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Download The skeleton and Muscles - Ms Curran`s Leaving Certificate Biology
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The Skeletal System Skeletal and muscle systems work together and are controlled by our nervous system 3 types of muscle 1. Skeletal muscle associated with the skeleton it tires easily (open and close your fist for 2 minutes!) This muscle is under conscious control - voluntary 2. Smooth muscle – also called unstriped or involuntary muscle Found internally in digestive system, bladder, blood vessels, uterus etc. Contracts slowly Slow to tire Not under conscious control 3. Cardiac muscle Found in the heart Involuntary Contracts strongly Does not tire Types of Skeleton Exoskeleton – skeleton on the outside Eg. Insects Endoskeleton – skeleton on the inside Eg. Humans What type of skeleton is in each of the following?? Lobster Rabbit Elephant Beetle Crab Fish Answers Lobster - Exoskeleton Rabbit – Endoskeleton Elephant - Endoskeleton Beetle - Exoskeleton Crab - Exoskeleton Fish - Endoskeleton Functions of the skeleton 1. 2. 3. 4. 5. Support Shape Protection Movement Manufacture of blood components Support Skelton provides a rigid frame to hold body upright Shape Person with long bones will be tall Bones in the foot determine the width of the foot etc Protection Skull protects brain Spine protects spinal chord Ribs protect heart + lungs Movement Bones act as rigid levers against which muscles pull Manufacture of blood components Bone marrow makes red blood cells, white blood cells and platelets Structure of the skeleton 213 bones in total Divided into Axial and Appendicular skeleton Axial skeleton Consists of Skull , Spine, ribs and sternum Skull Also called the cranium Consists of 22 bones Most are fused together Lower jaw moves to allow mouth to open and close Spine Made of 33 bones called vertebrae These are arranged into 5 regions Top 24 vertebrae are held together by ligaments and can move slightly They are separated by discs of cartilage Discs of Cartilage Have a hard outer layer with a soft jelly like centre They act as shock absorbers and protect the vertebrae A Slipped Disc Sometimes soft centre bulges out and compresses spinal nerves People are taller in the morning as their discs are fully expanded During the day discs become compressed due to gravity and people are shorter in the evening Vertebra Shape Vertebra have different shapes depending on where they are General structure Rib Cage Consists of Sternum, Breastbone and 12 pairs of ribs Ribs 1-7 are connected to the breastbone and are called true ribs Ribs 8 – 10 are attached to each other at the front of the chest by cartilage they are called False ribs Ribs 11 -12 are only attached to the spine they are called floating ribs The Appendicular Skeleton Consists of limbs (arms + legs), the pectoral (shoulder) girdle, and the pelvic (hip) girdle Pectoral girdle Consists of the collar bone (clavicle) and shoulder blade (scapula) Forms a connection with the vertebral column and the arms (ie. The humerus, radius, ulna, carpals, metacarpals and digits which contain the phalanges) Pelvic Girdle 2 halves joined at the front by cartilage Each half has 3 fused bones Pelvic girdle fused to spine at sacrum Hip bones attach to sacrum at pelvis Hip bones, Sacrum + legs make pelvic girdle Legs Consists of femur, patella, fibula, tibia, tarsals, metatarsals, digits which contain philanges Limbs Arms and legs have similar design patterns Each limb ends in 5 digits for this reason they are known as Pentadactyl limbs Phalanges The bones in fingers and toes Each finger and toe has three phalanges Exceptions are the thumb and big toe which only have two Important feature of Great apes and humans is that we have opposable thumbs which gives great powers of manipulation "Well, there it goes again ... and here we just sit without opposable thumbs." Structure of long bone Enclosed by a membrane called periosteum This membrane contains blood vessels and nerves Long shaft of bone is called the diaphysis The head of the bone is the epiphysis Cartilage Cartilage contains a firm, flexible protein called collagen Collagen fibres are embedded in a matrix of calcium and phosphorous salts There are no blood vessels and nerves here For transport cartilage depends on materials diffusing through to the cells that form it For this reason cartilage is slower to heal than bone Cartilage is found in the pinna of the ear, the nose, trachea, and in between vertebra It also covers the end of bones to protect bones and reduce friction 3 types of bone Compact bone Spongy bone Bone marrow Compact bone Made of osteoblasts (bone cells) embedded in a matrix of 70% inorganic (non living) materials and 30% collagen Blood vessels and nerve fibres are found here Bone cells and collagen are organic (living) Compact bone is found in the diaphysis of the bone and at the ends of a bone Spongy Bone Like compact bone that contains lots of hollows (like aero chocolate) Spaces in spongy bone are filled with red bone marrow that makes red blood cells Mainly found in epiphysis Bone marrow Soft fatty substance found in medullary cavity and in spongy bone Full and active red marrow in young people Active marrow confined to spongy bone in adults Medullary cavity of adults contains inactive, yellow fat rich marrow This can convert to red marrow if needed Bone Growth By the seventh week of embryonic life the skeleton begins to turn from cartilage to bone. This is called ossification Bone Growth Cartilage at joint Epiphysis Spongy bone Epiphysis plate Compact/hard bone Diaphysis Marrow Periostium Epiphysis plate Epiphysis Cartilage At birth, all cartilage has been converted to bone except at the joints and internally at the end of the epiphysis along the epiphysis plate. Bone Growth During growth, osteoblasts at the edge of the growth plate convert the cartilage to bone and new cartilage is formed by mitosis within the growth plate. The growth plate is pushed further into the epiphysis as the bone lengthens. Growth continues until the growth plate is fully calcified. Bone Growth There are three periods of rapid growth in human development: 1. during the final trimester of pregnancy the foetus doubles in size. 3. during puberty. Growth spurt at puberty Mass/kg 2. during the first two years after birth and Growth spurt after birth Growth slows after puberty and stops at age 24 approx. when the epiphysis plate is fully calcified Time/Years Birth Growth Curve in Humans Adult height cannot be increased beyond that which is genetically determined, even by increasing nutrition. Renewal of Bones Dependant on physical activity, hormones and diet Physical activity Bones stressed by physical activity become thicker and stronger Lack of stress on bones causes them to become thin – a problem for astronauts in weightlessness Hormones Growth hormones + sex hormones increase the size of bones this is clearly seen in puberty Parathormone removes calcium from bone to raise calcium levels in blood Diet It is essential to have calcium in the diet Osteoporosis This is the loss of the protein collagen from bone Bones become brittle and easily broken Joints Where two or more bones meet Name 3 such places in the body Different types of joints are classified depending on the movement they allow How much movement do the joints you have named allow? Immovable Fixed or fused joints eg. Skull + Pelvic girdle Slightly moveable Joints between vertebrae in upper spinal column are slightly moveable Bones are separated by pads of cartilage Bones are held in place by ligaments to restrict amount of movement this protects spinal chord Freely moveable (Synovial) Synovial joints are found in the knee, hip, elbow and shoulder Ends of bones are covered with cartilage and bones are separated by a cavity Bones are held in place by ligaments Synovial Membrane Synovial membrane encloses the joint It secretes synovial fluid Synovial fluid lubricates joint and reduces friction Entire joint enclosed in a protective capsule Swollen Joints In injury synovial membrane secretes more fluid and joint swells Treatment summarised by the word RICE (Rest, Ice, Compression, Elevation) Hinge joints, Elbow and Knee, movement in one direction only Ball and socket joints, hip and shoulder, allow movement in all directions Antagonistic pairs Ligaments Connect bone to bone Strong, fibrous, and slightly elastic Ligaments are more flexible when warm this is why you warm up before exercise Tendons Connect muscles to bone Strong, flexible and inelastic Mostly composed of collagen some have blood vessels Musculoskeletal Disorder Arthritis
