p.11
Neuromuscular Junction and Muscle Contraction
What is the mechanism of muscle relaxation involving Ca²⁺?
Ca²⁺ moves back into the sarcoplasmic reticulum by active transport, requiring ATP.
p.38
Bone Development and Growth
What do fibroblasts produce?
Collagen and granulation tissue.
p.36
Bone Development and Growth
What is formed as a result of appositional growth by osteoblasts?
A new concentric lamella.
p.17
Properties of Smooth Muscle
What is a key difference in myosin attachment to actin between smooth and skeletal muscle?
Myosin remains attached to actin longer in smooth muscle.
p.18
Properties of Smooth Muscle
What is a key difference between smooth muscle and skeletal muscle in terms of neuromuscular junctions?
Smooth muscle has no neuromuscular junctions like in skeletal muscle.
p.32
Structure of Skeletal Muscle
What are the two layers of the periosteum?
The outer fibrous layer and the inner layer of bone cells.
p.32
Structure of Skeletal Muscle
What types of cells are found in the inner layer of the periosteum?
Osteoblasts, osteoclasts, and osteochondral progenitor cells.
p.32
Structure of Skeletal Muscle
What are Sharpey's fibers?
Periosteal fibers that penetrate into the bone to strengthen tendon attachment.
p.18
Properties of Smooth Muscle
What is the function of myosin phosphatase in smooth muscle relaxation?
It removes phosphate from the myosin head.
p.23
Neuromuscular Junction and Muscle Contraction
What effect does Isoproterenol have on intracellular Ca2+ levels?
It increases the amount of intracellular Ca2+.
p.6
Structure of Skeletal Muscle
What is the function of Nebulin in the thin filament?
To serve as a ruler to gauge the length of the F-actin filament during assembly.
p.38
Bone Development and Growth
What stabilizes the two pieces of bone during healing?
The bone/cartilage collar.
p.6
Structure of Skeletal Muscle
What are the components of myosin structure?
Two heavy chains and four light chains.
p.38
Bone Development and Growth
What is the process of bone remodeling?
Replacement of spongy bone and damaged material by compact bone.
p.17
Properties of Smooth Muscle
How does the maximum force of contraction in smooth muscle compare to skeletal muscle?
The maximum force of contraction is usually greater in smooth muscle.
p.14
Muscle Twitch and Motor Units
When does the Treppe effect occur?
In muscle that has rested for a prolonged period of time.
p.12
Muscle Twitch and Motor Units
What is a motor unit?
A single motor neuron and all muscle fibers innervated by it.
p.39
General Properties of Muscle
What hormone is secreted by the parathyroid gland?
Parathyroid hormone (PTH).
p.38
Bone Development and Growth
What happens during callus ossification?
Callus is replaced by woven, spongy bone.
p.6
Structure of Skeletal Muscle
How do the globular regions of myosin interact?
Each heavy chain interacts with two light chains.
p.12
Muscle Twitch and Motor Units
What happens when the stimulus is stronger than the threshold?
An action potential occurs, and contraction is equal to that with the threshold stimulus.
p.3
Connective Tissue Coverings of Muscles
What is the epimysium?
Connective tissue that surrounds a whole muscle, encompassing many fascicles.
p.4
Structure of Skeletal Muscle
What is the function of the Z disk?
It serves as an attachment for actin myofilaments.
p.35
Bone Development and Growth
What happens in the Zone of Hypertrophy?
Chondrocytes mature and enlarge.
p.35
Bone Development and Growth
What characterizes the Zone of Calcification?
The matrix is calcified, and chondrocytes die.
p.35
Bone Development and Growth
What happens to cartilage in the ossified bone?
The cartilage on the diaphyseal side of the plate is replaced by bone.
p.28
Bone Development and Growth
When is woven bone typically formed?
During fetal development and during fracture repair.
p.7
Excitation-Contraction Coupling
What happens to sarcomeres during muscle contraction?
Sarcomeres shorten due to actin myofilaments sliding over myosin.
p.23
Neuromuscular Junction and Muscle Contraction
How does Isoproterenol affect the force of contraction?
It results in a higher force of contraction.
p.23
Muscle Twitch and Motor Units
What is the Frank Starling Law?
Stretching of the heart increases the force of contraction.
p.15
Properties of Smooth Muscle
What type of muscle fibers are involved in sprinting and walking?
Type IIb Fast-Twitch Glycolytic Fibers.
p.15
Properties of Smooth Muscle
What is the primary function of Type IIb fibers?
Short-term rapid and intense movement.
p.4
Structure of Skeletal Muscle
What are sarcomeres?
Highly ordered repeating units of myofilaments, extending from Z disk to Z disk.
p.5
Structure of Skeletal Muscle
What are the three subunits of the troponin complex?
Troponin T, Troponin I, and Troponin C.
p.12
Muscle Twitch and Motor Units
What is Multiple Motor Unit Summation?
The process by which the strength of contraction is increased by recruiting more motor units.
p.14
Excitation-Contraction Coupling
How does increased temperature affect muscle contractions?
It makes muscle enzymes more efficient.
p.18
Properties of Smooth Muscle
How is multiunit smooth muscle stimulated?
Each cell is stimulated independently by neurotransmitters released from autonomic nerve varicosities.
p.2
Properties of Cardiac Muscle
What is the major function of the heart?
It is the major source of movement of blood.
p.7
Muscle Twitch and Motor Units
What causes sarcomeres to lengthen during relaxation?
External forces, such as the contraction of antagonistic muscles.
p.4
Structure of Skeletal Muscle
What is the structure of skeletal muscle fibers?
They have several nuclei just inside the sarcolemma.
p.4
Structure of Skeletal Muscle
What are myofibrils?
They are packed within the cytoplasm (sarcoplasm) of muscle fibers.
p.23
Muscle Twitch and Motor Units
What happens to the ventricles when the heart receives a lot of blood?
The ventricles are stretched, resulting in an increased force of contraction.
p.17
Excitation-Contraction Coupling
What role do calcium ions (Ca2+) play in the excitation-contraction coupling of smooth muscle?
Calcium ions are crucial for initiating contraction by binding with calmodulin.
p.4
Structure of Skeletal Muscle
What gives skeletal muscle its striated appearance?
The arrangement of I bands, A bands, and H zones.
p.17
Excitation-Contraction Coupling
What is the result of myosin light chain kinase (MLCK) activation?
Myosin head is phosphorylated, allowing it to bind to actin and cause contraction.
p.11
Structure of Skeletal Muscle
Where is SERCA most abundantly found in skeletal muscle?
In the sarcoplasmic reticulum (SR).
p.7
Structure of Skeletal Muscle
What is the function of titin in muscle tissue?
Titin filaments provide extensibility and elasticity to muscles.
p.38
Bone Development and Growth
What do chondroblasts produce?
Cartilage within the collagen.
p.2
Properties of Cardiac Muscle
How is the heart controlled?
Involuntarily by the endocrine and autonomic nervous systems.
p.36
Bone Development and Growth
What factors determine the size and shape of a bone?
Genetics, nutrition, and hormones.
p.32
Structure of Skeletal Muscle
What does the endosteum line?
All internal spaces, including those in spongy bone.
p.5
Structure of Skeletal Muscle
What forms the filamentous actin (F-actin) in thin filaments?
Globular actin (G-actin) molecules.
p.6
Neuromuscular Junction and Muscle Contraction
What role do cross-bridges and hinges play in muscle contraction?
They are important for contraction.
p.3
Connective Tissue Coverings of Muscles
What does the perimysium do?
It is denser connective tissue surrounding a group of muscle fibers, known as a fasciculus.
p.31
Structure of Skeletal Muscle
What is the function of the epiphyseal plate?
It serves as the growth plate made of hyaline cartilage.
p.13
Muscle Twitch and Motor Units
What does the strength of muscle contraction depend on?
Recruitment of motor units.
p.14
Types of Muscle Tissue
What is the function of Type I skeletal muscle fibers?
Endurance; maintain posture; used in activities like marathon running.
p.13
Excitation-Contraction Coupling
What is tetanization in muscle contraction?
A state where successive contractions occur so rapidly that they fuse together, resulting in a smooth and continuous contraction.
p.15
Properties of Smooth Muscle
How do visceral smooth muscle cells function?
They are arranged in sheets and function as a unit.
p.10
Neuromuscular Junction and Muscle Contraction
What occurs when a crossbridge forms?
The myosin head binds to a new position on actin.
p.30
Structure of Skeletal Muscle
What is the role of perforating canals?
To deliver blood to central canals.
p.19
Regulation of Smooth Muscle
What is the function of activated myosin kinase in smooth muscle?
It attaches phosphate from ATP to myosin heads to activate the contractile process.
p.18
Properties of Smooth Muscle
What connects unitary (visceral) smooth muscle cells?
Gap junctions, allowing rapid depolarization to spread.
p.11
Muscle Twitch and Motor Units
What is a muscle twitch?
A muscle contraction in response to a stimulus that causes action potential in one or more muscle fibers.
p.38
Bone Development and Growth
What is the role of osteoblasts in bone formation?
Osteoblasts invade and form new bone.
p.39
General Properties of Muscle
What stimulates the release of PTH?
A reduction in blood calcium levels.
p.23
Muscle Twitch and Motor Units
What causes the increased force of contraction according to the Frank Starling Law?
Increased sensitivity of contraction to Ca2+ and closer interaction between actin and myosin.
p.27
Bone Development and Growth
What is the function of osteocytes in relation to the matrix?
They can make small amounts of matrix to maintain it.
p.2
Structure of Skeletal Muscle
How does the diameter of skeletal muscle fibers vary?
They tend to be smaller in small muscles and larger in large muscles.
p.38
Bone Development and Growth
What hormones control blood calcium levels?
Parathyroid hormone (PTH), Calcitriol, and Calcitonin.
p.27
Bone Development and Growth
How do nutrients transfer between osteocytes?
Nutrients diffuse through a tiny amount of liquid surrounding the cells and filling lacunae and canaliculi.
p.6
Structure of Skeletal Muscle
How are myosin heads attached to the rod portion?
By a hinge region that can bend.
p.10
Neuromuscular Junction and Muscle Contraction
What initiates crossbridge formation in muscle contraction?
ATP binds to the myosin head, causing the dissociation of the actin-myosin complex.
p.5
Structure of Skeletal Muscle
What is the structure of the thin filament in terms of actin?
Two strands of fibrous (F) actin form a double helix.
p.5
Structure of Skeletal Muscle
Where is the tropomyosin/troponin complex located?
In the groove between the F-actin strands.
p.11
Excitation-Contraction Coupling
What is the role of sarcoplasmic endoplasmic reticulum calcium ATPase (SERCA) in skeletal muscle?
It transports two molecules of Ca²⁺ into its lumen for each molecule of ATP hydrolyzed.
p.17
Properties of Smooth Muscle
How does the cycling of myosin cross bridges in smooth muscle compare to skeletal muscle?
Myosin cross bridges cycle more slowly in smooth muscle.
p.7
Neuromuscular Junction and Muscle Contraction
What is a synapse in the context of the neuromuscular junction?
It is the axon terminal resting in an invagination of the sarcolemma.
p.17
Properties of Smooth Muscle
What is the energy requirement for sustaining contraction in smooth muscle?
Smooth muscle requires less energy to sustain contraction.
p.39
General Properties of Muscle
How does PTH affect calcium in the kidneys?
It stimulates the reabsorption of calcium from urine in the kidney tubules.
p.5
Structure of Skeletal Muscle
What is the role of tropomyosin in thin filaments?
It binds as dimers and winds along the groove of the F-actin double helix.
p.14
Muscle Twitch and Motor Units
What happens to the strength of contractions during the Treppe effect?
Each subsequent contraction is stronger than the previous until they all equal after a few stimuli.
p.14
Excitation-Contraction Coupling
Why do contractions become stronger in the Treppe effect?
More Ca2+ remains in the sarcoplasm and is not all taken up into the sarcoplasmic reticulum.
p.4
Structure of Skeletal Muscle
What are I bands?
Regions from Z disks to the ends of thick filaments.
p.3
Neuromuscular Junction and Muscle Contraction
What is the role of motor neurons in muscle contraction?
They stimulate muscle fibers to contract, with cell bodies located in the brain or spinal cord.
p.30
Structure of Skeletal Muscle
What are circumferential lamellae?
Layers on the periphery of a bone.
p.13
Muscle Twitch and Motor Units
What is frequency summation?
The principle where individual twitch contractions add together as stimulation frequency increases.
p.33
Bone Development and Growth
What happens to bone after remodeling in ossification?
It cannot be distinguished as intramembranous or endochondral.
p.8
Neuromuscular Junction and Muscle Contraction
What occurs after ACh unbinds from the channel?
Acetylcholinesterase removes ACh from the synaptic cleft.
p.18
Properties of Smooth Muscle
What role does calmodulin play in smooth muscle relaxation?
Calmodulin is released from a complex with calcium.
p.7
Neuromuscular Junction and Muscle Contraction
What is the role of ATPase enzymes in muscle contraction?
They break down ATP, releasing energy used to bend the hinge region of the myosin molecule.
p.11
Muscle Twitch and Motor Units
What are the three phases of a muscle twitch?
Lag (latent), contraction, and relaxation.
p.2
Structure of Skeletal Muscle
What are the main components of skeletal muscle?
Muscle cells (fibers), connective tissue, blood vessels, and nerves.
p.39
General Properties of Muscle
What happens to bone when osteoclast activity increases due to PTH?
Bone is resorbed and calcium is released into the blood.
p.32
Structure of Skeletal Muscle
What is the structure of flat bones?
They have no diaphysis or epiphyses and consist of a sandwich of spongy bone between compact bone.
p.27
Bone Development and Growth
What are lacunae?
Spaces occupied by osteocyte cell bodies.
p.12
Muscle Twitch and Motor Units
How is the strength of contraction graded?
It ranges from weak to strong depending on stimulus strength.
p.2
Structure of Skeletal Muscle
From what do skeletal muscle fibers develop?
They develop from myoblasts.
p.28
Bone Development and Growth
How do osteoclasts contribute to bone resorption?
By pumping H+ ions across the membrane to form acid that eats away bone and releasing enzymes that digest bone.
p.3
Connective Tissue Coverings of Muscles
What is muscular fascia?
A connective tissue sheet that holds muscles together and separates them into functional groups.
p.28
Bone Development and Growth
What characterizes woven bone?
Collagen fibers that are randomly oriented.
p.13
Muscle Twitch and Motor Units
What happens as the frequency of stimulation increases?
Each new contraction occurs before the preceding one is over, leading to a progressive rise in total strength of contraction.
p.8
Neuromuscular Junction and Muscle Contraction
What role do Ca2+ ions play in the neuromuscular junction?
They enter the presynaptic terminal and trigger the release of ACh.
p.8
Excitation-Contraction Coupling
What happens when ACh binds to ligand-gated Na+ channels?
Na+ enters the postsynaptic cell, causing depolarization.
p.40
General Properties of Muscle
What is Osteomyelitis?
Inflammation of the bone.
p.10
Excitation-Contraction Coupling
What is SERCA's role in muscle contraction?
It helps in the reuptake of Ca2+ into the sarcoplasmic reticulum.
p.21
Excitation-Contraction Coupling
How does the action potential initiate contraction in cardiac muscle?
It causes calcium ions to be released into the muscle fiber cytosol from the sarcoplasmic reticulum.
p.1
Types of Muscle Tissue
What are some functions of smooth muscle?
Propelling urine, mixing food in the digestive tract, dilating/constricting pupils, and regulating blood flow.
p.22
Excitation-Contraction Coupling
What is the result of increased PKA phosphorylation in cardiac muscle?
Increased accumulation of Ca2+ ions in the sarcoplasmic reticulum (SR).
p.18
Properties of Smooth Muscle
How do intracellular calcium levels decrease in smooth muscle relaxation?
By SERCA or calcium being pumped out of the cell.
p.11
Excitation-Contraction Coupling
What happens to the troponin-tropomyosin complex during muscle relaxation?
Ca²⁺ moves away from the complex, allowing tropomyosin to block actin binding sites for myosin.
p.12
Muscle Twitch and Motor Units
How do motor units differ in large muscles compared to small muscles?
Large muscles have motor units with many muscle fibers, while small muscles have motor units with few muscle fibers.
p.12
Muscle Twitch and Motor Units
What does the all-or-none law state regarding muscle fibers?
Muscle fibers contract with equal force in response to each action potential.
p.12
Muscle Twitch and Motor Units
What happens with a sub-threshold stimulus?
There is no action potential and no contraction.
p.2
Structure of Skeletal Muscle
What is the structure of skeletal muscle fibers?
They are long, cylindrical, and multinucleated.
p.14
Muscle Twitch and Motor Units
What is the Treppe effect?
A graded response in muscle contractions due to multiple stimuli of the same strength.
p.39
General Properties of Muscle
What is the function of calcitonin?
It lowers blood calcium by inhibiting osteoclast activity.
p.27
Bone Development and Growth
What are canaliculi?
Canals occupied by osteocyte cell processes.
p.30
Structure of Skeletal Muscle
What is the function of blood vessels in the canals?
To provide direct flow of nutrients through cell processes of osteoblasts.
p.31
Structure of Skeletal Muscle
What happens at the epiphyseal line?
Bone stops growing in length.
p.5
Structure of Skeletal Muscle
How is the actin site involved in muscle contraction?
It can bind myosin during muscle contraction.
p.8
Neuromuscular Junction and Muscle Contraction
What is the neuromuscular junction (NMJ)?
The synapse between a motor neuron and a muscle fiber.
p.31
Structure of Skeletal Muscle
How do nutrients and wastes travel to and from osteocytes?
Via interstitial fluid of lacunae and canaliculi, and from osteocyte to osteocyte by gap junctions.
p.28
Bone Development and Growth
What is the process of remodeling in bone?
Removing old bone and adding new bone, where woven bone is remodeled into lamellar bone.
p.10
Neuromuscular Junction and Muscle Contraction
What results from the conformational change of myosin heads?
The power stroke occurs, causing the filaments to slide past each other.
p.10
Excitation-Contraction Coupling
What is the role of the RYR receptor in excitation-contraction coupling?
It releases Ca2+ into the myoplasm when activated.
p.21
Properties of Cardiac Muscle
How do intercalated discs affect electrical resistance in cardiac muscle?
Electrical resistance through the intercalated disc is only 1/400 of the resistance through the outside membrane.
p.1
General Properties of Muscle
What is elasticity in muscle properties?
The ability of muscle to recoil to its original resting length after being stretched.
p.1
Types of Muscle Tissue
What is the primary function of skeletal muscle?
Responsible for locomotion, facial expressions, posture, respiratory movements, and other types of body movement.
p.18
Properties of Smooth Muscle
How is smooth muscle regulated by the nervous system?
Through autonomic nerve fibers that secrete neurotransmitters from varicosities.
p.36
Bone Development and Growth
What is the periosteum of the groove transformed into?
The endosteum of the tunnel.
p.7
Sliding Filament Model
Do actin and myosin change length during contraction?
No, actin and myosin do not change length during contraction.
p.36
Bone Development and Growth
What completes the formation of the osteon?
The production of additional concentric lamellae that fill in the tunnel.
p.39
General Properties of Muscle
What is one direct effect of PTH?
Activates osteoclasts, increasing their number and preventing inhibition of their formation.
p.27
Bone Development and Growth
What are osteocytes?
Mature bone cells that are stellate and surrounded by matrix.
p.4
Structure of Skeletal Muscle
What are the two types of myofilaments in skeletal muscle?
Thin (actin) and thick (myosin) myofilaments.
p.15
Properties of Smooth Muscle
What are the characteristics of smooth muscle fibers?
Not striated, smaller than skeletal muscle fibers, spindle-shaped with a single central nucleus.
p.15
Properties of Smooth Muscle
What is the role of caveolae in smooth muscle?
They are indentations in the sarcolemma that may act like T tubules.
p.15
Properties of Smooth Muscle
What replaces Z disks in smooth muscle?
Dense bodies, which have noncontractile intermediate filaments.
p.27
Bone Development and Growth
What are precursors of hydroxyapatite stored in?
Vesicles, then released by exocytosis.
p.30
Structure of Skeletal Muscle
What surrounds the central canal in compact bone?
Concentric lamellae of bone.
p.15
Properties of Smooth Muscle
What are the two types of smooth muscle?
Visceral (or unitary) smooth muscle and multi-unit smooth muscle.
p.33
Bone Development and Growth
What is intramembranous ossification?
Ossification that takes place in connective tissue membrane.
p.33
Bone Development and Growth
What is endochondral ossification?
Ossification that takes place in cartilage.
p.13
Excitation-Contraction Coupling
What occurs at a critical frequency level during muscle contraction?
Successive contractions fuse together, making the muscle contraction appear smooth and continuous.
p.1
General Properties of Muscle
What is contractility in muscle properties?
The ability of a muscle to shorten with force.
p.22
Excitation-Contraction Coupling
What is the primary mechanism for relaxation of cardiac muscle?
SERCA (Sarcoplasmic Reticulum Ca2+ ATPase).
p.22
Excitation-Contraction Coupling
What does the 3Na - 1Ca antiporter do during cardiac muscle relaxation?
It helps in the removal of Ca2+ from the cytosol.
p.26
Types of Muscle Tissue
What is a characteristic of Hyaline cartilage?
It is flexible and resilient.
p.19
Regulation of Smooth Muscle
Name some hormones that affect smooth muscle contraction.
Epinephrine, norepinephrine, angiotensin II, endothelin, vasopressin, oxytocin, and serotonin.
p.34
Bone Development and Growth
What are the two types of cartilage growth involved in bone growth?
Interstitial cartilage growth and appositional growth on the surface of the cartilage.
p.25
Structure of Skeletal Muscle
What do chondroblasts do?
They form the matrix of cartilage.
p.22
Excitation-Contraction Coupling
What happens to the force of contraction with the next action potential after increased Ca2+ accumulation?
It will have a greater force of contraction.
p.25
Connective Tissue Coverings of Muscles
What is the perichondrium?
A double-layered connective tissue sheath that covers cartilage.
p.16
Structure of Skeletal Muscle
How does the arrangement of actin filaments differ in smooth muscle compared to skeletal muscle?
In smooth muscle, actin filaments are attached to dense bodies instead of Z disks.
p.25
Structure of Skeletal Muscle
What are the two types of cartilage growth?
Appositional growth and interstitial growth.
p.29
Structure of Skeletal Muscle
What types of lamellae are found in compact bone?
Concentric, circumferential, and interstitial lamellae.
p.20
Properties of Cardiac Muscle
What structural feature distinguishes cardiac muscle from skeletal muscle?
Cardiac muscle is striated like skeletal muscle.
p.12
Muscle Twitch and Motor Units
What occurs with a threshold stimulus?
An action potential occurs, leading to contraction.
p.3
General Properties of Muscle
What gives skeletal muscle its striated appearance?
The light and dark banding.
p.6
Neuromuscular Junction and Muscle Contraction
What is the ATPase function of myosin?
It provides energy for muscle contraction.
p.17
Excitation-Contraction Coupling
What happens when calcium ions bind with calmodulin in smooth muscle?
The calcium-calmodulin complex activates myosin light chain kinase (MLCK).
p.3
Connective Tissue Coverings of Muscles
What is the endomysium?
Loose connective tissue with reticular fibers that surrounds individual muscle fibers.
p.28
Bone Development and Growth
From what cells are osteoclasts derived?
Monocytes, which are formed from stem cells in red bone marrow.
p.28
Bone Development and Growth
What type of cells can mesenchymal stem cells become?
Chondroblasts or osteoblasts.
p.14
Types of Muscle Tissue
What are Type I skeletal muscle fibers also known as?
Slow-twitch oxidative fibers.
p.30
Structure of Skeletal Muscle
What are interstitial lamellae?
Remnants of osteons located between osteons.
p.19
Regulation of Smooth Muscle
What happens when a hormone binds to its receptor in smooth muscle?
It activates a G protein mechanism or causes depolarization of the plasma membrane.
p.8
Neuromuscular Junction and Muscle Contraction
What is done with choline after ACh is broken down?
Choline is symported with Na+ into the presynaptic terminal.
p.8
Neuromuscular Junction and Muscle Contraction
How is ACh reformed after being broken down?
It is taken up by synaptic vesicles.
p.25
Structure of Skeletal Muscle
What are the four components of the skeletal system?
Bone, cartilage, tendons, and ligaments.
p.16
Properties of Smooth Muscle
How do smooth muscle cells contract?
They contract together as a single unit.
p.26
Types of Muscle Tissue
Where can Fibrocartilage be found?
In knee menisci and the annulus fibrosus of intervertebral discs.
p.34
Bone Development and Growth
What is appositional growth?
Growth that occurs on old bone and/or on cartilage surface.
p.16
Structure of Skeletal Muscle
What are caveolae in smooth muscle?
They are structures similar to the transverse tubule (T-tubule) system of skeletal muscle.
p.20
Properties of Smooth Muscle
What complex is formed when Ca2+ accumulates inside smooth muscle cells?
The Ca2+-calmodulin complex.
p.36
Bone Development and Growth
Why is Vitamin D important for bone health?
It is necessary for the absorption of calcium from the intestines.
p.39
General Properties of Muscle
What is the role of calcitriol?
It increases calcium absorption in the small intestine.
p.32
Structure of Skeletal Muscle
How do short and irregular bones differ from long bones?
They have compact bone surrounding a spongy bone center and do not have diaphyses or elongated structures.
p.28
Bone Development and Growth
What is the rugose border in osteoclasts?
The area where the cell membrane borders bone and resorption occurs.
p.38
Bone Development and Growth
How does calcium enter and leave the bone?
Calcium enters when osteoblasts create new bone and leaves when osteoclasts break down bone.
p.15
Properties of Smooth Muscle
What is required to initiate contractions in smooth muscle?
Calcium ions (Ca2+), which bind to calmodulin to regulate myosin kinase.
p.4
Structure of Skeletal Muscle
What is the H zone?
The region in the A band where actin and myosin do not overlap.
p.4
Structure of Skeletal Muscle
What is the M line?
The middle of the H zone, holding delicate filaments.
p.35
Bone Development and Growth
What do chondrocytes near the surface of the articular cartilage resemble?
They are similar to those in the zone of resting cartilage.
p.28
Bone Development and Growth
What is lamellar bone?
A type of bone that is organized in layers, unlike woven bone.
p.21
Properties of Cardiac Muscle
What is the functional syncytium in cardiac muscle?
It is the result of intercalated discs that allow action potentials to spread rapidly among cells.
p.22
Excitation-Contraction Coupling
What role does the sarcolemma Ca2+ pump play in cardiac muscle relaxation?
It aids in the extrusion of Ca2+ from the cell.
p.34
Bone Development and Growth
When does cartilage formation begin during development?
At the end of the fourth week of development.
p.37
Bone Development and Growth
What are the effects of a lack of vitamin C?
Wounds do not heal and teeth may fall out.
p.21
Excitation-Contraction Coupling
What initiates the sliding of actin and myosin filaments in cardiac muscle?
The rapid influx of calcium ions into the myofibrils.
p.26
Types of Muscle Tissue
What is the structure of Fibrocartilage?
Rows of thick collagen fibers alternating with rows of chondrocytes.
p.37
Bone Development and Growth
Which hormones are involved in bone growth?
Reproductive hormones such as estrogen and testosterone.
p.24
General Properties of Muscle
What gait is commonly observed in patients with DMD?
Waddling gait due to hip muscle weakness.
p.9
Excitation-Contraction Coupling
What forms cross-bridges during muscle contraction?
The heads of myosin myofilaments bind to exposed active sites on G actin.
p.24
General Properties of Muscle
How does DMD affect the skeletal system?
Causes contractures and severe deformities like curvature of the spinal column.
p.6
Neuromuscular Junction and Muscle Contraction
What is the importance of myosin heads?
They can bind to active sites on actin molecules to form cross-bridges.
p.35
Bone Development and Growth
What occurs in the Zone of Proliferation?
New cartilage is produced as chondrocytes divide and form stacks of cells.
p.33
Bone Development and Growth
What type of bones in the skull have sinuses lined by mucous membranes?
Some flat and irregular bones.
p.31
Structure of Skeletal Muscle
What replaces red marrow in the medullary cavity of adults?
Yellow marrow, except for proximal epiphyses of arm and thigh bones.
p.8
Excitation-Contraction Coupling
What happens when an action potential arrives at the presynaptic terminal?
It causes voltage-gated Ca2+ channels to open.
p.35
Bone Development and Growth
How does bone growth in width occur?
Osteoblasts beneath the periosteum lay down bone to form ridges separated by grooves.
p.35
Bone Development and Growth
What happens to the groove formed by osteoblasts?
The groove is transformed into a tunnel when the bone grows.
p.21
Properties of Cardiac Muscle
How do action potentials travel in cardiac muscle?
Ions flow easily along the axes of the cardiac muscle fibers, allowing action potentials to travel from one cell to the next.
p.9
Excitation-Contraction Coupling
What initiates the action potential in muscle fiber contraction?
An action potential produced at the neuromuscular junction.
p.9
Excitation-Contraction Coupling
What is the role of calcium ions (Ca2+) in muscle contraction?
They bind to troponin, causing tropomyosin to move and expose active sites on G actin.
p.25
Structure of Skeletal Muscle
What are chondrocytes?
Cells surrounded by the matrix within lacunae.
p.34
Bone Development and Growth
Why can't interstitial growth occur in bone?
Because the matrix is solid.
p.25
Connective Tissue Coverings of Muscles
What are the two layers of the perichondrium?
Inner layer (more delicate, fewer fibers, contains chondroblasts) and outer layer (contains blood vessels and nerves).
p.16
Excitation-Contraction Coupling
What is the contraction dependency in smooth muscle?
Contraction is usually dependent on the presence of caveolae.
p.20
Properties of Smooth Muscle
What is the result of MLCK activity?
Phosphorylation of the myosin light chain, enabling contraction.
p.13
Muscle Twitch and Motor Units
What are the types of stimuli that affect muscle contraction?
Submaximal, maximal, and supramaximal stimuli.
p.10
Neuromuscular Junction and Muscle Contraction
What happens after ATP is hydrolyzed during muscle contraction?
Myosin heads return to their resting conformation.
p.35
Bone Development and Growth
How does growth at articular cartilage affect bone size?
It increases the size of bones without epiphyses, such as short bones.
p.10
Excitation-Contraction Coupling
What does the DHPR receptor do?
It is a voltage-gated Ca2+ channel that undergoes a conformational change during an action potential.
p.10
Excitation-Contraction Coupling
What is the function of calsequestrin?
It binds Ca2+ at low affinity, allowing high concentration storage and facilitating Ca2+ release.
p.19
Regulation of Smooth Muscle
What occurs during the cycle of cross-bridge formation in smooth muscle?
Formation, movement, detachment, and reformation of cross-bridges.
p.19
Regulation of Smooth Muscle
How does relaxation occur in smooth muscle?
When myosin phosphatase removes phosphate from myosin.
p.34
Bone Development and Growth
Where does growth in length occur in bones?
At the epiphyseal plate, organized into five zones.
p.25
Structure of Skeletal Muscle
What is the composition of the cartilage matrix?
Collagen fibers for strength and proteoglycans for resiliency.
p.37
Bone Development and Growth
What is a callus in the context of bone repair?
A mass of tissue that forms at a fracture site to connect broken ends of the bone.
p.20
Properties of Smooth Muscle
What are the products of phospholipase C activity?
DAGs (diacylglycerols) and IP3 (inositol triphosphates).
p.26
Bone Development and Growth
What is the role of osteoblasts?
Formation of bone through ossification or osteogenesis.
p.24
General Properties of Muscle
What respiratory issue is associated with DMD?
Weakness of respiratory muscles leads to inadequate respiratory movements, increasing pneumonia risk.
p.3
Neuromuscular Junction and Muscle Contraction
How do axons connect to muscle fibers?
Axons branch so that each muscle fiber is innervated.
p.14
Types of Muscle Tissue
What type of muscle fibers are Type IIa?
Fast-twitch oxidative fibers.
p.33
Bone Development and Growth
What do both intramembranous and endochondral ossification produce?
Woven bone that is then remodeled.
p.19
Regulation of Smooth Muscle
Which ions are affected by hormone receptors in smooth muscle?
Calcium (Ca2+) and sodium ions.
p.19
Regulation of Smooth Muscle
What role does calmodulin play in smooth muscle contraction?
It binds with calcium ions and activates myosin kinase.
p.21
Properties of Cardiac Muscle
What happens when one cardiac muscle cell becomes excited?
The action potential spreads to all tightly bound cardiac muscle cells.
p.26
Types of Muscle Tissue
What type of fibers are found in Hyaline cartilage?
Collagen is the only fiber.
p.16
Properties of Smooth Muscle
What role do gap junctions play in smooth muscle contraction?
They allow waves of contraction through numerous connections.
p.9
Structure of Skeletal Muscle
What is a triad in muscle fibers?
A structure consisting of a T tubule and two adjacent terminal cisternae.
p.26
Bone Development and Growth
What happens if collagen is removed from bone?
The bone becomes too brittle.
p.29
Structure of Skeletal Muscle
What are central or Haversian canals?
Canals that are parallel to the long axis of the bone.
p.29
Structure of Skeletal Muscle
What are perforating or Volkmann’s canals?
Canals that connect Haversian canals and allow for blood supply and communication.
p.19
Regulation of Smooth Muscle
How do hormones regulate smooth muscle contraction?
By interacting with hormone-gated receptors in the membrane.
p.33
Bone Development and Growth
Where does intramembranous ossification take place?
In connective tissue membrane formed from embryonic mesenchyme.
p.1
General Properties of Muscle
What does extensibility refer to in muscle properties?
The ability of a muscle to be stretched to its normal resting length and beyond to a limited degree.
p.34
Bone Development and Growth
What bones are formed through endochondral ossification?
Bones of the base of the skull, part of the mandible, epiphyses of the clavicles, and most of the remaining bones of the skeletal system.
p.26
Types of Muscle Tissue
What is a lacuna?
A cavity in the matrix holding a chondrocyte.
p.37
Bone Development and Growth
Which hormone stimulates interstitial cartilage growth?
Growth hormone from the anterior pituitary.
p.21
Excitation-Contraction Coupling
What occurs during relaxation of cardiac muscle after an action potential?
Calcium ions are transported back into the sarcoplasmic reticulum or into the T tubules.
p.1
Types of Muscle Tissue
What is the unique characteristic of cardiac muscle?
It is autorhythmic in some locations of the body.
p.26
Bone Development and Growth
What are the components of bone matrix?
Organic (collagen and proteoglycans) and inorganic (hydroxyapatite).
p.34
Bone Development and Growth
What characterizes the zone of resting cartilage in the epiphyseal plate?
It contains slowly dividing chondrocytes.
p.20
Properties of Smooth Muscle
What role do DAG and IP3 play in smooth muscle contraction?
They act as second messengers that activate Ca2+ channels.
p.25
Structure of Skeletal Muscle
What occurs during interstitial growth?
Chondrocytes divide and add more matrix between the cells.
p.20
Properties of Cardiac Muscle
What unique structures are present in cardiac muscle cells?
Intercalated disks and gap junctions.
p.10
Neuromuscular Junction and Muscle Contraction
What is released during the power stroke of muscle contraction?
Inorganic phosphate (P) is released.
p.30
Structure of Skeletal Muscle
How do perforating canals run in relation to the long axis?
Perpendicular to the long axis.
p.33
Bone Development and Growth
What bones are formed by intramembranous ossification?
Many skull bones, part of the mandible, and diaphyses of clavicles.
p.26
Types of Muscle Tissue
What are the three types of cartilage?
Hyaline, Elastic, and Fibrocartilage.
p.40
General Properties of Muscle
What is Osteoporosis?
Reduced bone mass; fracture prone.
p.22
Neuromuscular Junction and Muscle Contraction
What is the effect of increased cAMP in cardiac muscle?
It increases PKA phosphorylation of proteins.
p.24
General Properties of Muscle
What is a primary characteristic of Duchenne Muscular Dystrophy (DMD)?
Slow motor development with progressive weakness and muscle atrophy.
p.29
Structure of Skeletal Muscle
What are trabeculae in spongy bone?
Interconnecting rods or plates of bone that serve as scaffolding.
p.26
Bone Development and Growth
What happens if mineral is removed from bone?
The bone becomes too bendable.
p.16
Structure of Skeletal Muscle
What is the development level of the sarcoplasmic reticulum in smooth muscle?
The sarcoplasmic reticulum is less developed in smooth muscle.
p.25
Structure of Skeletal Muscle
What occurs during appositional growth?
New chondrocytes and matrix are added at the periphery.
p.1
General Properties of Muscle
Define excitability in the context of muscle.
The capacity of muscle to respond to a stimulus from our nerves.
p.33
Bone Development and Growth
What are centers of ossification?
Locations in the membrane where ossification begins.
p.21
Excitation-Contraction Coupling
What role do L-type voltage-gated calcium channels play in cardiac muscle contraction?
They open in T tubules, allowing calcium ions to enter the muscle fiber.
p.25
Structure of Skeletal Muscle
What types of cartilage are there?
Hyaline, fibrocartilage, and elastic cartilage.
p.1
Types of Muscle Tissue
How is smooth muscle controlled?
Involuntarily by the endocrine and autonomic nervous systems.
p.29
Structure of Skeletal Muscle
How are fibers oriented in lamellae?
In one direction in each layer, but in different directions in different layers for strength.
p.16
Properties of Smooth Muscle
What are the structural arrangements of smooth muscle?
They can be sheets (like in blood vessels), bundles (like arrector pili, iris, ciliary), or single cells (like in the capsule of the spleen).
p.37
Bone Development and Growth
What happens during internal callus formation?
Blood vessels grow into the clot in the hematoma.
p.20
Properties of Smooth Muscle
What is the function of IP3 in smooth muscle cells?
It binds to receptors on the sarcoplasmic reticulum, promoting Ca2+ outflux into the cytosol.
p.33
Bone Development and Growth
What are fontanels?
Large membrane-covered spaces between developing skull bones that are unossified.
p.25
General Properties of Muscle
What is the leading cause of death for DMD patients?
Respiratory failure due to muscle degeneration.
p.1
Types of Muscle Tissue
Where is smooth muscle found?
In the walls of hollow organs, blood vessels, eyes, glands, and skin.
p.26
Types of Muscle Tissue
Where is Elastic cartilage found?
In the epiglottis, larynx, and outer ear.
p.16
Properties of Smooth Muscle
What is a characteristic of smooth muscle regarding rhythm?
Smooth muscle is often autorhythmic.
p.9
Excitation-Contraction Coupling
What happens when the T tubules depolarize?
Gated Ca2+ channels in the sarcoplasmic reticulum open, increasing permeability to Ca2+.
p.25
Structure of Skeletal Muscle
What is articular cartilage?
Cartilage that covers bones at joints and has no perichondrium.
p.24
General Properties of Muscle
What is the life expectancy for many DMD patients?
Few live beyond 20 years of age.
p.24
General Properties of Muscle
What digestive problems can arise from DMD?
Enlarged colon diameter and twisting of the small intestine, leading to reduced nutrient absorption.
p.34
Bone Development and Growth
When does some ossification begin during development?
Around week eight; some does not begin until 18-20 years of age.
p.40
General Properties of Muscle
What is Thoracotomy?
Incision into the chest/thorax.
p.34
Bone Development and Growth
What happens to the epiphyseal plate as one ages?
It ossifies, becoming the epiphyseal line, typically between 12-25 years of age.
p.26
Types of Muscle Tissue
What is the function of Fibrocartilage?
It resists compression and tension.
p.22
Neuromuscular Junction and Muscle Contraction
What is the effect of isoproterenol on cardiac contraction?
It enhances the force of contraction.
p.24
General Properties of Muscle
What causes the enlargement of calf muscles in DMD patients?
Increase of connective tissue and fat between muscle fibers.
p.9
Excitation-Contraction Coupling
What is the sarcoplasmic reticulum's role in muscle contraction?
It releases calcium ions into the sarcoplasm when depolarized.
p.20
Properties of Smooth Muscle
How does DAG facilitate Ca2+ influx?
By binding to plasma membrane Ca2+ receptors and opening a channel.
p.20
Properties of Smooth Muscle
What does the Ca2+-calmodulin complex activate?
Myosin Light Chain Kinase (MLCK).
p.16
Properties of Smooth Muscle
What distinguishes multi-unit smooth muscle?
Cells or groups of cells act as independent units and can contract independently.
p.9
Excitation-Contraction Coupling
What is the function of troponin in muscle contraction?
Troponin binds calcium ions and facilitates the exposure of active sites on G actin.
p.37
Bone Development and Growth
What do osteoclasts do during bone repair?
They break down dead tissue.
p.29
Structure of Skeletal Muscle
What is an osteon or Haversian system?
A structure consisting of a central canal, its contents, associated concentric lamellae, and osteocytes.
p.20
Properties of Cardiac Muscle
How do action potentials in cardiac muscle differ from those in skeletal muscle?
They have longer duration and longer refractory periods.
