Unit III: Homeostasis Blood Chapter 18 pp. 684 - 699.
-
date post
22-Dec-2015 -
Category
Documents
-
view
214 -
download
0
Transcript of Unit III: Homeostasis Blood Chapter 18 pp. 684 - 699.
Unit III: HomeostasisBlood
Chapter 18
pp. 684 - 699
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
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: (Table 18.3 p. 687)
– 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
– 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
• Erythrocyte colony forming unit (ECFU)– erythropoietin (EPO)
• Erythroblasts multiply and synthesize hemoglobin • Discard nucleus to form a reticulocyte
– 0.5 to 1.5% of circulating RBCs
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
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
– antibody molecule binds to >2 antigens
– Antigen-antibody complex
ABO Blood Groups
• Your ABO blood type is determined by presence or absence of agglutinogens on RBCs and agglutinins in blood plasma.
Antigen on RBC Antibody in plasma
– type A: A anti-B
– type B: B anti-A
– type AB: A and B neither
– type O: neither anti-A and anti-B
• most common/universal donor - type O
• Rarest/universal recipient - type AB
Type A
Type B
Type AB
Type O
© Claude Revey/Phototake
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 or pregnancy
Leukocytes (WBCs)
• 5,000 to 10,000 WBCs/L
• Conspicuous nucleus
• Travel in blood before migrating to connective tissue
• Protect against pathogens
Leukocyte Descriptions• Granulocytes
– neutrophils (60-70%) - fine granules; 3 to 5 lobed nucleus in bacterial infections
– eosinophils (2-4%) - large rosy granules; bilobed nucleus in parasitic infections or allergies
– basophils (<1%) - large, violet granules in chicken pox, sinusitis, diabetes• Histamine and heparin
Leukocyte Descriptions
• Agranulocytes– lymphocytes (25-33%) - round, uniform dark violet nucleus
in diverse infections and immune responses– monocytes (3-8%)
• largest WBC; ovoid, kidney-, or horseshoe- shaped nucleus in viral infections and inflammation
Leukopoiesis
• Leukocyte life cycle– pluripotent stem cells CFU’s
• myeloblasts – form neutrophils, eosinophils, basophils• monoblasts - form monocytes• lymphoblasts - form 3 types of lymphocytes
– Colony-stimulating factors (CSF)
• WBCs provide long-term immunity (decades)
Abnormal Leukocyte Counts
• Leukopenia - low WBC count (<5000/L)
– causes: radiation, poisons, infectious disease
– effects: elevated risk of infection
• Leukocytosis = high WBC count (>10,000/L)
– causes: infection, allergy and disease
– differential count - distinguishes % of each cell type
• Leukemia = cancer of hemopoietic tissue
– myeloid and lymphoid - uncontrolled WBC production
– acute and chronic - death in months or 3 years
– effects – deficiency of competent formed elements; impaired clotting
Platelets
• Small fragments of megakaryocyte
– no nucleus
– 40% stored in spleen
• Normal Count - 130,000 to 400,000 platelets/L
• Functions:
– vasoconstrictors
– platelet plugs
– secrete clotting factors
– initiate formation of clot-dissolving enzyme
– phagocytize bacteria; chemically attract neutrophils and monocytes to sites of inflammation
– secrete growth factors
Hemostasis
• All 3 pathways involve platelets
HemostasisVascular Spasm
• Causes– pain receptors – smooth muscle injury– platelets release serotonin (vasoconstrictor)
• Effects– prompt constriction of a broken vessel
• pain receptors - short duration• smooth muscle injury - longer duration