Chapter 4 Review

tissues

a group of identical cells found together in the body, have a common embryonic origin

histology

microscopic study of tissue appearance, organization and function

4 types of tissue

epithelial, connective, muscle, nervous

epithelial tissue

can be covering and lining surface of the body or glandular and in secretory tissues

function of epithelial tissue

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

4 characteristics of all epithelial tissue

polarity (organelles distributed across cell), supported by connective tissue and separated by basal lamina, completely avascular, and capable of regenerating

tight junction

similar to nailing cells together, no space in between them and no exchange of materials allowed, helps to act as a selective barrier

desmosome

combination of tight and gap junctions, strong yet flexible so often found in muscle cells

gap junction

allows material exchange between membranes of adjacent cells, facilitate fluid and ion movement (weakest junction)

simple squamous epithelial

flat and thin, found in the lungs because they allow the easy exchange and diffuse of gases (one layer)

simple cuboidal

box-like with a circular nuclei, found in sweat glands/ other ducts and are active in secretion (one layer)

simple columnar

elongated, nucleus in the basal end, found in the small intestines to absorb nutrients (have cilia on the apical end to assist in movement of molecules) (one layer)

stratified squamous

multi layers of thin cells, protect from wear and tear MOST COMMON STRATIFIED TYPE, found on the skin and tongue

stratified cuboidal and columnar

several layers, in certain glands and ducts but not common in the human body

pseudo-stratified columnar

appear stratified but is really just one layer of irregular columnar cells (nuclei are at different levels within the cell) found in trachea and urinary system and have cilia

transitional epithelium

have gradual shape changes as the bladder fills with liquid (cells transition from cuboidal to squamous as it fills)

glandular epithelia

can be endocrine or exocrine to release secretions from the inside of a cell

endocrine gland

ductless, release secretions directly into surrounding tissues and fluids (HORMONES)

exocrine gland

secretions (sweat, saliva, milk) leave through ducts that opens into the external environment (ex. secretions into the lumen of the GI tract)

connective tissue components

1. cells

2. large amounts of amorphous ground substance (matrix)

3. protein fibers

function of connective tissue

support and connect other tissues and provide protection (adipose cells store energy as fat for insulation)

fibroblasts

most abundant cells in connective tissue, responsible for extra-cellular matrix

adipocytes

store lipids that fill the cytoplasm (found in hypodermis)

mesenchymal cells

multi-potent adult stem cells that can differentiate into any type of connective tissue cells needed for healing and damaged tissue

3 main fibers secreted by fibroblasts

collagen, elastic, reticular

collagen fiber

flexible with great strength, resist stretching and give ligaments and tendons their resilience and strength

elastic fiber

contains a protein elastic that returns to its original shape after being stretched or compressed (prominent in the skin and vertebral columns)

reticular fiber

formed from the same subunits as collagen but these are narrow and in a branching network, most abundant in soft organs like the liver and the spleen

types of loose connective tissue

aerolar, adipose, reticular

areolar connective tissue

little specialization, web like fashion and fills the space between muscle fibers; underlies most epithelia

adipose connective tissue

fat storage cells, little extracellular matrix

reticular connective tissue

mesh like supportive framework for soft organs, produce reticular fibers that form a network for other cells to attach to

types of dense connective tissue

regular, irregular, elastic

regular dense tissue

tissues are parallel to resist stretching (compose ligaments and tendons)

irregular dense tissue

direction of fibers is random so there is greater strength in all directions and less in just one, found in the dermis and joint capsules

elastic dense tissue

made of elastin and collagen fibers, can return to the original length after stretching (on the walls of the aorta)

types of cartilage

hyaline, elastic, fibro

hyaline cartilage

most common, short dispersed collagen fibers with lots of proteoglycans, very strong and protective (found in ribcage and on bones)

elastic cartilage

contains elastic fibers and collagen and proteoglycans, gives rigid support and elasticity like in the outer ear

fibrocartilage

tough due to thick bundles of collagen fibers in the matrix, found in the knee joint and intervertebral disks

bone

hardest connective tissue, good for protection and support

blood and lymph

fluid connective tissue, transport nutrients salts and wastes; lymph drains into blood vessels delivering molecules (could not enter the bloodstream otherwise)

muscle tissue

have properties that allow movement, is excitable (responds to a stimulus) and contractile (shortens to generate a pulling force)

skeletal muscle tissue

attaches to bones, contraction makes voluntary movements; are striated with many nuclei

cardiac muscle tissue

form the wall of the heart, create involuntary movement and contain specialized cell junctions (intercalated discs)

smooth muscle tissue

involuntary movements of internal organs (in digestive, urinary, reproductive systems as well as airways and arteries) (spindle shaped cells with no visible striations)

nervous tissue

excitable and capable to sending and receiving signals that provide information to the body

cutaneous membrane

skin; stratified squamous resting on connective tissue (apical surface exposed) covered with dead keratinized cells

mucous membrane

made of connective and epithelial tissues; line body cavities and hollow passages

serous membrane

epithelial membrane composed of epithelial cells supported by connective tissue (line cavities that do not open to the outside and covers the organs in those cavities)