HAP- exam 2 study guide

Epithelial Tissue (Epithelium)

• 2 types (by location)

  • Covering/lining

    • external/internal surfaces

  • Glandular

    • secretory tissue in gland

Functions of Epithelial Tissue

• physical protection

• selective permeability

• secretions

• sensations

Epithelial Tissue- Physical Portection

• Protects from dehydration, abrasion, destruction

Epithelial Tissue -Selective permeability

• Allows passage of some subtsnaces while preventing passage of others

Epithelial Tissue - secretions

• Some cells specialized to secrete

Epithelial Tissue - Sensations

Supply information to nervous system

Characteristics of epithelial tissue

• Cells have polarity—apical (upper, free) and basal (lower, attached) surfaces

  • Apical surfaces may bear microvilli (e.g., brush border of intestinal lining) or cilia (e.g., lining of trachea)

  • Noncellular basal lamina of glycoprotein and collagen lies adjacent to basal surface

Types of cells

• Squamous

• Cuboidal

• Columnar

Layers

• Simple

• Stratified

Simple columnar epithelium Function

• Absorption

• secretion of mucus

• enzymes , and other substances

• ciliated types propels mucus (or reproductive cells ) by ciliary action

Simple columnar epithelium location

• along the lines of most digestive tract ( stomach to anal canal )

• gallbladder

• excretory ducts of some glands

Stratified squamous epithelium function

• protects underlying tissues in areas subjected to abrasion

Stratified squamous epithelium location

• moist linings of esophagus , mouth, and vagina

Loose connective tissue

• fewer fibers, more ground substance

  • areolar

  • adipose

  • reticular

Dense connective tissue

• more fibers , less ground substance

  • dense regular

  • dense irregular

  • elastic

Support connective tissue - cartilage

• hyaline

• fibrocartilage

• elastic

Supporting connective tissue Bone

• compact

• spongy

Fluid connective tissue

• Blood

• Lymph

Major functions of connective tissue

• binding/ support

  • ligaments/tendons

• Protection

  • bones of cranium, fat for kidneys

• Storage

  • fat for energy, bone for calcium/ phosph.

• Transportation (blood)

Structural elements of connective tissue

• cells

• fibers

• ground substance

Collagen fibers ( white )

• strongest/ most abundant type

• 25% of body’s protein

• provides high tensile strength

Elastic

Networks of long, thin, elastin fibers that allow for stretch (skin, arteries)

Reticular fibers

• Short, fine, highly branched collagenous fibers

• abundant in the stroma of lymph nodes/ livers

Ground Substance

• Nonliving material

  • medium through which solutes diffuse b/t blood capillaries and cells

  • solid/semisolid

  • viscous

Loose connective tissue

• Wraps/ cushions organs

• plays important role in inflammation

• holds/conveys tissue fluid

Dense Irregular connective tissue

• able to withstand tension exerted in many directions; provides structural strength

• major cell in fibroblast

Supportive connective tissue - Resist Compression

• No role in fat storage or disease Matrix 80% water ( why it can resist compression

Hyaline

• Supports/ reinforces

• has resilient cushioning properties

• resist compressive stress

  • located in costal cartilages

What is the bodies Largest Organ ?

• Skin

  • covers 1.5→ 2.0 m2

  • Composes 15% of body weight

Another name for skin is the ______ membrane

• Cutaneous

Functions of skin

• Resistance to trauma/ infection (protection)

• immune defense

• vitamin D(3) synthesis (metabolic reg)

• sensation

• thermoregulation

• nonverbal communication

Thick Skin

• Covers front of hands, bottoms of feet

  • epidermis 0.5 mm thick

Thin Skin

• covers rest of the body

  • epidermis about 1.0mm thick

Epidermis what layer

• Outer layer of skin

Dermis what layer

• inner layer beneath epidermis

Epidermis

• 05-.1mm thick

• Made up of stratified squamous epithelial cells.

• Provides a protective barrier against environmental
  damage (like pathogens, UV radiation, and water loss).

• Constantly renews itself through cell division at the base and shedding at the surface.

• How often do we shed ours epidermis?

  • You lose about 30,000 to 40,000 skin cells every minute, which adds up to millions per day

Keratinocytes

• Most abundant cells in the epidermis.

• Produce keratin, a tough protein that provides protection and waterproofing.

• Form multiple layers as they move from the base to the surface

Dendritic Cells (Langerhans cells)

• Immune cells that detect and fight pathogens.

• Found in the stratum spinosum.

• Act like sentinels, alerting the immune system to invaders.

Tactile Cells (merkel Cells)

• Located in basal layer

• Connected to nerve endings / help detect touch/pressure

• important for sensory perception

Melanocytes

• also found in basal layer

• Produce melanin, pigment gives skin its color

• protect against UV radiation by absorbing harmful rays

Stem cells (basal cells )

• Found in the stratum basale (deepest layer).

• Continuously divide to produce new keratinocytes.

• Essential for skin regeneration and repair

The dermis

• 4mm thick

• Composed of connective tissue, rich in collagen and elastin fibers.

• Contains blood vessels, nerve endings, hair follicles, sweat glands, and sebaceous (oil) glands.

• Provides strength, elasticity, and nutrients to the skin.

• Supports thermoregulation and sensory perception
  
  

Hypodermis

• Subcutaneous tissue

  • has more areolar/adipose than dermis has

Subcutaneous fat

• energy reservoir

• thermal insulation

Integumentary system

• Largest organ in body

  • nails

  • hair

  • sebaceous oil glands

  • sweat glands

Hair

• Hair found almost everywhere on the body

• Keratinized cells form slender filament

• Grows from hair follicles

Hair 3 types

• lanugo

• vellus

• terminal hair

Lanugo

• fine, unpigmented, downy hair. Appears in last trimester

Vellus

• fine hair

• Primary human hair

• Found on upper and lower limbs

Terminal Hair

• coarser, pigmented, longer

• On scalp, eyebrows, eyelashes, beards

• During puberty, replaces vellus hair in axillary and pubic regions

3 zones of a hair follicle

• hair bulb

• root

• shaft

Hair matrix

• keratinization

• new cells divide

• pushed up

Hair follicle

• oblique tube around root

• extends down to dermis

Hair functions

• protection

• heat retention

• sensory

Burns

• Major cause of accidental death

• Caused by heat, radiation, chemicals, sunlight, electrical shock

• Threat to life from fluid loss, infection, effects of burned tissue

1st degree burns

• involve only epidermis

• slight redness/pain

• immerse burned area in cool water

2nd degree burns

• involve epidermis/ part of dermis

• skin blistered /painful

• slight scarring

3rd degree burns

• involve epidermis, dermis, and subcutaneous layer

• Require hospitalization

• Treatment for dehydration and infection

• Require additional caloric intake

• Severe scarring

• May need debridement and skin graft

Skeletal System

• composed of bones, cartilages, and ligaments

  • bone

  • cartilage

  • ligaments

    • tendons- attach muscle to bone

Bone is ________ and contains mainly ________ nerves.

• highly vascularized

• sensory nerve

Types of bones

• compact

• spongy

ligaments

• Connect bone to bone

Tendons

• connect muscle to bone

The bones of the fingers and toes (phalanges)
are categorized as _____ bones.
A) long
B) irregular
C) short
D) flat
E) sesamoid

• A) long

Long bone

humerus

Short bone

talus

Flat bone

Sternum

Irregular bone

• Vertebra

General Features of bones

• Epiphysis Diaphysis, Metaphysis

• Compact and spongy bone

• Marrow cavity

• Articular cartilage

• Periosteum

Epiphyseal plate/line

Bone Marrow

• bone marrow

• red marrow (myeloid tissue)

• yellow marrow

Bone cells: Osteoblast

• under endosteum/periosteum

• synthesize organic matter of bone matrix

• nonmitotic

Osteocytes

• former osteoblast in matrix

• reside in lacunae

• cytoplasmic process that reach into canaliculi

• connect to osteoblasts

• importance of canals

Oseteoclasts

• ruffled border

• increase cell surface area

• reside in pits: resorption bays

Bone matrix: Ground substance/ fibers

• Bone matrix has Organic and inorganic components

• organic compounds

  • Osteoid produced by osteoblasts

Histology of Osseous Tissue

Compact bone

Osteon Structural Unit

Growth of Cartilage

• Interstitial Growth

  • occurs within internal regions of cartilage

• Appositional Growth

  • occurs on cartilage’s outside edge

Bone Development

• Ossification or Osteogenesis- the formation of bone

• in human fetus/ infant, bone develops by 2 methods

• intramembranous

• endochondral

Intramembranous Ossification

• bone growth within a membrane

• produces:

  • flat bone of skull

  • some of facial bones

  • mandible

  • central part of clavicle

Endochondral Ossification

• Within cartilage model

• most bones of skeleton

  • long bones

Step 1 of long bone development in limb

• fetal hyaline cartilage model develops

  • chondroblasts secrete cartilage matrix during 8th→12th week of development

Step 2 of long bone development in limb

• Cartilage calcifies. a periosteal bone collar forms

  • chondrocytes in cartilage model produce holes in matrix

  • Matrix calcifies, chondrocytes die

    • produces calcified cartilage shaft with large holes

Step 3 of long bone development in limb

• Periosteal; bud extends from periosteum into cartilage shaft , growth of capillaries /osteoblasts

• Osteoblasts produce osteoid on calcified cartilage template

  • primary ossification center

• Bone development extends in both directions toward epiphyses

Step 4 of long bone development in limb

• Secondary ossification centers form in epiphyses

  • hyaline cartilage calcifies / degenerates

  • blood vessels / osteoprogenitor cells enter

  • secondary ossification centers form

Step 5 of long bone development in limb

• Bone replaces cartilage, except articular cartilage/ epiphyseal plates

Step 6 of long bone development in limb

• Lengthwise growth continues until epiphyseal plates ossify/ form epiphyseal lines

Lengthwise bone growth continues into puberty

• growth continues until epiphyseal plate is converted to epiphyseal line indicates bone has reached adult length

• Occurs between ages of 10 and 25

Bone remodeling

• Continues throughout adulthood

• Occurs at different rates

• 20% of skeleton replaced yearly

• Dependent upon the coordinated activities of osteoblasts, osteocytes, and osteoclasts

• Influenced by hormones and mechanical stress

Bone growth/ remodeling

• Ossification continues throughout life with the growth and remodeling of bones

• Bones grow in two directions

  • length

  • width

• Interstitial in growth plate

• Appositional in perichondrium

Epiphyseal Plate zone cartilages

Cartilage Growth Plate

Appositional Bone Growth

• Osteoblasts build bone at the circumferential lamellae

• Osteoclasts widen the medullary cavity

Osteopenia

• a condition where bone mineral density is lower than normal, sitting in the warning stage between healthy bone and osteoporosis. [1, 2]