lecture27nth - cause of proportion shift: Cardiovascular...

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Unformatted text preview: cause of proportion shift: Cardiovascular response to exercise vasodilation in skeletal muscles vasoconstriction elsewhere CO >4x proportion >4x blood (liters/min) to skeletal muscles ~20x Figure 25-7 Limitations to athletic performance • oxygen delivery to muscles by blood • oxygen delivery to blood by lungs • oxygen use by muscle cells • force production by muscle cells ventilation reaches 65% of max. when cardiac output reaches 90% of max (so cardio system sets limit before ventilation system) 1999. Scientific American. How do muscle cells respond to exercise by becoming stronger and thicker? Transcription of muscle proteins affected by large number of factors (sex hormones, thyroid hormones, growth factors, etc.). Example: anabolic steroids (synthetic version of testosterone) combine with transcription factors to turn on genes and make more muscle proteins. [side effects include high cholesterol levels, changes in hair, atrophy of testicles, hair loss, infertility, aggression, etc.] (optional reading) from: 2005. Exercise controls gene expression. American Scientist. (optional reading) Presence of Y sex chromosome determines male gender XXY (rare) male Y0 (rare) die (missing X genes) Y chromosome has SRY gene (sexdetermining region of Y chromosome) Figure 26-2 Internal organ development in males and females gonads - organs that produce gametes genitalia - external reproductive organs or structures (usual, but see p. 829 that mentions "internal genitalia") Figure 26-3a External organ development in males and females Figure 26-3b Testes and ovaries both produce hormones in addition to producing gametes Gametogenesis germ cells germ cells Figure 26-5 Synthesis pathways for steroid hormones "male" sex hormones "female" sex hormones Figure 26-6 ...
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This note was uploaded on 12/01/2010 for the course BIO SCI Bio Sci E1 taught by Professor Catherineloudin during the Spring '10 term at UC Irvine.

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