Chapter 11 - The Cardiovascular System

functions of blood

transport of gases, nutrients, hormones, wastes, clotting, defense against infection, temperature regulation

blood consists of plasma and formed elements

plasma (55%) of total volume (water (92%), proteins (7%), other solutes (1%, nutrients, ions, wastes))

Formed elements

45% of total volume of blood (red blood cells - 99.9% (carry oxygen), white blood cells - <0.1% (fight infection), platelets <0.1% (clotting))

red blood cells

function to carry oxygen, large surface area allows rapid diffusion of oxygen in/out of cell, lack nucleus and mitochondria

hemoglobin

responsible for O2 transport, 95% are intracellular proteins, has four subunit molecules called heme (each heme holds an iron subunit that allows for bonding with oxygen, giving blood it’s bright red color)

erythropoiesis

RBC formation is a homeostatic mechanism, oxygen levels must be maintained, kidney detects low oxygen levels, secretes EPO

blood cell development

multiple pathways form a single stem cell, cells lose ability to divide as they mature, leukemia is a defect in this process (many dividing, immature WBCs)

type A blood

has RBC’s with surface antigen A only

type B blood

has RBC’s with surface antigen B only

type AB blood

has RBC’s with both A and B surface antigens (universal recipient)

type O blood

type O blood has RBC’s lacking both A and B surface antigens (universal donor)

Rh blood types (Rhesus factor)

separate antigen from the ABO blood antigens, can be positive or negative

white blood cells have several types

Neutrophils

Eosinophils

Basophils

Monocytes

Lymphocytes

neutrophils

most common, attack bacteria

eosinophils

attack parasites, antibody-coated pathogens

basophils

rare, induce inflammation by secreting histamine

monocytes

move into tissues, become macrophages

lymphocytes

specific immunity, T cells attack infected or cancer cells, B cells secrete antibodies

diapedesis

WBC’s can leave the bloodstream and enter tissues by this process in order to attack their targets

hemostasis has 3 phases

vascular phase, platelet phase, coagulation phase

vascular phase

tissue damage causes vascular spasm in blood vessel wall, limits blood loss, endothelium becomes sticky

platelet phase

platelets attach to sticky tissue, form temporary clot

coagulation phase

clotting factors released by platelets and damaged tissues cause conversion of fibrinogen to fibrin, this process is inhibited by Coumadin, a “blood thinner”

plasmin

dissolves clots, causes clot retraction and used to treat stroke

vitamin K

required for the production of 4 clotting factors