Muscle and Neural Cells

Question 1

Compare and contrast the speed, strength, and contractions of smooth, skeletal, and cardiac muscle.

Answer 1

Smooth: slow, weak, involuntary contractions

Skeletal: fast, strong, voluntary contractions

Cardiac: fast, strong, involuntary contractions

Question 2

Describe structure of smooth muscle

Answer 2

Cells are tapered, with a single nucleus in the middle of the cell.
Very little CT and blood vessels.
No striations.
Found in walls of hollow organs, holds passages (bronchioles) open, causes peristalsis in the intestine.
In the walls of blood vessels, regulates BP and flow.
Metabolic needs are low.

Question 3

Describe the structure of skeletal muscle

Answer 3

Long cells (fibers), multinucleate due to the merging of precursor cells, nucleus is pushed to the periphery of the cell.
Lots of CT and blood vessels in order to support the strong and sustained use of skeletal muscle.
Muscle fibers (cells) make up muscle fascicle. Muscle fascicles make up skeletal muscle.
Striations are visible under the microscope due to the repeating units of actin and myosin (sarcomeres).

Question 4

Describe the structure of cardiac muscle

Answer 4

Cells contain either 1-2 nuclei near the center of the cell. Cells are branching and have intercalated disks.
Lots of blood vessels and CT to support high metabolic activity.
Fibers are long and striated, organized into fascicles.

Question 5

Intercalated discs perform what three major functions?

Answer 5

• anchor sarcomeres
• provide inercellular adhesion
• allow rapid communication of electrical and chemical signals between muscle fibers, allows for coordinated contraction

Question 6

Fascia (zonula) adherens does what within intercalated discs of cardiac muscle?

Answer 6

anchors the sarcomeres and functions in cell adherence

Question 7

Macula adherens (desmosomes) within intercalated discs of cardiac muscle do what?

Answer 7

connect the myofibers to each other and contribute to adherence

Question 8

Gap junctions within intercalated discs of cardiac muscle do what?

Answer 8

allow for rapid communication so that the muscle fibers can contract in unison

Question 9

What are the two cell types in the peripheral nervous system?

Answer 9

Neurons and Schwann cells

Question 10

Describe Schwann cells

Answer 10

Contain a sheet-like extension called myelin that is wrapped around axons. The gaps in myelin are called Nodes of Ranvier and help with conduction speed along the axon.

Question 11

Describe neurons

Answer 11

Most neuron bodies are in or near the CNS, but parasympathetic nerves have ganglia near the hollow organ they control (in walls of). The axons of neurons stretch from the ganglia to whatever area of the body they control. These long projections can come together to form a nerve or a fascicle; fascicles can group together to form a larger nerve

the neurons of ganglion innervate the surrounding smooth muscle