LO2 Notecards - Chapters 5, 6

Sex hormones (estrogen and testosterone)

These begin to be secreted in great amounts at puberty, dramatically accelerate bone growth. They stimulate osteoblasts; promote epiphyseal plate growth and closure.

Short bone

These bones have a length nearly equal to their width. Their external surfaces are covered by compact bone, and the interior is composed of spongy bone. Sesamoid bones, which are tiny, seed-shaped bones along the tendons of some muscles, are also classified as these.

Irregular bone

These bones have elaborate, complex shapes and do not fit into any of the preceding categories.

First degree burn

These burns involve only the epidermis and are characterized by redness, pain, and slight edema (swelling). An example is a mild sunburn.

Third degree burn

These burns involve the epidermis, dermis, and subcutaneous layer, which often are destroyed; they are usually caused by contact with corrosive chemicals or fire, or by prolonged contact with extremely hot water.

Second degree burn

These involve the epidermis and part of the dermis. The skin appears red, tan, or white and is blistered and painful. Examples include very severe sunburns (characterized by blisters) or scalding from hot liquids or chemicals.

Parathyroid hormone

This hormone increases blood calcium levels by encouraging bone resorption by osteoclasts.

Stratum basale

This is the deepest epidermal layer. This single layer of cells ranges from cuboidal to low columnar in appearance. It is tightly attached to an underlying basement membrane that separates the epidermis from the connective tissue of the adjacent dermis. The three types of cells that occupy this layer are keratinocytes, melanocytes, and tactile cells.

Importance of calcium in the body

Transmission of nerve impulses Muscle contraction Blood coagulation

Rickets

Disease caused by a vitamin D deficiency in childhood and characterized by overproduction and deficient calcification of osteoid. Due to the lack of vitamin D, the digestive tract is unable to absorb calcium and phosphorus, the minerals needed for the hardening of the osteoid during the formation of bone.

Rule of Nines

Estimates the severity of burns, body is divided up into numbers divisible by nine. Anterior and posterior lower limbs = 36% Anterior and posterior trunk = 36% Anterior and posterior upper limbs = 18% Anterior and posterior head and neck = 9% Perineum = 1%

Fossa

Flattened or shallow depression (indentation)

Osteoblasts

Formed from osteoprogenitor stem cells; these cells often exhibit a somewhat cuboidal structure. They secrete the initial semisolid, organic form of bone matrix called osteoid. Osteoid later calcifies and hardens as a result of calcium salt deposition. They produce new bone, and once they become entrapped in the matrix they produce and secrete, they differentiate into osteocytes.

Explain the growth of a long bone

GOOD LUCK WITH THAT ONE FRIENDS!

Glucocorticoids

Group of hormones produced by the adrenal cortex. Normal levels tend not to have any major effects on bone growth or mass. However, if levels are chronically too high, they stimulate bone resorption and can lead to significant loss of bone mass.

Osteoporosis

It is a bone condition in which bone mass becomes reduced enough to compromise normal function. It is a disease that results in decreased bone mass and microarchitectural changes that lead to weakened bones that are prone to fracture.

Osteomalacia

It is a vitamin D deficiency disease in adults characterized by gradual softening and bending of the bones as a result of decreased mineral content; although bone mass is still present, it is demineralized.

Stratum corneum

It is the most superficial layer of the epidermis. It is the stratum you see when you look at your skin. This layer consists of about 20 to 30 layers of dead, scaly, interlocking keratinized cells called corneocytes. The dead cells are anucleate (lacking a nucleus) and tightly packed together.

Cells of the epidermis

Keratinocytes - produce the fibrous protein keratin Melanocytes - produce the brown pigment melanin Langerhans' cells - epidermal macrophages Merkel cells - function as touch receptors

Osteoclasts

Large, multinuclear, phagocytic cells; they appear to be derived from fused bone marrow cells similar to those that produce monocytes. They are involved in an important process called bone resorption. They remove matrix and osteoblasts add to it, maintaining a delicate balance.

Condyle

Large, smooth, rounded articulating oval structure

What type of tissue is the dermis?

Lies underneath the epidermis and consists of two types of connective tissue: areolar and dense irregular. The two major regions are a superficial papillary layer and a deeper reticular layer.

Briefly describe the lines of cleavage on the skin, and explain their clinical importance.

Lines of cleavage, or tension lines, in the skin identify the predominant orientation of collagen fiber bundles. They partition the skin and indicate the predominant direction of underlying collagen fibers in the reticular layer of the dermis. These are clinically and surgically significant because any procedure resulting in a cut at right angles to a cleavage line is usually pulled open due to the recoil from cut elastic fibers. This often results in slow healing and increased scarring. In contrast, a cut parallel to a cleavage line usually remains closed, resulting in faster healing. Therefore, surgical procedures should be planned to allow for these lines of cleavage, thus ensuring rapid healing and preventing scarring.

Sudoriferous glands (sweat glands)

Located in the skin, these produce a watery solution that performs several specific functions such as thermoregulation, secretion, and protection.

Sebaceous glands

Located in the skin, these produce an oily material that coats hair shafts and the epidermal surface. This oily, waxy secretion is called sebum and it acts as a lubricant to keep the skin and hair from becoming dry, brittle, and cracked.

Collagen fibers

Main component of the organic components of the bone

Osteocytes

Mature bone cells derived from osteoblasts that have become entrapped in the matrix they secreted. They reside in small spaces within the matrix called lacunae. They maintain the bone matrix and detect mechanical stress on a bone. This information is communicated to osteoblasts, and may result in the deposition of new bone matrix at the surface.

Summary of endochondral ossification (based on my lecture notes in class from what he wrote on the board)

Right around two months of development the ossification begins. 1. Blood vessels contact perichondrium 2. Perichondrium changes to periosteum 3. Mesenchyme starts producing osteoblasts 4. Bone collar is formed 5. Chondrocytes in the middle enlarge and calcify 6. Marrow cavity is formed 7. Primary ossification center develops (by the third month)

Foramen

Rounded passageway through a bone (hole)

What is SPF and how does it protect the skin?

SPF stands for Sun Protection Factor. It is the number determined experimentally by exposing subjects to a light spectrum that mimics noontime sun. Some of the subjects wear sunscreen while others do not. The amount of light that induces redness in sunscreen-protected skin, divided by the amount of light that induces redness in unprotected skin, equals the SPF. This means that a sunscreen with an SPF of 15 will delay the onset of sunburn in a person who would otherwise burn in 10 to 15 minutes. Thus, a sunscreen with an SPF of 15 will keep the skin from burning 15 times longer than if the skin is unprotected.

Osteoid

Semisolid, organic form of bone matrix; it later calcifies and hardens as a result of calcium salt deposition.

Stratum spinosum

Several layers of polygonal keratinocytes form this epidermis layer, also known as the spiny layer. In addition to the keratinocytes, this layer also contains the fourth epidermal cell type, the epidermal dendritic cells. These are immune cells that help fight infection in the epidermis.

Diploe

Spongy bone sandwiched between two layers of compact bone. They are found in the internal part of short, irregular, and flat bones. Its significance is that it produces red bone cells in adults.

Osteoprogenitor cells

Stem cells derived from mesenchyme; when they divide, they produce another stem cell and a "committed cell" that matures to become an osteoblast.

Thyroid hormone

Stimulates bone growth by stimulating metabolic rate of osteoblasts; too little results in short stature

Growth hormone

Stimulates the liver to produce the hormone somatomedin, which causes cartilage proliferation at the epiphyseal plate and resulting in bone elongation; too little growth hormone results in short stature in the child.

Process

Any marked bony prominence (something that sticks out)

Role of parathyroid glands

Anytime you have low calcium these release hormones to signal the body that more calcium is needed

What are the layers of the epidermis?

Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale

Two exocrine glands in the skin

Sudoriferous glands (sweat glands) Sebaceous glands

Function of bones

Support and protection Movement Hemopoiesis Storage of mineral and energy reserves

What is the basic structural component of hair and nails?

The basic structural component of both hair and nails is keratin. They are both composed primarily of dead, keratinized cells. The cells that form the nails are densely packed and filled with parallel fibers of hard keratin. Additionally, a single hair also known as a pilus, has the shape of a slender filament, and is composed of keratinized cells growing from hair follicles that extend deep into the dermis.

Which is likely to heal faster, a bone injury or a cartilage injury? Why?

The cartilage lacks blood supply, whereas the marrow in bones actually produce red blood cells. Bone is highly vascularized, especially in regions containing red bone marrow. This blood allows for more nutrients to help the bone heal faster than cartilage.

Spiral fractures

fracture spirals around axis of long bone; results from twisting stress

Intramembranous Ossification

Develops from mesenchyme to produce flat bones of the skull

General structure long bones

Diaphysis Epiphysis Metaphysis Articular cartilage Medullary marrow cavity Endosteum Periosteum

Impetigo

A contagious, pus-forming bacterial infection of the skin; fluid-filled vesicles form and then rupture, forming a yellow crust.

Athlete's foot

A fungal infection of the skin, especially between the toes; causes itching, redness, and peeling. Also called tinea pedis.

Warts

A growth of epidermal cells that forms a roughened projection from the surface of the skin; caused by human papillomavirus.

What is the perichondrium?

A layer of dense irregular connective tissue that surrounds the cartilage of developing bone. It consists of two separate layers: an outer fibrous layer and inner chondrogenic layer.

Appositional growth

A long bone's growth in width. It occurs within the periosteum. In this process, osteoblasts in the inner cellular layer of the periosteum lay down bone matrix in layer parallel to the surface, called external circumferential lamellae. These lamellae are analogous to tree rings: As they increase in number, the structure widens. Thus, the bone becomes wider as new bone is laid down at the periphery. As this new bone is being laid down, osteoclasts along the medullary cavity resorb bone matrix, creating an expanding medullary cavity. The combined effects of bone growth at the periphery and bone resorption within the medullary cavity transform an infant bone into a larger version called an adult bone.

Shingles

A skin rash characterized by blisters on red base with burning pain. Caused by the varicella-zoster virus, which causes chickenpox. After someone has had chickenpox, the virus remains dormant in the body, associated with parts of the nervous system. Emotion stress, immune deficiency, or cancer can reactivate the virus to cause shingles.

Stress fracture

A thin break caused by recent increased physical activity in which the bone experiences repetitive loads; tends to occur in the weight-bearing bones (e.g., pelvis and lower limb).

Vitamin A

Activates osteocytes

Stratum granulosum

Also called the granular layer, this layer consists of three to five layers of keratinocytes superficial to the stratum spinosum. Here is where the process of keratinization begins when the keratinocytes fill up with the protein keratin. A fully keratinized cell is dead because it has neither a nucleus nor organelles, but it is strong because it contains keratin.

What are the 3 forms of skin cancer?

Basal cell carcinoma Squamous cell carcinoma Malignant melanoma

Endochondral ossification

Begins with a hyaline cartilage model and produces the majority of bones in the body

Hydroxyapatite

Bone salt crystals formed from calcium hydroxide and calcium phosphate

Composition of bone matrix

Both organic and inorganic 1/3, or 33% is organic including cells, collagen fibers and ground substance 2/3, or 67% is minerals (inorganic material)

Psoriasis

Chronic inflammatory condition characterized by lesions with dry, silvery scales, usually on the scalp, elbows, and knees.

Stratum lucidum

Clear layer; it is a thin, translucent region about two to three cell layers thick that is superficial to the stratum granulosum. This stratum is found only in thick skin, such as the palms of the hands and the soles of the feet.

Compare compact and spongy bones in terms of structure, composition and location.

Compact bone is solid and relatively dense, whereas spongy bone appears more porous, like a sponge. The arrangement of compact and spongy bone components differs at the microscopic level. Spongy bone forms an open lattice of marrow plates of bone, called trabeculae. In a long bone, compact bone forms the solid external walls of the bone, and spongy bone is located internally, primarily within the epiphyses. In a flat bone of the skull, the spongy bone, also called diploe, is sandwiched between two layers of compact bone.

What are the two major components of the integumentary system?

Cutaneous membrane (skin) Accessory structures (nails, hair, sweat glands, and sebaceous glands).

What determines hair color?

Hair color is a result of the synthesis of melanin in the matrix adjacent to the papillae. Variations in hair color reflect genetically determined differences in the structure of the melanin. There are two types of melanin, eumelanin and pheomelanin, and they occur in various ratios of yellow, reddish, tan, brown, and black shades. Additionally, environmental and hormonal factors may influence the color of the hair. As people age, pigment production decreases, and thus hair becomes lighter in color. Gray hair results from the gradual reduction of melanin production within the hair follicle, while white hair signifies the lack of pigment entirely.

Long bone

Have a greater length than width. These bones have an elongated, cylindrical shaft (diaphysis). This is the most common bone shape.

Components of Osteon or Haversion System

Haversion canal Concentric lamellae Osteocytes Lacunae Canaliculi Perforating canals

What are the three different cartilages in the body and where are they found?

Hyaline cartilage - trachea Elastic cartilage - ear Fibrocartilage cartilage - intervertebral discs

Location of hematopoietic tissue (red marrow) in both infants and adults

In infants - found in the medullary cavity and all areas of spongy bone In adults - found in the diploë of flat bones, and the head of the femur and humerus

Two methods of ossification

Intramembranous Ossification Endochondral Ossification

How do bones respond to mechanical stress?

Mechanical stress, in the form of exercise, is required for normal bone remodeling. In response to mechanical stress, bone has the ability to increase its strength over a period of time by increasing the amounts of mineral salts deposited and collagen fibers synthesized. Stress also increases the production of the hormone calcitonin, which helps inhibit bone resorption by osteoclasts and encourage bone deposition by osteoblasts.

These three pigments contribute to skin color

Melanin Carotene Hemoglobin

What is the function of melanin in keratinocytes?

Melanin granules form a protective shield over the nuclei of the keratinocytes where it absorbs UV radiation in sunlight, thus preventing damage to nuclear DNA.

What is the effect of sunlight on skin color? Why?

Melanin is a pigment produced and stored in cells called melanocytes. Melanocyte activity affects the color of the entire epidermis. All people have about the same number of melanocytes. However, melanocyte activity and the color of the melanin produced by these cells vary among individuals and races, resulting in different skin tones. The amount of melanin in the skin is determined by both heredity and light exposure. Melanin pigment surrounds the keratinocyte nucleus, where is absorbs ultraviolet (UV) radiation in sunlight. Exposure to UV light both darkens melanin already present and stimulates melanocytes to make more melanin.

Flat bone

Named because they have flat, thin surfaces. These bones are composed of roughly parallel surfaces of compact bone with a layer of internally placed spongy bone.

Eczema

Noncontagious skin inflammation often characterized by itchy, red vesicles that may be scaly or crusty.

Epicondyle

Projection adjacent to a condyle

Four zones involved in endochondral ossification

Proliferation Zone Hypertrophy Zone Calcification Zone Ossification Zone

Vitamin D

Promotes absorption of calcium and phosphate into blood; helps with calcification of bone

Vitamin C

Promotes collagen production

Major functions of the integumentary system

Protection Prevention of water loss Temperature regulation Metabolic regulation Immune defense Sensory reception Excretion

What is the difference between thick and thin skin?

The difference between thick skin (400 to 600 micrometers thick) and thin skin (75 to 150 micrometers thick) is that all five epidermal strata occur in thick skin. Thick skin contains sweat glands, but no hair follicles or sebaceous glands. While thick skin is found on the palms and the hands, the soles of the feet, and corresponding surfaces of the fingers and toes, thin skin is found covering most of the body. In thin skin the epidermis lacks the stratum lucidum, so it has only four layers.

Hemopoiesis

The formation and development of blood cells

What is acne? What causes it, and what are the treatment methods?

The term acne describes plugged sebaceous ducts. Acne may become abundant beginning at puberty, because increases in sex hormone levels stimulate sebaceous gland secretion, making the pores more prone to blockage. However, any age group can have acne. There are different treatment methods available for acne depending on its type and severity. Some medicinal treatments include but are not limited to are benzoyl peroxide (used as a treatment for mild acne, it has antibacterial properties and appears to decrease the secretion of some sebum components), salicylic acid (helps unclog pores and appears to affect the rate of skin cell shedding), topical and oral antibiotics (many forms of acne are filled with bacteria therefore the use of antibiotic helps prevent acne outbreaks), topical retinoids (essentially vitamin A-like compounds that are effective against acne; they help normalize the abnormal growth and death of cells in the sebaceous glands), and systemic retinoids (similar to topical retinoids, but are taken orally; very effective for treating even the most severe forms of acne; associated with major birth defects, so women who are pregnant or thinking to become pregnant should not take this drug).

Squamous cell carcinoma

arises from keratinocytes of stratum spinosum; lesions usually appear on scalp, ears, lower lip, or back of hand; early lesions are raised, reddened, scaly; later lesions form concave ulcers with elevated edges; treated by early detection and surgical removal of lesion; may metastasize to other parts of the body.

Complete fracture

bone is broken into two or more pieces

Comminuted fracture

bone is splintered into several small pieces between the main parts

Avulsion

bone or bone fragments accompany soft tissue as it is pulled from its origin or insertion

Four different types of bone (based on their shape)

long bone short bone flat bone irregular bone

Basal cell carcinoma

most common type of skin cancer; least dangerous type because it seldom metastasizes; originates in stratum basale; first appears as small, shiny elevation that enlarges and develops central depression with pearly edge; usually occurs on face; treated by surgical removal of lesion.

Malignant melanoma

most deadly type of skin cancer due to aggressive growth and metastasis; arises from melanocytes, usually in preexisting mole; individuals at increased risk include those who have had severe sunburns, especially as children; characterized by change in mole diameter, color, shape of border, and symmetry; survival rates improved by early detection and surgical removal of lesion; advanced cases (metastasis of disease) are difficult to cure and are treated with chemotherapy, interferon therapy, and radiation therapy. The usual signs of melanoma may be easily remembered using the ABCD rule: Asymmetry, Border, Color, and Diameter.

Greenstick

partial fracture; convex side of bone breaks, the other side is bent