Hair is a keratinous filament growing out of the epidermis. It is primarily made of dead, keratinized cells. Strands of hair originate in an epidermal penetration of the dermis called the hair follicle. The hair shaft is the part of the hair not anchored to the follicle, and much of this is exposed at the skin’s surface. The rest of the hair, which is anchored in the follicle, lies below the surface of the skin and is referred to as the hair root. The hair root ends deep in the dermis at the hair bulb, and includes a layer of mitotically active basal cells called the hair matrix. The hair bulb surrounds the hair papilla, which is made of connective tissue and contains blood capillaries and nerve endings from the dermis.
Thick myosin filaments of muscle are associated with the characteristics of contractility.
Explanation:
The muscle contractility is provided mainly the thick and the thin muscle filaments. Thick muscle filaments are constituted by the contractile protein, myosin. Thin filament is composed of actin.
Owing to its thickness, myosin protein is made up of six chains of polypeptides with four lighter (molecular mass is low) ones and two heavier (molecular mass is high) ones.
The two heavier polypeptide chains twist together like two twisted golf clubs and forms a coiled-rod like structure. This coiled structure looks like a two stranded double helix.
The globular heads point out from the main body in each coiled structure and adheres with the head of the actin filaments. The tails made up of lighter chains point towards the M lines of the sarcomere.
During muscle contraction, the myosin head will attach with its myosin-binding site.
Axon, dendrite
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