Human Physiology Lecture Notes

Difference between Primary and Secondary Myofilaments – Comparison Table


primary vs secondary myofilaments

Primary Myofilaments vs Secondary Myofilaments
(Difference between the Primary Myofilaments and Secondary Myofilaments of Myofibrils)

Myofilaments are the filaments of myofibrils (myofibrils are the basic structural unit of muscle cells). The myofilaments are composed of proteins particularly actin and myosin. The detailed structural analysis shows that the muscle sarcomere composed of bundles of two types of myofilaments called primary myofilaments and secondary myofilaments. The present post discusses the difference between the Primary Myofilaments and Secondary Myofilaments with a comparison table.

Learn more: Difference between A-Band and I-Band

Difference between Primary and Secondary Myofilaments

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Zoology lecture notes and study materials

Difference between Keratinized and Non-keratinized Epithelial Tissues


Keratinized vs Nonkeratinized Epithelium

Keratinized vs Non-keratinized Epithelium
Difference between Keratinized and Non-keratinized Epithelial Tissues

Epithelium constitutes the outer layer of body surfaces, linings of the alimentary canal and the walls of hollow structures. It covers the internal or external surfaces of the body.

The functions epithelial tissue is to protect the underlying tissues from physical damages, infection, desiccation, UV radiation and heat loss. Based on the presence of Keratin, the epithelial tissues are categorized into Keratinized epithelium and Non-keratinized epithelial tissues.

Keratins are a diverse group of structural proteins that form the intermediate filament network and they provide the structural integrity of keratinized epithelial cells.

The present post discusses the Difference between Keratinized and Non-keratinized Epithelial Cells.

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Human Physiology Lecture Notes

Difference between A-Band and I-Band of Sarcomere – Comparison Tab


A-band vs I-band

A-Band vs I-Band
Difference between A-Band and I-Band of a Sarcomere

The basic structural and functional unit of a striated muscle is called the Sarcomere. The sarcomere is the repeating units of a striated muscle occur between two Z-lines. This gives the striated appearance of the skeletal or cardiac muscles. The sarcomere composed of myofibrils, an array elongated contractile protein threads found in striated muscle cells.

There are two types of myofibrils in the sarcomere called thin filaments and thick filaments. The thin filaments are made of protein called Actin and the thick filaments are made of proteins called Myosin. The actin and myosin filaments in a sarcomere are arranged in a specific manner so that their overlapping and interlocking patterns produce distinct bands when they are observed under a microscope. These bands are technically called as A-bands (Anisotropic) and I-Bands (Isotropic).

The present post discusses the Difference between A-bands and I-bands with a comparison table.

Sarcomere diagram

Structure of Sarcomere (Source: Wikipedia)

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Human Physiology Lecture Notes

Difference between Cilia and Microvilli – Comparison Table


cilia vs microvilli

Cilia vs Microvilli
Difference between Cilia and Microvilli

Cilia and microvilli are special types of protuberances from the surface some eukaryotic cells with specific functions such as movement, sensory functions or facilitating absorption.

Cilia (singular – Cilium) are narrow and long hair like protuberances from the apical surface of some epithelial cells. Cilia are made up of microtubules with a length of 5 to 10 µm and 0.2 µm in diameter.

Microvilli (singular – Microvillus) are microscopic cellular membrane protrusions that increase the surface area for absorption. Numerous microvilli together act as a structure called ‘Brush Borders’. The brush borders are abundantly present on the epithelial cells of the small intestine where they facilitate the absorption.

what if cilia and microvilli

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Human Physiology Lecture Notes

Difference between Rod Cells and Cone Cells (Comparison Table)


Rod cells vs cone cells

Rod cells vs Cone Cells
Similarities and Differences between Rod Cells and Cone Cells

Rod cells and Cone cells are the two types of photoreceptor cells found in the retina of eyes. These cells are capable of absorbing light and converting the light into signals that can trigger a change in the membrane potential, which results in visual phototransduction. In other words, these cells assist in vision in presence of light.

Rod cells: A type of photoreceptor cells in the eye found concentrated at the outer edges of the retina. Rod cells are responsible for vision in low light conditions.

Cone cells: The second type of photoreceptor cell in the eye concentrated in the fovea of the retina. Cone cells are responsible for the vision in bright light and colour vision.

rod vs cone cells

image source: wikipedia

The present post explains the similarities and differences between Rod cells and Cone cells with a comparison table.

Similarities between Rods and Cones

Ø  Both rods and cones are photoreceptor cells of the eye.

Ø  Both can absorb photon (light)

Ø  Both cells possess photoreceptor proteins to absorb the photons (light).

Ø  Both are modified nerve cells.

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