General Body Structures: The Skin

Study Notes

General Body Structures

The Skin

Composed of two main layers: Epidermis (outer, non-vascular epithelial layer) and Dermis (deeper, vascular layer).
Epidermis contains melanin, which gives skin its color.
Dermis includes hair follicles, sweat glands, mammary glands, blood vessels, nerves, and lymphatics.

Functions of the Skin

Contains nerve receptors for sensations of pain, temperature, and touch.
Acts as a protective barrier for underlying body structures.
Regulates body temperature through various mechanisms.

Superficial Fascia

Lies directly beneath the skin, made of a fibrous network filled with fat.
Thickness varies by body region; thicker in areas like the scalp and palm, thinner in areas like eyelids.
Contains blood vessels, lymph vessels, nerves, hair roots, and glands such as sweat and mammary glands.

Functions of Superficial Fascia

Provides protection to underlying tissues.
Serves as insulation to maintain body temperature.
Contributes to body contour and fat storage.
Enables movement of skin over underlying structures.

Deep Fascia

A bluish, inelastic layer that sits beneath the superficial fascia.
Forms a tight covering around limbs and sheaths around muscles.

Functions of Deep Fascia

Stabilizes underlying structures.
Sends intermuscular septa to bones for support.
Acts as a pulley for tendon movement.
Becomes thick in areas like the palm and sole, forming palmar and plantar aponeuroses.

The Skeleton of the Human Body

The skeleton is the rigid support structure, classified into two main parts: Axial and Appendicular.

Axial Part

Comprised of the skull, vertebral column, thoracic cage, and bony pelvis.

Appendicular Part

Composed of bones in the upper and lower limbs.

The Bones

Bones are solid, living connective tissues formed of a matrix with calcified lamellae.

Types of Bones by Structure

Compact Bone: Solid outer layer of flat and short bones, and cylinders of long bones.
Cancellous (Spongy) Bone: Found in the diploe of flat bones, inner mass of short bones, and terminal ends of long bones.

Types of Bones by Shape

Long Bones: Cylindrical shape found in limbs; includes humerus, radius, and ulna.
- Composed of two ends (epiphyses) of cancellous bone and a central shaft (diaphysis) of compact bone surrounding a medullary cavity.
- Medullary cavity serves as the main blood-forming organ (bone marrow).
Metaphysis: Region where diaphysis and epiphysis meet, involved in bone growth and development.

Description

This quiz explores the general body structures, focusing specifically on the skin. It covers the epidermis and dermis layers, their functions, and accessory structures like hair follicles and sweat glands. Test your knowledge on the biology and anatomy of the skin.