Quiz: Anatomy_H4

Question 1

1. From the options listed below, choose the CORRECT statement(s) regarding the neuromuscular junction and excitation-contraction coupling in skeletal muscle.

Choices:

• In order for cross bridge binding to take place, the active sites on actin filaments must be uncovered
• The binding of acetylcholine to receptors on the surface of a muscle fibre initiates an electrical signal in the sarcolemma
• Acetylcholine is the neurotransmitter at skeletal muscle neuromuscular junctions
• At a neuromuscular junction, the synaptic terminal of a neuron communicates with the motor end plate of a skeletal muscle fibre
• An electrical signal along the transverse tubules causes the sarcoplasmic reticulum to actively take up Ca2+
• Acetylcholinesterase is an enzyme that is responsible for the production of acetylcholine in the synaptic terminal

Answers:

• In order for cross bridge binding to take place, the active sites on actin filaments must be uncovered
• The binding of acetylcholine to receptors on the surface of a muscle fibre initiates an electrical signal in the sarcolemma
• Acetylcholine is the neurotransmitter at skeletal muscle neuromuscular junctions
• At a neuromuscular junction, the synaptic terminal of a neuron communicates with the motor end plate of a skeletal muscle fibre

Comments:

• Correct
• That’s right! NMJ refers to the point of communication between a neuron and a skeletal muscle fibres. Signal propagation requires ACh to bind to AChRs at the motor endplate. Ca2+ binding to troponin uncovers the active site on actin filaments for cross bridge binding.
• Continue

Question 2

2. From the options listed below, choose the CORRECT statement(s) regarding motor units in skeletal muscle.

Choices:

• All muscle fibres in a given motor unit contract at the same time
• Muscles that must be precisely controlled have smaller motor units
• The force generated by a muscle is proportional to the number of motor units recruited
• Larger motor units contain more motor neurons
• Multiple motor neurons synapse onto each muscle fibre

Answers:

• All muscle fibres in a given motor unit contract at the same time
• Muscles that must be precisely controlled have smaller motor units
• The force generated by a muscle is proportional to the number of motor units recruited

Comments:

• Correct
• That’s right! A motor unit is a single motor neuron and all the muscle fibres it innervates. It contracts as a whole, and the force developed is proportional to the number of motor units activated. Small motor units, allow more precise control of a muscle.
• Continue

Question 3

3. Which cell junctions are present at intercalated discs?

Choices:

• Desmosomes
• Fascia adherens
• Gap junctions
• Hemidesmosomes
• Tight junctions

Answers:

• Desmosomes
• Fascia adherens
• Gap junctions

Comments:

• Correct
• That’s right! Gap junctions, fascia adherens and desmosomes are ALL present at the intercalated discs of cardiac muscle.
• Continue

Question 4

4. Identify the class of tissue. Be specific.

Choices:

• skeletal muscle tissue
• skeletal muscle
• muscle tissue, skeletal

Answers:

• skeletal muscle tissue
• skeletal muscle
• muscle tissue, skeletal

Comments:

• Correct
• That’s right! Skeletal muscle tissue can be identified by i) the striations, ii) the straight, unbranched cells and iii) numerous nuclei in each cell.
• Continue

Question 5

5. Identify the class of tissue. Be specific.

Choices:

• smooth muscle tissue
• smooth muscle
• muscle tissue, smooth

Answers:

• smooth muscle tissue
• smooth muscle
• muscle tissue, smooth

Comments:

• Correct
• That’s right! Smooth muscle tissue can be identified by i) the absence of striations, ii) the one, elongated nucleus in each cell and iii) the tapering, “spindle-shape” of the cells.
• Continue

Question 6

6. Identify the class of tissue. Be specific.

Choices:

• skeletal muscle tissue
• skeletal muscle
• muscle tissue, skeletal

Answers:

• skeletal muscle tissue
• skeletal muscle
• muscle tissue, skeletal

Comments:

• Correct
• That’s right! Skeletal muscle tissue can be identified in cross section by i) the large size of the cells relative to the nuclei, ii) the peripheral placement of the nuclei, and iii) the connective tissue elements surrounding the cells.
• Continue

Question 7

7. Identify A. Be specific.

Choices:

• endomysium

Answers:

• endomysium

Comments:

• Correct
• That’s right! Endomysium is the delicate connective tissue layer that surrounds and connects individual skeletal muscle fibres.
• Continue

Question 8

8. Identify the class of tissue. Be specific.

Choices:

• cardiac muscle
• cardiac muscle tissue
• muscle, cardiac

Answers:

• cardiac muscle
• cardiac muscle tissue
• muscle, cardiac

Comments:

• Correct
• That’s right! Cardiac muscle tissue in longitudinal section can be identified by i) the branching, anastomosing cells, ii) the striations, iii) the single nucleus per cell, and iv) the intercalated discs.
• Continue

Question 9

9. Identify the class of tissue. Be specific.

Choices:

• cardiac muscle
• cardiac muscle tissue
• muscle, cardiac

Answers:

• cardiac muscle
• cardiac muscle tissue
• muscle, cardiac

Comments:

• Correct
• That’s right! Cardiac muscle tissue in cross section can be identified by i) the position of the nuclei in the centre of the cells and ii) the irregular shape of the cells.
• Continue

Question 10

10. Identify A. Be specific.

Choices:

• perimysium

Answers:

• perimysium

Comments:

• Correct
• That’s right! A muscle fascicle, a group of skeletal muscle fibres, is surrounded by the perimysium.
• Continue

Question 11

11. Identify the class of tissue. Be specific.

Choices:

• smooth muscle
• smooth muscle tissue
• muscle tissue, smooth

Answers:

• smooth muscle
• smooth muscle tissue
• muscle tissue, smooth

Comments:

• Correct
• That’s right! This is a cross section of smooth muscle. The nuclei are centrally-located, and large relative to the cells. Because the cells taper, many are not cut through the nucleus and so appear to lack a nucleus.
• Continue

Question 12

12. Identify the structures at the tips of the arrows.

Choices:

• intercalated discs

Answers:

• intercalated discs

Comments:

• Correct
• That’s right! These are intercalated discs, which connect the cytoskeletons of adjacent cardiocytes via desmosomes and fascia adherens. Gap junctions join the cells electrically.
• Continue

Question 13

13. Identify cardiac muscle tissue in longitudinal section and click on the letter of the corresponding image below.

Choices:

• Rectangular Hotspot 1
• Incorrect

Answers:

• Rectangular Hotspot 1

Comments:

• Correct
• That's right! Diagram C represents cardiac muscle tissue in longitudinal section. Notice the striations, branching of cells and the intercalated discs.
• Continue

Question 14

14. Identify smooth muscle tissue in longitudinal section and click on the letter of the corresponding image below.

Choices:

• Rectangular Hotspot 1
• Incorrect

Answers:

• Rectangular Hotspot 1

Comments:

• Correct
• That's right! Diagram B represents smooth muscle tissue in longitudinal section. Notice the large and elongated nuclei of tapered cells.
• Continue

Question 15

15. Identify skeletal muscle tissue in longitudinal section and click on the letter of the corresponding image below.

Choices:

• Rectangular Hotspot 1
• Incorrect

Answers:

• Rectangular Hotspot 1

Comments:

• Correct
• That's right! Diagram A represent skeletal muscle tissue in longitudinal section. Skeletal muscle cells are striated, straight and multi-nucleated.
• Continue

Question 16

16. Identify smooth muscle tissue in cross-section and click on the letter of the corresponding image below.

Choices:

• Rectangular Hotspot 1
• Incorrect

Answers:

• Rectangular Hotspot 1

Comments:

• Correct
• That's right! Diagram B represents smooth muscle tissue in cross section. Notice how the nuclei are larger relative to the cells and that not all cells appear to contain nuclei due to tapering nature.
• Continue

Question 17

17. Identify skeletal muscle tissue in cross section and click on the letter of the corresponding image below.

Choices:

• Rectangular Hotspot 1
• Incorrect

Answers:

• Rectangular Hotspot 1

Comments:

• Correct
• That's right! Diagram C represents skeletal muscle tissue in cross section. Notice how the nuclei are located at the periphery of the muscle fibre.
• Continue

Question 18

18. Identify cardiac muscle tissue in cross section and click on the letter of the corresponding image below.

Choices:

• Rectangular Hotspot 1
• Incorrect

Answers:

• Rectangular Hotspot 1

Comments:

• Correct
• That's right! Diagram A represents cardiac muscle tissue in cross section. The nuclei are centrally located with cells in irregular shape.
• Continue