bio lecture 12 for exam 2 notes (copy)

Striations

Present in skeletal and cardiac muscle cells; absent in smooth muscle cells.

Involuntary control

Control of muscle contractions that occur without conscious thought, as seen in cardiac and smooth muscles.

Voluntary control

Control of muscle contractions that can be consciously controlled, as seen in skeletal muscles.

Multinucleated

Having multiple nuclei, characteristic of skeletal muscle cells.

Uninucleated

Having a single nucleus, characteristic of cardiac and smooth muscle cells.

Neurons

Highly specialized cells responsible for conducting nerve impulses.

Neuroglia

Support and nourish neurons, compensating for neurons' limited organelles.

Axon

A single, long extension from the cell body that conducts nerve impulses away from the neuron.

Myelin sheath

An electrical insulator covering most axons formed by Schwann cells and oligodendrocytes.

Nodes of Ranvier

Brief breaks in the myelin sheath that facilitate saltatory conduction.

Astrocytes

Star-shaped neuroglial cells that support neurons and regulate the chemical environment.

Oligodendrocytes

Neuroglial cells that form myelin sheaths around axons in the central nervous system.

Schwann Cells

Neuroglial cells that form myelin sheaths around axons in the peripheral nervous system.

Microglia

Immune cells of the central nervous system that phagocytize debris and pathogens.

Ependymal Cells

Line ventricles of the brain and spinal cord, producing cerebrospinal fluid.

Epithelial Tissues

Composed of tightly packed cells forming barriers for secretion, absorption, excretion, and filtration.

Neuron to neuroglial cell ratio

Approximately 1 neuron for every 9 neuroglial cells in nervous tissue.

Cerebrospinal fluid

Fluid produced by ependymal cells lining the ventricles of the brain and central canal of the spinal cord.