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Home , Human skeleton

Skeletal system fact sheet

• At birth the human is made up of around 300 . By adulthood, some bones have fused together to end up with 206 bones. • Human bones grow continually from birth till our mid 20's. Our skeleton's mass is at its maximum density around the age of 30. • If broken our bones will re-grow and repair themselves. Often doctors will place a cast on splint to make sure these bones repair straight and true. • The part of the human skeleton has 80 bones. It includes the , the cage and the and helps us maintain our upright posture, by spreading the weight in the head, and upper areas down to the lower areas near the . • The appendicular skeletal section of our skeleton has 126 bones. It includes the pectoral (shoulder) girdles, the pelvic girdle and the bones of the lower and upper limbs. Its function is for movement of the body and to protect some organs. • The human skeletal system has six major functions including the production of blood cells, for support, for movement, for protection, for storage of ions and endocrine regulation. • The longest bone in the is the thigh bone called the . • The smallest bone found in the human body is located in the middle . The staples (or stirrup) bone is only 2.8 millimetres (0.11 inches) long. • Like our skin, the human body's bones are also constantly worn down and re-made, to the point where every 7 years we essentially have a new bone. • The area of our body with the most bones is the , fingers and wrist where there are 54 bones. • Our teeth form part of the skeletal system, but are not counted as bones. • There a just a few differences between human male and female . The female skeleton is generally slightly smaller and the bones differ in shape, size and angle in order to assist with child birth. • The majority of human bones have a dense, strong outer layer, followed by a spongy part full of air for lightness, while the middle contains a soft, flexible, tissue substance called . • Bone marrow makes up 4% of a human body mass. It produces red blood cells which carry oxygen all over the body. Marrow is also produces , key components of the , which support the body's . • is very important for our bones and helps keep them strong and healthy. • The areas where our bones meet are called . The joints in our cranium have no movement while our joints allow for a wide range of movement. • Bones are held in place at joints by muscles and also tissues called ligaments. Another type of tissue called covers each bone surface area to prevent the bones rubbing. • The medical branch of learning about the human skeletal system is called Orthopedics. • There are a number of skeletal disorders, is a bone that increases the chance of fractures, is a curvature of the spine, while is an inflammatory disease that damages joints.

Muscular system fact sheet

• Muscle is a soft tissue in the body of humans and animals. Its main purpose is to produce force and motion. • Muscles are responsible for maintaining posture, physical movement (sitting, walking, eating, etc), and movement of internal organs (such as keeping the pumping to circulate blood and moving food through the digestive system). • The word muscle is derived from the Latin term musculus, meaning "little mouse". This Latin term could be due to the shape of some muscles or because muscles contracting under the skin can look like a mouse moving under a rug. • connect our soft contracting muscle to our hard bones. • There are around 650 skeletal muscles in the human body. • There are three types of muscle, skeletal, cardiac, and smooth. • Skeletal muscles (or striated) are voluntary muscles that control nearly every action a person intentionally performs. Tendons attach the muscle to two bones across a joint, as one muscle contracts the other relaxes which moves the bones. • can be further divided into two types, slow twitch and fast twitch. • Slow twitch (Type I) muscle contain proteins that give it a rich red colour. This muscle carries more oxygen efficiently and using fats, proteins or carbs as energy slow twitch muscle fibres contract over a long period of time. • Therefore type I muscle fibre works well for aerobic sports such as long distance running and cycling. • Fast twitch (Type II) muscle is whiter in colour as it has less myoglobin (a oxygen carrying protein). Fast twitch fibres contract quickly and powerfully, however they fatigue rapidly. • Therefore type II muscle fibre is useful for anaerobic exercise such as sprinting or for strength sports like weightlifting. • Smooth muscle (or visceral) is involuntary, its not controlled by our conscious mind. It is found on the walls of many organs and structures such as the oesophagus, , intestines, bladder, and blood vessels. Smooth muscles contract to move substances such as food through the . • Cardiac muscle is also an involuntary muscle. It is only found in the heart and is responsible for keeping the heart pumping. • Muscle makes up around half of the total human body weight. Muscle tissue is also around 15% denser than fat tissue. • It takes 17 muscles in the for us to smile and 43 muscles to frown. • If muscle strength is regarded as the ability to use force on something then the jaw muscle (masseter) is the strongest in the body. • The strongest muscles in relation to the job they have to do is the external muscles of the eye which are large and about 100 times stronger than they need to be in relation to the small size and weight of the eyeball. • The heart cardiac muscle does the most work of any muscle over a lifetime. • Cerebral palsy is a disorder that affects balance and motor functions, while muscular dystrophy is a genetic disease that damages muscle fibres. • Muscle memory is created by practising an action over and over again. Our muscles fine tune themselves, becoming more precise and exact in what they do. So practice is very important when learning a sport!!

Digestive system fact sheet

• The digestive system is responsible for breaking down food we eat into smaller components so that nutrients can be easily absorbed by the body and the waste discarded. • There are two types of digestion. Mechanical digestion is the physical breakdown of large pieces of food into smaller pieces through, chewing (mastication). While chemical digestion uses enzymes to break down this food mass further into small molecules which the body can separate and use. • Saliva in our mouths plays a key role in initial digestion by moistening the food to help with the mechanical chewing and swallowing process. Saliva also contains an enzyme which starts the chemical digestion of starchy foods. • Our salivary glands produce around 1.5 litres of saliva each day! • Bolus is the name of the small round slurry mass produced for swallowing as a result of chewing and starch digestion. • The , at the back of the throat, has a flap of tissue called the epiglottis that closes during swallowing to prevent food going down the (windpipe). • Once swallowed, bolus (food) travels down through the oesophagus to the stomach, taking about 7 seconds to get there. • Muscles in the oesophagus tighten and relax to create a wave-like process called peristalsis which pushes food down the small tube, which is why your food never falls back out if you happen to be eating and swallowing upside down! • Enzymes called proteases break down proteins within the stomach and . While in saliva, amylases break down carbohydrates and lipases break down fats. • The adult stomach has a very small volume when empty but can expand to hold up to 1.5 litres of food when full. • The inner wall of the stomach secretes hydrochloric acid to help kill bacteria and, along with proteases enzymes, aids in the digestion of food. To protect itself from the corrosive acid, the stomach lining must create a thick coating of mucus. • Stomach rumblings (borborygmi) are caused by wave-like muscular contractions (peristalsis) at the walls of the stomach and small intestine. These are normal digestion movements, however the process is louder and more noticeable when the stomach is empty as the sound is not muffled. • Some animals such as cows, giraffes and deer have stomachs with multiple compartments (not multiple stomachs as is commonly believed). While others like seahorses, lungfishes and platypuses have no stomachs at all. • The small intestine is composed of a duodenum, jejunum, and ileum. • Most of the digestion and absorption of food nutrients actually takes place in the small intestine. The stomach passes on a thick liquid called chyme and enzymes continue to break this down in the small intestine which absorbs the nutrients into the bloodstream. • The secretes enzymes for use by the small intestine. • On average, the human adult male's small intestine is 6.9 m (22 ft 6 in) long, and the female's 7.1 m (23 ft 4 in). • The includes the cecum, , colon, and . It is the final part of the digestive system. It absorbs water from the remaining indigestible food matter, and passes any un-needed waste from the body. • The large intestine is approximately 1.5 m (4.9 ft) long. • The produces bile for the digestive system and processes the nutrients. • The gall bladder stores the bile used to break down dietary fat