem cells, responsible for producing all formed elements

megakaryocytes

enormous cells with large nuclei, make proteins, enzymes, and membranes before shedding cytoplasm in packets that become platelets in the bloodstream

erythropoietin

released into the plasma when peripheral tissues are exposed to low oxygen concentrations, (1) during anemia, (2) when blood flow to the kidneys declines, (3) when the oxygen content of air in the lung declines, and (4) when the respiratory surfaces of the lungs are damaged, stimulates stem cells and developing RBCs

hemostasis

a process responsible for stopping the loss of blood through the walls of damaged vessels

vascular phase

-endothelial cells contract and expose the underlying basal lamina

-endothelialcells release chemical factors and hormones that cause the smooth muscles to contract

-endothelial plasma membranes become sticky, to stop blood flow and facilitate the attachment of platelets

platelet phase

attachment of platelets to sticky endothial surfaces, the basal lamina, exposed collagen surfaces, and each other

coagulation phase

the conversion of circulating fibrinogen to the insoluble protein fibrin