Aim: Microscopic study of muscular and nervous tissue
Reference:
- Tortora, G. J., & Derrickson, B. H. (2018). Principles of Anatomy and Physiology (15th ed.).
Wiley. - Kandel, E. R., Schwartz, J. H., & Jessell, T. M. (2013). Principles of Neural Science (5th
ed.). McGraw-Hill Education.
Muscular Tissue
Muscular tissue is specialized tissue in animals that facilitates movement and force generation
through contraction. It is essential for various physiological functions, including locomotion,
maintaining posture, respiration, and circulation. Muscular tissue comprises elongated cells
called muscle fibers, which contain actin and myosin filaments, the primary proteins responsible
for muscle contraction.
Types of Muscular Tissue
Skeletal Muscle
Structure: Skeletal muscle is made of long, cylindrical, multinucleated fibers with a striated
(striped) appearance due to the arrangement of actin and myosin filaments.
Location: Attached to bones via tendons.
Function: Responsible for voluntary movements, such as walking, writing, and facial
expressions.
Control: Voluntary, controlled by the somatic nervous system.
Cardiac Muscle
Structure: Cardiac muscle fibers are short, branched, and typically contain one or two nuclei.
They also display striations and contain intercalated discs, which allow synchronized
contraction.
Location: Found only in the heart.
Function: Pumps blood throughout the body by rhythmic, involuntary contractions.
Control: Involuntary, controlled by the autonomic nervous system and influenced by hormonal
signals.
Smooth Muscle
Structure: Composed of spindle-shaped, single-nucleated fibers lacking striations, giving it a
smooth appearance.
Location: Walls of hollow organs, such as the intestines, blood vessels, bladder, and uterus.
Function: Controls involuntary movements like digestion, regulation of blood flow, and bladder
control.
Control: Involuntary, regulated by the autonomic nervous system.
Functions of Muscular Tissue
Muscle contractions move body parts, stabilize posture, and produce heat to help regulate body
temperature. Cardiac muscle pumps blood, while skeletal and smooth muscles support breathing
and blood flow regulation.
Nervous Tissue
Nervous tissue is specialized tissue in the nervous system responsible for transmitting electrical
and chemical signals throughout the body. It is fundamental for sensory perception, response to
stimuli, and coordination of bodily functions. Nervous tissue consists primarily of neurons, the
signaling cells, and glial cells, which provide structural and functional support to neurons.
Structure of Nervous Tissue
Neurons
Cell Body (Soma): Contains the nucleus and organelles, acting as the metabolic center of the
neuron.
Dendrites: Short, branched extensions that receive signals from other neurons and relay them to
the cell body.
Axon: A long, singular projection that transmits impulses away from the cell body to other
neurons or effector cells (e.g., muscles or glands).
Synaptic Terminals: Endings of the axon that release neurotransmitters, chemicals that relay
signals to the next cell across the synapse (the gap between neurons).
Neuroglia (Glial Cells)
Astrocytes: Supportive cells in the central nervous system (CNS) that regulate the extracellular
environment, supply nutrients, and maintain the blood-brain barrier.
Oligodendrocytes: Produce the myelin sheath in the CNS, which insulates axons and speeds up
signal transmission.
Schwann Cells: Similar to oligodendrocytes but located in the peripheral nervous system (PNS),
they produce the myelin sheath around PNS axons.
Microglia: Act as immune cells in the CNS, removing waste and damaged neurons.
Ependymal Cells: Line the ventricles of the brain and produce cerebrospinal fluid (CSF), which
cushions and nourishes the CNS.
Types of Nervous Tissue
Gray Matter: Composed primarily of neuron cell bodies, dendrites, and unmyelinated axons. Found in the brain’s outer layers (cortex) and deeper nuclei, as well as in the spinal cord’s central region.
Processes and integrates information.
White Matter: Consists mainly of myelinated axons, which give it a whitish appearance. Located beneath the gray matter in the brain and surrounding the gray matter in the spinal cord. Responsible for transmitting signals rapidly between different areas of the nervous system.
Functions of Nervous Tissue
Neurons detect environmental changes (e.g., touch, light, sound), and the CNS processes sensory
information to make decisions. Neurons control muscles and glands, managing movement and
secretions. Nervous tissue regulates body functions like temperature, heart rate, and blood
pressure, while the brain’s complex structure enables thought, memory, and emotions.
Nervous tissue, with its highly specialized cells and complex organization, is central to the
body’s communication system, integrating various physiological functions, regulating responses
to external and internal stimuli, and enabling higher mental functions.
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