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.
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October 12, 2005
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.
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.
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
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.
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
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.
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.
The primary factor influencing V0 max is arteriovenous (A-V) oxygen difference.
The primary factor is CARDIAC OUTPUT!!!
“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)
1.) 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!
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)
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
1.) also part of innate system response
c.) natural killer (NK) cells
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
1.) produce cytokines
2.) producing antibodies
4.) memories of previous infections
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
A. Acute Exercise
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.