the skin, the largest organ in the body by weight, and its various accessory structures
How does the integumentary system maintain homeostasis?
- first line of defense
- body temperature regulation
- vitamin D synthesis
- houses immune cells
- excretion of wastes
Layers of the skin
hypodermis (subcutaneous layer/superficial fascia)
Characteristics of the epidermis
- most superficial layer of the skin
- made up of epithelial tissue
- has a basement membrane
Characteristics of the dermis
- layer of the skin deep to the epidermis
- mostly composed of connective tissue
Characteristics of the hypodermis
- deep to the dermis
- mostly adipose tissue connecting skin to its underlying layers
Layers of the epidermis
- stratum corneum: many layers of dead, keratinized cells
- stratum lucidum: found only on the palms of hands and the soles of feet
- stratum granulosum
- stratum spinosum
- stratum basale: adjacent to the basement membrane and nourished by dermal blood vessels
pigment of the skin
What is the function of melanin?
Melanin absorbs UV light to protect surrounding cells.
How is melanin produced?
Melanin is produced by melanocytes in the stratum basale from the amino acid tyrosine in organelles called melanosomes.
How is melanin dispersed?
Melanin pigment is extended out through upward extensions into the epidermis between the epithelial cells. Granules of melanin are then transferred to other cells through cytocrine secretion.
What genetic factors determine skin color?
- how much melanin is produced and distribution of melanocytes
- dark skin: granules of melanin are single and large
- light skin: granules of melanin are in clusters of two to
four and are smaller
- albinism: mutant melanin genes produce nonpigmented
What environmental factor determines skin color?
UV light darkens existing pigment and stimulates the production of more
What physiological factors determine skin color?
- blood in the dermal vessels adds color to the skin
- well oxygenated, skin appears pinkish or flushed
- low oxygen, skin appears blueish, a condition called
- state of blood vessels
- dilated, skin is reddish
- constricted, skin is pale
- over consumption of carotene
- found in yellow vegetables
- accumulation of carotene in the adipose tissue gives skin
- liver malfunction
- yellowish cast
Layers of the dermis
- papillary region, composed of areolar connective tissue
- reticular region, mostly composed of dense irregular connective tissue
Outfoldings of the dermis that extend into the epidermis and increase surface area to deliver nutrients
What makes up the reticular region of the dermis?
- dense irregular connective tissue
- muscles: smooth muscle cells that wrinkle the scrotum and are associated with hair follicles and glands, skeletal muscle fibers anchored to the dermis in the skin of the face to allow facial expressions
- nerves: motor processes carry many impulses to dermal muscles and glands, sensory processes carry impulses away from sensory receptors
- blood vessels
- hair follicles
What is the function of nails?
Nails protect the ends of digits
What are the parts of a nail?
- a nail plate covers the nail bed
- the lunula is the most active growing region where cells divide to continually push the nail out
Where is hair present?
Hair is present on almost every part of the body except on the palms, the soles, lips, nipples, and parts of the external genitals
How is hair color created?
Genes control hair color by directing the type and amount of pigment that epidermal melanocytes produce.
the brownish-black type of melanin that produces dark hair
the reddish-yellow melanin that produces blonde and red hair
specialized epithelial cells that secrete sebum made of fat and cell debris
- sebum helps keep the skin moist
- normally secreted into hair follicles
- not found on soles of feet or palms of hands
- holocrine glands, secrete entire cells
specialized epithelial cells that secrete sweat made of water, urea, and other waste
- most numerous sudoriferous glands
- used for heat loss
- produce sweat when body temperature is elevated by environmental heat or physical exercise
- abundant on forehead, neck, and back
- carried by a tube that opens at the surface as a pore
- odor producing due to how bacteria is metabolized
- become active at puberty
- active when emotionally upset, frightened, in pain, or sexually aroused
- most numerous in axillary region, the groin, and the area around the nipples
Specialized Sudoriferous Glands
- Ceruminous Glands: secrete ear wax
- Mammary Glands: secrete milk
sensory receptors that respond to changes in the concentration of chemicals
- smell and taste
- concentrations of oxygen, hydrogen ions, glucose, and
sensory receptors that respond to pain from tissue damage
- stimulated by tissue damage or forces from mechanical, chemical, or extreme temperature changes
- made up of free nerve endings
- not present in brain
- little to no adaptation
sensory receptors that respond to changes in temperature
sensory receptors that sense mechanical forces by detecting changes that deform the receptors
mechanoreceptors that sense changes in the tensions of muscles and tendons
mechanoreceptors that sense changes in blood pressure
mechanoreceptors that sense the degree of inflation (stretch) in the lungs
sensory receptors in the eyes that respond to light energy
the raw form in which sensory receptors send information to the brain
the way our brains interpret the information sent from sensory receptors
the body's ability to create adaptations to ignore common or repetitive stimuli so it can focus on new stimuli that are of more importance
specialized cells or multicellular structures that collect information from the environment and stimulate neurons to send impulses along sensory fibers to the brain
- can be the ends of neurons or other types of cells close
sense changes in the external environment
- warm receptors: 77 F too 113 F where pain and
burning sensation would occur
- cold receptors: 50 F to 68 F where pain and freezing
sensation would occur
sense changes in the internal environment
- pH changes
- blood pressure changes
sense spatial orientation
- changes in muscles and tendons
- changes in body position
Free Nerve Endings
- the simplest receptors, common in epithelial tissues, between cells
- cause itching sensation
- called tactile corpuscles
- fine touch sensation
- abundant in hairless portions of the skin; lips, fingertips, palms, soles, nipples, genitals
- deep touch and pressure
- can be found in joints and functions in proprioception
pain that is sharp and short in duration
pain that is dull and long lasting
visceral pain that feels as if it is coming from some part of the body other than the part being stimulated
- may derive from common nerve pathways that sensory impulses from both the skin areas and the internal organs use
Where is pain originating in the heart referred to?
left shoulder or the medial surface of the arm
Where is pain from the lower esophagus, stomach, or small intestine referred to?
upper central region of the abdomen
Where is pain from the liver and gall bladder referred to?
right side of neck and right upper shoulder or anterior upper right quadrant of the abdomen
Where is pain from the lung and diaphragm referred to?
left side of neck and left upper shoulder or posterior lower left quadrant of thoracic region
What is the set point for body temperature?
37 degrees Celsius
What is the homeostatic ideal for body temperature?
The amount of heat generated is equal to the amount of heat released or used
What generates heat in the human body?
What uses heat in the human body?
Which sensory receptors detect temperature?
What gives blood its temperature regulating properties?
water, which carries a lot of heat
What do blood vessels do when body temperature rises?
they dilate to bring more blood to the surface of the skin where it can be released
What do blood vessels do when body temperature falls?
they constrict in the skin to avoid losing heat
- in extreme situations, the body will sacrifice digits
What are the means in which body heat is lost?
heat rays escape from warmer surface to cooler surroundings
- primary way body heat is lost
direct contact with a cooler surface
continuous circulation of air over a warm surface
- air does not need to be cooler than skin
as sweat or fluid (water) evaporates, it carries heat away
- air can only hold a limited amount of water vapor, making evaporation less effective in humid conditions
Segments of the population that have difficulty regulating body temperature
- people with low body fat
- the elderly
inability to release a sufficient amount of heat
inability to retain a sufficient amount of heat
blood vessels in affected tissues dilate and become more permeable, allowing fluids to leak into the damaged tissues
- blood has nutrients and white blood cells, maybe clotting
- extra fluid leaked out to wash out pathogens
- can be internal, not always visible
Signs of Inflammation
- redness, vessels dilate
- swelling, fluid leaks out of broken capillaries
- warmth, increased circulation and heat produced by metabolism in synthesis reactions to heal damaged tissue
- pain, receptors stimulated by increased pressure due to swelling and tissue damage
What does RICE stand for?
What is the major issue with any cut?
our external barrier has been compromised
Steps in Healing of Cuts
1) blood vessels broken and blood leaks out to create a clot
2) scab forms from dried clot
3) collagen fibers formed by fibroblasts pull edges together
4) growth factor stimulates cells to divide
5) phagocytic cells remove damaged tissue
6) scar forms from high density collagen fibers
First Degree Burn
- superficial partial thickness burn
- blood vessels dilate and surface may be shed
- healing occurs within a few days to two weeks, no scarring
- ex: minor sunburn
Second Degree Burn
- deep partial thickness burn
- damage to epidermis and part of dermis, causing blistering
- no scarring unless infection occurs
- ex: briefly touching an iron
Third Degree Burn
- full thickness burn
- damage to epidermis, dermis, and all accessory structures
- healing must occur from the margins of the burn where healthy tissue is or through skin grafts
Rule of Nines
the subdivision of the body into regions, each accounting for 9%, or a multiple of 9%, of the total surface area
At what percentage do severe burns get categorized as life threatening?
20% or more
Why are severe burns life threatening?
- inability to sweat
- barrier from infection is compromised
What are the changes in skin due to age?
- epidermis thins
- dermis shrinks and adipose tissue decreases, leading to wrinkling
- sebaceous glands slow secretion
- decreased hair production
- decreased nerve endings
- decreased ability to thermoregulate
- melanin production slows
- vitamin D production may slow
Epithelial Cell Cancers
- slow growing
- basal cell carcinoma
- squamous cell carcinoma
- fast growing, life threatening
- known for metastasizing
- malignant melanoma
Characteristics of Melanomas
- asymmetry, when half the mole does not match the other half
- border, when the border of the mole is ragged and irregular
- color, when the color of the mole varies throughout
- diameter, if the mole's diameter is larger than a pencil's eraser
The epidermis is composed of layers of ________ tissue.
stratified squamous epithelium
Distinguish between the epidermis and the dermis.
The epidermis is the superficial layer of the skin, composed of stratified squamous epithelium. The dermis is deep to the epidermis and is composed of areolar connective tissue, dense irregular connective tissue, and the accessory structures such as hair follicles, nails, nerves and glands.
Explain the functions of the subcutaneous layer.
The subcutaneous layer anchors the dermis to underlying organs, provides padding and protection, contains the major blood vessels that supply the skin, and contributes to thermoregulation.
Describe the function of melanocytes.
Melanocytes in the statum basale produce granules of the pigment melanin which is released into the keratinocytes of the epidermis through extension that pass upward between neighboring epithelial cells.
Discuss the function of melanin, other than providing color to the skin.
Melanin protects nearby cells by absorbing UV rays.
Explain how environmental factors affect skin color.
UV rays cause existing melanin to darken and stimulates the production of more melanin, causing the skin to darken, or tan.
Describe three physiological factors that effect skin color.
The amount of oxygen carried by the blood effects skin color. Oxygen turns the hemoglobin bright red which causes the skin to appear pinkish or flushed. Deoxygenated blood has dark red hemoglobin which causes the skin to appear blueish, a condition called cyanosis.
The condition of the blood vessels effects skin color. If they are dilated, the skin appears reddish and if they are constricted the skin appears pale.
overconsumption of carotene, found in yellow vegetables, causes carotene to build up in adipose tissue and gives the skin a yellowish cast.
jaundice, a liver malfunction, causes the skin to appear yellowish
Name the tissues of the dermis.
Areolar tissue composes the papillary region, dense irregular connective tissue composes the reticular region, smooth muscle tissue is associated with some of the accessory structures, skeletal muscle tissue is found in the face, and nerve tissue make up the motor and sensory processes.
Distinguish between a hair and a hair follicle.
A hair is the portion that extends above the surface of the skin and a hair follicle is the epithelial cells that surround the hair root below the surface.
Explain the function of sebaceous glands.
Sebaceous glands secrete sebum, a mixture of fat and cell debris, that keeps the skin moist.
The sweat glands that respond to elevated body temperature and are commonly found on the forehead, neck, and back are _____ glands.
Describe the role of the skin in promoting the loss of excess body heat.
The blood vessels near the surface dilate to lose heat through the skin. The heat is lost by radiation (the loss of heat rays to the cooler environment), conduction (the direct contact between a warm surface and a cooler one), convection (the circulation of air over a warm surface), or evaporation (as sweat or fluids evaporate, the water molecules take the heat with them).
Match each means of losing body heat with its description.
A. fluid changes from a liquid to a gas
B. heat moves from body directly into molecules of cooler objects in contact with its surface
C. heat rays escape from warmer surfaces to cooler surroundings
D. continuous circulation of air over a warm surface
C. heat rays escape from warmer surfaces to cooler surroundings
B. heat moves from body directly into molecules of cooler objects in contact with its surface
D. continuous circulation of air over a warm surface
A. fluid changes from a liquid to a gas
Distinguish between the healing of shallow and deeper breaks in the skin.
With a shallow cut, the epithelial cells on the cut's margin and stimulated to divide more rapidly than normal until the newly formed cells fill the gap. With deeper cuts, first the broken blood vessels fill the gap with blood which creates a clot. The clot becomes a scab and fibroblasts create collagen fibers that pull the edges of the cut together. Phagocytes clear out dead cells and growth factor stimulates the growth of new cells to fill the gap, pushing out the scab. Extensive production of collagen fibers will form a scar.
Distinguish between first-, second-, and third-degree burns.
First-degree burns, superficial partial thickness burns, are only in the epidermis. The skin may become reddened and the surface layer made be shed. They heal within two days to two weeks and don't leave any scarring. An example would be a minor sunburn.
Second-degree burns, deep partial thickness burns, cause damage to the epithelial layer and part of the dermis. Fluid escapes from damaged dermal capillaries, causing blisters. There isn't any scarring unless infection occurs. An example would be touching an iron.
Third-degree burns, full thickness burns, cause damage to the epidermis, dermis, and all accessory structures. Healing must occur from the edges where undamaged skin is or with the help of skin grafts.
Describe possible treatments for a third-degree burn.
Possible treatments for third-degree burns are skin grafts. Autografts take skin from an undamaged part of the body and allografts come from someone other than the person with the burn. Skin can also be cultured and grown in a lab. Another technique is to use artificial membranes composed of silicone, polyurethane, or nylon with a network of collagenous fibers.
Discuss three affects of aging on skin.
Aging causes the dermis to shrink and adipose to decrease, causing wrinkles. The epidermis also thins, making skin more fragile. Sebaceous glands decrease production, which along with the changes of the skin, cause a decrease in the ability to thermoregulate. Melanin production also slows.
A premature infant typically lacks subcutaneous adipose tissue. Also, the surface area of an infant's body is relatively large compared to its volume. How do these factors affect the ability of an infant to regulate its body temperature?
The lack of subcutaneous adipose tissue means the infant does not have an insulating layer and the large surface area of the skin means that more body heat is lost. The infant would be susceptible to hypothermia.
What special problems would result from the loss of 50% of a person's functional skin surface? How might this person's environment be modified to compensate partially for such a loss?
Dehydration, electrolyte imbalance, inability to regulate body temperature, susceptibility to infection, decreased ability to sense touch, and vitamin D deficiency.
Environmental modifications could include: aseptic environment; hydration through oral or intravenous routes; controlling room temperature; and balanced diet.
Functions of Bones
- inorganic salt storage
production of red blood cells in red blood marrow
Where is red blood marrow found?
Red blood marrow is found in spongy bone (ends of long bones, hip bones, vertebrae, skull, clavicle)
Why can't red blood cells reproduce on their own?
They do not have nuclei.
What type of inorganic salt is stored in the bones?
Calcium phosphate (hydroxyapatite)
How does calcium contribute to homeostasis?
Homeostasis is maintained with blood calcium levels. Calcium is needed for clotting, nerve impulse conduction, and muscular contraction.
ends of bones, generally wider, and the point of articulation
the bone shaft between the epiphysis on each end
tough vascular membrane made of collagen, continuous with tendons and ligaments (both dense regular connective tissue)
layer of hyaline cartilage that covers the articulating surfaces of the epiphyses
Characteristics of Compact Bone
- concentric layers of extracellular matrix, thin layers with no gaps to give extra strength
- found in the wall of the diaphysis and a thin layer surrounding the epiphysis and filled with yellow marrow
- Canal System
~ Haversian: longitudinal central canal
~ Volkmann (perforating): transverse canals
Characteristics of Spongy Bone
- wide extracellular gaps with bone cells scattered throughout the trabeculae
~ helps to lighten the bone
- no central canal, nutrients diffuse throughout
- found in epiphyses and filled with red marrow
1) begins with connective tissue sheets in layers
2) osteoblasts create a bony matrix that is spongy bone and can later turn to compact bone
3) the connective tissue forms the periosteum
4) occurs in flat, broad bones like those in the skull, clavicle
1) begins with a mass of hyaline cartilage shaped like the future bone
2) cartilage begins to decompose and the periosteum forms
3) spongy and compact bone forms, complete with osteocytes and a vascular supply
4) primary ossification center located in the center of the bone
Layers of the Epiphyseal Plate
- Zone of resting cartilage
- Zone of proliferating cartilage
- Zone of hypertrophic cartilage
- Zone of calcified cartilage
1) cells divide and thicken the plate, causing the entire bone to grow
2) cells calcify and create strong bone to replace the cartilaginous tissue
3) once ossification centers meet, the epiphyseal plate ossifies (closes)
- bone grows faster than muscle
- the four leg muscles attach to one tendon, and the bone starts growing anteriorly
- tall athletes, athletic kids
- osteoclasts resorb bone tissue, and osteoblasts replace the bone
- occurs throughout life
- the resorption and deposition of bone is highly regulated to maintain integrity of bone strength
- 3% to 5% of bone calcium exchanged each year
How is bone growth stimulated?
Growth is stimulated by sex hormones and physical stress applied to the bone.
Estrogen has more growth hormone than testosterone, which is why girls reach their maximum heights before boys.
How does Vitamin A affect bone growth?
- necessary for osteoblast and osteoclast activity during normal development
- deficiency hinders bone development
How does Vitamin C affect bone growth?
- required for collagen synthesis
- deficiency causes fragile bones
How does Vitamin D affect bone growth?
- necessary for calcium absorption
- deficiency causes bone matrix to lack calcium, softening and deforming bones
~ deficiency called rickets in children
~ deficiency called osteomalacia in adults
Where does growth hormone come from?
Growth hormone is secreted by the pituitary gland.
deficiency of growth hormone causes the long bones of the limbs to fail to develop normally
excess growth hormone before epiphyseal plates ossify causes heights in excess of eight feet
caused by an excess of growth hormone in an adult, after epiphyseal plates ossify, enlarging hands, feet, and jaw
How does thyroid hormone affect bone growth?
Thyroid hormone stimulates cartilage in the epiphyseal plate. A deficiency causes delayed bone growth.
mini-factures in the bone, not a softening
Why does osteoporosis affect women more than men?
Osteoporosis affects women more than men because of declining estrogen levels after menopause.
What areas are targeted by osteoporosis?
Targeted areas include the spine, the wrist, and the hip (neck of the femur).
Ways to combat declining bone density
- exercise (slows but does not reverse bone loss)
- calcium intake
- hormone replacement
What happens when nutrients are deficient in the blood?
If nutrients are deficient in the blood, the body takes it from the bones.
What are the steps in the healing of fractures?
1) blood from the broken vessels spreads through the damaged area and forms a blood clot (hematoma)
2) vessels dilate, causing swelling and inflammation
3) blood vessels from the periosteum invade the hematoma
4) osteoclasts remove debris
5) osteoblasts divide rapidly
6) fibroblasts form fibrocartilage
7) spongy bone matrix formed in fibrocartilage
8) bone callus replaces fibrocartilage
9) calcification continues to restore normal density
incomplete break on the convex (lateral) surface of the bend in a long bone
complete break at a right angle to the axis of the bone
incomplete longitudinal break
fracture at an angle
fragments the bone
break cause by excessive twisting
skin is broken
functional junctions between bones, also called articulations
Functional Classifications of Joints
joints classified based on movement allowed at the articulation
joint with no movement
joint that is slightly movable
freely movable joint
Structural Classifications of Joints
joints classified based on the tissue that binds the bones together
bones in close contact are held together by dense connective tissue to create a joint
Types of Fibrous Joints
- bones are bound by a sheet (interosseous membrane) or bundle (interosseous ligament) of dense connective tissue
- thin sheet of dense connective tissue called a sutural ligament
- only found between cranial bones
- cone shaped bone in a socket
- periodontal ligament to secure teeth
characterized by the presence of hyaline or fibrocartilage
Types of Cartilaginous Joints
- band of hyaline cartilage
- epiphyseal plate or first sternocostal joint
- a thin layer of hyaline cartilage attached to a pad of spongy fibrocartilage
- symphysis pubis or intervertebral discs
- most joints of the skeletal system
thin layer of hyaline cartilage that covers the articular ends of the bones in a synovial joint
Layers of the Joint Capsule
outer layer: dense connective tissue that connects with the periosteum, can be joint ligaments
inner layer: loose connective tissue, called the synovial membrane
- does not cover articular cartilage
- creates synovial fluid
space in a synovial joint, filled with synovial fluid
discs of fibrocartilage that partially or completely divide the synovial joint into two compartments
synovial fluid-filled sacs with an inner lining of synovial membrane, continuous with the synovial membrane of a joint cavity
- cushion and aid the movement of tendons that glide over bony parts or over other tendons
Inflammation of a bursa
Types of Synovial Joints
- Ball and Socket
- Condylar (Ellipsoidal)
- Gliding (Plane)
- Saddle (Sellar)
Ball and Socket Joint
- also called a spheroidal joint
- greatest range of movement
- movement on all planes
- hip and shoulder
- also called an ellipsoidal joint
- does not permit rotation
- joints between metacarpals and phalanges
- also called a plane joint
- nearly flat or slightly curved
- sliding and twisting movements
- joints in wrists, ankles, vertebrae, and the joints where ribs 2 through 7 attach to the sternum
- elbow and joints of the phalanges
- neck, interaction between atlas and axis
- connection between radius and ulna
- also called a sellar joint
- joint formed from thumb and carpal (trapezium)
Nonaxial Joint Movements
Unilaxial Joint Movements
movement in one plane
Biaxial Joint Movements
movement in two planes
Multiaxial Joint Movements
movement in all planes
extension beyond anatomical position
top of foot closer to shin
top of foot away from shin
movement away from the midline
movement toward the midline
movement around an axis
rotation of the hands and forearms so that the palms face upward or anteriorly
rotation of the hands and forearms so that the palms face downward or posteriorly
rotation of the foot so that the sole faces laterally
rotation of the foot so that the sole faces medially
moving a part forward
moving a part backward
Outer layer of fibrocartilage of an intervertebral disc
Inner elastic, gelatinous portion of an intervertebral disc
weakened annulus fibrosus causes the nucleus pulposus to move out of the central region and crowd the spinal cord
- typically occurs posteriolaterally, where the nerves run
- result from loose connective tissue (muscles, ligaments, membranes) surrounding a joint or weak musculature
- can come from:
~ previous dislocations/subluxations
~ joint sprains
~ muscle atrophy
~ hormones and late pregnancy
Stability vs. Mobility Principle
the more stable, the less mobile and vice versa
the joint is forcefully moved out of normal position and remains there
a joint is forcefully moved out of normal position but returns to the original position quickly and without corrective force application
sprains are characterized by damage to the ligaments or joint capsule surrounding a joint
Grade I Sprain
ligaments stretch, not tear
- little swelling but no bruising
- sore but no functional loss
Grade II Spain
ligaments are partially torn
- slight bruising with significant swelling
- partial functional loss (partially weight bearing)
Grade III Sprain
complete tear of the ligament
- significant swelling and bruising
- complete loss of function
painful joint disorder affecting synovial joints
What indicates the cause of arthritis in synovial fluid?
- presence of white blood cells indicates inflammation or infection depending on levels
- presence of crystals indicates gout
- autoimmune disease
- synovial membrane is inflamed and thickens
- inflammation eventually erodes away the articulating surface
- fibrous tissue replaces damaged parts
- joint movement is compromised and the joint can eventually ossify and fuse the joint
- degenerative rather than inflammatory
- can be genetic but occurs with accumulated use as age progresses
- articular cartilage begins to soften and become rough
- joint space narrows
- movement along roughened surface becomes painful and the joint can lock up
- affects joints used regularly through the lifespan
Treatments for Osteoarthritis
- nonsteroidal anti-inflammatory drugs (NSAIDs)
- cortisone injections
- visco-supplementation injection
- joint replacement
Explain how central canals and perforating canals are related.
Perforating canals contain larger blood vessels and nerves by which the smaller blood vessels and nerve fibers in central canals communicate with the surface of the bone and the medullary cavity.
Explain how the development of intramembranous bone differs from that of endochondral bone.
Intramembranous bones are the flat bones such as the skull and clavicle while most of the other bones in the skeleton are endochondral bones. Intramembranous bones start out as sheets of connective tissue while endochondral bones start out as hyaline cartilage in the shape of the bone it will become. Endochondral bones form spongy and compact bone with their accompanying structures at the same time, while intramembranous bones first form spongy bone which will later develop into compact bone. Endochondral bones have ossification centers that develop in the diaphysis and the epiphysus.
________ are bone cells in lacunae, whereas ________ are bone-forming cells and ________ are bone-resorbing cells.
Osteocytes are bone cells in lacunae, whereas osteoblasts are bone-forming cells and osteoclasts are bone-resorbing cells.
Place the zones of cartilage in an epiphyseal plate in order, with the first zone attached to the epiphysis.
Zone 1 - zone of resting cartilage
Zone 2 - zone of perforating cartilage
Zone 3 - zone of hypertrophic cartilage
Zone 4 - zone of calcified cartilage
Explain how osteoblasts and osteoclasts regulate bone mass.
Osteoblasts create new bone, while osteoclasts resorb bone material. This is a constant process throughout life, but highly regulated so that the bone mass stays balanced. About 3% to 5% of bone calcium is exchanged every year.
Describe the effects of vitamin deficiencies on bone development and growth.
Vitamin A deficiency leads to inhibited bone growth, Vitamin C deficiency leads to fragile bones, and Vitamin D leads to softened bones and deformities.
Physical exercise pulling on muscular attachments to bone, stimulates __________.
Physical exercise pulling on muscular attachments to bone, stimulates the bones to thicken and strengthen.
Describe how joints are classified.
Joints are classified by either their function, based on movement allowed at the articulation (synarthritic, amphiarthritic, diarthritic) or their structure, based on the tissue that binds the bones together (fibrous, cartilaginous, synovial).
Explain how the joints between vertebrae permit movement.
The joints between vertebrae are amphiarthrotic, so the combined joints allow the back to bend forward, back, to the side, and to twist.
Describe how a joint capsule may be reinforced.
Ligaments are used to bind the articular ends of bones together reinforcing the joint capsule. These can be thickenings in the fibrous layer of the joint capsule or accessory structures that are located outside of the joint capsule.
Explain the function of a synovial membrane.
The synovial membrane secretes synovial fluid, and fills the spaces and irregularities within the cavity.
Explain the function of synovial fluid.
Synovial fluid helps to cushion, moisten, and lubricate the smooth cartilaginous surfaces within the joint. It also supplies the articular cartilage with nutrients.
Describe the six types of synovial joints, and name an example of each type.
Ball and Socket, moves on all planes, shoulder
Condyloid, does not permit rotation, joints between metacarpals and phalanges
Hinge, moves along one plane like a door hinge, elbow and joints of the phalanges
Saddle, joint formed from thumb and carpal (trapezium)
Gliding, sliding and twisting, joints between the various bones of the wrist and ankle
Pivot, rotation on an axis, neck