Lab 7 (Nerve + Muscle Tissues, NJM, Spinal Cord, Spinal Nerves, Somatic Reflexes) Review

Neuron

specialized cells that transmit nerve impulses.

Soma (Cell Body)

neuron cell body, containing the nucleus and perikaryon (cytoplasm)

Dendrites

receive impulses toward the soma.

Axon

carries impulses away from the soma received from other neurons/cells.

Oligodendrocytes

myelinate central nervous system (CNS) axons.

Schwann Cells

myelinate peripheral nervous system (PNS) axons.

Afferent (Sensory) Neurons

carry impulses towards the CNS.

Efferent (Motor) Neurons

carry impulses away from CNS.

Interneurons

entirely within CNS (brain + spinal cord); receives, processes, and decides how the body responds to stimuli.

Skeletal Muscle

fibers attached to skeleton; striated, voluntary.

Cardiac Muscle

only cover walls of the heart; branched, intercalated discs.

Smooth Muscle

covering wall of internal organs; no striations, involuntary.

Neuromuscular Junction

how a nerve signal becomes a muscle contraction.

Steps of Muscle Contraction

1. The nerve signal reaches the axon terminal.

2. Calcium enters the terminal. (MUST KNOW)

3. Causes vesicles to release ACh into the synaptic cleft. (MUST KNOW)

4. ACh binds to receptors on the muscle. (MUST KNOW)

5. Immediately after, muscle creates its own action potential. (MUST KNOW)

6. Signal travels down sarcolemma + T-tubules.

7. Calcium is released from the sarcoplasmic reticulum (SR).

8. Calcium binds to troponin directly, causing the muscle to contract. (MUST KNOW)

Patellar Reflex

L2- L4, function of leg extension.

Biceps Reflex

C5-C6, forearm flexion.

Triceps Reflex

C7-C8, forearm extension.