AJ-5-Physiology-of-the-human-body

FUNCTION OF THE HEART
The oxygenated blood leaves the lungs and enters the left atrium of the heart through the pulmonary veins, passes through the mitral valve into the left ventricle, from where it is pumped through the aorta around the body, returning to the right atrium of the heart, depleted in oxygen, through the superior and inferior vena cava. From the right atrium the blood passes through the tricuspid valve into the right ventricle, from where it is pumped into the lungs via the pulmonary artery, picking up oxygen and releasing carbon dioxide before returning to its left atrium through the pulmonary veins.

Heart rate is calculated as the number of contractions (heart beats) of the heart in one minute and expressed as "beats per minute" (bpm). Heart rate is widely accepted as a good method for measuring intensity during running, swimming, cycling, and other aerobic activities. Exercise that doesn’t raise your heart rate to a certain level and keep it there for 20 minutes will not contribute significantly to cardiovascular fitness.

Table 2: Age category and heart rate

AGE CATEGORY HEART RATE /bpm BLOOD PRESSURE systolic/diastolic (mmHg) Newborns (< 28 days) 125 – 160 60/40 – 70/50 Infants (1 month – 1 year) 115 – 140 80/60 – 90/70 Young children (aged 1 – 5 ) 95 – 120 90/60 – 105/70 School children (aged 6 – 13) 85 – 100 95/60 – 120/75 Adolescents (aged 14 – 18) 65 – 80 120/70 – 130/85 Adults (> aged 18) 60 – 80 120/70 – 140/90

PHYSICAL FITNESS

Exercise is often recommended as a means of improving motor skills, fitness, muscle and bone strength, and joint function. Developing fitness will largely depend on how the components of fitness can be imbedded into a training program.

Physical fitness involves the performance of the cardiorespiratory system - the heart and lungs, and the muscular system of the body. As there are a number of different types of "fitness", it is best to look at fitness by examining the Components of Fitness. From a sporting perspective there are 3 basic components of fitness - endurance, speed and strength, with flexibility at the core of fitness influencing each component.

• Endurance is the ability of the heart and lungs to supply fuel to working areas of the body during sustained physical activity. To improve your cardiorespiratory endurance, it is necessary to perform activities that elevate your heart rate for a sustained length of time.

• Strength is the ability of the muscles to generate force in a short period of time. When you increase your strength, you're often also increasing the size of your muscles, however, athletes should develop their muscular strength and endurance in a manner that will improve performance, and will not simply build larger muscles.

• Strength endurance is a combination of strength and endurance, and is defined as the ability of the muscle to continue to perform generating the same force without fatigue.

• Speed endurance is a combination of speed and is the ability of the muscle to perform at the same speed without fatigue.

• Speed is the ability to perform a movement quickly. Athletes need speed to accelerate, change direction and react quickly to changes in the play.

• Flexibility is the ability to move a joint through its full range of movement without experiencing any pain or discomfort. Increased flexibility will allow the athlete to maximize improvements in endurance, strength and speed.

• Through improving each of the components of fitness, a number of sports specific factors are developed - strength endurance, speed endurance and power.

• Power is a combination of strength and speed.

• Coordination is the ability to move two or more body parts under control, smoothly and efficiently. Coordination tests are not commonly used in a fitness test battery. Coordination is a complex skill that requires good levels of other fitness components such as balance, strength and agility. On a sporting field, someone who appears to be well coordinated may also be displaying good timing.

• Agility relates to the ability to rapidly change the position of the entire body in space with speed and accuracy.

• Body composition is often included as a component of fitness. Body composition refers to the relative amount of muscle, fat, bone, and other vital parts that make up the body.

• Cardiorespiratory endurance involves the ability of the heart and lungs to supply oxygen to the working muscles for an extended period of time. It is also called aerobic endurance or aerobic fitness, which is the ability of the cardiovascular and respiratory systems to adjust to and recover from the effects of vigorous physical activity.