Download Chapter 5 Tissue Notes File

Chapter 5 Notes – Tissues
Tissue: a group of similar cells sharing a
common origin that are united to perform a
particular function
-includes extracellular fluid and intercellular
materials (products that exist between cells)
-4 major types
• epithelial
• connective
• muscle
• nerve
Epithelial Tissue (epithelium): consists of cells
that are very closely packed together w/ little
or no intercellular materials
-avascular – tissue w/o blood vessels
-function is to cover body surfaces, line
inside of body cavities/organs, form glands,
secrete and absorb substances, protect
Covering and Lining Epithelium
-covers body surfaces and lines walls of body
cavities/openings
-cells are stationary – anchored to the surface
by a thin layer of intercellular material called
the basement membrane (connects epithelium
to an underlying region of connective tissue)
-free surface – open to body cavities/organs or
external environment; (lumen – hollow area)
 3 Shapes
1) squamous – flat
2) cuboidal – cube-shaped
3) columnar – cylindrical or elongated
(rectangular)
 2 Cell arrangements
1) simple – single cell layer
2) stratified – multiple cell layers
** Simple Squamous Epithelium – consists of a
single layer of flattened cells
- all cells touch a basement membrane and
a free surface
- cells have a centrally located nucleus
- very tightly packed together
- allows for efficient diffusion of materials
-found inside walls of blood and lymphatic
vessels
-forms walls of capillaries, air sacs in lungs,
linings of body cavities
** Simple Cuboidal Epithelium – consists of a
single layer of cube-shaped cells
-centrally located nucleus
-often contain cilia or microvilli along free
surface
-forms walls of small tubes (ducts) that carry
secretions from one place to another
-found in kidneys, liver, ovaries, and many
glands
** Simple Columnar Epithelium – single layer
of cylindrical cells
-nuclei found near basement membrane
-cells frequently secrete a product (lots of
rough endoplasmic reticula + golgi bodies)
-many goblet cells (secrete mucus)
-found in uterus, stomach, small intestines
** Stratified Squamous Epithelium – many
layers, surface layer is squamous; deepest
layers contain cuboidal/columnar cells
-forms outer layer of skin and dips in all body
openings (protection)
-lines oral cavity, esophagus, vagina, and anal
canal
**Stratified Cuboidal Epithelium – two or three
layers of cuboidal cells surrounding a lumen;
-line ducts in mammary glands, sweat glands,
salivary glands, and pancreas
**Stratified Columnar Epithelium – several
layers of cells (cuboidal cells near basement
membrane, columnar cells near free surface)
-found in male reproductive tract and parts of
the pharynx
** Pseudostratified Columnar Epithelium –
appears multilayered, but is NOT
-different shaped cells and locations of nuclei
-each cell touches the basement membrane,
but not all touch free surface
-lines part of the respiratory tract (trachea,
bronchi)
-some cells contain long cilia that create
currents to move mucous (pseudostratified
ciliated columnar epithelium)
** Transitional Epithelium – multilayered
arrangement of cubelike/irregular shaped cells
-elasticity – ability to stretch
-extensibility – ability to return to original
shape
-lines urinary bladder and ureters, urethra
Glandular Epithelium
- consists of closely packed cells that are highly
specialized to manufacture and secrete
products
**Exocrine gland – empties products into ducts
-ducts transport product onto body surface or
into a cavity
-sweat/oil glands in skin, salivary glands, singlecelled mucous glands
** Endocrine glands – secrete products into
extracellular space, where they move into the
bloodstream
-bloodstream transports products throughout
body
-pituitary gland, thyroid gland, adrenal gland,
etc. (hormones)
Connective Tissue – composed of widely
scattered cells that lie w/in a large amount of
nonliving intercellular material
Function: supports/protects body parts;
manufactures blood cells; holds tissues/organs
in place
-Cells are 2 types
1) Macrophages – wandering cells
Function: protects tissue from infection
2) Fibroblasts – fixed (stationary) cells
Function: produces and maintains intercellular fluid (mixture of ground substance
(sugar-protein molecules and interstitial fluid)
and several types of protein fibers);
-3 types of fibers present in intercellular fluid
1) Collagenous fibers – most abundant, thick,
wavelike strands made of collagen - flexible
protein that is tensile (resists stretching)
-found in tendons (connect muscle to
bone), ligaments (connect bone to bone),
and organs that remain stationary in body;
forms scar tissue
2) Elastic fibers – composed of elastin (protein
that has elasticity + extensibility)
3) Reticular fibers – composed of reticulin
(thin, branching protein that resists physical
stress); not abundant
Connective tissue is vascular – blood vessels
pass though intercellular material (allows tissue
to grow and repair)
-4 major types of connective tissue
1) connective tissue proper
2) cartilage
3) bone
4) blood-forming tissue
Connective Tissue Proper
-fibroblast – cells that produce intercellular
material
*3 general groups (differ in amounts + types of
fibers present in the matrix)
1) Loose Connective Tissue (Areolar) – most
widespread; forms many membranes in body
-all 3 types of protein fibers are found in a
loose, disorganized network surrounded by
a fluid ground substance: small # of cells
interspersed - mostly fibroblasts and
macrophages (phagocytic white blood cells)
-provides a structural anchor to body parts
b/c of many fibers
-found between skin and muscle, on
surfaces of organs, filling in spaces between
organs
2) Adipose Tissue – composed mostly of
fibroblasts called adipocytes – large spherical
cells containing a deposit of fat
- little intercellular material surrounding
adipose cells w/ many reticular fibers
- stores energy as fat; insulates organs/
provides a shock-absorbing cushion
- fat stored in adipose cells – triglycerides
3) Dense Connective Tissue – tightly packed
protein fibers w/ little space for other
substances including cells
-abundant collagen fibers
2 types
*Dense irregular connective tissue
- non-parallel protein fibers that branch
- randomly distributed fibroblasts
-forms dermis (deep skin layers); wraps
around bones and cartilage
*Dense regular connective tissue
- parallel protein fibers
-linear fibroblasts
-forms tendons and ligaments
Cartilage – contains a very dense and firm
intercellular material (matrix) that is composed
of many protein fibers w/in a thickened, gel-like
ground substance
-harder/more solid than connective tissue
proper
-provides support, frameworks, and
attachments; forms models for developing
bones
• chondrocyte – cartilage cells that maintain
the matrix
• lacunae – spaces where chondrocytes are
found
• perichondrium – vascular layer of dense
connective tissue surrounding cartilage;
nourishes chondrocytes
* 3 types of cartilage
1) Hyaline
– most abundant
- bluish-white (must be dyed to see it)
- composed of collagen
- located in the upper portion of the respiratory
tract; at the ends of bones where it forms
movable joints; at the ends of ribs
- forms skeleton of fetus
2) Elastic
-yellowish
-composed of elastic fibers
-firm, but flexible
-located in ears, ends of nose, small lid over
opening to larynx (epiglottis)
3) Fibrocartilage – consists of a solid, but
flexible matrix w/ collagen fibers
-found in joints like knees and pelvis,
intervertebral discs
Bone – intercellular material is filled w/ mineral
salts and collagenous fibers, making it the
hardest/most durable tissue
•matrix – intercellular material of bone
•osteocytes – bone cells (contained in lacunae)
which maintain the matrix of bone
•lamellae – layers of bone that form around
Haversian canals (where blood vessels are
found)
•periosteum – membrane surrounding bone
where blood vessels penetrate and nourish
osteocytes
•canaliculi – tiny channels that extend outward
from bone cells (connect cells)
* compact bone – matrix is densely packed w/
deposits of mineral salts and collagen
* spongy bone – matrix is not as dense; filled
w/ blood-forming tissue called red marrow
Blood-Forming Tissue and Blood
Blood-forming tissue – manufactures cellular
components of blood
3 components
1) stem cells that produce blood cells
2) newly formed maturing blood cells
3) small amount of protein
-softest connective tissue b/c it lacks collagen
and mineral salts
2 types of blood-forming tissue
* red marrow – found in cavities w/in spongy
bone (hematopoietic tissue – initiates
production of all blood cells)
* lymphoid tissue – found throughout body in
lymph nodes, tonsils, spleen, thymus (white
blood cells mature)
Blood
• formed elements – red blood cells, white
blood cells, platelets
-surrounded by a fluid matrix known as plasma;
transports gases, nutrients, and waste
Muscle Tissue
-consists of specialized cells that contain
protein filaments (parallel bundles) that cause
cells to contract (shorten and thicken)
-during contraction, actin filaments slide over
myosin filaments
3 types of muscle tissue
1) Skeletal Muscle – attached to bones by
tendons (bands of dense regular connective
tissue)
-located deep under skin
-voluntary (under conscious control)
-have striations – alternating dark/light bands
that show protein filaments
-multinucleated
2) Smooth (visceral) Muscle – forms part of
blood vessel walls and visceral organs
-contractions make substances move through
-involuntary (NOT under conscious control)
-no striations
-cells are spindle shaped
-single, centrally located nucleus
3) Cardiac Muscle – found in heart walls
(myocardium)
-contractions make heart pump blood
-involuntary
-striated
-intercalated disks – junctions between cardiac
cells
Nervous Tissue
-sends and carries electrochemical signals
throughout body
-2 types of cells (found in brain, spinal cord, and
nerves)
1) neurons – conduct message
2) neuroglia – support neurons (structural)
Membranes
-combinations of tissue (usually connective and
epithelium) forming a thin sheet
-divide areas of organs, line inside surfaces of
organs, anchor organs to other structures
3 types of epithelial membranes
1) Cutaneous membrane – skin
2) Serous membranes – line internal surfaces
of thoracic and abdominopelvic cavities, cover
organs in these cavities, bind organs to each
other and to body walls
-includes pericardium, pleural cavities,
peritoneum (lines abdominal cavities)
-secretes a clear, watery fluid (serous fluid) that
provides lubrication
3) Mucous membranes – line internal walls of
digestive tract from mouth to anus, respiratory
tract from nasal cavity to air sacs in lungs,
urinary tract, and reproductive tract
-secrete mucous – sticky, thick liquid composed
of water and carbohydrates
-trap/remove foreign particles, maintain moist
internal environment, protect cells from
harmful liquids (stomach acid)
Synovial Membranes
-line inside walls of cavities that surround
certain joints (knee, elbow, shoulder); no
epithelium, has loose connective tissue w/ fat
-secretes synovial fluid – lubricates bones and
nourishes cartilage