Human Anatomy & Physiology - SKELETAL System PDF

Human Anatomy & Physiology by JULIE ANNE BONITA B. SANCHEZ, RN  Table of contents Anatomy of Skeletal Physiology of 01 02 System Skeletal System 03 Anatomy of Muscular 04 Physiology of System Muscu...

Human Anatomy & Physiology by JULIE ANNE BONITA B. SANCHEZ, RN  Table of contents Anatomy of Skeletal Physiology of 01 02 System Skeletal System 03 Anatomy of Muscular 04 Physiology of System Muscular System Anatomy and Physiology of 05 Integumentary System 01 Anatomy of Skeletal System human skeleton is divided into two 1. AXIAL major divisions 2. APPENDICULAR Consists of the Includes the bones of bones of the the arms, legs, and head, neck, and girdles (the bones that trunk attach the arms and legs to the trunk) CLASSIFICATION OF BONES 1. LONG BONES Longer than they are wide with club-like ends. Examples: Bones of the arms, legs, fingers, and toes 2. SHORT BONES Approximately equal in length and width, cube-shaped. Examples: Wrist bones and proximal foot bones. 3. FLAT BONES Flat resembling a sheet of modeling clay. Examples: Sternum (breastbone), cranial bones, and ribs. 4. IRREGULAR BONES Do not fit into the other categories and have complex shapes with processes, spines, and ridges. Provide attachment points for tendons (attach muscle to bone) and ligaments (attach bone to bone). Examples: Vertebrae; 3 bones in ear: malleus, incus, and stapes 5. SESAMOID BONES Small, seed-like bones that form in tendons where there is a lot of friction. Protect tendons from wear and tear as they slide over bony prominences. Examples: Patellas (kneecaps), which protect the patellar tendon over the knee. AXIAL SKELETON AXIAL SKELETON 1 Cranial 4 Sternum 2 Facial 5 Ribs 3 Spinal Column 6 Hyoid Bone 1. CRANIAL BONES Frontal bone Occipital bone Two temporal bones Two parietal bones Sphenoid Ethmoid Foramina Openings in the skull allowing passages of blood vessels and nerves Occipital bone contains a large opening called the foramen magnum, which allows the spinal cord to exit the cranial cavity External occipital protuberance - a tendon attachment point on the occipital bone, typically larger in males. Ethmoid An irregular forming part of the cranial cavity floor Cribriform plate- contains depressions and many holes for nerve endings from the first cranial nerve to access the nasal Conchae- lateral bony ridges in the nasal cavity Sphenoid Appears butterfly-shaped Sella Turcica- a structure resembling a "Turkish saddle," where the pituitary gland sits. The saddle’s bar surrounds and protects the pituitary gland. 2. FACIAL BONES 1. Nasal Bones (2): Form the bridge of the nose, transitioning to nasal cartilage halfway down. 2. Lacrimal Bones (2): Small bones forming part of the eye socket. 3. Zygomatic Bones (2): Cheekbones that arch to form an arch with the temporal bones. 4. Inferior Nasal Conchas (2): Form the inferior lateral ridges in the nasal cavity. 2. FACIAL BONES 5. Maxillas (2): Form the upper jaw and the anterior hard palate in the mouth cavity. 6. Palatine Bones (2): Contribute to the formation of the eye socket (though often obscured by the maxilla). 7. Mandible (1): The lower jaw, containing the only movable joint in the skull—the temporomandibular joint (TMJ). 8. Vomer (1): Forms the inferior part of the nasal septum, which divides the nostrils. Other important structures: Eye Socket: Formed by seven bones, including the palatine (obscured by the maxilla in diagrams). Nasal Septum: Divides the nostrils into right and left, formed by the vomer (inferior) and ethmoid (superior). Zygomatic Arch: Formed by the zygomatic and temporal bones, allowing muscles to pass deep into it. Hard Palate: Formed by the maxilla and the palatine bones, creating the roof of the mouth cavity. Temporomandibular Joint (TMJ): The joint where the mandible meets the temporal bone, allowing for jaw movement. SINUSES Frontal sinus Ethmoid sinus Sphenoid sinus Maxilla Sinus Cavities within these bones are lined by mucous membranes, filled with air, and named after the bones in which they are located. They help warm and moisten inspired air and add resonance to the voice. 3. SPINAL COLUMN Cervical Vertebrae (7): Located in the neck. Thoracic Vertebrae (12): Located in the upper and mid-back, each connected to a rib. Lumbar Vertebrae (5): Located in the lower back, bearing much of the body's weight. Sacrum (1): A single triangular bone formed by the fusion of five sacral vertebrae. Coccyx (1): Known as the tailbone, formed by the fusion of four small coccygeal vertebrae. Curvature of the Spinal Column Anterior/Posterior View: The spinal column appears as a straight line. Lateral View: The spinal column displays an elongated S-shaped curve. Newborn Spine: Initially has a C-shaped curvature. Cervical Curvature: Develops as an infant starts to crawl and lift its head. Lumbar Curvature: Forms as a toddler begins to walk. The S-shaped curve of the spine is essential for efficient weight distribution and movement, aiding in balance and flexibility. Each vertebra is classified as an irregular bone and has several distinct features: Body: Supports the body's weight. Vertebral Foramen: Allows the spinal cord to pass through. Spinous and Transverse Processes: Serve as attachment points for tendons and ligaments. Intervertebral disk Softer matrix surrounded by fibrocartilage The disks support the body weight and acts as shock absorbers, cushioning the vertebrae from the impact of each footstep. a. Cervical Vertebrae Seven cervical vertebrae have foramina in the transverese processes. Vertabral arteries pass through these opening on their way to the head. Only vertebrae with transverse foramina 1. Atlas – which has a very little body and very large vertebral foramen for the spinal cord. 2. Axis – which has peg-like structure called the odontoid process or dens - This allows you to turn your head to the right and left b. Thoracic Vertebrae 12 thoracic vertebrae are distinctive because they are only vertebrae in the body that have smooth surfaces called costal facets Ribs attach to the facets on the bodies and transverse processes of these vertebrae They are numbered T1 through T12. T1 is the most superior c. Lumbar vertebrae The five lumbar vertebrae are the largest as they bear the body's weight. While T12 and L1 may appear similar in size, T12 has facets for rib attachment, unlike L1. d. Sacrum and coccyx The sacrum and coccyx form the lower end of the spinal column. In a fetus, the sacrum comprises five separate bones that fuse into one in adulthood. Similarly, the coccyx consists of four to five bones that fuse into one. This fusion reduces the spinal column from 33-34 bones in a fetus to 26 in an adult. 4. Sternum Flat bone Composed of three parts 1. manubrium 2. body 3. xyphoid process Serve as a protective plate for the heart and as an attachment site for the ribs encasing the thorax Manumbrium connects the pectoral girdle Xyphoid process the inferior part of the sternum 5. RIBS 12 pairs of ribs Provide protection for the lungs in the thoracic cavity The 7 superior pairs of ribs are connected to the sternum by their coastal cartilages. Pairs 8 through 10 are considered false ribs because they do not have individual costal cartilages connecting them to the sternum. Pairs 11 and 12 are considered false floating ribs because they are not connected to the sternum 6. HYOID BONE is U-shaped bone found in the body’s anterior cervical region between the mandible and the larynx The bone is unique because it is not attached to other bone Muscle attach to the hyoid bone to form the angle between the chin and the neck APPENDICULAR SKELETON The appendicular skeleton includes the bones of the limbs and the girdles that attach them to the axial skeleton. The pectoral girdle connects the arms, and the pelvic girdle connects the legs to the axial skeleton. A. PECTORAL GIRDLE Clavicle and scapula Connect the arm to the axial skeleton 1. CLAVICLE Commonly called the collarbone S-shaped holds the shoulder laterally 2. SCAPULA The shoulder blade with a smooth interior for rib movement and a spine for muscle attachment. It has three lateral features Acromion Process: Joins with the clavicle. Coracoid Process: Muscle attachment point. Glenoid Cavity: Articulates with the humerus. B. BONES OF THE UPPER LIMBS Humerus Radius Ulna Carpal Metarcapals Phalenges 1. Humerus Proximal arm bone with features including: Head: Articulates with the scapula's glenoid cavity. Greater and Lesser Tubercles: Muscle attachment points. Deltoid Tuberosity: Deltoid muscle attachment. Capitulum: Articulates with the radius. Trochlea: Articulates with the ulna. Lateral and Medial Epicondyles: Muscle attachment points. 2. Radius The long bone of the forearm Head: Articulates with the humerus's capitulum. Styloid Process: Frames the wrist's lateral carpal bones 3. Ulna The other long bone of the forearm Olecranon: Fits into the humerus's olecranon fossa. Trochlear Notch: Articulates with the humerus's trochlea. Styloid Process: Frames the wrist's medial carpal bones. 4. Carpal Bones Eight bones in the wrist They form two rows of cubelike bones that allow movement from side to side and front to back 1. Proximal row- scaphoid, lunate, triquetrum, pisiform 2. Distal row- trapezium, capitate, and humate 5. Metacarpals Bones Five metacarpals bone are long bones They make up the palm of the hand The metacarpals are numbered, with 1 being proximal to the thumb and 5 being proximal ti the little finger. 6. Phalenges The 14 phalanges are long bine that up the fingers Named by their position as proximal, middle, or distal, and by the finger in which they reside C. PELVIC GIRDLE Pelvic girdles attach lower limbs to the axial skeleton at the sacrum. Composed of three bones: ilium, ischium, and pubis, collectively known as the ossa coxae, coxal bone, or hip bone. C. PELVIC GIRDLE Ilium- most superior of the pelvic girdle Ischium- most inferior bone of the pelvic girdle Pubis – most anterior bone of the pelvic girdle Acetabalum- lateral socket formed by the fusion of ilium, ischium, and pubis -articulates with the femur D. Bones of the Lower Limb Femur Tibia Fibula Tarsals Metatarsals Phalanges of the foot 1. Femur The femur proximal long bone of the leg Head. A round ball-like structure at the proximal end of the femur. It articulates with the acetabulum of the pelvic girdle. Neck. Connects the head to the bone’s shaft Greater and lesser trochanters. Attachments points for muscles by tendons Medial and lateral condyles. Articulate with the tibia Medial and lateral epicondyles. Attachment sites for muscles by tendons 2. Patella Seasamoid bone in the patellar ligament It protects the patellar ligament from wear and tear as it glides over the femur and tibia at the knee joint 3. Tibia more massive long bones of the lower leg Articulates at the femur at the knee Medial and later condyles. Articulate with the medial and later condyle of the femur at the knee. Tibial tuberosity. It is a roughened area for the attachment of muscles by tendons Anterior crest. Is a sharp ridge running along the anterior shaft of the bone. Commonly referred to as the shin Medial malleolus. It forms the knob of the medial ankle and is an attachment site for the ligament 4. Fibula Less massive long bone of the lower leg Lateral to the tibia and it does not articulate with the femur at the knee Head. Proximal end of the fibula articulates with the tibia Lateral malleolus. Forms the lateral end of the ankle. It is an attachment point for ligaments. It is also anchors the ankle to prevent it from turning laterally. 5. Tarsals Short bones of the ankle and foot Talus. Articulates with the distal end of the tibia Calcaneus. Is the heel bone. The calcaneal tendon attaches the calf muscle to the calcaneus Navicular. Large, wedge-shaped bone Cuneiforms and cuboid. Make up the distal row of tarsals in the foot. The cuboid is the 6. Metatarsal Five metatarsals of bones in the foot Proximal to the toes and distal to the tarsals 7 Phalanges 14 phalenges are long bones that make up the toes Named by their position as proximal, middle or distal and by the toe in which ANATOMY OF LONG BONE Epiphyses Structure: The ends of a long bone, called epiphyses, are covered with articular cartilage made of hyaline cartilage, providing a smooth surface for joint articulation. Composition: Contains cancellous (spongy) bone filled with red bone marrow in the spaces between trabeculae. Diaphysis (Shaft of the Bone) Structure: The diaphysis is a hollow tube of compact bone with a central marrow (medullary) cavity. Contents: Filled with yellow bone marrow, which reduces the bone's weight by being less dense than bone tissue.  Coverings: Periosteum: A fibrous layer that covers the diaphysis and serves as a source of osteoblasts (bone-forming cells). Endosteum: Lines the marrow cavity and provides osteoclasts (bone-resorbing cells). Nutrient Supply: A nutrient artery enters through a foramen in the diaphysis, branching to supply blood to the compact bone's Haversian canals.  Coverings: Periosteum: A fibrous layer that covers the diaphysis and serves as a source of osteoblasts (bone-forming cells). Endosteum: Lines the marrow cavity and provides osteoclasts (bone-resorbing cells). Nutrient Supply: A nutrient artery enters through a foramen in the diaphysis, branching to supply blood to the compact bone's Haversian canals. Bone Marrow 1. Red Bone Marrow: Location: Found in the spaces of cancellous bone, including in flat bones (e.g., sternum), irregular bones (e.g., vertebrae), and the epiphyses of long bones. Function: Composed of stem cells that produce red and white blood cells and platelets. Bone Marrow 2. Yellow Bone Marrow: Location: Found in the marrow cavity of mature long bones. Transformation: Initially red marrow in developing bones, turns into yellow marrow composed mainly of fatty tissue as the bone matures. Function: Reduces the bone's weight and can convert back to red marrow in cases of extreme anemia. Articular Cartilage It provides a smooth surface at the ends of bones for joint movement, facilitating smooth articulation between bones. JOINTS 02 Physiology of Skeletal System MINERAL DEPOSITION BONE DEVELOPMENT  As an infant, most of your skeleton is cartilage. Cartilage is a strong flexible tissue. Over time the cartilage is replaced by solid bone, usually complete by the time you stop growing. Not all cartilage is replaced in adults. Many joints contain cartilage, protecting the ends of the bones (ears and the end of the nose are BONE GROWTH  Bone formation and growth Ossification is the process of bone formation Occurs on hyaline cartilage models or fibrous membranes Long bone growth involves two major phases: 1. Osteoblasts (bone-forming cells) cover hyaline cartilage model with bone matrix 2. In a fetus, the enclosed cartilage is digested away, opening up a medullary cavity TYPES OF BONE CELLS Osteogenic cells or osteoprogenitor cells, are mitotically active stem cells found in the membranous periosteum and endosteum. Osteocytes—mature bone cells; monitor and maintain the bone matrix Osteoblasts—bone-forming cells Osteoclasts—giant bone-destroying cells Break down bone matrix for remodeling and release of calcium in response to parathyroid hormone Bone remodeling is performed by both osteoblasts and  By birth, most cartilage is converted to bone except for two regions in a long bone 1. Articular cartilages 2. Epiphyseal plates New cartilage is formed continuously on the external face of these two cartilages Old cartilage is broken down and replaced by bony matrix  Appositional growth (growth from outside) Bones grow in width Osteoblasts in the periosteum add bone matrix to the outside of the diaphysis Osteoclasts in the endosteum remove bone from the inner surface of the diaphysis Interstitial growth (growth from within) Bones expands Lacunae bound chondrocytes divide and secrete new matrix BONE REMODELING ▪Bones are remodeled throughout life in response to two factors: 1. Calcium ion level in the blood determines when the bone matrix is to be broken down or formed. 2. The pull of gravity and muscles on the skeleton determines where the bone matrix is to be broken down or formed. ▪Calcium ion regulation ▪Parathyroid hormone (PTH) Released when calcium ion levels in blood are low Activates osteoclasts (bone-destroying cells) Osteoclasts break down bone and release calcium ions into the blood ▪Hypercalcemia (high blood calcium levels) prompts calcium storage to bones by osteoblasts NUTRITIONAL REQUIREMENTS OF THE SKELETAL SYSTEM  Dairy products are a major dietary source of calcium, and the calcium content remains unaffected by removing fat from these products. Active vitamin D, or calcitriol, is essential for the absorption of calcium from the diet through the small intestines. Vitamin D (Calcitriol) Vitamin D is produced in the skin and is converted to its active form, calcitriol, by the liver and kidneys. Calcitriol is crucial for the absorption of dietary calcium in the small intestines. Without calcitriol, calcium from food would pass through the digestive system without being absorbed into the bloodstream. Calcium Dairy products are rich in calcium. Since calcium is not found in the fat portion, low-fat dairy products still provide significant calcium. Green leafy vegetables like broccoli, collards, kale, turnip greens, and bok choy also contain calcium. To enhance calcium absorption, vitamin D is Phosphorus Phosphorus, needed for phosphate formation in bones, is abundant in dairy products and meats. Unlike calcium, phosphorus does not require vitamin D for absorption in the small intestines. Nutrition and Bone Health Proper nutrition, including adequate intake of calcium and phosphorus, is essential for maintaining bone homeostasis and promoting healthy bone development. Ensuring sufficient levels of vitamin D, either through diet, supplementation, or sunlight exposure, is critical for optimal calcium absorption and bone health. HORMONAL REGULATION OF BONE DEPOSITION AND REABSORPTION FUNCTIONS OF SKELETAL SYSTEM SUPPORT The skeletal system provides structural support for the body. As individuals develop, their bones grow and adapt to support their weight. MOVEMENT Bones and joints facilitate movement The spinal column's 26 bones and the joints between them enable a range of motions, such as touching toes. Similarly, joints in the arms allow for complex movements like touching the tip of the nose. PROTECTION Bones protect vital organs. Skull formed through intramembranous ossification, protects her brain. Ribs and sternum shield lungs and heart, while vertebrae protect the spinal cord. Additionally, the sella turcica developed to give added protection to pituitary gland ACID-BASE BALANCE Bones help maintain blood pH within the normal range (7.35 to 7.45). In cases of acidosis (low blood pH), phosphate ions from bones bind to excess hydrogen ions, acting as a buffer to stabilize the pH level. ELECTROLYTE BALANCE Bones serve as a reservoir for calcium, crucial for maintaining homeostasis. When dietary calcium intake is sufficient, it is absorbed into the bloodstream and stored in bones if blood levels are high. Conversely, if dietary intake is low, calcium is reabsorbed from bones to maintain normal blood levels. BLOOD FORMATION Blood Formation: Red and white blood cells, along with platelets, are produced by stem cells in the red bone marrow, located within certain bones. 03 ANATOMY OF MUSCULAR SYSTEM TERMS OF MUSCLE ATTACHMENTS Origin the attachment of a muscle to a bone structure that does not move when the muscle contracts. A muscle has an attachment to a bone or another structure at each end. One attachment must be anchored for the muscle to be able to pull at the other end. The origin is the site of the anchored end. Insertion the attachment of a muscle to a bone or structure that does move when the muscle contracts. Intrinsic Muscle a muscle that has its origin and insertion located in the same body region. Example: The temporalis muscle is intrinsic to the head because its origin and insertion are both in the head. Extrinsic muscle a muscle that has its origin located in a body region different from that of its insertion. Example: The sternocleidomastoid muscle is extrinsic to the head because its origin is in the head but its insertion is in the thorax. Extrinsic muscle a muscle that has its origin located in a body region different from that of its insertion. Example: The sternocleidomastoid muscle is extrinsic to the head because its origin is in the head but its insertion is in the thorax. TERMS THAT INDICATE THE INTERRELATED ACTIONS OF MUSCLES Fixator a muscle that holds an origin stable for another muscle. Synergists Muscles that have the same action Prime mover The main muscle that acts, helped by synergists Antagonist A muscle that has an opposition action MUSCLE ACTIONS Flexion Action that bends a part of the body anteriorly, such as flexing the elbow To flex the arm is to bring the entire arm to pint something ahead of you. Extension Action that bends apart of the body posteriorly, such as staiggthening the arm at the elbow Abduction movement of a part of the body away from the midline. Adduction Movement of a part of the body toward the midline Protraction Movement that brings part of the body forward Retraction Movement of the body that brings part of the body backward Lateral Excursion Movement of the jaw laterally to either sideExcursion Movement of the jaw Medial back to the midline Dorsiflexion Position of standing on the heels with the toes pointing up off the floor Plantar Flexion Position of standing on tiptoes with the heels off the floor Inversion Position in which the soles of the feet are together, facing each Eversion Position other in which the soles of the feet point away from each other. Rotation the act of spinning on an axis. Pointing your toes to the side involves rotation of the leg Circumduction The act of making a circle with part of the body. A baseball or softball pitch involves circumduction at the shoulder. Supination rotation that turns the palms up. You could hold soup in the palm ofyour hand when your palm is supinated Pronation rotation that turns the palms down. You would pour soup from yourhand during pronation. Opposition the act of bringing the thumb to the palm. Repostion the act of taking the thumb away from the palm. Elevation the act of closing the jaw or raising the shoulders. Depression the act of opening the jaw or lowering the shoulders MUSCLES BY REGION ANATOMY OF SKELETAL MUSCLE Anatomy of Skeletal Muscle A muscle has a fibrous covering called the epimysium A muscle is composed of a bundle of fascicles Each fascicle is surrounded by perimysium A fascicle is composed of muscle cells (muscle fibers)surrounded by endomysium The connective tissues of the muscle come together at the end of the muscle cell, or fiber, to form a tendon. Connective Tissues and Structural Components of Thigh Muscle Connective Tissues and Structural Components of Thigh Muscle Anatomy of Skeletal Muscle Cell Sarcolemma is the plasma membrane The sarcoplasmic reticulum is the name given to the smooth endoplasmic reticulum in a muscle cell stores calcium ions Anatomy of Skeletal Muscle Cell A muscle cell is composed of myofibrils Each myofibril is composed of thick and thin Myofilaments arranged in sarcomeres. Thick and thin myofilaments are composed of protein molecules. STRUCTURE OF THE MUSCLE FIBER Anatomy of Skeletal Muscle Cell Each myofibril consists of repeating contractile units called sarcomeres Sarcomere extends from Z line to Z line Actin filaments are attached to Z lines and extend towards the center of the sarcomere but do not meet. Myosin filaments reside in the A band and do not contact the Z lines.  Muscle Fiber (Cell) Striations and Sarcomeres Anatomy of Skeletal Muscle Cell Thick myofilament Myosin subunits look like a doubleheader golf club. Head is referred to as a cross-bridge. Thin myofilament Actin subunits make up a double chain of beads twisted together. Tropomyosin is a thread that holds the actin chained together. Troponin is a calcium regulatory molecule PROTEIN STRUCTURE OF THIN AND THICK FILAMENTS 04 PHYSIOLOGY OF MUSCULAR SYSTEM PHYSIOLOGICAL CHARACTERISTICS OF MUSCLE TISSUE Excitability A muscle cell can be stimulated by a nerve to contract Conductivtity The stimulation from the nerve moves quickly along the length of the muscle Contractility A muscle cell can shorten with force. Muscle can oly pull; they cannot push Extensibility A muscle cell can be stretched. If the biceps brachii contracts to flex the arm, the triceps brachii needs to stretch to accommodate the motion. Muscles are stretched by the contraction of other Elasticity muscles. If a muscle cell is stretched, it will return to its original shape. NEUROMUSCULAR JUNCTION Neuromuscular Junction Stimulation of a muscle cell by a nerve happens at a neuromuscular junction. Generically referred to as a synapse. An electrical stimulation along the nerve cell results in the release of a acetylcholine. Acetylcholine fits into receptors on the muscle cell to stimulate it to contract A NEUROMUSCULAR JUNCTION Neuromuscular Junction A minimal amount of stimulus called a threshold is needed for the muscle to respond As long as the threshold is reached, the muscle cell will contract in an all-or-nothing manner. MUSCLE CONTRACTION AT THE MOLECULAR LEVEL Muscle Contraction at the Molecular Leve The sliding filament theory of muscle contraction involves thick myofilaments grabbing thin myofilaments and pulling them toward the center of the sarcomere. As all of the sarcomeres are shortened, so too is the muscle cell. Muscle Contraction at the Molecular Leve Energy contained in ATP is needed for the contraction to happen and to actively transport calcium ions back to the sarcoplasmic reticulum so that the muscle can relax. Steps of Muscle Contraction 1. Initiation by Electrical Impulse -An electrical impulse travels down the neuron. -Acetylcholine (ACh) is released from the synaptic knob of the neuron and binds to receptors on the relaxed muscle cell Steps of Muscle Contraction 2. Calcium Release: The binding of ACh triggers the sarcoplasmic reticulum to release calcium ions. Calcium ions bind to troponin, causing tropomyosin to move aside and uncover active sites on actin. 3. Myosin Cross-Bridge Attachment: Myosin cross-bridges, already energized with ATP from a previous contraction, grab hold of the exposed active sites on actin. 4. Power Stroke: Myosin pulls on actin, called the power stroke, drawing the Z lines closer together and shortening the sarcomere. During this process, ADP and a phosphate group (P) are released from myosin. 5. Detachment and Re-Energizing: A new ATP molecule binds to myosin, causing it to release the active site on actin. The ATP molecule is then split, providing energy to "cocked" the myosin cross-bridge for the next power stroke. 6. Relaxation For muscle relaxation, calcium ions must be actively transported back into the sarcoplasmic reticulum, requiring ATP. Tropomyosin covers the active sites on actin again, preventing myosin from binding. 7. Acetylcholine Removal: Acetylcholine must be removed from the receptors at the neuromuscular junction to stop the release of calcium ions. The enzyme acetylcholinesterase breaks down acetylcholine, ensuring the muscle cell remains relaxed. FATIGUE  Fatigue is the inability of a muscle to fully respond to a nerve stimulus. Physiological contracture is complete fatigue in which the muscle appears to be stuck. It can no longer relax Fatigue can result from the build up of lactic acid, the lack of acetylcholine, or the lack of glucose The amount of glocuse needed to remove the lactice acid is called oxygen debt. Fatigue Slow-twitch fibers are specialized for aerobicrespiration, so they do not fatigue quickly. Fast-twitch fibers are specialized for anaerobicrespiration and therefore fatigue quickly NUTRITIONAL REQUIREMENT OF MUSCLE TISSUE  Muscle tissue must maintain the proteins needed for contraction. Therefore, amino acids, the building blocks of protein, must be included in the diet.  The body can make nonessential amino acids Essential amino acids must be supplied through the diet. Complete proteins have all of the amino acids. Incomplete proteins are missing one or more essential amino acids. The mineral potassium is also needed for proper muscle function. COMPARISON OF MUSCLE TISSUES FUNCTIONS OF THE MUSCULAR SYSTEM IN EVERYDAY ACTIVITIES 1. Movement A gradual recruitment of additional motor units makes a smooth contraction. 2. Stability Some of the motor units in the trapezius muscle aretaking turns in isometric contractions to maintain thestability of the head. This is called muscle tone. A person’s 3. Control of body openings and passages Urinary and anal sphincters are under a person’s voluntary control. 4. Communication Facial muscles can be used to communicate. Muscles in the throat, jaw, tongue, and diaphragm are used to communicate through speech. 5. Heat Production Muscles provide body heat 05 ANATOMY AND PHYSIOLOGY OF INTEGUMENTARY SYSTEM  The skin is the body's largest organ, making up approximately 15% of the body's total weight. The epidermis is the skin's most superficial layer, made up of stratified squamous epithelial tissue. Beneath the epidermis is the dermis, composed of loose/areolar connective tissue over dense irregular connective tissue.  The dermis contains cutaneous glands, hair follicles, and most of the skin's nerve endings. Deep to the dermis is the hypodermis, or subcutaneous layer, which attaches the skin to the rest of the body. The hypodermis is mainly composed of adipose connective tissue, serving as an insulating layer, cushioning layer, and energy source. This layer is generally thicker in women than in men. EPEDERMIS Epidermis Structure and Cell types Is the superficial layer of the skin Divided into five general layers called strata: 1. Stratum Basale 2. Stratum Spinosum 3. Stratum Granulosum 4. Stratum Lucidum 5. Stratum Corneum Epidermis Structure and Cell types Cells of the epidermis: 1. Keratinocytes 2. Melanocytes 3. Tactile Cells 4. Dendritic Cells 1. Stratum Basale Location: Deepest layer, adjacent to the dermis. Characteristics: Contains a single layer of cuboidal cells that actively grow and divide to produce new epidermis. Dips into the dermis to form hair  2. Stratum Spinosum Location: Superficial to the stratum basale. Characteristics: Provides strength and flexibility to the skin. 3. Stratum Granulosum: Location: Above the stratum spinosum. Characteristics: Contains granules that release lipids to waterproof the skin. 4. Stratum Lucidum: Location: Found only in thick skin (e.g., palms and soles). Characteristics: A clear, thin layer that provides an additional barrier.  5. Stratum Corneum: Location: Most superficial layer. Characteristics: Composed of up to 20 layers of dead, tough, waterproof cells that eventually flake off (exfoliate).  Cells of the Epidermis 1. Keratinocytes Function: Make up the majority of epidermal cells. These cells grow and divide in the stratum basale, pushing older cells toward the surface. Process: As they move up, they produce and fill with keratin, eventually dying and forming the durable stratum corneum through a process called cornification.  Cells of the Epidermis 2. Melanocytes Function: Produce melanin, the pigment responsible for skin color. Location: Located in the stratum basale with projections extending to more superficial layers. Keratinocytes take in melanin via endocytosis of melanin-filled vesicles (melanosomes). Characteristics: Uneven distribution can lead to freckles and moles.  Cells of the Epidermis 3. Tactile Cells: Function: Serve as receptors for fine touch. Location: Found in the stratum basale and associated with nerve cells in the underlying dermis.  Cells of the Epidermis 3. Dendritic Cells: Function: Act as immune system cells, alerting the body to pathogens. Location: Found in the stratum spinosum and stratum granulosum. DERMIS Papillae These are bumps on the superficial edge of the dermis, in contact with the epidermis. Papillae form unique patterns like fingerprints and provide nutrients to the cells of the basal layer. Their blood vessels reduce the risk of blood loss in case of epidermal injury. Fibers The dermis transitions from loose to dense irregular connective tissue. It contains collagen fibers for strength and elastin fibers for elasticity, allowing the skin to return to shape after stretching. Nutrition Vitamin A and C are vital for collagen production, and their intake through diet contributes to healthy skin, aiding in maintaining homeostasis. Nutrition Vitamin A and C are vital for collagen production, and their intake through diet contributes to healthy skin, aiding in maintaining homeostasis. Nerve Endings Nerve cells in the dermis act as receptors for warmth, cold, pain, and pressure. They include receptors like lamellar and tactile corpuscles and those associated with hair follicles. Cutaneous Glands Exocrine glands, including sebaceous and sweat glands, are distributed throughout the dermis. Sebaceous glands produce sebum to moisturize the skin and hair, while sweat glands secrete sweat to regulate body temperature. Sebaceous Glands Sebaceous glands are linked to hair follicles, with ducts leading to the hair root. They produce sebum, an oily, lipid-rich substance that moisturizes the skin and hair. Sebum travels from the hair follicle to the skin’s surface with the emerging hair. Sebum can be washed off the skin using soap. After cleansing, moisture balance can be restored by applying a lanolin-containing lotion, where lanolin is a form of sebum produced by sheep. Sebaceous Glands cont’d Hormones and Sebum Production Estrogen and testosterone increase sebum production. Hormone levels, particularly during puberty, cause sebaceous glands to become more active, producing more sebum. Sebaceous Glands cont’d Comedo Formation Excess sebum and cells from the sebaceous gland can plug the short ducts delivering sebum to the hair follicle. The gland continues to produce sebum even if the duct is plugged, preventing sebum from reaching the surface. This plug results in a comedo, which can appear as a whitehead or a blackhead if the plug reaches the surface. Sebaceous Glands cont’d Acne Development P. acnes bacteria, which normally live on the skin, can grow in the plugged follicles due to the presence of oil and excess cells. This bacterial growth causes inflammation, potentially leading to the breakdown of the hair follicle wall. If inflammation persists, pus may form, resulting in a pimple, a condition known as acne. Sweat Glands There are several types of sweat glands in the dermis, differing in location, product, and function. Merocrine sweat glands are the most numerous sweat glands in the body. Merocrine sweat contains lactic acid, giving it a pH range of 4 to 6. This acidic pH forms an acid mantle on the skin, which helps reduce bacterial growth. This process is an example of homeostasis, where maintaining the appropriate skin pH contributes to overall skin health. Hair Follicles These are essential for the integumentary system's functioning. They contain keratinocytes and melanocytes producing hair and its pigment. Dermal papilla, located at the follicle base, supports hair growth with vital nutrients. The arrector pili muscle, associated with hair follicles, contracts to create goosebumps in humans. HAIR 3 types of hair on human body 1. Lanugo hair Hair is very fine and unpigmented (colorless), forms on a fetus during the last 3 months of its development. This hair is usually replaced by birth. 2. Vellus hair which is also unpigmented and very fine replaces Replaces lanugo hair around the time of birth 3 types of hair on human body 3. Terminal Hair Which is thick, coarse heavily pigmented, forms the eyebrows, eyelashes, and hair on the scalp. At puberty, terminal hair forms in the axillary and pubic regions of both sexes. It also forms on the face and possibly of the trunk and limbs of men. Human hair divided into three sections: 1. Bulb Is a thickening of the hair at the end of the hair follicle. 2. Roots Extends from the bulb to the skin’s surface 3. Shaft Is the section of the hair extending out from the skin’s surface Hair texture depends on the shaft 1. Straight hair Has round shaft 2. Wavy hair Oval shaft 3. Curly hair Flatter shaft Hair Life Cycle Consists of growing, resting, and dying stages. Each hair grows about half an inch per month, with a growth stage lasting approximately 3 years, followed by a 1 to 2 year resting stage before falling out. Not all hairs cycle at the same time; roughly 90% are in the growing stage at any given time. Normal hair loss is around 100 hairs per day, with eyelashes following a similar cycle of growth, rest, and shedding They grow for about 30 days, rest for 105 days, and then fall out. NAILS Structure: 1. Nail Root Covered by skin and not visible, this is where nail growth begins. 2. Nail Plate: The visible part of the nail, consisting of the free edge, nail body, and lunula (white crescent). 3. Nail Bed: The area underneath the nail plate, appearing pink due to numerous blood vessels in the dermis. 4. Nail Fold: Skin rises laterally to form a fold over the nail's edge. Structure: 5. Nail Groove Where the nail fits into the surrounding skin. 6. Eponychium (Cuticle) A layer of stratum corneum cells extending onto the nail bed at the proximal edge of the nail body. 7. Nail Matrix The growth center of the nail, composed of active keratinocytes in the stratum basale. Functions of nails: Nails protect the fingertips and toe tips. They aid in grasping small objects and are used for scratching. FUNCTIONS OF THE SKIN 1.Protection 2. Vitamin D production 3. Temperature regulation 4. Sensation 5. Nonverbal communication 6. Water Retention Protection The skin acts as a barrier against pathogens, with the stratum corneum making it difficult for bacteria to enter. Dendritic cells in the epidermis guard against pathogens that breach the surface. Melanocytes produce melanin in response to UV exposure, protecting underlying cells from DNA damage. Temperature Regulation The skin helps regulate body temperature through mechanisms like vasodilation and sweating. Vasodilation increases blood flow to dissipate heat, while sweating facilitates evaporative cooling. These processes maintain the body's core temperature within a narrow range through negative feedback regulation. Sensation Nerve endings in the skin constantly send signals to the brain, conveying sensations like temperature, pressure, and pain. Sensory receptors help individuals perceive and respond to their environment. Nonverbal Communication The condition of the skin and hair can convey nonverbal messages about emotions, health, and social acceptance. Changes in skin color, texture, and appearance may reflect emotional states or overall health. Water Retention The epidermis waterproofs the body, preventing water loss and maintaining fluid balance. Immersion in water may cause temporary wrinkling of the skin due to osmosis, especially in areas prone to abrasions.