A&P 1 Final (Ch. 1 - 10)

Which of the following statements is NOT true regarding ATP production in muscles during periods of prolonged energy use, such as exercise? >Prolonged activity requires the use of aerobic pathways for ATP regeneration. -In the absence of oxygen, anaerobic pathways provide minimal ATP regeneration for less than a minute. -As your blood sugar drops at any time during prolonged activity, glycogen stores in your muscles can be broken down to supply a glucose source. -In the absence of oxygen, creatine phosphate can drive aerobic respiration pathways for a few minutes.

In the absence of oxygen, creatine phosphate can drive aerobic respiration pathways for a few minutes. This is not true for a few reasons. First, creatine phosphate directly phosphorylates ATP instead of providing any support for aerobic pathways. Second, creatine phosphate stores are used up in about 15 seconds. Third, a cell doesn't need an oxygen deficit for creatine phosphate to be activated; it just needs to be short on ATP.

The correct order of events in tissue repair, from first to last, is....

Inflammation, organization, and regeneration

Heart muscles would tend to separate without______

Intercalated discs

What describes the orbicularis oris?

It closes, purses, and protrudes the lips

Why is the rib at B considered a true rib?

It passes from the vertebral column to the sternum via its own costal cartilage. True, or vertebrosternal, ribs make a complete circuit around the thoracic cage in a ring that includes their own costal cartilage.

What must happen before a body cell can begin mitotic cell division?

Its DNA must be replicated exactly so that identical copes of the cell"s genes can be passed on to each of its offspring. Before a body cell begins mitosis, it must replicate its DNA so that each daughter cell will have the same DNA as the parent cell.

A ciliated version of pseudostratified columnar epithelium containing mucus-secreting goblet cells.....

Lines most of the respiratory tract

At an archeological site you discover a bone that is cylindrical in shape, about one inch long and a quarter of an inch wide. What is the correct classification.

Long bone

The dorsal body cavity is the site of which of the following? -intestines -brain -lungs -liver

Brain

What is one difference between bursae and tendon sheaths?

Bursae are flattened fibrous sacs wedged between adjacent structures, while tendon sheaths are elongated fibrous sacs that wrap around tendons.

Pregnant woman experience an extravagant lordosis, or "swayback." Which curvature is affected during pregnancy?

C A diagnosis of lordosis (known as hyperlordosis when it becomes excessive) is based on an exaggerated lumbar curvature.

Which structure in the figure corresponds to a single skeletal muscle cell?

C A skeletal muscle cell is commonly termed a muscle fiber.

Which layer is composed primarily of dense irregular connective tissue?

C Layer C consists primarily of dense, interwoven fibers of collagen designed to resist tearing from any direction.

What protein functions as a motor protein that applies the power stroke during muscle contraction?

C The myosin head groups (C) hydrolyze ATP to power molecular movement along the actin subunits of the thin myofilaments.

The ventral cavity includes which of the indicated subdivisions in the figure?

C, D, and E

In which phase in the figure would the net movement of Ca2+ into the sarcoplasmic reticulum (SR) be greatest?

C. During the period of relaxation (C), Ca2+ is transported by active transport into the SR. Deceased Ca2+ concentrations in the sarcoplasm leads to detachment of cross bridges and, consequently, decreased contractile force.

What structure is a type of sweat gland?

C. Structure C is eccrine gland, the most abundant type of sweat (sudoriferous) gland.

Which of the following would be regarded as an organic molecule? -CO2 -H2O -NaOH -CH4

CH4

Which of the following is most directly required to initiate the coupling of myosin to actin? -Ca++ -ATP -ACh -glucose

Ca++ It binds to troponin, which removes tropomyosin from the myosin binding site on actin.3

Identify the correct sequence of the following events. a. Myosin generates a power stroke. b. Ca++ binds to troponin. c. ATP recharges the myosin head. d. Troponin removes the tropomyosin from G actin. e. The sarcomere shortens. f. Myosin binds to actin.

Ca++ binds to troponin, which removes the tropomyosin from G actin. This allows the myosin binds to actin and generate a power stroke, shortening the sarcomere. ATP is used to recharge the myosin.

What tissues have little to no functional regenerative capacity?

Cardiac muscle and nervous tissue

Which of the following is NOT a functional classification for joints? -diathrosis -synathrosis -amphiarthroses -cartilaginous

Cartilaginous Cartilaginous is a structural classification for joints.

You observe a uniform tissue under a microscope. There is no lumen. The material looks densely packed, but you do not observe many nuclei. It appears that there are strands of fibers running in parallel directions. What type of tissue are you looking at?

Connective tissue You are probably looking at a dense regular connective tissue, which primarily consists Of parallel collagen fibers. All other primary tissues are composed mainly of cells, but connective tissues consist largely of a nonliving extra cellular matrix, which separates, often widely, the living cells of the tissue.

Connective tissues are made of different combinations of ground substance and fibers. As you compare slides of connective tissues, which would most likely be the strongest (toughest) type of connective tissue based on the composition of ground substance and fibers? - Connective tissues high in elastic fibers -Connective tissues high in reticular fibers -Connective tissues high in collagen fibers -Connective tissues high in ground substance

Connective tissues high in collagen fibers Collagen is the toughest of the fibers. If you saw collagen in high amounts, that would indicate strength in the connective tissue.

Cell division would be most common among cells in which of the labeled layers?

D Cells migrate upwards through the epidermis after being generated by mitosis in the stratum basale.

Which step in the figure contains compact bone?

D Osteoblasts in the periosteal layer from compact bone characteristic of the exterior surface of a mature bone

Which of the following is the only bone that normally moves in relation to the others?

D The bone at D forms a joint with the temporal bone (temporomandibular joint) that allows the mouth to open, close, and move laterally.

Which of the labeled parts of the bone is composed primarily of compact bone?

D The shaft of an adult long bone is composed of compact bone.

Which set of membrane proteins in the figure depicts an interaction between two separate cells?

D. Panel D shows recognition of one cell by another via the glycocalyx.

What is the most correct statement regarding nucleic acids? -DNA is long, double-stranded molecule made up of A, T, G, and C bases. -Three forms exist: DNA, RNA, tDNA -tDNA is considered a "molecular slave" of DNA during protein synthesis -RNA is a long, single-stranded molecule made up of the bases A, T, G, and C

DNA is long, double-stranded molecule made up of A, T, G, and C bases.

What is the force driving all of these transport mechanisms?

Diffusion down a concentration gradient Transport by diffusion of a molecule down its concentration gradient is a spontaneous process that requires no energy input.

Which of the following statements is true? -Endocytosis and exocytosis are passive transport mechanisms -During exocytosis, substances from inside the cell are moved outside -Unlike endocytosis, exocytosis does not rely on protein interactions with the plasma membranes -Exocytosis involves infolding of the plasma membrane

During exocytosis, substances from inside the cell are moved outside.

Sudoriferous (sweat) glands are categorized as two distinct types. What are the two types?

Eccrine and apocrine

Which of the following is incorrectly matched? -nucleotide; nucleic acid -elcosanoid; triglyceride -amino acid; protein -monosaccharide; carbohydrate

Elcosanoid; triglyceride

How do endocrine and exocrine glands differ?

Endocrine glands do not use ducts. Endocrine glands secrete substances (hormones) Into blood without the use of ducts, Whereas exocrine glands use ducts To secrete substances into the external environment.

What cell organelle plays a role in the process of regulating intracellular calcium ions for muscle contraction?

Endoplasmic reticulum

Which tissue type consists of a sheet of cells that covers a body surface or lines a body cavity?

Epithelial tissue It is a sheet of cells that covers a body surface or lines a body cavity (epithe = laid on, covering). In addition to covering and linings, epithelial cells can also form glands.

What is a property of epithelial tissue?

Epithelial tissue is innervated, avascular tissue that exhibit polarity. Epithelial tissue is also highly regenerative.

What tissue type has polarity and is avascular?

Epithelium Epithelia have polarity, which is to say that there is directionality. There is always an exposed surface and an attached surface. Epithelia are also avascular.

What process is indicated by C?

Exocytosis of secretory proteins The event indicated by C includes the fusion of secretory vesicle with the plasma membrane and the subsequent release of the vesicle contents to the extracellular space.

Phagocytosis is used by the cells to secrete intracellular substances to the outside cell.

False

True or false: A motor neuron and all the muscle cells that it stimulates are referred to as motor end plate.

False

True or false: Adipose tissue is made up of pseudostratified columnar epithelial cells

False

True or false: All joints permit some degree of movement, even if very slight.

False

True or false: All vertebrae possess a body, a spine, and transverse foramina.

False

True or false: Although all skeletal muscles have different shapes, the fascicle arrangement of each muscle is exactly the same.

False

True or false: Both first- and second-class levers operate at a mechanical disadvantage.

False

True or false: Cartilage has good regenerative capacity, while most epithelial tissues do not.

False

True or false: Cells in the stratum corneum undergo mitosis to keep the layer thick and protective.

False

True or false: Channel mediated diffusion is a form of active transport.

False

True or false: DNA transcription is another word for DNA replication.

False

True or false: During isometric contraction, the energy used appears as movement.

False

True or false: Elastic cartilage tissue is found in the walls of the large arteries that leave the heart.

False

True or false: Epithelial cells contain blood vessels and nerve fibers

False

True or false: In the absence of oxygen, creatine phosphate can drive aerobic respiration pathways for a few minutes.

False

True or false: Intercalated discs and striations are both characteristics of skeletal muscle.

False

True or false: Joe just burned himself on a hot pot, and the burn is quite painful. Joe's burn would best described as third-degree burn.

False

True or false: Lordosis affects the thoracic vertebrae

False

True or false: Nervous tissue consists mainly of neurons and collagen fibers.

False

True or false: Once a motor neuron has fired, all the muscle fibers in a muscle contract.

False

True or false: Short, irregular, and flat bones have medullary cavities in order to keep the weight of the bones light.

False

True or false: The deltoid is a prime mover of the arm that acts in adduction.

False

True or false: The elbow is proximal to the shoulder.

False

True or false: The periosteum is a tissue that serves only to protect the bone because it is not supplied with nerves or blood vessels.

False

True or false: The pituitary bone is housed in a saddle-like depression in the temporal bone called the sella turcica.

False

True or false: The skin is not able to receive stimuli because of the cells of the epidermis are not living and therefore there are no sensory receptors in the skin.

False

True or false: The wrist joint can exhibit adduction and eversion movements.

False

True or false: Triglycerides are a poor source of stored energy.

False

True or false: When a patient is said to have "third-degree burns", this indicates that the patient has burns that cover approximately one-third or more of the body.

False

True or false: A coronal section divides an organ into superior and inferior positions.

False A transverse section divides an organ into superior (top) and inferior (bottom) portions.

True or false: Long bones include all limb bones except the patella.

False Long bones include all limb bones except the patella, tarsals, and carpals.

True or false: Osteons are found in all bone tissues

False Osteons are only found in compact bone; they are absent in spongy bone.

True or false: All muscle cells contain striations

False Smooth muscle cells do not contain striations. Although they do contain mile filament, their arrangement is not regular enough to generate the striations seen in skeletal or cardiac muscle cells.

True or false: The most important factor in joint stability in the depth of the articular surface

False The deeper the articular surface, the more stable the joint, but it seems that the strength of the muscles that cross the joint is the most important factor

True or false: New portions of a nail are produced at the nail bed.

False The nail matrix is the thickened proximal portion of the nail bed responsible for nail growth. The cuticle is the part of the proximal skin fold, or nail fold, that projects onto the nail body.

True or false: Because of its many direct articulations with the axial skeleton, the pectoral girdle is very stable.

False The only bony connection between the pectoral girdle in the thoracic bones is the clavicle. This makes the pectoral girdle very mobile but not very strong.

True or false: ATP is required to cause the power stroke in the myosin head.

False ATP is required to re-cock the myosin head so that it can generate a second power stroke.

True or false: The knee is proximal to the thigh.

False.

What is a bone marking described as a round or oval opening through a bone?

Foramen

What is an example of a positive feedback?

Forming a platelet plug during blood clotting In order to prevent blood loss, the body needs a mechanism that amplifies the action that leads to clotting in a short period of time. This cascade or enhancement of a process is a positive feedback mechanism.

What is a vertical section through the body, dividing it into anterior and posterior regions called?

Frontal

What allows for communication and the passage of small molecules between adjacent cells?

Gap Junction it is a communicating junction between adjacent cells.

Starch is the stored carbohydrate in plants, while ________ is the stored carbohydrate in animals.

Glycogen

What organelle is responsible for processing and packaging proteins destined for export from the cell?

Golgi apparatus

Which of the following is a layer of the epidermis found in thin skin?

Granular layer The upper dermis of thick and thin skin includes a layer called the stratum granulosum, or granular layer. It consist of 4 to 6 cell layers in which kertinocytes appearance changes drastically. It is here that the process of keratinization, in which the cells fill with the protein keratin, begins.

The study of large body structures, visible to the naked eye, such as the heart is called

Gross anatomy

What are the three main components of connective tissue?

Ground Substance, fibers, and cells

Which tissue type likely functions to add support to an organ? -Stratified squamous epithelium -cardiac muscle -Hyaline cartilage -transitional

Hyaline cartilage

A patient voices concern that her normal cholesterol level is dangerous. "I eat no cholesterol at all. That stuff is toxic!" she declares. What is your best response?

"A normal cholesterol level is good thing. Your cells depend on cholesterol to stay healthy, and you can't make vital hormones without it." This patient is clearly interested in maintaining good health, so she may be receptive to accurate information about the positive aspects of the cholesterol on her body's functioning.

Your patient is returning for follow-up 6 weeks after sustaining a non-displaced fracture of his radius. He tells you that his forearm is no longer painful, but he is concerned that he can palpate a "lump" in the bone at the site of the healing fracture. What is your response?

"That bone is a normal part of bone healing at this stage. As your body completes the process, the cells in your bone will gradually remodel it to its previous shape."

Statements about the skeleton

-The appendicular skeleton includes the shoulder girdles -The bones of the limbs makeup the appendicular skeleton -The appendicular skeleton allows us to move around -The axial skeleton supports and protects internal organs

What characterizes proteins?

-They may be denatured or coagulated by heat or acidity -They have both functional and structural roles in the body -Their function depends on their three-dimensional shape

Characteristics of melanoma

-asymmetry -border irregularity -diameter of 12 mm -color that is black or brown

The smallest contractile unit within skeletal muscle would correspond to the distance between which two points in the figure?

1 and 7 The distance between points 1 and 7 spans a sarcomere (the smallest contractile unit of a muscle fiber).

How many bones make up the adult skull?

22

How many lumbar vertebrae are there in a typical adult skeleton?

5 A typical adult skeleton has 5 lumbar vertebrae, 12 thoracic vertebrae, and 7 cervical vertebrae.

The composition of the secretions of the eccrine glands is ________.

99% water, sodium chloride, trace amounts of wastes, and vitamin C

Which joint in the figure is capable of multiaxial movement?

A Ball-and-socket joints, as found in the shoulder and hip, are capable of multiaxial movement in all three planes.

Which letter represents the cervical curvature?

A The cervical curvature includes the first seven vertebrae and is posteriorly concave.

The molecular interaction described as a cross bridge involves the binding of which two proteins?

A and C Cross bridges between thin and thick myofilaments are formed by the specific interaction between actin (A) and myosin head groups (C).

What describes plasma membrane?

A phospholipid bilayer surrounding the cell

Which set of membrane proteins in the figure depicts the transport of solute molecules across the membrane?

A. Panel A shows both passive and active transport processes of solutes mediated by integral membrane proteins.

Which step precedes all of the other listed steps? -Na+ rushes into the cell. -An action potential starts on the sarcolemma. -The sarcoplasmic reticulum is activated. -ACh is released by the motor neuron

ACh is released by the motor neuron. The 1st step toward generating a skeletal muscle contraction is nervous stimulation of the muscle fiber in order to generate an action potential. The site of muscle stimulation, where the nerve ending communicates with the muscle fiber, is called the neuromuscular junction.

What is the primary energy-transferring molecule in cells?

ATP

What is moving a limb away from the midline of the body along the frontal plane called?

Abduction

Which of the following is not a role of connective tissue? -Insulation -Absorption -Transport -Support

Absorption, the movement of substances into the body, is the role of epithelial tissue. Roles of connective tissue include binding and support, protection, insulation, and transportation of substances, via blood, within the body.

What is the difference between active and passive transport across the plasma membrane?

Active transport is ATP dependent, whereas passive transport uses only the kinetic energy of the particles for movement across the plasma membrane.

What is the classification of a solution of NaOH with a pH of 8.3?

Alkaline solution

What describes a bippenate pattern of a fasicicles?

An arrangement in which the fascicles insert into the tendon form opposite sides

Layer B is composed primarily of ______.

Areolar connective tissue The loose connective tissue within the papillary layer of the dermis is rich in blood vessels and cells that function in the body's defenses.

Structures C and D collectively form which of the following? -synovial membrane -ligament -articular capsule -bursae

Articular The synovial membrane and the fibrous layer that covers it collectively form the articular capsule.

Which of the following is the regional term that includes the head? -superior -axial -appendicular -coronal

Axial The axial part of the body, which makes up the main axis of our body, includes the head, neck, and trunk.

Which of the following corresponds to a single fascicle?

B Fascicle is an organized group of muscle fibers (cells).

In which of the labeled parts of the adult long bone would hematopoietic tissue be located?

B Hematopoietic tissue is found in the red bone marrow within certain body locations consisting of spongy bone. Examples include the diploe of flat bones and the proximal epiphyses of the femur and humerus.

Which of the structure in the figure is the primary area of degeneration in osteoarthritis?

B Overuse and normal aging can cause degeneration of the cartilage in joints, leading in osteoarthritis.

Which of the structures is surrounded by the connective tissue sheath known as the perimysium?

B The structure at B is covered by the perimysium. Remember the word root peri means "around," as in the perimeter.

What letter is pointing to an mRNA molecule?

B. Molecule B is a complement of the DNA template (A) and contains ribonucleotides, as indicated by the presence of uracil (U). This is consistent with molecule B being an mRNA molecule.

In which phase of the muscle twitch shown in the figure would the maximum amount of ATP be consumed by the myosin head groups?

B. Myosin heads catalyze the hydrolysis of ATP to power the sliding of myofilaments. This event would be at a maximum during the period of contraction (B).

Your patient is upset to learn that the biopsy of a lesion on her skin is consistent with basal cell carcinoma. She has heard that skin cancer can be deadly. Which response to her distress is most appropriate?

Basal cell carcinoma rarely spreads to other tissues. Removal of the lesion is curative in 99% of cases. Although no one is happy to receive a diagnosis of cancer, basal cell skin cancers are among the least likely to be metastatic or lethal.

Which statement accurately describes the event indicated by B?

Binding of acetylcholine to a receptor triggers the opening of an ion channel. Binding of acetylcholine to a receptor opens chemically (ligand) gated ion channels that allow Na+ and K+ to diffuse across the sarcolemma.

Susan sat out in the sun watching a baseball game. She developed small blisters on her unprotected shoulders and neck. What type of burn is represented by the formation of the blisters?

second-degree burn Second-degree burns injure the epidermis and the superficial region of the dermis. Symptoms mimic those of first-degree burns, but blisters also appear.

Osteoblasts...

secrete osteoid Osteoblasts are the bone-forming cells that produce new bone by secreting the components of the organic matrix, called the osteoid. They also play a role in the calcification of osteoid to form the mature bone matrix.

Which of the following is NOT a normal function of muscle tissue? -stabilizing joints -secreting hormones -mainting posture -producing movement -generating heat

secreting hormones Secreting hormones is a function of the endocrine system.

Cranial nerve II, the optic nerve, sends nerve impulses to the brain carrying information about the things we see. These nerve fibers most likely belong to which division of the nervous system?

sensory (afferent) division

The genetic information is coded in DNA by the...

sequence of the nucleotides

Synovial joints are classified into six main categories based on...

shape of articular surfaces

What joint has most notably sacrificed stability to provide great freedom of movement?

shoulder

Dislocation of a joint is a common orthopedic problem. What joint is MOST likely to be dislocated?

shoulder (glenohumeral) The articulation between the head of the humerus and the glenoid cavity allows for maximum flexibility but sacrifices stability.

What type of muscle requires somatic (voluntary) nervous stimulation for activation?

skeletal

What muscle type has the longest muscle cells and has obvious stripes called striations?

skeletal muscle

Which of the following bones are NOT a part of the appendicular skeleton? -shoulder -upper limb -skull -hip

skull

Reduction in blood flow to a muscle fiber would have the greatest effect on ____________.

slow oxidative fibers

Addition of more mitochondria to a muscle fiber will have the greatest effect on __________.

slow oxidative fibers.

If given the exact same amount of ATP, which of the three fiber types would be able to contract for the longest amount of time?

slow oxidative fivers

Which of the following organelles is correctly paired with its function? -mitochrondrion: packaging proteins and lipids -golgi apparatus: produce energy for the cell -smooth endoplasmic reticulum: metabolism of lipids -lysosome: protein synthesis

smooth endoplasmic reticulum; metabolism of lipids

Nerve impulses leading to the brain carry information about cool temperatures on the skin. The nerve fibers sending these signals will most likely belong to which division of the nervous system?

somatic nervous system

What division of the nervous system is most specifically responsible for voluntary motor control?

somatic nervous system The somatic nervous system is composed of somatic motor nerve fibers that conduct impulses from the CNS to skeletal muscles. It is often referred to as the voluntary nervous system because it allows us to consciously control our skeletal muscle.

The sella turcica is part of the __________ bone and houses the _______ gland.

sphenoid; pituitary

The major head flexor muscles are the _______________.

sternocleidmastoid muscle

Creatine phosphate functions in the muscle by ___________.

storing energy that will be transferred to ADP to resynthesize ATP

Which of the following epithelial tissue types is NOT correctly matched to its function. -stratified squamous epithelium; absorption -simple cuboidal epithelium; secretion -simple squamous epithelium; filtration -simple columnar epithelium with microvilli; absorption

stratified squamous epithelium; absorption Stratified squamous epithelium is thick and durable. It is found in the skin, where it provides protection from the external environment.

The epidermis consists of five layers of cells, each layer with a distinct role to play in the health, well-being, and functioning of the skin. Which of the following layers is responsible for cell division and replacement? -stratum corneum -stratum granulosum -stratum basale -stratum lucidum

stratum basale

What stratum of the epidermis contains the stem cells responsible for regenerating the more superficial layers?

stratum basale The stratum basil is the deepest layer of the epidermis and consists of one layer of actively mitotic stem cells. The stem cells in this layer generate the cells that will migrate to the more superficial layers: spinosum, granulosum, and corneum.

Which of the following terms describes layer D?

subcutaneous The hypodermis ("under the skin") layer is also referred to as the subcutaneous region.

Functions of the skeletal system

support, production of blood cells (hematopoiesis), storage of minerals

Fibrous joint are classified as...

sutures, syndesmosis, and gomphoses

Which of the following are cartilaginous joints? -synchondroses -gomphoses -sutures -syndesmoses

synchondroses

A situation where the bones are connected exclusively by ligaments, cords, or bands of fibrous tissue is a....

syndesmosis

On the basis of structural classification, which is a fibrous joint?

syndesmosis

Which of the following represents a structural classification for joints that are separated by a joint cavity? -synovial -diarthrosis -cartilaginous -fibrous

synovial Structural classification focuses on the material binding the bones together and whether a joint cavity is present.

___________ is a molecule that brings amino acids to the ribosome during translation.

t-RNA Transfer RNA (rRNA) are small, roughly L-shaped molecules that ferry amino acids to the ribosomes.There they decode mRNA's message for the amino acid sequence of the polypeptide to be built, a process called translation.

The RNA responsible for bring the amino acids to the ribosome for protein formation is___________

tRNA

When a sarcomere contracts and thin filaments move over thick filaments you would expect to see _________.

the I bands to appear smaller

What is the major factor controlling how levers work?

the difference in the positioning of the effort, load, and fulcrum

Mitosis is..

the division of the genetic material within the nucleus

The arrow in the figure is pointing to which of the following structures?

the epiphyseal plate During endochondral ossification, a distinct epiphyseal plate is formed at the boundary between primary and secondary ossification centers.

What is the largest, longest, and strongest bone in the body?

the femur Its durable structure reflects the stress exerted on the femur as it bears the wight of the body when standing, walking, or running.

What is intramembranous ossification?

the formation of bone from within fibrous membranes The formation of bone by ossification centers within fibrous membranes is called intramembranous ossification.

Which of the following best describes the process shown in the figure? -bone remodeling in response to changes in mechanical stress -bone repair at a site of fracture -the formation of bone in a membrane -the formation of bone in a preexisting cartilage model

the formation of bone in a membrane

A toxin released by certain bacteria can block the release of neurotransmitters into a neuromuscular synapse. What would result from such a block?

the loss of ability to contract the muscle Without acetylcholine, the muscle would not be able to contract or even maintain tone.

What part of the vertebral column receives the most stress by bearing most of the weight of the body?

the lumbar region

Which of the following would be most associated with process of warming, humidifying, and filtering the air we inhale? -hyoid bone -the cranial bones -the nasal cavity -the bones comprising the orbits

the nasal cavity

Which bone or pair of bones forms the superior portion of the cranium?

the parietal bones

The dermis has two major layers. Which layer constitutes 80% of the dermis and is responsible for the tension lines in the skin?

the reticular layer

What dermal layer is responsible for the dermal properties of skin that are evident as cleavage lines?

the reticular layer The thicker, Deeper layer of the dermis, called the reticular dermis, is named for its network of collagen fibers. These collagen fibers run in various planes, but most run parallel to the skin surface. Separations, or less dense regions, between these bundles form cleavage (tension) lines in the skin.

The contract, or functional, unit of a muscle fiber is ___________.

the sarcomere The sarcomere is the contract our unit of a muscle fiber in the smallest unit of muscle. A sarcomere is the region of a myofibril between two successive Z discs; it primarily consists of thin and thick filaments myofilaments.

The nucleolus is..

the site of ribosomes assembly in a cell

The axial skeleton includes...

the skull, vertebral column, and rib cage

Which of the following is NOT a facial bone? -the maxilla -the nasal bone -the vomer bone -the zygomatic bone -the sphenoid bone

the sphenoid bone It is a cranial bone

Which of the following bones is NOT part of the orbit? -the frontal bone -the temporal bone -the zygomatic bone -the maxilla

the temporal bone The temporal bone is lateral and too fair posterior to contribute to the orbit.

Which of the following would be most associated with housing the special sense organs? -the bones of the inner ear -the temporal bones -hypoid bone -the cranial bones

the temporal bones

What is the main factor that determines the power of a muscle?

the total number of muscle fibers (cells) available for contraction

Which of these is NOT a way of classifying muscles? -muscle shape -the type of muscle fibers -the type of action they cause -muscle location

the type of muscle fibers

Which of the following bones do NOT contain a paired paranasal sinus? -the frontal bones -the zygomatic bones -the sphenoid bones -the ethmoid bones

the zygomatic bones

What feature of the prickle cells in layer C causes them to have pointy projections after tissue preparation?

their desmosome attachment Cells typically shrink during tissue preparation, and since these cells are attached by desmosomes, the membranes are pulled slightly outward at the points of the cellular attachment

if L=Load, F=fulcrum, and E=effort, what type of lever system is described as LEF? -first-class lever -second-class lever -third-class lever -fourth-class lever

third-class lever

To what region of the vertebral column does this vertebra belong?

thoracic Thoracic vertebrae can be identified by the facets on the transverse process and the facets or demifacets on the body used to articulate with ribs.

What are the major functions of the intervertebral discs?

to absorb shock and provide flexibility to the spine

An enzyme known as acetylcholinesterase is present in the synaptic cleft. What is its role?

to break down acetylcholinesterase Acetylcholinesterase breaks acetylcholine apart, terminating the synaptic transmission. Choline can be taken back into the axon terminal and reused.

What is the function of the structure at A?

to lubricate hair and prevent infection Structures A produces sebum, an oily secretion that coats the hairs and prevents infectious agents from penetrating the hair shafting.

What is the function of the cranial bones?

to protect the brain

Which of the these is NOT a function of the layer at D?

to supply cells to replace those lost from the epidermis The hypodermis does not perform this function. Cells to replace those lost in the epidermis are provided by the basal cells of the epidermis itself.

Spongy bone contains...

trabeculae

____________ is a powerful forearm extensor at the elbow joint.

triceps brachii

What is a site for a muscle or ligament attachment?

trochanter It is a type of bone projection; projections often protrude from the bone because of the interaction forced upon them by muscle or ligaments.

The interaction between which protein and ion initiates muscle coupling?

troponin; calcium ions When calcium ions bind to troponin, troponin changes shape and allows tropomyosin to shift away from its inhibitory position. As a result, myosin heads can bind to the actin molecules and begin the cross bridge cycle.

Smooth muscle is

under involuntary control, moves internal organs, cells contain a single nucleus, are spindle-shaped, and do not appear striated; each cell is a fiber Smooth and cardiac is under involuntary. Skeletal is under voluntary control.

Bones do NOT have a role in __________. -blood cell formation -waste removal -support -movement -fat storage

waste removal Waste removal takes place primarily in kidneys.

What are menisci (articular discs)?

wedges of fibrocartilage that partially or completely divide the synovial cavity

Cranial bones develop ________.

within fibrous membranes

What stage of the mitosis do the identical sets of chromosomes line up along the midline or equator of the cell?

Metaphase

Which subdivision of anatomy would include the study of individual cells?

Microscopic anatomy (study of cells, which cannot be seen by the naked eye)

Myocardium (cardiac muscle tissue) must rhythmically contract for a lifetime. This requires a considerable amount of energy production by the cells. You would expect to see a relatively high amount of which organelle in these cells?

Mitochondria

What is the function of the organelle indicated by B?

Modification and packaging of proteins This function is handled by the Golgi apparatus within the endomembrane system; it functions in the sorting and modifying of membrane-bound proteins being transported to various cellular locations.

Passive membrane transport processes include ________.

Movement of a substance down its concentration gradient

If a muscle fiber were to suddenly and permanently stop producing ATP the fiber would no longer be able to actively transport calcium out of the cytoplasm (sarcoplasm) and the intracellular calcium concentration would rise. What do you expect to happen?

Myosin would be able to bind to the exposed binding sites on thin filaments but it would not be able to detach.

If both motor neurons shown in this figure were to develop action potentials and stimulate muscle fibers, would all the muscle cells shown here contract? -No, bc it is impossible for more than one motor unit to contract at once. -Yes, bc signals can be passed from stimulated muscle fibers to unstimulated ones. -Yes, because an entire muscle only needs one neuron to stimulate it in order to contract. -No, bc neurons in this figure do not innervate every muscle shown.

No, bc neurons in this figure do not innervate every muscle shown. Only five muscle fibers shown are innervated. The others would not contract unless they were stimulated by other neurons that are not shown.

Troponin, a major protein in thin filaments, is a globular protein with three polypeptides subunits. Which of the following is NOT a function of the troponin? -One subunit binds to potassium ions. -One subunit attaches troponin to actin. -One subunit binds to calcium ions. -One subunit binds tropomyosin and helps position it on actin.

One subunit binds to potassium ions.

A structure that is composed of two or more tissue types that work together to perform specific functions for the body is an

Organ

Which level of structural organization is considered to be the highest (most complex) level?

Organismal

Which of the following would NOT be restricted (limited) by low levels of ATP? -phagocytosis -pinocytosis -osmosis -exocytosis

Osmosis

For instramembranous ossification to take place, what is necessary?

Ossification centers from in the fibrous connective tissue membrane

Which type of the cell or cellular structure is not found in the epidermis?

Pain receptors Pain receptors formed by free nerve endings are found deep to the upper dermis in the papillary layer of the dermis

The anatomical position is characterized by all the following EXCEPT..... -arms at sides -palms turned posteriorly -thumbs pointed laterally -body erect

Palms turned posteriorly

What is a component of the plasma membrane that creates a physical barrier between the inside and the outside of the cell?

Phospholipids The plasma (cell) membrane is a phospholipid bilayer, composed of two parallel sheets of phospholipid molecules lying tail to tail, with their polar heads exposed to water on either side of the membrane. This allows the plasma membrane to separate the intracellular fluid (the ICF) from the extracellular fluid (ECF).

_____________ Epithelium appears to have two or three layers of cells, but all the cells are in contact with the basement membrane.

Pseudostratified columnar

In a homeostatic control mechanism, which component monitors the environment?

Receptor Homeostasis refers to maintenance of relatively stable internal conditions even though the outside world changes continuously. Receptors monitor changes occurring both inside and outside the body and send this information (called input) to control centers for processing.

An example that illustrates homeostasis maintained by a negative feedback.

Release of sweat by eccrine glands in response to heat.

What joint problems is the result of an autoimmune problem?

Rheumatoid arthitis (RA) In RA, the body's immune system attempts to destroy the tissues in the joints in an apparent case of "mistaken identity."

Molecule B and molecule C are expected to interact within which of the following cellular structures? -Golgi apparatus -nucleus -ribosome -nucleolus

Ribosome The codons within the mRNA (B) are recognized by corresponding tRNA molcules within cytoplasmic ribosomes during protein translation.

What organelle is responsible for synthesizing proteins?

Ribosomes

What is the vertical section through the body, dividing it into left and right, called?

Saggital

What gland secretes sebum, an oily substance?

Sebaceous glands

Which epithelial forms the wall of the air sacs across which gas exchange occurs in the lungs?

Simple squamous

What is a function of the paranasal sinuses?

Sinuses take away a minimal amount of strength from bones while reducing the weight of bones.

What illustrates the fact that skeletal muscle is a voluntary muscle?

Skeletal muscle fibers are innervated by somatic motor neurons.

Under a microscope you observe a tissue that appears to have long fibers that appear striated. The nuclear are pushed off to the side of the fibers. The tissue looks very vascular. What type of tissue are you observing?

Skeletal muscle tissue The striations are in evidence of the male filaments inside skeletal muscles cells, also called muscle fibers. The position of the nuclei And vascularity are also signs of muscle tissue

Which of the following is NOT an example of the same level of structural organization as that represented by image 6?

Smooth muscle

Under your hospitals information portal, your patient reviews the report from her recent biopsy, which includes a reference to "smooth muscle". She asks you if this means her muscles are abnormal. What is the best explanation?

Smooth muscle tissue controls many involuntary functions. Unlike the muscles that control voluntary movement and the heart, it has no "stripes" or striations and so is "smooth."

What layer of the epidermis will be supplied with the highest levels of oxygen from the blood?

Stratum basale

Pigment can be found in several layers of the epidermis. In which layer would you expect to find the cells that produce melanin?

Stratum basale 10-25% Of the cells in the stratum basil are melon and producing cells called melanocytes. They are branching processes extend among the surrounding cells, reaching well into the more superficial stratum spinosum layer.

What function does transitional epithelia have?

Stretching Transitional epithelium is found in the urinary system. It lies the ureters, Bladder, and proximal part of the urethra--Organs that are subjected to the distention or stretching as urine passes through or fills them.

Which of the following correctly describes a common feature of all structures labeled A through D in the figure?

Structures A, B, C, D are located in the dermis.

Which directional term is used to describe the relationship of the skin to the skeletal muscles?

Superficial The skin covers the outside of the body; thus, it is superficial, or external, to the skeletal muscles.

If the figure were used to represent the regulation of body temperature, the structures represented by the letter C would include ______.

Sweat glands in the skin. Effectors in the homeostatic control of body temperature include sweat glands and skeletal muscles.

A red blood cell placed in pure water would...

Swell initially, then shrink as equilibrium is reached

Function of rough endoplasmic reticulum

Synthesis of cellular membrane components Synthesizes all proteins secreted from the cell; also functions the cell's "membrane factory" bc integral proteins and phospholipids that from part of all cellular membranes are manufactured there

What major function occurs on the specific membranes indicated by A? -production of most of the cell's ATP -digestion of food particles -replication of DNA -synthesis of proteins

Synthesis of proteins

Which of the following muscles is named for its action? -biceps brachii -gluteus minimus -frontalis -adductor longus

The adductor longus, located on the medial thigh, brings about thigh adduction.

Which of the following is NOT a factor that contributes to joint stability? -the shape of the articulating surfaces -the amount of synovial fluid in the joint cavity -the number and positioning of reinforcing ligaments -the amount of muscle tone applied to the tendons that cross the joint

The amount of synovial fluid in the joint cavity The amount of synovial fluid in the joint cavity is not a factor that contributes to joint stability. The major role of synovial fluid is to lubricate the joint surfaces of freely movable (synovial) joints.

Which of the following would be an example of the process taking place at B?

The binding of a chemical messenger activating a cytoplasmic enzyme, such as kinase, that leads to specific cellular responses. One activated by the binding of a specific chemical messenger, such as a hormone, the receptor protein initiates cellular responses by activating specific signal transduction pathways.

What is the proper description of the human body in the anatomical position?

The body is erect with feet slightly apart, palms facing forward, and thumbs pointing away from the body.

Which of the following best describes the joint labeled B in the figure? -synarthrotic -fibrous -diarthortic -amphiathrotic

The cartilage joint formed between the first rib and the manubrium is immovable, unlike other rib connections to the sternum.

If cells are placed in a hypotonic solution containing a solute to which the membrane is impermeable, what could happen?

The cells will swell and ultimately burst.

Why is the figure considered to be an example of a negative feedback system, as opposed to a positive feedback system?

The figure illustrates the correction of an imbalance back to a baseline. Negative feedback is what keeps your body systems within a proper working range by reversing trends that move the body away from a set point.

What is the role of the hair matrix?

The hair matrix produces hair. The hair matrix is actively dividing area of the hair bulb that produces hair. As the matrix produces new hair cells, the older part of the hair is pushed upward, and its fused cells became increasingly keratinized and die.

Old age affects many parts of the skeleton. Which of the following is NOT associated with old age? -The vertebrae become more porous and likely to fracture. -The intervertebral discs become thinner and less elastic. The thoracic cage becomes more rigid as costal cartilages ossify. -The mandible continues to grow and thicken.

The mandible continues to grow and thicken. The opposite is true; as the bony tissue of the jaws declines, the jaws (including the mandible) look small and childlike once again.

When the term biceps, triceps, or quadriceps forms part of a muscle's name, what does it tell you about the muscle?

The muscle has two, three, or four origins, respectively.

Based on the relationship between the thick and the thin filaments, what would happen if a disorder that existed that cause a person to produce no tropomyosin?

The muscle tissues would never be able to relax. The tropomyosin covers the myosin binding site on actin. Without tropomyosin, the myosin would constantly have access to those binding sites.

What result would be expected if an additional stimulus, equal in intensity to the first, were to be applied to the muscle at the 60 millisecond (ms) time point?

The muscle would increase in tension to a level greater than that measured at the beginning of phase C. The second, more forceful contraction that would occur by adding another stimulus before the muscle has completely relaxed is an example of wave summation.

Which of the following is not used as a criterion for naming muscles? -The location of the muscle, the nervous system's control the muscle -the locations of the muscle attachments -the shape of the muscle -the number of origins for the muscle

The nervous system's control of the muscle Where did the muscle is controlled by the involuntary or voluntary nervous system is not a criterion used for naming muscles

How are the male and female pelvises different?

The pelvic inlet is heart-shaped in the male. The female pelvic is modified for childbearing; It is wider, shallower, and lighter than the male pelvis. The male pelvis has thicker/heavier bones with more prominent bone markings, acetabula that are larger and closer together, and a narrower, heart-shaped pelvic inlet.

Which of the following statements is FALSE? -The pelvic outlet is narrower in a female than in a male. -The female pelvis is tilted further forward than the male pelvis. -The pubic arch is broader in the pelvis of a female than in the pelvis of a male. -The female pelvis is thinner than that of a male.

The pelvis outlet is narrower in a female than in a male

The best explanation as to why ionic compounds easily dissociate in water?

The polarity of water easily breaks the charges between the oppositely charged ions in the compound.

What is the correct order in which the components interact in a homeostatic control system?

The receptor, the control center, and the effector Regardless of the factor or event being regulated- the variable- all homeostatic control mechanisms are processes involving at least three components that work together. The first component, the receptor, is a sensor that monitors the environment and responds to changes by signaling (providing input to) the control center. The control center compares the input to the set point, which is the level or range at which a variable is to be maintained, and signals the appropriate effector(s). The effector produces the effect (change) that counteracts the initial problem (stimulus).

The 100-meter dash is a quick and short run requiring explosive speed. On completion of the dash, the runners will continue to breathe hard for several seconds to minutes even though they are no longer running. What is the best explanation for this?

The runners' use of stored oxygen, glucose, and creatine phosphate is being replenished in this requires a prolonged increase of oxygen intake

What muscle cell structure stores calcium ions that are used to trigger the contraction?

The sarcoplasmic reticulum It is an intracellular tubule that stores and releases calcium ions.

What's the difference between eccrine sweat glands and apocrine sweat glands?

The secretions of apocrine sweat glands contain more fat and protein than do the secretions of eccrine sweat glands. Compared to the watery secretions of eccrine glands, apocrine swear glands produce a more viscous secretion that is enriched with fats and proteins.

Definition of anatomy

The study of the structure of body parts and their relationships with one another

The dorsal body cavity is divided into which of the following subdivisions?

The vertebral/spinal and cranial cavities The dorsal body cavity, which protects the fragile central nervous system organs, has two subdivisions: the cranial cavity and the vertebral, or spinal cavity.

What bones of the skull would you also refer to as a cheekbone?

The zygomatic bone

Which of these is NOT part of the dorsal cavity? -cranial cavity -thoracic cavity -spinal cord -vertebral cavity

Thoracic cavity

What level of structural organization is represented by the image numbered 5 in the figure? -tissue -organ -cell -organelle

Tissue

What is the result of the negative feedback process?

To maintain homeostasis

True or false: Movement of the ankle so that the superior aspect of the foot approaches the shin is called dorisflexion

True

True or false: Moving a limb so that it describes a cone in space is called circumduction

True

True or false: Muscle power depends mostly on the total number of muscle fibers (cells) in the muscle.

True

True or false: One of the functions of skeletal muscle contraction is production of heat.

True

True or false: Positive mechanisms tend to enhance the original stimulus so that the response is accelerated.

True

True or false: Regardless of type, all levers follow the same basic principle: effort farther than load from fulcrum = mechanical advantage; effort nearer than load to fulcrum = mechanical disadvantage.

True

True or false: Simple cuboidal epithelium are usually found in areas where secretion and absorption occur

True

True or false: Skeletal muscle cells are long and cylindrical with many nuclei.

True

True or false: Squamous cells are flattened and scale-like when mature

True

True or false: Supination is the movement of the forearm in which the palm of the hand is turned anteriorly or superiorly

True

True or false: The acidity of a solution reflects the concentration of free hydrogen ions in the solution.

True

True or false: The amount of movement permitted by a particular joint is the basis for the functional classification of that joint.

True

True or false: The arrangement of a muscle's fascicles determines its range of motion and power.

True

True or false: The dense fibrous connective tissue portion of the skin is located in the reticular region of the dermis

True

True or false: The dermis contains blood vessels and nerve fibers while the epidermis does not.

True

True or false: The femur is the largest and strongest bone in the body.

True

True or false: The force of muscle contraction is controlled by multiple motor unit summation or recruitment.

True

True or false: The ischium articulates with both the ilium and the pubis forming the acetabulum.

True

True or false: The lower the pH, the higher the hydrogen ion concentration.

True

True or false: The pinkish hue of individuals with fair skin is the result of the crimson color of oxygenated hemoglobin (contained in red blood cells) circulating in the dermal capillaries and reflecting through

True

True or false: The protein found in large amounts in the superficial layer of the epidermis cells is keratin.

True

True or false: The shock-absorbing pads between the vertebrae are formed of fibrocartilage.

True

True or false: The skeletal muscle is under voluntary control.

True

True or false: The skin cancer most likely to metastasize is cancer of the melanocytes.

True

True or false: The term osteoid refers to the organic part of the matrix of compact bones without mineralization

True

True or false: There are seven cervical, twelve thoracic, and fiver lumbar vertebrae

True

When a muscle fiber contracts, the I bands diminish in size, the H zones disappear, and the A bands move closer together but do not diminish in length.

True

True or false: The major function of DNA is to provide the genetic instructions for protein synthesis.

True DNA provides the basic instructions for building every protein in the body. RNA carries out the orders for protein synthesis issued by DNA

True or false: During endochondral ossification, hyaline cartilage is broken down and replaced with bone.

True Endochondral ossification is the formation of bone within hyaline cartilage. Beginning late in the second month of development, this process uses hyaline cartilage "bones" formed earlier as models, or patterns, for bone construction. It is more complex than intramembranous ossification because the hyaline cartilage must be broken down as ossification proceeds. Most bones below the base of the skull form by endochondral ossification.

True or false: In the muscles of the limbs, the origins is usually the immobile muscle attachment.

True In the muscles of the limbs, the insertion is pulled toward the immobile origin.

True or false: The collagen fibers of the osteoid makes the overall bone matrix stronger by allowing it to resist bending and twisting forces

True The organic matrix, or osteoid, makes up about 1/3 of the bone matrix. This portion includes the collagen fibers that provide born with his flexibility and tensile strength, allowing it to resist stretch and twisting.

True or false: The anterior compartment of the thigh is involved in lower leg extension.

True The quadriceps group sits in the anterior compartment of the thigh. These muscles extend the lower leg.

True or false: All epithelia have two surfaces, an apical surface and a basal surface, that differ in both structure and function. This property is called polarity.

True All epithelia exhibit polarity, which is defined by the presence of an apical, or free, surface in a basil, or attached, surface that deferred and both structure and function.

True or false: Dense connective tissue is dominated by collagen fibers

True Dense regular connective tissue contains closely packed bundles of collagen fibers running in the same direction, parallel to the direction of pull. This arrangement results in white, flexible structures with great resistance to tension (pulling forces) Where the tension is exerted in a single direction.

True or false: The radius is the lateral bone in the foramen.

True In the anatomical position, the radius would be supinated into the lateral position.

True or false: All salts are ionic compounds, but not all ionic compounds are salts.

True Salts are ionic compounds that contain a cation other than H+ and an anion other than OH-.

True or false: All organic compounds contain carbon except CO2 and CO.

True.

Phospholipids make up most of the lipid part of the cell membrane. Since water exists on both outside and inside of a cell, which of the following phospholipid arrangements makes the most sense?

Two back-to-back phospholipid layers with the polar heads facing out on both sides

Crenation (shrinking) is likely to occur in blood cells immersed in ________.

a hypertonic solution

Most skeletal muscles contain ________.

a mixture of fiber types

Homeostasis is the condition in which the body maintains...

a relatively stable internal environment, within limits

A gene can be best defined as...

a segment of DNA that carries the instructions for one polypeptide chain

Which of the following is NOT an example of a fibrous joint? -a suture -a syndesmosis -a symphysis -a gomphosis

a symphysis A symphysis is a cartilaginous joint, not a fibrous joint.

What type of muscle assists an agonist by causing a like movement or by stabilizing a joint over which an agonist acts?

a synergist

What type of level is exemplified by the flexing of the forearm by the biceps brachii muscle?

a third-class level

Performing "jumping jacks" requires ________.

abduction and adduction

After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction?

acetylcholinesterase breaks apart the ACh

Tendon sheaths..

act as friction-reducing structures

What protein is indicated by the letter A?

actin Actin is the chief component of the thin myofilaments. It is made of a set of globular proteins attached in a chain.

The sliding filament model of contraction involves ___________.

actin and myosin sliding past each other and partially overlapping.

During muscle contraction, myosin cross bridges attach to which active sites?

actin filaments

Which of the following is the major component of the part of the bone labeled E?

adipose tissue Yellow bone marrow within the medullary cavity is composed primarily of adipose tissue (fat).

In connective tissue, the role of elastic fibers is to.....

allow the tissue to stretch and recoil Elastic fibers contain elastin, a rubber like proteins that allows them to stretch and recoil like rubber bands.

Articulations permitting only slight degrees of movement are ________.

amphiarthroses

What is a joint that is slightly movable?

amphiarthroses

What is a muscle that provides the major force for producing a specific movement called?

an agonist (prime mover)

What would be the physical sign that a bone cannot continue longitudinal growth?

an epiphyseal line The epiphyseal plate is a zone of hyaline cartilage between the epiphysis and diaphysis of a long bone. When the cartilage is replaced with bone and the plate closes, the bone has reached its maximum length. The ossified remnant of the "growth plate" is called the epiphyseal line.

The figure represents a wedge-shaped section of which structural unit of bone?

an osteon The circular structural unit found within compact bone is termed the osteon, and consists of a central canal surrounded by layers of bone.

A muscle that opposes, or reverses, a particular movement is a(n) ________.

antagonist

What functional group has the major responsibility for countering a specific movement?

antagonists The antagonist opposes the movement produced by the agonist. It is often responsible for returning a limb to its initial position. Antagonists also adjust the action of their agonists by contracting slightly to provide some resistance, thus helping to prevent overshooting the mark or to slow or stop the movement. Agonist/Antagonist pairs are located on opposite sides of the joints across which they act.

The process of bones increasing in thickness is known as...

appositional growth

During bone growth, which significant event occurs at the surface indicated by the letter C?

appositional growth Growth in width involves the adding of layers of lamellar (compact) bone along the bone's outer surface. This process of growth by "layering" is termed appositional growth and is distinct from growth by expansion of the interior matrix (interstitial growth).

Synarthrotic joints..

are immovable joints

Which vertebra does not have a body? -last lumbar -axis -atlas -last cervical

atlas

A splinter penetrated into the skin of the sole of the foot, almost to the papillary region of the dermis. Which layer of the epidermis would be the final layer injured?

basale

The pH scale is...

based on the concentration of hydrogen ions in a solution The pH scale, which ranges from 0 to 14, is a logarithmic scale based on the concentration of hydrogen ions in a solution.

Which of the following is NOT found in cartilage but is found in bone? -living cells -blood vessels -lacunae -organic fibers

blood vessels

The central (Haversian) canal that runs through the core of each osteon is the site of ________.

blood vessels and nerve fibers

What tissue has lacunae, calcium salts, and blood vessels?

bone (osseous tissue)

Which structure is seen at the arrow?

bone collar A collar of ossified tissue forms around the bone in the early stages of ossification.

What is a feature of synovial joints?

bone ends covered with hyaline cartilage Glassy-smooth hyaline cartilage covers the opposing bone surfaces as articular cartilage. These thin but spongy cushions absorb compression placed on the synovial joint and thereby keep the bone ends from being crushed.

The primary function of the deep muscles of the thorax, such as the intercostals, is to promote ________.

breathing. The deep muscles of the thorax, like the internal and external intercostals and the diaphragm, promote movements necessary for breathing.

Connective tissue sacs lined with synovial membrane that act as cushions in places where friction develops are called...

bursae

In the epiphyseal plate, cartilage grows...

by pushing the epiphysis away from the diaphysis

Saddle joints have concave and convex surfaces. Identify the saddle joint of the skeleton.

carpometacarpal joint of the thumb

What tissue forms the model for endochondrial ossification?

cartilage

Synchondroses and symphyses are examples of ______ joints.

cartilaginous

A joint held together by fibrocartilage would be classified as a _______ joint.

cartilaginous Cartilaginous joints are held together by cartilage. Fibrocartilage holds together symphyses.

What term best categorizes the joints in the figure?

cartilaginous joints All of these joints are composed primarily of cartilage

What defines synchondroses?

cartilaginous joints where hyaline cartilage unites the ends of bones

The blood vessels and nerve in the figure are found within which type of space?

central (or Haversian) canal runs lengthwise at the center of each section.

In an isotonic contraction, the muscle ________.

changes in length and moves the "load"

Three types of skin barriers

chemical, physical, biological

What event at letter B leads to the elongation of the bone?

chondrocyte hypertrophy and deterioration Cell division of chondrocytes occur on the epiphysis facing side. Rather than dividing, here chondrocytes hypertrophy and deteriorate along the diaphyseal surface of the growth surface.

The fiber type that gives connective tissue great tensile strength is ________.

collagen

The reason that intervertebral discs exhibit a large amount of tensile strength, which allows them to absorb shock, is because they possess ________.

collagen fibers

Which of the following are correctly matched? -compound fracture; the fractured bone ends penetrate the skin -nondisplaced fracture; the fractured bone ends are misaligned -incomplete fracture; the bone is broken through -linear fracture; the break is perpendicular to the bone's long axis

compound fracture; the fractured bone ends penetrate the skin Such open injuries carry a higher risk of infection.

The ability of muscle to shorten forcibly when adequately stimulated is known as ________, and sets muscle apart from other tissue types.

contractility

Which of the following are correctly matched? -parallel arrangement of fascicles -circular arrangement of fascicles; describes the deltoid muscle -convergent arrangement of fascicles; fan-shaped muscle -pennate arrangement of fascicles; spindle-shaped muscle

convergent arrangement of fascicles; fan-shaped muscle A convergent muscle has a broad origin, and its fascicles converge toward a single tendon of insertion. Such a muscle is triangular or fan shaped like the pectoralis major muscle of the anterior thorax.

A needle would pierce the upper dermis layers of the forearm and what order?

corneum, granulosum, spinosum, basale

Thoracic vertebrae differ from the other vertebrae in that they have....

costal facets

During concussion (a type of traumatic brain injury) the brain will move within the cranial cavity. Damage is caused to the brain as it crashes into part of the bony cavity walls. Ironically one of the bone markings that can cause serious damage to the brain is the _______. This is ironic because one of the functions of this bone marking is to ________.

crista galli; attach to and support the hyoid bone

What names the three main parts of a human cell?

cytoplasm, plasma membrane, and nucleus

What is the structure indicated by label E?

dermal papilla

Layers B and C collectively form the __________.

dermis Although layers B and C can be distinguished based on their structural components, they form a continuous layer of the skin termed the dermis

What is the function of the structure B?

detection of pressure stimulus Structure B is a lamellar (Pacinian) corpuscle that responds to the cutaneous contacts involving deep pressure

A fracture in the shaft of a bone would be a break in the....

diaphysis

Lifting up a glass to take a drink involves the elbow joint. Which of the following correctly characterizes that joint? -diarthrotic -cartilaginous -pivot -biaxial

diarthrotic

Which of the following terms describes the range of movement of the illustrated joint? -synovial -diarthrotic -synathrotic -amphiarthrotic

diarthrotic Synovial joints are considered to be freely movable and are therefore described as diathrotic.

What event directly triggers the release of neurotransmitter from the synaptic vesicle in the axon terminal

diffusion of Ca2+ into the axon terminal A nerve impulse arrives at the axon terminal triggering the opening of Ca2+ channels, which allows for the diffusion of Ca2+ into the terminal. This in turn leads directly to the release of neurotransmitters by exocytosis.

The sliding filament model of contraction states that ________

during contraction, the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments overlap to a greater degree The sliding filament model of contraction states that during contraction, the thin myofilaments slide past the thick myofilaments so that actin and myosin filaments overlap to a greater degree. In a relaxed muscle fiber, the thick and think myofilaments overlap only at the ends of the A band.

A muscle that is lengthening while it produces tension is performing a(n) ____________ contraction.

eccentric During isotonic, eccentric contractions, muscle lengths as it generates tension, but not enough force, to overcome the load. We use eccentric contractions to lower objects (such as lowering a book from the shelf or lowering the barbell during a bench press).

You are asked to classify an exocrine gland found in the skin based solely on the chemical analysis of its product, which turns out to be a hypotonic fluid consisting of about 99% water with a pH of 5. It contains NaCl, traces of urea and ammonia, and a peptide called dermcidin, but lacks fats and proteins. How would you classify this gland?

eccrine gland

The shape of the external ear is maintained by ________.

elastic cartilage

What bone forming process is shown in the figure?

endochondral ossification The figure illustrates a step in the embryonic formation of a bone from a cartilage model.

Glands, such as the thyroid, that secrete their products directly into the blood rather than through ducts are classified as....

endocrine

What surrounds an individual muscle cell?

endomysium

What is the functional role of the T tubules?

enhance cellular communication during muscle contraction

Which layer of tissue is damaged in a first-degree burn?

epidermis

What structure allows the diaphysis of the bone to increase in length until early childhood?

epiphyseal plate

What is implicated in osteoporosis in older women?

estrogen deficiency due to menopause

What property is most directly associated with changes to a muscle cells membrane potential (the voltage across the plasma membrane)?

excitability Excitability, also termed responsiveness, is the ability of a cell to receive and respond to a stimulus by changing its membrane potential. For example, a neurotransmitter released by nerve cell because the deep polarization of the muscle cell's sarcolemma.

What cellular event is indicated by A?

exocytosis Neurotransmitters stored in synaptic vesicles are released into the synaptic cleft by exocytosis.

Exhaustion of glycogen storage within a muscle fiber would have the biggest effect on ________.

fast glycolytic fibers

The terms inversion and eversion pertain only to the...

feet

The pelvic girdle does NOT include the... -femur -ischium -ilium -pubis

femur

What material is found in C and D that is not found in A and B?

fibrocartilage Fibrocartilage forms part of the articular materials on the bones shown in C and D, but it is not found in A and B.

After a heart attack, fibrosis occurs at the site of cardiac muscle cell death. This reduces the efficiency of the heart's pumping activity because __________.

fibrous connective tissue is incapable of contracting Cardiac muscle contains sarcomeres, which allow for the tissue to contract when electrically stimulated. Fibrous connective tissue lacks these special contractile units.

What type of joint is suture?

fibrous joint Sutures are classified structurally as fibrous joints. They would be classified functionally as synarthrotic joints based upon their degree of movement.

All three joints in the figure are classified as ______.

fibrous joints In all three joints, bones are directly connected by dense fibrous tissue to form a joint lacking a cavity.

What is the function of the external oblique muscles?

flex vertebral column and compress abdominal wall

What is the most specific term you could apply to the rib at D?

floating rib This is a floating rib because it does not articulate with a costal cartilage and instead terminates in the body wall.

What is the first stage in the healing of a bone structure?

formation of a hematoma In order, here are the stages of bone fracture healing: (1) formation of a hematoma, (2) formation of a fibrocartilaginous callus, (3) formation of a bony callus, and (4) bone remodeling.

What bone forms the anterior cranium?

frontal bone

Curvatures of the spine serve the body by ________.

giving additional springiness and flexibility to the spine which absorbs shock

Which type of movement does not occur at the shoulder joint?

gliding Gliding occurs when two bones slide across one another, such as in the intercarpal joints.

Which of the following muscles is named for its size? -trapezius -deltoid -gluteus maximus -sternocleidomastoid

gluteus maximus The term maximus indicates the size of its muscle; gluteus maximus is the largest of the gluteus muscles. Additionally, gluteal is the name of the region where the muscle is located.

An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is ________.

glycolysis

Growth of bones is controlled by a symphony of hormones. Which hormone is important for bone growth during infancy and childhood?

growth hormone

What is the most important stimulus for epiphyseal plate activity during infancy and childhood?

growth hormone

During infancy and childhood, the most important stimulus of epiphyseal plate activity is ________.

growth hormone During infancy and childhood, the single most important stimulus for bone growth is growth hormone. It directly stimulates growth of the hyaline cartilage that forms the epiphyseal plates in long bones, causing the bones to lengthen.

The correct order (from start to finish) of fracture repair is....

hematoma formation, soft callus formation, bony callus formation, and bone remodeling

Presence of a synovial cavity, articular cartilage, synovial membrane, and ligaments are characteristics of what type of joint?

hinge joint

What kind of tissue is the forerunner of long bones in the embryo?

hyaline cartilage

The area where blood vessels are penetrating the center of the bone used to be occupied by which tissue?

hyaline cartilage In this type of ossification, the bone is first modeled from cartilage and then replaced by bone as blood vessels invade the model.

What material makes up most of the structure at A?

hyaline cartilage The articular cartilage at the ends of long bones is formed from hyaline caritlage.

The ________ is the only bone in the body that does not directly articulate with any other bone.

hyoid bone The hyoid bone does not articulate directly with any other bone. Instead, it is anchored by the stylohyoid ligaments to the styloid process of the temporal bones.

Apocrine glands, which begin to function at puberty under hormonal influence, seem to play little role in thermoregulation. Where would we find these glands in the human body?

in the axillary and anogenital area

First-class levers _________.

in the body can operate at a mechanical advantage or mechanical disadvantage, depending on specific location.

Lengthwise, long bone growth during infancy and youth is exclusively through ________.

interstitial growth of the epiphyseal plates

Ossification of the ends of long bones....

is produced by secondary ossification centers

The hyoid bone is unique because it.....

is the only bone of the body that does not articulate with any other bone

What is the most common cell type in the dermis?

keratinocytes They are primarily cells that form the stratified layers of the epidermis

During vigorous exercise, there may be insufficient oxygen available to completely break down pyruvic acid for energy. As a result, the pyruvic acid is converted to ________.

lactic acid

What is the term for the layers of bony matrix surrounding the vessels and nerve?

lamellae Lamellae are layers of bony matrix synthesized by osteoblasts during bone growth and maintenance.

What is the correct order for the phases of a muscle twitch?

latent, contraction, relaxation

Both molecule A and molecule B are classified as _______________

lipids Triglycerides and phospholipids are two of the three major types of lipids.

What is a factor that affects the velocity and duration of a muscle contraction?

load on the fiber

What influences the velocity and duration of muscle contraction?

load placed on the muscle Speed (velocity) of shortening is a function of load and muscle-fiber type. Contraction is fastest when the load on the muscle is zero; a greater load results in a slower contraction and a shorter duration of contraction.

What is the abnormal curve often seen in pregnant women as they attempt to preserve their center of gravity toward the end of the pregnancy?

lordosis

Which vertebrae would you expect to have the largest body, relative to the other regions? -thoracic -sacral -cervical -lumbar

lumbar

Which of the following pairs is correctly matched? -cervical vertebrae; rib facets -thoracic vertebrae; transverse foramen -lumbar vertebrae; short, flat spinous processes -lumbar vertebrae; bifid spinous processes -thoracic vertebrae; triangular vertebral foramen

lumbar vertebrae; short, flat spinous processes The lumbar vertebrae have large, flat and spinous processes as a result of being attached to the large muscles in the back.

The __________ is the main chewing muscle

masseter

Paranasal sinuses are found in which of these facial bones? -maxillae -nasal conchae -zygomatic bones -vomer

maxillae

Which skin pigment is made in the skin as a natural defense against UV radiation?

melanin Melanin is the only one of the three pigments (melanin, carotene, and hemoglobin) that contribute to skin color that is actually produced in the skin itself. Melon and protects the DNA of skin cells from UV radiation by absorbing the rays and dissipating the energy as heat.

Which skin-color-associated, pigment-producing cell is located in the labeled layer D?

melanocyte

The most dangerous type of skin cancer_____.

melanoma Melanoma, cancer of melanocytes, is the most dangerous skin cancer because it is highly metastatic and resistant to chemotherapy. These cancers appear spontaneously, and about one-third develop from preexisting moles.

What part of the sarcolemma contains acetylcholine receptors?

motor end plate

What describes the ANS?

motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands

What is the correct sequence of events in cellular respiration?

motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments

Each neuron shown in this figure innervates a group of muscle fibers. What is the term for a group of muscle fibers innervated by a single neuron?

motor unit A group of muscle fibers innervated by a single neuron is called a motor unit.

The hip joint is a good example of a ______ synovial joint.

multiaxial

Which of the following are correctly paired? -unaxial joint; permits only slipping or gliding movements -biaxial joint; permits movement in one plane and around one axis -multiaxial movement; movement in all three planes and around all three axes -nonaxial movement; no movement

multiaxial movement; movement in all three planes and around all three axes

During development embryonic cells will fuse to form muscle fibers. This will result in __________.

multinucleated muscle fibers that can extend as long as 30 centimeters

After DNA replication is completed, what does each DNA double helix consist of?

one old template strand and one new daughter strand This mechanism is called semiconservative replication and is based on the ability of each strand of the DNA double helix to function as a template for the synthesis of the opposite strand.

The thumb joint is indicated by D allows which of the following special movements? -elevation -opposition -inversion -dorisflexion

opposition It is the movement that allows the touching of the thumb to the tip of each finger.

When you bring any of your fingers in contact with your thumb, this movement is called __________.

opposition The saddle joint between metacarpal I of the thumb and the trapezium allows a movement called opposition-- the action taken when you touch your thumb to the tips of the other fingers on the same hand. It is opposition that makes the human hand such a fine tool for grasping and manipulating objects.

The cell responsible for secreting the matrix of bone is the ________.

osteoblast

What cell is seen at the arrow in image A?

osteoblasts Osteoblasts ("bone makers") begin bone formation by secreting the bone matrix.

Bones are constantly undergoing resorption (breaking bone down) for various reasons. What cell accomplishes this process?

osteoclast

A homeostatic imbalance that activates these bone cells would lead to a loss of bone density.

osteoclasts Osteoclasts are the bone cells that break down bone. If they were activated more than normal, you should expect to see bone loss.

When an osteoblast becomes completely surrounded by its own matrix secretions it is referred to as an ________.

osteocyte

What type of cell is shown at A?

osteocyte Osteocytes, literally "bone cells," are the primary structural and maintenance cells found in bone.

Which of the following cells are NOT matched with its appropriate function? -bone lining cells; maintain bone matrix -osteocytes; bone resorption -osteoblasts; create new bone matrix -osteocytes; produce new bone cells.

osteocytes; produce new bone cells. Osteocytes are mature bone cells that monitor and repair mature bone tissues.

What is the structural unit of compact bone?

osteon Osteon is an elongated cylinder oriented parallel to the long axis of the bone.

Which of the following is a characteristic of the bone material at D not NOT of the material at B? -lamellae -osteocytes -osteons -an origin in mesenchyme

osteons The compact bone at D contains osteons. The spongy bone at B contains trabeculae but no osteons.

What is a bone disorder found most often in the aged and resulting in the bones becoming porous and light?

osteoporosis Osteoporosis refers to groups of disease is in which bone resorption outpaces bone deposit. The bones become fragile and easily fractured. The composition of the matrix remains normal, but bone mass declines, and the bones become porous and light. Osteoporosis occurs most often in post menopausal women.

The periosteum is secured to the underlying bone by....

perforating (Sharpey's) fibers

Which of the following correctly pairs the structure at C with its primary component?

periosteum; dense irregular connective tissue The periosteum is composed of dense irregular connective tissue along with a layer of simple squamous epithelium.

A cell engulfing a relatively large particle will likely utilize ________.

phagocytes

Molecule A is a _________

phospholipid Phospholipid consist of a glycerol backbone linked to two fatty acid chains and a phosphorus-containing group.

If a cell is non-selectively engulfing samples of extracellular fluid, for example to absorb nutrients, it will likely utilize ________.

pinocytosis

Pointing the toes is an example of ________.

plantar flexion

Positive feedback differs from negative feedback because.....

positive feedback tends to enhance the triggering stimulus while negative feedback tends to return the body to a homeostatic balance or "ideal" level

What are the levers that operate at a mechanical advantage called?

power levers

Cells of the stratum spinosum have many interlocking desmosomes that will remain between the cells as they migrate to the stratum corneum. These cell junctions serve the body by ________.

preventing mechanical stress or trauma from damaging the epidermis

Approximately 80% of a muscle fiber's volume are the myofibrils. This characteristic reflects muscles ability to ________.

produce movement through contractile force

What type of movement is unique to the forearm?

pronation Supination and pronation are unique to the forearm because of the arrangement of the radius and ulna. This allows rotation of our hand in space.

Moving your jaw forward, causing an underbite, is called ________.

protraction

What is the major function of the axial skeleton?

provide central support for the body and protect internal organs

Which of the following movements demonstrates a first-class lever? -lifting a rock with your right hand and arm -flexing your knee to raise your heel toward your buttocks -raising your head up off your chest -standing on your toes

raising your head up off your chest Raising your head up off your chest demonstrates a first-class lever. The posterior neck muscles provide the effort, the atlanto-occipital joint is the fulcrum, and the weight to be lifted is the facial skeleton.

Some of the nerve endings in the skin are sensitive to changes in temperature. They are part of a negative feedback mechanism regulating body temperature. These nerve endings represent a(n) ________ in the negative feedback mechanism.

receptor

Which of the following are correctly matched? -brevis; long -transverse; parallel to the long axis -rectus; straight -deltoid; at a right angle to the long axis

rectus; straight Rectus means "straight."

When a muscle is unable to respond to stimuli temporarily, it is in which period?

refractory period

What event triggers the subsequent steps of excitation-contraction coupling?

release of acetylcholine from axon terminals at the neuromuscular junction. It is an event that precedes excitation-contraction coupling. Binding of acetylcholine to receptors in the motor end plate triggers an action potential that propagates along the sarcolemma and into the cell interior via T tubules.

Which of the following structures is common only to only one region of the spinal column? -transverse processes -superior articulating surfaces -rib facets -pedicles

rib facets Rib facets are only found on thoracic vertebrae

Which of the following movements does NOT increase or decrease the angel between bones? -abduction -rotation -circumduction -extension

rotation

The _________ shorten(s) during muscle contraction.

sarcomere As actin slides over myosin, the z lines are pulled closer together, shortening the sarcomere.

What structure in skeletal muscle cells functions in calcium storage?

sarcoplasmic reticulum

Which of the following is correctly matched? -kyphosis; accentuated lumbar curvature -scoliosis; abnormal lateral curvature -herniated disc; dorsally exaggerated thoracic curvature -lordosis; rupture of the anulus fibrosus

scoliosis; abnormal lateral curvature Scoliosis is an abnormal lateral curvature that occurs most often in the thoracic region of the vertebral column.

Which glands secrete an oily product that softens the skin and hair?

sebaceous glands Sebaceous glands secrete an oily substance called sebum. Sebum softens and lubricates the hair and skin, slows water loss from the skin when external humidity is low, and has bactericidal properties.

True or false of connective tissue: Collagen fibers provides high tensile strength

True

True or false: A ball-and-socket joint is a multiaxial joint

True

True or false: A contraction in which the muscle does not shorten but its tension increases is called isometric contraction.

True

True or false: A skeletal muscle contracts with varying force and length of time in response to the body's needs at the time.

True

True or false: A smooth muscle cell has a central nucleus but lack striations.

True

True or false: A tissue consists of groups of similar cells that have a common function.

True

True or false: A wheelbarrow is a good example of a second-class lever.

True

True or false: ATP is unstable, high-energy molecule that provides body cells with a form of energy that is immediately usable.

True

True or false: All synovial joints are freely movable.

True

True or false: An increase in the calcium ion level in the sarcoplasm starts in the sliding of the thin filaments. When the level of calcium ions declines, sliding stops.

True

True or false: An osteon contains osteocytes, lamellae, and a central canal, and is found in compact bone only

True

True or false: Bending of the tip of the finger exhibits flexion.

True

True or false: Blood is considered a type of connective tissue

True

True or false: Bones of the face are a part of the axial skeleton

True

True or false: Costal cartilages join most ribs to the sternum.

True

True or false: Dividing cells must pass through the phases of mitosis in the following order: Prophase, Metaphase, Anaphase, and Telophase.

True

True or false: Each daughter cell resulting from mitotic cell division has exactly the same genetic composition.

True

True or false: Epithelial tissues always exhibit polarity; that is, they have a free surface and a basal surface

True

True or false: Excitability is the ability of a cell to receive and respond to stimulus by charging its membrane potential.

True

True or false: For a doctor, simply looking at a patient's skin can help in making a diagnosis.

True

True or false: Functions of connective tissues include binding, support, insulation, and protection

True

True or false: Gliding movements occur at the intercarpal and intertarsal joints.

True

True or false: Gliding movements occur when one flat, or nearly flat, bone surface glides or slips over another

True

True or false: Glucose is an example of a monosaccharide.

True

True or false: Glycogen, the storage form of glucose, is primarily stored in the skeletal muscle and liver cells.

True

True or false: Hinge joints permit movement in only one plane.

True

True or false: In the anatomical position, the lateral foramen bone in the radius.

True

True or false: Interstitial fluid represents one type of extracellular material.

True

True or false: Lysosomes perform digestive functions within a cell.

True

True or false: Melanomas are rare but must be removed quickly to prevent them from metastasizing.

True

True or false: Movement at the hip joint does not have as wide a range of motion as at the shoulder joint.

True

What protein is indicated by the letter E?

myosin Myosin tail groups form the extended regions of the thick myofilament.

The vomer and ethmoid bones form part of the....

nasal septum The vomer and ethmoid bones form the bony parts of the nasal septum. The vomer forms the inferior portion of the septum. The perpendicular plate of the ethmoid bone forms the superior portion of the septum.

Rigor mortis occurs because ________.

no ATP is available to release attached actin and myosin molecules

What is the most atypical connective tissue since it neither connect structures nor provide structural support?

Blood Blood, the fluid connective tissue within blood Vessels, is the most atypical connective tissue. It does not act as a binding or packing material; it does not provide structural support. It is classified as a connective tissue only because it provides from mesenchyme and Consist of blood cells surrounded by an extra cellular fluid matrix (blood plasma).

The body cavities that protect the nervous system are located in the _______ cavity? -vertebral -dorsal -thoracic -cranial -ventral

Dorsal

...

Stratified epithelium are present where protection from abrasion is important

A many-layered epithelium with cuboidal basal cells and flat cells at its surface would be classified as....

Stratified squamous

What processes allows for the production of molecule B from a template consisting of molecule A?

Transcription It is the synthesis of RNA using DNA as a template.

What bone marking type would likely increase in size when a weight lifter repeatedly exercises muscles that attach to it

Trochanter

What is the role of tropomyosin in skeletal muscles?

Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules

What term best identifies a muscle cell?

muscle fiber Skeletal muscle cells fuse during development to from the mature, multinucleated muscle fibers.

The contractile units of skeletal muscles are ____________.

myofibrils