Exam 3: Chapter 5 and 6

Osteopenia

reduced bone mass below normal

Vitiligo

A chronic disorder characterized by partial or complete loss of melanocytes from patches of skin producing irregular white spots. The loss of melanocytes is related to an immune system malfunction where antibodies attack melanocytes.

Fractures

A fracture is a break in a bone. Many different types of fractures may occur. The healing process involves 3 different phases in 4 steps.

Bone deposition

Additional of minerals and collagen fibers to bone by osetoblasts At a given time about 5% of bone is being remolded Helps strengthen bones, can help to reshape bone

Bones

Bone is an organ made up of several different tissues (bone, cartilage, dense connective tissue, adipose, and nervous tissue) working together. The entire framework of bones and their cartilages constitute the skeletal system. The study of bones is termed osteology.

Osteoporosis

Bone resorption outpaces formation, 80% of those affected are women

Bones and Calcium Homeostasis

Bones store 99% of the body's calcium. Osteoclasts are stimulated to increase bone resorption and calcium is released. PTH also stimulates the production of calcitriol by the kidneys to increase calcium absorption in the intestines.

Osteoarthritis

Degeneration of articular cartilage, leads to friction of bone against bone

Bone structure

Diaphysis (bone shaft) 2 epiphyses (both ends of the bone at the joints) 2 metaphyses (region between diaphysis and epiphysis) Articular cartilage covering both epiphyses Periosteum (connective tissue surrounding the diaphysis) Medullary cavity (hollow space within diaphysis) Endosteum (thin membrane lining the medullary cavity)

Layers of skin

Epidermis - the most superficial layer Dermis - a layer deep to the epidermis Hypodermis - also called the subcutaneous (subQ) layer; located deep to the dermis but not a layer of the skin; composed of areolar and adipose tissue

Aging and Bone Tissue

From birth through adolescence, more bone is produced than is lost during remodeling. In adults, the rates are the same. Older individuals, especially post-menopausal women, experience a decrease in bone mass when resorption outpaces deposition.

Compact Bone

Good at providing protection and support; strongest, few spaces in its composition, resists strain placed by weight and movement

Hair growth stages

Growth stage - cells of matrix divide. Regression stage - hair moves away from blood supply in papillary and follicle atrophies. Resting stage - old hair root falls out; new growth begins

Functions of the skin

Helps the body maintain its temperature. Converts inactive vitamin D to its active form. Provides sensory information. Helps maintain homeostasis in a number of ways.

wound healing

Inflammatory Phase - clot forms Migratory Phase - clot becomes a scab Proliferative Phase - growth of epithelial cells beneath scab Maturation Phase - scab sloughs off once epidermis restored

Types of ossification

Intramembranous - bone forms directly within the mesenchyme Endochondral - bone forms within hyaline cartilage that develops from mesenchyme

Major types of cells in the epidermis

Keratinocytes - helps protect the skin from abrasions and burns. Melanocytes - pigment producing cells of the body. Intraepidermal macrophages (Langerhans cell) - arise from red bone marrow & participate in immune response to things that invade the skin. Tactile epithelial cells (Merkel cell) - these are the sensory corpuscles that detect touch sensations.

Spongy Bone

Lightweight and provides tissue support; also called trabecular or cancellous bone, always on the interior of a bone, covered by compact bone

Nails

Nails are made of keratinized epidermal cells. Nail structures. Nail root is buried in the fold of the skin. Nail bed sits below the nail plate.

Bone remodeling

Ongoing replacement of old bone tissue by new bone tissue.

Bone Formation

Ossification (osteogenesis) is the process of bone formation. Bones form in 4 situations: During embryological and fetal development When bones grow before adulthood When bones remodel When fractures heal

bone cells

Osteoprogenitor cells (bone stem cells able to differentiate into the other types of cells) Osteoblasts (bone-building cells that secrete matrix; initiate calcification, remember Blasts Build) Osteocytes (mature bone cells) Osteoclasts (remodel bones and cause them to release calcium; bone resorption)

Blood and Nerve Supply of Bone

Periosteal arteries (accompanied by nerves) enter the diaphysis through Volkmann's canals. They are accompanied by periosteal veins. A nutrient artery enters the center of the diaphysis through a nutrient foramen. Nutrient veins exit via the same canal. Some bones only have one major artery entering to provide nutrients, while other larger bones have many. The metaphyses and epiphyses also have their own arteries and veins.

Functions of the skeletal system

Provides support. Protects the internal organs (brain, heart, etc.) Assists body movements (in conjunction with muscles). Mineral homeostasis - stores and releases calcium and phosphorus. Participates in blood cell production (hemopoiesis) RBCs, WBCs, and platelets. Stores triglycerides in adipose cells of yellow marrow.

Bone reabsorption

Removal of minerals and collagen fibers from bone by osetoclasts.

Rickets and Osteomalacia

Rickets and Osteomalacia - inadequate calcification of extracellular bone matrix. Rickets affects children and leads to bowed legs and deformations in skull, rib cage or pelvis. Osteomalacia affects adults and causes painful/tender bones and fractures with minor trauma.

Skin glands

Sebaceous (oil) glands are connected to hair follicles Some glands open directly to the surface of the skin (i.e. lips). Sudoriferous glands are sweat glands -Eccrine are the most numerous (skin, forehead, palms) -Apocrine are located mainly in hairy skin areas (armpits, groin) Ceruminous glands are modified sweat glands located in the ear canal.

Pressure ulcers

Shedding of epithelium caused by a deficiency of blood flow to tissues occurs

The dermis

The dermis is composed of connective tissue containing collagen and elastic fibers (can stretch and recoil easily)

The Epidermis

The epidermis is composed of four layers in thin skin and five layers in thick skin. They are (from deep to superficial): The stratum basale The stratum spinosum The stratum granulosum The stratum lucidum (only present in thick skin) The stratum corneum

Albinism

The inherited inability to produce melanin. Results in complete or partial absence of pigment in the skin, hair, and eyes.

Parts of the hair

The parts of a hair include: The shaft (above the skin surface) The follicle (below the level of the skin) A root that penetrates into the dermis -Epithelial root sheath -Dermal root sheath

Repair of Bone Fracture

The reactive phase is an early inflammatory phase. The reparative phase includes formation of a fibrocartilaginous callus first and a bony callus second. The bone remodeling phase is the last step as the bony callus is remodeled.

Skin cancer

The three major types are basal cell carcinoma (78%), squamous cell carcinoma (20%) and malignant melanoma (2%).

Burns

Tissue damage caused by excessive heat, electricity, radioactivity, or corrosive chemicals that denature (break down) the proteins in the skin cells

Aging

Wrinkles Dehydration and cracking Sweat production decreases The numbers of functional melanocytes decrease which results in gray hair and atypical skin pigmentation Subcutaneous fat is lost and skin thickness decreases Nails may become more brittle

Skin pigmentation

You are genetically predisposed to amount of melanin in your skin. Melanin - produced by melanocytes in the stratum basale Pheomelanin (yellow to red) Eumelanin (brown to black) Hemoglobin - red pigment in red blood cells Carotene - yellow-orange pigment stored in the stratum corneum and adipose tissue

Osteosarcoma

bone cancer that primarily affects osteoblasts

Hair (pili)

composed of dead, keratinized epidermal cells; primary functions are protection, reduction of heat loss, and sensing light and touch

Osteomyelitis

infection of bone often caused by Staphylococcus aureus.

The Integumentary system consists of:

skin, hair, oil and sweat glands, nails, and sensory receptors