Chapter 11: The Musculoskeletal System Flashcards
Muscle can be divided into the three different subtypes: ___________ muscle, __________ muscle, and ____________ muscle.
- Skeletal muuscle
- Smooth muscle
- Cardiac muscle
All muscle is capable of contraction, which relies on _____________ ions.
Calcium ions
_____________ muscle is responsible for voluntary movement and is therefore innervated by the somatic nervous system.
Skeletal muscle
Due to the arrangement of actin and myosin into repeating units called _____________, it appears striped or striated when viewed microscopically.
Sarcomeres
Does skeletal muscle have one, two or multi nuclei?
Skeletal muscle is multinucleated.
______________, also known as ______________, have high myoglobin content and primarily derive their energy aerobically.
- Red fibers
- Slow-twitch fibers
______________ is an oxygen carrier that uses iron in a heme group to bind oxygen, imparting a red colour.
Myoglobin
______________, also known as _______________, contain much less myoglobin. Because there is less myoglobin, and therefore less iron, the colour is lighter.
- White fibers
- Fast-twitching fibers
Muscles that contract slowly, but that can sustain activity (such as the muscles that support posture), contain a predominance of ___________ fibers.
Red fibers
Muscles that contract rapidly, but fatigue quickly, contain mostly ___________ fibers.
White fibers
________________ is responsible for involuntary action. It is controlled by the autonomic nervous system. Their cells have a single nucleus located in the centre of the cell.
Smooth muscle
______________ cells contain actin and myosin, but the fibers are not as well-organized, so striations cannot be seen.
Smooth muscle
Compared to skeletal muscle, smooth muscle is capable of more sustained contractions; a constant state of low-level contraction, as may be seen in the blood vessels, is called ____________.
Tonus
Smooth muscle can actually contract without nervous system input in what is known as __________________. The muscle cells contract directly in response to stretch or other stimuli.
Myogenic activity
______________ is primarily uninucleate, but cells may contain two nuclei. Its contraction is involuntary and innervated by the autonomic nervous system. It appears striated like skeletal.
Cardiac muscle
Cardiac muscle cells are connected by _________________, which contains many gap junction.
Intercalated discs
Cardiac muscles are able to define and maintain their own rhythm, termed ________________.
Myogenic activity
The _____________ provides parasympathetic outflow to the heart and slows the heart rate.
Vagus nerve
________________ from sympathetic neurons or ________________ from the adrenal medulla binds to adrenergic receptors in the heart, causing an increased heart rate and greater contractility.
- Norepinephrine
- Epinephrine
The _____________ is the basic contractile unit of skeletal muscle.
Sarcomere
____________ acts as a spring and anchors the actin and myosin together, preventing excessive stretching of the muscle.
Titin
____________ define the boundaries of each sarcomere.
Z-lines
The ___________ runs down the centre of the sarcomere, through the middle of the myosin filaments.
M-line
The ___________ is the region containing exclusively thin filaments.
I-band
The ___________ contains only thick filaments.
H-zone
The ___________ contains the thick filaments in their entirety, including any overlap with thin filaments.
A-band
Sarcomeres are attached end to end to form ________________.
Myofibrils
Myofibrils are surrounded by a covering known as the ___________________ (_____), a modified endoplasmic reticulum that contains a high concentration of Ca2+ ions.
Sarcoplasmic reticulum (SR)
The ______________ is a modified cytoplasm located just outside of the sarcoplasmic reticulum.
Sarcoplasm
The cell membrane of a myocyte is known as the _____________.
Sarcolemma
The sarcolemma is capable of propagating an action potential and can distribute the action potential to all sarcomeres in a muscle using a system of _________________ (__________) that are oriented perpendicularly to the myofibrils.
Transverse tubules (T-tubules)
Each myocyte, or muscle cell, contains many myofibrils arranged in parallel and can also be called a ______________.
Muscle fiber
Many myocytes in parallel form a __________.
Muscle
Muscle contraction starts at the _________________, where the nervous system communicates with muscles via motor (efferent) neurons.
Neuromuscular junction
The signal from neuromuscular junction travels down the neuron until it reaches the ________________ (______________), where acetylcholine is released into the synapse.
Nerve terminal (synaptic bouton)
In the case of the neuromuscular junction, the nerve terminal can also be called the _______________.
Motor end plate
Acetylcholine binds to receptors on the sarcolemma, causing ______________.
Depolarization
Each nerve terminal controls a group of myocytes; together, the nerve terminal and its myocytes constitute a ______________.
Motor unit
Calcium ion binds to ____________, leading to a conformational change in ____________, which exposes the myosin-binding sites of actin.
- Troponin
- Tropomyosin
Actin-Myosin Cross-Bridge Cycle (1)
Myosin carrying hydrolyzed ATP (ADP and an inorganic phosphate, Pi) is able to bind with the __________________.
Myosin-binding site
Actin-Myosin Cross-Bridge Cycle (2)
The release of the inorganic phosphate and ADP in rapid succession provides the energy for the ______________ and results in sliding of the actin filament over the myosin filament.
Powerstroke
Actin-Myosin Cross-Bridge Cycle (3)
ATP binds to the myosin head, releasing it from actin. This ATP is hydrolyzed to ADP and Pi, which ___________ the myosin head so that it is in position to initiate another cross-bridge cycle.
Recocks
The repetitive binding and releasing of myosin heads on actin filaments allows the thin filament to slide along the thick filament, causing sequential shortening of the sarcomere. This is known as the _____________________.
Sliding filament mode
When a sarcomere contracts, both the H-zone and I-band shorten, while the ______________ is unchanged.
A-band
It is the dissociation of ADP and Pi from myosin that is responsible for the ______________, not the hydrolysis of ATP. The binding of ATP is required for releasing the myosin head from the actin filament.
Powerstroke
Acetylcholine is degraded in the synapse by the enzyme known as __________________.
Acetylcholinesterase
The _______________ takes up calcium from sarcoplasm. It tightly controls intracellular calcium concentrations so that muscles are contracted only when necessary.
Sarcoplasmic reticulum
A _______________ is the response of a single muscle fiber to a brief stimulus at or above threshold.
Simple twitch
A simple twitch consists of a ____________ period, _____________ period, and ______________ period.
- Latent
- Contraction
- Relaxation
The ________________ is the time between reaching threshold and the onset of contraction.
Latent period
During _________________, the action potential spreads along the muscle and allows for calcium to be released from the sarcoplasmic reticulum.
Latent period
The _____________ happens when calcium is cleared from the sarcoplasm, the muscle is therefore relaxed.
Relaxation period
If a muscle fiber is exposed to frequent and prolonged stimulation, it will have insufficient time to relax. The contractions will combine, become stronger and more prolonged. This is known as ___________________.
Frequency summation
If the muscle contractions become so frequent (frequency summation) that the muscle is unable to relax at all, this is known as ____________.
Tetanus
______________ is created by transferring a phosphate group from ATP to creatine during times of rest.
Creatine phosphate
The difference between the amount of oxygen needed by the muscles and the actual amount present is called the ______________.
Oxygen debt
There are two types of skeletons: _____________ and ______________.
- Exoskeleton
- Endoskeleton
______________ encase whole organisms and are usually found in arthropods, such as crustaceans and insects.
Exoskeleton
Vertebrates, including humans, have _____________. These are internal, but are not able to protect the soft tissue structures as well as exoskeleton.
Endoskeleton
_______________ are much better able to accommodate the growth of a larger organism.
Endoskeleton
_______________ must be shed and regrown to accommodate growth.
Exoskeletons
The components of our skeletal system are divided into ___________ and ___________ skeletons.
- Axial skeleton
- Appendicular skeleton
The ______________ consists of the skull, vertebral column, rib cage, and hyoid bone (a small bone in the anterior neck used for swallowing); it provides the basic central framework for the body.
Axial skeleton
The _________________ consists of the bones of the limbs (humerus, radius, ulna, carpals, metacarpals, and phalanges in the upper limb; and femur, tibia and fibula, tarsals, metatarsals, and phalanges in the lower limb); the pectoral girdle (scapula and clavicle); and pelvis.
Appendicular skeleton
The skeleton is created from two major components: ____________ and ____________.
- Bone
- Cartilage
_____________ is a connective tissue derived from embryonic mesoderm.
Bone
Bone’s characteristic strength comes specifically from _____________.
Compact bone
The other type of bone structure is ____________ or _______________ bone.
- Spongy
- Cancellous
The lattice structure of spongy bone is visible under microscopy and consists of bony spicules (points) known as _____________.
Trabeculae
The cavities between trabeculae are filled with _______________, which may be either red or yellow.
Bone marrow
_______________ is filled with hematopoietic stem cells, which are responsible for the generation of all the cells in our blood.
Red marrow
_____________ is composed primarily of fat and is relatively inactive.
Yellow marrow
Bones in the appendicular skeleton are typically _______________.
Long bones
Long bones in the appendicular skeleton are characterized by cylindrical shafts called _____________ that swell at each end to form _____________, and that terminate at _____________.
- Diaphyses
- Metaphyses
- Epiphyses
The outermost portions of bone are composed of ____________ bone, whereas the internal core is made of ____________ bone.
- Compact bone
- Spongy bone
Long bone diaphyses and metaphases are full of ______________.
Bone marrow
At the internal edge of epiphysis is an _____________ (__________) __________, which is a cartilaginous structure and the site of longitudinal growth.
Epiphyseal (growth) plate
A fibrous sheath called the ______________ surrounds the long bone to protect it as well as serve as a site for muscle attachment.
Periosteum
Some _____________ cells are capable of differentiating into bone-forming cells; a healthy ______________ is necessary for bone growth and repair.
- Periosteal cells
- Periosteum
_____________ attach muscle to bone.
Tendons
______________ hold bones together at joints.
Ligaments
The strength of compact bone comes from the ______________, which has both organic and inorganic components.
Bone matrix
The inorganic components in bone matrix include calcium, phosphate, and hydroxide ions, which harden together to form _________________ crystals.
Hydroxyapatite crystals
The bony matrix is ordered into structural units known as ___________ or ________________.
- Osteons
- Haversian systems
Each of the osteon contains concentric circles of bony matrix called ____________ surrounding a central microscopic channel.
Lamellae
Longitudinal channels (those with an axis parallel to the bone) are known as _________________.
Haversian canals
Transverse channels (those with an axis perpendicular to the bone) are known as ________________.
Volkmann’s canals
Between the lamellar rings are small spaces called ______________.
Lacunae
The lacunae house mature bone cells known as _____________.
Osteocytes
The lacunae are interconnected by tiny channels called ______________ that allow for the exchange of nutrients and wastes between osteocytes and the Haversian and Volkmann’s canals.
Canaliculi
Two cell types are largely responsible for building and maintaining strong bones: ______________ and ______________.
- Osteoblasts
- Osteoclasts
______________ are the polynucleated resident macrophages of bone, resorb bone.
Osteoclasts
____________ build bone.
Osteoblasts
____________, a peptide hormone released by the parathyroid glands in response to low blood calcium, promotes resorption of bone, increasing the concentration of calcium and phosphate in the blood.
Parathyroid hormone
____________, which is activated by parathyroid hormone, promotes the resorption of bone.
Vitamin D
_____________, a peptide hormone released by the parafollicular cells of the thyroid in response to high blood calcium, promotes bone formation, lowering blood calcium levels.
Calcitonin
____________ is softer and more flexible than bone.
Cartilage
Cartilage consists of a firm but elastic matrix called _______________.
Chondrin
Chondrin is secreted by cells called __________________.
Chondrocytes
Cartilage differs from bone in that it is ______________ (without blood and lymphatic vessels) and is not innervated.
Avascular
Most of the bones of the body are created by the hardening of cartilage into bone. This process is known as ____________________ and is responsible for the formation of most of the long bones of the body.
Endochondral ossification
Bones may be formed through ____________________, in which undifferentiated embryonic connective tissue is transformed into, and replaced by, bone. This occurs in bones of the skull.
Intramembranous ossification
Undifferentiated embryonic connective tissue is also called _______________.
Mesenchymal tissue
Like bone and cartilage, joints are made of connective tissue and come in two major varieties: _______________ and ______________.
- Immovable
- Moveable
______________ consist of bones that are fused together to form sutures or similar fibrous joints. These joints are found primarily in the head, where they anchor bones of the skull together.
Immovable joints
_______________, include hinge joints (like the elbow or knee), ball-and-socket joints (like the shoulder or hip), and others. They permit bones to shift relative to one another.
Movable joints
Movable joints are strengthened by _____________, which are pieces oof fibrous tissue that connect bones to one another.
Ligaments
Movable joints consist of a ________________, which encloses the actual joint cavity.
Synovial capsule
Joint cavity is also called _________________.
Articular cavity
A layer of soft tissue called the ______________ secretes synovial fluid, which lubricates the movement of structures in the joint space.
Synovium
The _______________ contributes to the joint by coating the articular surfaces of the bones so that impact is restricted to the lubricated joint cartilage, rather than to the bones.
Articular cartilage
The end of the muscle with a larger attachment to bone (usually the proximal connection) is called the ____________.
Origin
The end with the smaller attachment to bone (usually the distal connection) is called the _____________.
Insertion
Often, our muscles work in ________________; one relaxes while the other contracts. Such is the case in the arm, where the biceps brachia and triceps brachia work antagonistically.
Antagonistic pairs
Muscle can be _______________ - working together to accomplish the same function.
Synergistic
A _____________ muscle decreases the angle across a joint (like the biceps brachii).
Flexor
An ____________ increases or straightens the angle across a joint (like the triceps brachii).
Extensor
An ______________ moves a part of the body away from the midline (like the deltoid).
Abductor
An _____________ moves a part of the body toward the midline (like the pectoralis major).
Adductor
A _________________ rotates the axis of the limb toward the midline (like the subscapularis).
Medial rotator
A _______________ rotates the axis of the limb away from the midline (like the infraspinatus).
Lateral rotator
