Blood Composition and Function
Blood - The River of Life
· connective tissue
formed elements - living blood cells
plasma - non-living fluid matrix
dissolved fibrous proteins (responsible
for blood clotting)
Blood Composition & Function · blood sample
top - plasma (55%)
middle - buffy coat (white blood cells and platelets)
bottom - erythrocytes, or hematocrit (45%)
· metallic, salty taste
· pH 7.35 to 7.45 (slightly alkaline)
· 38 C or 100.4 F (slightly warmer than body temp)
· accounts for 8% of our body weight
· average volume
males - 5-6 L (about 1.5 gallons)
females - 4-5 L
Blood Functions Blood Plasma
· DISTRIBUTION · straw-colored, sticky fluid
1. deliver oxygen from lungs and nutrients from · about 90% water
digestive tract to all body cells · 8% plasma proteins
2. transport metabolic waste products from cells to albumin (60%) - transports
elimination sites (lungs, kidneys) molecules, blood buffer,
3. transport hormones from glands to target organs contributes to plasma osmotic
· REGULATION pressure (keeping water in
4. maintain appropriate body temperature blood)
5. maintain normal pH in body tissues globulin (36%) - transports
6. maintain adequate fluid volume in circulatory molecules (alpha and beta),
system antibodies (gamma)
fibrinogen (4%) - blood clotting
· PROTECTION
· 2 % other
7. prevent blood loss (clotting)
nutrients, electrolytes, respiratory
8. prevent infection (antibodies, complement gases, hormones
proteins, white blood cells)
Formed Elements Erythrocytes - RBC
· produced in red bone marrow
platelets · small, biconcave discs
erythrocytes cell · mature RBCs lack a nucleus
red blood cell fragments · contains hemoglobin (gas transport)
(RBC) oxygen-rich - scarlet
oxygen-poor - dark red
· structure supports their function
1. small size and biconcave shape increase
surface area
leukocytes 2. 97% hemoglobin
white blood cell
3. generate ATP through anaerobic
(WBC)
respiration, so they do not consume the
oxygen they carry
· live about 120 days before destroyed
· 4.3-5.8 million per microliter
Blood Composition and Function
Erythrocyte Function Hematopoiesis
· gas (O2 and CO2) transport · blood cell formation
· hemoglobin binds easily and reversibly with O2 · occurs in red bone marrow
globin - protein containing 4 polypeptide chains · hemocytoblasts (blood cell builders) - stem cells
heme - red pigment containing an iron atom that differentiate into myeloid and lymphoid cells
found in each polypeptide chain
myeloid - RBCs, platelets, basophils, eosinophils,
· each hemoglobin can carry 4 O2 atoms
monocytes, and neutrophils
· each RBC contains 250 million hemoglobin molecules
lymphoid - lymphocytes
can carry 1 BILLION oxygen atoms
· hemoglobin
oxyhemoglobin -
O2 attached to iron (bright red)
deoxyhemoglobin -
O2 detaches from iron (dark red)
carbaminohemoglobin -
CO2 combined with globin's amino acids
EPO & Negative Feedback Blood Doping
· make 2 RBC million/sec
· controlled by erythropoietin (EPO), a hormone
· negative feedback
tissue O2 levels decrease kidneys release EPO
stimulates red bone marrow to make RBCs
RBC count increases tissue O2 levels increase
Leukocytes - WBC Platelets
· 4,800-10,800 per microliter · aka thrombocytes
· NO hemoglobin (appear white)
· no nucleus
· live a few days to several years
· about half the size of RBC
· defend body against foreign invaders
· granulocytes
· live about 10 days
neutrophils - most numerous, polymorphonuclear, · 150,000-400,000 per microliter
first to respond to infections, phagocytes · pieces of megakaryocytes
eosinophils - two-lobed nucleus, granules pick · important in initiating the blood clotting process
up red stain (eosin), attack parasitic worms
basophils - rarest, granules pick up blue (basic),
stain, U-shaped nucleus, release histamine
· agranulocytes
lymphocytes - large, purple nucleus, B or T, involved in
immunity
monocytes - largest leukocyte, U-shaped nucleus,
macrophages
