immunological system dr. moran october 12, 2005 exs 558
Post on 21-Dec-2015
214 Views
Preview:
TRANSCRIPT
Immunological System
Dr. Moran
October 12, 2005
EXS 558
Review Questions #1, 2
1.) TRUE/FALSE
Normal and trained athletes have approximately the same resting cardiac outputs.
2.) Explain how this apparent discrepancy can occur.Endurance trained athletes have a larger stroke volume (EDV-ESV) than sedentary individuals and as a result have a lower resting HR. Recall that cardiac output (Q) equals the product of HR and SV.
Review Question #3
3.) Explain the extent and mechanisms that blood is redistributed during exercise as opposed to at rest?
At rest only ~16% of blood is directed towards skeletal muscle with the majority of blood flow going to internal organs (i.e. liver + kidneys). During exercise this % increases to 84%. This redistribution is possible through selective vasoconstriction and vasodilation of the vasculature system. Capillary diameter is manipulated through both (1) autoregulation and through (2) extrinsic neural control.
Review Question #4
4.) Which of the following is NOT a function of blood?
a.) buffer and balance acidic levels
b.) regulate temperature
c.) transport gas, nutrients, and wastes
d.) metabolize plasma FFA
Review Question #5
5.) Explain the changes in blood plasma and hematocrit following a marathon training program.Following endurance training the blood plasma levels increase as does the red blood cell count, however, since the blood plasma gains are greater than the RBC gains overall hematocrit levels are LOWER post-training program. An increased blood plasma level decreases blood viscosity and lowers systolic blood pressure, further aiding in oxygen transport.
Review Question #6, 7
6.) TRUE/FALSE
Due to the increased metabolic needs, the hemoglobin affinity of oxygen is increased when blood pH levels are lowered.
7.) This phenomenon is called _____________THE BOHR EFFECT
Review Question #8
8.) Explain the primary reasons why stroke volume values can be up to 60% higher in endurance trained athletes than sedentary people.
The major reason that stroke volumes are increased in endurance trained athletes is because of positive changes of EDV. EDV can be increased through (1) increased left ventricle chamber size, (2) suctioning mechanism, (3) increased blood plasma levels.
Review Question #9
9.) Explain the significance of the Frank-Starling mechanism.
With an increased EDV the left ventricle walls becomes stretched stimulating the viscoelastic properties of the smooth cardiac muscle walls. This stretch allows a greater passive muscle contribution and thus a more powerful ejection force. As a result of the more forceful contraction less blood remains in the chamber and cardiac efficiency is improved.
Review Question #10
10.) TRUE/FALSE
The primary factor influencing V0 max is arteriovenous (A-V) oxygen difference.
The primary factor is CARDIAC OUTPUT!!!
Exercise Immunology
“Exercise can be employed as a model of temporary immunosuppression that occurs after severe physical stress. Furthermore, exercise that is associated with muscle damage may represent a model of the acute-phase response to local injury”
Pedersen & Nieman
(1998)
Two Sides of the “Immune” Coin
Immunological System & Exercise1.) regular moderate exercise is beneficial to a
person’s health by stimulating the immuno-response
2.) intense training may increase the athlete’s susceptibility to infection (i.e. upper respiratory infection)
Research focused on the effect of exercise volume and intensity on the immune response!
Functional Immune Divisions
INNATE
1.) body’s natural response
2.) first line of defense against infectious agents
3.) does not get better from exposure (it is what it is)
COMPLEMENT1.) also part of innate system response
2.) includes:
a.) lysozymes
b.) phagocytes
c.) natural killer (NK) cells
ADAPTIVE
1.) used if innate system unable to destroy infectious agent
2.) infectious-specific reaction
3.) has a memory
4.) antibodies produced to quickly & efficiently respond to infectious threats
Cells of the Immune System
Leukocytes (white blood cells) Composed of:
1.) Lymphocytes (20%): have receptors for antigens
a.) T cells: develop in thymus
b.) B cells: develop in bone marrow
c.) Natural Killer Cells (NKC)
2.) Monocytes (10%): produce cytokines (stimulate inflammatory response)
3.) Granulocytes (70%): part of initial response to foreign pathogens (PHAGOCYTOSIS)
a.) Neutrophils: attracted to sites of infection/injury
b.) Eosinophils: parasitic infection
c.) Basophils & Mast Cells: allergies and inflammatory reactions
Lymphocytes
Comprised of T cells, B cells, and NKC each have separate function T cells/B cells: major effectors of adaptive immunity NKC: innate immunity capability
Part of initial immune system Responsible for:
1.) produce cytokines
2.) producing antibodies
3.) cytotoxicity
4.) memories of previous infections
What is phagocytosis? Phagocytic cells brought to sites of infection and inflammation Have surface receptors increases affinity to variety of microorganisms After attachment phagocytes engulf and destroy microorganism
Immunoglobulin (Antibodies)
Glycoproteins found in ALL bodily fluids ALL antibodies immunoglobins But not vice-versa Combat infections through direct & indirect means
DIRECT: bind to antigens on microorganisms to prevent it from entering host
INDIRECT: stimulate other phagocytic cells that kill organism (more prevalent)
5 distinct classes
Immunoglobin Classes (TABLE 5.1)
Immunoglobin % of total pool Function
IgG 70-75% Major antibody of secondary immune response
IgA 15-20% In saliva & mucous membranes and acts against infections entering through mucous
IgM 10% In mucosal secretions and seen early in immune response
IgD <1% On membrane of circulating B cells
IgE trace Associated with immediate sensitivity to asthma and hay fever
Cytokines (TABLE 5.2)
Regulate growth factors Involved with immediate inflammatory response Soluble (in plasma) Commonly types
Interleukuen (IL) Inflammatory mediation Enhance phagocytic function Stimulate further cytokine function IL-6: increased substantially following muscle damaging activity IL-1β: elevated levels in brain following a faitguing downhill run in
mice (Carmichael et al., 2005).
IL-6 linked to Muscle Damage
Complement System
Group of proteins found in blood Primary Function: initiate and amplify inflammatory
response Biological Functions:
1.) recruit macrophages and neutrophils to site of injury
2.) lysis of bacteria
3.) opsonization of pathogens
Opsonization = process that alters bacteria by adding an antibody (C3b-component),this increases the likelihood that they will be engulfed by phagocyte
Opsonization & Phagocytosis
Exercise Induced Changes
I. Leukocyte (including lymphocytes) ResponseA. Acute Exercise
B. Long Term
II. Phagocytic Cell Function
III. Cytokines & Complement System
IV. Immunoglobulins
V. Athlete Immune Reponse
Leukocyte Effect of Acute Exercise
Circulating leukocyte [ ]’s ↑ after an acute bout of exercise Most notable within neutrophils but also within monocytes
and lymphocytes Magnitude of change dependent on both
DURATION and INTENSITY Positive relationship Short-duration, high intensity
150-180% above resting values Decline begins 30-60min post-exercise Can remain elevated up to 2hrs depending on exercise dose
Endurance Exercise Circulating levels may increase 2-3 fold during exercise May remain elevated up to 6hr post-exercise
Lymphocyte Response Consistent increase during and immediately after exercise After prolonged OR intense workouts NKC levels may be
decreased below resting levels for several hours OR even days post-exercise
Leukocyte Effect of Acute Exercise (continued)
Neutrophil Effect of Heavy Training Volume
Pyne et al. (1995)
Mature WBC
Represent about 54-65% of leukocyte count normally
Neutrophil counts were suppressed in elite swimmers following periods of heavy training
Counts raised during a “peaking” or tapering phase leading into the NCAA championships
Natural Killer Cells (NKC) Part of the initial immune response Kill a large number of cells through
secretion of toxic substances Levels not affected during a 2.5-3.0
hour run Levels diminished significantly for up
to 6 hours post-operative
T cells and B cells (lymphatic tissue) display a similar trend during this experiment
Leukocytes
NKC
NKC Following a Marathon
Baseline NKC values substantial higher
Substantial reduction following marathon Implications?
Still at the sedentary values
Research studies (cross sectional design) have shown no differences in athletes vs. nonathletes
BUT leukocyte values may be affected during periods of heavy training volume as opposed to smaller training volume
Leukocyte Effect of Long-Term Training
Training Volume ↑ ↓ Leukocyte count Increased susceptibility to infectious attack
Training Intensity ↑ no change in leukocyte count
Response also sensitive to type of exercise (aerobic vs anaerobic)
Leukocyte Effect of Long-Term Training (continued)
Phagocytic Cell Function
Increased circulating phagocytic values does NOT indicate anything about cell function (be careful not to assume activity when reading articles)
Acute exercise positive effect
Prolonged Training program deleterious effect 20-30% less phagocytic activity in endurance athletes Also overall decreases in:
Migrating ability Neutrophil adherence Granule content Sensitivity to stimulation
Phagocytic Cell Function (con’t)
What is the significance of decreased phagocytic cell activity in endurance athletes? More susceptible to infection
OR Smith et al. (1990) argues that lower sensitivity of
neutrophil function indicates a good adaptation that limits inflammatory response to chronic tissue damage
Cytokines & Complement System
Reminder: these are mediators of the INNATE immune system
Effect on Complement System from acute exercise Contradictory results
MacKinnon (1999): complement system levels may remain elevated for several hours post-exercise and are responsible for cleaning proteolytic fragments released from muscles
Cytokines & Complement SystemEndurance Athletes
Have lower resting levels and response following a graded exercise protocol as compared to non-athletes
Significant Adaptation? Lowered response thought to reflect long-term adaptation
to chronic inflammation from intense daily running
Cytokine Response Conflicting reports – difficult to determine response Some report no resting differences between athletes and
non-athletes
Immunoglobins Important for the adaptive immune system For athletes (runners, cyclists) serum levels of immunoglobin did not
alter much during or after exercise. However, response was elevated up to 1.5 hrs following exercise for
overweight females Resting salivary IgA levels reduced in athletes involved high-
intensity training programs Suppressed immunoglobin levels may indicate greater chance of
upper respiratory tract infection (URTI) in athletes 40-60% ↓ of IgA following an acute exercise bout (can remained lower
for up to 24 hrs - IMPLICATIONS)
URTI
URTI – is it really a risk? Moderate Exercise
Nieman et al. (1993) reported that a 50% reduction in URTI in women exercising 5 days a week compared with sedentary age-matched controls
Intense/Prolonged Exercise Bout Larabee (1901) – he noted that the WBC differential in four runners at
the Boston Marathon paralleled those seen in diseased conditions Neiman et al. (1990) reported that 12.9% of runners in a marathon
experienced URTI symptoms the week after the race as compared to 2.2% of control runners.
Greater URTI incidence seems to occur during the 2 weeks following a hard race/run greater than 2-3 hours in duration
Appears to be limited to endurance athletes (marathon, triathlon, orienteering, etc.)
Is infection risk linked to exercise workload? Medicine & Science in Sports & Exercise. 32(7) Supplement:S406-S411, July 2000
Abstract: Anecdotal, survey, and epidemiological data suggest that endurance athletes are at an increased risk for upper respiratory tract infection (URTI) during periods of heavy training and the 1- to 2-wk period after race events. The majority of athletes, however, who participate in endurance race events do not experience illness. Of greater public health importance is the consistent finding of a reduction in URTI risk reported by fitness enthusiasts and athletes who engage in regular exercise training while avoiding overreaching/overtraining. Although it naturally follows that infection risk should in some way be linked to acute and chronic exercise-induced alterations in immunity, attempts thus far to measure this association have been unsuccessful. There is growing evidence that for several hours subsequent to heavy exertion, several components of both the innate and adaptive immune system exhibit suppressed function. The immune response to heavy exertion is transient, however, and further research on the mechanisms underlying the immune response to prolonged and intensive endurance exercise is necessary before meaningful clinical applications can be drawn. Some attempts have been made through chemical or nutritional means (e.g., indomethacin, glutamine, vitamin C, and carbohydrate supplementation) to attenuate immune changes after intensive exercise to lower the risk of infection. No consistent relationship between nutritional interventions, exercise immunology, and alteration in URTI risk has yet been established.
Recovery of running performance following muscle-damaging exercise: Relationship to brain IL-1β
Exercise immunology: integration and regulation
Exercise-induced immune changes – an influence on metabolism
top related