Muscle Tissue

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Muscle Tissue

1.How is muscle tissue categorized? Muscle tissue is categorized by its shape, the number of nuclei, and the mechanism of stimulation.

2.a. Click the Smooth Muscle Tissue. Identify each of the following:

Nucleus-----

Smooth Fiber Muscle------------------

b.Describe smooth muscle control (voluntary or involuntary). Involuntary

c.Name some smooth muscle functions (click the “Tissue Locations” button). Smooth muscle is found within the walls of all hollow or tubular organs of the digestive, respiratory, urinary, and reproductive tracts.

3.Click the “Cardiac Muscle Tissue.”
a.Identify each of the following:
• Intercalated Disc ---------------------------------------------------------------------------- • Nucleus ------------------------------------------------------------------------- • Cardiac muscle fiber (cell)------------------------ • Striations-------------------------------------- • Gap junctions-----------------------------------------------------

b.Describe cardiac tissue control (voluntary or involuntary). Involuntary

c.Name cardiac tissue function (click the “Tissue Locations” button). Found in the wall of the heart in a muscular layer called the myocardium.

4.Click the “Skeletal Tissue.”
a.Identify each of the following.

Skeletal muscle fiber--------------

Nucleus-----

Striations-----------------------------------

b.Describe control of skeletal muscle contractions (voluntary or involuntary). Voluntary

c.Describe skeletal muscle functions (click the “Tissue Location” button).

Helps maintain posture, Moves skeletal bones in the face, pharynx, larynx, and diaphragm.

Neuromuscular Junctions

Introduction

1.Voluntary muscles are controlled by the brain. Describe this neural connection. An action potential starts from the brain to signal skeletal muscle contraction. Action potentials continue along a motor neuron to the muscle cell.

Components of the NMJ

2.Identify each of the following:

• Motor neuron. Upper part.
• Synaptic end bulb. Mid section.
• Sarcolemma. Front splice.
• Skeletal Muscle Cell. Outer right part.
• Synaptic Cleft. Inner section.

3.a. Define a neuromuscular junction. The chemical synapse between the motor neuron membrane and the muscle membrane.

b.Define a synaptic cleft. The physical space that separates the two cell membranes.

c.What is the function of acetylcholine? Neurotransmitter chemical that carries the information from the muscle cell to the neuron across the synaptic cleft.

Neurotransmission and the NMJ

4.What affect does depolarization have on the motor end plate once action potentials arrive at the synaptic end bulb? This change in voltage opens voltage-gated calcium channels allowing calcium to flood into the neuron.

5.What is the affect of increased calcium within the neuron? Causes synaptic vesicles to fuse with the neuron membrane, and acetylcholine is then released into the synaptic cleft.

6.What affect does acetylcholine have on the sarcolemma? It triggers the opening of sodium channels resulting in the rapid entry of sodium into the muscle cell.

7.What affect do increased sodium ions have on the muscle cell? It depolarizes the sarcolemma and generates a muscle action potential that travels along the membrane.

Initiation of Contraction

8.Once an action potential goes down a T-tubule, what affect does it have on the terminal cisterns of the sarcoplasmic reticulum? It causes changes in the terminal cisterns of the SR.

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