Anatomy & Physiology Exam 2

Which microscopic structure is found only in the cardiac muscle tissue?

Intercalated discs

After the fusion of myoblasts, the muscle fiber loses its ability to:

Go through mitosis

What kind of bone is the vertebral disc?

An irregular one

Sequence of development of bone cells

Osteoprogenitor cells --> osteoblasts --> osteocytes

Epicondyle

Roughened project

Facet

Slightly concave or convex articulation surface

Meatus

Tube-like passageway

Describe how frequency of stimulation affects muscle tension. (see Figure 10.14)

When a second stimulus occurs after the refractory period of the first stimulus is over, but before the skeletal muscle fiber has relaxed, the second contraction will actually be stronger than the first. This phenomenon is called wave summation. When a skeletal muscle fiber is stimulated at a rate of 20-20 times per sec, it can only partially relax between stimuli. the result is a sustained by wavering contraction called unfused tetanus. When it is stimulated at an even higher rate, it is not able to relax at all. The result is fused tetanus.

Compare and contrast cervical, thoracic, and lumbar vertebrae.

There are 7 cervical vertebrae, 12 thoracic, 5 lumbar, 1 sacrum (five fused sacral vertebrae), and 1 coccyx (four fused coccygeal vertebrae). The cervical, thoracic, and lumbar vertebrae are movable, but the sacrum and coccyx are not.

Distinguish thick filaments from thin filaments.

Thin filaments are 8nm in diameter and 1-2 um long and composed mostly of actin while thick filaments are 16 nm in diameter and 1-2 um long and composed of myosin. Both are directly involved in the contractile process. Overall, there are two thin filaments for every thick filament in the regions of filament overlap. The filaments inside a myofibril do not extend the entire length of a muscle fiber. Instead, they are arranged in compartments called sarcomeres.

Crest

ridge

Compare the principal differences between female and male pelves.

-False pelvis: Female: Shallow Male: Deep -Pelvic brim: F: wide and more oval. M: narrow and heart-shaped -Pubic arch: F: Greater than 90 degrees. M: Less than 90 degrees -Greater sciatic notch: F: Wide, almost 90 degrees. M: Narrow about 70 degrees inverted V -Pelvic outlet: F: wider. M: narrower.

Describe several common types of fractures.

-Open (compound): The broken ends of the bone protrude through the skin. Conversely, a closed (simple) fracture does not break -Comminuted: The bone is splintered, crushed, or broken into pieces at the site of impact, and smaller bone fragments lie between the two main fragments. -Greenstick: A partial fracture in which one side of the bone is broken and the other side bends; similar to the way a green twig breaks on one side while the other side stays whole, but bends; occurs only in children, whose bones are not fully ossified and contain more organic material than inorganic material. -Impacted: One end of the fractured bone is forcefully driven into the interior of the other. -Pott: Fracture of the distal end of the lateral leg bone (fibula), with serious injury of the distal tibial articulation. -Colles: Fracture of the distal end of the lateral forearm bone (radius) in which the distal fragment is displaced posteriorly.

Describe common disorders of the axial skeleton

-Scoliosis:the most common of abnormal curves, it is the lateral bending of the vertebral column usually in the thoracic region. It may result from congenitally malformed vertebrae, chronic sciatica, and paralysis of muscles on one side of the vertebral column, poor posture, or one leg being shorter than the other. -Kyphosis: An increase in the thoracic curve of the vertebral column that produces a hunchback look. In TB of the spine, vertebral bodies may partially collapse, which causes an acute angular bending of the vertebral column. In the elderly, degeneration of the intervertebral disc lead to kyphosis. It can also be caused by rickets and poor posture. Common in females with advanced osteoporosis. -Lordosis: An increase in the lumbar curve of the vertebral column. May result from increased weight of the abdomen as in pregnancy or obesity, poor posture, rickets, osteoporosis or TB of spine. -Herniated disc: When the nucleus pulposus may herniate (protrude) posteriorly as a result of pressure or weakening of the discs that may be great enough to rupture the surrounding fibrocartilage or into one of the adjacent vertebral bodies

Describe the functional classification of joints.

-Synarthroses: An immovable joint. -Amphiarthroses: A slightly movable joint. -Diarthroses: A freely movable joint. All diarthroses are synovial joints. They have a variety of shapes and permit several different types of movement.

Describe how muscle action potentials arise at the neuromuscular junction. (see Figure 10.9 + 10.7)

1) A nerve impulse elicits a muscle action potential by first releasing Ach. A nerve impulse at the synaptic end bulbs stimulates the opening of voltage gated channels. Ca flows inward through the open channels. This stimulates the synaptic vesicles to undergo exocytosis. The synaptic vesicles then fuse with the motor neuron's plasma membrane which liberates Ach into synaptic cleft. It then diffuses across the synaptic cleft between the motor neuron and the motor end plate. 2) The binding of two molecules of Ach to the receptor on the motor end plates opens an ion channel in the Ach receptor. One open, small cations (mostly Na+) can flow across the membrane. 3) This next step details the production of muscle action potential. The inflow of Na+ makes the inside of the muscle fiber more + charged. This triggers a muscle action potential. Each nerve impulse normally elicits one muscle action potential. The muscle action potential then propagates along the sarcolemma into the system of T tubules. This causes stored Ca in the SR to release into sarcoplasm, which leads to contraction of the muscle fiber. 4) The final step is the termination of Ach activity. The effect of Ach binding lasts only for a short time because it is quickly broken down by enzyme AchE (which is located on the EC side of the motor end plate membrane) AchE breaks down Ach into acetate and choline -- these products can NOT activate the Ach receptor. *******The action potential depolarizes the synaptic end bulb, which causes openings of the voltage gates. The influx of calcium ions causes exocytosis of Ach. The neurotransmitter attaches to ligand gates. Opening of the channel allows an influx of sodium ions.

Describe a motor unit.

A motor unit consists of a somatic motor neuron plus all of the skeletal muscle fibers it stimulates. Typically, the muscle fibers of a motor unit are dispersed throughout a muscle rather than clustered together.

What kind of bone is the trapezoid?

A short bone

Describe the structure and function of synovial joints.

Articular (joint) capsule: A sleevelike capsule that surrounds the synovial joint and encloses the synovial cavity, and unites the articulating bones. It is composed of two layers, an outer fibrous membrane and an inner synovial membrane. The fibrous membrane consists of dense irregular CT that attach to the periosteum of the articulating bones. It is quite literally a thickened continuation of the periosteum between the bones. It is flexible and permits movement at a joint while its great tensile strength prevents the bone from dislocating. Ligaments-- fibers arranged as parallel bundles of dense regular CT that are highly adapted for resisting strains, are one of the the most important factors that hold bones close together in a synovial joint. Synovial membrane: The inner layer of the articular cartilage is known as the synovial membrane . It is composed of areolar CT with elastic fibers. They can also contain accumulations of adipose tissue (articular fat pads). articular cartilage: a layer of hyaline cartilage that covers articulating bones with a smooth, slippery surface but does not bind them together. Articular cartilage reduces friction between bones in the joint during movement. Helps absorb shock. synovial (joint) cavity: A unique characteristic of a synovial joint. The synovial cavity is situated between the articulating bones. it allows for considerable movement at a joint and are classified as freely movable (diarthroses). synovial fluid: The synovial membrane secretes synovial fluids, a viscous clear or pale yellow fluid. Consists of hyaluronic acid and interstitial fluid. It forms a thin film layer over the surfaces within the articular capsule. It reduces friction by lubricating the joint, absorbing shocks, and supplying O2 and nutrients to and removing CO2 and metabolic wastes from the chondrocytes within the articular cartilage. It also contains phagocytes that remove microbes and the debris that results from normal wear and tear in the joint.

What are the regions of the vertebral column?

Cervical (7), thoracic (12), lumbar (5), sacrum (1), coccyx (1)

Craniodiaphyseal dysplasia is a bone disorder that causes calcium to accumulate in the skull. These deposits of calcium decrease the foramina size in the skull. What would be an effect of smaller foramina?

Compression on cranial nerves may occur, inadequate blood flow to structures in the skull, intracranial hypertension (high BP)

Describe the functions of skeletal muscle proteins.

Contractile Proteins: Proteins that help generate force during muscle contractions. Myosin- Makes up a thick filament. A molecule consists of a tail and two myosin heads which bind to myosin binding sites on actin molecules of thin filament during muscle contraction. Actin- Main component of thin filament; each actin molecule has a myosin-binding site where myosin head of thick filaments binds during muscle contraction. Regulatory Proteins: Proteins that help switch muscle contraction process on and off. Tropomyosin- A component of thin filament. When skeletal muscle fiber is relaxed, tropomyosin covers myosin-binding sites of actin molecules which thereby prevent myosin from binding to actin. Troponin- A component of thin filament. When Ca ions bind to troponin, it changes shape. This conformational change moves tropomyosin away from myosin-binding sites on actin molecules, and muscle contraction begins as myosin binds to actin. Structural: Proteins that keep thick and thin filaments of myofibrils in proper alignment. They give myofibrils elasticity and extensibility and lick myofibrils to sarcolemma and ECM. Titin- Connects Z disc to M line of sarcomere, thereby helping to stabilize thick filament position. It can stretch and then spring back unharmed, and thus accounts for much of the elasticity and extensibility of myofibrils.

Define muscle fatigue and describe the factors that contribute to it.

Defined as the inability of a muscle to maintain force of contraction after prolonged activity. It mainly results from changes within muscle fibers. It is unclear the precise mechanisms that cause muscle fatigue -- however some factors that are though to contribute include inadequate release of Ca ions from the SR which results in a decline of Ca concentration in the sarcoplasm. Depletion of creatine phosphate also is associated with fatigue. Insufficient oxygen, depletion of glycogen and other nutrients, build up lactic acid and ADP, and failure of APs in the motor neuron to release enough Ach are also all factors contributing to muscle fatigue.

Compare three major methods of ATP production in muscle fibers. Describe when each method is used briefly how ATP is generated.

Creatine phosphate: When muscle fibers relax, they produce more ATP than they need for resting metabolism. Most of this excess ATP is used to synthesize creatine phosphate (an energy rich molecule that is found in muscle fibers). Creatine kinase catalyzes the transfer of one of the high energy phosphate groups from ATP to creatine, forming creatine phosphate and ADP. Creatine is a small amino-acid like structure that is synthesized in the liver, kidneys, and pancreas and then transported to muscle fibers. When contraction begins and the ADP levels start to rise, CK catalyzes the transfer of a high energy phosphate group from creatine phosphate back to ADP. This direct phosphorylation reaction quickly generates new ATP molecules. Since this occurs very rapidly, creatine phosphate is the first source of energy when muscle contraction begins. Other energy generating mechanisms in a muscle fiber take a relatively longer period of time to produce ATP compared to creatine phosphate. Between ATP and CP, there is enough energy storage for muscles to contract maximally for about 15 seconds. Anaerobic glycolysis: When muscle activity continues and the supply of creatine phosphate within the muscle fiber is depleted, glucose is catabolized to generate ATP. Glucose passes easily from blood into contracting muscle fibers via facilitated diffusion. It is also produced by a breakdown of glycogen in muscles. A series of reactions breaks down 1 glucose molecule into 2 molecules of pyruvic acid. This occurs in the cytosol and produces a net gain of 2 molecules of ATP. It does not require oxygen -- it can occur in aerobic and anaerobic settings. Ordinarily, the pyruvic acid will enter the mitochondria and then undergo oxygen-requiring reactions. This produces a large amount of ATP. During anaerobic conditions, pyruvic acid is converted to lactic acid. Each molecule of glucose forms 2 molecules of LA and 2 molecules of ATP. Lactic acid diffuses into the blood, where liver can convert to glucose. This process produces fewer ATP but it is faster. Provides enough energy for about 2 minutes of max muscle activity. Aerobic respiration: If oxygen is present, the pyruvic acid enters the mitochondria and goes through the krebs cycle and the ETC that produces ATP, CO2, H2O, and heat. Each molecule of glucose catabolized under aerobic conditions yields about 30-32 molecules of ATP. Aerobic respiration supplies enough ATP for muscles during periods of rest or light to moderate exercise provided sufficient oxygen and nutrients are available. In activities that last from several mins to an hour +, this type of respiration provides nearly all of the needed ATP.

Name the bones and surface markings of the appendicular skeleton. (figures from slides only)

Describe the relationship between the bones + surface markings

Describe the structural classification of joints.

Fibrous: There is no synovial cavity and the bones are held together by dense irregular connective tissue that is rich in collagen fibers. Cartilaginous: There is no synovial cavity, and the bones are held together by cartilage. Synovial: The bones forming the joint have a synovial cavity and are united by dense irregular connective tissue of an articular capsule, and often by accessory ligaments.

Describe the types of movements that can occur at synovial joints, noting which plane the motion takes place in

Flexion: A decrease in the angle between articulating bones. Usually occurs along sagittal plane. Extension: An increase in the angle between articulating bones, often to restore a part of the body to the anatomical position after it has been flexed. Usually occurs along sagittal plane. Hyperextension: Continuation of extension beyond the anatomical position. Examples include: bending the head backward at the atlanto-occipital and cervical intevertebral joints as in looking up at stars. Hyperextension of hinge joints, such as the elbow and knee joints is usually prevented by the arrangement of ligaments and the anatomical alignment of the bones. Abduction: The movement of a bone away from the midline. Usually occurs along the frontal plane. Ex: moving the humerus laterally at the shoulder joint, moving the palm laterally at the wrist joint, and moving the femur laterally at the hip joint. NOTE: The midline of the body is not used as a point of reference for abduction and adduction of the digits. Adduction: the movement of a bone toward the midline. Usually occurs along the frontal plane. Circumduction Rotation (medial + lateral): Movement of the distal end of a body part in a circle. Not an isolated movement by itself but rather a continuous sequence of flexion, abduction, extension, adduction, and rotation of the joint. It does not occur along a separate axis or plane of movement. Ex: moving the humerus in a circle at the shoulder joint. Elevation: Superior movement of a part of the body such as closing the mouth at the temporomandibular joint to elevate the mandible. Hyoid bones and ribs can be elevated or depressed. Depression: An inferior movement of a part of the body, such as opening the mouth to depress the mandible or returning shrugged shoulders to the anatomical position to depress the scapula and clavicle. Protraction: Movement of a part of the body anteriorly in the transverse plane. It's opposing movement is retraction. You can protract your mandible at the temporomandibular joint by thrusting it outward. Retraction: A movement of a protracted part of the body back to the anatomical position. Inversion: Movement f the sole medially at the intertarsal joints. The opposing movement is eversion. Physical therapists also refer to inversion combined with plantar flexion of the feed as supination. Eversion: A movement of the sole laterally at the intertarsal joints. Physical therapists also refer to eversion combined with dorisflexion of the feet as pronation. Dorsiflexion: The bending of the foot at ankle or talocrural joint in the direction of the dorsum. Dorsiflexion occuts when you stand on your heels. Its opposing movement is plantar flexion. Plantar flexion: Involves bending of the foot at the ankle joint in the direction of the plantar or inferior surface, as when you elevate your body by standing on your toes. Supination: A movement of the forearm at the proximal and distal radioulnar joints in which the palm is turned anteriorly. This position of the palms is one of the defining features of the anatomical position. It's opposing movement is pronation. Pronation: A movement of the forearm at the proximal and distal radioulnar joints in which the distal end of the radius crosses over the distal end of the ulna and the palm is turned posteriorly. Opposition: The movement of the thumb at the carpometacarpal joint in which the thumb moves across the plam to touch the tips of the fingers on the same hand. These opposable thumbs allow the distinctive digital movement that gives humans and other primates the ability to grasp and manipulate objects very precisely.

Sulcus

Grove

Head

Large round articulation surface supported by the neck of the bone

Condyle

Large round surface for smooth articulation surface

What term best describes this surface marking?

Meatus

Fissure

Narrow slit

Fossa

Shallow depression

Spinous process

Sharp and slender projection

Why will an individual who lifts weights build larger muscles?

Skeletal muscles increase number of myofibrils but not number of cells

Describe the six main functions of the skeletal system

Support: supports soft tissues and provides attachment points for the tendons of most skeletal muscles. Protection: Protects the most important internal organs from injury. Assistance in movement: most skeletal muscles attach to bone so that when they contract, they pull on the bones to produce movement. Mineral homeostasis (storage and release): bone tissue makes up about 18% of the weight. It stores calcium and phosphorus which contribute to bone strength. On demand, bone releases minerals into the blood to maintain critical mineral balances (homeostasis) and to distribute the minerals to other parts of the body. Blood cell production: Within certain bones, a connective tissue called red bone marrow produces RBCs, WBCs, and platelets by a process called hemopoiesis. Red bone marrow consists of developing blood cells, adipocytes, fibroblasts, and macrophages within a network of reticular fibers. It is present in developing bones of the fetus and some adult bones (like the hip, ribs, sternum etc) With age, much of the bone marrow changes from red to yellow. Triglyceride storage: yellow bone marrow with mostly adipose cells that store triglycerides. The stored triglycerides are considered to be a potential chemical energy reserve.

Describe osteoblasts:

-Bone building cells. -Active when blood calcium levels are high. -PTH causes these cells to become more active -Differentiates from osteoprogenitor -Overactivity can cause hypocalcemia

Describe the structure and function of each part of a long bone.

-Epiphysis: proximal and distal ends of the bone. -Metaphysis: the regions between the diaphysis and epiphysis. In a growing bone, each metaphysis contains an epiphyseal (growth) plate (made of hyaline cartilage) which allows the bone to grow in length. It is then replaced by epiphyseal line when the cartilage turns to bone. -Diaphysis: the bone's shaft/body - the long cylindrical main part of the bone. -Articular cartilage: Thin layer of hyaline cartilage covering the part of the epiphysis where the bone forms an articulation with another bone. It also reduces friction and absorbs shock at freely movable joints. Repair of damage is limited because articular cartilage lacks a perichondrium and lacks blood vessels. -Endosteum: a thin membrane that lines the medullary cavity. it contains a single layer of bone-forming cells and a small amount of connective tissue -Medullary cavity: hollow, cylindrical space within the diaphysis that contains fatty yellow bone marrow and numerous blood vessels in adults. This reduces the dense bony material where it is needed least. The long bones tubular designs provides max strength and min weight -Periosteum: A tough connective tissue sheath and its associated blood supply that surrounds the bone surface wherever it is not covered by articular cartilage. Composed of an outer fibrous layer of dense irregular connective tissue and an inner osteogenic layer that consists of cells. Some of the cells enable bone to grow in thickness, but not in length. It also protects the bone and assists in fx repair. it serves as an attachment point for ligaments and tendons. The periosteum is attached to underlying bone by perforating fibers (sharpays fibers) thick bundles of collagen.

Describe the structural and functional features of the bones in the vertebral column.

-Foramina: Cervical has one vertebral and two transverse. Thoracic and lumbar has one vertebral. -Spinous process: Cervical is slender, often bifid (C2-C6). Thoracic is long, fairly thick (most projected inferiorly) and lumbar has a short, blunt one that projects posteriorly. -Transverse processes: Cervical is small, thoracic is fairly large, and lumbar is large and blunt. -Articular facets: Cervical is absent, thoracic is present, and lumbar is absent. -Intervertebral discs: Cervical are thick relative to size of vertebral bodies. Thoracic is thin relative to size of vertebral bodies. Lumbar is thickest. -Nucleus pulposus and annulus fibrosus: Intervertebral discs are found between the bodies of adjacent vertebrae from the second cervical vertebra to the sacrum and account for about 25% of the height of the vertebral column. Each disc has an outer fibrous ring consisting of fibrocartilage called the annulus fibrosus (annulus = ringlike) and an inner soft, pulpy, highly elastic substance called the nucleus pulposus.

Classify bones based on their shape (using key examples from class)

-Long: Greater length than width and consist of a shaft and a variable number of extremities or ends and slightly curved for strength. Consists mostly of compact bone in diaphyses but lots of spongy bone on the ends. (e.g. femur, tibia, fibula, ulna, radius, phalanges) -Short: somewhat cube shaped and nearly equal in length and width. They consist of spongy bone tissue except at the surface, which has a thin layer of compact bone. (e.g. most carpal and tarsal bones) -Flat: Generally thin and composed of two parallel plates of compact bone tissue enclosing a layer of spongy tissue. Provides area for muscle attachment and stability. (e.g. cranial bones, sternum, ribs, thorax, scapulae. -Irregular: Complex in shape. They vary in spongy to compact ratio. (e.g. backbones, hip, certain facial bones, and calcaneus) -Sesamoid: Shaped like a sesame seed and develop in certain tendons where there are considerable friction, tension, and physical stress, such as the palms and soles. Typically measure only a few mm in diameter (with exception of knee cap). They are not always completely ossified. They protect tendons from excessive wear and tear, and they often change the direction of pull of a tendon which improves mechanical advantage of joint.

Describe the cellular composition of bone tissue and the function of each type of cell.

-Osteoprogenitor cells: Unspecialized bone stem cells derived from mesenchyme. Only bone cells to undergo cell division. the resulting cells develop into osteoblasts. Osteoprogenitor cells are found along the inner portion of the periosteum, in the endosteum, and in the canals within bone that contain blood vessels. -Osteoblasts: Bone building cells. They synthesize and secrete collagen fibers and other organic components needed to make ECM. They initiate calcification. As osteoblasts surround themselves with ECM, they become trapped in their secretions and become osteocytes. Osteocytes: Mature bone cells, are the main cells in bone tissue and maintain its daily metabolism, such as the exchange of nutrients and waste within the blood. They do not undergo cell division Osteoclasts: Huge cells derived from the fusion of many monocytes and are concentrated in the endosteum. On the side of the cell that faces the bone surface, the osteoclast;s plasma membrane is deeply folded in ruffle fashion. Here the cells releases lysosomal enzymes and acids that digest protein and mineral components of underlying ECM. This breakdown is termed bone resorption. It is part of normal development. Osteoclasts also help regulate blood calcium levels.

Describe the structure and functions of the three types of fibrous joints.

-Sutures: a fibrous joint composed of a thin layer of dense irregular connective tissue. They only occur between the bones of the skull. The irregular interlocking edges of sutures give them added strength. They are immovable (in adults) or slightly movable (in children). They play an important role in shock absorption. Some sutures are even replaced by bone in adults. These are referred to as synostosis or bony joint. **** The lambdoid suture articulates with the most bones in the skull -Syndesmoses: A joint in which there is greater distance between the articulating surfaces and more dense irregular connective tissue than in a suture. The dense irregular CT is typically arranged as a bundle (ligament), allowing the joint to permit limited movement. An example of this is the distal tibiofibular joint, where the anterior tibiofibular ligament connects the tibia and fibula. It permits slight movement (amphiarthrosis). Another example of syndesmosis is called gomphosis or dentoalveolar joint in which a cone shaped peg fits into a socket. The only examples of gomphoses in the human body are the articulations between the roots and the teeth and their sockets in the alveolar processes in the maxillae and mandible. A healthy gomphosis permits minute shock absorbing movements (amphiarthrosis) -Interosseous membranes: a substantial sheet of dense irregular CT that binds neighboring long bones and permits slight movement (amphiarthrosis) The two main IM joints in the body: one between the radius and the ulna and the other occurs between the tibia and the fibula. These strong CT sheets help hold these adjacent long bones together as well as define range of motion between the neighboring bones and provide increased attachment surface for muscles that produce movements of the digits of the hand and foot.

Outline the steps involved in the sliding filament mechanism of muscle contraction. (see Figure 10.6)

1) Myosin heads hydrolyzes ATP and becomes energized and oriented. Since a myosin head includes an ATP binding site that functions as an ATPase, this step is able to occur. The energy generated from this hydrolysis reaction is stored in the myosin head for later use during the cycle. This energy allows for the formation of the cocked position in which myosin can bind to actin. The products of ATP hydrolysis (ADP and phosphate group) are still bound to myosin head. 2) Myosin head binds to actin which forms a cross bridge. The myosin head then releases the previously hydrolyzed phosphate group. Since a myosin molecule technically has two heads, it is important to note that only one head binds to actin at a time. 3) Myosin head pivots, which pulls the thin filament past the thick filament toward center of the sarcomere (power stroke). The energy required to do the power stoke is derived from the energy stored in the myosin head from the hydrolysis of ATP. Once the power stroke occurs, the ADP is released from the myosin head. 4) As myosin head binds to ATP, the cross bridge detaches from actin. As ATP binds to the ATP binding site on the myosin head, the myosin head detaches from the actin.

Explain the sequence of events involved in fracture repair.

1) Reactive phase. This phase is an early inflammatory phase. Blood vessels crossing the fracture line are broken. As blood leaks from the torn ends of the vessels, a mass of blood (usually clotted) forms around the site of the fracture. This mass of blood, called a fracture hematoma (hē′‐ma‐TŌ‐ma; hemat‐ = blood; ‐oma = tumor), usually forms 6 to 8 hours after the injury. Because the circulation of blood stops at the site where the fracture hematoma forms, nearby bone cells die. Swelling and inflammation occur in response to dead bone cells, producing additional cellular debris. Phagocytes (neutrophils and macrophages) and osteoclasts begin to remove the dead or damaged tissue in and around the fracture hematoma. This stage may last up to several weeks. 2) Reparative phase: Fibrocartilaginous callus formation. The reparative phase is characterized by two events: the formation of a fibrocartilaginous callus, and a bony callus to bridge the gap between the broken ends of the bones. Blood vessels grow into the fracture hematoma and phagocytes begin to clean up dead bone cells. Fibroblasts from the periosteum invade the fracture site and produce collagen fibers. In addition, cells from the periosteum develop into chondroblasts and begin to produce fibrocartilage in this region. These events lead to the development of a fibrocartilaginous (soft) callus (fi‐brō‐kar‐ti‐LAJ‐i‐nus), a mass of repair tissue consisting of collagen fibers and cartilage that bridges the broken ends of the bone. Formation of the fibrocartilaginous callus takes about 3 weeks. 3) Bone remodeling phase. The final phase of fracture repair is bone remodeling of the callus. Dead portions of the original fragments of broken bone are gradually resorbed by osteoclasts. Compact bone replaces spongy bone around the periphery of the fracture. Sometimes, the repair process is so thorough that the fracture line is undetectable, even in a radiograph (x‐ray). However, a thickened area on the surface of the bone remains as evidence of a healed fracture.

Writer's cramp can occur in Anatomy and Physiology lecture class. What factor would most likely contribute to the muscles not being able to relax?

A deficit of ATP keeping myosin from detaching

What type of bone is the frontal bone

A flat bone

Define arthroplasty

A surgical procedure that replaces joints with artificial joints. The ends of damaged bones are removed and metal, ceramic, or plastic components are fixed in place. The goals of arthroplasty are to relieve pain and increase ROM.

Explain the phases of a twitch contraction.

A twitch contraction is the brief contraction of all muscle fibers in a motor unit in response to a single AP in its motor neuron. The stages of a twitch contraction are: Latent: A brief delay that occurs between application of the stimulus and the beginning of contraction. it lasts about 2 msec. The muscle action potential sweeps over the sarcolemma and Ca ions are released from the SR. Contraction: The second phase that lasts about 10-100 msec. Ca binds to troponin. Myosin binding sites on actin are exposed and cross bridges form. Peak tension develops in the muscle fiber. Relaxation: The third phase lasts around 10-100 msec. Ca in actively transported back into the SR and myosin binding sites are covered by tropomyosin, myosin heads detach from actin, and tension in the muscle fiber decreases. The actual duration of these periods depend on the type of skeletal muscle fiber. Refractory: A period of lost excitability. It is characteristic of all muscle and nerve cells. The duration varies with the muscle involved. Skeletal muscle has a short refrac period of about 1 msec while cardiac has one of about 250 msec.

Explain the effects of aging on joints.

Aging results in a decreased production of synovial fluid in joints. In addition, the articular cartilage thins with age and ligaments shorten and lose flexibility. These effects can be influenced by genetic factors and by wear and tear, and vary considerably for each person. Degenerative changes in joints can occur at as early as age 20 but usually do not occur until later. By 80, most people have some degeneration of their joints. Homeostatic imbalances also are age related. Nearly everyone over age 7 0 has some osteoarthritic changes. Stretching and aerobic exercises help with maintaining full ROM.

Describe the blood and nerve supply of bone

Blood is richly supplied with blood. Blood vessels, which are especially abundant in portions of bone containing red bone marrow, pass into bones from the periosteum. Nerves accompany the blood vessels that supply bones. The periosteum is rich in sensory nerves, some of which carry pain sensations. -Nutrient artery is located near the center of the diaphysis. it passes through a hole in compact bone called the nutrient foramen. It divides into proximal and distal branches that course toward each end of the bone. These branches supply both the inner part of compact bone tissue of the diaphysis and the spongy bone tissue and red bone marrow as far as epiphyseal plate. -Periosteal arteries are small arteries accompanied by nerves, enter the diaphysis through many interostenonic canals and supply the periosteum and outer part of the compact bone. -Metaphyseal arteries enter the metaphyses of a long bone, and together with the nutrient artery, supply the red bone marrow and bone tissue of the metaphyses. -Epiphyseal arteries enter the epiphyses of a long bone and supply the red bone marrow and bone tissue of epiphyses. -Artery/vein: veins that carry blood away from long bones are evident in three places: 1) one or two nutrient veins accompany the nutrient artery and exit through the diaphysis. 2) numerous epiphyseal veins and metaphyseal veins accompany their respective arteries and exit through the epiphyses and metaphyses respectively. 3) many small perosteal veins accompany respective arteries and exit through periosteum.

Discuss the structure and function of bursae and tendon sheaths.

Bursae are sac-like structures that are strategically situated to alleviate friction in some joints, such as the shoulder and the knee joints. They are not strictly apart of synovial joints, but they do resemble joint capsules because their walls consist of an outer fibrous membrane of thin, dense CT lined by a synovial membrane. They are filled with a small amount of fluid and can be located between skin and bones, tendons and bones, muscles and bones, or ligaments and bones. They cushion the movement of these body parts against one another. Tendon sheaths also reduce friction at joints. They are tubelike bursae that wrap around certain tendons that experience a considerable amount of friction as they pass through tunnels formed by CT and bone. The inner later of a tendon sheath is attached to the surface of a tendon. The outer layer, known as the parietal layer is attached to bone. Between the two layers is a cavity that contains a film of synovial fluid. A tendon sheath protects all sides of a tendon from friction as the tendon slides back and forth. They are found where tendons pass through synovial cavities, such as the tendon of the biceps brachii muscle at the shoulder joint. They are also found at the wrist and ankle and in the fingers and toes.

Which of the following bones is not apart of the axial skeleton?

Clavicle

Compare the structural and functional differences between compact and spongy bone tissue.

Compact bone tissue contains few spaces and is the strongest form of bone tissue. Found beneath the periosteum of all bones and makes up the bulk of the diaphysis of long bones. Provides protection and supports and resists stress from weight and movement. -Spongy bone tissue (trabecular or cancellous bone tissue) does NOT contain osteons. Spongy bone is always located in the interior of a bone, protected by a covering of compact bone. Consists of lamallae that are arranged in an irregular pattern of thin columns called trabeculae. Between the trabeculae are red bone marrow or yellow hone marrow depending on the bone. Each trabecula consists of concentric lamellae, osteocytes that lie in lacunae, and canliculi that radiate outward from the lacunae. -Osteon: repeating structural units in compact bone tissue. Aligned in the same direction and are parallel to the length of the diaphysis. Each osteon has concentric lamallae arranged around a canal. Concentric lamallae are circular plates of mineralized ECM surrounding a small network of blood vessels and nerves located in the central canal. Between concentric lamallae are small spaces called lacunae which contain osteocytes. Radiating from lacunae are canaliculi.

Describe four special properties of muscular tissue.

Excitability: Happens in both muscle and nerve cells. It is the ability to respond to certain stimuli by producing electric signals called action potentials. Two main types of stimuli trigger action potential in muscle cells: autorhythmic electrical signals and chemical stimuli. Contractility: The ability of the muscular tissue to contract forcefully when stimulated by an action potential. When a skeletal muscle contracts, it generates tension while pulling on its attachment points. If the tension is great enough to overcome the resistance of the object to be moved, the muscle will shorten and the movement occurs. Extensibility: The ability of muscular tissue to stretch (to an extent) without be damaged. The CT within the muscle limits the range of extensibility and keeps it within the range of the muscle cells. Smooth muscle is subject to the greatest amount of stretching, with cardiac muscle cells also stretching each time the heart fills with blood. Elasticity: The ability of muscular tissue to return to original length and shape after contraction or extension.

Distinguish between the false and true pelves.

False pelvis is upper. True pelvis is lower. The portion of the bony pelvis superior to the pelvic brim is considered to be the false pelvis. It is bordered by the lumbar vertebrae posteriorly, the upper portion of the hip bones laterally, and the abdominal wall anteriorly. The space enclosed by the false pelvis is part of the lower abdomen; contains the superior portion of the bladder and the lower intestines in both gender and the uterus, ovaries, and uterine tubes of the female. The portion of the bony pelvis INFERIOR to the pelvic brim is the true pelvis. It has an inlet, an outlet, and a cavity. It is bounded by the sacrum and coccyx posteriorly, inferior portions of the ilium and ischium laterally, and the pubic bones anteriorly. The true pelvis surrounds the pelvic cavity. The true pelvis contains the rectum and bladder in both genders, the vagina and cervix of the uterus in females, and the prostate in males. The pelvic axis is an imaginary line that curves through the true pelvis from the central point of the plane of the pelvic inlet to the central point of the plane of the pelvic outlet.

Describe the microscopic anatomy of skeletal muscle fibers.

Fascia:A dense sheet or broad band of irregular CT that lines the body wall and limbs and supports and surrounds the muscles with other organs of the body. It allows free movement of muscles, carries nerves, blood vessels, and lymphatic vessels as well as filling spaces between muscles. Wraps around groups of muscles. Tendon: A rope-like structure that attaches a muscle to the periosteum of a bone. Epimysium: The outer layer, encircling the entire muscle. Consists of dense irregular CT. Encircles muscle. Perimysium: A layer of dense, irregular CT but it surrounds groups of 10 to 100 or more muscle fibers which are separated into fascicles. Many fascicles are large enough to be seen with the naked eye. Encircles fascicles. Endomysium: Penetrates the interior of each fascicle and separates individual muscle fibers from one another. The endomysium is mostly reticular fibers. Separates muscle fibers. Myofibril: Little structures on the sarcoplasm -- they are the contractile organelles of skeletal muscle. They are roughly 2 mew meters in diameter and extend the entire length of a muscle fiber. Their prominent striations make the entire skeletal muscle look more striated. Composed of repeating units called sarcomeres. Sarcolemma: The plasma membrane of a muscle cell. Transverse (t) tubules: Tiny invaginations of the sarcolemma. They are filled with interstitial fluid. Muscle action potentials travel along the sarcolemma and through the T tubules, quickly spreading throughout the muscle fiber. This ensures excitability at the same instant regardless of which part of the muscle it is happening in. Sarcoplasm: The cytoplasm of a muscle fiber. Includes a substantial amount of glycogen which can be used for ATP synthesis. Sarcoplasmic reticulum: A fluid filled system of membraneous sacs that encircles each myofibril. In a relaxed muscle fiber, the SR stores calcium ions. The release of calcium from the SR triggers muscle contraction. Sarcomeres: Basic functional units of myofibrils. Z discs separate one sarcomere from the next.

Define key terms used to describe surface markings on bones.

Fissure: Narrow slit between adjacent parts of bones through which blood vessels or nerves pass. Foramen: Opening through which blood vessels, nerves, or ligaments pass. Fossa: Shallow depression Sulcus: Furrow along bone surface that accommodates blood vessel, nerve, or tendon. Meatus: Tubelike opening. Condyle: Large, round protuberance with a smooth articular surface at end of bone. Facet: Smooth, flat, slightly concave or convex articular surface. Head: Usually rounded articular projection supported on neck (constricted portion) of bone. Crest: Prominent ridge or elongated projection. Epicondyle: Typically roughened projection above condyle. Spinous process: Sharp, slender projection. Trochanter: Very large projection. Tubercle: Variably sized rounded projection. Tuberosity: Variably sized projection that has a rough, bumpy, service.

Describe hypertrophy and muscular atrophy

Hypertrophy: The muscle growth that occurs after birth occurs by enlargement of existing muscle fibers called muscular hypertrophy. It is due to an increased production of myofibrils, mitochondria, sarcoplasmic reticulum, and other organelles. It results from forceful and repetitive muscular activity such as strength training. Hypertrophied muscles contain more myofibrils, they are able to do perform more forceful contractions. Muscular Atrophy: A decrease in size of individual muscle fibers as a result of progressive loss of myofibrils. Atrophy that occurs because muscles are not used is referred to as disuse atrophy. As a result of this, the flow of nerve impulses to inactive skeletal muscle is greatly reduced -- at this point the condition is reversible. If instead the nerve supply is disrupted or cut, then the muscle undergoes denervation atrophy which is irreversible and replaced by fibrous connective tissue.

Distinguish between isotonic (concentric + eccentric) and isometric contractions

In an isotonic contraction, the tension developed in the muscle remains almost constant while the muscle changes its length. Isotonic contractions are used for body movements and for moving objects. There are two types of isotonic contraction: concentric and eccentric. If the tension generated in a concentric isotonic contraction is great enough to overcome the resistance of the object being moved, the muscle shortens and pulls on another structure, such as a tendon, to produce movement and to reduce the angle at a joint. When the length of a muscle increases during a contraction, the contraction is eccentric. The tension is exerted by the myosin cross bridges and resists movement of a load and slows the lengthening process. Repeated eccentric contractions produce more muscle damage and more delayed onset muscle soreness than concentric contractions In an isometric contraction, the tension generated is not enough to exceed the resistance of an object to be moved, and the muscle does not change its length. These contractions are important for maintaining posture and for supporting objects in a fixed position. They do not result in body movement, but they do expend energy. These type of contractions are important because they stabilize some joints as others are moved. Most activities include both isotonic and isometric contractions.

Describe the steps of intramembranous and endochondral ossification.

Intramembraneous ossification: Bone forms directly within mesenchyme, which resembles membranes. It is the simpler of the two methods. The flat bones of the skull, most of the facial bones, and medial part of clavicle are formed this way. Steps 1) Development of the ossification enter. Chemical signals cause the cells of the mesenchyme to cluster and differentiate into first osteoprogenitor cells, and then into osteoblasts. Osteoblasts secrete the organic ECM of bone until they are surrounded by it. 2) Calcification: secretion of ECM stops, and the cells, now called osteocytes lie in lacunae and extend their narrow cytoplasmic processes into canalicili that radiate in all directions. Within a few days, the calcium and other mineral salts are deposited in ECM and harden. 3) Formation of trabeculae: the bone ECM forms and develops into trabeculae that fuse with one another to form spongy bone around the network of blood vessels in the tissue. CT associated with blood vessels in trabeculae differentiate into red bone marrow. 4) Development of the periosteum: Mesenchyme condenses at the periphery of the bone and develops into periosteum. Eventually, thin layer of compact bone replaces the surface layers of the spongy bone, but spongy bone remains in the center. Endochondral ossification: bone forms within hyaline cartilage that develops from mesenchyme. Most bones of the body are formed this way. Process is best observed in a long bone. Steps: 1) Development of cartilage model: chemical messages cause the cells in mesenchyme to crowd together in the general shape of the future bone, and then develop into chondroblasts secrete cartilage extracellular matrix, producing a cartilage model consisting of hyaline cartilage. A covering called the perichondrium develops around the cartilage model. 2) Growth of the cartilage model: Once chondroblasts become deeply buried in the cartilage ECM. The cartilage model grows in length by continual cell division of chondrocytes, accompanied by further secretion of the cartilage ECM. This type of growth is known as interstitial growth results in an increase in length. New chondroblasts that develop from the perichondrium is responsible for the growth of the cartilage in thickness. This process is called appositional growth. Calcification begins to occur as cartilage model continue to grow. Other chondrocytes within the calcifying cartilage begin to die because nutrients can no longer diffuse quickly enough through the extracellular matrix. As they die, the spaces left behind merge into small cavities called lacunae. 3) Development of primary ossification center: proceeds inward from the external surface of the bone. A nutrient artery penetrates the perichondrium and the calcifying cartilage model through a nutrient foramen in the midregion of the cartilage model, stimulating osteoprogenitors in the perichondrium to differentiate into osteoblasts. Once perichondrium starts to form bone, it is known as periosteum. Periosteal capillaries grow into the disintegrating calcified cartilage, which in turn induces growth of a primary ossification center. Osteoblasts then begin to deposit bone ECM over remnants of calcified cartilage which forms spongy bone trabeculae. Primary ossif. spreads from this central canal to both ends of the cartilage model 4) Development of the medullary cavity: As primary ossif. center grows toward ends of the bone, osteoclasts break down some of the new spongy bone. As a result, a cavity is formed. 5) Development of the secondary ossification centers: develops usually around the time of birth. Spongy bone remains in the interior of epiphysis so no medullary cavity. It proceeds outward from the center of the epiphysis toward the OUTER surface of the bone. 6) Formation of articular cartilage and the epiphyseal growth plate: Hyaline that covers the epiphysis becomes articular cartilage.

Initial formation of the frontal bone is done through which type of ossification?

Intramembranous

Explain how bone grows in length and thickness.

LENGTH: The growth in length of long bones involves the following two major events: (1) interstitial growth of cartilage on the epiphyseal side of the epiphyseal plate and (2) replacement of cartilage on the diaphyseal side of the epiphyseal plate with bone by endochondral ossification. Steps: 1) Zone of resting cartilage. This layer is nearest the epiphysis and consists of small, scattered chondrocytes. The term "resting" is used because the cells do not function in bone growth. Rather, they anchor the epiphyseal plate to the epiphysis of the bone. 2) Zone of proliferating cartilage. Slightly larger chondrocytes in this zone are arranged like stacks of coins. These chondrocytes undergo interstitial growth as they divide and secrete extracellular matrix. The chondrocytes in this zone divide to replace those that die at the diaphyseal side of the epiphyseal plate. 3) Zone of hypertrophic cartilage (hī‐per‐TRŌ‐fik). This layer consists of large, maturing chondrocytes arranged in columns. 4) Zone of calcified cartilage. The final zone of the epiphyseal plate is only a few cells thick and consists mostly of chondrocytes that are dead because the extracellular matrix around them has calcified. Osteoclasts dissolve the calcified cartilage, and osteoblasts and capillaries from the diaphysis invade the area. The osteoblasts lay down bone extracellular matrix, replacing the calcified cartilage by the process of endochondral ossification. Recall that endochondral ossification is the replacement of cartilage with bone. As a result, the zone of calcified cartilage becomes the "new diaphysis" that is firmly cemented to the rest of the diaphysis of the bone. THICKNESS: Like cartilage, bone can grow in thickness (diameter) only by appositional growth STEPS 1) At the bone surface, periosteal cells differentiate into osteoblasts, which secrete the collagen fibers and other organic molecules that form bone extracellular matrix. The osteoblasts become surrounded by extracellular matrix and develop into osteocytes. This process forms bone ridges on either side of a periosteal blood vessel. The ridges slowly enlarge and create a groove for the periosteal blood vessel. 2) Eventually, the ridges fold together and fuse, and the groove becomes a tunnel that encloses the blood vessel. The former periosteum now becomes the endosteum that lines the tunnel. 3) Osteoblasts in the endosteum deposit bone extracellular matrix, forming new concentric lamellae. The formation of additional concentric lamellae proceeds inward toward the periosteal blood vessel. In this way, the tunnel fills in, and a new osteon is created. 4) As an osteon is forming, osteoblasts under the periosteum deposit new circumferential lamellae, further increasing the thickness of the bone. As additional periosteal blood vessels become enclosed as in step 1, the growth process continues.

Explain how blood calcium level is regulated and its importance in the body.

One way to maintain the level of calcium in the blood is to control the rates of calcium resorption from bone into blood and of calcium deposition from blood into bone. Both nerve and muscle cells depend on a stable level of calcium ions (Ca2+) in extracellular fluid to function properly. Blood plasma level is closely regulated between 9-11 mg/100 mL. Even small changes in Ca2+ concentration outside this range may prove fatal—the heart may stop (cardiac arrest) if the concentration goes too high, or breathing may cease (respiratory arrest) if the level falls too low. The role of bone in calcium homeostasis is to help "buffer" the blood Ca2+ level, releasing Ca2+ into blood plasma (using osteoclasts) when the level decreases, and absorbing Ca2+ (using osteoblasts) when the level rises. Calcium is regulated primarily by the hormone PTH (parathyroid hormone) secreted by the parathyroid glands. It increases blood Ca 2+ levels (negative feedback). If blood calcium is low, PTH gland receptors detect this change and increase their production of a molecule known as cyclic AMP. PTH recognizes cAMP and then, and ramps up synthesis of PTH which releases more into the blood, therefore increasing Ca2+. Higher PTH increases the number and activity of osteoclasts, which step up the place of bone resorption. The resulting release of Ca2+ from bone into blood returns the blood Ca2+ level to normal. ***************************PT gland cells are the receptors and respond to low blood calcium levels. cAMP input activates the control center when blood calcium is low. Osteoblasts and kidney cells are the effectors of PTH. The kidney increases reabsorption of calcium in response to PTH. Calcitriol is secreted in response to PTHs effects on the kidneys.

Foramen

Opening or hole

Describe the six types of synovial joints.

Plane: Flat or slightly curved articulating surfaces of bones in a plane joint. They permit back and forth movement. Biaxial or triaxial Hinge: A hinge joint is when the convex surface of one bone fits into the concave surface of another. They produce an angular, opening and closing motion like the hinge of a door. They are uniaxial because they allow motion around a single axis. They permit only flexion and extension. Examples are the knee, elbow, ankle, and interphalangeal joints. Pivot: When the rounded or pointed surface of one bone articulates with a ring formed partly by another bone and partly by a ligament. Uniaxial because allows rotation only around its own longitudinal axis. Examples include the atlanto-axial joint (shaking your head) and the radioulnar joints. Condyloid: When the convex oval-shaped projection of one bone fits into the oval shaped depression of another bone. Biaxial because the movement it permits is around to axes (flexion-extension and abduction-adduction) plus limited circumduction. Examples include the wrist and metacarpophalangeal joints. Saddle: When the articular surface of one bone is saddle-shaped and the articular surface of the other bone fits into the saddle as a sitting rider would sit. The movements a t a saddle joint are the same as those at a condyloid joint: biaxial. Examples include carpometacarpal joint between the trapezium of the carpus and metacarpal of the thumb. Ball-and-socket: Consists of the ball-like surface of one bone fitting into a cuplike depression of another bone. They are considered to be triaxial, permitting movements around three axes: flexion-extension, abduction-adduction, and rotation. Examples are the shoulder and hip joints.

Describe the importance of calcium in muscles

Plays a major role in contraction and relaxation of muscles. Voltage gated Ca2+ channels are located in the T-tubule membrane and are arranged in tetrads. The main role of these channels are to serve as voltage sensors that trigger the opening of the Ca2+ release channels. Ca2_ release channels are present in the SR. When a skeletal muscle fiber is at rest, the part of the Ca release channel that extends into the sarcoplasm is blocked by a given cluster of voltage gated Ca channels, preventing CA from leaving the SR. When a skeletal muscle is excited and an action potential travels along the T tubule, the voltage gated Ca channels detect the change in voltage and undergo a change that causes Ca release channels to open. Once this occurs, a large amount of Ca flows into the sarcoplasm around thick and think filaments. In short, all of this leads to contraction. Calsequestrin bind to Ca 2+ which allows even more Ca2+ to be stored within the SR. In a relaxed muscle fiber, the concentration of Ca is 10000 times higher in the SR than in the sarcoplasm. ************Muscle contractions, nerve signaling, blood clotting, and enzymatic reactions

Describe four key functions of muscular tissue.

Producing movement: Movements of the whole body such as walking or running, and localized movements such as grasping a pencil, keyboarding, or nodding the head rely on the functioning of skeletal muscles, bones, and joints. Stabilizing position: Skeletal muscle contractions stabilize the joints and help maintain body positions such as standing or sitting. Postural muscles contract simultaneously while you are awake. Moving substances within the body: Storage is accomplished by sustained contractions of ringlike bands of smooth muscle called spinchters which prevent the outflow of contents of a hollow organ. Contraction and relaxation of the smooth muscle in the walls of vessels help adjust blood vessel diameter and thus regulate the rate of blood flow. Smooth muscle contractions also move food and other things through GI tract. Skeletal muscle contractions promote the flow of lymph and aid the return of blood in veins to the heart. Generating heat: As muscular tissue contracts, it produces heat, a process known as thermogenesis. Much of the heat generated by muscle is used to maintain normal body temp. Involuntary contractions of skeletal muscles (shivering) can increase the rate of heat production.

Identify the major joints of the body by location, classification, and movements

Shoulder joint: A ball and socket joint formed by the head of the humerus and the glenoid cavity of the scapula. Shoulder joints allow flexion, extension, hyperextension, abduction, adduction, medial rotation, lateral rotation, and circumduction of the arm. It has more freedom of movement than any other joint of the body. This is due to the looseness of the articular capsule and the shallowness of the glenoid cavity in relation to the large size of the heard of the humerus. The rotator cuff muscles work as a group to hold the head of the humerus in the glenoid cavity. Elbow joint: A hinge joint formed by the trochlea and capitulum of the humerus, the trochlear notch of the ulna, and the head of the radius. The elbow joint allows flexion and extension of the forearm. Hip joint: A ball and socket joint formed by the head of the femur and the acetabulum of the hip bone. It allows flexion, extension, abduction, adduction, lateral rotation, medial rotation, and circumduction of the thigh. It has a very strong articular capsule and accessory ligaments which is why it is so stable. However, the stability also limits ROM. Flexion is limited by anterior surface of the thigh coming into contact with the anterior abdominal wall when the knee is flexed and by tension of the hamstring muscles when the knee is extended. Extension, abduction, and adduction are also limited as well as medial and lateral rotation. Knee joint: The largest and most complex joint of the body. A modified hinge joint that consists of three joints within a single synovial cavity. The knee joint allows flexion, extension, slight medial rotation, and lateral rotation of the leg in the flexed position.

Contrast the three types of muscular tissue in terms of location, function, appearance, and control.

Skeletal: Most skeletal muscles move the bones of the skeleton. It is striated and works in a voluntary matter. It is controlled by neurons of the somatic (voluntary) nervous system. Cardiac: Forms most of the heart wall. It is also striated but involuntary. Autorhythmicity keeps the heart beating, while several neurotransmitters and electrolytes affect the rhythm. Smooth: Located in the walls of hollow internal structures, such as blood vessels, airways, and most organs in the abdominopelvic region. It is also found in the skin, attached to hair follicles. It lacks striations and is usually involuntary (some muscles, such as those that move food through the digestive tract has some autorhytmacity to them). Like cardiac muscle, it is regulated by neurons that are part of the autonomic nervous system. Smooth muscle fibers contain thin and thick filaments, as well as intermediate filaments, but none of them are arranged in sarcomeres.

Compare the three main types of muscle fibers based on their size, mitochondria, capacity for generating ATP + method used, fatigue resistance, glycogen stores, order of recruitment, primary functions

Slow oxidative fibers (Type I): Appear dark red because they contain a lot of myoglobin and many blood capillaries. They have many large mitochondria so they generate ATP mainly by aerobic respiration. They are said to be slow because the ATPase in the myosin heads hydrolyzes ATP relatively slow, and the contraction cycle proceeds at a slower pace than in fast fibers. They have a slow speed of contraction. Their twitch contractions last from 100-200 msec and they take longer to reach peak tension. Slow fibers are very resistant to fatigue and are capable of prolonged sustained contractions for many hours. Adapted for maintaining posture and for aerobic, endurance-type activities. Fast oxidative-glycolytic fibers (Type IIa): Typically the largest fibers. they contain large amounts of myoglobin and many blood capillaries. They have a dark red appearance. They can also generate considerable ATP by aerobic respiration, which gives them a moderately high resistance to fatigue. Intracellular glycogen levelis high, they also generate ATP by anaerobic glycolysis. They are considered to be fast fibers because the ATPase in their myosin heads hydrolyzes ATP 3-5 x faster than the myosin ATPase is SO fibers. FOG fibers reach peak tension more quickly than SO fibers, but are briefer in duration (less than 100 msec). Contributes to activities like walking and sprinting. Fast glycolytic (Type IIx): These fibers have low myoglobin content and relatively few blood capillaries and few mitochondria. As a result, they appear white in color. They contain large amounts of glycogen and generate ATP mainly by glycolysis. Due to their ability to hydrolyze ATP rapidly, FG fibers contract strongly and quickly. They are fast twitch fibers that are adapted for intense anaerobic movements of short duration like weight lifting or throwing a ball. they fatigue quickly. The FG fibers of a weight lifter may be 50% larger than those of a sedentary or an endurance athlete because of increased synthesis of muscle proteins. The overall result is muscle enlargement due to hypertrophy of the FG fibers.

Describe six factors that influence the type of movement and ROM possible at a synovial joint

Structure of bones: Determines how closely the bones can fit together. The articular surfaces of some bones have a complementary relationship. This spatial relationship is very obvious at the hip joint, where the head of the femur articulates with the acetabulum of the hip bone. An interlocking fit allows for rotational movement. Strength of ligaments: The different components of fibrous capsule are tense or taut only when the joint is in certain positions. They direct the movement of the articulating bones with respect to each other. Arrangement of muscles: Muscle tension reinforces the restraint placed on a joint by its ligaments and therefore restricts movement. This can be seen in the hip joint when the thigh is flexed. Contact of soft parts: The point at which one body surface contacts another may limit mobility. An example is when you bend your arm at the elbow, it can move no farther after the anterior surface of the forearm meets with and presses against the biceps brachii muscle of the arm. Joint movement could also be restricted due to adipose tissue. Hormones: Joint flexibility can be affected by hormones. Relaxin for example, increases the flexibility of the fibrocartilage of the pubic symphysis and loosens the ligaments between the sacrum, hip bone, and coccyx toward the end of pregnancy. Disuse: Movement at a joint may be restricted if a joint has not been used for a long period of time. For example, an elbow in a cast ROM may be limited for a time after the cast is removed. This can also be a result of decreased synovial fluid, diminished flexibility of ligaments and tendons, and muscular atrophy.

Describe the structure and functions of the three types of cartilaginous joints.

Synchondroses: A joint in which the connecting material is hyaline cartilage and is slightly movable to immovable. An example of this type of joint is the first rib and manubrium of the sternum. Symphyses: A join tin which the ends of the articulating bones are covered with hyaline cartilage. A broad flat disc of fibrocartilage connects the bone. All symphyses occurs in the mid line of the body; the pubic symphysis is an example of a symphysis. Other examples include the junction of the manubrium and body of sternum and at the intevertebral joints between the bodies of vertebrae. A symphysis is a slightly movable joint. Epiphyseal growth plates: hyaline cartilage growth centers during endochondral bone formation, not joints associated with movements. An example of this is the epiphyseal growth plate that connects the epiphysis and diaphysis of a growing bone. Functionally, it is an immovable joint. When bone elongation ceases, bone replaces the hyaline cartilage and becomes a bony joint.

Describe the process involved in bone remodeling.

The bone is continually renewing itself. Bone remodeling is considered the ongoing replacement of old bone tissue by new bone tissue. It involves bone resorption, the removal of minerals and collagen fibers from bone by osteoclasts, and bone deposition, the addition of minerals and collagen fibers to bone by osteoblasts. Thus, bone resorption results in the destruction of bone extracellular matrix, while bone deposition results in the formation of bone extracellular matrix. Remodeling also removes injured bone, replacing it with new bone tissue. Remodeling may be triggered by factors such as exercise, sedentary lifestyle, and changes in diet. During the process of bone resorption, an osteoclast attaches tightly to the bone surface at the endosteum or periosteum and forms a leakproof seal at the edges of its ruffled border Then it releases protein‐digesting lysosomal enzymes and several acids into the sealed pocket. The enzymes digest collagen fibers and other organic substances while the acids dissolve the bone minerals. Working together, several osteoclasts carve out a small tunnel in the old bone. The degraded bone proteins and extracellular matrix minerals, mainly calcium and phosphorus, enter an osteoclast by endocytosis, cross the cell in vesicles, and undergo exocytosis on the side opposite the ruffled border. Now in the interstitial fluid, the products of bone resorption diffuse into nearby blood capillaries. Once a small area of bone has been resorbed, osteoclasts depart and osteoblasts move in to rebuild the bone in that area.

Describe how the skeleton is organized into axial and appendicular divisions.

There are 80 bones of the axial skeleton (8 cranium bones, 14 facial bones, 6 auditory ossicles, 26 vertebral column, 1 sternum bone, and 24 rib bones) and 126 bones of the appendicular skeleton (2 clavicles, 2 scapula, 2 humerus, 2 ulna, 2 radius, 16 carpals, 10 metacarpals, 28 phalanges, 2 hip/pelvic, 2 femurs, 2 patella, 2 fibula, 2 tibia, 14 tarsals, 10 metatarsals, and 28 phalanges) bones of the upper and lower limbs plus the bones forming the girdle that connect the limbs to the axial skeleton.

Describe the principal surface markings on bones and the functions of each.

There are two major types of surface markings: (1) depressions and openings, which allow the passage of soft tissues (such as blood vessels, nerves, ligaments, and tendons) or form joints, and (2) processes, projections or outgrowths that either help form joints or serve as attachment points for connective tissue (such as ligaments and tendons).

Explain the cause of rigor mortis

This happens after death. Cellular membranes become leaky and calcium ions leak out of the sarcoplasmic reticulum into the sarcoplasm which results in myosin heads binding to actin. ATP synthesis ceases pretty much right after breathing stops--this means that the cross bridges cannot detach from the actin. Muscles become in a state of rigidity. It begins 3-4 hours after death and lasts about 24 hours. it stops because proteolytic enzymes from lysosomes digest the cross-bridges.

Describe the length-tension relationship in skeletal muscles (see Figure 10.8)

This relationship indicates how the forcefulness of muscle contraction depends on the length of the sarcomeres within a muscle before contraction begins. When the sarcomere is at a length of about 2.0-2.4 uM, the zone of overlap in each sarcomere is optimal so that the muscle fiber can develop max tension. Max tensions occurs when the zone of overlap between a thick and thin filaments extends from the edge of the H zone to one end of a thick filament.

Tuberosity

Variably sized projecting that is rough

Tubercle

Variably sized rounded projection

Trochanter

Very large projection

Identify the regions and normal curves of the vertebral column.

When looking at the adult vertebral column from the side, you can see four slight bends called normal curves. Relative to the front of the body, the cervical and lumbar curves are convex (bulging out); the thoracic and sacral curves are concave (cupping in). The curves of the vertebral column increase its strength, help maintain balance in the upright position, absorb shocks during walking, and help protect the vertebrae from fracture. Various conditions may exaggerate the normal curves of the vertebral column, or the column may acquire a lateral bend, resulting in abnormal curves of the vertebral column. Three such abnormal curves—kyphosis, lordosis, and scoliosis ****** The two primary curves of the adult vertebral column are the thoracic and sacral curves.

Distinguish bands + zones within a sarcomere

Z disc: Narrow, plate shaped regions of dense protein material that separate one sarcomere from the next. A band: The darker middle part of the sarcomere. it extends the entire length of thick filaments. Toward each end of the A band is a zone of overlap, where the thick and thin filaments lie side by side. ********* The light A bands remain at a constant length. I band: A lighter less dense area that contains the rest of the thin filaments but no thick filaments. H zone: A narrow H zone in the center of each A band contains thick but not thin filaments. M line: Supporting proteins that hold the thick filaments together at the center of the H zone form the M line -- it is named because it is at the middle of the sarcomere.