Bones and Skeletal Tissues Quiz
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Questions and Answers

What term describes a large rounded projection on a bone?

  • Epicondyle
  • Tuberosity (correct)
  • Crest
  • Trochanter

    • Which bone marking is characterized as a smooth, flat articular surface?

  • Fossa
  • Foramen
  • Meatus
  • Facet (correct)

    • What is the term for a shallow, basin-like depression for articulation in bone anatomy?

  • Fossa (correct)
  • Sinus
  • Groove
  • Tubercle

    • Which term describes a round or oval opening in a bone?

    <p>Foramen</p> Signup and view all the answers

    What is the correct name for a small rounded projection found on bones?

    <p>Tubercle</p> Signup and view all the answers

    What is a primary function of bones in the skeletal system?

    <p>Support and protection</p> Signup and view all the answers

    Which type of cartilage is known for its slight flexibility and is the most abundant type?

    <p>Hyaline cartilage</p> Signup and view all the answers

    What is the primary structural component of hyaline cartilage?

    <p>Collagen and elastin fibers</p> Signup and view all the answers

    Which characteristic is NOT associated with cartilage?

    <p>Contains blood vessels</p> Signup and view all the answers

    Which type of bone is described as dense and forms the outer layer of bones?

    <p>Compact bone</p> Signup and view all the answers

    What percentage of water is found in cartilage?

    <p>80%</p> Signup and view all the answers

    Which process is essential for maintaining healthy bone structure over time?

    <p>Bone remodeling</p> Signup and view all the answers

    Which of the following is NOT a function of bones?

    <p>Energy metabolism</p> Signup and view all the answers

    Which type of cartilage contains a large number of elastic fibers?

    <p>Elastic cartilage</p> Signup and view all the answers

    Fibrocartilage is primarily found in which of the following structures?

    <p>Intervertebral discs</p> Signup and view all the answers

    What is the main difference between appositional and interstitial growth of cartilage?

    <p>Appositional growth adds layers to the surface; interstitial growth expands from within.</p> Signup and view all the answers

    Which statement best describes fibrocartilage?

    <p>It resists high pressure and is abundant in collagen.</p> Signup and view all the answers

    Which of the following bones is classified as a short bone?

    <p>Carpal bones</p> Signup and view all the answers

    What key structural unit makes up compact bone?

    <p>Osteon</p> Signup and view all the answers

    What distinguishes spongy bone from compact bone?

    <p>Spongy bone has a porous, lattice-like structure.</p> Signup and view all the answers

    What type of growth primarily involves chondroblasts secreting new matrix on the outer surface?

    <p>Appositional growth</p> Signup and view all the answers

    Which of the following is NOT found in an osteon?

    <p>Trabeculae</p> Signup and view all the answers

    Which classification of bone includes the vertebrae?

    <p>Irregular bones</p> Signup and view all the answers

    What structure connects the lacunae in bone tissue?

    <p>Canaliculi</p> Signup and view all the answers

    Which type of cartilage is primarily found in the larynx?

    <p>Elastic cartilage</p> Signup and view all the answers

    Which type of bone development involves the differentiation of mesenchymal cells into osteoblasts?

    <p>Intramembranous ossification</p> Signup and view all the answers

    What is the primary function of osteoblasts in bone tissue?

    <p>Forming the bone matrix</p> Signup and view all the answers

    What primarily characterizes compact bone?

    <p>It is dense and heavy.</p> Signup and view all the answers

    How do bones become denser during growth?

    <p>By the action of osteoblasts adding bone matrix</p> Signup and view all the answers

    Which structure is characteristic of spongy bone rather than compact bone?

    <p>Trabeculae</p> Signup and view all the answers

    What is the role of fontanelles in skull development?

    <p>Facilitating brain growth</p> Signup and view all the answers

    Which statement about endochondral ossification is true?

    <p>It begins with the formation of a cartilaginous template.</p> Signup and view all the answers

    Which of the following best describes interstitial lamellae?

    <p>Remnants of older osteons between newer ones</p> Signup and view all the answers

    What is the process of endochondral ossification primarily responsible for?

    <p>Ossifying hyaline cartilage</p> Signup and view all the answers

    At what stage does the perichondrium become vascularized during endochondral ossification?

    <p>At about 8 weeks</p> Signup and view all the answers

    In which zone of the epiphyseal plate does new cartilage form before being converted into bone?

    <p>Zone of proliferation</p> Signup and view all the answers

    Which hormone is involved in increasing blood calcium levels?

    <p>Parathyroid hormone (PTH)</p> Signup and view all the answers

    What is the primary function of osteoclasts in bone growth?

    <p>Resorbing bone tissue</p> Signup and view all the answers

    Which of the following fractures is characterized by a break that occurs at a joint?

    <p>Colle's fracture</p> Signup and view all the answers

    What is the term for the transition zone between the diaphysis and epiphysis after growth has concluded?

    <p>Epiphyseal line</p> Signup and view all the answers

    Which of the following is a potential consequence of low calcium levels in the body?

    <p>Osteomalacia</p> Signup and view all the answers

    During bone growth in width, which cells are responsible for bone formation?

    <p>Osteoblasts</p> Signup and view all the answers

    What type of fracture occurs when the bone is crushed under pressure?

    <p>Compression fracture</p> Signup and view all the answers

    Which bones are included in the upper limbs of the appendicular skeleton?

    <p>Humerus, Radius, Ulna, Phalanges</p> Signup and view all the answers

    What is a component of the hip girdle in the appendicular skeleton?

    <p>Coxal bone</p> Signup and view all the answers

    Which of the following bones is part of the lower limbs?

    <p>Fibula</p> Signup and view all the answers

    Which statements about the shoulder girdle are accurate?

    <p>Comprises the clavicles and scapulae</p> Signup and view all the answers

    Which of the following correctly identifies the bones in the lower limb?

    <p>Femur, Tibia, Fibula, Tarsals</p> Signup and view all the answers

    What does the axial skeleton primarily consist of?

    <p>Bones arranged along the longitudinal axis of the body</p> Signup and view all the answers

    Which of the following bone types forms the framework of the face?

    <p>Facial bones</p> Signup and view all the answers

    Which of the following bones is NOT considered a cranial bone?

    <p>Maxilla</p> Signup and view all the answers

    What is one of the primary functions of the cranial bones?

    <p>Enclosing the brain</p> Signup and view all the answers

    Which bones are classified as facial bones?

    <p>Zygomatic and nasal</p> Signup and view all the answers

    What does the appendicular skeleton include?

    <p>Appendages and girdles</p> Signup and view all the answers

    Which of the following is a function of facial bones?

    <p>Providing structural support for the face</p> Signup and view all the answers

    Which of the following bones is part of the cranial vault?

    <p>Parietal</p> Signup and view all the answers

    Which bones are involved in the anterior cranial fossa?

    <p>Frontal, ethmoid, and sphenoid</p> Signup and view all the answers

    Which cranial fossa holds the temporal lobes of the brain?

    <p>Middle fossa</p> Signup and view all the answers

    What is the primary function of fontanels in an infant's skull?

    <p>To enable the skull to compress during birth</p> Signup and view all the answers

    What are sutures in the context of the skull?

    <p>Immovable joints between skull bones</p> Signup and view all the answers

    What is craniosynostosis?

    <p>A condition where one or more sutures close prematurely</p> Signup and view all the answers

    Which sutures are present in the human skull?

    <p>Coronal, sagittal, lambdoid, and squamous</p> Signup and view all the answers

    Which of the following is NOT a major fontanel in infants?

    <p>Maxillary fontanel</p> Signup and view all the answers

    What do tiny bones found within sutures represent?

    <p>Additional ossification centers in expanding skull</p> Signup and view all the answers

    What is the role of the posterior fossa?

    <p>To hold the cerebellum and brain stem</p> Signup and view all the answers

    What is the primary purpose of the paranasal sinuses?

    <p>To lighten the skull and act as resonating chambers</p> Signup and view all the answers

    What is sinusitis primarily caused by?

    <p>Allergies or infections leading to inflammation</p> Signup and view all the answers

    Which of the following conditions results from a lack of fusion of the palatine and maxillary bones during fetal development?

    <p>Cleft palate and cleft lip</p> Signup and view all the answers

    How many regions is the vertebral column distributed into?

    <p>Five regions</p> Signup and view all the answers

    What contributes to the strength and support of the vertebral column?

    <p>Curvatures of the vertebral column</p> Signup and view all the answers

    Which of the following are the primary curvatures of the vertebral column?

    <p>Thoracic and sacral</p> Signup and view all the answers

    What condition is characterized by abnormal development of the spinal column and can lead to incomplete closure of the spine?

    <p>Spina bifida</p> Signup and view all the answers

    Which sinuses are known to potentially cause pain due to blockage of their outlets?

    <p>Both A and B</p> Signup and view all the answers

    What is a common sign of sinusitis?

    <p>Painful pressure build-up in the sinuses</p> Signup and view all the answers

    What role do the paranasal sinuses play in speech?

    <p>They act as resonating chambers.</p> Signup and view all the answers

    What is the primary function of the annulus fibrosus in intervertebral discs?

    <p>To hold successive vertebrae together and resist tension</p> Signup and view all the answers

    What happens when the annulus fibrosus ruptures in a herniated disc?

    <p>The nucleosus pulposus protrudes and may compress nerves</p> Signup and view all the answers

    What distinguishes the atlas from other cervical vertebrae?

    <p>It has no body (centrum)</p> Signup and view all the answers

    Which of the following is NOT a type of rib?

    <p>Decorative ribs</p> Signup and view all the answers

    What is a characteristic of intervertebral discs?

    <p>They have two main components: the inner nucleosus pulposus and the outer annulus fibrosus</p> Signup and view all the answers

    What is the role of the nucleosus pulposus in intervertebral discs?

    <p>Acts as a shock absorber and allows spinal motion</p> Signup and view all the answers

    How do vertebrae primarily differ from each other?

    <p>They have differing body shapes and sizes</p> Signup and view all the answers

    Which characteristic is true about thoracic ribs compared to other rib types?

    <p>They articulate with the sternum via costal cartilages</p> Signup and view all the answers

    What structural feature is unique to the cervical vertebrae?

    <p>Dens or odontoid process in the axis</p> Signup and view all the answers

    What characterizes rheumatoid arthritis?

    <p>It often results in stiffness and deformation of fingers.</p> Signup and view all the answers

    Which special movement involves the rotation of the palm to face upward?

    <p>Supination</p> Signup and view all the answers

    What is the main distinction between osteoarthritis and rheumatoid arthritis?

    <p>Osteoarthritis is known as 'wear-and-tear' arthritis.</p> Signup and view all the answers

    Which of the following conditions is characterized by inflammation of the joints?

    <p>Bursitis</p> Signup and view all the answers

    What does a sprain involve?

    <p>Stretching or tearing of ligaments.</p> Signup and view all the answers

    What type of joint is primarily characterized by the absence of a joint cavity?

    <p>Fibrous joints</p> Signup and view all the answers

    Which type of classification is based on the movement allowed at a joint?

    <p>Functional classification</p> Signup and view all the answers

    What type of fibrous joint allows only slight movement?

    <p>Syndesmoses</p> Signup and view all the answers

    Which type of joint is formed by hyaline cartilage uniting two bones?

    <p>Synchondrosis</p> Signup and view all the answers

    Which type of joint allows for the most movement?

    <p>Diarthroses</p> Signup and view all the answers

    What is the primary characteristic of gomphoses?

    <p>Connects the teeth to their sockets</p> Signup and view all the answers

    What type of cartilaginous joint is found in the pelvis and vertebral column?

    <p>Symphysis</p> Signup and view all the answers

    Which type of joint allows for considerable movement due to the length of the connecting ligament?

    <p>Syndesmoses</p> Signup and view all the answers

    What type of movement occurs between the carpals and tarsals?

    <p>Gliding movement</p> Signup and view all the answers

    Which movement allows for flexion and extension?

    <p>Angular movement</p> Signup and view all the answers

    What characterizes uniaxial movements?

    <p>Movement in one plane only</p> Signup and view all the answers

    Which joint movement involves turning a bone around its own axis?

    <p>Rotational movement</p> Signup and view all the answers

    Which type of movement is classified as multiaxial?

    <p>Circumduction</p> Signup and view all the answers

    What movement is specifically described as decreasing the angle between body parts?

    <p>Flexion</p> Signup and view all the answers

    Which of the following movements is NOT a type of angular movement?

    <p>Gliding</p> Signup and view all the answers

    What is the primary feature of nonaxial movements?

    <p>No defined axis of movement</p> Signup and view all the answers

    Which of the following is an example of a rotational movement?

    <p>Medial rotation of the femur</p> Signup and view all the answers

    Which movement involves the distal end of a limb tracing a circular path?

    <p>Circumduction</p> Signup and view all the answers

    What type of joint is characterized by articulating bones being separated by a fluid-filled cavity?

    <p>Synovial joint</p> Signup and view all the answers

    Which component of synovial joints provides a smooth surface for the opposing bone surfaces?

    <p>Hyaline cartilage</p> Signup and view all the answers

    What is the function of articular discs or menisci in synovial joints?

    <p>Separate the articular surfaces of bones</p> Signup and view all the answers

    Which type of ligaments provide strength and are often found outside the joint capsule?

    <p>Extracapsular ligaments</p> Signup and view all the answers

    What structure is closely associated with synovial joints and is filled with lubricant?

    <p>Bursa</p> Signup and view all the answers

    Which component is NOT part of the synovial joint structure?

    <p>Hyaline membrane</p> Signup and view all the answers

    'Fat pads' in synovial joints serve what purpose?

    <p>Cushion joints</p> Signup and view all the answers

    Which layer of the joint capsule is responsible for producing synovial fluid?

    <p>Inner layer</p> Signup and view all the answers

    What characteristic distinguishes intracapsular ligaments from other types of ligaments in synovial joints?

    <p>They are covered with synovial membrane</p> Signup and view all the answers

    What is the primary function of synovial fluid within a synovial joint?

    <p>Facilitate movement and reduce friction</p> Signup and view all the answers

    What type of ligament is the patellar ligament classified as?

    <p>Extracapsular ligament</p> Signup and view all the answers

    Which type of joint allows for uniaxial movement and permits only flexion and extension?

    <p>Hinge joint</p> Signup and view all the answers

    What characterizes a pivot joint?

    <p>Allows uniaxial rotational movement</p> Signup and view all the answers

    Which of the following describes a ball-and-socket joint?

    <p>Multiaxial and freely movable</p> Signup and view all the answers

    What type of joint is the carpo-metacarpal joint in the thumb classified as?

    <p>Saddle joint</p> Signup and view all the answers

    Which ligament is classified as a medial collateral ligament?

    <p>Tibial collateral ligament</p> Signup and view all the answers

    Which of the following joints perform all angular movements in two planes?

    <p>Condyloid joint</p> Signup and view all the answers

    What describes the function of the anterior and posterior cruciate ligaments?

    <p>Control the forward and backward movement of the knee</p> Signup and view all the answers

    What best describes a plane synovial joint?

    <p>Allows gliding movements between flat surfaces</p> Signup and view all the answers

    Which of the following statements about saddle joints is true?

    <p>They have both convex and concave surfaces.</p> Signup and view all the answers

    What characteristic describes the ability of muscles to return to their original shape after being stretched?

    <p>Elasticity</p> Signup and view all the answers

    Which type of muscle tissue is responsible for involuntary movements and is found in the heart?

    <p>Cardiac muscle</p> Signup and view all the answers

    What is the primary function of the skeletal muscles listed?

    <p>Stabilize joints and maintain posture</p> Signup and view all the answers

    Which of the following best represents the components of muscle fiber structure?

    <p>Single cell with multiple nuclei and sarcolemma</p> Signup and view all the answers

    What type of muscle attachment involves a tendon or aponeurosis?

    <p>Indirect attachment</p> Signup and view all the answers

    What protein covers the myosin binding sites on actin filaments?

    <p>Tropomyosin</p> Signup and view all the answers

    Which part of the sarcomere is exclusively made of myosin filaments?

    <p>H-zone</p> Signup and view all the answers

    What role does TnC play in the troponin complex?

    <p>Binds calcium ions</p> Signup and view all the answers

    Which protein is known for its elastic properties and runs through thick filaments?

    <p>Titin</p> Signup and view all the answers

    Which component is responsible for binding actin filaments to the Z-disc?

    <p>Actinin</p> Signup and view all the answers

    What is the primary role of dystrophin in muscle fibers?

    <p>Links cytoskeletal components to the extracellular matrix</p> Signup and view all the answers

    Which characteristic is associated with actin filaments?

    <p>Consist of monomers that polymerize into F-actin</p> Signup and view all the answers

    What is the primary functional unit of a myofibril?

    <p>Sarcomere</p> Signup and view all the answers

    What occurs at the neuromuscular junction to initiate muscle contraction?

    <p>Release of acetylcholine</p> Signup and view all the answers

    Which statement accurately describes a motor unit?

    <p>Consists of one motor neuron and all the muscle fibers it supplies</p> Signup and view all the answers

    During synaptic transmission, what triggers the release of neurotransmitter from axonal terminals?

    <p>Influx of calcium ions</p> Signup and view all the answers

    What role does calcium ions play in muscle contraction?

    <p>They bind to troponin to trigger myosin interactions</p> Signup and view all the answers

    What happens to the sarcomeres during muscle contraction according to the sliding filament theory?

    <p>They shorten and the I-band and H-zone become smaller</p> Signup and view all the answers

    What is a necessary requirement for the sliding filament mechanism to continue?

    <p>Presence of ATP and calcium ions</p> Signup and view all the answers

    What initiates the action potential at the neuromuscular junction?

    <p>Release of acetylcholine binding to receptors</p> Signup and view all the answers

    Which neural structure is responsible for transmitting signals to the muscle fibers?

    <p>Axon terminals</p> Signup and view all the answers

    What happens immediately after action potential spreads along the sarcolemma?

    <p>Calcium ions are released from the sarcoplasmic reticulum</p> Signup and view all the answers

    What is the primary cause of rigor mortis following death?

    <p>Lack of ATP</p> Signup and view all the answers

    Which type of muscle fiber is characterized by high fatigue resistance and slower contraction speed?

    <p>Slow Oxidative Fibers (Type I)</p> Signup and view all the answers

    What process primarily generates ATP for muscle activity during short-term intense exercise lasting 10 to 40 seconds?

    <p>Anaerobic glycolysis</p> Signup and view all the answers

    Which muscle fiber type is primarily used for activities like weightlifting and sprinting?

    <p>Fast Glycolytic Fibers (Type IIb)</p> Signup and view all the answers

    What is the role of Ca2+ in muscle contraction?

    <p>It stimulates myosin heads to form cross-bridges with actin</p> Signup and view all the answers

    What is the main source of ATP during the initial 10 seconds of muscle activity?

    <p>Creatine phosphate</p> Signup and view all the answers

    What happens to calcium ions after a muscle contraction has ended?

    <p>They are pumped back into the sarcoplasmic reticulum</p> Signup and view all the answers

    What characterizes the energy system during the Krebs cycle?

    <p>Complete aerobic oxidation of glucose</p> Signup and view all the answers

    Which type of muscle fiber has a high content of myoglobin and is less fatigable?

    <p>Slow Oxidative Fibers (Type I)</p> Signup and view all the answers

    What physiological change occurs 24-36 hours after death?

    <p>Muscles become flaccid</p> Signup and view all the answers

    What best describes the all-or-none phenomenon in muscle contractions?

    <p>Muscle fibers contract fully or not at all regardless of stimulus strength.</p> Signup and view all the answers

    During which phase of a muscle twitch does the muscle actually shorten and generate force?

    <p>Contraction phase</p> Signup and view all the answers

    What occurs during tetanus in muscle contractions?

    <p>Complete fusion of muscle twitches resulting in a smooth contraction.</p> Signup and view all the answers

    Which statement best describes isotonic muscle contractions?

    <p>The muscle tension remains constant while the muscle length changes.</p> Signup and view all the answers

    What distinguishes single-unit smooth muscle from multi-unit smooth muscle?

    <p>Single-unit smooth muscles contract together as a functional syncytium.</p> Signup and view all the answers

    Which of the following is a significant characteristic of smooth muscle contraction?

    <p>Calmodulin binds calcium to initiate contraction.</p> Signup and view all the answers

    What is the primary effect of fatigue on muscle contractions?

    <p>The muscle loses its ability to maintain a contraction.</p> Signup and view all the answers

    Which statement is correct regarding the role of extracellular calcium in smooth muscle contraction?

    <p>Extracellular calcium is essential for initiating smooth muscle contractions.</p> Signup and view all the answers

    What condition is characterized by weakness of the extrinsic eye muscles and facial expression muscles?

    <p>Myasthenia gravis</p> Signup and view all the answers

    What is the primary reason skeletal muscles are named?

    <p>Based on characteristics such as location and size</p> Signup and view all the answers

    Which muscle group is primarily involved in facial expressions?

    <p>Muscles of facial expression</p> Signup and view all the answers

    Which muscle is commonly known for its role in elevating the mandible for chewing?

    <p>Temporalis</p> Signup and view all the answers

    What function does the deltoid muscle serve?

    <p>Abducting the arm</p> Signup and view all the answers

    Which muscle is identified for its action in mastication?

    <p>Masseter</p> Signup and view all the answers

    Which muscle is primarily involved in moving the upper arm and shoulder?

    <p>Deltoid</p> Signup and view all the answers

    Which muscle does NOT belong to the group of trunk muscles moving the abdomen?

    <p>Pectoralis minor</p> Signup and view all the answers

    What action is primarily associated with the biceps brachii muscle?

    <p>Flexing the forearm</p> Signup and view all the answers

    Which of the following muscles helps in the process of respiration?

    <p>Diaphragm</p> Signup and view all the answers

    Which of the following is a deep anterior muscle that moves the thigh at the hip?

    <p>Iliopsoas</p> Signup and view all the answers

    Which muscle is primarily responsible for extending the knee?

    <p>Rectus femoris</p> Signup and view all the answers

    Which muscles are involved in the process of respiration?

    <p>External intercostals and Diaphragm</p> Signup and view all the answers

    Which muscle functions primarily to flex the wrist?

    <p>Flexor carpi ulnaris</p> Signup and view all the answers

    Which muscle group is categorized as the hamstrings?

    <p>Biceps femoris, Semitendinosus, Semimembranosus</p> Signup and view all the answers

    Which muscle is part of the quadriceps femoris group?

    <p>Vastus lateralis</p> Signup and view all the answers

    Which muscle can be identified as an antagonist to the flexor carpi ulnaris?

    <p>Extensor carpi radialis</p> Signup and view all the answers

    Which muscle plays a significant role in hip flexion?

    <p>Iliopsoas</p> Signup and view all the answers

    Which of the following muscles is NOT part of the trunk muscles that move the abdomen?

    <p>Triceps brachii</p> Signup and view all the answers

    Which muscle group is primarily responsible for plantar flexion of the ankle?

    <p>Gastrocnemius</p> Signup and view all the answers

    Which muscle primarily aids in the flexion of the digits?

    <p>Flexor digitorum superficiales</p> Signup and view all the answers

    Which type of neuron is primarily responsible for transmitting sensory information to the central nervous system?

    <p>Afferent neurons</p> Signup and view all the answers

    What is the primary function of oligodendrocytes in the nervous system?

    <p>Myelinating CNS axons</p> Signup and view all the answers

    What best describes the composition of nervous tissue?

    <p>Highly cellular with only 20% extracellular space</p> Signup and view all the answers

    What structure in neurons primarily functions as the receptive or input region?

    <p>Dendrites</p> Signup and view all the answers

    Which type of supporting cell is found in the peripheral nervous system?

    <p>Schwann cells</p> Signup and view all the answers

    Which of the following neuron types does NOT originate from bipolar cells during embryonic development?

    <p>Multipolar neurons</p> Signup and view all the answers

    Which structure in the nervous system is primarily responsible for the secretory output of a neuron?

    <p>Axonal endings</p> Signup and view all the answers

    What do the terms 'ganglion' and 'tract' refer to in nervous system terminology?

    <p>Ganglia are clusters of neuron cell bodies; tracts are bundles of axons</p> Signup and view all the answers

    Which component of the neuron is primarily responsible for conducting impulses away from the cell body?

    <p>Axon</p> Signup and view all the answers

    Which type of neuron is primarily involved in reflex actions and connects sensory and motor neurons?

    <p>Interneurons</p> Signup and view all the answers

    What is the typical resting membrane potential of most neurons?

    <p>-40 to -90 mV</p> Signup and view all the answers

    Which type of channel is responsible for the generation of action potentials?

    <p>Voltage-gated channels</p> Signup and view all the answers

    What phenomenon describes the self-propagating nature of action potentials along the axon?

    <p>Saltatory propagation</p> Signup and view all the answers

    What role does the Na+-K+ pump play in neurons?

    <p>It maintains resting membrane potential by moving ions.</p> Signup and view all the answers

    What is the correct term for the brief reversal of polarity during an action potential?

    <p>Depolarization</p> Signup and view all the answers

    What characterizes the absolute refractory period of an action potential?

    <p>There is no response to any stimulus.</p> Signup and view all the answers

    Which type of potential is associated with sensory receptor stimuli?

    <p>Receptor potential</p> Signup and view all the answers

    What term describes the difference in ion concentrations between the extracellular fluid and intracellular fluid in neurons?

    <p>Electrochemical gradient</p> Signup and view all the answers

    What do chemically-gated channels respond to in the context of neuronal function?

    <p>The binding of specific neurotransmitters</p> Signup and view all the answers

    Which statement is true regarding graded potentials?

    <p>They can vary in size and duration.</p> Signup and view all the answers

    Which type of joint allows for the greatest range of motion?

    <p>Ball-and-socket joint</p> Signup and view all the answers

    What effect does parathyroid hormone have on bone density?

    <p>It decreases bone density.</p> Signup and view all the answers

    Which cells are primarily responsible for bone resorption?

    <p>Osteoclasts</p> Signup and view all the answers

    What defines the function of synovial fluid in joints?

    <p>It reduces friction during movement.</p> Signup and view all the answers

    Which of the following types of muscles is involuntary?

    <p>Both B and C</p> Signup and view all the answers

    What is the primary function of the cervical vertebrae?

    <p>Support the skull</p> Signup and view all the answers

    Which hormone has been shown to promote the deposition of bone tissue?

    <p>Calcitonin</p> Signup and view all the answers

    In which type of joint would you find articular cartilage?

    <p>Synovial joint</p> Signup and view all the answers

    Which of the following best describes osteomalacia?

    <p>Softening of bones due to vitamin D deficiency</p> Signup and view all the answers

    What is the role of tendons in muscle anatomy?

    <p>Connect muscles to bones</p> Signup and view all the answers

    What is the primary role of calcium ions in muscle contraction?

    <p>To bind with tropomyosin and expose actin sites</p> Signup and view all the answers

    Which type of muscle fibers is primarily responsible for endurance activities?

    <p>Red muscle fibers</p> Signup and view all the answers

    In the context of muscle contractions, what distinguishes isometric from isotonic contractions?

    <p>Isometric contractions maintain muscle length, while isotonic change length</p> Signup and view all the answers

    Which muscle is primarily involved in the process of breathing?

    <p>Diaphragm</p> Signup and view all the answers

    What effect does rigor mortis have on muscle tissue after death?

    <p>It prevents the sliding filament mechanism from occurring</p> Signup and view all the answers

    Which muscle in the head is responsible for closing the eyelids?

    <p>Orbicularis oculi</p> Signup and view all the answers

    What is the primary function of dystrophin in muscle cells?

    <p>Connects muscle fibers to the extracellular matrix</p> Signup and view all the answers

    Which muscle is part of the quadriceps femoris group?

    <p>Vastus lateralis</p> Signup and view all the answers

    Myasthenia gravis is characterized by which primary issue?

    <p>Autoimmune attack on neuromuscular junctions</p> Signup and view all the answers

    What distinguishes smooth muscle from skeletal muscle?

    <p>Smooth muscle is non-striated and involuntary</p> Signup and view all the answers

    Which organ is NOT part of the nervous system?

    <p>Liver</p> Signup and view all the answers

    What is the primary function of supporting cells in the CNS?

    <p>Providing structural support</p> Signup and view all the answers

    Which type of neuron is primarily responsible for transmitting sensory information to the central nervous system?

    <p>Afferent neurons</p> Signup and view all the answers

    Which cell type is exclusive to the peripheral nervous system (PNS)?

    <p>Schwann cells</p> Signup and view all the answers

    What characteristic is NOT associated with neurons?

    <p>Regeneration of axons</p> Signup and view all the answers

    Which component of a neuron is primarily responsible for conducting electrical signals?

    <p>Axon</p> Signup and view all the answers

    In the structure of neurons, what does the term 'perikaryon' refer to?

    <p>Cell body of the neuron</p> Signup and view all the answers

    What type of neuron originates embryologically as a bipolar cell?

    <p>Unipolar neurons</p> Signup and view all the answers

    Which type of neuron is characterized by its role in connecting sensory and motor neurons?

    <p>Interneurons</p> Signup and view all the answers

    What is the primary function of dendrites in a neuron?

    <p>Receive signals from other neurons</p> Signup and view all the answers

    What primarily determines the resting membrane potential of most neurons?

    <p>Charge of non-diffusible molecules in the cytoplasm</p> Signup and view all the answers

    Which ion movement is primarily associated with depolarization during an action potential?

    <p>Na+ moving into the cell</p> Signup and view all the answers

    Which statement about action potential propagation is accurate?

    <p>It occurs in a self-propagating manner.</p> Signup and view all the answers

    What characterizes the refractory period during action potential generation?

    <p>Increased threshold for a subsequent action potential</p> Signup and view all the answers

    What type of potential is generated when a receptor responds to a stimulus?

    <p>Graded potential</p> Signup and view all the answers

    Which of the following types of channels is NOT correctly paired with its function?

    <p>Passive channel - requires ATP to function</p> Signup and view all the answers

    What role does the Na+-K+ pump play in neuron function?

    <p>It establishes resting membrane potential by maintaining ionic gradients.</p> Signup and view all the answers

    Which statement about synapses is true?

    <p>Neurons can have thousands of axonal terminals forming synapses.</p> Signup and view all the answers

    What phenomenon describes the behavior of action potentials once a threshold is achieved?

    <p>All-or-None phenomenon</p> Signup and view all the answers

    Which of the following does NOT describe saltatory propagation of action potentials?

    <p>It leads to a decreased speed of conduction.</p> Signup and view all the answers

    Study Notes

    Bones and Skeletal Tissues

    • Bone: Hard, dense connective tissue that makes up the skeleton
      • Compact bone: Dense and strong, found in the diaphysis (shaft) of long bones
      • Spongy bone: Lighter and less dense, found in the epiphyses (ends) of long bones and in flat bones
    • Cartilage: Flexible connective tissue that provides support and cushioning
      • Types of cartilage:
        • Hyaline cartilage: Most abundant, found in costal cartilages, laryngeal cartilage, tracheal and bronchial cartilages, nasal cartilages, articular cartilages (joints)
        • Elastic cartilage: Found in ear pinna and epiglottis, contains elastin fibers for flexibility
        • Fibrocartilage: Found in intervertebral discs and pubic symphysis, resists high pressures and contains lots of collagen

    Bone Functions

    • Support: Provides framework for the body
    • Protection: Protects vital organs
    • Movement: Provides attachment points for muscles
    • Mineral storage: Stores calcium and phosphorus
    • Hematopoiesis: Production of blood cells in the bone marrow

    Cartilage Structure

    • Composition: 80% water, compressible, no blood vessels or nerves
    • Covered by perichondrium: A dense connective tissue membrane
    • Cells:
      • Chondroblasts: Immature cartilage cells that produce matrix
      • Chondrocytes: Mature cartilage cells located in lacunae (cavities)
    • Extracellular matrix: Contains:
      • Glucoseaminoglycans (GAGs): Chondroitin sulfate and hyaluronic acid
      • Collagen and elastin fibers: Provide strength and flexibility

    Cartilage Growth

    • Appositional growth: Growth from the outside in, new matrix deposited by chondroblasts in perichondrium
    • Interstitial growth: Growth from the inside out, chondrocytes divide and secrete new matrix

    Bone Classification

    • Small bones: Sesamoid bones (e.g., patella)
    • Long bones: Longer than they are wide (e.g., femur, humerus)
    • Large bones: Large and irregular in shape (e.g., pelvis)
    • Flat bones: Thin and flattened (e.g., skull bones, ribs)
    • Short bones: Cube-shaped (e.g., carpals, tarsals)
    • Irregular bones: Complex shapes (e.g., vertebrae)
    • Wormian bones: Small, irregular bones found in sutures of the skull
    • Sesamoid bones: Small, round bones embedded in tendons (e.g., patella)
    • Diploe: Spongy bone layer found in flat bones

    Compact Bone Structure

    • Osteon: Basic structural unit of compact bone, also known as Haversian system
      • Central canal: Contains blood vessels and nerves
      • Concentric lamellae: Rings of bone tissue surrounding the central canal
      • Osteocytes: Mature bone cells located in lacunae
      • Lacunae: Small cavities that house osteocytes
      • Canaliculi: Tiny canals that connect lacunae and allow for nutrient and waste exchange
      • Perforating canals (Volkmann's canals): Connect central canals of adjacent osteons
      • Interstitial lamellae: Remnants of old osteons
      • Circumferential lamellae: Outermost layer of compact bone

    Spongy Bone Structure

    • Trabeculae: Irregularly arranged lamellae and osteocytes
    • Few cells in thickness: No osteons are present
    • Osteocytes: Located in lacunae and interconnected by canaliculi

    Bone Development

    • Osteogenesis or ossification: Process of bone formation
      • Intramembranous ossification: Formation of bone directly from mesenchymal tissue
        • Begins around 8th week of development
        • Mesenchymal cells differentiate into osteoblasts
        • Primary ossification centers form
        • Osteoblasts secrete osteoid (bone matrix) and minerals
        • Bony plates (diploe) form
        • Fontanelles (soft spots) are present in infants
        • Sutures (joints between skull bones) form
      • Endochondral ossification: Formation of bone from hyaline cartilage
        • Begins around 8 weeks of development
        • Perichondrium becomes vascularized
        • Cartilage is replaced by bone
        • Primary ossification center forms in the diaphysis of cartilage
        • Bone collar, shaft, and medullary cavity develop
        • Secondary ossification centers form at the ends of the bone (epiphysis)
        • Epiphyseal plate (growth plate) is responsible for longitudinal bone growth
      • Role of epiphyseal plate in bone elongation:
        • New cartilage forms first, then is converted into bone
        • Zones of proliferation, hypertrophy, calcification, and ossification
        • Epiphyseal line forms when growth stops

    Bone Growth in Width

    • Bone resorption: Osteoclasts in endosteum break down bone tissue
    • Bone formation: Osteoblasts in periosteum deposit new bone tissue
    • Medullary cavity widens: As bone resorption outpaces bone formation on the inside

    Bones and Hormones

    • Parathyroid hormone (PTH): Increases blood calcium levels
    • Calcitonin: Decreases blood calcium levels
    • Growth hormone: Stimulates bone growth
    • Thyroid hormones: Promote bone growth
    • Estrogens: Promote bone growth and density
    • Vitamin D3: Essential for calcium absorption

    Bone Diseases

    • Osteoporosis: Decreased bone density, leading to increased risk of fractures
    • Osteopenia: Reduced bone density, not as severe as osteoporosis
    • Osteomalacia: Softening of bones due to inadequate mineralization

    Bone Fractures

    • Colle's fracture: Fracture of the distal radius, usually caused by a fall onto an outstretched hand
    • Pott's fracture: Fracture of the distal fibula, usually caused by an inversion injury of the foot
    • Greenstick fracture: Incomplete fracture, common in children
    • Comminuted fracture: Bone is broken into multiple pieces
    • Compression fracture: Collapse of a bone due to compression, usually occurs in vertebrae

    Bone Markings

    • Tuberosity: Large rounded projection
    • Crest: Narrow ridge
    • Trochanter: Very large, blunt, irregular projection
    • Line: Narrow line, less prominent than a crest
    • Tubercle: Small rounded projection
    • Epicondyle: Raised area above a condyle
    • Spine: Sharp projection (e.g., vertebrae)
    • Head: Rounded articular surface, often found at the end of a bone
    • Facet: Smooth, flat articular surface
    • Condyle: Rounded articular surface or projection
    • Ramus: Arm-like bar of bone
    • Meatus: Canal-like passageway
    • Sinus: Air-filled cavity within a bone, lined with mucous membrane
    • Fossa: Shallow, basin-like depression for articulation
    • Groove: Furrow
    • Fissure: Narrow, slit-like opening
    • Foramen: Round or oval opening

    Joints

    • Sites where two or more bones meet
    • Classified by structure and function

    Structural Classification

    • Fibrous: Bones connected by fibrous connective tissue
      • Sutures: Found between skull bones
      • Syndesmoses: Connected by ligaments or sheets of fibrous tissue
      • Gomphoses: Periodontal ligaments connect teeth to sockets
    • Cartilaginous: Bones united by cartilage
      • Synchondroses: Hyaline cartilage connects bones
      • Symphysis: Fibrocartilage connects bones

    Functional Classification

    • Synarthroses: Immovable joints
    • Amphiarthroses: Slightly movable joints
    • Diarthroses: Freely movable joints

    Fibrous Joints

    • Mostly synarthrotic, meaning immovable

    • Lack a joint cavity

    • Three types:

      • Sutures: Immovable joints found only in the skull
      • Syndesmoses: Slightly movable joints (distal ends of tibia and fibula, radius and ulna)
      • Gomphoses: Periodontal ligaments connect teeth to bone sockets.

    Cartilaginous Joints

    • Lack a joint cavity

    • Two types:

      • Synchondroses: Hyaline cartilage unites bones, allowing for bone growth during youth. Later ossify and become immovable.
      • Symphysis: Fibrocartilage connects bones, providing shock absorption.

    Synovial Joints

    • Freely movable joints
    • Consist of:
      • Hyaline cartilage covering opposing bone surfaces
      • Articular cavity filled with synovial fluid
      • Joint capsule enclosing the articular cavity (outer fibrous layer, inner synovial membrane)
      • Reinforcing ligaments for joint strength
        • Intrinsic or capsular ligaments (thickened fibrous capsule)
        • Extracapsular ligaments (outside the capsule)
        • Intracapsular ligaments (covered by synovial membrane, not within the synovial cavity)
      • Fat pads for cushioning
      • Articular discs or menisci:
        • Wedges of fibrocartilage found in knees and jaws
        • Divide synovial cavity for better fit and joint stability

    Bursae and Tendon Sheaths

    • Bursa: Flattened sacs filled with lubricant, found near joints
    • Tendon sheath: Similar to bursa, but encases tendons

    Types of Synovial Joints

    • Plane: Allows gliding movement (e.g., between carpals)
    • Hinge: Uniaxial, allows flexion and extension (e.g., elbow, interphalangeal joints)
    • Pivot: Uniaxial, allows rotation (e.g., between atlas and axis, proximal radio-ulnar joint)
    • Condyloid: Biaxial, allows all angular movements (e.g., radius-carpal, metacarpo-phalangeal joints)
    • Saddle: Allows greater freedom than condyloid, both surfaces have convex and concave areas (e.g., carpo-metacarpal joint of thumb)
    • Ball-and-Socket: Multiaxial, allows most free movement (e.g., shoulder, hip joints)

    Movements Allowed by Synovial Joints

    • Gliding: Nonaxial movement, involves slipping of surfaces
    • Angular: Movement around an axis:
      • Flexion: Decreases the angle between bones
      • Extension: Increases the angle between bones
      • Hyperextension: Increases the angle beyond anatomical position
      • Abduction: Movement away from the midline
      • Adduction: Movement towards the midline
      • Circumduction: Combination of flexion, extension, abduction, and adduction
    • Rotation: Movement around a bone's own axis
    • Special movements:
      • Supination: Palm facing forward
      • Pronation: Palm facing backward
      • Inversion: Sole of foot inward
      • Eversion: Sole of foot outward
      • Protraction: Movement forward
      • Retraction: Movement backward
      • Elevation: Movement upward
      • Depression: Movement downward
      • Opposition: Thumb touching other fingers

    Joint Injuries

    • Sprain: Forcible twisting of a joint, stretching or tearing ligaments without bone dislocation

    Inflammatory and Degenerative Disorders

    • Bursitis: Inflammation of a bursa
      • Tendonitis: Inflammation of a tendon

    Arthritis

    • Rheumatoid Arthritis (RA): Autoimmune disease causing inflammation of synovial membrane, leading to joint stiffness, pain, and loss of function. - Affects people between 40-50 years old. - Aspirin and antibiotics can help manage symptoms.
    • Osteoarthritis (OA): Degenerative joint disease, "wear-and-tear" arthritis.
      • Deterioration of articular cartilage and bone spur formation occurs, leading to pain and loss of function.
      • Primarily affects weight-bearing joints and lumbar spine.
      • Non-inflammatory.

    Sarcomere Structure

    • Muscle fibers are made of hundreds of cylindrical myofibrils.
    • Myofibrils are made of protein filaments called myofilaments.
    • Thin myofilaments are made of actin and are anchored to Z-discs.
    • Thick myofilaments are made of myosin and are arranged tail-to-tail.
    • Myofibrils are made of repeating contractile units called sarcomeres.
    • Sarcomeres are composed of distinct bands: I-band, A-band, Z-disc, H-zone, and M-line.

    Muscle Proteins

    • Tropomyosin covers myosin binding sites on actin filaments.
    • Troponin is a complex of three proteins: TnT, TnC, and TnI which are critical for muscle contraction.
      • TnT binds to tropomyosin, forming a troponin-tropomyosin complex.
      • TnC binds calcium ions.
      • TnI binds to actin filaments, holding the actin-tropomyosin complex in place and blocking myosin binding sites.
    • Titin is a large elastic protein that runs through thick filaments.
    • Actinin is a non-elastic protein that anchors actin filaments to the Z-disc and cross-links thin filaments in neighboring sarcomeres to allow for coordinated contraction.
    • Dystrophin connects the muscle cytoskeletal elements to the extracellular matrix and is involved in Duchenne Muscular Dystrophy.
    • Myosin binding protein C helps limit the number of cross-bridges that can form in the heart.

    Actin Filaments

    • Thin filaments
    • Actin monomers polymerize forming two twisted strands of F-actin.
    • Each filament consists of 300-400 actin molecules.
    • Actinin binds actin filaments to the Z-line.

    Tropomyosin

    • Associated with actin filaments
    • Fills the groove between F-actin strands, providing stiffness.

    Troponin

    • Associated with tropomyosin and composed of three subunits: TnI, TnT, and TnC.

    Neuromuscular Junction

    • Myoneural junction is the connection between a motor neuron and a muscle fiber.
    • Axons of motor neurons branch into axonal terminals.
    • Each muscle fiber receives input from only one axonal terminal, forming a neuromuscular junction.
    • A motor unit consists of a single motor neuron and all the muscle fibers it innervates.
    • Small motor units are found in muscles requiring fine control, such as eye muscles and muscles in the hand.
    • Large motor units are found in muscles requiring less precision, such as leg muscles.

    Synaptic Transmission at Neuromuscular Junction

    • An action potential travels down the motor neuron to the axonal terminal.
    • This triggers the opening of voltage-gated calcium channels.
    • Calcium influx causes the release of acetylcholine (ACh) from synaptic vesicles.
    • ACh diffuses across the synaptic cleft and binds to ACh receptors on the muscle fiber's sarcolemma.
    • This binding opens sodium channels, allowing sodium ions to enter the muscle fiber, generating an action potential.
    • The muscle action potential travels along the sarcolemma and into T-tubules.
    • This triggers the release of calcium from the sarcoplasmic reticulum (SR).
    • Calcium ions bind to troponin C, causing a conformational change and exposing myosin binding sites on actin.
    • Energized myosin heads bind to actin, forming cross-bridges.
    • Acetylcholinesterase degrades ACh, terminating the signal.

    Skeletal Muscle Physiology: Sliding Filament Theory

    • Excitation-contraction coupling describes the process by which a stimulus triggers muscle contraction.
    • Stimulus arrives at the neuromuscular junction.
    • Action potential travels along the sarcolemma and T-tubules.
    • Calcium ions are released from the SR.
    • ATP powers the formation of myosin-actin cross-bridges, causing the filaments to slide past each other.
    • Sliding continues as long as calcium and ATP are present.
    • Sarcomeres shorten, I-band and H-zone decrease due to filament overlap.
    • Connective tissue layers (epimysium, perimysium, endomysium) pull on the tendons, which in turn move the bone.

    Muscle Relaxation

    • Stimulus to the motor end plate ceases.
    • Calcium ions are pumped back into the SR by an ATP-dependent Ca pump.
    • Acetylcholinesterase degrades remaining ACh.
    • Myosin heads detach from actin.
    • Sarcomeres return to their resting length.

    Rigor Mortis

    • Occurs 6-24 hours after death due to lack of ATP.
    • Calcium ions remain bound to troponin, keeping myosin heads bound to actin, creating a stiff muscle.
    • Muscles become flaccid 24-36 hours after death due to the breakdown of muscle proteins by lysosomal enzymes.

    Energy Demands of Muscles

    • Short-term activity is powered by ATP already present in the muscle (10 seconds), myokinase, and creatine phosphate.
    • Glycolysis provides energy for 10-40 seconds through anaerobic oxidation of glucose, producing 2 ATP and 2 NADH2.
    • Muscle glycogen is broken down, leading to lactic acid accumulation and muscle fatigue.
    • Krebs cycle provides a significant amount of ATP through the complete aerobic oxidation of glucose during extended work. This requires a constant supply of oxygen.

    Types of Muscle Fibers

    • Slow Oxidative Fibers (Type I): Red, contain myoglobin, thin, aerobic fibers.
      • Generate less force, are non-fatigable, contain slow-acting ATPase in the myosin head.
      • Found in postural muscles.
    • Fast Oxidative Fibers (Type IIa): Pink, contain some myoglobin, thicker fibers.
      • Generate medium force, less fatigable, contain fast-acting ATPase in the myosin head.
      • Involved in light work and walking.
    • Fast Glycolytic Fibers (Type IIb): White, lack myoglobin, thick, glycolytic fibers.
      • Generate a lot of force, easily fatigued, contain fast-acting ATPase in the myosin head.
      • Used in weightlifting and sprinting.

    Graded Muscle Contractions

    • Muscles exhibit a graded contraction, meaning they can generate varying levels of force.
    • Muscle twitch is the response to a single threshold stimulus and has three phases: latent phase, contraction phase, and relaxation phase.
    • Summation: increased frequency of stimulus leads to increased force, with twitches fusing together.
    • Tetanus: continuous smooth contraction due to very high stimulus frequency.
    • Fatigue: muscle loses its ability to maintain contraction due to prolonged stimulation.

    Isotonic and Isometric Muscle Contractions

    • Isotonic contraction: muscle length changes while tension remains constant.
    • Isometric contraction: muscle tension increases while length remains constant.
    • Most muscle contractions are a combination of both isotonic and isometric contractions.

    Myasthenia Gravis

    • An autoimmune disease that affects ACh receptors, leading to muscle weakness.
    • Primarily affects muscles of the eyes, eyelids, facial expression, chewing, talking, and swallowing.

    Smooth Muscles

    • Found in various organs like the GI tract, blood vessels, urinary bladder, uterus, urethra, and ureter.
    • Individual cells are nucleated and contain irregularly arranged sarcomeres.
    • Contract in three dimensions.
    • Lack a SR and rely on extracellular calcium stored in caveolae for contraction.
    • Dense bodies serve as anchor points for thin filaments (similar to Z-discs).
    • Do not contain troponin.
    • Calmodulin, a calcium-binding protein, activates MLCK (myosin light-chain kinase), leading to cross-bridge formation.
    • Respond to hormones like oxytocin and epinephrine, as well as acetylcholine.
    • Can remain extended without fatigue.
    • Two types of smooth muscle: single-unit (smooth muscle cells contract together) and multi-unit (smooth muscle cells contract independently).

    Skeletal Muscles

    • Responsible for voluntary movement.
    • Striated appearance due to the arrangement of sarcomeres.
    • Muscles contain nerves, blood vessels, and connective tissue.
    • Muscles are attached to bones via tendons or aponeuroses and have an origin (usually on a relatively stationary bone) and insertion (usually on a movable bone).

    Cardiac Muscles

    • Found only in the heart.
    • Like skeletal muscles, cardiac muscles are striated, but they are branched and interconnected by intercalated discs.
    • Cardiac muscle contractions are involuntary and rhythmic.

    Smooth Muscles

    • Found in walls of internal organs.
    • Non-striated, involuntary, and generally slower contracting than skeletal muscles.

    Functional Characteristics of Muscle Tissue

    • Excitability or irritability: ability to respond to a stimulus.
    • Conductivity: ability to transmit impulses.
    • Contractility: ability to shorten.
    • Extensibility: ability to stretch.
    • Elasticity: ability to return to original length after stretching.

    Functions of Muscle Tissue

    • Produce physical movement.
    • Maintain posture.
    • Stabilize joints.
    • Generate heat.

    Skeletal Muscle Anatomy

    • Each skeletal muscle is composed of muscle fibers, nerves, blood vessels, and connective tissue.
    • Origin: usually the more stationary attachment point.
    • Insertion: usually the more movable attachment point.
    • Attachments:
      • Direct attachment: muscle epimysium fuses directly to the periosteum of bone or perichondrium of cartilage.
      • Indirect attachment: muscle epimysium extends as a tendon or aponeurosis to attach to bone or cartilage.
      • Attachment to fascia: muscle may attach to the fascia of other muscles via a fibrous raphe (e.g., linea alba).

    Skeletal Muscle Fiber Structure

    • Each muscle fiber is a single cell.
    • Muscle fibers are unbranched, cylindrical, multinucleate, and contain mitochondria.
    • The plasma membrane of a muscle fiber is called the sarcolemma.
    • Connective Tissue Layers:
      • Endomysium: areolar connective tissue surrounding individual muscle fibers.
      • Perimysium: fibrous connective tissue surrounding bundles of muscle fibers called fascicles.
      • Epimysium: dense fibrous connective tissue surrounding the entire muscle.
      • Deep fascia: fibrous connective tissue that forms tendons, ligaments, and other structures.
      • Superficial fascia (hypodermis): subcutaneous layer.

    Summary

    This summary covered the structure and function of muscle tissue, including the three main types: skeletal, cardiac, and smooth muscle. It delved into the structure of a sarcomere, the proteins involved in muscle contraction, the neuromuscular junction, the sliding filament theory, energy demands, and the various types of muscle fibers. Additionally, it discussed the different types of muscle contractions and certain diseases related to muscle function, like Myasthenia Gravis. This information provides a comprehensive understanding of the intricate workings of muscle tissue and its vital roles in the human body.

    Muscular System Overview

    • Human body contains over 600 skeletal muscles
    • Muscles named based on characteristics: location, size, shape, fiber direction, number of origins, action, origin and insertion

    Muscle Grouping

    • Muscles grouped based on location and function
      • Facial expression
      • Mastication
      • Head movement
      • Swallowing
      • Respiration
      • Abdomen movement
      • Vertebral column movement
      • Upper arm and shoulder movement (anterior and posterior)
      • Forearm movement at elbow
      • Hand and digit movement (anterior and posterior)
      • Thigh movement at hip and/or knee (anterior/medial and posterior)
      • Ankle and digit movement (anterior/lateral and posterior)

    Selected Skeletal Muscles

    Head and Neck

    • Epicranius (aka occipito-frontalis)
    • Orbicularis oculi
    • Orbicularis oris
    • Zygomaticus major and minor
    • Mentalis
    • Platysma
    • Masseter *
    • Temporalis
    • Buccinator
    • Sternocleidomastoid
    • Digastric
    • Stylohyoid

    Anterior Trunk Muscles (arm and shoulder movement)

    • Pectoralis major
    • Deltoid *
    • Serratus anterior
    • Pectoralis minor
    • Biceps brachii *
    • Brachioradialis *

    Posterior Trunk Muscles (arm and shoulder movement)

    • Trapezius
    • Latissimus dorsi
    • Triceps brachii *
    • Infraspinatus
    • Teres major
    • Rhomboids

    Wrist and Hand Movement

    • Flexor carpi ulnaris *
    • Flexor digitorum superficiales *
    • Extensor digitorum *
    • Extensor carpi ulnaris *

    Abdomen Movement

    • Rectus abdominis
    • External oblique
    • Internal oblique
    • Transversus abdominis

    Respiration

    • External intercostals
    • Internal intercostals *
    • Diaphragm *

    Anterior Leg Muscles (hip and/or knee movement)

    • Iliopsoas
    • Sartorius
    • Gracilis
    • Adductor longus
      • Quadriceps femoris
        • Rectus femoris *
        • Vastus lateralis *
        • Vastus medialis *
        • Vastus intermedius *

    Posterior Leg Muscles (hip and/or knee movement)

    • Gluteus maximus
      • Hamstrings
        • Biceps femoris *
        • Semitendinosus *
        • Semimembranosus *

    Ankle and Foot Movement

    • Tibialis anterior *
    • Extensor digitorum longus *
    • Flexor digitorum longus *
    • Gastrocnemius *
    • Soleus

    Bone Functions

    • Support and shape the body
    • Protect vital organs, e.g., the skull protects the brain
    • Allow movement through attachment to muscles
    • Store minerals, primarily calcium and phosphorus
    • Produce blood cells in bone marrow

    Cartilage Structure and Types

    • Specialized connective tissue, avascular, contains chondrocytes in lacunae
    • Hyaline cartilage: smooth, glassy-appearing matrix, found in articular surfaces, nose, trachea, and ribs
    • Elastic cartilage: more flexible than hyaline cartilage due to elastic fibers, found in ears and epiglottis
    • Fibrocartilage: very strong, high tensile strength due to collagen fibers, found in intervertebral discs and menisci

    Bone Types

    • Compact bone: dense, solid outer layer, provides strength and support
    • Spongy bone: porous, inner layer, contains marrow, adds some strength but mainly supports and reduces bone weight.

    Classification of Bones

    • Long: longer than wide, e.g., femur, humerus
    • Short: cube-shaped, e.g., carpals, tarsals
    • Flat: thin, flattened, usually curved, e.g., skull bones, ribs, scapula
    • Irregular: complex shape, e.g., vertebrae, facial bones

    Structure of a Long Bone

    • Diaphysis: shaft of the bone
    • Epiphysis: ends of the bone, covered with articular cartilage
    • Periosteum: tough, fibrous membrane that covers the outer surface of the bone
    • Endosteum: thin membrane that lines the medullary cavity
    • Medullary cavity: hollow space within the diaphysis, filled with bone marrow

    Bone Microscopic Structure

    • Osteocytes: mature bone cells, housed in lacunae
    • Lacunae: small spaces within the matrix
    • Lamellae: concentric rings of matrix
    • Canaliculi: tiny canals that connect lacunae to each other and the central canal
    • Central canal (Haversian canal): houses blood vessels and nerves

    Bone Development

    • Intramembranous ossification: bone forms directly from mesenchymal tissue, occurs in flat bones
    • Endochondral ossification: bone forms from a cartilage model, occurs in long bones

    Bone Growth

    • Longitudinal growth: lengthens bone, occurs at the epiphyseal plate
    • Appositional growth: thickness growth of bone, occurs throughout life

    Bone Remodeling

    • Continuous process of bone breakdown and formation
    • Regulates bone density, mineral homeostasis, and repairs fractures
    • Mediated by osteoblasts (bone building) and osteoclasts (bone resorption)

    Bone Resorption

    • Removal of bone matrix by osteoclasts
    • Important for calcium homeostasis, bone remodeling, and fracture repair

    Axial Skeleton

    • Forms the central axis of the body
    • Includes skull, vertebral column, ribs, and sternum

    Skull

    • Cranium (8 bones): frontal, parietal (2), temporal (2), occipital, sphenoid, ethmoid
    • Facial bones (14 bones): maxillae (2), palatine (2), zygomatic (2), nasal (2), lacrimal (2), inferior nasal conchae (2), vomer, mandible

    Vertebral Column

    • 26 vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 1 sacrum, 1 coccyx

    Appendicular Skeleton

    • Bones of the limbs and their attachments to the axial skeleton
    • Includes pectoral girdle, upper limbs, pelvic girdle, and lower limbs

    Pectoral Girdle (Shoulder)

    • Connects upper limbs to axial skeleton
    • Consists of two clavicles and two scapulae

    Upper Limbs

    • Arm: humerus
    • Forearm: ulna and radius
    • Hand: carpals (wrist bones), metacarpals (palm bones), phalanges (finger bones)

    Pelvic Girdle (Hip)

    • Connects lower limbs to axial skeleton
    • Consists of two coxal bones (ilium, ischium, pubis)

    Lower Limbs

    • Thigh: femur
    • Lower leg: tibia and fibula
    • Foot: tarsals (ankle bones), metatarsals (foot bones), phalanges (toe bones)

    Functional Classification of Joints

    • Synarthroses: immovable joints
    • Amphiarthroses: slightly movable joints
    • Diarthroses: freely movable joints

    Structural Classification of Joints

    • Fibrous joints: connected by fibrous connective tissue
    • Sutures: found only between bones of the skull
    • Syndesmoses: bones connected by ligaments
    • Gomphoses: peg-and-socket joints, e.g., teeth in sockets
    • Cartilaginous joints: connected by cartilage
    • Synchondroses: hyaline cartilages unite bones
    • Symphyses: fibrocartilage unites bones
    • Synovial joints: enclosed by articular capsule, contains synovial fluid

    Synovial Fluid

    • Lubricates joint surfaces
    • Reduces friction between bones during movement
    • Provides nutrients to articular cartilage

    Classification of Diarthroses (Synovial) Joints

    • Uniaxial: movement in one plane
    • Plane: gliding movements
    • Hinge: flexion and extension
    • Pivot: rotation
    • Biaxial: movement in two planes
    • Condyloid: flexion/extension, abduction/adduction
    • Saddle: flexion/extension, abduction/adduction, circumduction
    • Multiaxial: movement in multiple planes
    • Ball-and-socket: flexion/extension, abduction/adduction, circumduction, rotation

    Special Movements

    • Gliding: sliding movements
    • Angular: increase or decrease angle between bones
    • Flexion: decrease angle
    • Extension: increase angle
    • Dorsiflexion: flexing foot upwards
    • Plantar flexion: pointing toes downwards
    • Abduction: movement away from midline
    • Adduction: movement towards midline
    • Circumduction: circular movement
    • Rotation: turning around a central axis
    • Supination: palm facing up
    • Pronation: palm facing down
    • Inversion: turning sole of foot inwards
    • Eversion: turning sole of foot outwards
    • Protraction: movement forward
    • Retraction: movement backward
    • Elevation: lifting body part up
    • Depression: lowering body part down
    • Opposition: touching thumb to fingertips

    Muscle Tissue

    • Skeletal muscle: voluntary, striated, responsible for movement
    • Cardiac muscle: involuntary, striated, found only in the heart
    • Smooth muscle: involuntary, non-striated, found in walls of internal organs

    Nervous System Organs

    • Composed of the brain, spinal cord, cranial nerves, spinal nerves, sympathetic nervous system and parasympathetic nervous system
    • Functions to receive sensory input and generate motor output

    Nervous Tissue

    • Highly cellular with densely packed cells
    • Contains neurons and supporting cells
    • Only about 20% of the tissue is extracellular space
    • Cells originate from ectodermal tissue, except microglia

    Supporting Cells of the Central Nervous System

    • Astrocytes: Help regulate the chemical environment of neurons and provide structural support
    • Microglial cells: Modified macrophages that phagocytize cellular debris and microorganisms
    • Ependymal cells: Line the cavities of the brain and spinal cord and produce cerebrospinal fluid
    • Oligodendrocytes: Form the myelin sheath around axons in the central nervous system

    Supporting Cells of the Peripheral Nervous System

    • Satellite cells: Help regulate the chemical environment of neurons and provide structural support
    • Schwann cells: Form the myelin sheath around axons in the peripheral nervous system

    Neurons

    • Long-living cells with a high metabolic rate
    • Composed of three main parts:
      • Cell body: Receptive or input region
      • Axon: Conducting component
      • Axonal endings: Secretory or output region
    • The cell body is also referred to as the perikaryon or soma
    • Cell bodies can range in size from 5 to 140 mm in diameter
    • Contain all cell organelles except centrioles
    • Nissl's bodies represent rough endoplasmic reticulum

    Neuron Structures and Locations

    • Nuclei, or nuclear areas: Collections of neuron cell bodies in the central nervous system
    • Ganglion: Collections of neuron cell bodies located outside the central nervous system
    • Tracts: Bundles of neuron axons in the central nervous system
    • Nerves: Bundles of neuron axons in the peripheral nervous system

    Neuron Types based on Structure

    • Multipolar neurons: have one axon and multiple dendrites
    • Bipolar neurons: have one axon and one dendrite
    • Unipolar neurons: Have a single process that extends from the cell body and divides into a peripheral and central branch. Unipolar neurons are derived from bipolar cells during embryonic development.

    Neuron Types Based on Function

    • Sensory, or afferent neurons: Transmit impulses from sensory receptors to the central nervous system.
    • Motor, or efferent neurons: Transmit impulses from the central nervous system to muscles and glands.
    • Association neurons, or interneurons: Located within the central nervous system; Connect sensory and motor neurons and are involved in complex processing and integrating information.

    Neurophysiology

    • Neurons are highly irritable
    • An action potential (AP) is generated due to ionic currents
    • Positive and negative charges are found across the plasma membrane
    • Membrane channels allow ions to cross
    • Ions diffuse down the electrochemical gradient

    Resting Membrane Potential

    • Ranges from -40 to -90 mV in most neurons
    • Extracellular fluid (ECF) contains a higher concentration of sodium ions (Na+)
    • Intracellular fluid (ICF) contains a higher concentration of potassium ions (K+) and negatively charged non-diffusible molecules
    • Sodium-potassium pump plays a critical role in maintaining the resting membrane potential by pumping sodium ions out of the cell and potassium ions into the cell

    Membrane Potentials

    • Depolarization: A change in membrane potential that makes the inside of the cell more positive.
    • Hyperpolarization: A change in membrane potential that makes the inside of the cell more negative.
    • Graded potential: A short-lived, localized change in membrane potential that can be either depolarizing or hyperpolarizing.
      • Receptor potential: A graded potential that is generated by a sensory receptor in response to a stimulus.
      • Postsynaptic potential: A graded potential that is generated at a synapse in response to the release of a neurotransmitter.

    Action Potential

    • Generated only by excitable membranes such as axons and muscle cells
    • Brief reversal of polarity across the membrane
    • Generation:
      • Involves the movement of Na+ and K+ ions across the membrane
      • Changes in membrane potential
      • Opening and closing of different types of channels
      • Different phases of action potential
      • The duration of the action potential

    Propagation of Action Potential

    • Flow of electrical current along the axon
    • Self-propagating current
    • Saltatory propagation occurs in myelinated axons
    • Strength is not decreased along the axon, it remains constant

    Action Potential Properties

    • Threshold: The minimum level of stimulation needed to generate an action potential
    • All-or-None phenomenon: Action potentials either occur at full strength or not at all.
    • Coding for stimulus intensity: The frequency of action potentials is used to code for stimulus intensity.
    • Absolute refractory period: A period of time during which a neuron cannot generate another action potential, no matter how strong the stimulus.
    • Relative refractory period: A period of time during which a neuron can generate another action potential, but only if the stimulus is stronger than usual.

    Synapses

    • Specialized junctions where neurons communicate with other neurons, muscle cells, or gland cells
    • Neurons have 1000-10,000 axonal terminals, which form synapses with other neurons
    • Neuromuscular junctions are synapses between a neuron and a muscle cell.
    • Neuro-glandular junctions are synapses between a neuron and a gland cell.

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    Description

    Test your knowledge of bones and skeletal tissues with this quiz. Explore the different types of bone and cartilage, their functions, and the overall structure of the skeletal system. Perfect for students learning about human anatomy.

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