Lec_activity6_skeletal_system

NUR11O1 Integrated Human Anatomy and Physiology Department of Biology Institute of Arts and Sciences Far Eastern University

LECTURE ACTIVITIES NO. 6 SKELETAL SYSTEM Name: Yda Maxine Palma

Section: Section 17

Date Submitted: 10/31/2020

I. INTRODUCTION The skeletal system is a system which provides an internal framework for the human body, protects organs and anchors skeletal muscles so that muscle contraction can cause movement. The internal framework is mainly provided by the skeleton which is divided into two parts: axial skeleton which consists of bones that form the longitudinal axis of the body and the appendicular skeleton which forms the limbs and girdles. Bone is a living vascular structure composed of organic tissue and mineral. It serves as a support structure, site of attachment for skeletal muscles and site of blood cell formation. Bone is characterized by its hardness and strength. But despite its remarkable strength, it is susceptible to fracture or breaks. A type of fracture in which the bone breaks clearly but does not penetrate the skin is known as a closed fracture while if there is a communication with the skin it is known as an open fracture. II. ACCOMPLISH THE ACTIVITY TABLE 1. GUIDE QUESTIONS 6.01A. Explain the functions of the skeletal system.

ANSWERS Support. Rigid, strong bone is well suited for bearing weight and is the major supporting tissue of the body. Cartilage provides firm yet flexible support within certain structures, such as the nose, external ear, thoracic cage, and trachea. Ligaments are strong bands of fibrous connective tissue that attach to bones and hold them together. Protection. Bone is hard and protects the organs it surrounds. For example, the skull encloses and protects the brain, and the vertebrae surround the spinal cord. The rib cage protects the heart, lungs, and other organs of the thorax. Movement. Skeletal muscles attach to bones by tendons, which are strong bands of connective tissue. Contraction of the skeletal muscles moves the bones, producing body movements. Joints, where two or more bones come together, allow movement between bones.

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NUR11O1 Integrated Human Anatomy and Physiology Department of Biology Institute of Arts and Sciences Far Eastern University

6.02A. Describe the components of the extracellular matrix and explain the function of each.

Smooth cartilage covers the ends of bones within some joints, allowing the bones to move freely. Ligaments allow some movement between bones but prevent excessive movement. Storage. Some minerals in the blood—principally, calcium and phosphorus—are stored in bone. Should blood levels of these minerals decrease, the minerals are released from bone into the blood. Adipose tissue is also stored within bone cavities. If needed, the lipids are released into the blood and used by other tissues as a source of energy. Blood cell production. Many bones contain cavities filled with red bone marrow, which produces blood cells and platelets. The bone, cartilage, tendons, and ligaments of the skeletal system are all connective tissues. Their characteristics are largely determined by the composition of their extracellular matrix. The matrix always contains collagen, ground substance, and other organic molecules, as well as water and minerals. But the types and quantities of these substances differ in each type of connective tissue. Collagen is a tough, rope like protein. Proteoglycans are large molecules consisting of polysaccharides attached to core proteins, similar to the way needles of a pine tree are attached to the tree’s branches. The proteoglycans form large aggregates, much as pine branches combine to form a whole tree. Proteoglycans can attract and retain large amounts of water between their polysaccharide “needles.” The extracellular matrix of tendons and ligaments contains large amounts of collagen fibers, making these structures very tough, like ropes or cables. The extracellular matrix of cartilage contains collagen and proteoglycans. Collagen makes cartilage tough, whereas the water-filled proteoglycans make it smooth and resilient. As a result, cartilage is relatively rigid, but it springs back to its original shape after being bent or slightly compressed. It is an excellent shock absorber. The extracellular matrix of bone contains collagen and minerals, including calcium and phosphate. The rope like collagen fibers, like

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NUR11O1 Integrated Human Anatomy and Physiology Department of Biology Institute of Arts and Sciences Far Eastern University

6.03A. Explain the structural differences between compact bone and spongy bone.

6.03B. Outline the processes of bone ossification, growth, remodeling, and repair.

the reinforcing steel bars in concrete, lend flexible strength to the bone. The mineral component, like the concrete itself, gives the bone compression (weight-bearing) strength. Most of the mineral in bone is in the form of calcium phosphate crystals called hydroxyapatite. Compact bone has more bone matrix and less space due to osteons. Spongy bones have less bone matrix and more space due to trabeculae. Ossification 1. A cartilage model, with the general shape of the mature bone, is produced by chondrocytes. A perichondrium surrounds most of the cartilage model. 2. The chondrocytes enlarge, and cartilage is calcified. A bone collar is produced, and the perichondrium of the diaphysis becomes the periosteum. 3. A primary ossification center forms as blood vessels and osteoblasts invade the calcified cartilage. The osteoblasts lay down bone matrix, forming trabeculae. 4. Secondary ossification centers form in the epiphyses of long bones. Growth 1. New cartilage is produced on the epiphyseal side of the plate as the chondrocytes divide and form stacks of cells. 2. Chondrocytes mature and enlarge. 3. Matrix is calcified, and chondrocytes die. 4. The cartilage on the diaphyseal side of the plate is replaced by bone. Repair 1 Hematoma formation Blood released from damaged blood vessels forms a hematoma. 2 The internal callus forms between the ends of the bones, and the external callus forms a collar

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NUR11O1 Integrated Human Anatomy and Physiology Department of Biology Institute of Arts and Sciences Far Eastern University

6.04A. Explain the role of bone in calcium homeostasis.

6.04B. Describe how parathyroid hormone and calcitonin influence bone health and calcium homeostasis.

6.05A. List and define the major features of a typical bone.

6.06A. Name the bones of the skull and describe their main features as seen from the lateral, frontal, internal, and inferior views.

around the break. 3 Callus ossification Woven, spongy bone replaces the internal and external calluses. 4 Bone remodeling Compact bone replaces woven bone, and part of the internal callus is removed, restoring the medullary cavity. The bones act as a storage site for calcium: The body deposits calcium in the bones when blood levels get too high, and it releases calcium when blood levels drop too low. Parathyroid hormone increases blood calcium levels when they drop too low. Conversely, calcitonin, which is released from the thyroid gland, decreases blood calcium levels when they become too high. These two mechanisms constantly maintain blood calcium concentration at homeostasis. Anatomists use several common terms to describe the features of bones. For example, a hole in a bone is called a foramen. A foramen usually exists in a bone because some structure, such as a nerve or blood vessel, passes through the bone at that point. If the hole is elongated into a tunnel-like passage through the bone, it is called a canal or a meatus. A depression in a bone is called a fossa. A lump on a bone is called a tubercle or a tuberosity, and a projection from a bone is called a process. Most tubercles and processes are sites of muscle attachment on the bone. Increased muscle pull, as occurs when a person lifts weights to build up muscle mass, can increase the size of some tubercles. The smooth, rounded end of a bone, where it forms a joint with another bone, is called a condyle The skull consists of 22 bones: 8 forming the braincase and 14 facial bones. The hyoid bone and 6 auditory ossicles are associated with the

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NUR11O1 Integrated Human Anatomy and Physiology Department of Biology Institute of Arts and Sciences Far Eastern University

6.06B. List the bones that form the majority of the nasal septum.

6.06C. Describe the locations and functions of the paranasal sinuses.

6.06D. List the bones of the braincase and the face. 6.06E. Describe the shape of the vertebral column and list its divisions.

6.06F. Discuss the common features of the vertebrae and contrast vertebrae from each region of the vertebral column.

6.06G. List the bones and cartilage of the rib cage, including the three types of ribs.

skull. From a lateral view, the parietal, temporal, and sphenoid bones can be seen. From a frontal view, the orbits and nasal cavity can be seen, as well as associated bones and structures, such as the frontal bone, zygomatic bone, maxilla, and mandible. The interior of the cranial cavity contains three fossae with several foramina. The base of the skull reveals numerous foramina and other structures, such as processes for muscle attachment.  perpendicular plate of ethmoid bone.  vomer bone.  cartilage of the septum.  crest of the maxillary bone.  crest of the palatine bone. The sinuses are named for the bones where they are located and include the frontal, maxillary, ethmoidal, and sphenoidal sinuses. The skull has additional sinuses, called the mastoid air cells, which are located inside the mastoid processes of the temporal bone. These air cells open into the middle ear instead of into the nasal cavity. When viewed from the side, an adult spine has a natural S-shaped curve. And is divided into cervical, thoracic, lumbar, sacrum, and coccyx The vertebral column contains 7 cervical, 12 thoracic, and 5 lumbar vertebrae, plus 1 sacral bone and 1 coccyx bone. Each vertebra consists of a body, an arch, and processes. Regional differences in vertebrae are as follows: Cervical vertebrae have transverse foramina; thoracic vertebrae have long spinous processes and attachment sites for the ribs; lumbar vertebrae have rectangular transverse and spinous processes, and the position of their facets limits rotation; the sacrum is a single, fused bone; the coccyx is 4 or fewer fused vertebrae. The rib cage consists of the thoracic vertebrae, the ribs, and the sternum. There are 12 pairs of ribs: 7 true and 5 false (2 of the false ribs are also

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NUR11O1 Integrated Human Anatomy and Physiology Department of Biology Institute of Arts and Sciences Far Eastern University

6.07A. Identify the bones that makeup the pectoral girdle and relate their structure and arrangement to the function of the girdle. 6.07B. Name and describe the major bones of the upper limb.

6.07C. Name and describe the bones of the pelvic girdle and explain why the pelvic girdle is more stable than the pectoral girdle.

6.07D. Name the bones that make up the coxal bone. Distinguish between the male and female pelvis.

called floating ribs). The sternum consists of the manubrium, the body, and the xiphoid process. The pectoral girdle includes the scapulae and clavicles. The upper limb consists of the arm (humerus), forearm (ulna and radius), wrist (8 carpal bones), and hand (5 metacarpal bones, 3 phalanges in each finger, and 2 phalanges in the thumb). Unlike the bones of the pectoral girdle, which are highly mobile to enhance the range of upper limb movements, the bones of the pelvis are strongly united to each other to form a largely immobile, weight-bearing structure. This is important for stability because it enables the weight of the body to be easily transferred laterally from the vertebral column, through the pelvic girdle and hip joints, and into either lower limb whenever the other limb is not bearing weight. Thus, the immobility of the pelvis provides a strong foundation for the upper body as it rests on top of the mobile lower limbs. The pelvic girdle is made up of the 2 coxal bones. Each coxal bone consists of an ilium, an ischium, and a pubis. The coxal bones, sacrum, and coccyx form the pelvis. The differences between the adult female and male pelvis relate to function and body size. In general, the bones of the male pelvis are thicker and heavier, adapted for support of the male’s heavier physical build and stronger muscles. The greater sciatic notch of the male hip bone is narrower and deeper than the broader notch of females. Because the female pelvis is adapted for childbirth, it is wider than the male pelvis, as evidenced by the distance between the anterior superior iliac spines. The ischial tuberosities of females are also farther apart, which increases the size of the pelvic outlet. Because of this increased pelvic width, the subpubic angle is larger in females (greater than 80 degrees) than it is in males (less than 70 degrees). The female sacrum is wider, shorter, and less curved, and the sacral promontory projects less into the pelvic cavity, thus giving the

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NUR11O1 Integrated Human Anatomy and Physiology Department of Biology Institute of Arts and Sciences Far Eastern University

female pelvic inlet (pelvic brim) a more rounded or oval shape compared to males. The lesser pelvic cavity of females is also wider and shallower than the narrower, deeper, and tapering lesser pelvis of males. Because of the obvious differences between female and male hip bones, this is the one bone of the body that allows for the most accurate sex determination. 6.07E. Identify and describe the bones of the lower The lower limb includes the thigh (femur), leg (tibia and fibula), ankle (7 tarsal bones), and foot limb. (metatarsal bones and phalanges, similar to the bones in the hand). There are two ways to classify joints: on the basis 6.08A. Describe the two systems for classifying of their structure or on the basis of their function. joints. The structural classification divides joints into fibrous, cartilaginous, and synovial joints depending on the material composing the joint and the presence or absence of a cavity in the joint. The three types of fibrous joints are sutures, 6.08B. Explain the structure of a fibrous joint, list gomphoses, and syndesmoses. A suture is the the three types, and give examples of each type. narrow fibrous joint that unites most bones of the skull. At a gomphosis, the root of a tooth is anchored across a narrow gap by periodontal ligaments to the walls of its socket in the bony jaw. A syndesmosis is the type of fibrous joint found between parallel bones. The gap between the bones may be wide and filled with a fibrous interosseous membrane, or it may narrow with ligaments spanning between the bones. Syndesmoses are found between the bones of the forearm (radius and ulna) and the leg (tibia and fibula). Fibrous joints strongly unite adjacent bones and thus serve to provide protection for internal organs, strength to body regions, or weight-bearing stability. The joint between the manubrium and 6.08C. Give examples of cartilaginous joints. the sternum is an example of a cartilaginous joint. This type of joint also forms the growth regions of immature long bones and the intervertebral discs of the spinal column. The bones of a synovial joint are surrounded by a 6.08D. Illustrate the structure of a synovial joint synovial capsule, which secretes synovial fluid to and explain the roles of the components of a lubricate and nourish the joint while acting as a synovial joint.

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NUR11O1 Integrated Human Anatomy and Physiology Department of Biology Institute of Arts and Sciences Far Eastern University

shock absorber. The ends of the joint bones are covered with smooth, glass-like hyaline cartilage which reduces friction during movement. A synovial joint contains a synovial cavity and dense, irregular connective tissue that forms the articular capsule normally associated with accessory ligaments. 6.08E. Classify synovial joints based on the shape of the bones in the joint and give an example of each type.

6.08F. Demonstrate the difference between the following pairs of movements: flexion and extension; plantar flexion and dorsiflexion; abduction and adduction; supination and pronation; elevation and depression; protraction and retraction; opposition and reposition; inversion and eversion.

The six types of synovial joints allow the body to move in a variety of ways. (a) Pivot joints allow for rotation around an axis, such as between the first and second cervical vertebrae, which allows for side-to-side rotation of the head. (b) The hinge joint of the elbow works like a door hinge. (c) The articulation between the trapezium carpal bone and the first metacarpal bone at the base of the thumb is a saddle joint. (d) Plane joints, such as those between the tarsal bones of the foot, allow for limited gliding movements between bones. (e) The radiocarpal joint of the wrist is a condyloid joint. (f) The hip and shoulder joints are the only ball-and-socket joints of the body. Flexion and extension are movements that take place within the sagittal plane and involve anterior or posterior movements of the body or limbs. For the vertebral column, flexion (anterior flexion) is an anterior (forward) bending of the neck or body, while extension involves a posterior-directed motion, such as straightening from a flexed position or bending backward. Lateral flexion is the bending of the neck or body toward the right or left side. These movements of the vertebral column involve both the symphysis joint formed by each intervertebral disc, as well as the plane type of synovial joint formed between the inferior articular processes of one vertebra and the superior articular processes of the next lower vertebra. Hyperextension is the abnormal or excessive extension of a joint beyond its normal range of motion, thus resulting in injury. Similarly, hyperflexion is excessive flexion at a joint. Hyperextension injuries are common at hinge joints such as the knee or elbow. In cases of

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NUR11O1 Integrated Human Anatomy and Physiology Department of Biology Institute of Arts and Sciences Far Eastern University

“whiplash” in which the head is suddenly moved backward and then forward, a patient may experience both hyperextension and hyperflexion of the cervical region. Abduction and adduction motions occur within the coronal plane and involve medial-lateral motions of the limbs, fingers, toes, or thumb. Abduction moves the limb laterally away from the midline of the body, while adduction is the opposing movement that brings the limb toward the body or across the midline. For example, abduction is raising the arm at the shoulder joint, moving it laterally away from the body, while adduction brings the arm down to the side of the body. Similarly, abduction and adduction at the wrist moves the hand away from or toward the midline of the body. Spreading the fingers or toes apart is also abduction, while bringing the fingers or toes together is adduction. For the thumb, abduction is the anterior movement that brings the thumb to a 90° perpendicular position, pointing straight out from the palm. Adduction moves the thumb back to the anatomical position, next to the index finger. Abduction and adduction movements are seen at condyloid, saddle, and ball-and-socket. Circumduction is the movement of a body region in a circular manner, in which one end of the body region being moved stays relatively stationary while the other end describes a circle. It involves the sequential combination of flexion, adduction, extension, and abduction at a joint. This type of motion is found at biaxial condyloid and saddle joints, and at multiaxial ball-and-sockets joints. Rotation can occur within the vertebral column, at a pivot joint, or at a ball-and-socket joint. Rotation of the neck or body is the twisting movement produced by the summation of the small rotational movements available between adjacent vertebrae. At a pivot joint, one bone rotates in relation to another bone. This is a uniaxial joint, and thus rotation is the only motion allowed at a pivot joint. For example, at the atlantoaxial joint, the first cervical (C1) vertebra (atlas) rotates

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NUR11O1 Integrated Human Anatomy and Physiology Department of Biology Institute of Arts and Sciences Far Eastern University

around the dens, the upward projection from the second cervical (C2) vertebra (axis). This allows the head to rotate from side to side as when shaking the head “no.” The proximal radioulnar joint is a pivot joint formed by the head of the radius and its articulation with the ulna. This joint allows for the radius to rotate along its length during pronation and supination movements of the forearm. Supination and pronation are movements of the forearm. In the anatomical position, the upper limb is held next to the body with the palm facing forward. This is the supinated position of the forearm. In this position, the radius and ulna are parallel to each other. When the palm of the hand faces backward, the forearm is in the pronated position, and the radius and ulna form an Xshape. Dorsiflexion and plantar flexion are movements at the ankle joint, which is a hinge joint. Lifting the front of the foot, so that the top of the foot moves toward the anterior leg is dorsiflexion, while lifting the heel of the foot from the ground or pointing the toes downward is plantar flexion. These are the only movements available at the ankle joint. Inversion and eversion are complex movements that involve the multiple plane joints among the tarsal bones of the posterior foot (intertarsal joints) and thus are not motions that take place at the ankle joint. Inversion is the turning of the foot to angle the bottom of the foot toward the midline, while eversion turns the bottom of the foot away from the midline. Protraction and retraction are anterior-posterior movements of the scapula or mandible. Protraction of the scapula occurs when the shoulder is moved forward, as when pushing against something or throwing a ball. Retraction is the opposite motion, with the scapula being pulled posteriorly and medially, toward the vertebral column. For the mandible, protraction occurs when the lower jaw is pushed forward, to stick out the chin, while retraction pulls the lower jaw backward. Depression and elevation are downward and upward movements of the

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scapula or mandible. The upward movement of the scapula and shoulder is elevation, while a downward movement is depression. These movements are used to shrug your shoulders. Similarly, elevation of the mandible is the upward movement of the lower jaw used to close the mouth or bite on something, and depression is the downward movement that produces opening of the mouth. Excursion is the side to side movement of the mandible. Lateral excursion moves the mandible away from the midline, toward either the right or left side. Medial excursion returns the mandible to its resting position at the midline. Opposition is the thumb movement that brings the tip of the thumb in contact with the tip of a finger. This movement is produced at the first carpometacarpal joint, which is a saddle joint formed between the trapezium carpal bone and the first metacarpal bone. Thumb opposition is produced by a combination of flexion and abduction of the thumb at this joint. Returning the thumb to its anatomical position next to the index finger is called reposition. 6.09A. Describe the effects of aging on bone matrix and joints.

Bone matrix becomes more brittle and decreases in total amount during aging. Joints lose articular cartilage and become less flexible with age. Prevention measures include exercise and calcium and vitamin D supplements.

III. CONCLUSION: Make general statement (Maximum of three sentences on what you have learned on this activity. As a support mechanism for the body, the skeletal system acts. It gives the body its form, facilitates motion, creates blood cells, protects organs and stores minerals. So, being informed about it is quite necessary.

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