EEOB 410
Discussion Questions Week 8
1. Label the diagram below:
see lecture
2. Circle the correct answer: Skeletal muscle fibers contain one/many nucle(us/i).
3. Explain the following phenomenon regarding high altitude physiology:
”On arrival at 14,000 feet, they will increase ventilation by ~ 65%. Three days
later their ventilation will increase by ~ 400%.”
at altitude: increase ventilation to get more oxygen (up to 65%); increasing
ventilation also increases blood pH
body sensitive to that ph change; natural inhibition that prevents increasing
ventilation any further
Over time, body overcomes inhibition
4. Below is a graph showing quantity of oxygen in the blood of a person dwelling at
sea level (sea-level dweller). What might you expect to see in a graph of the same
for a person who has spent their life at high altitude? Draw your prediction on the
graph below.
see lecture
5. List 4 mechanisms that animals employ to cope with life at high altitude.
-
increase in pulmonary ventilation-most all animals breathe faster at high
elevation-immediate response
increase in number of RBC
increased vascularity of peripheral tissues
increased ability of tissues to use O2 despite low PO2-- more
mitochondria
6. What is erythropoitin (EPO)? Explain how this compound can be exploited by
endurance athletes.
EPO: increase RBC production – athletes can use for more efficient delivery of
O2 to target tissues
7. What is hypoxia? List the acute affects of hypoxia.
def: body is deprived of adequate oxygen
1. mental fatigue 2. drowsiness 3. lassitude 4. muscle fatigue
8. Define pulmonary edema. What would you expect the pH to be of a patient with
pulmonary edema? What is the cause of edema?
def: abnormal buildup of fluid in the arid sacs (alveoli)
pH: high
cause = pressure in capillaries forces fluid into lungs
9. At each end of a muscle fiber, the sarcolemma fuses with a ___________, which
collect into bundles and insert into _____________.
tendon fiber; bones
10. Explain the etiology of the “khumbu cough,” a dry cough experienced at high
altitude.
cough developes because water vapor pressure is very low at altitude; air dries
the trachea, causing a cough
11. What does the acronym HACE stand for? What causes HACE?
high altitude cerbral edema; same cause as pulmonary edema—pressure forces
fluid into brain (lungs in pulm.)
12. Identify the following in the figure below: A band, I band, Z line, H zone,
nucleus.
see lecture
13. What are the roles of titin and nebulin in muscle fiber structure?
structural proteins that help align actin and myosin
titin: elastic and gives muscle ability to spring back when stretched.
nebulin: inelastic…runs length of thin filament, stabilizes it.
14. Fill in the blanks for the 3 posulates of the sliding theory of muscle contraction:
a.
b.
c.
during contraction, ________ shorten
during contraction, ________ filaments slide past ________ filaments
cross-bridges form between ________ and ________, providing the force
that draws filaments past one another
sarcomeres; actin, myosin; actin, myosin (or other way around)
15. ________ is a divalent ion important in muscle physiology.
Ca++
16. Actin is composed of: ______________________, of which ____________ has
a strong affinity for calcium.
F-actin filaments, tropomyosin, troponin (I, T, C); troponin C
17. What evidence suggests that the active site on actin is covered by the
tropomyosin-troponin complex?
- actin sans troponin-tropomyosin binds immediately and strongly to heads of
myosin molecules
- add trop/t-mysin complex; binding between actin and myosin inhibited
18. Outline the interaction of ATP and Ca++ in muscle contraction:
1. myosin head binds ATP before contraction
2. Ca++ enters cell; actin head exposed (mechanism unknown)
3. energized myosin tilts (cleaves ATP to ADP), pulls actin along
4. new ATP attaches to site, causing detachment from actin
5. if Ca++ present, cycle re-initiates
19. Explain isometric and isotonic contraction.
isometric – contraction where muscle maintains length
isotonic – contraction where muscle shortens