Sports Biology

course outline

In this course you will be expected to learn the following Introduction to structure and functioning of the following body systems

1. Skeletal system
2. Muscular system
3. Circulatory system
4. Respiratory system
5. Digestive system
6. Nervous system
7. Endocrine system

You will also be expected to demonstrate a knowledge of the following

1. Introduction to sports nutrition
2. Introduction to physical fitness
3. Introduction to sports injuries
4. Drugs used in sports

Skeletal system

An adult human skeleton is made up of 206 bones but are more at an early age.

The main bones of the human skeleton

The Skull - Cranium, Mandible and Maxilla

Shoulder girdle - clavicle and scapula

Arm - humerus, radius and ulna

Hand - Carpals, Metacarpals and Phalanges

Chest - Sternum and Ribs

Spine - Cervical area (top 7 vertibrae),Thoracic (next 12), Lumbar (bottom 5 vertebrae),Sacrum (5 fused or stuck together bones) and Coccyx (the tiny bit at the bottom of the spine)

Pelvic girdle - Ilium, Pubis and Ischium

Leg - Femur, Tibia and Fibula

Ankle - Talus and calcaneus (not shown above)

Foot - Tarsals, Metatarsals and Phalanges

Functions of the skeleton

The skeleton performs the following functions

• Support

The skeleton provides the framework which supports the body, and maintains its shape. The joints between bones permit movement,producing different range of movements e.g. the ball and socket joint allows a greater range of movement than the pivot joint at the neck.

• Movement

Movement in vertebrates is powered by skeletal muscles, which are attached to the skeleton by tendons. Without the skeleton to give leverage, movement would be greatly restricted.

• Protection

The skeleton protects many vital organs:

1. The skull protects the brain, the eyes, and the middle and inner ears.
2. The spine protects the spinal cord.
3. The rib cage, spine, and sternum protect the lungs, heart and major blood vessels.
4. The clavicle and scapula protect the shoulder.
5. The ilium and spine protect the digestive and urogenital systems and the hip.
6. The patella and the ulna protect the knee and the elbow respectively.
7. The carpals and tarsals protect the wrist and ankle respectively.

• Blood cell production

The skeleton is the site of haematopoiesis, which takes place in red bone marrow.

• Storage

Bone matrix can store calcium and is involved in calcium metabolism, and bone marrow can store iron in ferritin and is involved in iron metabolism

Effects of exercise on the skeletal system

The condition of bone may be improved by exercise as it responds to mechanical stresses. These mechanical stresses usually take the form of skeletal muscle pulling at their points of attachment being their origins and insertions. Where these mechanical stresses are applied, most it has been shown that more mineral salts are deposited and more collagenous fibres are produced. Therefore, both the density and size of bone in these areas may be increased and these changes in bone structure are stimulated by increased loads being placed on the skeleton. This has been borne out by greater bone mass being observed in weight lifters than in other lighter endurance athletes such as joggers. Other examples include racquet players who have been shown to have greater bone density in their playing arms. It has even been shown that if a leg is immobilised by being placed in plaster, due to a fracture, that even after a few weeks the bone becomes decalcified from lack of mechanical stress.

Whilst it may therefore be considered beneficial to utilise exercise to maintain healthy bones, great care must be taken with children whose bones and muscles are still developing. They should not be subjected to forms of sport involving high degrees of mechanical stress, partly because of the weaknesses that still exist within the bones, and also because of adverse effects on the development of these bones before maturity.

There are two main effects on bones as we grow older. Bones begin to lose calcium and this is one of the factors contributing to the condition called osteoporosis. Secondly, with age less protein is produced which alters the make-up of bone and sometimes creates brittle bones.

muscular system

Types of Muscle found in the body

There are three types of muscle found in the human body:

1. Skeletal Muscle
2. Smooth Muscle
3. Cardiac Muscle
4. Skeletal muscle

Skeletal Muscle Skeletal Muscles are those which attach to bones and have the main function of contracting to facilitate movement of our skeletons. They are also sometimes known as striated muscles due to their appearance. The cause of this 'stripy' appearance is the bands of Actin and Myosin which form the Sarcomere, found within the Myofibrils. Skeletal muscles are also sometimes called voluntary muscles, because we have direct control over them through nervous impulses from our brains sending messages to the muscle. Contractions can vary to produce powerful, fast movements or small precision actions. Skeletal muscles also have the ability to stretch or contract and still return to their original shape. Skeletal muscle fibre type Not all fibres within Skeletal muscles are the same. Different fibre types contract at different speeds, and are suited to different types of activity and vary in colour depending on their Myoglobin (an oxygen carrying protein) content.

Smooth muscle Smooth muscle is also sometimes known as Involuntary muscle due to our inability to control its movements, or Unstriated as it does not have the stripy appearance of Skeletal muscle. Smooth muscle is found in the walls of hollow organs such as the Stomach, Oesophagus, Bronchi and in the walls of blood vessels. This muscle type is stimulated by involuntary neurogenic impulses and has slow, rhythmical contractions used in controlling internal organs, for example, moving food along the Oesophagus or contricting blood vessels during Vasoconstriction.

Cardiac muscle This type of muscle is found solely in the walls of the heart. It has similarities with skeletal muscles in that it is striated and with smooth muscles in that its contractions are not under conscious control. However this type of muscle is highly specialised. It is under the control of the autonomic nervous system, however, even without a nervous imput contractions can occur due to cells called pacemaker cells. Cardiac muscle is highly resistant to fatigue due to the presence of a large number of mitochondria, myoglobin and a good blood supply allowing continuous aerobic metabolism.

circulatory system

components

The circulatory system consists of:

• The Heart,
• Arteries,
• Arterioles,
• Capillaries,
• Venules,
• Veins
• Blood

Anatomy of the heart

The heart consists of four chambers and is divided into left and right by a wall of muscle called the septum. The right side of the heart consists of an atrium which receives blood returning from the body, and the right ventricle, which then pumps blood out to the lungs, via the pulmonary artery. The left side again contains an atrium and a ventricle. The left atrium receives the oxygenated blood returning from the lungs and the ventricle then pumps this blood around the body. Due to the distance which the blood being pumped from the left ventricle has to travel, a more forceful contraction is required. For this reason the muscular wall of the left side is thicker than that of the right side. The atria and ventricles are separated by valves known as Atrioventricular, or AV valves. The purpose of these valves is to prevent blood from flowing in the wrong direction. Following the movement of blood from the atrium, into the ventricle, the AV valve snaps shut which causes the first heart sound of the heart beat (often described “lub dub”, with the closing of the AV valves being the “lub”) The “dub” sound is caused by the closing of two other valves, known as the Semilunar or SL valves. These are located between each ventricle and the artery leaving the heart, and again prevent the blood flowing backwards.

Functions of the circulatory system

The function of the circulatory system is to transport blood around the body.

1. Blood itself carries numerous substances which the body requires to function. The main one being Oxygen, carried by a protein called haemoglobin, found inside red blood cells.
2. White blood cells are also vital in their role of fighting disease and infection.
3. Blood contains platelets which are essential for clotting the blood, which occurs following an injury to stop blood loss.
4. Blood also carries waste products, such as Carbon Dioxide away from muscles and organs in order to be dispelled by the lungs.
5. Blood also distributes heat generated from the liver and muscles during contraction

Systemic circulation

At the start of the circulatory cycle the heart pumps oxygenated blood out of the left ventricle, through the Aorta (the largest artery in the body). The aorta divides into smaller arteries, then arterioles and finally into microscopic capillaries, found deep within muscles and organs. Here the Oxygen (and other nutrients) passes through the thin capillary walls, into the tissues where it can be used to produce the energy muscles require to contract. A waste product of energy production (metabolism) is Carbon dioxide and in order to be removed, it too passes across the walls of the capillaries, into the blood stream. The blood continues back towards the heart, through venules and then veins, into the right atrium.

Pulmonary circulation

Once blood returns to the heart it is then pumped from the right ventricle through the Pulmonary arteries to the lungs, where the waste carbon dioxide can be expelled and more Oxygen collected. The Pulmonary vein carries oxygenated blood back to the left atrium of the heart, where the cycle starts again.

Effects of the heart on cardiovascular system

1. The supply of blood vessels to the heart will increase thereby lowering blood pressure and improving the functioning of the heart
2. Lowers the cholesterol levels in the blood helping to reduce the risk of arteries "furring up" and possible heart disease
3. The period needed for the heart rate to return to normal after exercise is reduced
4. The network of capillaries in a muscle will increase thereby increasing the supply of blood, oxygen and nutrients to the working muscle

Digestive system

Introduction

The digestive system consists of a large number of organs and processes with the combined functions of breaking down our food into smaller molecules which can be used to produce energy and for other nutritional purposes; and excreting the waste consumed and produced by the system.

Digestion essentially occurs in a series of tubes such as the Oesophogus and Intestines as food passes through the body. A number of other organs contribute to digestion by providing enzymes for the breakdown of food

Mouth

The mouth is the starting point of digestion. Here the process of chewing starts to break down food and enzymes such as salivary lipase and amylase also start to chemically break down the food.

Oesophagus

Once you swallow the food moves into the Oesophagus where continual waves of involuntary contraction of smooth muscles in a process known as peristalsis pushes the food into the stomach.

Stomach

The stomach has both a mechanical and a chemical function in digestion. The upper part of the smooth (involuntary) stomach muscle relaxes to allow a large volume of food to be stored. The lower muscle then contracts in a rhythmical manner in order to churn the food inside and mix it together with the gastric acid (mainly hydrochloric acid) and digestive enzymes Pepsin, The stomach must then empty its contents into the small intestine.

Duodenum and small intestines

Whilst in the small intestine food is subjected to yet more enzymes, those from the Pancreas and from the glands within the intestine walls which break down carbohydrates and proteins. It is also mixed with a product of the liver which is stored and released into the intestine by the gall bladder. This is commonly known as bile. Bile works to dissolve fat so that it can be digested by the other enzymes. Rhythmic smooth muscle contraction continues within the small intestine and pushes the digesting food through its narrow tube.

Once the food is completely broken down into its individual components it is absorbed through the intestinal walls, into the blood flow of the capillaries which surround the intestine. To make this process faster and more efficient the intestinal walls contain numerous folds which are covered in finger-like projections called villi. This vastly increases the surface area of the intestine wall for molecules of digested food to pass through.

Large Intestine

The large intestine continues the foods journey and is the bodies last chance to absorb any water and minerals still remaining. The rest of the contents of the large intestine is waste such as undigestable pieces of food and fiber. This is passed through to the rectum where it is stored until you go to the toilet!

Nervous system

The nervous system is a network of specialized cells that communicate information about an organism's surroundings and itself. It processes this information and causes reactions in other parts of the body. It is composed of neurons and other specialized cells called glial cells (plural form glia) that aid in the function of the neurons. The nervous system is divided broadly into two categories: the peripheral nervous system and the central nervous system. Neurons generate and conduct impulses between and within the two systems. The peripheral nervous system is composed of sensory neurons and the neurons that connect them to the nerve cord, spinal cord and brain, which make up the central nervous system. In response to stimuli, sensory neurons generate and propagate signals to the central nervous system which then processes and conducts signals back to the muscles and glands. The neurons of the nervous systems of animals are interconnected in complex arrangements and use electrochemical signals and neurotransmitters to transmit impulses from one neuron to the next. The interaction of the different neurons form neural circuits regulate an organism's perception of the world and what is going on with its body, thus regulating its behavior. Nervous systems are found in many multicellular animals but differ greatly in complexity between species. more

Introduction to physical fitness

Activity

What is meant by the term physical fitness Explain the components of physical fitness