Unit III: HomeostasisBlood

Chapter 17

pp. 575-585

Review

1. The most effective buffer in the intracellular fluid is: a.) phosphate; b.) protein; c.) bicarbonate; d.) carbonic acid

2. A blood pH of 7.2 caused by inadequate pulmonary ventilation would be classified as _________.

3. Tubular secretion of hydrogen ions would cease if the acidity of the tubular fluid fell below a value called the _________.

4. (T/F) The bicarbonate system buffers more acid than any other chemical buffer.

5. Acids ____________ hydrogen ions in a solution, whereas, bases _______ them.

Functions of Circulatory System

• Fundamental purpose: transport substances from place to place

• Transport

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

• Protection

– Inflammation, WBCs, antibodies, and platelets

• Regulation

– fluid regulation, buffering, and heat

Presence of Potassium in Blood

>8 mEq/L in blood • cardiac arrhythmias

<2 mEq/L in blood:• muscular weakness•paralysis

Normal potassiumlevels in serum(3.5–5.5 mEq/L)

Factors Promoting Hypokalemia Factors Promoting HyperkalemiaDiuretics (Lasix)

↑ volume of urineproduced

Aldosteronism

overstimulates sodiumretention & potassiumloss

Chronically lowbody fluid pH

Kidney failure Several drugs promotediuresis by blocking Na

reabsorption at thekidneys.

Hypokalemia Hyperkalemia

Centrifuge

Withdrawblood

Plasma(55% of whole blood)

Buffy coat: leukocytesand platelets(<1% of whole blood)

Erythrocytes(45% of whole blood)

Formedelements

Blood Composition

• Adults have 4-6 L of blood

• Plasma – – Water, proteins, nutrients, electrolytes,

nitrogenous wastes, gases, and hormones (Table 18.2 p. 687)

• Serum– Lacks fibrinogen

Plasma Proteins

• 3 major categories of plasma proteins:– albumins - most abundant

• contributes to viscosity and osmolarity influences blood pressure, flow and volume

– globulins (antibodies) • provide transport, clotting, and immunity• alpha, beta and gamma globulins

– fibrinogen • precursor of fibrin help form blood clots

• Plasma proteins formed by liver – except gamma globulins (produced by plasma cells)

Formed Elements of Blood

•Erythrocytes

•Platelets

•Leukocytes

–Granulocytes

Neutrophils

Eosinophils

Basophils

–Agranulocytes

Lymphocytes

Monocytes

Properties of Blood

• Viscosity -– whole blood 5 times as viscous as water

• Osmolarity (total molarity of dissolved particles that can’t pass through blood vessel wall)– high blood osmolarity

• raises blood pressure

– low blood osmolarity • lowers blood pressure

Properties of Blood

• Hematocrit – (packed cell volume)– Females: 37-48%– Males: 45-52%

• pH: 7.35 - 7.45• RBC count:

– Females: 4.2-5.4 million/µL– Males: 4.6-6.2 million/µL

• Total WBC count: 5000 – 10,000 /µL• Volume/Body weight: 80-85 mL/kg

– Female: 4-5L– Male: 5-6L

Erythrocytes (RBCs)

• Disc-shaped cell with thick rim

• Gas transport

– increased surface area/volume ratio

• due to loss of organelles during maturation

• increases diffusion rate of substances

– 33% of cytoplasm is hemoglobin (Hb)

• O2 delivery to tissue and CO2 transport to lungs

• Carbonic anhydrase (CAH)

Erythrocytes and Hemoglobin

• Common measurements:

– Hematocrit (packed cell volume)

– Red blood cell count

– hemoglobin concentration of whole blood

• men 13-18g/dL; women 12-16g/dL

• Values are lower in women

– androgens stimulate RBC production

– women have periodic menstrual losses

– Hematocrit is inversely proportional to % body fat

Erythropoiesis

• 2.5 million RBCs/sec (hematocrit value of 20mL of RBC/day)• Development takes 3-5 days

– reduction in cell size, increase in cell number, synthesis of hemoglobin and loss of nucleus

Macrophages in liver,spleen, and bone marrow

Fe2+

90%

10%

Fe2+ transported in circulationby transferrin

Average life span ofRBC is 120 days

Hemolysis

Heme

Biliverdin

Bilirubin

Amino acids

New RBCsreleased into

circulation

RBCformation

Ejection ofnucleus

Events Occurring in the Red Bone Marrow

Multipotent stem cells

Proerythroblasts stimulatedby erythropoietin (EPO)

Erythroblast

Roughly four days of differentiation

Retilculocytes remain in the bone marrow for 2 more days

Start

Erythrocyte Homeostasis

• Negative feedback control

– drop in RBC count causes kidney hypoxemia

– EPO production stimulates bone marrow

– RBC count in 3 - 4 days

• Stimulus for erythropoiesis

– hemorrhaging, blood loss

– low levels O2

– abrupt increase in O2 consumption

– loss of lung tissue in emphysema

Anemia

•Inefficient amount of red blood cells•Causes:

inadequate erythropoiesis•Kidney failure•Iron-deficiency•Vitamin B12 deficiency

blood loss RBC destruction

•Consequences:HypoxiaDecreased blood osmolarityDecreased blood viscosity

Erythrocyte Disorders

Sickle Cell Disease and Thalassemia

• Hereditary Hb ‘defect’ of African Americans and Mediteraneans

– recessive allele modifies hemoglobin structure

– sickle-cell trait - heterozygous for HbS

• individual has resistance to malaria

– sickle-cell disease - homozygous for HbS

• individual has shortened life

– low O2 concentrations sickle shape

– stickiness agglutination blocked vessels – intense pain; kidney and heart failure; paralysis; stroke

RBC

Surface antigens Antigen-antibody complexOpposing antibodies Hemolysis

Antigens and Antibodies

• Antigens (agglutinogens)

– unique molecules on all cell surfaces

• used to distinguish self from foreign

• Antibodies (agglutinins)

– secreted by plasma cells

– Appear 2-8 months after birth; reach maximum at 10 yr.

– Transfusion reaction

• Agglutination :

ABO Blood Groups

• Your ABO blood type is determined by presence or absence of agglutinogens on RBCs and agglutinins in blood plasma.

• most common/universal donor - type O

• Rarest/universal recipient - type AB

Type A Type AB Type O

RBCs lacking both A and Bantigens.

RBCs with antigen A only. RBCs with antigen B only. RBCs with both A and B antigens.

Type B

Surfaceantigen A

Surfaceantigen B

Plasma contains anti-Bantibodies, which will attackType B surface antigens.

Plasma contains anti-Aantibodies.

Plasma has neitheranti-A nor anti-B antibodies.

Plasma contains bothanti-A and anti-B antibodies.

ABO Group Genetics

• A and B alleles are dominant over O; but codominant to each other

Genotype Antigen Phenotype

AA A A

AO A A

BB B B

BO B B

AB A and B AB

OO Neither O

A AB

BAB BA

AB A B

Rh Group

• 3 antigens: C, D, E

• Rh (D) agglutinogens

– Rh+ blood type has D agglutinogens on RBCs

– Rh frequencies vary among ethnic groups

• Anti-D agglutinins not normally present

– form in Rh- individuals exposed to Rh+ blood

• no problems with first transfusion

First Pregnancy of an Rh– Motherwith an Rh+ infant

Very few fetal cells enter the maternal circulation.

Exposure to fetal red blood cell antigens generally occurs during delivery.

A woman’s first infant is not affected.

During First Pregnancy

Hemorrhaging at Delivery

Maternal Antibody Production

During Second Pregnancy

Rh antigen onfetal red blood cells

Maternal antibodiesto Rh antigen

Maternal

Fetal

Maternal

Fetal blood supplyand tissue

Maternal blood supplyand tissue

Placenta

Rh+

fetus

Rh–

motherRh–

mother

Rh+

fetus

Maternal

Fetal

Maternalantibodies

Hemolysis offetal RBCs

Second Pregnancy of an Rh– Motherwith an Rh+ Infant

Maternal anti-Rh antibodies present.

These antibodies destroyfetal RBCs dangerous anemia.

Need for blood cells ↑

Leave bone marrow under-development.

Hemolytic Disease of the Newborn

Anti-A Anti-B Anti-DBloodtype

A+

B+

AB+

O–

Results of blood typing tests on blood samples from four individuals