INTEGUMENTARY SYSTEM *due to orientation of collagen fibers

*important in scarring
FUNCTIONS:  LAYERS OF DERMIS
1. Protection- water loss, microbes, UV light. Papillary layers
2. Sensation- hot, cold, pain, pressure  Thin connective tissue layer that contains blood
3. Temperature Regulation- helps maintain homeostasis vessels
4. Excretion- removes waste  Dermal papillae:
5. Vitamin D Production- UV light stimulates production *projections that extend up into
SKIN FACTS epidermis
1. Weighs 9 lbs. *remove waste and help regulate body temp.
2. To determine body fat (skinfold measurement) *ridges on hands and feet (fingerprints)
3. 40-56 days normal skin cycle. Every 19 days mitosis *pattern is genetically determined
4. Stratum corneum 25 or more layers Reticular layers
5. Elastic fibers lose elasticity in growing old  Deepest layer of dermis
6. Less sebum secretion (dry and fragile skin)  Accounts for 80% of dermis
7. 2 main regions: epidermis and dermis.
EPIDERMIS Structures present in the dermis
 1ST major skin region (outside)  Glands (sweat and sebaceous)
 Composed of stratified squamous epithelium  Arrector pili muscle
 Keratinization- process in which new cells push old cells to  Nerve endings
surface.  Blood vessels
-40-56days for new cells to reach surface  GLANDS
 STRATA OF EPIDERMIS Sebaceous Glands
Stratum Corneum  Connected to hair follicle
 outermost layer of epidermis  Sebum: oily substance that lubricates hair and skin to
 20-30 layers of dead squamous cells filled with prevent dying
keratin Eccrine
 Accounts for 75% of epidermal thickness  All over body and open into sweat pores
 Dandruff is the layer flaking off from scalp  Water and salt secretions
Apocrine Sweat Glands
Callus  Open into hair follicle
 Forms when stratum corneum has frequent  Only in armpits and genitalia
friction  Thick, rich secretions
 Transition layer: *Stratum Lucidum (clear layer)  Become active during puberty and cause body odor
*Stratum Granulosum(granular)  HAIR MUSCLES
*Stratum Spinosum (spinous) Arrector Pili:
 Smooth muscle that surrounds each hair follicle
Stratum Basale  Contracts and hair stands on end (goose bumps)
 Deepest layer of epidermis CUTANEOUS RECEPTORS
 Single layer of low columnar cells RECEPTOR SENSATION LOCATION
 Firmly attached to dermis Free nerve endings Itch; hot; cold; Around hair follicles;
 Made up of mitotically active cells nociception(pain) throughout skin
 SPECIALIZED CELLS & STRUCTURES IN THE EPIDERMIS Merkel’s discs light touch (very Base of epidermis
 Keratinocytes- produce keratin sensitive but not (stratum basale)
 Melanocytes- produce melanin discriminative) &
 Hair superficial pressure
 Nail Ruffini corpuscles Sustained pressure Deep in dermis
 SKIN PIGMENTS Meissner’s Fine, discriminative Upper dermis
Melanin corpuscles touch; changes in (papillary layer)
 Produced by melanocytes texture; slow
 Ranges from yellow to reddish-brown to black vibrations
 Responsible for hair and eye color Pacinian corpuscles Deep pressure; fast Deep in dermis &
 Protection against UV light vibrations hypodermis
 Amount produced determined by genetics, UV
light hormones HYPODERMIS
 Freckles are accumulation of melanin  Below dermis
 Albinism is absence of melanin  Foundation of skin
DERMIS  Attaches skin to underlying muscle and bone
 2ND major skin region  Contains loose and adipose tissue
 Dense irregular connective tissue  Contains ½ of body’s fat
 Contains collagen and elastic fibers  Body fat for females 20-23%, males 13-25%
 Contains fibroblasts, nerve endings, smooth muscle, VITAMIN D PRODUCTION
glands, blood vessels, and hair follicles. 1. UV light causes skin to produce a precursor molecule of Vitamin
 Cleavage lines: *area where skin is most resistant to D
stretching
2. Precursor is carried by blood to liver where it is modified
3. Next to kidneys where it is modified again to form active 2. Short Bones- Is cube shaped; usually located in wrist and ankle
vitamin D. joints.
4. Vitamin D can also be ingested through fish oils, fortified milk, Functions: (provides stability and some movement)
eggs and butter
5. Vitamin D stimulates intestine to absorb calcium and phosphate 3.Flat Bones- somewhat flattened that can provide protection and
(bone growth and muscle function) large areas of attachment for muscles; mostly found in the skull
(occipital, parietal, frontal, nasal, lacrimal and vomer), thoracic cage
SKELETAL SYSTEM (sternum and ribs), and pelvis (ilium, ischium and pubis)
The skeletal system has six (6) main functions: Function: (protects the internal organs)
- Support
- Movement 4.Irregular Bones- complex shape; vary in structures and therefore
- Protection do not fit into any category of other types of bones (long, short, flat
- Blood cell production or sesamoid)
- Storage Function: major mechanical support for the body and also protect
- Endocrine Regulation internal organ

SUPPORT PROVIDE FRAMEWORK FOR 5.Sesamoid Bones- small, round bones that are commonly found in
THE ATTACHMENT OF MUSCLES tendons of hands, knees and feet; embedded in tendons.
AND OTHER TISSUES Function: (protect tendons from stress and wear)
MOVEMENT Serves as points of attachments
for the muscles, and acting as (According to location)
levers.
PROTECTION Protect internal organs from 6.Sutural bones (Wormian bones) -very small bones located
injury by covering or specifically within the sutural joints between cranial bone; "extra
surrounding them. bone pieces" ; classified by location.
BLOOD CELL PRODUCTION Hematopoiesis or the
production of blood cells, occurs
in the red marrow found within
the cavities of certain bones.
STORAGE Serve as reservoir for calcium
and phosphorus, and other
essential minerals for various
cellular activities throughout the
body.
ENDOCRINE REGULATION Helps control our sugar or
energy metabolism and weight.

TYPES OF SKELETON:
1. HYDROSTATIC SKELETON
 Formed by a fluid-filled compartment within the
body, called the coelom PARTS OF A LONG BONE:
 Found in soft-bodied animals such as sea EPIPHYSIS
anemones, earthworms, Cnidaria, and other -are expanded articular ends
invertebrates. - separated from the shaft by the epipyseal
 Movement is provided by the muscles that plate during bone growth
surround the coelom. - composed of spongy bone surrounded by a
2. EXOSKELETON thin layer compact bone
 External skeleton that consists of a hard a. Proximal Epiphysis
encasement on the surface of an organism -enlarged terminal part of the bone
 It's acellular, so it must be periodically shed - rest the center of the body
because it doesn't grow as the organism grows. b. Distal Epiphysis
3. ENDOSKELETON - enlarged terminal part of the bone
 Consists of hard, mineralized structures located - farthest from the center of the
within the soft tissue of organisms. body
 Provide support for the body, protect internal METAPHYSIS
organs, and allow movement through - part of the bone between the epiphysis
contraction of muscles attached to the skeleton and diaphysis
TYPES OF BONES: - it contains the connecting cartilage
(According to shape) enabling the bone to grow
- disappears at adulthood
1. Long Bones - usually located in the appendicular skeleton and
include bones in the lower and upper limbs. DIAPHYSIS
Function: Supports weight and facilitate - elongated hollow central portion of the
bone located between the metaphysis
- made of compact tissue stage from the connective tissue. This process is
- encloses the medullary cavity known as ‘intramembranous’ or ‘direct ossification’
 Endochondral or Indirect Ossification
STRUCTURE OF A LONG BONE: - bones (e.g. short bones) are formed from the
cartilaginous model of the future bone developed in
 Articular cartilage the embryo, being dissolved and replaced by bone
- smooth resistant elastic tissue covering the terminal cells.
part of the bone - most bones are formed this way.
- facilitates movement and absorbs shocks.
 Blood vessel
- channel in the bone through which the blood
circulates, carrying the nutrients and mineral salts the
bone required.
 Bone marrow
- Soft substance contained in bone cavities, producing
blood cells
- Red in children, yellow in the adults
 Periosteum
- Fibrous membrane rich in blood vessels that
envelopes the bone
- Contributes especially to the bone’s growth in
thickness.
- Anchored to the bone itself by bits of collagen called
Sharpey’s perforating fibers
 Concentric Lamellae
- Bony layers of osteon made of collagen fibers
- Arranged concentrically around the haversian canal
- Form as the bones grow
 Osteon
- Elementary cylindrical structure of the compact bone  Intramembranous Ossification
- Runs parallel to longest axis of bone - During intramembranous ossification, compact and
- Surrounds and opens into haversian canal spongy bone develops directly from sheets of
 Haversian canal mesenchymal (undifferentiated) connective tissue.
- Lengthwise central canal of osteon The flat bones of the face, most of the cranial bones,
- Enclose blood vessels and nerves and the clavicles (collarbones) are formed via
 Volkmann’s canal intramembranous ossification.
- Perforating canal
- Transverse canals of the compact bone enclosing
blood vessels and nerves
- They connect the haversian canals and with the
medullary cavity and the periosteum
 Medullary cavity
- Cylindrical central cavity of the bone containing the
bone marrow
- Encloses lipid-rich yellow bone marrow

PHYSIOLOGY OF THE SKELETON

 The skeletal system is the body system composed of
bones, cartilages, ligaments and other tissues.
 Bone tissue, or osseous tissue, is a hard, dense connective
tissue that forms most of the adult skeleton, the internal
support structure of the body.
• Cartilages
- a semi-rigid form of connective tissue, provide flexibility
and smooth surfaces for movement
- composed of cells, chondrocytes located in the lacunae TYPES OF JOINTS
surrounded by intercellular matrix 1. SYNARTHROSES / FIBROUS JOINT (immovable)
 Ligaments a. Syndesmosis
- a short band of tough, flexible fibrous connective tissue b. Sutures
which connects two bones or cartilages or holds together a c. Gamphoses
joint. 2. AMOHIARTHROSES / CARTILAGINOUS JOINT (Slightly
- densed connective tissue movable)
 Ossification a. Synchondrosis (Invertebral disc)
- is the process by which bone is formed. Some bones b. Symphysis
(e.g. the flat bones of the skull) are formed in one
3. DIARTHROSES / SYNOVIAL JOINT (Free; composed of
Synovial fluid)
a. Hinge
- Movement occurs in only one direction or one plane.
- The hinged joint in the knee is unusual because it
allows the knee to swivel, turning the foot from side
to side.
b. Gliding
- allows two or more flat or slightly rounded bones to
move easily together without friction or grinding.
- the function of a gliding joint is to allow motions such
as smooth sliding of bone past bone, bending,
stretching and circular motion.
c. Pivot (rotary joint)
- Allows only rotary movement around a single axis
- The moving bone rotates within a ring that is formed
from a second bone and adjoining ligament.
d. Ellipsoidal/ Condyloid
- Permits movement in 2 planes, allowing flexion,
extension, adduction, abduction and circumduction.
e. Saddle
- Is a synovial joint where one of the bones forming the
joint is shaoed like a saddle with the other bone
resting on it like a rider on a horse.
- Provides stability to the bones while providing more
flexibility than a hinge or gliding joint.
f. Ball and Socket
- A partially spherical end lies in a socket, allowing a
multidirectional movement and rotation.

 TENDONS- holds the muscle to the bone

 LIGAMENT- holds the bone to the other bone.