Anatomy Exam 2

BIOL 344

histology

the study of tissue

tissue

a group of cells similar in structure and function

what are the 4 basic tissue types

epithelial, connective, muscle, nervous

biopsy

examination of tissue removed from a living body

epithelial tissue

a sheet of cells that covers body surfaces or cavities

covering and lining epithelia

on external and internal surfaces (ex. skin)

glandular epithelia

secretory tissue in glands (ex. salivary glands)

what are the main functions of epithelial tissue?

protection, absorption, filtration, excretion, secretion, sensory reception

what are the 5 distinguishing features of epithelial tissue

1. polarity

2. specialized contacts

3. supported by connective tissues

4. avascular, but innervated

5. regeneration

simple squamous epithelia location and functions

diffusion, filtration, secretion

• important where gas exchange occurs

Simple squamous epithelium

simple cuboidal location and functions

secretion, absorption

• forms walls in the ducts of glands and the kidney tubules

simple cuboidal

simple columnar location and function

absorption and secretion

• found primarily in the digestive tract, gallbladder, and bronchi

  • some have microvilli and some have cilia

simple columnar epithelium

pseudostratified columnar epithelia location and function

secretion, particularly of mucus; as well as movement of mucus via cilia

• located mostly in the upper respiratory tract

pseudostratified columnar

stratified squamous epithelia location and function

mainly used for protection

• found on the skin and mucus membranes

stratified squamous

transitional epithelia location and function

found in the bladder

cells have the ability to change shape to optimize flow of urine

gland

one or more cells that make and secrete an aqueous solution called a secretione

exocrine

externally secreting

endocrine

internally secreting

merocrine (eccrine)

most secrete products through exocytosis (sweat, pancreas)

holocrine

accumulate products within, then rupture (sebaceous oil glands)

apocrine

accumulate products within, but only apex ruptures (armpit, perineal, genitalia)

connective tissue functions

binding and support, protection, insulation, storing energy, and transportation

what are the 3 main elements of connective tissue

ground substance, fibers, cells

ground substance

• gel-like material that fills space between cells

• contains interstitial fluid and proteoglycans

  • chondroitin sulfate and hyaluronic acid

fibers

1. collagen; strong and abundant

2. elastic; allow for stretch and recoil

   1. reticular; unique highly branched collagenous fibers

“blast” cells

create ECM

“cyte” cells

mature, less active, but maintain matrix

Areolar CT

• upper half of the dermis

  • packing material between other tissues

  • loose fibers allow for increased ground substance

loose and fibrous

areolar CT

adipose CT

• white fat

  • functions in shock absorption, insulation and energy storage

loose and fibrous

adipose CT

reticular CT

• reticular fibers form a mesh like stroma; acts as support for blood cells in lymph nodes, spleen and bone marrow

loose and fibrous

reticular CT

dense regular CT

• Very high tensile strength; can withstand high tension and stretching
  • Closely packed bundles of thick collagen fibers run parallel to direction of pull
  • Poorly vascularized!!!!

• example: tendons and ligaments

dense regular CT

dense irregular

Same elements as dense regular, but bundles of collagen are thicker and irregularly
arranged

• resists tension from many directions

• example: bottom half of dermis, joint capsules

dense irregular CT

dense elastic CT

• very elastic

  • found as ligaments connecting vertebrae, walls of arteries

Dense elastic CT

Cartilage

tough yet flexible material that lacks nerve fibers

• Avascular

Hyaline cartilage

• most abundant

  • found at tips of long bones, nose, trachea, larynx, and cartilage of the ribs

Elastic cartilage

• contains more elastic fibers

  • found in ears and epiglottis

Fibrocartilage

Strong, found in areas such as invertebral discs and meniscus of knee

Bone connective tissue

• Supports and protects body structures
  • Stores fat and synthesizes blood cells in cavities
  • Has more collagen compared to cartilage
  • Has inorganic calcium salts

• richly vascularized

where are blood cells made?

in the bone marrow

Blood connective tissue

• Most atypical connective tissue because it is
  fluid
  • Consists of cells surrounded by matrix (plasma)
  • Functions in transport and in carrying
  nutrients, wastes, gases, and other
  substance

erythrocytes

red blood cells

leukocytes

white blood cells

thrombocytes

platelets, clots the blood

Skeletal Muscle tissue

• voluntary

• attached to bones via tendons

• contain striations

Cardiac Muscle Tissue

• involuntary

• heart muscle

• contains branched muscle fibers

Smooth muscle tissue

• involuntary

• no striations

• GI, Blood vessels, Airways

nervous tissue

Main component of nervous system (brain,spinal cord, nerves)
• Regulates and controls body functions

Neurons

specialized nerve cells that generate and conduct nerve impulses

Glial cells

Supporting cells that support, insulate, and protect neurons

Regeneration in tissues

same kind of tissue replaces destroyed tissue, so original function is restored

Fibrosis in tissues

connective tissue replaces destroyed tissue, and original function lost (scar tissue)

what tissues regenerate great?

Epithelial, bone, areolar CT, dense irregular CT

What tissue regenerates okay?

Smooth muscle and dense regular CT

What tissues have poor regenerative capabilities?

Cardiac muscle and nervous tissue of brain and spinal cord

4 steps in tissue repair

hemostasis (blood clot), inflammation, proliferation (growth of new tissue), remodeling

why is scar tissue important? (bad)

Scar tissue that forms in organs, particularly the heart,can severely impair the function of that organ

Integumentary System

hair, skin, glands, and nails

epidermis

superficial region of the skin

• contains epithelial tissue and is avascular

dermis

• underlies the epidermis

• areolar and dense irregular connective tissue

• contains nerves, blood cells, hair follicles, and oil/sweat glands

• strong and flexible

hypodermis

subcutaneous layer deep to skin

• mostly adipose tissue that absorbs shock and insulates

• not a true layer of the skin

keratinocytes

• produce fibrous keratin (protection)

  • millions slough off everyday

melanocytes

• located in deep epidermis

• produce pigment melanin (UV protection)

Dendritic cells

specialized macrophages that act as antigen presenting cells (immune cells that clean your skin from infection)

Merkel Cells

Sensory neurons that sense light touch

What are the 5 layers of the epidermis?

1. stratum basale (deepest)

2. stratum spinosum

3. stratum granulosum

4. stratum lucidum (only in THICK skin) (hands, feet, elbows, and knees)

5. stratum corneum (most superficial)

stratum basale

deepest skin layer, attached to dermis. single row of stem cells that actively divide (highly mitotic).

stratum spinosum

several skin layers thick; appear spikey. these cells contain weblike system of pre-keratin filiments that allow resist tension and pulling.

stratum granulosum

• 4-6 layers thick

• karatinazation begins here

• cells above this layer die

stratum lucidum

• found only in thick skin

• Consists of thin, translucent band of two to three rows of clear, flat, dead keratinocytes

stratum corneum

• 20–30 rows of flat, keratinized dead cells

• cells function to protect deeper cells from the environment and prevent water loss

papillary dermis

upper layer of dermis

• made of lose areolar connective tissue

  • contain collagen and elastic fibers, fibroblasts and blood vessels

dermal papillae

fingerlike projections protruding into epidermis

reticular dermis

• 80% of dermal thickness

• dense fibrous connective tissue

  • have stretchy properties as well as strength and resilience properties

melanin

only pigment made in the skin, protect keratinocyte DNA from UV damage

carotene

Yellow to orange pigment, most obvious in palms and soles. Can be converted to vitamin A.

Hemoglobin

Pinkish hue of fair skin is due to lower levels of melanin. Skin of caucasians is more transparent, so color of hemoglobin shines through.

Cyanosis

blue skin color; low oxygenation of hemoglobin

pallor (blanching or pale)

Anemia, low blood pressure, fear, anger

erythema (redness)

fever, hypertension, inflammation, allergy

jaundice (yellow)

liver disorders, build up of bilirubin in tissues

hair

dead keratinized cells

• warn of insects on skin

• hair on head protects of trauma

• protect from heat loss

• shield of skin from sunlight

Two regions of hair

1. shaft; above scalp

2. root; within scalp

3 parts of hair shaft

1. medulla; central core

2. cortex; several layers of cells surrounding medulla

3. cuticle; outer layer consisting of many cell layers

hair bulb

expanded area at deep end of follicle

• contains hair matrix; actively dividing cells

hair follicle receptor

sensory nerve endings that wrap around bulb, make the hair a sensory touch receptor

arrector pili

smooth muscle attached to follicle, responsible for goosebumps

lanugo

soft, unpigmented hair found on fetus/newborn

vellus hair

pale, fine body hair found on children and adult females

terminal hair

found on scalp and eyebrows

after puberty; can also be found in axillary and pubic regions