Anatomy and Physiology Tissues and Integumentary

help meeeeeeeee

Epithelial, muscle, nervous, connective

Basic tissue types

Epithelium

a sheet of cells that covers surfaces or cavities

Functions of epithelium

include protection, absorption, filtration, excretion, secretion, and sensation.

Apical surface

upper free side of epithelim

Basal surface

lower attached side of epithelium

Basement membrane, basal lamina, reticular lamina

Connective tissues supporting epithelium

Tight junctions and desmosomes

specialized contacts of epithelium

Blood vessels

Epithelium has no

Highly regenerative and polar

Epithelium is…

simple squamous

a single layer of flat cells that facilitates diffusion and filtration.

simple cuboidal

a single layer of cube-shaped cells that functions in secretion and absorption. most often found in glands and kidneys

simple columnar

a single layer of column-shaped cells that is involved in absorption and secretion, often found in the digestive tract. Often with microvilli

stratified squamous

a type of epithelial tissue consisting of multiple layers of flat cells, providing protection against friction and abrasion. It is commonly found in areas subject to wear, such as the skin, mouth, and esophagus.

stratified cuboidal

a type of epithelial tissue made up of multiple layers of cube-shaped cells. It is rare but typically found in large ducts of sweat glands, mammary glands, and salivary glands.

stratified columnar

a type of epithelial tissue composed of multiple layers of column-shaped cells, providing protection and found in some glands and the male urethra.

pseudostratified columnar

a type of epithelial tissue that appears to have multiple layers due to differing cell heights but is actually a single layer. It is typically ciliated and found lining the respiratory tract.

transitional epithelia

Basal layer looks cuboidal or columnar but apical varies. This tissue that can stretch and change shape, typically found in the bladder and ureters, allowing for expansion as they fill with urine.

glands

classified by site of release and number of cells

endocrine glands

structurally diverse ductless glands that secrete hormones by exocytosis

exocrine glands

secretions released via ducts

unicellular exocrine

goblet cells and mucous cells

multicellular exocrine

composed of duct and secretory unit

Three common characteristics of connective tissue

• common embryonic origin

• variable vascularization

• cells embedded in extracellular matrix

Functions of connective tissue

• binding and support

• protection

• insulation

• fuel storage

• substance transport

Components of connective tissue

• ground substance

• fibers

• cells

Ground substance

Unstructured gel-like material that fills space

Fibers

collagen, elastic, reticular

Blast cells

secrete ground substance and fibers

Cyte cells

make up and maintain matrix

Classes of connective tissue

connective tissue proper, cartilage, bone, blood

Areolar connective tissue

• Loose arrangement of fibers & increased ground substance

• Supports and binds other tissues

• Widely distributed, found most often under epithelia (lamina propria!)

Adipose tissue

• Sparse matrix with closely packed adipocytes; richly vascularized

• Acts in shock absorption, insulation, energy storage, thermogenesis

• Found most often in subcutaneous area, abdomen, hips

Reticular connective tissue

• Matrix is solely reticular fibers

• Forms stroma (framework) to support other cells

• Most common in lymphoid organs

Dense regular

• Closely packed bundles of collagen fibers produce high tensile strength

• Withstands high tension & stretching but poorly vascularized

• Commonly found in tendons & ligaments

Dense irregular

• Thick bundles of collagen run in all directions

• Forms sheets that resist tension in multiple directions

• Found in skin, joint capsules, & organ coverings

Dense elastic

• Very similar to dense regular but with high proportion of elastic fibers

• Aids in tissue recoil after stretching

• Found in some ligaments, large arteries, and lungs

Characteristics of cartilage

high levels of collagen and proteoglycans, avascular, lacking nerve fibers

Hyaline cartilage

most abundant form of cartilage, found on ends of long bones and respiratory passages

Elastic cartilage

more elastic fibers, more stretchy, found in external ear and epiglottis

Fibrocartilage

chondrocytes and collagen fibers, found in intervertebral discs and knee joint

Bone

supports and protects body, stores fat, synthesizes blood

Osteons

individual structural bone unit

Blood

atypical connective tissue, consists of cells surrounded by plasma, functions in transport and carrying nutrients, waste, gases

Skeletal muscle

moves skeleton, striated, multiple nuclei, voluntary control

Cardiac muscle

moves heart, striated, one nucleus, involuntary control

Smooth muscle

Un-striated, one nucleus, involuntary control

Nervous tissue

regulates and controls body’s functions via brain, spinal cord, and nerves

Cutaneous membrane

Skin

Mucous membrane

lines cavities open to exterior, epithelia lies over lamina propia

Serous membrane

found in closed ventral cavities. Parietal lines walls and visceral lines organs. Simple squamous epithelium over areolar connective tissue

Steps of tissue repair

inflammation, organization, regeneration

Inflammation

Blood vessels become leaky, WBC enter area to form clot, clot forms scab

Organization

clot replaces by granulation tissue, collagen fibers form and encourage cell growth, surface epithelium begins regeneration

Regeneration

fibrotic area contracts to pull edges together, epithelium thickens, scar tissue underlies regenerated tissue

High regenerative capactiy

epithelia, bone, some connective tissue

Moderate regenerative capactiy

smooth muscle and dense regular connective tissue

low/no regenerative capacity

cardiac muscle and nervous tissue

How does scar tissue impair organ function

impedes movement, impairs nerves, decreases capacity, adheres to other surfaces

Epithelia with age

thins, less efficient repair, atrophy, mutation in DNA

To view tissue under a microscope

fixed, sectioned, and stained

Dense irregular

primary tissue of the dermis

extracellular matrix

Nonliving material located between the cells of a connective tissue

reticular tissue

comprises bone marrow; spleen; lymph nodes

Parietal pleura

Which serous membrane lines the thoracic wall where the lungs are housed?

Make up the integumentary system

skin, hair, nails, sweat glands, sebaceous glands

functions of the integumentary system

barrier, temperature regulation, sensation, metabolism, blood reservoir, excretion

regions of the skin

dermis and epidermis

epidermis

superficial, avascular epithelia

dermis

deep, fibrous connective tissue, vascular

cells in the epidermis

keratinocytes, melanocytes, dendritic cells, tactile cells

keratinocytes

primary cells of epidermis, connected by desmosomes

melanocytes

located deep in epidermis. Melanin is packaged into melanosomes & given to keratinocytes to protect against UV

dendritic cells

macrophages that patrol deep layers and activate immune system

tactile cells

sensory receptors

Layers of the epidermis

basale, spinosum, granulosum, lucidum, corneum

Stratum basale

• Attached to dermis

• Single row of stem cells produces two daughter cells (one stays, one moves up)

Stratum spinosum

• Several layers of keratinocytes containing prekeratin filaments

Stratum granulosum

• Cells begin to flatten & lose nuclei & organelles

• Keratinization begins

Stratum lucidum

• Only found in thick skin

• Thin translucent band of dead keratinocytes

Stratum corneum

• 20-30 rows of flat, anucleated, keratinized dead cells

• Majority of epidermal thickness

dermis layers

papillary and reticular

Papillary layer

•Areolar connective tissue with of loose, interlacing collagen and elastic fibers and blood vessels

•Dermal papillae: fingerlike projections indent the epidermis

•Causes friction ridges (fingerprints!)

Reticular layer

•About 80% dermal thickness

•Coarse, dense fibrous connective tissue with many elastic & collagen fibers

• Nourished by cutaneous plexus

•Collagen most often run in bundles parallel to surface (gaps = cleavage lines)

• Flexure lines: dermal folds at/near joints (accommodates movement)

Skin pigments

melanin, carotene, hemoglobin

Melanin

melanocytes in two different forms (reddish yellow and brownish black)

carotene

• accumulates from diet

• yellow orange pigment accumulates in stratum corneum and hypodermis

• converted to vitamin A for epidermal health

hemoglobin

• present in red blood cells

• low levels of melanin allow reddish hue from hemoglobin to show

Alterations of skin color can indicate…

disease

Hair

Flexible strands of dead keratinized cells that grow out of the epidermis (almost everywhere)

keratinization is complete

Shaft is exposed above the skin’s surface when…

medulla

central core of hair

cortex

layers of flattened cells in hair

cuticle

outermost layer of hard keratinized cells in hair

Hair bulb

termination of root deep in follicle

Hair matrix

mitotically active basal cells from which hair grows

Hair papilla

capillaries & nerve endings (and melanocytes)

epithelial root sheath

surrounds the hair

glassy membrane

connective tissue sheath that covers the root and connects it to the dermis

Arrector pili

smooth muscle that cause hair to “stand up”

functions of hair

protection, sensory input, temperature regulation