THE HUMAN SKELETON 29 MAY 2013

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1 THE HUMN SKELETON 29 MY 2013 Lesson escription In this lesson we: iscuss important terminology Look at the axial skeleton & the appendicular skeleton iscuss the functions of the skeleton Work through a revision question Key oncepts Terminology appendicular skeleton exoskeleton thorax axial skeleton ligament sternum cranium tendon vertebral column chitin pectoral girdle vertebrae endoskeleton pelvic girdle The Structure of the Human Skeleton Humans are vertebrates and contain an endoskeleton. The human skeleton consists of 206 bones. The largest bone is the thigh bone called the femur, and the smallest is the stirrup of the middle ear. Most mammals move on four legs. Humans are bipedal, which means that they stand upright in two legs and use only their legs for locomotion. This frees their arms and hands, which can be used to do other things. The endoskeleton of humans consists of two parts: The axial skeleton is the main, longitudinal part of the skeleton. It consists of the skull, vertebral column and rib cage. The appendicular skeleton refers to the parts of the skeleton that are attached to the axial skeleton. It includes the pectoral girdle, the pelvic girdle, and the bones of the arms and legs The xial Skeleton The axial skeleton is the main, longitudinal part of the skeleton. It consists of the skull, vertebral column and rib cage. The Skull The skull is that part of the skeleton that forms your head. The skull consists of two parts, a brain box called the cranium and the facial parts. The cranium consists of flat bones that fit together with zigzag joints called sutures. The facial parts consist of the nasal bones, eye socket, upper jaw and lower jaw.

2 The facial parts are joined to the cranium by: Sutures in the front of the skull The cheekbone on each side of the skull. Underneath the skull is a hole known as the foramen magnum through which the spinal cord passes. In humans and animals that are bipedal, the skull is positioned on the top of the vertical spinal column. In four legged mammals that walk on all four limbs, the foramen magnum is behind the skull as the spinal column leaves the back of the skull and is horizontal. The skull has two jaw bones. The upper jaw bone (maxilla) cannot move because it is fixed to the skull. The lower jaw (mandible) is joined to the skull near the ear. The lower jaw can move up and down and sideways. oth the upper jaw and lower jaws have teeth. The roof of the mouth is called the palate. It separates the mouth from the nasal passages above it. This allows us to breathe while we are chewing our food. In grade 12 you will study the human evolution and find out how the facial bones, cranium, foramen magnum, palate and jaws have changed as humans have evolved. The different types of teeth in Mammals: ll mammals have two sets of teeth during their lifetime: a temporary milk set and a permanent set. Humans have 20 milk set of teeth and 32 permanent teeth. The teeth are symmetrically arranged in both the upper and lower jaws. hewing is the main purpose of teeth in humans and there are four types, each of which has its own function. Incisors - cut food into small pieces anines help to hold and tear or bite food Premolars and molars compress and grind food into fine particles The Vertebral olumn The vertebral column is also commonly called the spinal column or the backbone. The irregular bones are called the vertebrae and there are 33. They are connected so that a flexible, curved structure is formed. The vertebral column goes from the skull to the pelvis and forms the central axis of the body. It surrounds and protects the delicate spinal cord, which runs through its central cavity. It is also a point of attachment for the ribs, the pectoral girdle and the pelvic girdle.

3 The Rib age: Twelve pairs of ribs, the sternum (breastbone) and the thoracic vertebrae form the bony rib cage known as the thorax or chest.

4 The ppendicular Skeleton The word appendicular means connected to. The appendicular skeleton refers to the parts of the skeleton that are attached to the axial skeleton. It includes the pectoral girdle, the pelvic girdle, and the bones of the arms and legs. The Pectoral Girdle The bones in the pectoral (shoulder) girdle connect the bones of the arm to the forearm, the wrist and the hands to the axial skeleton of the thorax. The Pelvic Girdle The pelvic (hip) girdle connects the bones of the leg, the ankle and the foot to the axial skeleton of the pelvis.

5 The Functions of the Human Skeleton The general functions of the human skeleton are: Movement with the muscles, it is important for movement(locomotion) Protection it provides delicate or sensitive parts of the body(e.g. the skull protects the brain and the ribs protect the heart and lungs) Support it gives the body support, strength and shape Storage it stores minerals salts Hearing it helps in hearing, through the smallest bones in the ear, the ossicles Formation it is the site for the formation of red blood corpuscles. Questions Question 1 hoose the correct answer and write the correct letter corresponding to the correct answer in the table below (failure to do so will result in you losing marks): Question Number: Total 4 x 2 = [8] nswer 1.1 The bones of the hand are called the: phalanges. metacarpals. carpals. tarsals. 1.2 Which of the following joins bone to bone? tendons. ligaments. cartilage. muscle. 1.3 The tough membrane surrounding every muscle is called the: epimysium. perimysium. sarcomere. myofibril.

6 1.4 The disease that causes the cartilage to wear away at the joints and resulted in Mr Lambson having a hip replacement is called: osteoporosis. rheumatoid arthritis. old age osteoarthritis. Question 2 Write down the correct biological term for the following descriptions in the spaces provided. Number escription iological Term a.) skeleton made up of a fluid filled cavity. b.) The skeleton that consists of two girdles and their associated limbs. c.) disease caused by a lack of vitamin. d.) The vertebrae found in the upper back. e.) The head of the long bone. f.) The type of joint that is unable to move. g.) h.) The end of the muscle that is attached to the part that can move. medical doctor who specialises in injuries of the skeleton. 8 1 = [8] Question 3 a.) In the space below draw a table that compares the advantages of an exoskeleton and an endoskeleton. You need to give two advantages of each skeleton. (6) b.) Give a heading for your table: (2) [8]

7 Question 4 Study the diagram of the human skeleton below and answer the questions that follow: a.) Provide labels for the following bones: 2: 4: 8: 10: 17: b.) Give the numbers of three bones that are part of the axial skeleton. (3) c.) Give the number and name of the calf bone. (2) d.) What evidence from the diagram above would you use to explain why the skeleton above is of a male? (3) [13] Links (5) Magnification simulation nimal / Plant ell: 3 animation of a cell: Reference List 1. Via frika Life Sciences; Grade 10 Learner s ook; M. owie,. Johannes, R. Mhlongo, E. Pretorius. 2. Shuters Top lass Life Sciences Grade 10 Learners ook; P. yerst, R. Langely, P. Majozi,. Metherell,. Smith. 3. Spot On, Life Sciences Learners ook, awson, P Holm, G Jackson; H Skinner 4. Oxford Successful Life Sciences Learner s ook, W. ezuidenhout, lark, S opley, rew, R Engelbrecht; J Goliath