test 2 Flashcards
explain why the skin is considered an organ?
provides first impression
most vulnerable
exposed to radiation, infection, trauma, chemicals
more medical treatment than any other organ
largest and heaviest organ
describe the major functions of the skin
*resistance to trauma and infection,
*other barrier functions like UV rays, water,
*Vitamin D synthesis
*Sensation, many nerve endings such as touch, pressure, pain and vibration
*thermoregulation, altering blood flow to release or retain heat
*non-verbal communication like facial expressions
Stratum corneum
20-30 rows of flat, keratinized dead cells
accounts for 3/4 of epidermal thickness
though dead, cells still function to:
prevents water loss
accounts for most of thickness
protect from abrasion
stratum basale
attached to the dermis. bottom layer of the epidermis. consists of a single row of actively dividing cells; daughter cells rise to surface of skin
cells die as they move to surface, others remain in basale as stem cells
stratum granulosum
last living layer ; cells flatten; no longer dividing; too far from dermal capillaries to survive
nuclei and organelles disintegrate. keratinization begins
stratum spinosum
eat bacteria
*serveral layers thick
contain prekeratin filaments-allows them to resist tension and pulling.
keratinocytes in this layer appear spikey so they are called prickle cells
Stratum lucidum
couple cell layers thick
found only in thick skin
thin, translucent band
clear, flat, dead keratinocytes
epidermis
top layer, the skin
superficial region
only epithelial tissue
avascular(gets its blood supply from below)
dermis
underlies epidermis; mostly fibrous connective tissue, vascular,
gives skin strength and elasticity
*location of sensory nerves, cells, glands
hypodermis
contains nerves, blood and lymph vessels, Rich in adipose (50% of total body fat)
anchors skin to underlying structure
primary cells of epidermis
keratinocytes
produces a protein called fibrous keratin which…
makes skin hydrophobic and strong… so you don’t swell up in a pool
melanocytes
synthesize melanin, located in melanosomes. they are transferred keratinocytes, where they protect DNA from UN damage
dendritic cells
macrophages that patrol
tactile cells; sensory receptors that sense light touch… such as a bug crawling on you
thick skin contain ___ layers
5 Come lets get sun burnt
Stratum corneum
Stratum Lucidum
Stratum Granulosum
Stratum Spinosum
Stratum Basale
thin skin has ___ layers
4 Come get sun Burnt
Stratum Corneum
Stratum Granulosum
Stratum Spinosum
Stratum Basale
Where are dead skin cells located
Stratum corneum
Where is mitosis taking place ?
Stratum Basale
a row of columnar cells
What role do the melanocytes play?
they provide pigmentation and thus protection for UV rays
what role do the keratinocytes play
they play multiple roles essential for skin repair
chief role is to produce keratin, the fibrous protein the helps give the epidermis its protective properties
what are the four different cell types of the epidermis
keratinocytes
melanocytes
dendritic cells
tactile cells
primary cells of epidermis
protective properties
tightly connected by desmosomes
keratinocytes
melanocytes
synthesize melanin
melanosomes are transferred to keratinocytes -they protect DNA from UV damage
Dendritic Cells
control deeper layers of epidermis-key activation of immune system
Tactile Cells
sensory receptors, sense light touch
first degree burns
top layer of skin, epidermis
redness, slight edema(swelling) and pain in heals in days
Second degree burns
partial thickness burns-involves parts of dermis. blistered, pain
possible scars
weeks or months to heal
third degree burns
all of epidermis, all of dermis and often subcutaneous(hypodermis)
not painful-too deep. no nerve endings left
need skin grafts, fluid replacement, infection control, supplements and nutrition
the dermis has two layers
1. Papillary
above
finger-like
very loose, not a lot of fiber, plenty of wiggle room
rich in small blood vessels
the dermis has two layers
2. Reticular
below
deep to papillary
deeper, thicker layer of dermis
composed of dense irregular connective tissue
damaged dermal blood vessels may cause blister ( shoe friction etc)
the integumentary system consists of ..
hair, skin, nails, sweat glands, oil glands
cells change by going through apoptosis
controlled cell death
dead cells slough off as dander and dandruff
humans can shed 50,000 cells a minute
excessive sun exposure causes
elastic fibers clump, causing skin to become leathery
can depress immune system causing alterations in DNA which causes cancer
UV light destroys folic acid (B9) so it can be harmful to embryo
in the reticular dermis, collagen fibers run parallel to the skin, so…
incisions are made along these cleavage lines
it also helps it to heal naturally
striae
stretch marks caused by extreme stretching of skin that causes dermal tears
hypodermis, subcutaneous tissue
contains more areolar and adipose tissue than the dermis
pads body and binds skin to underlying tissues
common site of drug injections due to many blood vessels
subcutaneous fat:
energy reservoir
thermal insulation
thicker in women
thinner in infants, elderly
hair matrix
mitotically active cells immediately above the papilla; growth center for the hair
shaft is..
root is…
shaft is above skin surface
root is below skin surface
arrector pili muscle
stand straight )-bundle of smooth muscle attaching hair follicle to dermis-contract to make hair stand on end (PILOERECTION)
it is a sensory nerve and gives goosebumps
eccrine sweat glands
most numerous skin glands-3-4million in adult skin, especially dense on palms, soles, and forehead
_produce watery perspiration that helps cool the body
apocrine sweat glands
groin and region axilla
produce sweat that is milky and contains fatty acids
inactive until puberty
responds to stress and sexual stimulation
disagreeable body odor
usually bad hygiene
ceruminous sweat glands
modified apocrine glands
lining of external ear canal; secrete cerumen (Earwax)
sebacious (oil) glands
widely distributed except for palms and soles
mostly develop from hair follicles and secrete into hair follicles
relatively inactive until puberty; stimulated by hormones, especially androgens(male)
secrete sebum
oily secretion
bacterial killing properties
softens hair and skin
nail plate
hard part of nail, includes overhanging free edge, nail body(visible attached part) , and nail root over underlying skin
nails
clear, hard derivatives of stratum corneum
skin color pigments-melanin
only pigment made in skin
more sun=more protection=more melanin produced
different amounts of melanin result in different skin tones
FUNCTIONS OF BONE(SKELETAL)
- Blood cell formation
- triglyceride (fat) storage
- Hormone production
- Support
- Protection
- Movement
- Mineral and Growth Factor Storage
Describe the structure of a long bone
Diaphysis-the shaft of long bones are tubular in shape and consist of compact bone surrounding central medullary(marrow) cavity that is filled with yellow marrow in adults
Epiphysis-ends of long bones that interact at a joint
Articular (Hyaline) cartilage covers articular (joint) surfaces
Bone membranes
Periosteum
white membranes that covers external surfaces except for joints
-contains many nerve fibers and blood vessels
-anchoring points for tendons and ligaments
Bone membranes
Endosteum
connective tissue membrane covering internal bone surfaces (medullary cavity)
-cover trabeculae of spongy bone
-lines canals that pass through compact bone
WHAT IS AN OSTEOGENIC CELL
actively dividing stem cells
located in the periosteum and endosteum.
can differentiate into osteoblasts or bone lining cells when appropriate
what are osteoblasts
the bone builders
bone forming cells that secrete bone matrix called osteoid
osteoblasts are actively dividing (MITOTIC)
what are osteocytes
The monitor
mature bone cells_no longer dividing
Maintain bone matrix and act as stress or strain sensors
Communicate information
to osteoblasts and osteoclasts(cells that break down bone) so bone remodeling can occur
What are osteoclasts?
the bone crushers
come from the same stem cell line that produce macrphages
Function in bone resorption (breakdown of bone)
Osteon is…
the structural unit of compact bone-cylinder
Spongy (trabecular) bone is …
Organized along stress lines
Trabeculae, like cables, confer strength to bones
Organic components of bone include…
cells and osteoid
-osteoid contains collagen and ground substance. contributes to flexiblity and strength
Inorganic components of bone are…
mostly hydroxyapatite-a mineral salt with calcium phosphates.
makes bones extremely hard
WHAT IS OSSIFICATION?
the process of how bone tissue forms
bone tissue formation begins in month 2 of development-prenatal
postnatal(after birth) bone growth occurs until early adulthood
there are two types of ossification
endochondral
iintramembranous
how are endochondral and intramembranous different?
endochondral ossification-start out as a cartilage-through the use of bone cells , replace the cartilage with bones. this is most of our bones
intramembranous ossification(within a membrane)- forms our clavicle and most of the skull.
embryonic
form within embryonic tissue, they deposit matrix which becomes bone
Wolfe’s Law
bones grow or remodel in response to stress (demands) placed on them
LONG BONES
longer than they are wide (femur, humerus, tibia
short bones
almost equal in length and width(bones in wrist, ankles and heel bone
flat bones
mostly in skull, sternum, scapulaei
irregular bones
vertebra and chip bones, asymmetrical (back bone, hips, skull
Girdles attach limbs to…
axial skeleton, pectoral and pelvic
(pectoral) shoulder girdle
axial skeleton
in the center, midline of the body
skull, vertebral column, rib cage
appendicular (appendages)
upper and lower limbs
OSTEOPOROSIS
A GROUP OF DISEASES IN WHICH BONE RESORPTION EXCEEDS DEPOSITION, CAUSING BONE MASS TO DECLINE
affects 30% of women 60-70
affects 80% of women over 80
STRESS FRACTURE
break caused by trauma to a bone. example in a fall
pathological fracture
break in a bone weakened by disease(such as bone cancer or osteoporosis
usually caused by a stress that would not normally break a bone
fractures classified by structural characteristics
displaced and non-displaced
fractures -cracked or in multiple pieces..
comminuted or greenstick, spiral, compound, and transverse
PTH parathyroid hormone
produced in response to low blood calcium levels
stimulates osteoclasts to resorb(breaks down) bone
-calcium is released into blood, raising levels
PTH secretion stops when hoomeostatic calcium levels are reached
calcitonin
produced by thyroid gland in response to high levels of blood calcium
-inhibits osteoclasts and stimulates osteoblasts
