Assignment 3 (Ch. 6 and part of Ch. 10) Flashcards
Which of the following is a function of the skeletal system?
-blood cell production
-body support
-protection of internal organs
-calcium homeostasis
-all of the above
All of the above
Bones that have complex shapes are….
-long bones
-flat bones
-sesamoid bones
-short bones
-irregular bones
Irregular bones
Bones that have thin parallel surfaces are…
-long bones
-flat bones
-sesamoid bones
-short bones
-irregular bones
Flat bones
The organic component of the matrix in developing or repairing bone is called…
-osteon
-mesenchymal tissue
-hydroxyapatite
-calcium phosphate
-osteoid
Osteoid
Where is spongy bone found in long bones? Where is spongy bone found in flat bones?
-epiphyses; metaphyses
-epiphyses; between the compact bone layers
-metaphyses; between the compact bone layers
-between the compact bone layers; medullary cavity
-diaphysis; between the compact bone layers
Epiphyses; between the compact bone layers
Spongy bone contains an open meshwork of osseous spicules called ____.
-trabeculae
-concentric lamellae
-osteons
-lacunae
Trabeculae
Cells that secrete protein fibers in bone are called ____.
-osteoclasts
-osteoblasts
-osteogenic cells
-osteolytic cells
-osteocytes
Osteoblasts
Cells that free calcium from bone to maintain blood calcium levels are called _____.
-osteoclasts
-osteogenics
-osteolytics
-osteocytes
-osteoblasts
Osteoclasts
Blood is distributed from the surface of a bone to deeper central canals through channels known as _____.
-concentric ducts
-canaliculi
-perforating canals
-concentric cancals
-interstitial canals
Perforating canals
Which statement is true regarding calcium in bone matrix?
-Calcium provides flexibility to the bone matrix.
-Calcium is the organic part of the matrix.
-Calcium is secreted by osteoblasts into the matrix.
-Once deposited, calcium cannot be removed from bone.
-Calcium is found in crystals called hydroxyapatite.
Calcium is found in crystals called hydroxyapatite.
Canaliculi are …
-narrow passageways in the matrix connecting lacunae to blood supply.
-also known as Volkmann’s channels.
-have both a fibrous outer layer and a cellular inner layer.
-the same as Haversian canals.
-layers of bony matrix laid down in rings.
Narrow passageways in the matrix connecting lacunae to blood supply
The lacunae of osseous tissue contain…
-chondroblasts
-blood cells
-bone marrow
-osteocytes
-capillaries
Osteocytes
How would removing hydroxyapatite from bone matrix affect the physical properties of a bone?
-The bone would be more compressible
-The bone would be more brittle
-The bone would be stronger.
-The bone would be less flexible.
-The bone would be more flexible.
The bone would be more flexible
In relationship to the diaphysis of a long bone, the osteons are
-proximal.
-diagonal.
-parallel.
-anterior.
-radial.
Parallel
The type of bone that is adapted to withstand stresses that arrive from many directions is ________ bone.
-irregular
-spongy
-lamellar
-compact
-osteon
Spongy
What are the three ways in which lamellae are organized in compact bone? (Figure 6-7)
-concentrically around an osteon, vertically between osteons, and parallel around the entire bone
-horizontally around an osteon, vertically between osteons, and transversely around the entire bone
-concentrically around an osteon, vertically between osteons, and transversely around the entire bone
-concentrically around an osteon, interstitially between osteons, and circumferentially around the entire bone
-vertically around an osteon, interstitially between osteons, and horizontally around the entire bone
concentrically around an osteon, interstitially between osteons, and circumferentially around the entire bone
When cartilage is produced at the epiphyseal side of the metaphysis at the same rate as bone is deposited on the opposite side, bones
-become shorter
-grow wider
-grow longer
-become thicker
-become more porous and weaker
grow longer
The articular cartilage of a typical long bone is composed of what type of cartilage?
-synovial cartilage
-osseous cartilage
-elastic cartilage
-fibrocartilage
-hyaline cartilage
Hyaline cartilage
What type of tissue is replaced in the embryo during endochondral ossification?
-Wharton’s jelly
-fibrocartilage
-mesenchymal tissue
-hyaline cartilage
-connective tissue membranes
Hyaline cartilage
In normal adult bones,
-osteoblast activity exceeds osteoclast activity, once bone has been formed.
-osteoclasts continue to be active long after osteoblast activity ceases.
-there is no turnover of minerals.
-a portion of the protein and mineral content is replaced each year.
-exercise will have no effect on bone remodeling.
A portion of the protein and mineral content is replaced each year
Select the correct words for the following sentence: The (endosteum/periosteum) covers the superficial layer of compact bone and is made up of (the fibrous and cellular layers/osteoblasts, osteoclasts, and osteocytes). (Figure 6-10)
-endosteum and periosteum; osteoblasts, osteoclasts, and osteocytes
-periosteum; fibrous and cellular layers
-endosteum; fibrous and cellular layers
-endosteum; osteoblasts, osteoclasts, and osteocytes
-periosteum; osteoblasts, osteoclasts, and osteocytes
Periosteum; fibrous and cellular layers
What structure is necessary for a bone to grow in length?
-diaphysis
-epiphyseal cartilage
-periosteal bud
-circumferential lamellae
Epiphyseal cartilage
How is vitamin D (vitamin D3) related to calcium homeostasis in bone?
-Vitamin D is produced by osteoblasts during endochondral ossification.
-Vitamin D is regulated by osteoclast activity.
-Vitamin D is involved in calcium absorption by the digestive tract.
-Vitamin D provides a framework for calcium in the matrix.
-Vitamin D replaces calcium in the skeleton.
Vitamin D is involved in calcium absorption by the digestive tract.
Calcitonin causes what response in the kidneys?
-inhibited osteoclast activity
-increased rate of calcium uptake by the kidney
-elimination of calcium ions into the urine
-increased release of calcitriol by the kidney
Elimination of calcium ions into the urine
Which hormone increases blood calcium upon secretion?
-calcitonin
-parathyroid hormone (PTH)
-growth hormone
-estrogen
Parathyroid hormone (PTH)
The disease osteomalacia causes calcium loss from the skeleton, which would result in bones that are
-more resistant to compression.
-weaker and more brittle.
-stronger and heavier.
-stronger and contain more spongy bone.
-weaker and more flexible.
weaker and more flexible
Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly specialized for
-conduction
-contraction
-cushioning
-secretion
-peristalsis
Contraction
Which of the following is a recognized function of skeletal muscle?
-produce movement
-maintain posture
-guard body entrances and exits
-maintain body temperature
-All of the answers are correct
All of the answers are correct
A fascicle is a
-layer of connective tissue that separates muscle from skin.
-group of muscle fibers that are all part of the same motor unit.
-collection of myofibrils in a muscle fiber.
-group of muscle fibers and motor neurons.
-group of muscle fibers that are encased in the perimysium.
group of muscle fibers that are encased in the perimysium.
Put the following structures in order from superficial to deep.
1. muscle fiber
2. perimysium
3. myofibril
4. fascicle
5. endomysium
6. epimysium
6, 2, 4, 5, 1, 3
Interactions between actin and myosin filaments of the sarcomere are responsible for
-the conduction of neural stimulation to the muscle fiber.
-muscle relaxation.
-the striped appearance of skeletal muscle.
-muscle fatigue.
-muscle contraction.
muscle contraction.
The repeating unit of a skeletal muscle fiber is the
-sacroplasmic reticulum
-myofilament
-sacrolemma
-sacromere
-myofibril
sacromere
At rest, the tropomyosin molecule is held in place by
-myosin molecules
-calcium ions
-actin molecules
-ATP molecules
-troponin molecules
troponin molecules
Action potentials at the sarcolemma are conducted into the inside of a skeletal muscle fiber by
-triads.
-motor end plates.
-transverse tubules.
-sarcoplasmic reticulum.
-neuromuscular junctions.
transverse tubules.
The most important factor in decreasing the intracellular concentration of calcium ion after contraction is
-diffusion of calcium out of the cell.
-active transport of calcium across the sarcolemma.
-active transport of calcium into the sarcoplasmic reticulum.
-diffusion of calcium into the sarcoplasmic reticulum.
-active transport of calcium into the synaptic cleft.
Active transport of calcium into the sarcoplasmic reticulum.
The protein that regulates muscle contraction by controlling the availability of active sites on actin is called
-actin
-titin
-myosin
-tropomyosin
-nebulin
Tropomyosin
In the sarcomere which elastic protein attaches the thick filament to the Z line?
-titin
-actin
-G actin
-nebulin
-myosin
Titin
What are the steps to muscle contraction?
- Calcium ions arrive within the zone of overlap.
- Calcium ions bind to troponin. Active sites on actin are exposed.
- The myosin heads bind to actin active sites.
- The myosin head pivots (power stroke). ADP and P are released.
- ATP binds to the myosin head, breaking the link.
- The free myosin head “recocks”. ADP and P are released.
(Yes! The contraction cycle begins with the arrival of calcium ions to the zones of overlap via excitation-contraction coupling. Then, calcium ions bind to the troponin-tropomyosin complex, causing troponin to change position. Troponin’s movement rolls tropomyosin away from actin’s active sites, thus allowing them to form cross-bridges with energized myosin heads. After cross-bridge formation, the energy that was stored in the resting state is released as the myosin head pivots towards the M line (coincident with the release of bound ADP and P). This is known as the power stroke. Finally, to disengage cross-bridges following the power stroke, ATP binds to the myosin head, and the bond between myosin and actin is broken. Myosin is reactivated for further cycling when ATP is converted into ADP and P, and the myosin head returns to its original conformation.)
In response to action potentials arriving along the transverse tubules, the sarcoplasmic reticulum releases
-hydrogen ions
-calcium ions
-acetylcholine
-sodium ions
-potassium ions
calcium ions
When acetylcholine binds to receptors at the motor end plate, the sarcolemma becomes
-less permeable to potassium and sodium ions.
-more permeable to calcium ions.
-less permeable to potassium ions.
-less permeable to sodium ions.
-more permeable to sodium ions.
more permeable to sodium ions
Which of the following statements about excitation-contraction coupling is incorrect?
-Calcium ion is released from the sarcoplasmic reticulum.
-Tropomyosin moves to expose myosin binding sites on actin.
-Troponin binds calcium ion and signals tropomyosin to move.
-Calcium ions travel through the transverse tubule.
-Relaxation requires uptake of calcium ion by the sarcoplasmic reticulum.
Calcium ions travel through the transverse bubble.
A patient takes a medication that blocks ACh receptors of skeletal muscle fibers. What is this drug’s effect on skeletal muscle contraction?
-produces a strong, continuous state of contraction
-increases tone in the muscle
-increases the muscle’s excitability
-causes a strong contraction similar to a “charlie horse” cramp
-reduces the muscle’s ability for contraction
Reduces the muscle’s ability for contraction
Cross bridge detachment is caused by ________ binding to the myosin head.
-calcium
-ATP
-magnesium
-acetlycholinesterase
-acetylcholine
ATP
Put the following events of excitation-contraction coupling in the order in which they occur.
1. Excitation
2. Sarcomere shortening
3. Generation of muscle tension
4. Neural control
5. Contraction cycle begins
6. Release of calcium ions
4, 1, 6, 5, 2, 3
Put the following events of the contraction cycle in the order in which they occur.
1. Cross-bridge detachment
2. Cross-bridge formation
3. Active site exposure
4. Myosin reactivation
5. Calcium ions bind troponin
6. Myosin head pivoting
5, 3, 2, 6, 1, 4
The following is a list of the events that occur during a muscle contraction. What is the correct sequence of these events?
1. Myosin cross-bridges bind to the actin.
2. The free myosin head splits ATP.
3. Calcium ion is released from the sarcoplasmic reticulum.
4. The myosin head pivots toward the center of the sarcomere.
5. Calcium ion binds to troponin.
6. The myosin head binds an ATP molecule and detaches from the actin.
3, 5, 1, 4, 6, 2
Put the following events of the neuromuscular junction in the order in which they occur.
1. Action potential is propagated in the sarcolemma.
2. Acetylcholine binds to ligand gated sodium channels.
3. Action potential arrives at the neuromuscular junction.
4. Vesicles full of acetylcholine are stored at the axon terminal.
5. Acetylcholine is released into the synaptic cleft.
4, 3, 5, 2, 1
The electric potential difference across the cell membrane is known as
-the membrane potential.
-the cellular difference.
-the cellular potential.
-the plasmalemma potential.
-the membrane difference.
the membrane potential
The concentrations of sodium and potassium are fairly constant. However, there is a transmembrane potential charge difference that exists across the membrane. How is this possible?
-The cell membrane is impermeable to sodium and potassium.
-Leak channels allow sodium and potassium to move across the membrane, causing the difference in electric charge.
-The concentrations of sodium and potassium are not equal inside and outside the cell.
-The cell is more negative outside than inside.
The concentrations of sodium and potassium are not equal inside and outside the cell.
The resting membrane potential is dependent upon two important factors:
1.
2.
1) differences in sodium and potassium concentrations across the membrane (electrochemical gradients)
2) differences in sodium and potassium membrane permeability.
The separation of charges creates a _____, which can be measured using a voltmeter.
voltage (electrical potential difference)
The resting membrane potential of a neuron averages _____.
-70 mV
All neural activities begin with a _____.
change in the resting membrane potential of a neuron.
The concentration of _____ is higher inside than outside the cell.
K+
The membrane is more permeable to ____.
K+
The concentration of _____ is higher outside than inside the cell.
Na+
The resting membrane potential is maintained by Na+-K+ pumps that actively transport ____ into and ____ out of the cell.
K+; Na+
Ions are unequally distributed across the plasma membrane of all cells. This ion distribution creates an electrical potential difference across the membrane. What is the name given to this potential difference?
-Positive membrane potential
-Action potential
-Resting membrane potential (RMP)
-Threshold potential
Resting membrane potential (RMP)
(Yes! The resting membrane potential is the baseline potential that can be recorded across the plasma membrane of an excitable cell prior to excitation.)
Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel?
-Ligand-gated channels
-Sodium-potassium ATPases
-Voltage-gated channels
-Leak channels
Leak channels.
(Yes. Leak channels for Na+ and K+ are ubiquitous, and they allow for the diffusion of these ions across plasma membranes.)
On average, the resting membrane potential is -70 mV. What does the sign and magnitude of this value tell you?
-The inside surface of the plasma membrane is much more negatively charged than the outside surface.
-The outside surface of the plasma membrane is much more negatively charged than the inside surface.
-The inside surface of the plasma membrane is much more positively charged than the outside surface.
-There is no electrical potential difference between the inside and the outside surfaces of the plasma membrane.
The inside surface of the plasma membrane is much more negatively charged than the outside surface.
(Yes! The inside surface of the plasma membrane accumulates more negative charge because of the presence of Na+ and K+ gradients and the selective permeability of the membrane to Na+ and K+.)
The plasma membrane is much more permeable to K+ than to Na+. Why?
-There are many more K+ leak channels than Na+ leak channels in the plasma membrane.
-There are many more voltage-gated K+ channels than voltage-gated Na+ channels.
-Ligand-gated cation channels favor a greater influx of Na+ than K+.
-The Na+-K+ pumps transport more K+ into cells than Na+ out of cells.
There are many more K+ leak channels than Na+ leak channels in the plasma membrane.
(Yes! More leak channels translates into more leakiness. Thus the permeability to K+ is greater than the permeability to Na+, and so K+ contributes the most to determining the resting membrane potential.)
The resting membrane potential depends on two factors that influence the magnitude and direction of Na+ and K+ diffusion across the plasma membrane. Identify these two factors.
-The presence of concentration gradients and voltage-gated channels
-The presence of a resting membrane potential and leak channels
-The presence of concentration gradients and Na+-K+ pumps
-The presence of concentration gradients and leak channels
The presence of concentration gradients and leak channels
(Yes! The large number of K+ leak channels ensures that the membrane is highly permeable to K+. The concentration gradient for K+ means that K+ diffuses out of the cell, leaving the inside of the cell negatively charged. In contrast, the relatively few Na+ leak channels means that the membrane is almost impermeable to Na+. The concentration gradient for Na+ means that Na+ will diffuse into the cell through the few leak channels that are open for it.)
What prevents the Na+ and K+ gradients from dissipating?
-Na+-K+ ATPase
-H+-K+ ATPase
-Na+ and K+ leaks
-Na+ cotransporter
Na+-K+ ATPase
(Yes! Also known as the Na+-K+ pump, or simply the pump, this transporter moves three Na+ out of the cell and two K+ into the cell for every ATP it hydrolyzes. This pumping action prevents the Na+ and K+ gradients from running down as these ions passively move through leak channels.)
