Question

multiple choice. choose the one alternative that best completes the statement or answers the question.

1. one sarcomere

a) extends from z disc to z disc.
b) contains only actin fibers.
c) surrounds each muscle in the body.
d) is composed of many myofibrils.
e) is composed of many muscle fibers.

1. where does saltatory conduction occur?

a) from node to node in myelinated axons b) in the dendrites of sensory neurons
c) from node to node in unmyelinated axons d) down the entire length of an unmyelinated neuron

1. a soft callus forms during

a) the remodeling of bone b) intramembranous ossification
c) the healing of a fracture d) endochondral ossification

1. the expanded head at each end of a long bone is called the

a) diaphysis
b) endosteum
c) articular cartilage
d) periosteum
e) epiphysis

1. which of the following is predominately made up of myosin?

a) the thick filament
b) the elastic filament
c) the thin filament
d) f actin
e) g actin

1. what binds to troponin, and what happens when it binds?

a) t tubules; the sarcomere shortens b) ca²+; tropomyosin shifts position
c) atp; tropomyosin returns to normal position d) acetylcholine; the sarcomere shortens

1. when a nerve impulse reaches the transmissive segment of a neuron,

a) calcium diffuses into the neuron and neurotransmitter is released by exocytosis.
b) calcium and neurotransmitter diffuse into the synaptic knob.
c) calcium is pumped into the neuron and neurotransmitter diffuses out through channels.
d) calcium is released from the neuron along with neurotransmitter from synaptic vesicles.
e) calcium is immediately pumped out of the neuron and vesicles of neurotransmitter undergo phagocytosis.

1. a neuron can receive thousands of epsps from different neurons synapsing at different locations, and responds by triggering or not triggering an action potential. this addition and response to the net effect of postsynaptic potentials is called

a) temporal summation
b) spatial summation
c) neuronal coding
d) neural summation
e) recruitment

1. what is a canaliculus?

a) the large cavity inside a long bone b) a fibrous connective covering of bone
c) a small channel in the matrix of bone d) a type of bone forming cell

Explanation:

1. A sarcomere is the basic unit of striated muscle tissue and extends from Z disc to Z disc.
2. Saltatory conduction occurs from node to node in myelinated axons, which speeds up nerve impulse transmission.
3. A soft callus forms during the healing of a fracture as part of the bone repair process.
4. The expanded head at each end of a long bone is called the epiphysis.
5. The thick filament in muscle fibers is predominantly made up of myosin.
6. \(Ca^{2+}\) binds to troponin, causing tropomyosin to shift position, which is a key step in muscle contraction.
7. When a nerve impulse reaches the transmissive segment of a neuron, calcium diffuses into the neuron and neurotransmitter is released by exocytosis.
8. Spatial summation is when a neuron receives thousands of EPSPs from different neurons synapsing at different locations and responds by triggering or not triggering an action potential based on the net effect of postsynaptic potentials.
9. A canaliculus is a small channel in the matrix of bone.

Answer:

1. A. extends from Z disc to Z disc
2. A. From node to node in myelinated axons
3. C. the healing of a fracture
4. E. epiphysis
5. A. The thick filament
6. B. \(Ca^{2+}\); tropomyosin shifts position
7. A. calcium diffuses into the neuron and neurotransmitter is released by exocytosis
8. B. spatial summation
9. C. a small channel in the matrix of bone