Chapter 18: The Circulatory System: Blood

transport (blood fn)

O2, CO2, nutrients, wastes, hormones, and stem cells

protection (blood fn)

inflammation, limit spread of infection, destroy microorganisms and cancer cells, neutralize toxins, and initiate clotting

regulation (blood fn)

fluid balance, stabilizes pH of ECF, and temperature control

hematology

the study of blood

4-6 liters

Roughly how much blood do adults have?

blood

a liquid connective tissue consisting of cells and extracellular matrix

plasma

liquid/matrix of blood

• clear, light yellow fluid

formed elements

blood cells and cell fragments

• RBCs, WBCs, and platlets

erythrocytes

heaviest and settle first in centrifuge

• 37-52% total volume

buffy coat

White blood cells and platelets

• <1% of blood volume

plasma

47-63% of blood volume

platelets

cell fragments from megakaryocyte in bone marrow

granulocytes (3)

• neutrophils

• eosinophils

• basophils

agranulocytes (2)

• lymphocytes

• monocytes

serum

remaining fluid when blood clots and solids are removed

albumins (plasma protein)

smallest and most abundant

• contribute to viscosity and osmolarity

• first to appear if damage to membrane

• responsible for colloid osmotic pressure

globulins (plasma protein)

• provide immune system functions

• alpha, beta, and gamma globulins

fibrinogen (plasma protein)

precursor of fibrin threads (blood clot)

liver

forms plasma proteins (except immunoglobulins)

nitrogenous compounds

• free amino acids from dietary protein or tissue breakdown

nitrogenous wastes

• toxic end products of catabolism

• normally removed by the kidneys

electrolytes

Na⁺ makes up 90% of plasma cations

viscosity

resistance of a fluid to flow, resulting from the cohesion of its particles

heart does more work

higher viscosity

4.5 to 5.5 times

how much more viscous is whole blood than water

2.0 times

how much more viscous is plasma than water

osmolarity of blood

the total molarity of those dissolved particles that cannot pass through the blood vessel wall

osmolarity of blood too high

blood absorbs too much water, increasing the blood pressure

osmolarity of blood too low

water stays in tissue, blood pressure drops, edema occurs

hypoproteinemia

deficiency of plasma proteins

• extreme starvation

• liver or kidney disease

• severe burns (fluid loss, lose plasma)

Kwashiorkor

children with severe protein deficiency

• thin arms and legs

• swollen abdomen

Hemopoiesis

production of blood, especially its formed elements

yolk sac

produces stem cells for first blood cells

• colonize fetal bone marrow, liver, spleen, and thymus

at birth

When does the liver stop producing blood cells?

spleen

involved with lymphocyte production

pluripotent stem cells (PPSC)

formerly called hemocytoblasts or hemopoietic stem cells

colony forming unit

specialized stem cells only producing one class of formed element of blood

• give rise to a specific category of cells (ex: platelet)

myeloid hemopoiesis

blood formation in the bone marrow

lymphoid hemopoiesis

blood formation in the lymphatic organs (beyond infancy this only involves lymphocytes)

functions of erythrocytes

• carry oxygen from lungs to cell tissues

• pick up CO2 from tissues and bring to lungs

mitochondria and nucleus (DNA)

which two organelles do erythrocytes lack?

hemoglobin (Hb)

four protein chains → globins

four heme groups

adult hemoglobin (Hb)

contains two alpha and two beta chains

fetal hemoglobin (Hb)

contains two alpha and two gamma chains

heme groups

non protein moiety (component) that binds O2 to ferrous ion (Fe) at its center

oxyhemoglobin

oxygen binds to heme

saturated hemoglobin

all four O2 molecules bound to heme groups

unsaturated hemoglobin

less than four or zero O2 molecules bound to heme groups

carbaminohemoglobin

CO2 binds to heme

carboxyhemoglobin

CO binds to heme

RBC count and hemoglobin concentrations

what indicates the amount of O2 blood can carry

hematocrit (packed cell volume)

percentage of whole blood volume composed of RBCs

RBC count in men

4.6-6.2 million/uL

RBC count in women

4.2-5.4 million/uL

erythrocytosis

more than normal amount of RBCs

Erythrocytopenia

not enough RBCs

Hypoxia

lack of O2, less O2 travels to tissues

• result from erythrocytosis

erythropoiesis

RBC production

• 1 million per second

120 days

lifespan of RBCs

3-5 days

development time for RBCs

reticulocytes

• 0.5 - 1.5% of circulating RBCs are this

• named for fine network of endoplasmic reticulum

• count is used to gauge bone marrow activity

macrophages in spleen

• digest membrane bits

• separate heme and globin

  • globins hydrolyzed into amino acids

• iron removed from heme

polycythemia

an excess of RBCs, increased # of formed elements

Primary polycythemia (polycythemia vera)

cancer of erythropoietic cell line in red bone marrow

secondary polycythemia

from dehydration, emphysema, high altitude, or physical conditioning

causes for anemia

• inadequate erythropoiesis or hemoglobin synthesis

• hemorrhagic anemias from bleeding

• hemolytic anemias from RBC destruction

agglutination

clumping of RBCs

• rxn between RBCs and antibodies in plasma

agglutinogens

RBC antigens

• antigen A and B

• determined by glycolipids on RBC surface

agglutinins

antibodies found in plasma

• Anti-A and anti-B

Type O

Universal donor (blood type)

leukocytopenia

< 5,000 WBC/uL

leukocytosis

> 10,000 WBC/uL

granulocytes

neutrophils, eosinophils, basophils

Neutrophils

• most abundant (60%-70%)

• polymorphonuclear leukocytes

• barely visible granules in cytoplasm; 3-5 lobed nucleus

• red and blue staining

Eosinophils

• 2%-4%

• large rosy-orange granules; bilobed nucleus

• red staining

Basophils

• less abundant (less than 1%)

• large, abundant, violet granules (obscure a large S-shaped nucleus)

• blue staining

Agranulocytes

• lymphocytes and monocytes

• vesicles don’t stain (granules are still present)

Lymphocytes

• 25%-33%

• variable amounts of bluish cytoplasm (scantly to abundant)

• ovoid/round; uniform dark violet nucleus

Monocytes

• 3%-8%

• usually largest WBC; ovoid, kidney-, or horseshoe-shaped nucleus

neutrophils

aggressively antibacterial

neutrophilia

rise in number of neutrophils in response to bacterial infection

Eosinophils

elevated number of cells fights off parasitic infections, collagen decreases, allergies, disease of spleen and CNS

Basophils

increased numbers in allergies

• secrete histamine

• secrete heparin

histamine

• vasodilator

• speeds flow of blood to an injured area

heparin

• anticoagulant

• promotes the mobility of other WBCs in the area

mast cells

• basophil’s sister cell

• part of epithelium and tissue structures (ex: respiratory)

lymphocytes

increased numbers in diverse infections and immune responses

• destroy cells

• “present” antigens to activate other immune cells

• coordinate actions of other immune cells

• secrete antibodies and provide immune memory

T cells

cell mediated immunity

B cells

antibody mediated immunity

K cells

immunological surveillance

monocytes

increased numbers in chronic infections and inflammation

• leave bloodstream and transform into macrophages

leukemia

cancer of hemopoietic tissue usually producing a very high number of circulating leukocytes

myeloid leukemia

uncontrolled granulocyte production

lymphoid leukemia

uncontrolled lymphocyte or monocyte production

acute leukemia

appears suddenly, progresses rapidly, death within months

chronic leukemia

undetected for months, survival time 3 years

hemostasis

the cessation of bleeding

• stopping potentially fatal leaks

hemorrhage

excessive bleeding

hemostatic mechanisms (fastest to slowest)

• vascular spasm

• platelet plug formation

• blood clotting (coagulation)

platelets

• small fragments of megakarocyte cells

• 2-4 um diameter; contains “granules”

• contains a complex internal structure and an open canalicular system

• amoeboid movement and phagocytosis