biol 117 – ch 18: cardiovascular system: blood

blood

blood

a fluid connective tissue composed of formed elements and plasma that’s transported through the cardiovascular system

functions of blood

• transports nutrients, wastes, and respiratory gases

• regulates body temp, pH, and fluid levels

• protects body against activities of pathogens

physical characteristics of blood

color, volume, viscosity, plasma concentration, temp, pH

color of oxygen-rich blood

this type of blood is bright red or almost scarlet

color of oxygen-poor blood

this type of blood is dark red

5 L (but can range from 4-6 L)

average volume of blood in an adult

viscosity

thickness of a solution; provides resistance to fluid flow

blood is about 4-5 times more viscous than water

comparison of viscosity between blood and water

plasma concentration

• the relative concentration of solutes in plasma

• typically 0.9% concentration

temperature of blood

• the temp of blood is almost 1 degree C (or 2 degrees F) higher than measured body temp —> blood warms areas through which it travels

• ex: if your body temp is 37 degrees C, your blood temp is 38 degrees C

7.35-7.45

normal pH for blood

erythrocytes, buffy coat, and plasma

centrifugation separates blood into these 3 components

buffy coat

composed of leukocytes and platelets

hematocrit

represents the percentage of formed elements in blood

males typically have higher hematocrits than females

this gender typically have higher hematocrits than the other

formed elements

this type of elements in blood can be viewed in a blood smear

formed elements

consists of buffy coat + erythrocytes

blood plasma

a mixture of water, plasma proteins, and other solutes

about 55% of whole blood

blood plasma forms about this percent of whole blood

whole blood

both plasma and formed elements

plasma is similar in composition to interstitial fluid, except it contains proteins

what’s the difference between plasma and interstitial fluid?

albumin

• ~58% of plasma proteins

• exerts osmotic force to retain fluid within the blood

• contributes to blood’s viscosity

• transport selected molecules (ex: ions, lipids, hormones)

globulins

• ~37% of plasma proteins

• alpha-”[term]” transport lipids and some metal ions (ex: copper)

• beta-”[term]” transport lipids and iron ions

• gamma-”[term]” are antibodies that immobilize pathogens

fibrinogen

• ~4% of plasma proteins

• participates in blood coagulation (clotting)

regulatory proteins

• <1% of plasma proteins

• consists of enzymes and hormones

plasma proteins

• ~7% of plasma

• all of these buffer against pH changes

• albumin; globulins; fibrinogen and other clotting proteins; and regulatory proteins

other solutes in blood plasma

• ~1% of blood plasma

• electrolytes, nutrients, respiratory gases, wastes

electrolytes

• other solutes of blood plasma

• help establish, maintain, and change membrane potentials, maintain pH balance, and regulate osmosis

• ex: sodium, potassium, calcium, chloride, iron, bicarbonate, hydrogen

nutrients

• other solutes of blood plasma

• energy source; precursor for synthesizing other molecules

• ex: amino acids, glucose, cholesterol, vitamins, fatty acids

respiratory gases

• other solutes of blood plasma

• oxygen is needed for aerobic cellular respiration

• CO2 is a waste product produced by cells during this process

wastes

• other solutes of blood plasma

• serve no function in the blood plasma

• they merely are being transported to the liver and kidneys, where they can be removed from the blood

• ex: breakdown products of metabolism, such as lactate, creatinine, urea, bilirubin, ammonia

erythrocytes

• transport respiratory gases

• biconcave disc structure

leukocytes

serve some roles in protecting the body from harmful substances

platelets

participate in hemostasis

hematopoeisis

the process by which formed elements develop

red bone marrow

hematopoeisis takes place here

hemocytoblasts

• hematopoiesis starts with these hematopoietic stem cells

• multipotent

multipotent cells

can differentiate and develop into many different kinds of cells

myeloid line

forms erythrocytes, all leukocytes except lymphocytes, and megakaryocytes (produce platelets)

lymphoid line

forms only lymphocytes

hemoglobin

• a pigmented protein within mature erythrocytes

• transports oxygen and CO2

120 days

aged erythrocytes are broken down and their components recycled after about this many days in the blood

surface antigens on the erythrocytes

blood type is determined by this

erythropoiesis

erythrocyte production

leukopoiesis

leukocyte production

thrombopoiesis

production of platelets

megakaryoblast

• a committed cell from the myeloid stem cell

• BEFORE megakaryocyte (think b before c)

erythropoietin (EPO)

hormone that controls erythropoiesis

kidneys

organ that is primary producers of EPO

liver

this organ secretes a small amount of EPO

decrease in blood oxygen levels

this is the initial stimulus for EPO release

how erythropoietin (EPO) regulates erythrocyte production

1. stimulus: decreased blood oxygen levels

2. receptor: kidney detects decreased blood O2

3. control center: kidney cells release EPO into blood

4. effector: EPO stimulates red bone marrow to increase the rate of production of erythrocytes

5. net effect: increased #’s of erythrocytes enter circulation —> the erythrocytes are oxygenated and blood O2 levels increase

6. increased blood O2 levels are detected by the kidney —> inhibits EPO release by negative feedback

type A blood

• erythrocytes have surface antigen A

• plasma has anti-B antibodies

type B blood

• erythrocytes have surface antigen B

• plasma has anti-A antibodies

type AB blood

• erythrocytes have surface antigens A and B

• plasma has NEITHER anti-A not anti-B antibodies

type O blood

• erythrocytes don’t have surface antigen A or B

• plasma has BOTH anti-A and anti-B antibodies

Rh positive

• erythrocytes have surface antigen D

• plasma has NO anti-D antibodies

Rh negative

• erythrocytes have no surface antigen D

• plasma has NO anti-D antibodies unless exposed to Rh positive blood

agglutination

• process by which cells clump due to cross-linking by antibodies

• happens if a person is transfused with blood of an incompatible type

diapedesis

passage of leukocytes through the intact blood vessel wall

chemotaxis

a process in which leukocytes are attracted to a site of infection by the presence of molecules released by damaged cells, dead cells, or invading pathogens

neutrophils, eosinophils, basophils

3 types of granulocytes

lymphocytes and monocytes

2 types of agranulocytes

neutrophils characteristics

• granulocyte with multilobed nucleus (as many as 5)

• cytosol contains neutral, or pale, specific granules

neutrophils functions

• phagocytize pathogens, especially bacteria

• release enzymes that target pathogens

neutrophils approximate percentage

50-70% of total leukocytes (1800-7800 cells per microliter)

eosinophils characteristics

• granulocyte with bilobed nucleus

• cytosol contains reddish or pink-orange specific granules

eosinophils functions

• phagocytize antigen-antibody complexes and allergens

• release chemical mediators to destroy parasitic worms

eosinophils approximate %

1-4% of total leukocytes (100-400 cells per microliter)