CH 4 Tissues

• Epithelium: COVERING
• Connective Tissue: SUPPORT
• Muscle Tissue: MOVEMENT
• Nervous Tissue: CONTROL

building blocks of the body's organs

means covering and is a sheet of cells that covers a body surface or lines a body cavity

• 1. cellularity - composed almost entirely of cells
• 2. specialized contacts - cells are directly joined at many points by special cell junctions
• 3. polarity - all epithelia have an apical (upper) and a basal (lower) surface
• 4. support by connective tissue - supported by an underlying layer of connective tissue
• 5. avascular but innervated - lacks blood vessels, but has nerve endings
• 6. regeneration - high regenerative capacity

just one cell layer

more than one layer

platelike flat cells

shaped like cubes

cells are taller than they are wide

• - single layer of flat cells that occurs wherever small molecules pass through a membrane quickly, by processes of diffusion or filtration
• - can be found in the lungs and forms the thin walls of the air sacs, where gas exchange occurs
• - makes exchange of materials quick & easy

• - a single layer of cube-shaped cells
• - forms secretory cells of many glands, walls of smallest ducts of glands, & of many tubules in the kidney
• - forms gland ducts & tubules

• - single layer of tall cells aligned like soldiers in a row
• - lines digestive tube from stomach to anal canal
• - functions in active movement of molecules, namely in absorption, secretion, & ion transport
• - layer of tall cells that line the digestive tract

• - varied in height
• - all of its cells rest on basement membrane
• - only the tall cells reach the apical surface of epithelium
• - short cells are undifferentiated & continuously give rise to the tall cells
• - functions in secretion or absorption

contain two or more layers of cells

• - has many cell layers whose surface cells are squamous
• - thickest & best adapted for protection
• - covers the often-abraded surfaces of our body
• - forms outermost layer of skin & extends a certain distance into every body opening that is directly continuous with the skin
• - epidermis of the skin is keratinized

rare type of tissue that forms only large ducts of glands

• - lines the inside of the hollow urinary organs
• - undergoes "transitions" in shape
• - forms an impermeable barrier that keeps urine from passing through the wall of the bladder

• - internal secretion
• - lacks ducts
• - produce messenger molecules called hormones

• - has ducts
• - secrete their products onto body surfaces (skin) or into body cavities

• -support & bind other tissues
• -hold body fluids
• -defends the body against infection
• -store nutrients

connective tissue proper, cartilage, bone tissue, blood

• 1. relatively few cells, lots of extracellular matrix - seperated from one another by a large amount of extracellular material
• 2. extracellular matrix composed of ground substance & fibers - produced by cells of connective tissue
• 3. embryonic origin - all originate from the embyonic tissue called mesenchyme

• *functions as a binding tissue & resists mechanical stress, particularly tension
• *has loose connective tissue (areolar, adipose, reticular) & dense connective tissue (regular, irregular, elastic)

• - resists compression
• - functions to cushion & support body structures
• - subclasses: hyaline, elastic, & fibrocartilage

• - hard tissue that resists both compression & tension
• - functions in support
• - subclasses: compact & spongy bone

• - a fluid tissue
• - functions to carry oxygen, carbon dioxide, nutrients, wastes, & other substances (hormones, for example)

• contains areolar, adipose, & reticular connective tissue
• - fibers are distributed throughout the tissue, but are seperated from each other by ground substance

• - underlies almost all the epithelia of the body
• - surrounds almost all the small nerves & blood vessels including capillaries
• - supporting & binding other tissues
• - holding body fluids
• - defending the body against infection
• - storing nutrients as fat

• collagen fibers - strongest/withstand pulling
• reticular fibers - forming a network for support
• elastic fibers - allow tissues to reshape when stretched

• - crowded with fat cells
• - richly vascularized, reflecting its high metabolic activity
• - occurs in layer beneath skin called hypodermis

retcular fibers form a broad, 3D network like the frame of a house

• - contains more collagen than areolar connective tissue
• - has thick collagen fibers that can resist extremely strong pulling forces

• - thicker collagen fibers
• - fibers run in different planes
• - resist strong tensions from different directions
• - dominates the leathery dermis of the skin
• - makes up the fibrous capsules that surround certain organs in the body

• - all collagen fibers usually run in the same direction
• - crowded between collagen fibers are rows of fibroblasts
• - poorly vascularized
• - contains no fat cells or defense cells
• - is the main component of ligaments & tendons
• - also forms fascia

• - a firm but flexible tissue
• - occurs in several parts of the skeleton
• - consists of cells seperated by an abundant extracellular matrix
• - contains no blood vessels or nerves

• - support & protect body structures
• - contains inorganic calcium salts (bone salts)

functions as the transport vehicle for the cardiovascular system, carrying defense cells, nutrients, wastes, respiratory gases, & many other substances throughout the body

• neurons - send an impulse to activate a cell & control body function
• glial - form supportive structures, insulate, & nourish neurons

• - lines inside of every hollow internal organ that opens to the outside of the body (tubes of the respiratory, digestive, reproductive, & urinary systems)
• - all mucous are wet or moist

• - the skin, covering the outer surface of the body
• - dry membrane

- slippery membranes that line the closed pleural, pericardial, & peritoneal cavities

• Serous - slippery
• Cutaneous -dry
• Mucous -wet or moist

pull on bone to cause body movement and is striated, voluntary

contracts to propel blood through blood vessels, striated, involuntary

no visible striations inn its cell, acts to squeeze substances through these organs by alternately contracting & relaxing

• inflammation - extess blood flow causes area to become red & hot, then swells & pts pressure on pain receptors
• immune response - fight infection
• repair - after scab forms, healing tissues may replace themselves or cause a scar