Boredom

I was so freaking bored that I actually read the first 3 units of Exercise Physiology in the Biology textbook and made notes. -.-

Ventilation:

1. Air flow is tidal (enters and leaves via same route) - Therefore there is always a mixture between residual air and incoming air that dilutes it.

2. Tidal volume = Amount of air inhaled/exhaled

3. Vital capacity = Volume of air expelled after maximum inhalation

4. Total lung capacity = Volume of air in lungs after maximum inhalation (Vital capacity + Residual volume)

During exercise:

1. Sub-maximal exercise: Ventilation rate increases and then steadies - Plateaus out whereby ventilation rate is enough to sustain level of exercise (Supplies enough energy to contracting muscles)

2. Maximal exercise: Ventilation rate increases continuously until exercise ends

Effects of Training and Exercise:

1. Aim: Achieve long term favourable physiological adaptation; body can cope better with stresses imposed when doing the sport

2. Sub-maximal exercise for several weeks reduces oxygen consumption by pulmonary system's muscles (diaphragm and intercostal muscles), therefore less oxygen is consumed by ventilatory muscles, leaving more available for locomotory muscles.

3. Tidal volumes increase and ventilation rates decrease with sub-maximal exercise training.

4. Percentage oxygen in trained people's exhaled breaths: 14-15% compared with 18% in untrained people

5. No effect on lung volume (unchanged vital capacity), but maximum ventilation rate increases.

6. Stroke volume: Volume of blood pumped out of heart with each contraction (difference in volume of blood before and after ventricular contraction)

7. Cardiac output: Volume of blood pumped out by heart per minute (stroke volume x heart rate = cardiac output)

8. Entire volume of our blood flows through pulmonary and systemic circulations while physically inactive.

9. Venous return: Volume of blood returning to heart via veins per minute.

10. When venous return increases, so does cardiac output (as there is more blood to pump out).

11. About 70% of our total blood is in veins.

12. Women have about 25% lower cardiac output than men (due to smaller body size).

13. Blood movement in veins depends partly on pressure from surrounding tissues, hence strenous activity (which causes active skeletal muscle contraction) increases venous return.

14. Cardiac muscle is slightly elastic. Ventricle walls are stretched during exercise. Also, ventricle walls are progressively thickened. This results in cardiac hypertrophy (increased ventricular capacity and thicker walls = larger heart).

15. Two independent antagonistic nerves run from cardiac control centre to pacemaker. With increased training, parasympathetic nerve has more influence (more impulses) than sympathetic nerve, so at rest, heart rate is steadily lowered. This phenomenon is known as bradycardia.

16. For trained athletes: At rest, increased ventricular cavities allows heart to be filled with more blood, and also strengthened cardiac muscles increases volume of blood pumped out i.e. stroke volume increases. This means that an cardiac output of an athlete is the same as a normal person but with less strokes per minute.

17. During physical activity, heart rate is raised and is similar in both trained and untrained people. However, stroke volume is more in athletes - therefore cardiac output will be more for athletes.

Blood Redistribution during Exercise:

1. If all veins were fully dilated, they would be able to hold about 20 litres of blood. However, our blood circulations hold merely 5-6 litres (males) and 4-5 litres (females) of blood.

2. Circulation of blood is controlled by vasodilation and vasoconstriction.

3. During physical activity, the pre-capillary sphincter contracts (vasoconstriction), reducing blood flow to capillaries and corresponding body tissues (tissues are 'by-passed').

4. However, blood flow to the brain, lungs and kidney do not vary.

It was quite enlightening I must say. Now I shall recommence reading Map of the Invisible World.