Integumentary System Overview

The process where skin cells harden and flatten, accumulating keratin to form a protective layer.

The outermost layer of the epidermis, composed of dead, keratinized cells that protect the body.

The deepest layer of the epidermis where new skin cells are created.

The integumentary system protects the body from UV light, microorganisms, and water loss.

The most abundant epidermal cells, responsible for producing keratin for skin strength.

Epidermal cells producing melanin, a pigment determining skin color.

Protection, sensation, temperature regulation, Vitamin D production, and excretion are all key functions of the integumentary system.

The skin has three main layers: epidermis, dermis, and subcutaneous.

Directions in skin where elastic and collagen fibers are more densely packed, influencing surgical incisions.

Layer beneath the skin containing loose connective tissue, adipose (fat) tissue, and other cells, providing insulation and padding.

Hair protects the skin, insulates, and is important for sensation.

Determined by the amount and type of melanin.

Skin glands that secrete oil to lubricate hair and skin

Hardened keratin plates at the ends of the fingers and toes.

Skin's role in maintaining body temperature including sweating and changes in blood flow to the skin.

Melanin protects against UV radiation, hair and nails provide physical barriers, and other structures provide additional protection in areas like the eyes & nose

As we age, blood supply to the skin decreases, making it harder for the body to regulate temperature.

The decrease in elastic fibers in the skin during aging causes wrinkles, as the skin loses its ability to bounce back.

The inorganic component of bone matrix is hydroxyapatite, made of calcium and phosphate, giving bone its hardness and strength.

Osteoblasts are cells responsible for building and mineralizing the bone matrix, creating new bone tissue.

Osteocytes are mature bone cells trapped within the matrix they create. They maintain the bone tissue.

There are three types of cartilage: hyaline cartilage, fibrocartilage, and elastic cartilage, each with different properties and functions.

Chondroblasts are cells that produce the matrix of cartilage, the material that gives it structure and resilience.

The perichondrium is a double-layered membrane surrounding most cartilage, providing nutrients and support.

The sliding filament model describes how muscle fibers contract. Actin filaments slide over myosin filaments, shortening the sarcomere without changing the length of the individual filaments.

A motor unit is a single motor neuron and all the muscle fibers it innervates. When a motor neuron fires, all its associated muscle fibers contract.

Calcium ions bind to troponin, which moves tropomyosin off the active sites on actin filaments. This allows myosin heads to bind to actin and initiate the power stroke.

The resting membrane potential is the electrical charge difference across the cell membrane when a cell is not actively transmitting a signal. The inside of the cell is typically more negative than the outside.

Depolarization is a change in the membrane potential, making the inside of the cell less negative. If it reaches a threshold, an action potential is triggered.

Repolarization is the return of the membrane potential to its resting state after depolarization. It occurs as positive ions flow out of the cell.

Excitation-contraction coupling is the process by which an electrical signal (action potential) leads to a mechanical response (muscle contraction).

In muscle contraction, the power stroke is the movement of the myosin head, pulling the actin filament towards the center of the sarcomere.

The electrical charge difference across the muscle fiber membrane when it is relaxed, with the inside being more negative than the outside.

A protein pump in the muscle fiber membrane that actively transports sodium ions out of the cell and potassium ions into the cell, maintaining the resting membrane potential.

The mechanical response of a muscle fiber to a single action potential along its motor neuron.

A muscle contraction where the muscle length remains the same but tension increases.

A muscle contraction where the muscle length changes but tension remains constant.

A single motor neuron and all the muscle fibers it innervates and controls.

The process of increasing force by activating more motor units within a muscle.

Muscle fibers that contract slowly, are fatigue-resistant, and have good blood supply.

Muscle fibers that contract quickly, are powerful, and fatigue easily.

ATP is the energy currency used for muscle contraction, powering the attachment and detachment of myosin heads from actin, and the active transport of calcium.

Osteoclasts are specialized cells that break down bone tissue, a process called bone resorption. They release enzymes that digest bone matrix and release calcium into the bloodstream.

The ongoing process of bone formation by osteoblasts and bone breakdown by osteoclasts, which allows bones to adapt to stress and maintain calcium levels.

The balance of calcium levels in the blood, maintained by bone remodeling, where osteoblasts deposit calcium into bone, and osteoclasts release calcium from bone.

Long bones have a shaft (diaphysis) made of compact bone, a hollow center (medullary cavity) filled with yellow marrow, and ends (epiphyses) made of spongy bone covered by compact bone.

The epiphyseal plate is a cartilaginous growth plate located at the ends of long bones responsible for longitudinal growth. Once ossified, it becomes the epiphyseal line.

Direct bone formation from mesenchymal cells. It occurs in flat bones like the skull and clavicle.

Bone formation using a cartilage model. Most bones develop this way, starting with a cartilage template that is replaced by bone.

Compact bone is dense and strong, forming the outer layer of bones. Spongy bone has a porous structure, providing strength and housing red marrow.

The central axis of the skeleton, including the skull, vertebral column, and rib cage. It protects vital organs and provides support for the trunk.

The bones of the limbs and their attachments to the axial skeleton, including the pectoral girdle, upper limbs, pelvic girdle, and lower limbs.

Sagittal, coronal, and lambdoid are sutures that join the bones of the skull. These fibrous joints allow slight movement during birth and growth.

Atlas (C1) is the first cervical vertebra, supporting the skull. Axis (C2) allows for head rotation.

True ribs attach directly to the sternum. False ribs attach indirectly or not at all.

Freely movable joints, characterized by a joint capsule, synovial fluid, and articular cartilage.

Flexion: decreasing the angle between bones. Extension: increasing the angle between bones.