Lecture Exam 2 - A&P

Diaphysis

bone shaft

Epiphyses

Distal and proximal ends of bone

Metaphyses

Where the diaphysis and epihysis join

Articular Cartilage

thin layer of hyaline cartilage that covers epiphyses, reduces friction at joint

Periosteum

dense irregular connective tissue covering bone allowing for growth (diameter)

Medullary cavity

contains yellow marrow

Endosteum

lines medullary cavity

Osteogenic (progenitor) cells

produce daughter cells through mitotic division that will become osteoblasts

Osteoblasts

secrete matrix of bone tissue (build up)

Osteocytes

mature osteoblasts entrapped in matrix carry on exchange of waste and nutrients with blood

Osteoclasts

50 or more fused monocytes, these cells release powerful enzymes that breakdown bone in process known as resorption

Compact Bone

80% of skeleton

Provides protection and support

Arranged in osteons around a central blood supply (Haversian canal)

Lamellae

concentric rings of calcified bone, laid down around the central canal by osteoblasts

Lacunae

small, hollow spaces filled with osteocytes

Canaliculi

fingerlike prjections from lacunae that extend out to other osteocytes

Spongy Bone

20% of skeleton

Mostly made up of short, flat, and irregular bones

Reduce weight of bone and protect and support red bone marrow

Receives nourishment from medullary blood supply 

Arranged at ends of bone along lines of stress

Trabeculae

irregular lattice of columns

forms spongy bone

Nutrient artery

How the bone is fed

enters near the center of the diaphysis then branches to the proximal and distal ends

Osteogenesis

The process by whereby bone forms

Uses Intramembranous ossification and Endochondral ossification 

Intramembranous ossification

Bone is formed through the differentiation of mesenchymal cells in fibrous connective tissue

Found in flat bones of the skull

Endochondral Ossification

Bone is formed from a cartilagenous model, which gradually ossifies

Interstitial Growth

From the inside, outwards (occurs in Endochondral Ossification)

Appositional Growth

From the outside, in (occurs in Endochondral Ossification)

Periosteal bone collar (Endochondral Ossification)

A nutrient artery stimulates osteogenic cells of the perichondrium to change into osteoblasts, which secrete the periosteal bone collar

Primary Ossification Center (Endochondral Ossification)

initial site of bone formation in endochondral ossification

Proceeds inward from the outside of the bone (appositional growth)

typically located in the diaphysis of long bones

Secondary Ossification Center (Endochondral Ossification)

Appears after the primary ossification center

Located at the epiphyses (end)

Ossification proceeds outwards (interstitial)

Leaves an articulating surface of cartilage

Epiphyseal Plate (growth plate)

Created from endochondral ossification

Layer of hyaline cartilage at the end of bones between the epiphysis and diaphysis

Allows bones to grow in length

Seals around age 18-25

Epiphyseal Line

a mature epiphyseal plate

The epiphyseal plate is ossified and bone growth ceases (in adulthood)

Bone Growth 

Occurs at the epiphyseal plate in four zones 

Zone of Resting Cartilage

One of four zones along the epiphyseal plate

anchors epiphysis

Zone of Proliferating Cartilage

One of four zones along the epiphyseal plate

Dividing chondrocytes

Zone of Hypertrophic Cartilage

One of four zones along the epiphyseal plate

Chondroctes increase in size (hypertrophy)

Zone of Calcified Cartilage 

One of four zones along the epiphyseal plate

dead calcified chondrocytes, osteoclasts move in dissolving the matrix, osteoblasts begin creating new matrix

Insulin Growth Factors (IGF’s)

promote cell division at the epiphyseal plate

human Growth Factor 

stimulates IGF production 

Thyroid (T3 & T4)

Decrease in thyroxine → cretinism (impaired physical and mental development)

Increase in thyroxine → microcephaly (head size is significantly smaller than average)

Insulin

Factor affecting growth

From the pancreas

Sex Steroids

Estrogens and Androgens cause growth spurts and cause the epiphyseal plates to seal

Bone Remodeling

Redistributes bone matrix along lines of stress

Osteoclasts form leak-proof seal with ruffled border

Sex steroids slow resorption → results in increased bone deposition

Growth in Thickness

Only occurs by appositional (outside → in) growth

Compound Fracture

Through the skin

Simple Fracture

below the skin

Comminuted Fracture

Two or more pieces

Greenstick Fracture

partial fracture on one side where the bone bends

Impacted Fracture

one end of bone forcefully driven into other

Pott’s Fracture

Fracture at distal end of leg (fibula)

Colles’ Fracture

Fracture at the distal end of forearm (radius)

Stress Fracture

tiny fissures caused by strenuous excercise

Ex: running, jumping

Fracture Hematoma

Involved  in fracture repair

Formation of clot: fracture hematoma

phagocytes clean-up area of cellular debris 

Procallus

Uncallcified tissue that forms around a bone fracture

Transformes into a fibrocartilaginous (soft) callus

Serves to hold the ends of a broken bone together

Integumentary System

Consists of: skin, hair, nails, various glands, muscles, and nerves

Serves to: protect the body, maintain body temperature, provide sensory input

Epidermis

Superficial layer

Composed of stratified squamous epithelium

Composed of four types of cells:

Keratinocytes

Melanocytes

Langerhans Cells

Merkel Cells

Keratinocytes

90% of epidermis

Produce keratin: a tough fibrous protein

Produces Lamellar Granules

Lamellar Granules

Organelle of keratinocytes

makes the skin waterproof

Melanocytes

Produces pigment melanin

Protects skin against UV radiation

Albinism 

an inherited trait in which teh individual does not produce melanin (no color)

Vitiligo

A condition where lack of melanocytes produces patches of irregular white skin

Merkel Cells

Found deep in epidermis

Together with sensroy neurons they form a tactile disc

Provide sensation of touch

Langerhans Cells

Made from ________

Participate in immune response

Easily damaged by UV light

Epidermal Layers (Deep → Superficial)

Stratum Basale (Germinativum)

Stratum Spinosum

Stratum Granulosum

Stratum Lucidum (thick skin only)

Stratum Corneum

Stratum Basale (Germinativum)

Deepest layer of epidermis

Single layer of cuboidal or columnar cells

All types of epithelial cells

Bound to basement membrane by hemidesmosume

Stratum Spinosum (Spinos = thornlike)

Superficial to basal layer

Polyhedral keratinocytes held together by “spinelike” bundles of intermediate fibers inserted at desmosomes linking cells together

Provides strength and fleibility

Stratum Granulosum

Flattened layer of dying keratinocytes (apoptosis)

Contains a granular protein: Keratohyalin

Secretes Lamellar Granules whichc form a water sealant

Stratum Lucidum

Found only in “thick skin” on fingertips, palms, and soles of feet

Consists of dead keratinocytes

Makes fingerprints

Stratum Corneum (corne = hard)

Outermost epidermal lining

Composed of dead keratinocytes

Continuously sheds about every four weeks

Psoriasis

Condition where skin sheds every 7-10 days due to rapid cell division

Dermis

Made up of a Papillary Region and Reticular Region

Papillary Region (Dermis)

Areolar tissue

Composed of highly vascular infoldings to increase surface area

Contains Meissner corpuscles that are sensitive to touch

Free nerve endings sensitive to hot/cold pain and itching

Reticular Region (Dermis)

Contains collagen and elastic fibers (dense irregular)

Contains adipose tissue and accessory organs

Hair (Accessory Organ)

Found on most surface except palms and soles

consists of a shaft above the surface and a root that penetrates the dermis and subcutaneous layer

New hairs develop from cell division of the matrix in the bulb

Protects against sun, provides warmth, senses vibrations

Arrectores Pilorum Muscles 

goose bumps

Skin Glands

Sebaceous Glands, Sudoriferous Glands (sweat glands), and Ceruminous glands

Sebaceous Glands

associated with hair follicles

Secretes sebum: protects hair from drying out and keeps skin soft and pliable

Sudoriferous Glands (sweat glands)

Two types of sudoriferous glands:

Eccrine glands

Apocrine glands

Eccrine Glands (Sudoriferous)

secrete dilute fluid of electrolytes and metabolites amino acids, glucose, and lactic acid

Found throughout the body

Cool the body and remove waste

Apocrine Gland

Found in axillary regions (groin, armpits)

Secrete proteins and lipids in addition to the eccrine secretions

Attract bacteria that create body odor

Ceruminous Glands

secrete a protective waxy covering in ear

Nails (Accessory Organ)

Hard, keratinized epidermal cells over the dorsal surfaces of the terminal portions of the fingers and toes

Principal Parts: body, free edge, root, lunula, eponychium (cuticle), and matrix

Vasodilation

Radiation of hot blood 

Thermoregulation (Function of Skin)

through sweating (evaporation) and vasodilation, skin is able to regulate temperature 

Transdermal Drugs

Drugs that can be absorbed through the skin

Functions of the Skin

Thermoregulation, Protection, Excretion, Absorption, and Syn

Rickets

bone disease that occurs when body does not have enough vitamin D

Epidermal Wound Healing

Damage is superficial

Basal cells break from basement membrane and travel toward each other until they contact (contact inhibition)

Epidermal Growth Factor encourages mitotic division to replace lost cells

Deep Wound Healing

Damage to dermis and subcutaneous layer (hypodermic)

Inflammatory: Clot forms, vasodilation, differentiation

Migratory: clot becomes scab, scar tissue forms (granulation tissue)

Involves Keloid, Proliferation, and Maturation

Hypertrophic (Deep Wound Healing)

within boundaries

Keloid (Deep Wound Healing)

Raised beyond boundaries from excessive fibrosis

Scarification

practiced by tribespeople as form of adornment 

Proliferation (Deep Wound Healing)

epithelial cells growth, fibroblasts secrete collagen fibers

Maturation (Deep Wound Healing)

scab sloughs off, fibers become more organized

Burns

Involves levels of Burns:

1st Degree - 3rd Degree

Rule of Nines (Burns)

Way of assessing amount of burn damage

Divided body up into regions of 9%

1st Degree Burn

Least severe, erythema, no blisters

Involves epidermis only

Ex: sunburn

2nd Degree Burn

Involves epidermis and possible part of dermis

Blisters, edema, and redness

3rd Degree Burn

Most severe, epidermis, dermis, and accessory structures destroyed

Requires skin graft

erythema

redness

Edema 

Swelling