Despite making his debut in one of the most challenging North American rally events, 17-year-old Fraser McConnell had an electrifying start to Canadian motorsport which saw him place a sensational 11th place in the national standings, at the North America Tall Pines recently.It was the teen’s second rally as a young driver.Co-driving for the Jamaican was the very experienced Nathalie Richard who helped the teen to third overall, first in class production in two-wheel drive, first in novice and 11th place in the national standings.Co-driver Richard remarked of McConnell’s exploits: “For his first rally he chose the most challenging event in North America (Canada), Tall Pines. He did a great job and impressed me right from shakedown, which was his first time sitting in a car.”I was almost as proud of him as his supportive (but freezing) family members! Good stuff, Fraser!” she added, describing Rally of the Tall Pines as one of the most challenging annual events of the Canadian Rally Championship series.A total of four classes of cars in the order of speed/power: four-wheel drive open, four- wheel drive production, two-wheel drive open, and two-wheel drive production.The registered competitors faced off for National and/or Regional points and drivers were classified as ‘Expert’ or ‘Novice’.McConnell, who is currently a high school student in Canada, remains upbeat as he eyes a great future in the sport.”It’s a new experience for me. Good learning experience with a new car and new navigator.”Throughout the day I got faster and faster. It was quite a challenge, but what was exciting for me is that I was beating turbo four-wheel drive and open class,” the teen recalled.He added: “It was like the biggest event in the world for me and I just wanted to make my name. I will be trying to compete more abroad next year and get more power in the car,” said the 17-year-old.”Meanwhile, father Peter McConnell said: “We were torn about this decision because it coincided with Rally Jamaica, but we felt that he had much more to gain by competing in one of North America’s premier rally events.”With Fraser now introduced to the North American Rally World in a big way, he will no doubt be able make an even positive impact next time and chart a way forward.
Kidneys and homestasis The kidneys play many vital roles in homeostasis. They filter all the blood in the body many times each day and produce a total of about 1.5 litres of urine. The kidneys control the amount of water, ions and other substances in the blood by excreting more or less of them in urine. The kidneys also secrete hormones that help maintain homeostasis. The kidneys themselves are also regulated by hormones. For example, antidiuretic hormone from the hypothalamus stimulates the kidneys to produce more concentrated urine when the body is low on water. This process is known as osmoregulation. If you exercise on a hot day, you are likely to lose a lot of water in sweat. Then, for the next several hours, you may notice that you do not pass urine as often as normal and that your urine is darker than usual. This happens because your body is low on water and trying to reduce the amount of water lost in urine. The amount of water the body loses in urine is controlled by the kidneys, the main organs of the excretory system. Excretion is the process of removing waste and excess water from the body. It is one of the major ways the body maintains homeostasis (the process of maintaining a stable internal environment). Although the kidneys are the main organs of excretion, several other organs also excrete waste. They include the large intestine, liver, skin and lungs. All of these organs of excretion, along with the kidneys, make up the excretory system. The focus will be on the role of the kidneys in excretion. The roles of the other excretory organs are summarised below: – The large intestine eliminates solid waste that remains after the digestion of food. – The liver breaks down excess amino acids and toxins in the blood. – The skin eliminates excess water and salts in sweat. – The lungs exhale water vapour and carbon dioxide. The kidneys are part of the urinary system, which is shown above. The main function of the urinary system is to filter waste products and excess water from the blood and excrete them from the body. The kidneys are a pair of bean-shaped organs just above the waist. A cross section of a kidney is shown in the diagram above. The function of the kidney is to filter blood and form urine. Urine is the liquid waste product of the body that is excreted by the urinary system. Nephrons are the structural and functional units of the kidneys. A single kidney may have more than a million nephrons. Each kidney is supplied by a renal artery and a renal vein. As shown in figure above, each nephron is like a tiny filtering plant. It filters blood and forms urine in the following steps: 1. Blood enters the kidney through the renal artery, which branches into capillaries. When blood passes through capillaries of a nephron, blood pressure forces some of the water and dissolved substances in the blood to cross the capillary walls into the Bowman’s capsule. 2. The filtered substances pass to the renal tubule of the nephron. In the renal tubule, some of the filtered substances are reabsorbed and returned to the bloodstream. Other substances are secreted into the fluid. 3. The fluid passes to a collecting duct, which reabsorbs some of the water and returns it to the bloodstream. The fluid that remains in the collecting duct is urine. From the collecting ducts of the kidneys, urine enters the ureters, two muscular tubes that move the urine by peristalsis to the bladder. The bladder is a hollow, sac-like organ that stores urine. When the bladder is about half full, it sends a nerve impulse to a sphincter to relax and let urine flow out of the bladder and into the urethra. The urethra is a muscular tube that carries urine out of the body. Urine leaves the body through another sphincter in the process of urination. This sphincter and the process of urination are normally under conscious control.
When a prime mover contracts, the antagonist muscle will keep some fibres contracting to exert a ‘braking’ influence to stop the prime mover moving the joint so hard that the antagonist are damaged. Sometimes this system fails, for example, when a sprinter is running flat out, he may tear the hamstring and quickly come to a painful stop. The muscles we use depend on the activity, whether it requires muscles in the upper body or lower body to work together for short periods, or both at different phases of the activity, or most of the muscles of the body vigorously for longer periods (wrestling). All muscles contract and develop tension. However, the type of resistance the muscles meet will determine the type of muscle action. There are three main types of muscle contractions: – Isotonic concentric the muscles shorten as they contract and the ends of the muscle moves closer together e.g.; the biceps when doing pull ups. Most sporting movements are of this type. – Isotonic eccentric the muscles lengthen as they contract under tension, the ends of the muscles move further apart. e.g. the bicep works in this way when the body is lowered from pull-up position. – Isometric contraction the muscles stay the same length as they contract, there is no movement so the ends of the muscle stay the same distance apart. Shoulder muscles work in this way during the tug-o-war activity and the stabilising muscles that hold parts of the body steady as other parts move in many sporting movements. When we perform sporting activities we move our limbs in many different directions to affect the type of movements needed to execute various skills. Special words are used to describe the movements: – Extension The limbs straighten at the joint, eg, reaching to catch a ball (netball) – Flexion The limbs bend at the joint, eg, bending the trail leg at the knee when clearing hurdles. – Abduction The limbs move away from the midline of the body. – Adduction The limbs move towards the midline of the body – Rotation Circular movement. Part of the body turns while the rest remain still, E.g. rotation of the hip to play a shot in golf. – Circumduction- The end of a bone move in a circle, e.g., bowling in cricket – Inversion A lifting of the medial border of the arch combines with a medial bending of the front of the foot. – Eversion A slight rising of the lateral border of the foot combines with a slight lateral bending of the front of the foot. – Pronation Rotation of the forearm so that the palm turns medially. – Supination Rotation of the forearm so that the palm turns laterally. Every movement that takes place in the body depends on muscles. They work by contracting. The cardiac muscles in the heart contracts to pump blood out of the heart. Involuntary muscles in the artery walls contract to squirt the blood along and voluntary muscles which will be the main focus work when needed. A voluntary skeletal muscle contains nerves, which carry messages to and from the brain. Therefore, a muscle contracts when messages from the brain race along the nerve fibres, telling them to contract. It relaxes when the messages tell the fibres to lengthen again. Muscles work in pairs or groups. They have to work in pairs because muscles can only pull, they can’t push. For example, the biceps and triceps work together to execute the arm curl movement. To flex the arm, the biceps contract and the triceps relax. To straighten it, the triceps contract and the biceps relax. Large numbers of pairs of muscles are needed to work together in the different ways for even simple body movements. The muscles take on different roles, depending on the movement that is performed. They can work as: – Flexors contracting to bend a joint – Extensors contracting to straighten a joint – Prime movers or agonist contracting to start a movement (biceps muscles perform this role in arm curl) – Antagonist relaxing to allow the movement to take place (the triceps muscles perform this role in arm curl) The biceps and triceps will swap places as the prime mover and antagonist when arm is straightened. – Fixators contracting to steady parts of the body to give the working muscles a firm base. (the deltoid perform this role in the arm curl) – Synergist reducing unnecessary movement when a prime mover contracts. They can also fine tune the movement (the brachialis in the forearm performs this role in the arm curl) PAINFUL STOP