CH 4 Tissues
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CH 4 Tissues
CH 4 Tissues
What are the 4 types of Tissue?
What are tissues?
building blocks of the body's organs
What is Epithelium?
means covering and is a sheet of cells that covers a body surface or lines a body cavity
What are the characteristics of epithelia?
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
When an Epithelia layer is known as simple, what kind of layer is it?
just one cell layer
When an Epithelia layer is known as stratified, what kind of layer is it?
more than one layer
When an Epithelia layer is known as squamous, what kind of layer is it?
platelike flat cells
When an Epithelia layer is known as cuboidal, what kind of layer is it?
shaped like cubes
When an Epithelia layer is known as is columnar, what kind of layer is it?
cells are taller than they are wide
What is simple squamous epithelium?
- 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
What is Simple Cuboidal Epithelium?
- 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
What is Simple Columnar Epithelium?
- 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
What is Pseudostratified Columnar Epithelium?
- 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
What does Stratified Squamous mean?
contain two or more layers of cells
What is Stratified Squamous Epithelium?
- 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
What is Stratified Cuboidal & Columnar Epithelia?
rare type of tissue that forms only large ducts of glands
What is transitional epithelium?
- 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
What are Endocrine glands?
- internal secretion
- lacks ducts
- produce messenger molecules called hormones
What are exocrine glands?
- has ducts
- secrete their products onto body surfaces (skin) or into body cavities
What are the 4 basic functions of connective tissue?
-support & bind other tissues
-hold body fluids
-defends the body against infection
What are the 4 main classes of connective tissue?
connective tissue proper, cartilage, bone tissue, blood
What are the characteristics of connective tissues?
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
What is connective tissue proper?
*functions as a binding tissue & resists mechanical stress, particularly tension
*has loose connective tissue (areolar, adipose, reticular) & dense connective tissue (regular, irregular, elastic)
What is cartilage?
- resists compression
- functions to cushion & support body structures
: hyaline, elastic, & fibrocartilage
What is bone tissue?
- hard tissue that resists both compression & tension
- functions in support
: compact & spongy bone
What is blood?
- a fluid tissue
- functions to carry oxygen, carbon dioxide, nutrients, wastes, & other substances (hormones, for example)
What is loose connective tissue of connective tissue proper?
contains areolar, adipose, & reticular connective tissue
- fibers are distributed throughout the tissue, but are seperated from each other by ground substance
What is areolar connective tissue?
- 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
What are the 3 fibers in areolar tissue?
collagen fibers - strongest/withstand pulling
reticular fibers - forming a network for support
elastic fibers - allow tissues to reshape when stretched
What is adipose tissue?
- crowded with fat cells
- richly vascularized, reflecting its high metabolic activity
- occurs in layer beneath skin called hypodermis
What is reticular connective tissue?
retcular fibers form a broad, 3D network like the frame of a house
What is dense connective tissue?
- contains more collagen than areolar connective tissue
- has thick collagen fibers that can resist extremely strong pulling forces
What is dense irregular connective tissue?
- 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
What is dense regular connective tissue?
- 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
What is cartilage?
- 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
What is bone?
- support & protect body structures
- contains inorganic calcium salts (bone salts)
What is blood?
functions as the transport vehicle for the cardiovascular system, carrying defense cells, nutrients, wastes, respiratory gases, & many other substances throughout the body
What does nervous tissue contain?
neurons - send an impulse to activate a cell & control body function
glial - form supportive structures, insulate, & nourish neurons
What is mucous membrane?
- 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
What is cutaneous membrane?
- the skin, covering the outer surface of the body
- dry membrane
What is serous membrane?
- slippery membranes that line the closed pleural, pericardial, & peritoneal cavities
Compare and contrast mucous, serous, & cutaneous membranes
Serous - slippery
Mucous -wet or moist
What is skeletal muscle tissue?
pull on bone to cause body movement and is striated, voluntary
What is cardiac muscle tissue?
contracts to propel blood through blood vessels, striated, involuntary
What are smooth muscle tissues?
no visible striations inn its cell, acts to squeeze substances through these organs by alternately contracting & relaxing
Explain the stages of tissue response to injury
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