Anatomy Lecture Test 2

Describe best practices for measuring growth in children 2 and under (i.e., up to 3 years) of age? in children 3 years of age and older?

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Describe the terminology and types of range of motion of the major joints.

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Describe what is assessed during the physical examination of the musculoskeletal system.

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Identify normal growth rates by age.

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Identify the factors that can cause variations in growth.

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Identify ways in which "heightism" can affect individuals.

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In indirect attachments, what tissues are involved in transmitting pulling (i.e., tension forces generated during contraction) forces from the muscle fiber to the bone?

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Provide several examples of disorders or diseases might adversely affect linear growth?

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What are the anatomical landmarks for correctly measuring head circumference in children (up to the age of 3)?

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What are the indicators of constitutional growth delay?

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What is "normal short stature" for a woman? for a man?

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What is channelization? What is the effect of channelization on growth?

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What is importance of growth assessment in children?

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What is the definition of growth failure in children 3 yr through puberty?

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What might be "red flags" explaining delayed growth due to psychosocial deprivation?

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Which contracts more quickly -smooth or skeletal muscle? Which contracts more efficiently? Which is most fatigue-resistant?

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Be able to describe the general function of each of the synovial joint structures.

6. Function of synovial joint structures: a. Articular cartilage—reduce friction, shock absorber b. Fibrous capsule—acts as sleeve around joint cavity, prevents dislocation, allows movement but resists stress and strain from many directions c. Synovial membrane—specially adapted to secrete the synovial fluid into the joint cavity d. Synovial fluid—reduces friction, supplies nutrients and oxygen to hyaline (articular) cartilage and removes metabolic wastes from the articular cartilage, shock absorber e. Articular discs—adds extra padding to joint, not attached, shock absorption, form cup for condyles so aid in joint stability by making a better fit, channels the flow of synovial fluid at the joint during movement f. Ligaments—slightly elastic and hold articular bones together (bone←→bone) g. Articular capsule—has rich blood and nerve supply that monitors position and movement of joints and allows for posture and coordination

Why does a contracture develop?

A contracture develops when a joint is not moved over a long period of time. The muscles, tendons, and ligaments atrophy and hold the joint in a flexed position.

How are joint stability and range of motion related?

A joint cannot be both highly mobile and very stable therefore joint stability and ROM are inversely related.

Describe the general structure of a long bone.

A long bone has a shaft (diaphysis) surrounded by the periosteum, except at the ends where it is surrounded by the articular cartilage. Inside the disphysis is the medullary cavity, which is lined by spongy bone and endosteum. The nutrient artery penetrates the periosteum, compact bone and into the endosteum. Spongy bone is also found at the ends of the long bone called the epiphysis. The area between the epiphysis and diaphysis on each end are referred to as the metaphysis and within this space of the bone are the epiphyseal lines. Sharpey's (collagen) fibers hold the periosteum to the bone matrix.

What is a motor unit?

A motor unit consists of a single motor neuron and all of the skeletal muscle fibers that it innervates; how muscles are organized. The motor units vary in size and the fibers of a motor unit are scattered throughout the muscle

When does a muscle begin to develop (or exert) external tension?

A muscle begins to develop and exert external tension when internal tension exceeds the resistance. This internal tension must develop before the muscle can exert a pull on the bone.

What is a muscle twitch?

A muscle twitch is the response of an isolated muscle or motor unit to a single, brief, threshold unit. It can be strong or weak depending on the amount of voltage/#of muscle fibers applied)

Describe the structure of a myosin molecule. How are myosin molecules arranged to make up a thick filament?

A myosin molecule is the most abundant protein in the thick filaments of sarcomeres. They are made of two two filaments that twist to form a long tail and at the end, the globin tails protrude. They contain a hinge region that allows the head of the protein to pivot back and forth. The head contains myosin ATPase and the tails point to and are anchored in the M line. Each head is oriented toward 1 of 6 surrounding thin filaments

Describe the structure of the neuromuscular junction.

A neuromuscular junction (NMJ) is where contact and communication occurs between axonal endings of an a-motor neuron and the muscle fiber it innervates. It contains axonal endings called synaptic terminals, which are scattered and have vesicles with neurotransmitters. The synaptic terminals also contain mitochondria (high ATP demand) and synaptic vesicles. The NMJ releases the neurotransmitter acetylcholine (ACh) at the synaptic cleft across the synapse. The motor end plate is the region of the sarcolema opposite the synaptic terminal where it modifies itself by infolding to increase the SA and hold more receptors for neurotransmitters. The motor end plate contains many ACh receptors that are associated with the sodium ion channel (ligand gated); when ACh binds, the channel open and sodium can flow into the muscle fiber. Finally the synaptic cleft is important in the NMJ because activity in the synaptic cleft breaks down ACh by function of acetylcholinesterase, which prevents continued muscle activation in the absence of additional nervouse system activation by breaking down ACh.

What causes myosin to detach from actin after the power stroke is completed?

A new ATP binding to the myosin head causes the myosin that has completed the power stroke to detach from the active site on actin

What is a sarcomere?

A sarcomere is measured from one Z line to the next Z line. It is the organizing unit of myofilaments. It contains proteins actin, myosin and elastic filaments (titin). It is the smallest contractile unit of a muscle. They run from end to end of a myofibril (many make up each one). The cross section of a sarcomere has each thick filament surrounded by 6 thin filaments and each thin filament surrounded by 3 thin filaments.

periosteal bud

A vascular connective tissue bud from the perichondrium that enters the cartilage of a developing long bone and contributes to the formation of a center for ossification

When is the (ADP + Pi ) which fueled the power stroke (#44) released from the myosin head?

ADP + Pi is released as the myosin attaches to the active site to fuel the power stroke

At what point in crossbridge cycling (#44) does ATP become hydrolyzed, and provide the energy for activation of the myosin head?

ATP is hydrolyzed by ATPase. It occurs in the myosin head after the power stroke of one cross bridge cycle, as a new ATP binds to detach one cross bridge and hydrolyze to revert the head back to the cocked position where it holds ADP and Pi

Identify the ways in which ATP is used to directly power muscle contraction events.

ATP is used directly in two muscle contraction events; cross bridge cycling (movement and detachment) to activate the myosin heads AND in ATP dependent Ca pumps in the SR that resequester Ca when the stimulus is no longer present

What is acetylcholine? What role does it play at the neuromuscular junction?

Acetylcholine (ACh) is a neurotransmitter that is released at the synaptic cleft across the synapse of the NMJ. It binds to ACh receptors on the muscle fiber opening Na+ channels to flow into the muscle fiber triggering a muscle action potential

Describe the structure of an actin molecule. How are individual actin monomers arranged to make up a thin filament?

Actin molecules are composed are the thin filaments but they are not composed of only actin. These molecules are contain actin proteins as their primary contractile proteins. They are in the G form (individual globin proteins) that are polymerized into long actin filaments called F actin. The G actin positions itself along the structural protein nebulin that consists of two strands that go all the way through and stabalize G actin. Each G actin has an active site that is covered by tropomyosin when relaxed and open when contracting. There are two strands of tropomyosin, one for each actin filament. Troponin is a regulatory protein that consists of three globular subunits that associate together along tropomyosin. This can bind calcium ions

What is the advantage of the parallel arrangement of fibers? of the pennate arrangement? the convergent?

Advantage of: a. Parallel arrangement of fibers—Since the fibers run long and parallel to eachother, it is beneficial because the longer and more nearly parallel the muscle fibers are to a muscle's long axis, the more they can shorten; cause large movements and have good endurance (not very strong) b. Pennate arrangement of fibers—pack in a lot of fibers and therefore are very powerful muscles but tire easily c. Convergent arrangement of fibers—allows for maximum force production

Which of the above sources (#59) provides energy to fuel prolonged, submaximal activity?

Aerobic respiration provides energy fuel to prolonged submaximal activity.

How does aging affect the skeleton? At what age (approximately) do the bones of the body typically achieve their greatest density?

Aging effects the skeleton due to a decreased rate of protein synthesis (bones more brittle and less tensile in strength compared to normal collagen levels) and a demineralization of calcium and other minerals from the matrix. At age _____ the bones of the body typically achieve their greatest density.

myosin ATPase

An enzyme that catalyses the hydrolysis of myosin aTP in the presence of actin to form myosin aDP and orthophosphate. This reaction is the immediate source of free energy that drives muscle contraction. In the absence of actin, myosin atpase activity is low and requires calcium ions.

Which of the above sources of ATP (#59) is/are anaerobic? aerobic?

Anaerobic production of ATP=direct phosphorlyation of ADP by CP and glycolusis and lactic acid formation; Aerobic production occurs from Aerobic respiration

Describe the gross anatomy of a muscle, beginning with the myofibrils.

Anatomy of a muscle: a. Myofibrils are rodlike contractile elements that occupy most of the muscle cell volume. Composed of sacromeres arranged end to end, they appear banded and bands of adjacent myofibrils are aligned. They are a complex organell composed of bundles of myofilaments b. A sarcomere is a segment of a myofibril, a contractile unit which is composed of myofilaments made of contractile proteins c. Myofilaments are of two types—thick and thin. Thick filaments contain bundled myosin molecules and the thin contain actin molecules and other proteins. Sliding thin filaments past the thick filaments cause muscle shortening. The elastic filaments maintain the organization of the A band and provide for elastic recoil when mucle contraction ends. d. Muscle fiber (cell) is an elongated multinucleated cell that has a banded or striated appearance. It is surrounded by endomysium and composed of many organells called myofibrils e. A fascicle is a discrete bundle of muscle cells segregated from the rest of the muscle by a connective tissue sheath called a perimysium f. A muscle (organ) consists of hundreds to thousands of muscle cells, plus connective tissue wrappings, blood vessels and nerve fibers. It is covered externally by the epimysium.

Name and describe the process by which long bones grow in thickness/diameter.

Appositional growth is bone growth in thickness/diameter and is necessary for bones to remodel properly therefore continues after interstital growth ceases. It begins as osteoblasts beneath the periosteum form bone matrix in ridges surrounding a periosteal blood vessel. They form bone tissue by secreting osteoid on either side of a BV. Overtime these ridges enlarge and completely surround the BV by fusing together and forming the central canal of a new osteon. The periosteum that lines the central canal becomes endosteum and the periosteum on the outside remains periosteum. Osteoblasts in the endosteum form new lamellae and growth proceeds inward toward the central BV. At the same time, other osteoblasts under the periosteum are beginning the same process so that the bone increases in thickness. As bone tissue forms in at the external surface of the bone, osteoclasts in the endosteum of the medullary cavity engage in bone resorption resulting in an increased size of the medullary cavity (so bone not as heavy and diaphysis remains around same thickness but stronger without becoming heavier)

What causes each of the bands, zones, and lines in a myofibril?

Bands, Zones and line in a myofibril: a. A band: dark region where thin and thick filaments overlap b. I band: light region; form 1 sarcomere to the adjacent sarcomere; only thin filaments c. H zone: Narrow and lighter region within the A band because only thick filaments are there; located in the center of the A band and is only visible in relaxed muscle fibers d. M line: a darker line in the center of the H zone that consists of densely packed proteins that hold the thick filaments in place. e. Z disc/line: a dark line through the I band that marks the end of one sarcomere and the beginning of the next; formed by a dense network of proteins that anchor adjacent sarcomeres together

What tissues make up the embryonic skeleton before the 6th week of development?

Before the 6th week of development fibrous connective tissue and hyaline cartilage tissues make up the embryonic skeleton.

In what part of bone does blood cell production occur?

Blood cell production (hemopoiesis) occurs in the spongy bone. More specifically, it occurs in the red marrow of the diploe and trabaclae of irregular bones (in adults) and in all red marrow in children. In adults blood cell production occurs primarily in the diploe of flat bones (os coax, and proximal epiphysis of long bones)

What is the location of the blood vessels and nerves which supply the skeletal muscle tissue?

Blood vessels and nerves, which supply the muscle tissue are located within a muscle between adjacent fascicles. In general, each muscle is supplied by one nerve, one artery and one or more veins. These structures all enter/exit near the central part of the muscle and branch profusely through its connect tissue sheaths. Each skeletal muscle fiber is supplied with a nerve ending that controls its activity. Skeletal muscle has a rich blood supply because they require high amounts of energy, oxygen and nutrients. Muscle capillaries are the smallest of the body's BV and have many features that accommodate change in muscle length in order to straighten and contract with the muscle.

What is/are the function(s) of bone remodeling?

Bone remodeling is a simultaneous process of bone deposit and bone resorption. It serves as a way for bone renewal and healing and is also important in calcium homeostasis. It is important because in our bones we want healthy collagen fibers and osteiod so it removes the weak bone tissue and replaces it with new. Spongy bone is able to turnover as new a lot faster due to surface area.

Describe the structure and function of bursae and tendon sheaths.

Bursae and Tendonsheaths are not part of a synovial joint but are closely associated with them because they are sacs/bags of synovial fluid that acts as a lubricant. Bursae are fibrous flattened sacs that are lined internally with synovial membrane and filled with synovial fluid; act as a tissue for soft tissue to rub against bony tissue. Tendon sheaths have the same structure as bursae but the sac wraps around the tendon forming a cylinder around it. It is located where tendons have friction from movement against underlying bony tissue.

What is the function of calcitonin? What are the target sites for the action of this hormone? What effect does calcitonin have at its target sites?

Calcitonin is secreted by the thyroid gland when plasma calcium levels rise above normal. This hormone inhibits osteoclasts and therefore stimulates osteoblasts to deposit more calcium crystals, it enhances mineralization of the bone matrix and it targets the kidneys to increase the rate of calcium excretion. The net effect is a decrease in the calcium ion levels in the blood back to the normal range and therefore calcitonin release slows due to negative feedback (more important in children especially who are growing rapidly, and maybe pregnant women)

Describe the general characteristics of cartilage, paying attention to the location of perichondrium, blood vessels & nerves, and chondrocytes as well as to the general composition of the extracellular matrix.

Cartilage is made of a variety of cartilage tissue, which is primarily water thus making it resilliant. It is avascular and surrounded by dense irregular connective tissue called the perichondrium. This resists outward expansion when compressed, and blood vessels that carry nutrients to diffuse to cartilage cells (therefore cartilage cannot be thick). All types of cartilage have chondrocytes (cells), which are encased in small cavities (lacunae) within an extracellular matrix, which has ground substance and fibers. Skeletal cartilages contain all three types of cartilage.

What role does complete tetanus play in voluntary movements?

Complete tetanus is important in voluntary movements because it allows for smooth and sustained contractions without fatiguing the muscle

Which of the above properties (#3) is muscle's most distinguishing, or unique, characteristic?

Contractility is muscle tissue's most distinguishing and unique characteristic because it sets muscles apart from all other tissue types

What structures anchor smooth muscle fibers and transmit the tension they develop?

Dense bodies and intermediate filaments anchor smooth muscle fibers and transmit the tension they develop. The dense bodies anchor into the sarcolema and intracellular where intermediate filaments cris cross; intermediate filaments transfer tension the the dense bodies at the surface of the cell; dense bodies can also interact cell to cell to form sheets. Bundles and sphincters between two smooth muscle cells

What happens to the A band, I band, H zone, and Z discs during contraction? to sarcomere length?

During contraction: a. A band—length is set by the length of the filament therefore these do not change in size but get closer together b. I band—gets smaller c. H zone—gets smaller d. Z disc—get closer together e. Sarcomere length—shortens from z line to z line

What happens to bones during prolonged periods of inactivity? Why do athletes have stronger bones than sedentary people?

During prolonged periods of inactivity (mechanical stress) there is reduced osteoblast activity and therefore a net loss in bone mass and material. Athletes on the other hand, are usually subjected to increased mechanical stress, which stimulates osteoblasts and increases bone production and density. They also may have larger tuberosities because their muscles pull on their bones harder.

What is taking place during the relaxation period?

During the relaxation period tension levels fall due to cross bridge cycling stopping because Ca is pumped back into the SR so not all troponin is bound to Ca and TM covers only the few available active sites. A muscle is considered in relaxation when it is stull pumping Ca ions out and cross bridges are deforming; it is not considered at rest until it is at its normal state and waiting to be stimulated at the tension = 0

muscle power

Each muscle fiber contracts with a certain force, and the strength of the whole muscle is the sum of these muscle fibers. The maximum strength of a human muscle lies between 3 and 4 kg/ m2 of the cross section

Describe the process of endochondral ossification.

Endochondrial Ossification occurs in 6 steps (which do not only occur in long bones): a. Development of a cartilage model: this occurs in the early weeks of embryonic development as mesencymal cells cluster and differentiate into chondroblasts and secrete matrix to make a template. The model is made of avascular hyaline cartilage surrounded by a perichondrium of BV and nutrients. b. Growth of the cartilage model: template grows in length by interstitial growth and diameter by appositional growth. As the chondrocytes grow, they rupture and die increasing the pH of the cartilage matrix and results in beginning of calcification. This persists quickly as positive feedback takes hold and more cells die (due to lack of nutrients) and more cartilage is calcified. Some tissues descintergrate and create air pockets c. Development of the primary ossification center: This primary ossification center is located along the diaphysis of the bone model in the perichondrium where an increase in vascularity triggers mesenchymal cells to become osteogenic cells. Before all cells in perochondrium were chondrocytes but now the perichondrium convert to a periosteum as osteoblasts differentiate and secrete osteoid to form the bone collar. The bone collar is a ring of firm stable bone tissue which stabilizes the diaphysis. This forms after the matrix starts to calcify. d. Invasion of the periosteal bud: is located ___________________________________________. The periosteal bud is a collection of structures atht invaginates into the central cavity containing a nutrient artery, vein, lymph vessels, nerve fibers, osteogenic cells, osteoblasts/clasts, and hematopoetic stem cells. These vessels begin to branch and spread longitudinally as osteoclasts work to hollow out the cavity by phagocytosis of cartilage matrix that remains. Osteoblasts secrete spongy bone on the internal surface of the bone collar; the medullary cavity forms at the ossification center and hematopoetic stem cells form the red marrow. Anything that remains cartilage can technically still grow. e. Development of the secondary ossification center forms at the epiphyses of the bone and with this ossification center, no medullary cavity forms and ossification starts internally and moves outward. Forms at or around the time of birth in most bones of the body. It *At birth babies have: bony diaphysis, growing/widening medullary cavity, and a cartilage epiphysis f. Formation of the articular cartilage and epiphyseal plates: the region between the epiphysis and diaphysis at either end is called the metaphysis. This region contains cartilage that can grow in length after birth (interstitial, stops in adolesence and early 20s). the edges of bones which articulate with other bones do not have periosteum on their outside but rather articular cartilage which is a thin layer atop compact bone which covers the red marrow.

Describe the entire process of excitation-contraction coupling, beginning with a nerve impulse in a motor neuron.

Excitation-Contraction Coupling (EC Coupling) begins with a nerve impulse in a motor neuron HOW GET TO MUSCLE??. The Action potential sweeps along the sarcolema and activates it as it moves down the T tubules causing a voltage change and the release of Ca ions from the terminal cisternae of the SR into the sarcoplasm. Ca ions can leave so quickly because of the large electrochemical gradient between the SR and the sarcoplasm. The calcium binds to troponin which changes shape and pulls tropomyosin away from the active sites on actin. At this point, cross bridge cycling begins and continues in the presence of ATP and calcium. Tension and contraction forces are created through crossbridge cycling. Then, intracellular Ca levels fall as ATP dependent calcium pumps in the SR resequester Ca ions. With less calcium to bind to troponin, it begins to detach from TM and TM slides back over the active sites and cross bridge cycling stops—relaxation occurs but the muscle is not at rest yet until the tension = 0. The excitation signal is shut off by AChE degrading neurotransmitters when Ca is resequestered by being pumped back into the SR

Which of the above properties (#3) are protective?

Extensibility and Elasticity are protective properties of muscle tissues

What factors can affect bone growth, repair and remodeling?

Factors that effect bone growth, repair and remodeling: a. Mechanical stress (compression, bending and gravity) b. Nutrition (sufficient amounts of calcium and phosphorous, and Vitamin A, K, B12, C and D) c. Hormonal regulation of bone growth and development d. Regulation of calcium homeostasis e. Aging

What factors influence the amount of force that a muscle can generate?

Factors that influence the amount of force that a muscle can generate are: a. Degree of muscle stretch (slight stretch is ideal) b. The number of fibers activated (greater motor unit recruitment, greater contractile force) c. The relative size of the muscle (increased size/cross sectional area yields more force—hypertrophy)

Which fiber type has the fastest contraction speed? the slowest?

Fast glycolytic fibers have the fastest contraction speed and slow oxidative fibers have the slowest contraction speed.

Name the CT sheath that surrounds individual muscle fibers. Of what type of CT is this sheath composed?

Fine areolar CT sheaths called endomysium surround individual muscle fibers.

Name and describe the three functional classifications of joints.

Functional classification of joints are based on how much movement is allowed: a. Synarthrosis—immovable (ex. Fibrous joints/skull) b. Amphiarthrosis—slightly movable (ex. Joints between vertebrae) c. Diarthrosis—freely movable joints (ex. Humerous/ulna articulation, knee, hip)

What is the role of ATP and the myosin crossbridge in the sliding filament mechanism?

Functions of ATP and myosin crossbridge in the sliding filament mechanism: a. ATP→binds to myosin head, activates it into the cocked position as ATPase breaks down ATP to ADP and Pi; it must be present for cross bridge cycling to continue; when a new ATP binds to a myosin head after each cycle, it causes the cross bridge to detach from the active site on actin b. Crossbridge formation functions in allowing the filaments to slide past each other as the thick filaments pull on the thin filaments toward the ends of the sarcomeres

What are graded muscle responses? What are the two general ways of producing a graded muscle response?

Graded muscle responses are the varying intensities of normal movements of sustained muscle contractions. It is the ability of a muscle to contract with different amounts of force. The two general ways of producing a graded muscle response are changing the frequency of stimulation or the strength of the stimulus.

What complementary processes are involved in bone remodeling?

In bone remodeling the complementary processes are bone deposit and bone resorption.

Which bones are sites of red blood cells production in children? in adults?

In children RBC production occurs in the red marrow of all bones (spongy), even in the diaphysis and medullary cavity and all parts of long bone. In adults, the red marrow in long bones begins to change to yello marrow and therefore the blood cell production occurs primarily in the diploe of flat bones (os coax, and proximal epiphysis of long bones)

What is the role of Ca2+ and the regulatory proteins in the sliding filament mechanism?

In the sliding filament mechanism, Ca and the regulatory proteins function in controlling the opening and closing of the active sites. If Ca concentration is high in the sarcoplasm then in binds to troponin, which changes the shape of tropomyosin to pull it off of the active sites of actin and allow cross bridge cycling to begin. If there is no Ca to bind to troponin, then tropomyosin remains on the active sites

Describe the difference between an indirect and direct muscle attachment.

Indirect muscle attachment is when the muscle's CT wrappings extend beyond the muscle either as a ropelike tendon or a sheet like aponeurosis. These anchor the muscle to the CT covering of a skeletal element or to the fascia of other muscles. These are more common due to durability and small size. (tendons also conserve space). Direct (fleshy) muscle attachment is when the epimysium of the muscle is fused to the periosteum of bone or pericondrium of a cartilage.

Describe the process of intramembranous ossification.

Intramembranous ossification occurs in four steps: a. Ossification center appears in fibrous CT membrane: mesenchymal cells encurcle BV and differentiate into osteogenic cells which differentiation into osteoblasts which can store minerals. b. Osteoid is secreted within the fibrous membrane by osteoblasts (calcification): the alkaline phosphate in the organic bone matrix contains alkaline phosphatase and collagen fibers. The collagen fibers attract the Calcium. It takes ten days for deposit of CaP to occur in bone, but once present, ossification occurs in 6-10 hours c. Woven bone and periosteum form: forms trabaculae whose plates orient themselves according to the stress lines. Woven bone has no organization and is very random. As it forms the external CT converts to periosteum and osteoblasts gather between CT and bone tissue to form the cell layer of the periosteum. Woven bone is covered by endosteum internally. d. Development of the periosteum and the replacement of woven bone with lamellar bone: Mesenchyme on the outer layer becomes the inner/cell layer of the periosteum. Osteoblasts secrete and develop compact bone on on the inner and outer surface of spongy/flat bones. The BV in the region convert to red marrow and ossification is not fully complete at birth as babies still have fontanelles.

Compare and contrast intramembranous and endochondral ossification.

Intramembranous ossification→the bone develops in the CT template or within fibrous membranes, results in formation of flat bones of skull and it can occur in the dermis (mandible and clavicle) Endochondrial Ossification→ is more significant and is bone formation by replacing hyaline cartilage within the cartilage. This process forms all bones inferior to the skull except the clavicle Both→methods of ossification in humans.

Identify and describe the various types of ligaments associated with synovial joints. Give an example of each.

Ligaments associated with synovial joints a. Intrinsic ligaments (capsular ligaments) located in the fibrous capsule of the joint as thickened bands of dense regular CT (ex. Glenohumeral, iliofemoral) b. Accessory ligaments i. Extracapsular: outside joint capsule (ex. Tibial/fibial collatoral ligaments in knee) ii. Intracapsular: located within the joint capsule, deep to the fibrous capsule and surrpunded by folds of synovial membrane (ex. Cruitat ligaments of knee)

Where is each type of smooth muscle located?

Location of smooth muscle a. Single unit (visceral)→most common; present in walls of hollow organs such as the digestive tract, bladder, arteries and veins b. Multi unit→arrector pili muscle, iris of eye, largest airways and largest arteries (muscle fibers are structurally independent of eachother and innervated by ANS and not self excitatory)

How do long bones grow in length?

Long bones grow in length by a process called interstitial growth. Due to the still metabolically active epiphyseal plate (a catrilagenous region between the epiphysis and diaphysis), bones are able to grow longer at both ends as chondrocytes reproduce and then burst promoting calcification and eventual ossification. As this process occurs this epiphyseal line moves away from the diaphysis allowing the bone to grow in length.

Describe how the following organelles are modified or adapted for function in skeletal muscle tissue: nucleus; mitochondria; smooth endoplasmic reticulum.

Many organelles are modified or adapted for function in skeletal muscle tissue for example: a. Nucleus: muscle fibers (cells) are multinucleated and contain many nuclei just under the sarcolema (plasma membrane); they are not centrally located; important for manufacturing proteins easily b. Mitochondria are sites of oxidative phosphorlyation and ATP production; there are many in the cell because they are used in many steps in contraction therefore there is a high demand for ATP; they lie in rows near contractile proteins of muscle cells c. Smooth endoplasmic reticulum is called the sarcoplasmic reticulum in muscle cells. It regulates the leveles of Ca ions in the sarcoplasm by containing an intracellular fluid with a high concentration of Ca ions compared to the sarcoplasm, which can cause contraction. It completely wraps each myofibril like a sleeve.

Where is most of the cell's ATP produced?

Most of the cell's ATP (95%) is produced in the mitochondria of muscle cells which surround each myofibril during aerobic respiration

What is muscle fatigue?

Muscle fatigue is a state of physiological inability to contract even though the muscle still may be receiving stimuli. It is the decline in ability of a muscle to generate force.

What factors contribute to onset of muscle fatigue?

Muscle fatigue is brought on by Many factors contribute to fatigue but its specific causes are not fully understood. Most experimental evidence indicates that fatigue is due to a problem in excitation-contraction coupling or in rare cases, problems at the NMJ. Availability of ATP declines during contraction but normally it is unusual for a muscle to totally run out of ATP, so ATP Is not a fatigue producing factor in moderate exercise. Iconic imbalances (that disrupt EC coupling) can contribute to muscle fatigue, lactic acid build up contributes to central, not physiological fatigue. Some exercises damage the SR interfering with Ca regulation and release and therefore with muscle activation

Classify each muscle fiber type with respect to its predominant pathway for ATP synthesis, the amount of myoglobin present, and the activity of its myosin ATPase.

Muscle fiber types (predominant ATP synthesis pathway→amount myoglobin→activity of myosin ATPase) a. Slow oxidative fibers/slow twitch/fatigue resistant (SO)→aerobic→high myoglobin→slow ATPase b. Fast oxidative glycolytic fibers/fast twitch/fatigue resistant (FOG)→aerobic→intermediate myoglobin→fast ATPase c. Fast glycolytic fibers/fast twitch/fatigable fibers (FG)→anaerobic glycolysis→low myoglobin→fast ATPase

What is muscle tone, and why is it important?

Muscle tone is sustained and partial contraction in a relaxed skeletal muscle. It is produced when motor neurons spontaneously fire action potentials with no intent of moving so that the muscle is relaxed but partially contracted. It benefits in stabilizing joints, maintaining posture and a higher resting muscle tone makes for a higher resting metabolic rate.

What is the function of myoglobin?

Myoglobin is a pigment similar to hemoglobin in structure but it is only one globin unit with a high affinity for O2. It functions in the transfer of oxygen from blood to mitochondria. Muscle fibers with the most O2 use have the most mitochondria and myoglobin

What is the role of myosin light chain kinase (MLCK)?

Myosin light chain kinases (MLCKs) transfer a phosphate from ATP to myosin cross bridges (activate myosin head); when phosphorlyated can produce a power stroke. MLCK is a slow acting enzyme and therefore cross bridge cycling turns on slowly in smooth muscle and regulates how quickly contraction can occur

In which zone of the epiphyseal plate does ossification occur? Which zone exhibits a high rate of chondrocyte cell division?

Ossification occurs in the osteogenic zone of the epiphyseal plate. The proliferating cartilage exhibits a high rate of chondrocyte cel division.

Describe the cellular structure of osteoclasts. What is the function of these cells?

Osteoclasts do not come from osteogenic cells. They form in the bone marrow thru the fusion of 50+ monocytes to form a multinucleated mass by fusion of cells. They have one surface that is flattened and outlined by a ruffled border. They function in resoprtion and breakdown of the bone matrix. They are found in shallow depressions on inner bone surfaces covered by endosteum.

How do osteoclasts break down bone matrix?

Osteoclasts release lysosomal enzymes on the surface of the bone (contained in 1 place by ruffled border) to digest the bone. Reasons for bone resorption include breaking down to build new healthy bone, bone remodeling and redulation/increase of blood calcium ion levels in the blood (which are stored in the bone matrix). Osteoclasts can also phagocytize anything released besides calcium ions.

What cells secrete osteoid?

Osteoid is secreted by osteoblasts

What is meant by the term oxygen deficit or oxygen debt (which is more correctly called "recovery O2 uptake")?

Oxygen debt is the extra amount of oxygen that the body must take in to compensate for processes that were slowed down during a lack of oxygen in exericese (restorative processes). It represents the difference between the amount of oxygen needed to totally aerobic muscle activity and the amount actually used. All anaerobic sources of ATP used during muscle activity contribute to this deficit, which is better called "recovery O2 uptake"

What is the function of parathyroid hormone? What are the target sites for the action of this hormone? What effect does parathyroid hormone have at its target sites?

Parathyroid Hormon (PTH) functions when blood Calcium levels fall below normal, is breaks down bone to release calcium into the blood supply. PTH targets osteoclasts to resorb/break down bone and release calcium into the blood, it targets the kidneys to decrease the rate of excretion of calcium and increase the rate of reabsorption, and it also targets the kidneys to activate vitamin D which has the indirect effect of increasing the rate of intestinal calcium ion absorption. The net effect of these mechanisms results in blood calcium levels increasing back to their normal range and therefore slowing the release of PTH by negative feedback

What is the most important hormone regulating blood calcium levels and calcium storage in adults?

Parathyroid Hormone is the most important hormone regulating blood calcium levels and calcium storage in adults because it responds to low levels of calcium in the blood (hypocalcemia). More important in adults because adults less likely to have hpyercalcemia and therefore do not need as much calcitonin

Describe the location and function of the perforating (or Volkmann's) canals

Perforating/Volkmann's canals pass through compact bone at right angles to the central canal. The BV and other structures pass through the periosteum, endosteum and into the medullary cavity. Once in the bone they branch to run longitudinally in the central canals.

Identify and describe the physiologic steps involved in the repair of bone fractures.

Physiologic steps in repair of bone fractures: a. Hematoma formation: a blood clot forms at the point of the fracture because the BV in the bone/periosteum tear/rupture and the blood leaks. The clot is formed and stabilized within 6-8 hours of the fracture. The bone tissue near blood clot has cells die and blood releases inflammatory chemicals. The inflammation can occur for several weeks (the macriphages clean up damages/destroyed tissue) b. Fibrocartillaginous callus forms: some cells that invade the fracture site are fibroblasts and secrete CT matrix into the fracture site. This matrix contains collagen which will completely bridge the gap between the two pieces and therefore realignment is important early on. As the matrix forms, fibroblasts become chondrocytes and formation of fibrocartilage matrix at fracture site—this is the callus c. Bony callus forms: and replaces the fibrocartilage callus. Osteoblasts secrete osteiod that becomes trabaculae of spongy bone deposited around the dying fibroblasts producing fibrocartilage. Then eventually, all is bony callus of trabacular bone/woven bone (disorganized) d. Bone remodeling: 3-4 weeks later this begins and can continue for many months. Bony callus is converted to compact bone and extra material is removed from the external area as well as the medullary cavity. There is often a thicker density of bone tissue at a fracture site or a slight bulge.

Identify the primary hormones that regulate bone growth and development. What is the general function of each of the hormones identified?

Primary hormones that regulate bone growth and development: a. Growth Hormone (hGH) and insulin-like growth factors (IGFs): important in childhood and is produced and released by the antipituitary gland; it stimulates IGF by the liver and skeletal system and triggers bone growth and development during childhood b. Thyroid hormones: secreted by the thyroid gland and stimulate cellular metabolism throughout the body and have an especially stimulating effect on osteoblasts c. Sex hormones: released at puberty and specific times from the gonads (estrogen or testosterone/androgens); they are responsible for growth spurts during puberty and adolescence (in cartilage growth plate); form pelvis differently (wider in women and shorter stature because close GP earlier; overcome chondroblast activity and seal growth plate

What prevents prolonged stimulation of the muscle fiber by acetylcholine (ACh)?

Prolonged stimulation of a muscle fiber by ACh is controlled by AChE (acetylcholinesterase) which have high concentration in the synaptic cleft to break down ACh when nervous system activation of that muscle fiber ends

What is recruitment (i.e., multiple motor unit summation)?

Recruitment (multiple motor unit summation) is when changing the number of motor units activated varies the strength of the stimulus. Greater external force is achieved by activating more motor units.

What are the differences between red and yellow marrow?

Red marrow contains hematopoetic stem cells, which form red blood cells, and is located in the medullary cavity of a young person (later only in ends of long bones). Yellow marrow replaces red marrow in the medullary cavity in adolescence and adults and is made of adipose tissue.

What two factors permit relaxation?

Relaxation is permitted by absence of Ca and therefore TM recovers active sites

Describe the relationship between resting length and tension development in smooth muscle.

Resting length and tension development in smooth muscle is different in skeletal muscle in that there is not a most ideal length. It is not a problem if the fibers are stretched too much or are too short in smooth muscle because there are no sarcomeres; therefore the fibers can stretch and still contract forcefully and if they are already semi-shortened they can still contract (2x and .5x normal resting length)

What is the impact on the skeleton of rising levels of sex hormones at puberty?

Rising levels of sex hormones at puberty cause growth spurts in the cartilaginous tissue of the epiphyseal plate (growth plate). Estrogen forms the pelvis wider and also seals growth plates sooner, making women generally shorter.

What are the series elastic elements (SEE) of the muscle and how do they influence force production?

Series elastic elements of the muscle (SEE) are the non-contractile structures of a muscle that must be elastic to allow for shortening and lengthening to occur. When tension develops without shortening, the SEE are tightening because the internal tension must be greater than the resistance for shortening to occur. (dystrophin, titin, CT coverings such as perimyesium, and tendons)

What is the function of Sharpey's fibers?

Sharpey's Fibers function in anchoring the periosteum to the bone matrix. They are composed of strong collagen fibers, which have extentions into the fibrous periosteum. By penetrating and dispersing within the bone, they are also able to distribute mechanical forces over a greater surface of the bone

Relative to muscle function, what is the significance of Sharpey's fibers?

Sharpey's fibers function with muscles because they are a matrix of connective tissue consisting of bundles of strong collagenous fibers connecting periosteum to bone. They are part of the outer fibrous layer of periosteum, entering into the outer circumferential and interstitial lamellae of bone tissue. The tendons of muscles intertwine with these fibers in order to create a strong bond to the bone, which the muscle is responsible for moving via pulling and forceful actions. These are very strong and anchored fibers, which are beneficial when muscles pull on bones so the muscles do not detach.

Describe the general structure of short, flat, & irregular bones.

Short/flat/irregular bones have a thin outercoating of compact bone covered by a periosteum. On the inside, they have spongy bone (good for resorption) covered by endosteum (in flat bones (skull and ribs) the spongy bone=diploe). The trabaculae are always aligned according to stress lines. Due to the amount of spongy bone, they are great shock absorbers and in certain bones the marrow in the diploe is important for RBC production (hemopoiesis)

Describe the process of signal transmission at the neuromuscular junction (i.e., communication of nerve AP to the muscle fiber).

Signal transmission at the neuromuscular junction begins with a nerve impulse (action potential as voltage gated channels open and allow Ca out) triggering ACh to release into the synaptic cleft. Here the electrical signal is converted to a chemical signal. The ACh then diffuses across the synaptic cleft and binds to receptors on the motor end plate. The ACh binds and thus opens ligand-gated Na channels. The Na rushes into the muscle fiber and triggers a muscle action potential that can trigger contraction. It does this as it triggers an electrical impulse in the sarcolema (chemical signal is converted back to electrical when the Na gate opens). When ACh is degraded the impulse stops

Which type of smooth muscle exhibits rhythmicity and self-excitation?

Single unit smooth muscle (visceral) exhibits rhythmicity and self excitation

What is the role of gap junctions and pacemaker cells in single-unit smooth muscle?

Single unit smooth muscle: a. Gap junctions function in connecting adjacent cells and allowing excitation impulses to spread rapidly through the entire sheet so it can contract as a unit b. Pacemaker cells are usually present and set the rhythmic pattern of contraction by spontaneously activating (self exciting) and spreading an impulse through the sheet

Identify and describe the six types of synovial joint. Give an example of each.

Six types of synovial joints: a. Planar joints—gliding joints whose articular surfaces are flat (ex. Sacroilliac joint) b. Hinge joints—concave articulates with convex (socket), monoaxial, movement in one plane (knee and elbow) c. Pivot joints—rotate, the rounded end of one bone articulates with a ring formed by another bone or ligament, monoaxial, (proximal radioulnar joint) d. Condyloid joints (ellipsoid joints)—the oval surface on the end of one bone fits into an oval depression on another, bi-axial (bones rock against eachother) and can measure angles of joints and ROM, (wrist, knuckles) e. Saddle joints—modified condyloid joint in which concave and convex surfaces on each bone fit closlet (complementary joints), biaxial, (thumb) f. Ball and socket joints—angular joint that allows movement in three planes (triaxial), most freely movable synovial joint (shoulder and hip joint)

What gives skeletal muscle fibers a striated appearance?

Skeletal fibers get a striated appearance from the sarcomeres within a myofibril of a myofilament. The sarcomeres are side by side along the entire length of a myofibril and the overlapping arrangement in each myofibril of thick and thin filaments forms striations.

Which fiber type receives the richest blood supply?

Slow oxidative fibers receive the richest blood supply by their dense capillary network (therefore are color red)

How is smooth muscle contraction regulated?

Smooth muscle contraction is regulated through two important proteins (calmodulin and myosin light chain kinase MLCK); calmodulin is activated by binding calcium which activates MLCK which phosphorlyates ATP and activates myosin head; when no Calcium, myosin head cannot activate and no cross bridge cycling

What type of bone makes up the epiphyses?

Spongy bone makes up most of the epiphysis, lined by a thin layer of compact bone

Describe the stress-relaxation response.

Stress relaxation response is special to smooth muscle and it means that when the muscle fibers are stretched/stressed they respond by initially increasing their tension and then they relax a lot. This can be very beneficial such as in the stomach and bladder to accommodate changing volume. It occurs because the cross bridges stay latched longer increasing tension when stretched but when tension gets too great they immediately release cross bridges to relax and accommodate volume or environment

Describe the major structural and functional differences between smooth and skeletal muscle.

Structural and Functional Differences between smooth and skeletal muscle: a. Smooth: i. Structure—smaller in diameter and length; each fiber surrounded by endomyesium that carries BV and nerve fibers but does not become tendons or aponeuroses; ONE centrally located nucleus; thick and thin filaments present but no sarcomeres/striations/myofibrils; no t tubules or terminal cisternae; 10-15 thin filaments per thick filament; able to shorten more; SR irregular and located at some places where contacts sarcolema; thick filaments have cross bridges along whole length; network of dense bodies/intermediate filaments to anchor and transmit tension and form sheets of cells and tissues; neuromuscular junctions unstructured with varicosities (diffuse junctions) ii. Functional—increased sarcoplasmic Ca triggers contraction (most Ca comes from ECF); slow onset and prolonged contraction of smooth muscle; no troponin therefore active sites always open (have calmodulin and MLCK) b. Skeletal i. Structure—larger in diameter and length; fibers surrounded by endomyesium that prolong to form tendons; many nuclei; sarcomeres/striations and myofibrils present; t tubules and terminal cisternae form triad; only 6 thin filaments per one thick filament; cannot shorten as much if not optimal length; structured NMJ ii. Functional—most Ca comes from SR; quick onset and lasts short while; troponin covering active sites of relaxed muscle

Describe the location and general composition of each of the structures found in a typical synovial joint (i.e., articular cartilage, fibrous capsule, synovial membrane, synovial fluid, articular discs, & ligaments).

Structures of a typical synovial joint a. Articular cartilage—thin layer of hyaline cartilage with no pericardium at the articular surfaces of bones, avascular b. Fibrous capsule—the outer layer of the articular/joint capsule made of dense irregular CT, continuous with the periosteum of the bone on each side of the joint c. Synovial membrane—inner layer of the articular/joint capsule and articulates with the articular cartilage but does not cover it. It is made of areolar CT and lots of elastic fibers d. Synovial fluid—secreted by the synovial membrane and is present within the joint capsule; it contains proteins and fluids that were filtered out of surrounding BV and contains macrophages e. Articular discs—menisci; present in the joint as a wedge or pad of fibrocartilage inside the synovial cavity attached to the fibrous capsule and add extra padding to the joint f. Ligaments—bands of dense regular CT that can be intrinsic (within the fibrous capsule of the joint) or accessory ligaments (extracapsular ligaments—outside joint capsule; iintracapsular—within the joint capsule, deep to fibrous capsule)

Name the CT sheath that surrounds a fascicle. Of what type of CT is this sheath composed?

Surrounding each fascicle is a layer of fibrous CT called perimysium

What structures and materials protect the bones in the articulation of a synovial joint?

Synovial fluid, articular cartilage, and ligaments protect the bones in the articulation of a synovial joint by aiding in friction reduction and shock absorption

What are the T tubules? Where are they located?

T tubules are transverse tubules that are tunnel like invaginations of the sarcolema (plasma membrane) that extend into the sarcoplasm at right angles to the cells surface. They completely surround each myofibril with the SR located on either side. The t tubules contain extracellular fluid not sarcoplasm. Therefore, T tubules can carry excitation signals into the muscle cells very quickly. The depolarization/electrical impulse of an action potential spreads along the sarcolema and into T tubules

What is the relationship between the initial length of the sarcomere (or muscle fiber) and the amount of tension it can produce?

Tension production in muscle fibers is dependent on the resting length (how much overlap between thick and thin) of sarcomeres in the muscle before the contraction begins (length-tension relationship). They are able to produce great tension when there is optimal overlap between thin and thick filaments just prior to the onset of contraction. When the muscle is extremely stretched or contracted (sarcomeres already pulled tight or very spread apart) the ability to produce great tension is greatly reduced. The resting length of all muscles in the body is 'near-optimal'

What is the significance of the Ca2+-release channels and the Ca2+ active transport pumps in the SR?

The SR contains many pumps and channels involved with Ca ions that have different functions a. Ca release channels→open when receive a stimulus to let Ca out of the SR and into the sarcoplasm during contraction b. Ca active transport pumps→pump Ca from the sarcoplasm back into the SR when there is no longer a stimulus and the muscles want to relax

Describe the location of the sarcoplasmic reticulum (SR) with respect to the myofibrils.

The SR envelops each myofibril like a sleeve and is located on either side of a T tubule

Why is the triad of functional significance?

The Triad has an important functional significance because it is where a T tubule meets two terminal cisternae. It is important in muscle contractions because this is where the action potential is carried from the exracellular fluid (t tubules) into the intercellular fluid (terminal cisternae). The integral membrane proteins extend from T tubules into the intermembrane space and act as voltage sensors and also there are intergral membrane proteins that go from the terminal cisternae into the intermembrane space and are receptors that regulate the release of Ca from the SR. These proteins are important in registering the voltage change that causes shape change sensed by integral proteins in the terminal cisternae which trigger a release of Ca ions from the SR

What is the function of the Z disc?

The Z disc/line is a dark line which extends through the I band. A single sarcomere extends from one Z disc to the next therefore in marks the boundary between two sarcomeres. It forms a dense network of proteins that anchor adjacent sacromeres together

Explain the all-or-none law as it relates to skeletal muscle fibers and motor units.

The all or none law is demonstrated by a twitch. It is when a single nerve impulse elicits a single contraction even in all of the muscle fibers of a motor unit; all the muscle fibers in that motor unit are stimulated. One action potential in a motor neuron causes one contraction in the whole motor unit. This applies to skeletal muscle fibers and to motor units. The skeletal muscle fibers are either ON (received the signal) or OFF (resting)

What benefit is provided by a lever that operates at a mechanical advantage? at a mechanical disadvantage?

The benefit provided by a lever that operates at a mechanical advantage is power lever, and the advantage is that a lever allows a given effort to move a heavier load or to move a load further and faster than it otherwise could. A small effort used over a large distance can be used to move a large effort over a small distance. If the load is far from the fulcrom and the effort is applied near the fulcrum, the force exerted by the muscle must be greater than the lad to be moved or supported. This lever system operates at mechanical disadvantage and is a speed lever. These levers allow a load to be moved rapidly over a large distance with wide ROM. Effort farther than load from fulcrom = mechanical advantage Effort nearer than load to fulcrom=mechanical disadvantage

What materials make up the organic and the inorganic parts of the bone matrix?

The bone matrix is made of organic and inorganic portions. a. Organic: (osteoid)—composed of ground substance and collagen fibers; makes bones less fragile/brittle by giving tensile strength to resist pulling, twisting , bending and stretching b. Inorganic: consists of mineral salts especially hydroxyapatite (mineral crystals that make up rigid/brittle bone matrix); consists of mostly calcium phosphate which are deposited on collagen fibers and make the bone hard; crystals packed together and allow to resist compression forces applied against bone during weight bearing and support.

What bones make up the appendicular skeleton? How many bones are included in the axial skeleton?

The bones that make up the appendicular skeleton are the bones of the upper and lower extremities and their respective girdles. The appendicular skeleton contains 126 bones total (64 in superior limbs and 62 in inferior limbs)

What bones make up the axial skeleton? How many bones are included in the axial skeleton?

The bones that make up the axial skeleton are the bones of he skill, vertebral column, ribs and sternum (80)

Describe the location and function of the central (or haversian) canals.

The central/haversion canals are at the center of each osteon in compact bone. They run parallel to the long axis of the bone and are lined with endosteum. These structures function in providing a space for the BV, nerves and lymph vessles to run through the bone to supply the osteocytes in lacunae.

Describe the chemical composition of muscle fibers.

The chemical composition of muscle fibers (cells) is 75% water by weight which is attracted and held by proteins; 5% inorganic salts, pigments or substrates and 20% mass from proteins (12% contractile and 8% enzymes or structural proteins)

What type of bone makes up the diaphysis?

The diaphysis is made of compact bone which is thickest in the middle (greatest compression occurs) and thinner toward the ends where it turns into spongy bone

Name the CT sheath that holds bundles of fascicles together to create a muscle. Of what type of CT is this sheath composed?

The epimysium us an overcoat of dense irregular CT that surround the whole muscle but bundling fascicles together.

What is the function of the epiphyseal plate?

The epiphyseal plate functions as the growth plate of long bones which allows both ends of the long bone to continue growing.

Name and describe the four arrangements of fascicles/fibers within skeletal muscles.

The four arrangements of fascicles/fibers within skeletal muscles are as follows. The arrangement of a muscles fascicles determines its ROM and its power. The longer and more nearly parallel the muscle fibers are to a muscle's long axis, the more they can shorten. The greater the number of muscle fibers the greater the power. Stocky bi and multipennate muscles shorten very little but are very powerful because pack in many fibers. a. Circular—when fascicles are arranged in concentric rings; muscles with this arrangement surround body openings, which they close by contracting; sphincters (ex. Orbicularis muscles) b. Covergent—has a broad origin and its fascicles converge toward a single tendon of insertion; triangular or fan shaped (ex. Pectoralis major) c. Parallel—the long axis of the fascicles run parallel to the long axis of the muscle; can be straplike or spindle shaped (fusiform mucles) d. Pennate—the fascicles and thus the muscle fibers are short and attach obliquely to a central tendon that runs the length of the muscle. If the fascicles insert into only one side of the tendon the muscle is unipennate (extensor digitorum longus); if the fascicles insert into the tendon from opposite sides the arrangement is bipennate (rectus femoris); multipennate arrangements look like many feathers sitiated side by side (deltoid muscle)

What are the four basic components of the skeletal system?

The four basic components of the skeletal system are bones, cartilages, ligaments and joints.

Name, describe, and give an example of each of the four categories of bone, classified by shape.

The four categories of bone classified by shape are: a. Long bones→longer than they are wide containing a shaft and two ends, named for elongated shape NOT overall size (all limb bones except patella, and wrist and ankle bones) b. Short bones→cube shaped (the bones of the wrist and ankles); sesamoid bones are a special type of short bone that form within a tendon and some alter the direction of pull of a tendon (kneecap/patella) c. Flat bones→thin, flattened and usually a bit curved (breast bone, scapulae, most skull bones and ribs) d. Irregular bones→complicated shapes that do not fit into a class (vertebrae and hip bones)

Name and describe the four functional characteristics of muscle.

The four functional characteristics of muscles are: a. Excitability (responsiveness/irritability): ability to receive and respond to a stimulus, or any change in the environment inside of outside the body. b. Contractility: the ability to shorten forcibly when adequately stimulated; sets muscles apart from all other tissue types c. Extensibility: ability to be stretched or extended. Muscle cells shorten when contracting but can be stretched beyond resting length when relaxed d. Elasticity: the ability of a muscle cell to recoil and resume its resting length after being stretched

What are the four general functions of the muscular system?

The four general functions of the muscular system are: a. Producing movement—all movements of the human body result from muscle contractions; skeletal is responsible for locomotion and manipulation; smooth is responsible for maintaining blood pressure and working organs and food through GI tract; cardiac muscle is responsible for pumping the blood through the heart b. Maintaining posture and body position—muscles function simultaneously and continuously to counteract the never ending downward pull of gravity c. Stabilizing joints—as muscles pull on bones to cause movements they stabilize and strengthen the joints of the skeleton d. Generating heat—generate heat as they contract which is important in maintaining normal body temperature (mostly due to skeletal muscles which are 40% of body mass)

Identify and describe the four types of cells that form and maintain bone tissue.

The four types of cells that form and maintain bone tissue are a. Osteogenic cells: nonspecialized stem cells from mesenchyme; located in endosteum and inner periosteum and some differentiate into osteoblasts b. Osteoblasts: secrete the fibers of the matrix (collagen), immature, trigger calcification of bone matrix; mature to osteocytes when trappe din lacunae of lamellae c. Osteocytes: mature osteoblasts; lower metabolic rate but maintain bone matrix/tissue by being alive; in lacunae d. Osteoclasts: different from cells a b and c; can break down bone to release Ca into blood (bone resorption), multinucleated from +50 monocytes; found on shallow depressions on inner bone surfaces covered by endosteum and release lysozomal enzymes on surface of bone to digest it (the enzyme is contained within the ruffled border)

What is the general function of spongy bone? of compact bone?

The function of spongy bone is to hold red and yellow marrow in their trabaculae; to undergo resorption quickly (calcium turnover) due to high SA and lighten overall weight of skeleton and bones. The function of compact bone is to provide structure to the body and distribute forces of weight bearing effectively.

What is the function of the SR and terminal cisternae?

The function of the SR is to aid in muscle contraction by regulating levels of Ca ions in the sarcoplasm; the terminal cisternae is the enlarged chambers of SR on either side of a T tubule (the three pieces together make up a triad) It contains intergral proteins that extend from T tubule membrane into terminal cisternae and act as voltage sensors for active potentials spreading across the cell. The integral proteins of terminal cisternae which also extend into the IMS are receptors that regulate the release of Ca from the SR

What is the function of the epiphyses? of the articular cartilage?

The function of the epiphysis is shock absorption, and making RBC in adults in spongy bone. The function of the artucilar cartilage is shock absorption and reducing friction at the articular surfaces (made of hyaline cartilage at articular surfaces of bones)

What is the function of nutrient foramen?

The function of the nutrient foramen is a channel through the periosteum into the bone through which blood vessels, nerves and lymph vessels pass making the bone highly vascularized.

Compare and contrast osteoarthritis (OA), rheumatoid arthritis (RA), and gouty arthritis (i.e., gout).

The functional difference between uniaxial, biaxial and multiaxial joints is seen in the ways in which joints can/cannot move. Uniaxial can move in one plane, biaxial can move in two planes, etc.

Identify the functions of the skeletal system.

The functions of the skeletal system are: a. Support→frame work for body and cradles soft organs b. Protection→ribs protect thorax, vertebrae protect spinal cord and skull protects brain c. Movement→skeletal muscles which attach to bones by tendons use bones as levers to move the body and its parts d. Mineral and growth factor storage→bone is a reservoir for minerals (calcium and phosphate) and growth factors (ex. Insulin like and transforming) e. Blood cell formation→hematopoesis occurs in the marrow cavities in certain bones f. Triglyceride (fat)storage→stored in bone cavities and is a source of stored energy for body

What is the latent period and what is taking place during the latent period?

The latent period of a twitch is when a stimulus has been applied but there is no external force production for a short time. During this time the muscle is waiting for the action potential to be carried across the sarcolema and down the T tubules, Ca from the SR to be released, troponin to bind to Ca and pull TM off of the active sites→then cross bridge cycling beings with the first movement; the voltage or # of muscle fibers activated to produce a muscular response (twitch)is the threshold stimulus.

Describe the medullary cavity (i.e., where is it located? what structures are found there?).

The medullary cavity is located within the diaphysis of a long bone. It is lined by spongy bone, which is covered by endosteum. In this cavity, RBC production occurs for newborns and as one ages, the red marrow converts to yellow marrow (adipose)

Where is the metaphysis? What is the functional significance of this part of the bone?

The metaphysis is between the diaphysis and epiphysis on either end of the bone. It is important because it contains the growth plate/epiphyseal line which allows long bones to grow longitudinally in length (interstitial growth)

Describe the microscopic structure of compact bone, paying attention to the location of the lamellae, lacunae, osteocytes and canaliculi.

The microscopic structure of a compact bone consists of structural units called osteons/haversion systems. These osteons have several components. They are organized around a central/haversion canal, which runs parallel to the long axis of the bone and is lined with endosteum. This canal contains the BV, nerves and lymph vessels that supply the bone. The lamellae are the concentric circles made of matrix materials that surround the central canal and make up the osteon. The collagen fibers in adjacent lamellae are oriented in different directions, and since the hydroxyapetite crystals run parallel to the collagen fibers, they also are oriented in different directions in each lamellae. The canaliculi are small openings that connect the lacunae (which hold osteocytes and lie between adjacent lamellae) to each other and to the central canal. This is how the osteocytes communicate. Interstitial lamellas are between osteons filling the gaps and circumferential lamellae make up the outer ring that encircles the whole diaphysis.

Compare and contrast the microscopic structure of compact and spongy bone.

The microscopic structure of spongy bone does not contain osteons. It has trabaculae which allow for quick bone resorption. Osteoclasts are more abundant in spongy bone. It contains nutrient blood vessels but they are much less organized because there is no central canal. There is an endosteum that lines the inside of the spongy bone. Lamellae make up the trabeculae in irregular arrangements and are therefore considered interstitial because there is no central canal or concentric rings.

What is the most common lever system in the in the body? Where is the fulcrum with respect to the load and effort in this lever system?

The most common lever system in the body is third class lever systems. In these, the effort is applied between the load and the fulcrum. These are speedy and always operate at a mechanical disadvantage. An example in the activity of the biceps muscle of the arm, lifting the distal forearm and anything carried in the hand. Third class muscle systems allow a muscle to be inserted very close to the joint across which movement occurs which allows rapid extensive movements with little shortening of the muscle (which tend to be thicker and more powerful).

What type of tension is developed most efficiently (i.e., requires less ATP expenditure per unit of work accomplished)? least efficiently?

The most efficient tension is eccentric and the least efficient is concentric. This is because eccentric requires less ATP expenditure per unit of work accomplished because an outside force is doing the word where as in concentric contractions external work is done and the contracting muscle is responsible for ALL the work being done, using more ATP

What is the most prevalent chemical compound (by weight) in muscle?

The most prevalent chemical compound by weight in a muscle is H2O

What specializations of the muscle fiber (at the motor end plate) enable it to respond to signals from the motor neuron?

The muscle fiber is specialized at the motor end plate to enable it to respond to signals from the motor neuron by infolding to increase the surface area of the sarcolema at that specific place. More surface area allows more neurotransmitter receptors to attach and thus respond better and more efficiently to the signals of the motor neuron

Name and describe the muscle fiber's three avenues of ATP production.

The muscle fiber's three avenues of ATP production are: a. Direct phosphorlyation of ADP by creatine phosphate i. In exercise, the demand for ATP rises and ATP stored in muscles is used quickly. Creatine Phosphate (CP) is a high energy molecule that is stored in muscles and is tapped to regenerate ATP while the metabolic pathways are adjusting to the suddenly higher demand for ATP ii. CP + ADP→creatine + ATP (very efficient; cells store more CP than ATP); reaction reversible during rest to keep CP levels high iii. Maximum muscle power for 14-16 seconds b. Anerobic glycolysis which converts glucose to lactic acid i. Occurs once ATP and CP are used up ii. Generated from the breakdown of glycogen stored in the muscle iii. Breaks down glucose to 2 pyruvic acid molecules generating 2 ATP per glucose molecule iv. In vigerous exercise, most of the pyruvic acid is converted to lactic acid due to lack of oxygen in peripherial blood vessles; liver cells can reconvert lactic acid to pyruvic acid back to the blood stream or back to glycogen v. Only get 5% as much ATP from each glucose as with aerobic respiration but is 2.5 times faster in generating the ATP vi. Used when need large amounts of ATP for moderate periods (30-40 sec_ c. Aerobic respiration i. During rest and light to moderate exercise (even if prolonged), 95% of the ATP used for muscle activity comes from aerobic respiration. It occurs in the mitochondria and requires oxygen and involves a sequence of chemical reactions in which the bonds of fuel are broken and energy released is used to make ATP. Glucose is broken down entirely to water CO2 and ATP (32 per glucose) ii. Glycogen is first source of fuel and after bloodborne glucose and pyruvic acid from glycolysis and free fatty acids iii. High yield of ATP but slow due to many steps, and requires continuous delivery of O2 and nutrient fuels to keep it going.

Which myofibril structures or regions change length during the contraction process?

The myofibril structures/regions that change length during contraction are the elastic fibers (titin) and the sarcomere

Muscle contraction is currently best described by the sliding filament theory. Why is this name appropriate for the contraction process?

The name 'sliding filament theory' best describes muscle contraction because the thick and thin filaments do not change in length; the myofilaments attach to one another and shorten all other structures of the muscle (sarcomere, muscle fibers and muscle) by sliding past one another.

Which materials are primarily responsible for the tensile strength (i.e., ability to resist stretching forces between its ends) of bone? for the compression strength of bone? Which of these materials makes bone hard and heavy?

The organic portion of bone matrix (namely the collagen fibers) is responsible for the tensile strength of bone (ability to resist stretching forces between its ends). The inorganic portion is responsible for the compression strength of bone, and the calcium salts within the inorganic portion make the bone hard and heavy as it forms compact bone by tightly bound crystals

Name the organic portion of bone matrix.

The organic portion of bone matrix is osteoid (secreted by osteoblasts)

Describe the structure and function(s) of the periosteum.

The periosteum is the vascularized, outer (double) membrane that covers the outside of a bone excepts at its articular surfaces. It is composed of an outer layer of dense irregular CT (fibrous layer) and an inner layer that contains osteoblasts and osteoclasts (osteogenic layer) where bone tissue can be made. It is anchored to the bone matrix by sharpey's fibers

At what point (#44) does the power stroke occur?

The power stroke occurs when myosin attaches to the active site and ADP and Pi are released from the myosin head. This causes a shape change and the head connects to the active side causing the head to rotate toward the sarcomere performing the power stroke. The myosin head pivots as it moves from a high energy to a low energy configuration

Where are the primary centers of ossification typically located? the secondary centers of ossification?

The primary centers of ossification are typically located where there is increased vascularization along the periosteum of the diaphysis of the long bone. The secondary centers of ossification are located within the epiphysis of bones.

What are the primary minerals stored by the bones?

The primary minerals stored by the bones are calcium phosphate crystals (calcium and phosphorous)

What is the refractory period? Why is it significant?

The refractory period is also the contraction period (the point when the graph begins to increase). This is when external force production becomes measurable. Cross bridge cycling occurs and tension production increases as sarcomeres shorten. This phase can last 10msec-100msec depending on whether it is a fast(eyes)or slow (gastrocnemius) twitch fiber; here, maximal tension is produced

Identify the regulatory protein in smooth muscle which binds to Ca2+ to activate the contraction process.

The regulatory protein in smooth muscle which binds to Ca to activate the contraction process is calmodulin

How does the size of a motor unit influence the strength of contraction and the control of a movement?

The size of a motor unit influences the strength of contraction and the control of a movement in various ways: (the size of the motor unit varies based on how many muscle fibers are in the unit) a. Small motor units: deal with fine motor control, function against weaker tension and contain muscle fibers smaller in diameter and are activated first. b. Larger motor units: activated by stronger stimuli and later than small motor units; they are less precise and exert more force; required in weight training preferentially

What are the sources of the sarcoplasmic Ca2+ which triggers smooth muscle contraction? Which of these is the main source?

The sources of sarcoplasmic Ca which trigger smooth muscle contraction are from the extra cellular fluid (main source) and some from the sarcoplasmic reticulum

What factors influence the stability and movement capability (ROM) of a synovial joint?

The stability and movement capability (ROM) of a synovial joint is affected by the shape of bones that articulate, the strength and length of joint ligaments and the arrangement, degree of tone and size of muscles at the joint (too much muscle mass at a joint can impede ROM)

What is the synaptic cleft?

The synaptic cleft is the space between the motor neuron and the muscle fiber where ACh is released across

What is the function of the T tubules?

The t tubules contain extracellular fluid not sarcoplasm. Therefore, T tubules can carry excitation signals into the muscle cells very quickly. The depolarization/electrical impulse of an action potential spreads along the sarcolema and into T tubules

Compare and contrast the three types of skeletal cartilage. Thinking about where each type of cartilage is located in the body, describe how the structure of each type supports its function.

The three types of skeletal cartilage are: a. Hyaline cartilages: provide support, flexibility and resilliance; most abundant; matrix contains only fine collagen fibers and spherical cells. In the body hyaline cartilage is located: articular cartilage, costal cartilage, respiratory cartilage (larynx) and nasal cartilage (external nose) b. Elastic cartilages: look like hyaline cartilage but contain elastic fibers to withstand repeated bending; found only in the external ear and epiglottis c. Fibrocartilages: highly compressable and have high tensile strength (intermediate between hyaline and elastic); formed by parallel rows of chondrocytes alternating with thick collagen fibers; located where there is heavy pressure and stretching such as menisci of knee and discs between vertebrae

How do the trabeculae of spongy bone respond to changes in the patterns of stress to which the bone is exposed?

The trabaculae of spongy bone always change to align themselves in the patterns of stress that that particular bone is exposed to.

Identify and describe the two mechanisms of cartilage growth.

The two mechanisms of cartilage growth are appositional growth and interstitial growth. a. Appositional growth: cartilage forming cells in the surrounding perichondrium secrete new matrix against the external face of the existing cartilage tissue b. Interstitial growth: the lacunae bound chondrocytes divide and secrete new matrix, expanding the cartilage from within

Identify the two primary types of myofilaments found in myofibrils.

The two primary types of myofilaments found in myofibrils are actin (thin) and myosin (thick)

What are the two types of smooth muscle?

The two types of smooth muscle are single unit smooth muscle (visceral) and multi unit smooth muscle

Describe the zones into which chondrocytes are organized within the epiphyseal plate.

The zone of chondrocytes in the epiphyseal plate are those in the: a. resting phase—closest to the epiphysis, and anchors growth plate to epiphysis, cartilage cells rest b. proliferating cartilage—adjacent to the resting cartilage (quiescent), in this phase the chondrocytes are enlarged and undergoing rapid mitosis. The epiphyseal plate is pushed further and further from the diaphysis c. hypertrophic/calcified cartilage—older cells enlarge more and more and eventually rupture (increasing the pH) and allowing for the calcification of the matrix, at this point there are few living chondrocytes left, but it is still not considered bone d. osteogenic zone (closets to the diaphysis)—where new bone tissue forms as the tissues come in contact with osteoblasts (secrete organic part of matrix) and osteoclasts. After ossification occurs there is no linear growth in that area of the bone. The bone continues to grow in length because ossification and mitosis occur at the same rate thus keeping the growth plate the same thickness

Identify the proteins which make up thin filaments.

Thin filaments are made of mostly actin (contractile), but also nebulin (structural), tropomyosin (regulatory) and troponin (regulatory)

Three general types of movements are possible at synovial joints: gliding movements, angular movements, and rotational movements. Describe each type of movement and give at least one example of a joint at which this type of movement occurs.

Three general types of movement possible at a synovial joint: a. Gliding→linear motion in which bones slip and slide past each other, occurs in flat bone surfaces that articulate together, not a planar movement because there is no rotation around an axis (ex. Sacroiliac joints, intercarpal/tarsal, vertebralcostal) b. Angular movements→occur at hinge joints and can measure ROM at these joints, monoaxial (ex. Knee, elbow, ankle, interphalangeal joints) c. Rotation→occurs at pivot joints, monoaxial rotation (ex. Between atlas and axis, proximal radioulnar joint (pronation and supination)

Name and describe the three structural classifications of joints.

Three structural classifications of joints are based on the type of CT that binds the joint and if there is a cavity or not a. Fibrous joints—articulating bones come in close contact with one another and are attached by thin bands of dense fibrous CT; no joint cavity; most are immovable( synarthrosis) or slightly movable but depends on length of CT bands b. Cartilaginous joints—amphiarthrosis, no joint cavity, connecting material between articulating bones is either hyaline cartilage or fibrocartilage c. Synovial joints—diarthrotic joints that are unique because they have a joint cavity filled with synovial fluid to reduce friction; the movement at joints is determined by the structure but all are freely moveable

Name and describe the three types of fibrous joints. Give an example of each.

Three types of fibrous joints: a. Suture—only occur between the bones of the skull and during development change from a fontanel to a synostisis (at adult hood) (sutures form at 1 year of life) ex. Metapoic suture in frontal bone and the epiphyseal line b. Syndesmosis—fibrous joint; If band or cordlike CT=ligament; if sheet=interosseous membrane (amphiarthrosis) movement determined by length of CT. (ex. Between tibia and fibula and between radius and ulna) c. Gomphosis—articulation between tooth and alveolar socket in jaw (tooth held in position by periodontal ligament and should be an immovable joint—if inflammation then movement can occur, which is undesirable)

Which of the proteins identified above (#29) is/are regulatory proteins?

Tropomyosin and troponin are the regulatory proteins of actin

Which protein covers the active sites on the actin filament in a resting muscle fiber?

Tropomyosin is the protein that covers the active sites on the actin filaments in a resting muscle fiber.

Specifically, how do troponin and tropomyosin help regulate the contraction process?

Troponin and Tropomyosin regulate the contraction process by controlling the active sites on actin that bind myosin and therefore result in tension production. When a muscle is contracting, troponin is pulling TM off of the active sites but then a muscle is no longer receiving a stimulus and wishes to relax, troponin releases TM to fall back over the active sites and discontinue cross bridge attachment between actin and myosin, thus eliminating tension and contraction

Identify and describe the location of the hyaline cartilage structures that remain when secondary ossification is complete.

Two hyaline cartilage structures remain after secondary ossification is complete. One is the articular cartilage which lines the ends of long bones at the epiphyses to reduce friction and provide cushion for shock. The other is located in the growth plate of the metaphysis. This cartilage remains and undergoes interstitial growth to make the long bones grow in length after birth until around the age of 20.

Name and describe the two types of cartilaginous joints. Give an example of each.

Two types of cartilaginous joints: a. Synchondrosis—articulating bones connected by hyaline cartilage (synarthroses/immoveable); temporary not permanent articulations. (ex. Epiphyseal plates, and first rib→manubrium articulation (replaced with bony/somewhat fibrous joint (synostosis)). b. Symphysis—articular surfaces are covered with hyaline cartilage (articular) which is fused to a disc/pad or fibrocartilage between the bones—amphiarthrosis (ex. Pubis symphisis and intervertevral disks) good for compression, shock absorption

Identify and compare the two types of indirect muscle attachments.

Two types of indirect muscle attachments are tendons and aponeurosis. Tendons are a tough band of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension. It is ropelike in shape and connects the muscle to a skeletal element of the fascia of other muscles. Aponeuroses are sheetlike extentions of the muscles CT wrappings, which anchor the muscle to the fascia of other muscles or to a skeletal element.

Compare and contrast the physical exam findings for a person with osteoarthritis or rheumatoid arthritis of the knee. It may be helpful to draw a table with two columns, and consider factors such as pain, morphology of the joint, skin changes, bilateral or unilateral, crepitus, mobility, etc.

Types of arthritis: a. Osteoarthritis (OA): most common with aging women due to wear and tear on joints, enzymes destruct cartilage to the point where they become dry and cracked and friction causes pain and stiffness, bones inflame and enlarge b. Rheumatoid arthritis (RA): autoimmune disease common in 40-50 year old women, not as common as OA but more destructive, can be triggered by bacterial or viral infection, S/S are tenderness and sstiffness of joints, affects batient bilaterally always, synovial membrane thickens and swells releasing more synovial fluid, (cartilage not affected first), overtime this fluid adheres to the articular cartilage and destroys it. The articular cartilage tries to repair itself and scarring occurs which fuses bones and therefore there is no movement at the joint (scaring and fusing = ankalasois which results in bent, stiff, immovable joints), destruction occurs during periods of active inflammation (flares) and not during calms therefore the course is variable. It is treated by trying to limit inflammation with steroids and anti-inflammatory drugs c. Gouty arthritis: more common in men due to their higher levels of blood UA than women. It is caused by an accumulation of uric acid at a joint. Uric acid is the metabolic by product of nucleic acids and is normall removed from the blood when filtered through the kidneys and excreted out in urine. If blood uric acid levels rise, UA is deposited as crystals in joint. It can accumulate because of over production or under excretion. It is first deposited at the base of the big toe and if not treated can damage the cartilage at a joint. To treat in less severe cases, limit alcohol and red meat.

What is the difference between unfused tetanus and complete tetanus? How is complete tetanus achieved in a muscle fiber?

Unfused tetanus occurs when there is frequent stimulation and the muscle is not allowed to relax completely between them. The tension reaches a peak but vacillating level. Complete tetanus is when stimulation occurs so frequently that relaxation is eliminated all together, resulting in a smooth continuous contraction with no evidence of relaxation. This is achieved in a muscle fiber by rapid and continuous stimuli (in humans not in all muscle fibers—stimulate different motor units so not all contracting at same time and don't fatigue muscle)

How does vitamin C influence bone structure?

Vitamin C influences bone structure because it is required for osteoid secretion because it is used to make collagen fibers (deficiency can lead to rickets in kids)

How does vitamin D influence bone structure?

Vitamin D influences bone structure by aiding in calcium absorption when activated. If there is no vitamin D, there cannot be absorption of calcium ions and therefore bones are soft and weak. This may result in rickets in children and osteomalacia in adults.

What type of tension does a muscle develop when it is acting as an agonist?

When a muscle is acting as an agonist it develops concentric OR external tension.

Describe the relative positions of actin and myosin when the muscle is at its optimal length for strength production.

When a muscle is at its optimal length for strength production actin is just overlapping with myosin. This way it can still contract a great distance as myosin pulls actin inward, but the two myofilaments are not so far apart that they cannot form cross bridges.

What happens to force production in a muscle that is in extreme stretch or contraction?

When a muscle is in extreme stretch or contraction its abilty to produce tension and force is greatly reduced (ex. Hip extenders have a less than optimal length ex. Jumping)

What type of tension is being produced when internal tension is being developed, but no movement occurs?

When internal tension is being developed but no movement occurs the muscle has internal tension/isometric contraction

What is the significance of epiphyseal plate closure?

When the epiphyseal plate closes, the bone can no longer grow in length in that region. This occurs when ossification overtake the rate of cartilage proliferation and the diaphysis fuses to the epiphysis forming the epiphyseal line. The GP in each bone close at different times but the Distal close later than the proximal and they close earlier in girls than boys and at 25 years old all have closed, but can determine for sure by X-Ray

Physiologically speaking, what is the value of ATP's high-energy phosphate bonds?

When the high energy phosphate bond breaks it releases a lot of energy to the cell that is important in the contraction process

What type of tension is being produced when the overall length of the muscle is increasing while the muscle is functioning?

When the overall length of the muscle is increasing while the muscle is functioning the muscle is producing an eccentric contraction/ tension

What happens to pyruvic acid when there is not enough O2 present to completely catabolize it?

When there is not enough oxygen present to completely catabolize pyruvic acid it is converted to lactic acid which is released into the blood

What happens to the strength of contraction when two or more identical stimuli are delivered to the muscle in rapid succession (i.e., before complete relaxation occurs)? What is this phenomenon called?

When two or more identical stimuli are delivered to the muscle in rapid succession (before complete relaxation occurs) each subsequent contraction is greater than the previous. This is called wave summation or incomplete tetanus.

phosphorylation

a chemical reaction in which a phosphate molecule is added to a molecule; ADP becomes ATP

meniscus

a crescent-shaped fibrocartilaginous structure that, in contrast to articular disks, only partly divides a joint cavity. It usually refers to either of two specific parts of cartilage of the knee: The lateral and medial menisci. Both are cartilaginous tissues that provide structural integrity to the knee when it undergoes tension and torsion.

intermediate filament

a family of related proteins that share common structural and sequence features; average diameter of 10 nanometers, initially designated 'intermediate' because their average diameter is between those of narrower microfilaments (actin) and wider myosin filaments.Most types of intermediate filaments are cytoplasmic, but one type, the lamins, are nuclear.

action potential

a large transient depolarization event, including polarity reversal, that is conducted along the membrane of a muscle cell or a nerve fiber

deep fascia

a layer of fascia which can surround individual muscles, and divide groups of muscles into compartments. The high density of collagen fibers is what gives the deep fascia its strength and integrity. The amount of elastin fiber determines how much extensibility and resilience it will have.

synergist

a muscle that aids the action of a prime mover by effecting the same movement or by stabilizing joints across which the prime mover acts, preventing undesirable movements

gap junctions

a passageway between two adjacent cells; formed by transmembrane proteins called connexons

lacuna

a small space, cavity or depression; in bone and cartilage are occupied by cells

synostosis

an abnormal fusion of a joint into a bony joint that is present usually in adults when some sutures ossify and make a bone joint that is not much like CT anymore

origin (of a muscle)

attachment of a muscle that remains relatively fixed during muscular contraction

hemopoiesis

blood cell formation in bones

glycolysis

breakdown of glucose to pyruvic acid—anaerobic process

neurotransmitter

chemical messenger released by neurons that may, upon binding to receptors of neurons or effector cells, stimulate or inhibit those neurons or effector cells

acetylcholine (ACh)

chemical transmitter substance released by some nerve endings

creatine phosphate (CP)

compound that serves as an alternative energy source for muscle tissue (CP)

endosteum

connective tissue membrane covering internal bone surfaces

periosteal bone collar

cuff of periosteal bone that forms around the diaphysis of the hyaline cartilage model in developing long bone

sarcoplasm

cytoplasm in muscle cells

osteoporosis

decreased density and strength of bone resulting from a gradual decrease in the rate of bone formation

Which of the above sources (#59) provides energy to fuel brief, high intensity activity?

direct phosphorlyation of ADP by CP provides energy for brief high intensity activity between 10-20 seconds. Glycolusis and lactic acid formation provide energy for brief high intensity activity after CP is used (20 sec) until about a minute (30-40 seconds)

luxation

dislocation; articulating bones are displaced from normal alignment, the joint does not function and there is no movement, it is associated with spraining and inflammation of joint; if dislocation is total and there is no contact between articular surfaces the luxation is a dislocation

diaphysis

elongated shaft of a long bone

myoblast

embryonic mesoderm cells from which all muscle fibers develop

acetylcholinesterase (AChE)

enzyme present at the NMJ and synapses that degrades ACh and terminates its action

creatine kinase

enzyme that catalyzes the transfer of phosphate from CP to ADP, forming creatine and ATP; important in muscle contraction

aponeurosis

fibrous or membranous sheet connecting a muscle and the part it moves

epiphyseal line

forms when the epiphyseal plate closes and is ossified (a plate of hyaline cartilage at the junction of the diaphysis and epiphysis that provides for growth in length of the bone)

appositional growth

growth accomplished (usually in width) by the addition of new layers onto those already formed

hypercalcemia

high levels of calcium ions in the blood that result in fatigue, confusion, muscle weakness, cardiac arythmia and heart attack

alkaline phosphatase

hydrolase enzyme that removes phosphate groups from enzymes; elevated ALP indicates that there could be active bone formation occurring as ALP is a byproduct of osteoblast activity

interstitial lamella

incomplete lamella that lie between intact osteon, filing the gaps between forming osteons, or representing the remnants of an osteon that has been cut through by bone remodeling

bursitis

inflammation of a bursae, common in knees, elbows and bunions; due to repetitive motion, external pressure, infection or trauma; healed by removing offending factor and using anti-inflammatory, can also apirate the fluid from the sac if it is very bothersome

circumferential lamella

lamella that encircle the whole width/all the way around the bone in its circumference

hypocalcemia

low levels of calcium ions in the blood that result in twitches, spasms, numbness, tingling, cardiac arythmia and respiratory distress

insertion (of a muscle)

movable attachment of a muscle

prime mover (agonist)

muscle that bears the major responsibility for effecting a particular movement

antagonist

muscle that reverses or opposes the action of another muscle

hydroxapatite

naturally occurring mineral form of calcium apatite. up to 50% of bone is made up of a modified form of the inorganic mineral hydroxylapatite (known as bone mineral).

axon

neuron process that carries impulses away from the nerve cell body; efferent process; the conducting portion of a nerve cell

avascular

not vascularized; no blood vessles pass through the tissue

sarcolemma

plasma membrane of a muscle cell

hydrolysis

process in which water is used to split a molecule into smaller particles

bone remodeling

process involving bone formation and destruction in response to hormonal and mechanical factors

oxidative phosphorylation

process of ATP synthesis during which an inorganic phosphate group is attached to ADP; occurs via the ETC within the mitochondria

recruitment

progressive activation of a muscle by successive recruitment of contractile units (motor units) to accomplish increasing gradations of contractile strength.

reduction (of fracture)

realignment of a broken bone/the first step in treatment; should be done as soon as possible; if open fracture it is done through surgery if a closed fracture it is done manually

syncytium

refer to cells that are connected by specialized membrane proteins (e.g. gap junctions), like the heart muscle cells.

osteomalacia

results from a vitamin D deficiency in adults; soft bones and precursor to osteopenia and osteoperosis

rickets

results from a vitamin D deficiency in children when bones bend and the pelvis, ribs and skull become deformed, the ends of the long bones enlarge due to weight bearing

dense bodies

round, amorphous bodies scattered through the cytoplasm of smooth muscle fibers; they appear to be points of attachment for myofilaments

Classify the three types of muscle tissue (according to location, appearance, and type of nervous system control).

skeletal-striated, voluntary. smooth- nonstriated, involuntary, cardiac muscle- striated, involuntary

synaptic vesicles

small membraneous sacs containing neurotransmitter

osteon

system of interconnecting canals in the microscopic structure of adult compact bone; unit of bone also called the haversion system

tendinitis

tenosynovitis; inflammation of the tendon sheaths which can spread to the tendons and synovial membranes; due to overuse, trauma, and external pressure on joint area; it is common in the wrist, ankles, feet and elbows

muscle endurance

the ability of a muscle or group of muscles to sustain repeated contractions against a resistance for an extended period of time.

axon terminals

the bulbous distal endings of the terminal branches of an axon

pacemaker cells

the cells that create these rhythmical impulses and directly control the heart rate

periosteum

the connective tissue membrane covering the external bone surface except the articular cartilage

epiphysis

the end region of a lone bone, which is attached to the shaft and adjacent to the metaphysis

belly (of a muscle)

the fleshy, central bulging portion of a muscle

diploë

the internal layer of spongy bone in flat bones

osteogenesis

the process of bone formation also called ossification

ossification

the process of bone formation also called osteogenesis

metaphysis

the region on a long bone between the epiphysis and diaphysis on each end that contains the growth plate on the long bone

bone resorption

the removal of osseous tissue; part of the continuous bone remodeling process

maximal stimulus

the strongest stimulus that produces increased muscle contractile force; stimulus strong enough to evoke a maximal response

triad

the structure formed by a T tubule with a sarcoplasmic reticulum (SR) known as the terminal cisterna on either side. Each skeletal muscle fiber has many thousands of triads, visible in muscle fibers that have been sectioned longitudinally. Form the anatomical basis of excitation-contraction coupling, whereby a stimulus excites the muscle and causes it to contract.

osteoid

unmineralized bone matrix (organic) secreted by osteoblasts

graded responses

variations in the degree of muscle contraction by changing either the frequency or strength of the stimulus

threshold stimulus

weakest stimulus capable of producing a response in an irritable tissue

sprain

when a joint is twisted in an abnormal/exaggerated way to the point where it stretches and tears ligaments and CT that hold the joint in place, it does not dislocate the bone. They heal slowly because the dense regular CT ligaments are avascular, if torn or shredded completely must have surgery (not the same as strain, which is trauma that tears the connective tissues associated with muscles (tendons)).

subluxation

when the dislocation maintains some contact betweet articular surfaces but is not at all functional