JNTU B.Pharmacy I Year HUMAN ANATOMY AND PHYSIOLOGY-I Previous Question Paper (June-2022 - R17)

The skin, or integumentary system, consists of three primary layers: the epidermis, dermis, and hypodermis (subcutaneous layer).

The epidermis is the outermost, avascular layer composed of stratified squamous epithelium. It contains keratinocytes (providing protection) and melanocytes (producing melanin for UV protection). The dermis lies beneath, containing connective tissue, blood vessels, nerve endings, hair follicles, and sweat glands. The hypodermis consists of adipose tissue, acting as an insulator and energy reserve.

Key functions include: 1) Protection: Acts as a physical barrier against pathogens, UV radiation, and mechanical injury. 2) Thermoregulation: Regulates body temperature through sweat production and vasodilation/vasoconstriction of dermal blood vessels. 3) Sensation: Contains sensory receptors for touch, pressure, pain, and temperature. 4) Excretion: Eliminates small amounts of waste products via sweat. 5) Synthesis: Facilitates the production of Vitamin D upon exposure to sunlight.

Joints (articulations) are classified based on their structure (binding material) and function (range of motion).

Structural Classification:

1. Fibrous joints: Bones held together by dense fibrous connective tissue (e.g., sutures in the skull).
2. Cartilaginous joints: Bones joined by cartilage (e.g., intervertebral discs).
3. Synovial joints: Bones separated by a fluid-filled joint cavity, enclosed by a fibrous capsule (e.g., knee, shoulder).

Functional Classification:

1. Synarthrosis: Immovable joints (e.g., sutures).
2. Amphiarthrosis: Slightly movable joints (e.g., pubic symphysis).
3. Diarthrosis: Freely movable joints, which are all synovial joints (e.g., hinge, ball-and-socket joints).