SC120-STUDY-GUIDE-2 (2).pdf

FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 2 STUDY GUIDE FOR MODULE NO. ___ PROTECTION, SUP...

FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 2 STUDY GUIDE FOR MODULE NO. ___ PROTECTION, SUPPORT, AND MOVEMENT MODULE OVERVIEW The integument or integumentary system is a fancy name for a very important body system. The skin, the largest organ in the body in terms of surface area, covers about two square meters or 2.2 square feet of the adult human body. It is also the heaviest, with an average weight of 4.5-5.0 kg, and account for approximately seven percent of our body weight. It has an average thickness of 1.5mm, thickest in areas exposed to wear and abrasion (palm and soles), and is thinnest on the eyelids, external gentalia, and eardrum. The skeletal system includes all bones and joints in the body. Each bone is a complex living organ that is made up of many cells, protein fibers, and minerals. The skeleton acts as a scaffold by providing support and protection for the soft tissues that make up the rest of the body. The skeletal system also provides attachment points for muscles to allow movements at the joints. New blood cells are produced by the red bone marrow inside of our bones. Bones act as the body’s warehouse for calcium, iron, and energy in the form of fat. Finally, the skeleton grows throughout childhood and provides a framework for the rest of the body to grow along with it. Muscular system in response to stimuli, organisms move using their contractile proteins, actin and myosin, which are associated by function. In unicellular organisms, these may involve amoeboid, ciliary or flagella locomotion. On the cellular level, many cells process such as the contraction of the cleavage furrow during mitosis, utilize these contractile proteins as well. In complex organisms, such as a higher animals and man, muscles serve as motors which generate mechanical forces and motion. Muscular contraction is the most important mechanism that animals have in response to environmental stimuli. Generally, muscles allow locomotion, manipulation of objects, movement of food through the gut, circulation of blood and many other movements. Muscle cells that are specialized in contraction contain high densities of actin and myosin. Such cells are found attached to the skeleton and are responsible for the former’s movements. Others are located in the walls of the gut, blood vessels, bladder and heart. MODULE LEARNING OBJECTIVES At the end of this Module, you should be able to: 1. describe the layers of the skin, and their respective structure and function. 2. explain how the skin contributes to the regulation of body temperature, storage of blood, protection, sensation, excretion and absorption, and synthesis of vitamin D. 3. Compare the structure, distribution, and functions of the accessory structures of the skin. 4. describe the effects of aging on the integumentary system. 5. Identify key medical terms associated with the integumentary system. 6. describe the structure and major functions of the skeletal system. 7. describe the structural and functional basis for the classification of bones. 8. distinguish between intramembranous and endochondral ossification. 9. explain the importance of the different types of bone formation and the process of bone remodeling. 10. distinguish between axial and appendicular skeleton 11. distinguish between the different types of joints 12. describe the types of movements that can occur at synovial joints. 13. describe the effects of aging on bones. 14. identify key medical terms associated with the skeletal system. 15. compare the three types of muscular tissue with regard to function and special properties. 16. describe the relationship between bones and skeletal. PANGASINAN STATE UNIVERSITY 1  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 17. explain how different muscle groups work together to produce movement. 18. explain the different features used in naming skeletal muscles. 19. identify and describe the major muscles of the body. 20. describe the effects of aging on muscles. 21. identify key medical terms associated with the muscular system. INTEGUMENTARY SYSTEM The following are the key topics for Integumentary system: I. Functions of Integumentary System II. Skin Layers 1. Epidermis 2. Dermis 3. Subcutaneous Layer or Hypodermis 4. More specific Appendages inside the Skin Layer of Human III. Accessory organs of the Skin  Hair  Nails  Glands  Skin Color FUNCTIONS OF INTEGUMENTARY SYSTEM The functions of the integumentary system include the following: 1. Protects the body by acting as barriers to microorganisms, water and excessive sunlight. 2. Protects it against dehydration and water absorption. 3. Regulates body temperature through heat loss from dilated vessels, evaporations from perspiration, and retention from constricted vessels. 4. Serves for cutaneous sensation by its sensory receptors that respond to heat, cold pressure, touch, vibration and pain. 5. Performs metabolic functions as in the synthesis of melanin, keratin and Vitamin D. 6. Contains organs like the sweat glands responsible for the excretion of nitrogenous wastes; and 7. Acts as a blood reservoir. SKIN LAYERS The figure below shows the three-dimensional lateral cut of the human skin. PANGASINAN STATE UNIVERSITY 2  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 The epidermis as shown in figure 1, refers to the surface skin which is the outer protective layer of the skin, it is between 30-50 cells layers thick. Epidermal cells are closely packed and highly mitotic. As cells die in the top layers, new ones produce by the germinative layers are continuously being pushed up. Four types of cells are present in the epidermis: keratinocytes produce keratin – waterproof materials; melanocytes, melanin – pigmentation; Langerhans cells, macrophages – garbage patrol; and Merkell cells, photoreceptors. The epidermis is composed of five layers: 1. Stratum corneum, the outer layer is composed of 20-30 layers of keratinized and cornified dead and flattened cells. 2. Stratum lucidum lies below the stratum corneum. It is composed of lucid and thin layer of cells found only in the palms of the hands and the soles of the feet. 3. Stratum granulosum is just below the stratum lucidum. It is composed of granular cells that contain keratin and deformed nuclei. 4. Stratum spinosum is several layers thick, with cells having dark nuclei and spiny projections. 5. Stratum basale is the deepest layer of the epidermis. It consists of a single layer of actively dividing cells. The keratinocytes, melanocytes and Merkel cells are present in this layer. Dermis. Located deeper than the epidermis, the dermis is composed of elastic and collagenous fibers which function for stretch and strength, respectively. It also contains sweat glands, sebaceous glands, nerve endings, and hair follicles, and is composed of two layers: 1. The upper papillary layer is composed of loose connective tissues with lots of blood vessels. It also contains papillae, fingerlike projections which brings blood vessels near the epidermis and help hold the two layers together. The arrangement of the papillae determines fingerprints. 2. The reticular layer is deeper and thicker than the papillary layer and is composed of dense and stretchable connective tissues. Subcutaneous Layer or Hypodermis The hypodermis is actually not a part of the skin but connects the dermis to the other organs. It stores fat, acts as shock absorber, and anchors the skin to the underlying structures. Fat stored by the adipose tissues of the hypodermics cause "beers belly" in men and thick thighs and buttocks among women. More Specific Appendages inside the Skin layer of Human 1. Arrector pili muscles. Muscles or what we commonly call as ‘goose pimples”. 2. Sensory Nerve Fibers. Its function is to protect the body. It produces cells that will eventually become stratum corneum cells. It contains sensory nerves specifically small diameter sensitive temperature fibers. The sensory nerves in the epidermis serve to sense and transmit heat, pain, and other noxious sensations. 3. Hair Follicle. Bending the hair stimulates the nerve endings allowing a person to feel that the hair has been moved. One of the main functions of hair is to act as a sensitive touch receptor. Sebaceous glands are also associated with each hair follicle that produce an oily secretion to help condition the hair and surrounding skin. 4. Pore. Their purpose is to lubricate the skin. 5. Meissner’s corpuscle. Receptor in the dermis which monitor the duration of a touch and the extent to which it is applied. 6. Pacinian corpuscle. Pressure sensitive receptor. ACCESSORY ORGANS OF THE SKIN 1. Hair Hair is found everywhere in the body except in the palms, soles, lips, penis, and others parts of the female genitalia. There is a dense distribution of hair in the scalp, face, public area, and underarms, while a fair distribution is noticeable in others body areas. Primarily, they function for protection: from injury, sunlight and heat loss (the scalp hair's function); from foreign particles (eyebrows and eyelashes); and from other airborne particles (hairs in the nostrils). A secondary function of the hair is as a sexual attractant. PANGASINAN STATE UNIVERSITY 3  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 The hair is composed of the shaft, root, and bulb. 1. The shaft of the hair determines the curliness of the hair: round shaft (straight hair), oval shaft (wavy hair), and flat shaft (kinky hair). 2. The bulb is the enlarged base of the follicle. The hair bulb forms the base of the hair follicle. In the hair bulb, living cells divide and grow to build the hair shaft. Blood vessels nourish the cells in the hair bulb, and deliver hormones that modify hair growth and the structure at different times of life. 3. The root is encased in an internal or epithelial root sheath (derived from the epidermis), and an external or connective root sheath (derived from the dermis). It is therefore the interacting part to dermis and hypodermis 2. Nails Nails are composed of hard plates of highly keratinized cells and are formed from the stratum corneum of the epidermis. Aside from covering and protecting the dorsal surface of the fingernails and toenails, they also help in grasping and picking small objects. 3. Glands Skin glands are referred to as exocrine glands because their secretions are released to the outside through the ducts. The skin glands include the sebaceous glands, sweat glands and ceruminous glands. a. Sebaceous glands are branched glands attached to the hair follicles. They secrete sebum, a lipid substance directly into the skin surface. This is a natural skin cream because it lubricates and waterproofs the skin. In addition, it performs the following: prevents the hair from becoming brittle, prevents excessive evaporation of water, keeps the skin soft, and contains a bactericidal property that inhibits bacterial growth. b. Sweat (sudoriferous) glands or eccrine sweat glands are coiled tubular glands which excrete perspiration or sweat onto the surface of the skin. They are of two types: eccrine and apocrine. The eccrine glands are widely distributed over the body, especially on the forehead, back palms, and soles. They produce sweat, watery mixture of salts, antibodies and metabolic wastes. The apocrine glands which are much larger, are found in the axillary and pubic regions. They produce a more viscuous and odoriferous secretion which act as sexual attractant. Mammary glands are modified apocrine glands found within the breasts. They secrete milk during lactation. c. Ceruminous glands or ear wax glands are found in the external auditory canal. They secrete cerumen or earwax which acts as insect repellant, and keeps the eardrum from dying. 4. Skin Color PANGASINAN STATE UNIVERSITY 4  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 Three main pigments of determine the color of our skin. 1. Melanin can be found in shades of yellow, brown, and black. The melanocytes make the melanin, which is picked up by the keratinocytes via phagocytosis. Melanin is important because it protects DNA in the nucleus from UV radiation. Figure 2 shows the phenomenon how the skin color of human differs and this is due to the secreted melanosomes that can be of shade of dark to light. 2. Carotene is a yellow to orange pigment that accumulates in the stratum corneum as can be seen in the figure 3 which is Figure 1. Melanocytes and Kerarinocytes magnified portion of the stratum corneum. Further, this pigment can also be found in the adipose tissue found in the hypodermis. Stores fats as shock absorber (see figure 4). Figure 3. Carotene near the Stratum Corneum 3. Hemoglobin is the oxygen- carrying protein found Figure 4. Carotene in the Hypodermis in our red blood cells. A pink color of a fair skin is due to oxygenated haemoglobin (see figure 5b) of the blood in underlying blood vessels. If the blood is not adequately oxygenated, the hemoglobin will be blue in color (see figure 5a, and so the skin be a normal situation, and might indicate anemia, or other impairment in oxygen delivery (due to heart attack, respiratory failure, etc.) a b PANGASINAN STATE UNIVERSITY 5  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 Life-Span Changes We are more aware of aging-related changes in skin than in other organ systems, simply because we can easily see them. Aging skin affects appearance, temperature regulation, and vitamin D activation. The epidermis maintains its thickness as the decades pass, but as the cell cycle slows, cells tend to grow larger and more irregular in shape. Skin may appear scaly because, at the microscopic level, more sulfur— sulfur bonds form within keratin molecules. Patches of pigment commonly called "age spots" or "liver spots" appear and grow. These are sites of oxidation fats in the secretory cells of apocrinc and eccrino glands and reflect formation of oxygen free radicals. The dermis becomes reduced as synthesis of the connective tissue proteins collagen and elastin slows. The combination of a shrinking dermis and loss of some fat from the subcutaneous layer results in wrinkling and sagging of the skin. Fewer lymphocytes delay wound healing. Some of the changes in the skin's appearance result from specific deficits. Less oil from sebaceous glands means that the skin becomes considerably drier. The skin's accessory structures also show signs of aging. Slowed melanin production causes hair to become gray or white as the follicle becomes increasingly transparent. Hair growth slows, the hairs thin, and the number of follicles decreases. Males may develop pattern baldness, which is hereditary but not often expressed in females. A diminished blood supply to the nail beds impairs their growth, dulling and hardening them. Sensitivity to pain and pressure diminishes with age as the number of receptors falls. A ninety-year-old's skin has only one-third the number of such receptors as the skin of a young adult. The ability to control temperature falters as the number of sweat glands in the skin falls, as the capillary beds that surround sweat glands and hair follicles shrink, and as the ability to shiver declines. In addition, the number of blood vessels in the deeper layer decreases, as does the ability to shunt blood towards the body's interior to conserve heat. As a result, an older person is less able to tolerate the cold and cannot regulate heat. An older person might set the thermostat ten to fifteen degrees higher than a younger person in the winter. Fewer blood vessels in and underlying the skin account for the pale complex. ions of some older individuals. Changes in the distribution of blood vessels also contribute to development of pressure sores in a bedridden person whose skin does not receive adequate stimulation. Aging of the skin is also related to skeletal health. The skin is the site of activation of vitamin D, which requires exposure to the sun. Vitamin D is necessary for the absorption of calcium by bone tissue. Many older people do not get outdoors much, and the wavelengths of light that are important for vitamin D activation do not readily penetrate glass windows. In addition, older skin has a diminished ability to activate the vitamin. Therefore, homebound seniors often take vitamin D supplements to help maintain bone structure. LEARNING ACTIVITY 1 1.Draw a Diagram of the skin including its accessory organs and label the parts. 2. Write your name, year, course and section and the date at the upper part of your activity sheets. 3.. Prepare your answers and sending it directly in the Learning Management System. LEARNING CONTENTS (title of the subsection). PANGASINAN STATE UNIVERSITY 6  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 LEARNING ACTIVITY 2 1. explain how the skin contributes to the regulation of body temperature, storage of blood, protection, sensation, excretion and absorption, and synthesis of vitamin D. 2. Write your name, year, course and section and the date at the upper part of your activity sheets. 3. Prepare your answers and sending it directly in the Learning Management System. SUMMARY The integumentary system consist of the skin, hair, nails, and variety of glands. The skin protects, helps and regulate body temperature produces Vitamin D and detects stimuli. Skin Layers  Epidermis  Dermis  Subcutaneous Layer or Hypodermis  More specific Appendages inside the Skin Layer of Human Accessory organs of the Skin  Hair  Nails  Glands  Skin Color FUNCTIONS OF INTEGUMENTARY SYSTEM The functions of the integumentary system include the following:  Protects the body by acting as barriers to microorganisms, water and excessive sunlight.  Protects it against dehydration and water absorption.  Regulates body temperature through heat loss from dilated vessels, evaporations from perspiration, and retention from constricted vessels;  Serves for cutaneous sensation by its sensory receptors that respond to heat, cold pressure, touch, vibration and pain.  Performs metabolic functions as in the synthesis of melanin, keratin and Vitamin D.  Contains organs like the sweat glands responsible for the excretion of nitrogenous wastes; and  Acts as a blood reservoir. EFFECTS OF AGING ON THE INTEGUMENTARY SYSTEM  As the body ages, blood flow to the skin is reduced, the skin becomes thinner and elasticity is lost.  Sweat and sebaceous glands are less active, and the number of melanocytes decreases. REFERENCES  Human Anatomy and Physiology work Book and Laboratory Manual by Ho,Gan,Verbo,Guerrero pp 91  Seeley,Rod R., et. al. 2003. Anatomy and Physiology. 3rd Ed. Mosby-yearbook Inc. USA. Pp 160-161  Human Anatomy and Physiology by David Shier,Jackie Butler, Riccki Lewis 10th Ed. Pp 175-176  Penecilla Gerald, L. Formacion, N. Fandialan, N. Valmote, M. Sandoval, and N. PANGASINAN STATE UNIVERSITY 7  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2  Esmeralda. 2003. Basic Concepts in Biology. Philppines: Trintas Publishing, Inc.. pp 119-124  Camara, Jun, F. N. Caranay, and P. Agsalud. 2012. Introduction to Biology. Malabon  City: Jimczyville Publications. pp 71  https://www.dummies.com/education/science/anatomy/standard-anatomical-position/  http://encyclopedia.lubopitko-bg.com/Anatomical_Terms.html  https://en.wikipedia.org/wiki/Quadrants_and_regions_of_abdomen  http://www.scientistcindy.com/body-cavities-and-membranes.html  https://microbenotes.com/homeostasis/  https://training.seer.cancer.gov/anatomy/body/functions.html#:~:text=The%20basic%20processes%2 0of%20life,of%20these%20processes%20are%20interrelated.  https://biologydictionary.net/organ-system/  http://fwf.ag.utk.edu/mgray/wfs493/Lectures/AmphibianPhysiology.pdf  http://www.scielo.br/pdf/zool/v34/1984-4689-zool-34-e20176.pdf  https://www.bscsd.org/site/handlers/filedownload.ashx?moduleinstanceid=809&dataid  4155&FileName=frog%20body%20systems.pdf  https://en.wikibooks.org/wiki/The_Organ_Systems/integumentary  http://www.thefrog.org/biology/skin/skin.htm  https://www.transtutors.com/biology-homework-help/zoology/functions-of-skin-of-frog/  https://www.wemed.com/skin-problems-and -treatments/picture-of-the-hair  https://en.wikibooks.org/wiki/The_Organ_Systems/integumentary  http://ehabhanhan.blogspot.com/2013/06/integumentary-system.html  http://pediaa.com/what-is-the-difference-between-frog-and-human-integumentary  system/  https://www.google.com/search?q=skin+of+frog+parts&source=lnms&tbm=isch&sa=  &ved=0ahUKEwjw4OTf6vHgAhUadt4KHfj9C1oQ_AUIDigB&biw=1366&bih=625  mgrc=HQEax36SD2d3MM PANGASINAN STATE UNIVERSITY 8  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 SKELETAL SYSTEM OVERVIEW OF THE SKELETON Bones may be classified as follows: According to size and shape  Long bones are typically longer. Ex. Are bones of the limbs (femur).  Short bones are generally cube shaped. Ex. Are wrist (carpals) and ankle bones (tarsal).  Flat bones are thin, flattened, and usually curved. Ex. Are ribs, breast, and cranial bones.  Irregular bones, like vertebrae and hip bones (pelvis), vary in shape. Origins or type of ossification (bone-formation)  Cartilaginous/Endochondral Ossification – bones are developed from cartilage models. Ex. Short and long bones.  Membranous – bones are form to connective tissue membranes. Ex. Frontal and parietal bones of the skull, and mandible. Structure  Spongy or Cancellous bone is composed of branching beams of hard bones called trabeculae and open spaces. It is found in the inner portion of a bone organ.  Compact bone is formed by solid matrix of cylindrical units called osteons or Haversian systems that are tightly packed together. It is mostly found at the diaphysis of long bones. Location  Axial skeleton consists of 80 bones that are located along the central axis of the body. This includes the skull, hyoid, spinal column, ribs and sternum.  Appendicular skeleton consist of 126 bones that are located in the peripheral part of the body. This includes the upper and lower extremities. PANGASINAN STATE UNIVERSITY 9  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 HUMAN SKELETAL SYSTEM The figure below shows the human skeletal system and its different parts. Figure 1. Human Skeletal System PANGASINAN STATE UNIVERSITY 10  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 FUNCTION OF THE SKELETAL SYSTEM Skeletal system provides several important functions in the body. Some major functions include: 1. Movement: Skeletal system provides points of attachment for muscles. Your legs and arms move when the muscles pull on the bones. 2. Support: The backbone is the main support center for the upper body. It holds your head up and protects your spinal cord. 3. Protection: The bones of your skull protect your brain. Your ribs protect your lungs and hearth from injury. 4. Makes blood: Red and white blood cells are formed by tissue called marrow, which is in the center of the bone. 5. Storage: Bones store minerals, such as calcium and phosphorus, for use by the body. KINDS OF SKELETAL SYSTEM Animals have three different types of support systems namely: hydrostatic skeleton, exoskeleton and endoskeleton. A skeletal system is necessary to support the body, protect internal organs, and allow for the movement of an organism. 1. Hydrostatic Skeleton A hydrostatic skeleton is one that contains no rigid, hard structures or bones for support, but rather relies on a fluid-filled cavity surrounded by muscles. It is the skeleton adopted by worms, starfish and other invertebrates, and carries with it a number of advantages and disadvantages over a more solid frame. 2. Exoskeleton An exoskeleton is an external skeleton that consists of a hard encasement on the surface of an organism. For example, the shells of crabs and insects are exoskeletons. This skeleton type provides defense against predators, supports the body, and allows for movement through the contraction of attached muscles. 3. Endoskeleton An endoskeleton is a skeleton that consists of hard, mineralized structures located within the soft tissue of organisms. An example of a primitive endoskeleton structure is the spicules of sponges. The bones of vertebrates are composed of tissues, whereas sponges have no true tissues. Endoskeletons provide support for the body, protect internal organs, and allow for movement through contraction of muscles attached to the skeleton. DIVISION/LOCATION OF SKELETAL SYSTEM The skeleton is subdivided into two divisions--the axial and appendicular. 1. Axial Skeleton - composed of 80 bones; the axial bone forms the vertical axis of the body and renders support to the organs of the head, neck and trunk. The figure below shows the axial skeleton includes all the bones along the body’s long axis. PANGASINAN STATE UNIVERSITY 11  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 A. SKULL 1. Cranial Bones - protect the brain and sense organs. a. Frontal Bone b. Parietal Bone c. Temporal Bone d. Occipital Bone e. Sphenoid Bone f. Ethmoid Bone 2. Face a. Zygomatic Bone (cheek bone) b. Maxilla Bone c. Nasal Bone d. Lacrimal Bone e. Vomer Bone f. Palatine Bone g. Inferior conchae h. Mandible Bone 3. Auditory Ossicles - composed of the three pairs of small bones, namely: the malleus (hammer). Incus (anvil) and stapes (stirrup). These are all located in the middle ear; their movement transmits the sound waves from the eardrum to the oval window of the inner ear. B. STERNUM - is a flat, elongated, dagger-shaped bone found in the middle of the chest. It protects the heart, lungs and major blood vessels from damage as it completes the circle of the rib cage. It composed of three segments. 1. Manubrium or the handle 2. Gladiolus or blade 3. Xiphoid process or the tip The figure below shows the sternum or the breastbone: C. RIBS - pairs of 12 thin, flat, curved bones form a around the organs the upper body. PANGASINAN STATE UNIVERSITY 12  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 1. Vertebrosternal or true rib 2. Vertebrochondrial or false ribs 3. Vertebral ribs The figure below shows the human ribs. D. HYOID - is not connected directly to any other bone. It is shaped like a horseshoe and located between the mandible and the larynx. This bone supports the tongue and provides attachments for some of its muscles. The figure below shows the hyoid bone. E. Column Vertebral - commonly known as the backbone, spine, or spinal column is composed of 26 irregularly-shaped bones divided into the following: 1. Thoracic vertebrate 2. Lumbar vertebrate 3. Sacrum 4. Coccyx or tailbone 5. Cervical vertebrate Extremities The figure below shows the column vertebral. PANGASINAN STATE UNIVERSITY 13  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 2. Appendicular skeleton- this is composed of 126 bones of the upper and lower extremities, and the pectoral and pelvic girdles and anchors the appendages to the axial skeleton. The figure below shows the appendicular skeleton includes all the bones that form the upper and lower limbs, and the shoulder and pelvic girdles. A. Upper extremities - consist of the arms, the forearms, and the hands. 1. Brachium or arm 2. Antibrachium or forearm 3. Hand The figure below shows the parts of the upper extremities of the body. B. Lower extremities - are composed of the bones of the thigh, leg, foot, and the patella (commonly known as the kneecap) 1. Femur or thigh 2. Leg 3. Pes or foot 4. Patella or kneecap The figure below shows the parts of the lower extremities of the body. PANGASINAN STATE UNIVERSITY 14  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 C. Pectoral girdle or the shoulder - girdle is composed of four bones, two clavicles, and two scapulae. 1. Clavicle 2. Scapula The figure below shows the pectoral girdle consists of two bones, the scapula and clavicle D. Pelvic girdle also called the hip girdle - is composed of two coxal (hip) bones. The coxal bones are also called the ossa coxae or innominate bones. The figure below shows the pelvic girdle which serve as the attachment point for each lower limb. CLASSIFICATION OF BONES The 206 bones that compose the adult skeleton are divided into four categories based on their shapes. 1. Long bones - They are long and slender bones found generally in the limbs. The figure below shows the shape of a long bone. 2. Short Bones - They are short bones which are smaller in size and are found in the carpals and tarsal. The figure below shows the shape of a short bones. PANGASINAN STATE UNIVERSITY 15  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 3. Flat Bones - they are thin and flat in nature and not all of them are completely flat. They provide surface area for muscle attachment. Ex: scapula, sternum. The figure below shows the shape of a flat bones. 4. Irregular Bones - These bones do not have specific shapes and therefore cannot be put into any other group. STRUCTURE OF BONES Bones are composed of two types of tissue: The figure below is the Compact bone and Spongy bone. 1. Compact bone tissue forms the outer shell of bones. It consists of a very hard (virtually solid) mass of bony tissue arranged in concentric layers (Haversian systems). 2. Cancellous (also known as 'spongy') bone tissue is located beneath the compact bone and consists of a meshwork of bony bars (trabeculae) with many interconnecting spaces containing bone marrow. Classification of Joints on the Basis of Structure and Function The point at which two or more bones meet is called a joint or articulation. Joints are responsible for movement (e.g., the movement of limbs) and stability (e.g.,the stability found in the bones of the skull). There are two ways to classify joints: on the basis of their structure or on the basis of their function. 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 functional classification divides joints into three categories: synarthroses, amphiarthroses, and diarthroses. PANGASINAN STATE UNIVERSITY 16  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 Fibrous Joints The bones of fibrous joints are held together by fibrous connective tissue. There is no cavity, or space, present between the bones, so most fibrous joints do not move at all. There are three types of fibrous joints: sutures, syndesmoses, and gomphoses. Sutures are found only in the skull and possess short fibers of connective tissue that hold the skull bones tightly in place. Figure 38.3A.138.3A.1: Sutures: Sutures are fibrous joints found only in the skull. Syndesmoses are joints in which the bones are connected by a band of connective tissue, allowing for more movement than in a suture. An example of a syndesmosis is the joint of the tibia and fibula in the ankle. The amount of movement in these types of joints is determined by the length of the connective tissue fibers. Gomphoses occur between teeth and their sockets; the term refers to the way the tooth fits into the socket like a peg. The tooth is connected to the socket by a connective tissue called the periodontal ligament. Fibrous joints classified as synarthroses, or immovable, include: sutures, gomphoses, and synchondroses PANGASINAN STATE UNIVERSITY 17  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 Figure 38.3A.138.3A.1: Gomphoses: Gomphoses are fibrous joints between the teeth and their sockets. Cartilaginous Joints Cartilaginous joints are those in which the bones are connected by cartilage. There are two types of cartilaginous joints: synchondroses and symphyses. In a synchondrosis, the bones are joined by hyaline cartilage. Synchondroses are found in the epiphyseal plates of growing bones in children. In symphyses, hyaline cartilage covers the end of the bone, but the connection between bones occurs through fibrocartilage. Symphyses are found at the joints between vertebrae and between the pubic bones. Amphiarthroses allow only slight movement; therefore, either type of cartilaginous joint is an amphiarthrosis. Synovial Joints Synovial joints are the only joints that have a space between the adjoining bones. This space, referred to as the synovial (or joint) cavity, is filled with synovial fluid. Synovial fluid lubricates the joint, reducing friction between the bones and allowing for greater movement. The ends of the bones are covered with articular cartilage, a hyaline cartilage. The entire joint is surrounded by an articular capsule composed of connective tissue. This allows movement of the joint as well as resistance to dislocation. Articular capsules may also possess ligaments that hold the bones together. Synovial joints are capable of the greatest movement of the three structural joint types; however, the more mobile a joint, the weaker the joint. Knees, elbows, and shoulders are examples of synovial joints. Since they allow for free movement, synovial joints are classified as diarthroses. PANGASINAN STATE UNIVERSITY 18  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 Figure 38.3A.138.3A.1: Synovial Joints: Synovial joints are the only joints that have a space or “synovial cavity” in the joint. STRUCTURAL CLASSIFICATION OF JOINTS The structural classification of joints is based on whether the articulating surfaces of the adjacent bones are directly connected by fibrous connective tissue or cartilage, or whether the articulating surfaces contact each other within a fluid-filled joint cavity. These differences serve to divide the joints of the body into three structural classifications. A fibrous joint is where the adjacent bones are united by fibrous connective tissue. At a cartilaginous joint, the bones are joined by hyaline cartilage or fibrocartilage. At a synovial joint, the articulating surfaces of the bones are not directly connected, but instead come into contact with each other within a joint cavity that is filled with a lubricating fluid. Synovial joints allow for free movement between the bones and are the most common joints of the body. FUNCTIONAL CLASSIFICATION OF JOINTS The functional classification of joints is determined by the amount of mobility found between the adjacent bones. Joints are thus functionally classified as a synarthrosis or immobile joint, an amphiarthrosis or slightly moveable joint, or as a diarthrosis, which is a freely moveable joint (arthroun = “to fasten by a joint”). Depending on their location, fibrous joints may be functionally classified as a synarthrosis (immobile joint) or an amphiarthrosis (slightly mobile joint). Cartilaginous joints are also functionally classified as either a synarthrosis or an amphiarthrosis joint. All synovial joints are functionally classified as a diarthrosis joint. PANGASINAN STATE UNIVERSITY 19  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 SYNARTHROSIS An immobile or nearly immobile joint is called a synarthrosis. The immobile nature of these joints provide for a strong union between the articulating bones. This is important at locations where the bones provide protection for internal organs. Examples include sutures, the fibrous joints between the bones of the skull that surround and protect the brain (Figure 1), and the manubriosternal joint, the cartilaginous joint that unites the manubrium and body of the sternum for protection of the heart. Figure 1. Suture Joints of SkulAMPHIARTHROSIS PANGASINAN STATE UNIVERSITY 20  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 AMPHIARTHROSIS An amphiarthrosis is a joint that has limited mobility. An example of this type of joint is the cartilaginous joint that unites the bodies of adjacent vertebrae. Filling the gap between the vertebrae is a thick pad of fibrocartilage called an intervertebral disc (Figure 2). Each intervertebral disc strongly unites the vertebrae but still allows for a limited amount of movement between them. However, the small movements available between adjacent vertebrae can sum together along the length of the vertebral column to provide for large ranges of body movements. Another example of an amphiarthrosis is the pubic symphysis of the pelvis. This is a cartilaginous joint in which the pubic regions of the right and left hip bones are strongly anchored to each other by fibrocartilage. This joint normally has very little mobility. The strength of the pubic symphysis is important in conferring weight-bearing stability to the pelvis. Figure 2. Intervertebral Disc. An intervertebral disc unites the bodies of adjacent vertebrae within the vertebral column. Each disc allows for limited movement between the vertebrae and thus functionally forms an amphiarthrosis type of joint. Intervertebral discs are made of fibrocartilage and thereby structurally form a symphysis type of cartilaginous joint. DIARTHROSIS A freely mobile joint is classified as a diarthrosis. These types of joints include all synovial joints of the body, which provide the majority of body movements. Most diarthrotic joints are found in the appendicular skeleton and thus give the limbs a wide range of motion. These joints are divided into three categories, based on the number of axes of motion provided by each. An axis in anatomy is described as the movements in reference to the three anatomical planes: transverse, frontal, and sagittal. Thus, diarthroses are classified as uniaxial (for movement in one plane), biaxial (for movement in two planes), or multiaxial joints (for movement in all three anatomical planes). PANGASINAN STATE UNIVERSITY 21  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 A uniaxial joint only allows for a motion in a single plane (around a single axis). The elbow joint, which only allows for bending or straightening, is an example of a uniaxial joint. A biaxial joint allows for motions within two planes. An example of a biaxial joint is a metacarpophalangeal joint (knuckle joint) of the hand. The joint allows for movement along one axis to produce bending or straightening of the finger, and movement along a second axis, which allows for spreading of the fingers away from each other and bringing them together. A joint that allows for the several directions of movement is called a multiaxial joint (polyaxial or triaxial joint). This type of diarthrotic joint allows for movement along three axes (Figure 3). The shoulder and hip joints are multiaxial joints. They allow the upper or lower limb to move in an anterior-posterior direction and a medial- lateral direction. In addition, the limb can also be rotated around its long axis. This third movement results in rotation of the limb so that its anterior surface is moved either toward or away from the midline of the body. Figure 3. Multiaxial Joint. A multiaxial joint, such as the hip joint, allows for three types of movement: anterior-posterior, medial-lateral, and rotational. The Aging Bone Bones undergo a lifelong process of remodeling – mature bone tissue is removed and new bone tissue is formed. Bone remodeling is a highly regulated process that maintains a balance between bone resorption and formation, thus maintaining skeletal integrity. This balance changes with increasing age, resulting in loss of bone tissue. The ageing bone has reduced mineral content, and is prone to osteoporosis – a condition in which bones are less dense, more fragile, and prone to fractures. As people age the rate of bone resorption by osteoclast cells (multinucleated cells which contain mitochondria and lysosomes that is responsible for bone resorption) exceeds the rate of bone formation so bone weaken. And this all happens due to:  Inactive life style  Hormonal changes  Loss of calcium and other minerals in bone Effects of Changes in Aging Bone  Osteoporosis is a common problem among older people, especially post-menopausal women, and is a major cause of hip fractures in the elderly. PANGASINAN STATE UNIVERSITY 22  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2  Reduced bone density of the vertebrae, combined with the loss of fluid in intervertebral discs, result in a curved and shortened trunk.  This reduced bone density, and resulting poor posture, leads to pain, reduced mobility, and other musculoskeletal problems.  The risk of injury increases because gait changes, instability, and loss of balance may lead to falls. Ageing Joints Joint motion becomes more restricted and flexibility decreases with age because of changes in tendons and ligaments. As the cushioning cartilage begins to break down from a lifetime of use, joints become inflamed and arthritic. PANGASINAN STATE UNIVERSITY 23  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 LEARNING ACTIVITY 2 1. Draw and label a skeleton in a posterior and anterior view. 2. Draw and label axial and appendicular skeleton. 3. Enumerate the classification of joints according to structure and movements.  Prepare your answers sending it directly in the Learning Management System.  Write your name, year, course and section and the date at the upper part of your answer activity sheet. REFERENCES Penecilla Gerald, L. Formacion, N. Fandialan, N. Valmote, M. Sandoval, and N. Esmeralda. 2003. Basic Concepts in Biology. Philppines: Trintas Publishing, Inc.. pp 119-124 https://m.ivyroses.com/HumanBody/Skeletal/SkeletalSystem.php https://www.pharmatips.in/Articles/Human-Anatomy/Introduction-To-Skeletal-System- Anatomy.aspx https://opentextbc.ca/biology/chapter/19-1-types-of-skeletal-systems/ https://biologydictionary.net/skeletal-sydstem/ https://www.acls.net/human-sssskkeletal-system https://nursingexamppaper.com/2017/12/the-skeletal-system-part-and-functions.html https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book%3A_General_Biology_(Bo undless)/38%3A_The_Musculoskeletal_System/38.3%3A_Joints_and_Skeletal_Movement/38.3A%3A_Class ification_of_Joints_on_the_Basis_of_Structure_and_Function#:~:text=The%20structural%20classification %20divides%20joints,synarthroses%2C%20amphiarthroses%2C%20and%20diarthroses. https://opentextbc.ca/anatomyandphysiology/chapter/9-1-classification-of-joints/ SUMMARY Human skeleton The healthy skeletal system is made up of bones, ligaments, and cartilage. The Skeletal System Consists of More Than Bones When you look at the human skeleton the 206 bones and 32 teeth stand out. But look closer and you’ll see even more structures. The human skeleton also includes ligaments and cartilage. Ligaments are bands of dense and fibrous connective tissue that are key to the function of joints. Cartilage is more flexible than bone but stiffer than muscle. Cartilage helps give structure to the larynx and nose. It is also found between the vertebrae and at the ends of bones like the femur. The Adult Human Skeleton Is Made Up of 206 Bones SKULL - 22 SHOULDER GIRDLE/UPPER EXTREMETIES- 64 THORACIC- 25 VERTEBRAL COLUMN- 33 PELVIC GIRDLE/LOWER EXTREMETIES-62 PANGASINAN STATE UNIVERSITY 24  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 These bones provide structure and protection and facilitate motion. Bones articulate to form structures. The skull protects the brain and gives shape to the face. The thoracic cage surrounds the heart and lungs. The vertebral column, commonly called the spine, is formed by over 30 small bones. Then there are the limbs (upper and lower) and the girdles that attach the four limbs to the vertebral column. The Skeleton Protects Vital Organs The brain is surrounded by bones that form part of the skull. The heart and lungs are located within the thoracic cavity, and the vertebral column provides structure and protection for the spinal cord.. Bones Are Grouped into the Axial Skeleton and the Appendicular Skeleton Bones of the appendicular skeleton facilitate movement, while bones of the axial skeleton protect internal organs. All skeletal structures belong to either the appendicular skeleton (girdles and limbs) or to the axial skeleton (skull, vertebral column, and thoracic cage). STRUCTURAL CLASSIFICATION OF JOINTS The structural classification of joints is based on whether the articulating surfaces of the adjacent bones are directly connected by fibrous connective tissue or cartilage, or whether the articulating surfaces contact each other within a fluid-filled joint cavity. These differences serve to divide the joints of the body into three structural classifications. A fibrous joint is where the adjacent bones are united by fibrous connective tissue. At a cartilaginous joint, the bones are joined by hyaline cartilage or fibrocartilage. At a synovial joint, the articulating surfaces of the bones are not directly connected, but instead come into contact with each other within a joint cavity that is filled with a lubricating fluid. Synovial joints allow for free movement between the bones and are the most common joints of the body. FUNCTIONAL CLASSIFICATION OF JOINTS The functional classification of joints is determined by the amount of mobility found between the adjacent bones. Joints are thus functionally classified as a synarthrosis or immobile joint, an amphiarthrosis or slightly moveable joint, or as a diarthrosis, which is a freely moveable joint (arthroun = “to fasten by a joint”). Depending on their location, fibrous joints may be functionally classified as a synarthrosis (immobile joint) or an amphiarthrosis (slightly mobile joint). Cartilaginous joints are also functionally classified as either a synarthrosis or an amphiarthrosis joint. All synovial joints are functionally classified as a diarthrosis joint. PANGASINAN STATE UNIVERSITY 25  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 MUSCULAR SYSTEM The following are the topics to be discussed: I. TYPES OF MUSCLE 1. Skeletal Muscles 2. Smooth Muscles 3. Cardiac Muscles II. TYPES OF MUSCLE TISSUES III. MUSCLE ACTION 1. Antagonistic action of the skeletal muscles, biceps, and triceps IV. MUSCLE STRUCTURE AND FUNCTION 1. The Structure of the skeletal muscle from tissues down to molecules V. ROLE OF ATP IN MUSCLE CONTRACTION VI. SUMMARY OF MUSCULAR CONTRACTION TYPES OF MUSCLES There are three main types of muscles- smooth, skeletal and cardiac – each performing special functions in the body. 1. Skeletal muscles move the bones performing voluntary actions, like walking and running, as well as breathing. Skeletal muscles are large and striated owing the regular pattern of arrangement of actin and myosin filaments. They process many nuclei. A condition kwon as syncytium, because they develop through the fusion of many individual cells. 2. Smooth muscles are the simplest muscle cells. They are under the control of the autonomic nervous system, contracting continuously in a steady and a slow manner. Smooth muscles are elongated and spindle-shape, processing a centrally- located nucleus per cell. The actin and myosin fibers are not regularly arranged, so these are not obvious when the cells are viewed under a light microscope. The cells are arranged in sheets, and are found in the walls of the digestive tract and blood vessels. 3. Cardiac muscles are found in the heart where the cells form long rows of fibers. Unlike other muscles tissues, cardiac muscles contract independently of nerve supply since reflex activity and electrical stimuli are contained within the cardiac muscles themselves. Thus, they move involuntarily like the smooth muscles. Similar to the skeletal muscles, they process striations, but these are with branches which connect the fibers together. They may have one or two nuclei. Each fibers is divided into partitions or intercalated discs which serve as boundaries between cells. TABLE 1: TYPES OF MUSCLES TISSUES Criteria Skeletal Smooth Cardiac Location Attached to skeleton Walls of guts, blood Walls of hearts vessels Shape of fibers Elongated cylindrical, Elongated, pointed ends, Elongated, Cylindrical blund ends spindle-shaped fibers with branches and fused Type of control Voluntary Involuntary Involuntary Number of nuclei per Many/peripheral One/central One to two/ central fiber/ position Striation Present Absent Present Speed of contraction Most rapid Slowest Intermediate Ability to remain Least Greatest Intermediate contracted Figure 1 show (a) Striated muscles possess dark and light striationsand many nuclei. (b) Smooth muscles are spindle-shaped and have one nucleus per cell, but without distinct striations. (c) Cardiac muscles have distinct striations, one or two cell nuclei and are branched. There are intercalary dics which separate the cells from each other. PANGASINAN STATE UNIVERSITY 26  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 a b c Figure 2. Types of Muscle Tissue MUSCLE ACTION Skeketal muscles produce movement by pulling on tendons, connective tissus that anchor muscles to bones, which in turn pull on bones. Most mucsles pas arcoss a joint and are attached to the bones that form the joint. Muscles move body parts in an opposite or antagonistic manner. The movement produced by one can be reversed by the other. For example, the biceps of your upper arm allows you to pull your arm, while the tricepss permits you to extend it once again. The muscle constracting to produce a particular action is called an agonist, the other doing the opposite relaxing action is referred to as the antagonist. Muscles usually work together as a group and as such several agonist and several antagonist coordinate with one another. They can also switch roles as they move. The figure below shows how antagonistic action of the skeletal muscles happen. Figure 3. Antagonistic action of the skeletal muscles, biceps, and triceps MUSCLE STRUCTURE AND FUNCTION Muscle contraction causes a skeletal part to move or may cause a change in the shape and size of a soft tissue. Contraction results from the gliding past each other of the protein filament mentioned earlier, notable: the thick myosin and thin actin connected by molecules bridges, the cross bridges. The filaments form larger units, the myofibrils, which in turn form the muscle fiber. A skeletal muscle is composed of muscle fibers. The details of the molecules structure of a myofibril are shown in Figure 3 and 4. There is a partial overlap of actin and myosin filament the A-band which appears as dark band. Where there are only actin filaments and no overlap occurs the myofibril appears light, forming the I-band, hence the dark and light striations in skeletal muscle. One whole A-band plus two halves of the I-band on both sides constitute a sarcomere, the functional unit of the skeletal muscle. Note that myosin filaments consist of long polypeptide tails and globular heads Actin PANGASINAN STATE UNIVERSITY 27  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 consists of two chains of monomers twisted each other. Two polypeptide chains of tropomyosin twist around the actin chains (see Figure 3). Figure 4: The Structure of the skeletal muscle from tissues down to molecules The gliding filament theory of muscle contraction was proposed by Huxley and Huxley (cited by Purves, et al. 1995) to explain how muscles contract (Fig. 3.5b). The acting filaments move toward the middle of the myofibril. The myosin heads attach to binding sites in the action filament. Calcium and ATP are required in the process. As this occurs, the muscle shortens, and when many sarcomeres contract simultaneously, they cause the muscle as a whole to contract. Figure 4 shows the structure of a myofibril showing the orderly arrangement of the filaments (a); and the sliding filament theory of muscular contraction (b). The amount of overlap of the myofibril increase during contraction, thus shortening the sarcomere (b). Refer to the text for the identification of the bands in (a). a b Figure 5. Structure of a myofibril PANGASINAN STATE UNIVERSITY 28  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 ROLES OF ATP IN MUSCLE CONTRACTION Many muscles of the body perform strenuous activities which require a continuous supply of energy. ATP is the immediate effect source of energy in muscle contraction. However in strenuous activities sufficient energy can be stored in ATP for only a few second. Thus, the muscle must have other energy sources, such as creatine phosphate (CP), which can be stockpiled. Energy from creatine phosphate can be transferred to ATP. Similarly, during strenuous exercise the supply of CP does not last long, and muscle cells must replenish thier supply of these energy-rich compounds. Recall that glycogen, a large polysaccharide, is stored in muscle fibers and the liver. Stored glycogen is degraded, yielding glucose which is broken down cellular respiration. When oxygen is sufficient, enough energy is captured from glucose to produce the required quantities of ATP. During continuous exercise, oxygen supply may not be sufficient to meet the needs of rapidly metabolizing cells. Under this condition, muscle cells can undergo anaerobic (without oxygen) metabolism to produce ATP rapidly, but in small quantities and for short periods of time. Muscle fatigue results with the depletion of ATP. The accumulation of lastic acid during anaerobic respiration also contribution to muscle fatigue. Finally, the depletion of glycogen and the build -up of lastic acid create an oxygen debt which should be paid back by rapid breathing and aerobic metabolism. Observe how after running fast you need to stop for breath and breathe in rapid succession, in order to replenish your oxygen supply. The action is your body's way of repaying your oxygen debt. SUMMARY OF MUSCULAR CONTRACTION 1. Nerve impulse passes down a motor neuron release Acetylcholine initiate action potential 2. Sarcoplasmic reticulum releases (exposes binding sites in actin) 3. Actin + Myosin Crossbridge Muscle contracts (+Ca++) (formed between actin & myosin) (filaments glide past each other) 4. ATP binds to myosin head, thus releasing actin (cross bridge destroyed). 5. Ca++ is returned to sarcoplasm muscle release AGING AND THE MUSCULAR SYSTEM As we age our muscles undergo progressive changes, primarily involving loss of muscle mass and strength. The age-related loss of muscle function is known as Sarcopenia], derived from the Greek words for flesh (sarcos) and loss (penia) and its definition includes loss of muscle strength and power, as well as reduced function. It occurs with increasing age, and is a major component in the development of frailty. The loss of muscle mass during the aging process is important clinically as it reduces strength and exercise capacity, both which are needed to perform activities of daily living. Sarcopenia is not a disease but rather refers specifically to the universal, involuntary decline in lean body mass that occurs with age, primarily due to the loss of skeletal muscle. Systematic review and meta-analyses among Japanese community-dwelling older adults suggest the prevalence of sarcopenia PANGASINAN STATE UNIVERSITY 29  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 (9.9% overall: 9.8% among men, and 10.1% among women), providing valuable information in addressing sarcopenia prevention in the older community. A narrative review published in International Journal of Molecular Sciences (2020) provides new evidence regarding the mechanisms, evaluation and detection methods, and spinal sarcopenia treatment modalities. Age-related Changes in Muscle Structure With increasing age, we lose muscle mass: lean muscle mass contributes up to 50% of total body weight in young adults, but this decreases to 25% by 75 to 80 years. Typical muscle changes with age: Reduced muscle mass (replaced by increased fat mass) Reduction in lower limb muscle cross-sectional area have been observed to begin in early adulthood and accelerate beyond 50 years of age.This reduction in muscle cross-sectional area associated with decreases in contractile structures accompanied by increases in non contractile structures such as fat and connective tissue. A cross-sectional study suggested that the older inpatient showed an increase in the intramuscular quadricep muscle adipose tissue approx 1.7 times that of the healthy older individuals. Also, the study observed increased intramuscular adipose tissue with olde r inpatients who were unable to walk independently as compared to older inpatients who were able to walk freely. Reduced muscle strength The total number of muscle fibers is significantly reduced with age, beginning at about 25 years and progressing at an accelerated rate thereafter The decline in muscle cross-sectional area is most likely due to decreases in total fiber number, especially type II fast -twitch glycolytic fibers. This results in reduced muscle power. ] A study examining 1-year changes in the physical functioning of older people using the ICF framework showed a significant decrease in muscle strength (both hip abductors and knee extensors) walking capacity, speed, mobility, sit-to-stand performance, upper extremity function, and balance performance at the end of 1 year. LEARNING ACTIVITY 1. Draw and label the gross anatomy of muscular system. 2. explain how different muscle groups work together to produce movement. 3. Write your name, year, course and section and the date at the upper part of your activity sheets. 4. Prepare your answers and sending it directly in the Learning Management System. PANGASINAN STATE UNIVERSITY 30  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 SUMMARY The muscular system is a set of tissues in the body with the ability to change shape. Muscle cells connect together and eventually to elements of the skeletal system. When the muscle cells contract, force is created as the muscles pull against the skeleton. Actin and myosin are the main proteins used in muscle cells to produce a contraction. These two components use ATP to pull against each other. They attach to each side of the cell, which shortens the cell as they move past each other. The muscular system relies on the coordinated action of millions of actin and myosin filaments pulling in the same direction at the same time. To achieve this coordination, muscles are innervated by the nervous system. There are 3 types of muscles in the body: Skeletal muscle Skeletal muscles are the only muscles that can be consciously controlled. They are attached to bones, and contracting the muscles causes movement of those bones. Any action that a person consciously undertakes involves the use of skeletal muscles. Examples of such activities include running, chewing, and writing. Smooth muscle Smooth muscle lines the inside of blood vessels and organs, such as the stomach, and is also known as visceral muscle. It is the weakest type of muscle but has an essential role in moving food along the digestive tract and maintaining blood circulation through the blood vessels. Smooth muscle acts involuntarily and cannot be consciously controlled. Cardiac muscle Located only in the heart, cardiac muscle pumps blood around the body. Cardiac muscle stimulates its own contractions that form our heartbeat. Signals from the nervous system control the rate of contraction. This type of muscle is strong and acts involuntarily. Main functions of the muscular system Mobility The muscular system’s main function is to allow movement. When muscles contract, they contribute to gross and fine movement. Stability Muscle tendons stretch over joints and contribute to joint stability. Muscle tendons in the knee joint and the shoulder joint are crucial in stabilization. Posture Skeletal muscles help keep the body in the correct position when someone is sitting or standing. This is known as posture. PANGASINAN STATE UNIVERSITY 31  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 Circulation The heart is a muscle that pumps blood throughout the body. The movement of the heart is outside of conscious control, and it contracts automatically when stimulated by electrical signals. Smooth muscle in the arteries and veins plays a further role in the circulation of blood around the body. These muscles maintain blood pressure and circulation in the event of blood loss or dehydration. They expand to increase blood flow during times of intense exercise when the body requires more oxygen. Respiration Breathing involves the use of the diaphragm muscle. The diaphragm is a dome-shaped muscle located below the lungs. When the diaphragm contracts, it pushes downward, causing the chest cavity to get bigger. The lungs then fill with air. When the diaphragm muscle relaxes, it pushes air out of the lungs. When someone wants to breath more deeply, it requires help from other muscles, including those in the abdomen, back, and neck. Digestion The muscular system allows for movement within the body, for example, during digestion or urination. Smooth muscles in the gastrointestinal or GI tract control digestion. The GI tract stretches from the mouth to the anus. Food moves through the digestive system with a wave-like motion called peristalsis. Muscles in the walls of the hollow organs contract and relax to cause this movement, which pushes food through the esophagus into the stomach. The upper muscle in the stomach relaxes to allow food to enter, while the lower muscles mix food particles with stomach acid and enzymes. The digested food moves from the stomach to the intestines by peristalsis. From here, more muscles contract to pass the food out of the body as stool. Urination The urinary system comprises both smooth and skeletal muscles, including those in the:  bladder  kidneys  penis or vagina  prostate  ureters  urethra The muscles and nerves must work together to hold and release urine from the bladder. Urinary problems, such as poor bladder control or retention of urine, are caused by damage to the nerves that carry signals to the muscles. Childbirth Smooth muscles in the uterus expand and contract during childbirth. These movements push the baby through the vagina. Also, the pelvic floor muscles help to guide the baby’s head down the birth canal. PANGASINAN STATE UNIVERSITY 32  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in Sci 120 – ANATOMY and PHYSIOLOGY Module No. 2 Vision Six skeletal muscles around the eye control its movements. These muscles work quickly and precisely, and allow the eye to:  maintain a stable image  scan the surrounding area  track moving objects Organ protection Muscles in the torso protect the internal organs at the front, sides, and back of the body. The bones of the spine and the ribs provide further protection. Muscles also protect the bones and organs by absorbing shock and reducing friction in the joints. Temperature regulation Maintaining normal body temperature is an important function of the muscular system. Almost 85 percent of the heat a person generates in their body comes from contracting muscles. When body heat falls below optimal levels, the skeletal muscles increase their activity to make heat. Shivering is one example of this mechanism. Muscles in the blood vessels also contract to maintain body heat. Body temperature can be brought back within normal range through the relaxation of smooth muscle in the blood vessels. This action increases blood flow and releases excess heat through the skin. REFERENCES Penecilla Gerald, L. Formacion, N. Fandialan, N. Valmote, M. Sandoval, and N. Esmeralda. 2003. Basic Concepts in Biology. Philppines: Trintas Publishing, Inc.. pp 68-73 http://www.ftcollinspersonaltrainer.com/2017/04/different-types-muscle-tissue/ 1http://leavingbio.net/skeleton-muscles/ https://www.researchgate.net/figure/Structure-of-skeletal-muscle-From-Raven-et-al-82-Fig-36 original-in-Sherwood_fig1_266680796 http://grants.hhp.coe.uh.edu/clayne/6397/unit3.htm https://biologydictionary.net/muscular- system/#:~:text=The%20muscular%20system%20is%20a,muscles%20pull%20against%20the%20skeleton https://www.physio-pedia.com/Muscle_Function:_Effects_of_Aging PANGASINAN STATE UNIVERSITY 33