MASTERING A&P Chapters 6,8,9,11

Which of the following pairs is MISMATCHED? a) tarsals: short bones b) femur: long bone c) sternum: long bone d) skull bones: flat bones

Which of the following statements is true? a) Osteoclasts are important in removing calcium from the blood stream. b) Bone would be more brittle with more collagen in the matrix. c) The red marrow in the medullary cavity produces our red blood cells. d) Spongy bone is well adapted to accept stress in many directions, which makes it good for shock absorption.

There are several components to a functional osteon. Changes to which of the following components would make the bones less strong overall and cause the bones to bend under a person's body weight? a) osteoid b) articular cartilage c) hydroxyapatite d) periosteum

An imbalance that activates these bone cells would lead to a loss of bone density. a) osteoclasts b) osteocytes c) chondroblasts d) osteoblasts

What would be the physical sign that a bone CANNOT continue longitudinal growth? a) the presence of osteoblasts b) the presence of osteons c) an epiphyseal line d) the presence of hyaline cartilage on the ends of the bone

What controls bone remodeling? a) mechanical stress and hormones b) mechanical stress and diet c) hormones and diet d) the nervous system and hormones

What is the first stage in the healing of a bone fracture? a) formation of a bony callus b) bone remodeling c) formation of a fibrocartilaginous callus d) formation of a hematoma

What is a common characteristic of a syndesmosis and a symphysis? a) Both may be slightly movable. b) Both are cartilaginous joints. c) Both are classified as synarthroses. d) Both are found exclusively in the appendicular skeleton.

What structural arrangement usually permits the greatest freedom of movement in a joint? a) bones joined by a fluid-filled articular capsule b) bones joined by fibrocartilage pads c) bones joined by a fibrous ligament d) bones united by a hyaline cartilage bar or plate

Most joints of the body and nearly all the joints in the limbs are __________. a) amphiarthrotic synovial joints b) diarthrotic syndesmoses c) amphiarthrotic synchondroses d) diarthrotic synovial joints

Which types of joints may form synostoses during normal growth and development? a) synchondroses and symphyses b) gomphoses and syndesmoses c) syndesmoses and sutures d) synchondroses and sutures

Which type of movement is unique to the forearm? a) pronation b) opposition c) adduction d) extension

What is the role of calcium in the cross bridge cycle? a) Calcium binds to troponin, exposing the active site on troponin. b) Calcium binds to myosin, causing the myosin head to release from the actin myofilament. c) Calcium binds to active sites on actin, forming the cross bridge. d) Calcium binds to troponin, altering its shape.

What role does tropomyosin play in the cross bridge cycle? a) Tropomyosin binds to calcium, causing muscle relaxation. b) Tropomyosin pushes the myosin head away, causing cross bridge detachment. c) The displacement of tropomyosin exposes the active sites of actin, allowing cross bridges to form. d) Tropomyosin moves the actin filament relative to the myosin filament.

How does troponin facilitate cross bridge formation? a) Troponin hydrolyzes ATP, which provides the energy necessary for cross bridges to form. b) Troponin moves away from the active sites on actin, permitting cross bridge formation. c) Troponin gathers excess calcium that might otherwise block actin's progress. d) Troponin controls the position of tropomyosin on the thin filament, enabling myosin heads to bind to the active sites on actin.

What, specifically, is a cross bridge? a) ATP binding to the myosin head b) tropomyosin covering the active sites on actin c) calcium binding to troponin d) myosin binding to actin

Which event causes cross bridge detachment? a) ATP binding to the myosin head b) release of calcium from troponin c) nervous input ends d) release of ADP and inorganic phosphate from the myosin head

Where in the cross bridge cycle does ATP hydrolysis occur? a) during the cocking of the myosin head b) during the power stroke c) during the movement of tropomyosin to expose the active sites on actin d) during the removal of calcium from troponin

How/when does the myosin head cock back to store energy for the next cycle? a) The power stroke cocks the myosin head. b) The sliding of the actin myofilament during the power stroke re-cocks myosin heads that have previously delivered their power stroke. c) After the myosin head detaches, energy from ATP hydrolysis is used to re-cock the myosin head. d) when ADP is released from the myosin head

BMD (2,3-butanedione 2-monoximime) inhibits myosin, such that ATP can bind to myosin but myosin is unable to hydrolyze the bound ATP. What effect would BMD have on the cross bridge cycle? a) Myosin heads would remain attached to actin, unable to perform the power stroke. b) Myosin heads would remain attached to actin, unable to detach. c) Myosin heads would remain detached, unable to cock. d) Tropomyosin would not move, and the active sites on actin would not be exposed.

During contraction, what prevents actin myofilaments from sliding backward when a myosin head releases? a) Calcium blocks the active sites on actin. b) The actin myofilament can only move in one direction relative to the myosin filament. c) The cross bridge remains in place, preventing the actin myofilament from sliding. d) There are always some myosin heads attached to the actin myofilament when other myosin heads are detaching.

Skeletal muscle cells are grouped into bundles called __________. a) muscle fibers b) fascicles c) myofibrils d) myofilaments

Synaptic vesicles at the neuromuscular junction contain __________. a) synaptic potentials b) ACh receptors c) acetylcholine d) calcium

ACh receptors are found mainly in the __________. a) sarcolemma b) axon terminal c) terminal cisternae d) synaptic vesicles

What most directly causes synaptic vesicles to release acetylcholine into the synaptic cleft? a) depolarization of the sarcolemma b) an action potential arriving at the axon terminal c) calcium entering the axon terminal d) sodium entering the muscle fiber

Acetylcholine receptors are best characterized as what type of channel? a) voltage-gated Ca2+ channels b) chemically gated Ca2+ channels c) voltage-gated Na+-K+ channels d) chemically gated Na+-K+ channels

When the chemically gated ion channels open, which ion is mainly responsible for depolarizing the sarcolemma? a) calcium b) ACh c) potassium d) sodium

What is the primary mechanism by which ACh is cleared from the synaptic cleft? a) endocytosis by synaptic vesicles b) diffusion away from the synaptic cleft c) reuptake into the synaptic terminal d) broken down by acetylcholinesterase

What would happen if acetylcholine was not removed from the synaptic cleft? a) Multiple action potentials would occur in the muscle fiber. b) Voltage-gated Ca2+ channels would remain open. c) Multiple action potentials would occur in the motor neuron. d) The acetylcholine receptors would not open.

Which of the following is true concerning the anatomy of a skeletal muscle fiber? a) T tubules are extensions of the sarcoplasmic reticulum. b) A triad consists of a T tubule and the nearby sarcolemma. c) The sarcolemma is the muscle fiber's cytoplasm. d) Myofibrils contain thick and thin filaments.

The calcium that initiates skeletal muscle contraction is released from what structure(s)? a) sarcomeres b) sarcolemma c) T tubules d) terminal cisternae

Which of the following are composed of myosin? a) thin filaments b) intermediate filaments c) tropomyosin d) thick filaments

In muscle fibers, which regulatory protein blocks the attachment of myosin heads to actin? a) tropomyosin b) calcium c) acetylcholinesterase d) thick filaments

What event most directly triggers the release of calcium from the terminal cisternae? a) movement of tropomyosin away from the active sites on actin b) action potential propagating toward the axon terminal c) cross bridge formation between the thick and thin filaments d) action potential propagating down the T tubule

How do calcium ions initiate contraction in skeletal muscle fibers? a) Calcium ions provide the energy necessary for the myosin head power stroke. b) Calcium ions bind to tropomyosin, exposing the active sites on actin. c) Calcium ion movement depolarizes the sarcolemma at the synaptic cleft. d) Calcium ions bind to troponin, changing troponin's shape.

Which of the following best describes the events of "excitation" in "excitation-contraction coupling"? a) propagation of the action potential along the sarcolemma b) cross bridge formation c) release of calcium from the terminal cisternae d) movement of tropomyosin away from the active sites on actin

Which of the following best describes the events of "contraction" in "excitation-contraction coupling"? a) sliding of myofilaments b) propagation of the action potential along the sarcolemma of the muscle fiber c) release of calcium from the terminal cisternae d) cross bridge formation

Which type of muscle requires voluntary nervous stimulation for activation? a) visceral b) cardiac c) skeletal d) smooth

Muscle tissue can be stimulated by the nervous system. This is because of the membrane potential in the muscle cell. Cells with a membrane potential have what property? a) contractility b) excitability c) extensibility d) elasticity

Which term best identifies a muscle cell? a) muscle fascicle b) sarcomere c) muscle fiber d) myofibril

The __________ shorten(s) during muscle contraction a) actin b) thick filament c) sarcomere d) Z lines

The sliding filament model of contraction states that __________. a) during contraction, the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments no longer overlap b) during contraction, the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments overlap to a greater degree c) during contraction, the thin myofilaments slide past the thick myofilaments so that calcium ions can be released from the sarcoplasmic reticulum d) during contraction, the thin myofilaments slide past T tubules so that the Z discs are overlapping

What is the term for a group of muscle fibers innervated by a single neuron? a) fascicle b) motor unit c) sarcomere d) neuromuscular junction

Slow oxidative muscle fibers are best suited for __________. a) hitting a baseball b) lifting heavy weights at the gym c) running a 100-yard dash d) running a marathon

Which of the following factors influence the velocity and duration of muscle contraction? a) length of muscle fibers activated b) load placed on the muscle c) muscle-fiber size d) frequency of stimulation

Which of the following is true? a) Skeletal muscle fibers tend to be shorter than smooth muscle fibers. b) Smooth muscle lacks the thin and thick filaments characteristic of skeletal muscle. c) Skeletal muscle fibers contain sarcomeres; smooth muscle fibers do not. d) Skeletal muscle lacks the coarse connective tissue sheaths that are found in smooth muscle.

What feature of smooth muscle allows it to stretch without immediately resulting in a strong contraction? a) stress-relaxation response b) smooth muscle tone c) low energy requirements d) slow, prolonged contractile activity

Which of the following peripheral nervous system (PNS) neuroglia form the myelin sheaths around larger nerve fibers in the PNS? a) Schwann cells b) astrocytes c) satellite cells d) oligodendrocytes

Which is the main receptive portion of the neuron? a) the dendrite b) the cell body or soma c) the synapse d) the axon

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? a) Threshold potential b) Resting membrane potential (RMP) c) Positive membrane potential d) Action potential

Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel? a) Voltage-gated channels b) Ligand-gated channels c) Leak channels d) Sodium-potassium ATPases

On average, the resting membrane potential is -70 mV. What does the sign and magnitude of this value tell you? a) The outside surface of the plasma membrane is much more negatively charged than the inside surface. b) The inside surface of the plasma membrane is much more negatively charged than the outside surface. c) The inside surface of the plasma membrane is much more positively charged than the inside surface. d) There is no electrical potential difference between the inside and the outside surfaces of the plasma membrane.

The plasma membrane is much more permeable to K+ than to Na+. Why? a) There are many more K+ leak channels than Na+ leak channels in the plasma membrane. b) There are many more voltage-gated K+ channels than voltage-gated Na+ channels. c) The Na+-K+ pumps transport more K+ into cells than Na+ out of cells. d) Ligand-gated cation channels favor a greater influx of Na+ than K+.

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. a) The presence of concentration gradients and leak channels b) The presence of a resting membrane potential and leak channels c) The presence of concentration gradients and voltage-gated channels d) The presence of concentration gradients and Na+-K+ pumps

What prevents the Na+ and K+ gradients from dissipating? a) Na+ and K+ leaks b) Na+-K+ ATPase c) Na+ cotransporter d) H+-K+ ATPase

The small space between the sending neuron and the receiving neuron is the a) synaptic cleft. b) synaptic terminal. c) vesicle. d) neurotransmitter. e) calcium channel.

A molecule that carries information across a synaptic cleft is a a) synaptic cleft. b) sending neuron. c) receiving neuron. d) synapse. e) neurotransmitter.

When calcium ions enter the synaptic terminal, a) neurotransmitter molecules are quickly removed from the synaptic cleft. b) they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron. c) the inside of the receiving neuron becomes more negative. d) they cause an action potential in the sending neuron. e) the inside of the receiving neuron becomes more positive.

When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron, a) vesicles in the synaptic terminal fuse to the plasma membrane of the sending neuron. b) the receiving neuron becomes more negative inside. c) ion channels in the plasma membrane of the receiving neuron open. d) the receiving neuron becomes more positive inside. e) ion channels in the plasma membrane of the sending neuron open.

If a signal from a sending neuron makes the receiving neuron more negative inside, a) the sending neuron becomes more positive inside. b) the receiving neuron immediately generates an action potential. c) the sending neuron becomes more negative inside. d) the receiving neuron is more likely to generate an action potential. e) the receiving neuron is less likely to generate an action potential.

What type of conduction takes place in unmyelinated axons? a) Electrical conduction b) Saltatory conduction c) Synaptic transmission d) Continuous conduction

An action potential is self-regenerating because __________. a) repolarizing currents established by the efflux of Na+‎ flow down the axon and trigger an action potential at the next segment b) depolarizing currents established by the influx of K+‎ flow down the axon and trigger an action potential at the next segment c) repolarizing currents established by the efflux of K+‎ flow down the axon and trigger an action potential at the next segment d) depolarizing currents established by the influx of Na+‎ flow down the axon and trigger an action potential at the next segment

Why does regeneration of the action potential occur in one direction, rather than in two directions? a) The activation gates of voltage-gated K+‎ channels open in the node, or segment, that has just depolarized. b) The inactivation gates of voltage-gated Na+‎ channels close in the node, or segment, that has just fired an action potential. c) The inactivation gates of voltage-gated K+‎ channels close in the node, or segment, that has just fired an action potential. d) The activation gates of voltage-gated Na+‎ channels close in the node, or segment, that has just depolarized.

What is the function of the myelin sheath? a) The myelin sheath increases the insulation along the entire length of the axon. b) The myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals. c) The myelin sheath decreases the resistance of the axonal membrane to the flow of charge. d) The myelin sheath decreases the speed of action potential conduction from the initial segment to the axon terminals.

What changes occur to voltage-gated Na+ and K+ channels at the peak of depolarization? a) Activation gates of voltage-gated Na+‎ channels close, while activation gates of voltage-gated K+‎ channels open. b) Inactivation gates of voltage-gated Na+‎ channels close, while activation gates of voltage-gated K+‎ channels open. c) Activation gates of voltage-gated Na+‎ channels close, while inactivation gates of voltage-gated K+‎ channels open. d) Inactivation gates of voltage-gated Na+‎ channels close, while inactivation gates of voltage-gated K+‎ channels open.

In which type of axon will velocity of action potential conduction be the fastest? a) Unmyelinated axons of the shortest length b) Myelinated axons with the largest diameter c) Unmyelinated axons with the largest diameter d) Myelinated axons with the smallest diameters

If a neuron had a mutation that prevented the production of voltage-gated Na+ channels, what function would the neuron NOT be able to accomplish? a) resting membrane potentials b) depolarization leading to action potentials c) graded hyperpolarization d) graded depolarization

What type of stimulus is required for an action potential to be generated? a) multiple stimuli b) a threshold level depolarization c) hyperpolarization d) a suprathreshold stimulus

Which membrane potential occurs because of the influx of Na+ through chemically gated channels in the receptive region of a neuron? a) inhibitory postsynaptic potential b) inhibitory action potential c) action potential d) excitatory postsynaptic potential

A postsynaptic cell can be a neuron, a muscle cell, or a secretory cell. What is an example of a presynaptic cell? a) a secretory cell b) a muscle cell c) a Schwann cell d) a neuron

Which component has a role in the postsynaptic cell during synaptic activity? a) chemically gated channels b) axon terminal c) calcium channels d) Vesicles filled with neurotransmitter

What is the role of calcium in synaptic activity? a) Calcium diffuses across the synaptic cleft and binds to receptors on the postsynaptic neuron. b) Calcium influx into the axon causes an action potential to propagate into the synaptic terminal. c) Calcium influx into the synaptic terminal causes vesicle fusion. d) Calcium degrades neurotransmitter in the synaptic cleft.

What is the role of neurotransmitter at a chemical synapse? a) Neurotransmitter causes a graded potential in the postsynaptic cell. b) Neurotransmitter binds to receptors on the postsynaptic cell membrane and allows ions to diffuse across the membrane. c) Neurotransmitter causes calcium to flood into the presynaptic cell. d) Neurotransmitter causes vesicles to fuse with the presynaptic membrane.

Neurotransmitter is released from presynaptic neurons through what mechanism? a) pinocytosis b) phagocytosis c) exocytosis d) endocytosis

What type of channel on the postsynaptic membrane binds neurotransmitter? a) a mechanically gated channel b) a leakage channel c) a voltage-gated channel d) a chemically gated channel

In addition to diffusion, what are two other mechanisms that terminate neurotransmitter activity? a) reuptake and degradation b) reuptake and inhibition c) exocytosis and degradation d) excitation and degradation

Events that occur during synaptic activity are listed here, but they are arranged in an incorrect order. Choose the correct order of these events below. (a) Voltage-gated calcium channels open (b) Neurotransmitter binds to receptors (c) Action potential arrives at axon terminal (d) Neurotransmitter is removed from the synaptic cleft (e) Neurotransmitter released into synaptic cleft (f) Graded potential generated in postsynaptic cell a) (c) Action potential arrives at axon terminal (a) Voltage-gated calcium channels open (e) Neurotransmitter released into synaptic cleft (b) Neurotransmitter binds to receptors (f) Graded potential generated in postsynaptic cell (d) Neurotransmitter is removed from the synaptic cleft b) (c) Action potential arrives at axon terminal (a) Voltage-gated calcium channels open (e) Neurotransmitter released into the synaptic cleft (d) Neurotransmitter is removed from the synaptic cleft (b) Neurotransmitter binds to receptors (f) Graded potential generated in postsynaptic cell c) (d) Neurotransmitter is removed from the synaptic cleft (b) Neurotransmitter binds to receptors (f) Graded potential generated in postsynaptic cell (c) Action potential arrives at axon terminal (a) Voltage-gated calcium channels open (e) Neurotransmitter released into the synaptic cleft d) (a) Voltage-gated calcium channels open (e) Neurotransmitter released into the synaptic cleft (c) Action potential arrives at axon terminal (b) Neurotransmitter binds to receptors (f) Graded potential generated in postsynaptic cell (d) Neurotransmitter is removed from the synaptic cleft