BIO EXAM 2

Keratinized stratified squamous epithelium

Connective tissue layer

Subcutaneous fat layer

• Resistance to trauma and infection
• Barrier to ultraviolet light
• Vitamin D synthesis
• Sensory receptors
• Thermoreceptors through sweating
• Nonverbal communication

Undifferentiated cells in deepest layers

Most of the skin cells

Synthesize pigment that shield UV

Receptor cells associated with nerve fibers

Macrophages guard against pathogens

• Single layer of cells on basement membrane
• Keratinocyte stem cells undergo mitosis to replace epidermis
• Melanocytes distribute melanin through cell processes and melanin picked up by keratinocytes
• Merkel cells are touch receptors that form Merkel disc

• Several layers of keratinocytes
• Appear spiny due to shrinkage during histological preparation
• Contains denditic (langerhans) cells
• Macrophages from bone marrow that migrate to the epidermis
• Help protect body against pathogens by presenting them to the immune system

• 3 to 5 layers of flat keratinocytes
• Contain keratinohyalin granules which combine with filaments of cytoskeleton to form keratin
• Produces lipid-filled vesicles that release a glycolipid by exocytosis to waterproof the skin
• It forms a barrier between surface cells and deeper layers of the epidermis and cuts off surface strata from nutrient supply

• Thin translucent zone seen only in thick skin
• Keratinocytes are packed with eleidin, a precursor to keratin (does not stain well)
• cells have no nucleus or organelles

• Up to 30 layers of dead, scaly, keratinized cells
• Surface cells flake off (exfoliate)

• Extensions of the dermis into the epidermis
• Forms the ridges of the fingerprints
• Layers: Papillary layer, reticular layer is deeper part of the dermis

Red pigment of red blood cells

• Yellow pigment
• concentrates in stratum corneum and fat

• Yellow, Brown, and Black hues
• Pigment synthesis stimulated by UV radiation

Blueness from deficiency of oxygen in the circulating blood (cold weather)

Redness due to dilated cutaneous vessels (anger, sunburn, embarrassment)

Yellowing of skin and sclera due to excess of bilirubin in blood (liver disease)

Birthmarks: discolored skin caused by benign tumors of dermal blood capillaries (strawberry birthmarks disappear in childhood while port wine birthmarks last for life)

• Aggregations of melanocytes
• Freckles are flat
• Moles are elevated

• Leave oily fingerprints on touched surfaces
• A unique pattern formed during fetal development

form after birth by repeated creasing of the hand, wrist, and elbow areas

Above skin

• Within follicle
• Medulla, Cortex, and Cuticle

Oblique tube within the skin

Where hair originates

Vascular tissue in bulb that provides nutrients

• Little Eumelanin
• Mostly Pheomelanin

All Eumelanin

• Little Eurmelanin
• Lots of Pheomelanin

Lack of pigment and hollow

Sweat Glands

• Produces scent of sweat
• Found only near hair follicles and respond to stress and sex
• Bromhidrosis is body odor produced by bacterial action on fatty acids

• Produces persperation
• Millions of them help cool the body

• Produce Sebum, an oily secretion that contains broken-down cells.
• Lanolin is sebum

Additional nipples that may develop along milk line

• Least dangerous
• Arises from stratus basale and invades dermis

• Arises from keratinocytes in stratum spinosum
• Metastasis to the lymph nodes can be lethal

• Most deadly
• Arises from melanocytes of a preexisting mole
• ABCD: asymmetry, border irregular, color mixed and diameter over 6 mm

Tissue from patient

Tissue from identical twin

From unrelated person

from another species

Minerals that harden the matrix of connective tissue

Lever acted upon by muscles

Glide across one another in multiple directions

Protect soft organs

• Cylinder of compact bone
• Marrow cavity lined with endosteum

Medullary Cavity

Osteogenic cells and reticular connective tissue

• Enlarged ends
• Spongy bone covered by compact bone
• Enlarged to strengthen joint and attach ligaments

Covered with articular cartilage

• Covered with periosteum
• Outer layer fibrous layer of collagen
• Inner osteogenic layer of bone forming cells

Growth plate

• Compact and Spongy Bone
• Marrow Cavity
• Articular Cartilage
• Periosteum

• External and internal surfaces composed of compact bone
• Middle layer is spongy bone and bone marrow
• Skull fracture may leave inner layer of compact bone unharmed

Bone stem cells

• in endosteum, periosteum, or central canals give rise to new osteoblasts
• Arise from embryonic fibroblasts (bone stem cells)
• Multiply continuously

Mineralize organic matter of a matrix

• Osteoblasts trapped in the matrix they formed
• Cells in lacunae connected by gap junctions inside canaliculi

• Develop in bone marrow by fusion of 3-50 blood stem cells
• Reside in resorption pits that they "eat" into the bone

1/3 organic and 2/3 inorganic

collagen, glycosaminoglycans, proteglycans and glycoproteins

• 85% hydroxyapatite (calcium phosphate)
• 10% minerals (fluoride, potassium, magnessium)

• Basic structural unit
• Cylinders formed from layers of matrix around central canal
• Osteocytes connected to each other and their blood supply by tiny cell processes in canaliculi

Layers of matrix around central canal

Central canal

• Perforating canals
• Vascular canals perpendicularly joining central canals

• plates of bone that give spongy bone spongelike appearance
• Have few osteons or central canals
• No osteocyte is far from blood of bone marrow
• Develop along bone's lines of stress

In medullary cavity (long bone) and among trabeculae (spongy bone)

Long Bone

Spongy Bone

• Like thick blood
• Reticular fibers and immature cells
• Hemopoietic (Produces blood cells)
• In vertebrae, ribs, sternum, pelvic girdle and proximal heads of femur and humerus in adults

Fatty marrow of long bones in adults

Yellow marrow replaced with reddish jelly

• Condensation of mesenchyme into trabeculae
• Osteoblasts on trabeculae lay down osteoid tisssue (uncalcified bone)
• Calcium phosphate is deposited in the matrix forming bony trabeculae of spongy bone
• Osteoclasts create marrow cavity
• Osteoblasts form compact bone at surface
• Surface mesenchyme produces periosteum
• Produces flat bones of skull and clavicle

Uncalcified Bone

Create marrow cavity

Form compact bone at surface

• Bone develops for pre-existing model; perichondrium and hyaline cartilage
• Most bones develop by this process
• Formation of primary ossification center and marrow cavity in shaft of model
• Stem cells give rise to osteoblasts and clasts
• Bone laid down and marrow cavity created

Develop bony collar

Swell and die in Enchondral ossification

Remains as articular cartilage and epiphyseal (growth) plates, which proved grown through childhood and are gone by early twenties

Hyaline Cartilage

Chondrocytes multiply forming columns of flat lacunae

Cell enlargement

Mineralization of matrix

• Chondrocytes die and columns fill with osteoblasts
• Osteons formed and spongy bone is created

• Interstitial growth and epiphyseal plate
• Epiphyseal line is left behind when cartilage is gone

• Appositional Growth
• Osteoblasts lay down matrix in layers on outer surface and osteoclasts dissolve bone on inner surface

• Wolff's Law of Bone
• Greater Density and mass of bone in athletes or manual workers is an adaptation to stress

• Architecture of bone determined by mechanical stresses
• Action of osteoblasts and osteoclasts

• Crystallization process
• Osteoblasts produce collages fibers spiraled the length of the osteon
• Minerals cover the fibers and harden the matrix
• Ions are deposited along the fibers
• Ion concentration must reach the solubility product for crystal formation to occur

Calcium and phosphate and from blood plasma

• Abnormal calcification
• May occur in lungs, brain, eyes, muscles, tendons, or arteries (arteriosclerosis)

• Bone dissolved and minerals released into blood for other uses
• Performed by osteoclasts "ruffled border"
• Hydrogen pumps in membrane secrete hydrogen into space between the osteoclast and bone surface
• chloride ion follow by electrical attraction
• hydrochloric acid dissolves bone minerals
• Enzyme digests collagen

Enzyme that digests the collage in mineral resorption from bone

• Stimulates osteoclasts to remove bone
• Decrease pressure stimulates osteoblasts

Component of DNA, RNA, ATP, phospholipids, and pH buffers

Needed in neurons, muscle contraction, blood clotting and exocytosis

• Phosphate level change = little effect
• Calcium level change = can be serious
• Homeostasis depends on calcitriol, calcitonin, and PTH hormon regulation

• Deficiency of blood calcium
• Causes excitability of nervous system if too low
• Muscle spasms, tremors, or tetany 6 mg/dl
• Laryngospasm and suffocation 4 mg/dl

• Excess of blood calcium
• Binding to cell surface makes sodium channels less likely to open, depressing nervous system
• Muscle weakness and sluggish reflexes, cardiac arrest 12 mg/dl

• Central axis
• Skull, vertebral column, ribs, sternum and sacrum

Limbs and girdles

Scapula and clavicle

Clavicle attaches medially to the sternum and laterally to the scapula

• Should joint
• Scapula articulates with the humerus
• easily dislocated due to loose attachment

Arm = Humerus

Forearm = Radius and ulna (Radius is on the thumb side)

Wrist = 8 small bones in 2 rows

• Hand = 19 bones in 2 groups
• 5 metacarpals in palm
• 14 phalanges in fingers

• Form the wrist
• Allow for flexion, extension, abduction and adduction
• 2 Rows/4 Bones Each
• - Proximal row = scaphoid, lunate, triquetrum and pisiform
• -Distal row = trapezium, trapezoid, capitate and hamate

Proximal, middle and distal phalanx

Base, shaft, and head

2 Hip Bones

Girdle and Sacrum

• Supports trunk on the legs and protects viscera
• Each os coxae is joined to the vertebral column at the sacroiliac joint
• Anteriorly, pubic bones are joined by pad of fibrocartilage to form pubic symphysis