Integumentary system

Epidermis

superficial layer of stratified squamous epithelial tissue

dermis

deep layer of connective tissue

subcutaneous tissue

not part of skin; loose connective tissue that connect skin to underlying structures

keratinocytes

are most cells; produce keratin for strength

melanocytes

contribute to skin color, same number in all people

langerhans cells

part of the immune system

merkel cells

detect light, touch and superficial pressure

keratinization

as cells move outward through the layers they fill with keratin, then die and serve as a layer that resists abrasion and forms permeability layer

stratum basale

deepest portion of epidermis (germinativum) and single layer of cuboidal or columnar cells

stratum spinosum

8 to 10 layers of many-sided cells that flatten as they are pushed upward

lamellar bodies

a tiny membrane-bound storage particle inside specific cells that holds and secretes vital lipids and proteins

stratum granulosum

2 to 5 layers of flattened, diamon-shaped cells; contains protein granules of keratohyalin

keratohyalin

dense protein structure found in cytoplasmic granules within the stratum granulosum of the epidermis

degenerate

progressive deterioration, loss of structure, impairment of functions in cells, tissues or organs over time

stratum lucidum

consists of 25 or more layers of dead overlapping squamous cells joined by desmosomes called cornified cells

cornified cells

dead keratinocytes that form the outermost protective barrier of the skin

thick skin (only epidermis)

had 5 epithelial strata, found in areas subject to pressure or friction (palms, fingertips)

thin skin

has 4 epithelial strata (no lucidum), more flexible, hair grows here

callus

increase in number of layers in stratum corneum. when this occurs over a bony prominence a corn forms

corn

a thickened area of the outermost layer that develops in response to repeated friction or pressure

skin color

determined by 3 factors; pigments in the skin, blood circulating through the skin, thickness of stratum corneum

melanin

provides for protection against UV light

melanocytes

specialized cell that produces melanin

melanosomes

responsible for synthesis, storage and transport of melanin

albinism

deficiency or absence of pigment

carotene

yellow pigment from vegtables; accumulates in stratum corneum, adipose cells of dermis and subcutaneous tissue

cyanosis

blue color caused by decrease in blood oxygen content

erythema

red color cause by increased blood pressure

papillary dermis

superficial, areolar, elastic fibers, dermal papillae, capillary beds; thin topmost layer that sits directly beneath the epidermis

dermal papillae

small finger-like bumps of CT that extend from upper dermis into the lower part of the epidermis

reticular dermis

deep, dense, irregular CT of collagen and elastic fibers

cleavage lines

elastic and collagen fibers oriented in some directions more than in others

stretch marks

form of dermal scar tissue caused by tearing and breakdown of connective fibers

hair shaft

protrudes above skin surface

hair root

located below surface; base of this is the hair bulb

medulla

central axis; innermost layer

cortex

forms bulk of hair

hair cuticle

forms hair surface; outer most layer protects inside of hair shaft

internal matrix

inner part of hair shaft that helps give strength and structure

hair papilla

blood supply at bottom of hair follicle

dermal root sheath

part of dermis that surrounds the epithelial root sheath

epithelial root sheath

layer that surrounds and protects the growing hair

internal epithelial root sheath

inner layer that surrounds and protects growing hair

external epithelial root sheath

outer layer that surrounds and protects hair follicle

growth stage

stage where cells added at base and hair elongates

resting stage

follicle shortens and hold hair in place, rest, then hair falls out of follicle, new hair begins

pattern baldness

hair loss that follows a common pattern, usually caused by genetics

alopecia areata

spot baldness due to an autoimmune response

arrector pili

tiny smooth muscle that makes the hair stand up and cause goosebumps

sebaceous glands

holocrine; produces sebum to keep skin and hair moisturized

sebum

oily substance that keeps skin and hair soft and moisturized

eccrine (merocrine) glands

sweat glands that produce sweat (isotonic fluid) to help cool body; crucial in body temp regulation

apocrine gland

sweat glands that release sweat into hair follicles mainly in armpits and groin

ceruminous glands

modified eccrine sweat glands in external auditory canal

cerumen (earwax)

composed of combination of sebum and secretion from ceruminous

mammary glands

modified apocrine sweat glands that produce milk

nail body

stratum corneum; visible portion of nail

eponychium (cuticle)

corneum superficial to nail body

hyponychium

corneum beneath free edge

nail matrix

area at base of nail where new cells are made

nail bed

epithelial tissue underneath the nail that supports nail as it grows, with stratum basale and gives rise to cells that form nail

nail root

covered by skin; epithelial tissue with stratum basale that gives rise to cells that form nail, extends from nail matrix

lunula

small part of nail matrix seen through the nail body as whitish crescent-shaped area at base

sensation

pressure, temperature, pain, heat, cold, touch, movement of hairs

temperature regulation

sweating and radiation, process of keeping body temp within normal range

vitamin D production

skin makes this vitamin when sunlight is absorbed

excretion

removal of waste products from the body

endochondral ossification

forms bones of the base of the skull, part of mandible, epiphyses of the clavicles, and most remaining bones of skeletal system

cartilage model formation

(week 9 embryonic) early stage of bone development where cartilage is shaped into the basic form of a future bone

bone collar formation

(month 3) layer of bone forms around outside of the cartilage model, making it more rigid

primary ossification center formation

(month 3-birth-adolescence) blood vessels enter the cartilage allowing osteoblasts to begin replacing cartilage with bone

secondary ossification center formation

(birth through adolescence) osteoblasts begin replacing cartilage with bone in the ends of the bone

adult bone

fully developed bone with most of its cartilage replaced by hard bone tissue

closure of epiphyseal plate

epiphyseal plate is ossified becoming the epiphyseal line (between 12 and 25 years of age)

articular cartilage

smooth cartilage covering ends of bones and helps reduce friction and absorb chock at joints, does not ossify, persists through life

appositional growth

growth that makes a bone wider by adding new bone tissue to its outer surface

1. Zone of resting cartilage

slowly dividing chondrocytes

2. Zone of proliferation

new cartilage is produced on the epiphyseal side of the plate as the chondrocytes divide and form stacks of cells

3. Zone of hypertrophy

chondrocytes mature and enlarge

4. Zone of calcification

matrix is calcified and chondrocytes die

5. Ossified bone

cartilage on the diaphyseal side of the plate and is replaced by bone

Vitamin D

necessary for absorption of calcium from intestines, can be ingested or manufactured in the body

Rickets

lack of vitamin D during childhood

Osteomalacia

lack of vitamin D during adulthood leading to softening of bones

Vitamin C

necessary for collagen synthesis by osteoblasts

scurvy

deficiency of vitamin C, can cause wounds not to heal and teeth to fall out

growth hormone

hormone released by the anterior pituitary that stimulates bone and body growth

thyroid hormone

requires for growth of all tissues

reproductive hormones

hormones that control sexual development, reproduction and growth changes during puberty (estrogen and testosterone)

gigantism

excessive growth hormone secretion during growing years

dwarfism

insufficient growth hormone during growing years

basic multicellular units (BMUs).

Temporary groups of osteoclasts and osteoblasts that remodel bones.

1. Hematoma formation.

Localized mass of blood released from blood vessels but confined within an organ or space. Clot formation. Bone tissue dies.

2. Callus formation.

mass of tissue that forms at a fracture site and connects the broken ends of the bone.

internal bone repair

blood vessels grow into clot in hematoma.

External bone repair

A collar forms around the outside of the bone, where cells become osteoblasts and chondroblasts to stabilize the two pieces.

3. Callus ossification.

Callus replaced by woven, spongy bone.

4. Bone remodeling

Replacement of spongy bone and damaged material by compact bone. Sculpting of site by osteoclasts.

Calcitriol

Increases blood calcium by stimulating intestinal absorption of calcium, Derived from vitamin D3.

Calcitonin

Lowers blood calcium by inhibiting osteoclast activity.