Exam 1

Front 1

name the 3 most common types of cell junctions

Back 1

tight junction, gap junction, and desmosomes

Front 2

large areas of opposing PMs are interconnected by transmembrane proteins called __________. give an example of where these are located.

Back 2

cell adhesion molecules or CAMs; bind to each other and extracellular materials; CAMs on the basolateral surface of an epithelium help bind the cell to the underlying basement membrane.

Front 3

describe hyaluronan (hyaluronic acid)

Back 3

The membranes of adjacent cells may also be bonded by a thin layer of proteoglycans that contain polysaccharide derivatives known as glycosaminoglycans, most notably hyaluronan (hyaluronic acid).

Front 4

describe tight junction and where you may find cells that contain them

Back 4

At a tight junction, the lipid portions of the two plasma
membranes are tightly bound together by interlocking membrane
proteins (Figure 4–2b). Inferior to the tight junctions, a
continuous adhesion belt forms a band that encircles cells and
binds them to their neighbors. The bands are attached to the microfilaments
of the terminal web. p. 69 This kind of attachment
is so tight that these junctions largely prevent the passage of
water and solutes between the cells. When the epithelium lines a
tube, such as the intestinal tract, the apical surfaces of the epithelial
cells are exposed to the space inside the tube, a passageway
called the lumen (LOO-men). Tight junctions effectively isolate
the contents of the lumen from the basolateral surfaces of the
cell. For example, tight junctions near the apical surfaces of cells
that line the digestive tract help keep enzymes, acids, and wastes
in the lumen from reaching the basolateral surfaces and digesting
or otherwise damaging the underlying tissues and organs.

Front 5

describe gap junction and where you may find cells that contain them

Back 5

Some epithelial functions require rapid intercellular communication.
At a gap junction (Figure 4–2c), two cells are
held together by two interlocking transmembrane proteins

called connexons. Because these are channel proteins, they form
a narrow passageway that lets small molecules and ions pass
from cell to cell. Gap junctions are common among epithelial
cells, where the movement of ions helps coordinate functions
such as the beating of cilia. Gap junctions are also common in
other tissues. For example, gap junctions in cardiac muscle tissue
and smooth muscle tissue are essential to the coordination
of muscle cell contractions.

Front 6

describe desmosomes (2 types) and where you may find cells that contain them

Back 6

A typical desmosome is formed by two cells. Within each
cell is a complex known as a dense area, which is connected to
the cytoskeleton (Figure 4–2d). It is this connection to the cytoskeleton
that gives the desmosome—and the epithelium—its
strength. For example, desmosomes are abundant between cells
in the superficial layers of the skin. As a result, damaged skin
cells are usually lost in sheets rather than as individual cells.
(That is why your skin peels rather than comes off as a powder
after a sunburn.)
There are two types of desmosomes:
• Spot desmosomes are small discs connected to bands of intermediate
filaments. The intermediate filaments function to
stabilize the shape of the cell.
• Hemidesmosomes resemble half of a spot desmosome.
Rather than attaching one cell to another, a hemidesmosome
attaches a cell to extracellular filaments in the basement
membrane (Figure 4–2e). This attachment helps
stabilize the position of

Front 7

location and function of: simple squamous epithelium

Back 7

LOCATIONS: Mesothelia
lining ventral body cavities;
endothelia lining heart
and blood vessels; portions
of kidney tubules (thin
sections of nephron loops);
inner lining of cornea;
alveoli of lungs

FUNCTIONS: Reduces
friction; controls vessel
permeability; performs
absorption and
secretion

Front 8

location and function of: stratified squamous epithelium

Back 8

LOCATIONS: Surface of
skin; lining of mouth, throat,
esophagus, rectum, anus,
and vagina

FUNCTIONS: Provides physical
protection against abrasion,
pathogens, and chemical attack

Front 9

location and function of: simple cuboidal epithelium

Back 9

LOCATIONS: Glands; ducts;
portions of kidney tubules; thyroid
gland

FUNCTIONS: Limited protection,
secretion, absorption

Front 10

location and function of: stratified cuboidal epithelium

Back 10

LOCATIONS: Lining of some ducts
(rare)

FUNCTIONS: Protection, secretion,
absorption

Front 11

location and function of: transitional epithelium

Back 11

LOCATIONS: Urinary
bladder; renal pelvis;
ureters

FUNCTIONS: Permits
expansion and recoil
after stretching

Front 12

location and function of: simple columnar epithelium

Back 12

LOCATIONS: Lining of
stomach, intestine, gallbladder,
uterine tubes, and collecting
ducts of kidneys

FUNCTIONS: Protection,
secretion, absorption

Front 13

location and function of: pseudostratified ciliated columnar epithelium

Back 13

LOCATIONS: Lining of
nasal cavity, trachea, and
bronchi; portions of male
reproductive tract

FUNCTIONS: Protection,
secretion, move mucus
with cilia

Front 14

location and function of: stratified columnar epithelium

Back 14

LOCATIONS: Small areas of
the pharynx, epiglottis, anus,
mammary glands, salivary
gland ducts, and urethra

FUNCTION: Protection

Front 15

what are the 3 types of exocrine glands?

Back 15

merocrine, aprocrine, and holocrine

Front 16

describe merocrine secretion

Back 16

In merocrine secretion (MER-u-krin; meros, part), the
product is released from secretory vesicles by exocytosis
(Figure 4–6a). This is the most common mode of secretion.
Mucin is one type of merocrine secretion that mixes withwater to
form mucus. Mucus is an effective lubricant, a protective barrier,
and a sticky trap for foreign particles and microorganisms. The
mucous secretions of the salivary glands coat food and reduce
friction during swallowing. In the skin, merocrine sweat glands
produce the watery perspiration that helps cool you on a hot day.

Front 17

describe apocrine secretion

Back 17

Apocrine secretion( ; apo-, off) involves the loss
of cytoplasm as well as the secretory product (Figure 4–6b).
The apical portion of the cytoplasm becomes packed with secretory
vesicles and is then shed. Milk production in the mammary
glands involves a combination of merocrine and apocrine
secretions.

Front 18

describe holocrine secretion

Back 18

Holocrine secretion
(HOL-o ; holos, entire), by contrast, destroys the gland cell. During holocrine secretion, the entire cell becomes packed
with secretory products and then bursts (Figure 4–6c), releasing
the secretion, but killing the cell. Further secretion depends
on the replacement of destroyed gland cells by the division of
stem cells. Sebaceous glands, associated with hair follicles, produce
an oily hair coating by means of holocrine secretion.

Front 19

what are the 3 types of secretions and describe each?

Back 19

Serous glands secrete a watery solution that contains enzymes.
The parotid salivary glands are serous glands.
• Mucous glands secrete mucins that hydrate to form mucus.
The sublingual salivary glands and the submucosal glands
of the small intestine are mucous glands.
• Mixed exocrine glands contain more than one type of gland
cell and may produce two different exocrine secretions, one
serous and the other mucous. The submandibular salivary
glands are mixed exocrine glands.

Front 20

what are the 2 general gland structures?

Back 20

Unicellular glands and multicellular glands. multicellular glands include glandular epithelia and
aggregations of gland cells that produce exocrine or endocrine
secretions.
The only unicellular exocrine glands in the body are
mucous (goblet) cells, which secrete mucins. Mucous cells are
scattered among other epithelial cells. Both the pseudostratified
ciliated columnar epithelium that lines the trachea and the
columnar epithelium of the small and large intestines have an
abundance of mucous cells.
The simplest multicellular exocrine gland is a secretory
sheet, in which gland cells form an epithelium that releases secretions
into an inner compartment. The continuous secretion
of mucin-secreting cells that line the stomach, for instance, protects
that organ from its own acids and enzymes. Most other
multicellular exocrine glands are in pockets set back from the
epithelial surface; their secretions travel through one or more
ducts to the surface. Examples include the salivary glands,
which produce mucins and digestive enzymes.

Front 21

list the different types of multicellular gland structures. where might you find these specific gland types?

Back 21

simple vs compound. coiled vs branched. tubular vs alveolar.

simple tubular; intestinal

simple coiled tubular; merocrine sweat

simple branched tubular; gastric, mucuous in esophagus and duodenum

simple alveolar; not found but stage in development of simple branched glands

simple branched alveolar; sebaceous

compound tubular; mucous glands in mouth, bulbo-urethral in males, testes

compound alveolar; mammary

compound tubuloalveolar; salivary, respiratory passages, pancreas

Front 22

what are the 3 fibers types in connective tissue?

Back 22

Three types of fibers occur in connective
tissue: collagen, reticular, and elastic. Fibroblasts form all three
by secreting protein subunits that interact in the matrix. Fibrocytes
are responsible for maintaining these connective tissue fibers.

Front 23

describe collagen fibers.

Back 23

Collagen fibers are long, straight, and unbranched. They
are the most common fibers in connective tissue proper.
Each collagen fiber consists of a bundle of fibrous protein
subunits wound together like the strands of a rope. Like a
rope, a collagen fiber is flexible, but it is stronger than steel
when pulled from either end. Tendons, which connect
skeletal muscles to bones, consist almost entirely of collagen
fibers. Typical ligaments are similar to tendons, but they
connect one bone to another. Tendons and ligaments can
withstand tremendous forces. Uncontrolled muscle contractions
or skeletal movements are more likely to break a
bone than to snap a tendon or a ligament.

Front 24

describe reticular fibers.

Back 24

Reticular fibers (reticulum, network) contain the same
protein subunits as do collagen fibers, but arranged differently.
Thinner than collagen fibers, reticular fibers form a
branching, interwoven framework that is tough, yet flexible.
Because they form a network rather than share a common alignment, reticular fibers resist forces applied from
many directions. This interwoven network, called a stroma,
stabilizes the relative positions of the functional cells, or
parenchyma (pa-RENG-ki-ma), of organs such as the liver.
Reticular fibers also stabilize the positions of an organ’s
blood vessels, nerves, and other structures, despite changing
positions and the pull of gravity.

Front 25

describe elastic fibers.

Back 25

Elastic fibers contain the protein elastin. Elastic fibers are
branched and wavy. After stretching, they will return to
their original length. Elastic ligaments, which are dominated
by elastic fibers, are rare but have important functions,
such as interconnecting vertebrae.

Front 26

what are the 4 types of membranes?

Back 26

The membranes
we are concerned with here line or cover body surfaces.
Each consists of an epithelium supported by connective tissue.
Four such membranes occur in the body: mucous, serous, cutaneous, and synovial

Front 27

describe mucous membranes

Back 27

Mucous membranes, or mucosae ( ), line passageways
and chambers that communicate with the exterior, including
those in the digestive, respiratory, reproductive, and
urinary tracts (Figure 4–16a). The epithelial surfaces of these
passageways must be kept moist to reduce friction and, in many
cases, to facilitate absorption or secretion. The epithelial surfaces are lubricated either by mucus, produced by mucous cells
or multicellular glands, or by exposure to fluids such as urine
or semen. The areolar tissue component of a mucous membrane
is called the lamina propria ( ). We will consider
the organization of specific mucous membranes in greater
detail in later chapters.
Many mucous membranes contain simple epithelia that
perform absorptive or secretory functions, such as the simple
columnar epithelium of the digestive tract. However, other
types of epithelia may be involved. For example, a stratified
squamous epithelium is part of the mucous membrane of the
mouth, and the mucous membrane along most of the urinary
tract contains a transitional epithelium.

Front 28

describe serous membranes

Back 28

Serous membranes line the sealed, internal subdivisions of
the ventral body cavity—cavities that are not open to the exterior.
These membranes consist of a mesothelium supported by
areolar tissue (Figure 4–16b). As you may recall from Chapter
1, the three types of serous membranes are (1) the pleura, which
lines the pleural cavities and covers the lungs; (2) the
peritoneum, which lines the peritoneal cavity and covers the surfaces
of the enclosed organs; and (3) the pericardium, which
lines the pericardial cavity and covers the heart. p. 21 Serous
membranes are very thin, but they are firmly attached to the
body wall and to the organs they cover. When looking at an organ
such as the heart or stomach, you are really seeing the tissues
of the organ through a transparent serous membrane.
Each serous membrane can be divided into a parietal portion,
which lines the inner surface of the cavity, and an opposing
visceral portion, or serosa, which covers the outer surfaces of visceral organs. These organs often move or change shape as
they perform their various functions, and the parietal and visceral
surfaces of a serous membrane are in close contact at all
times. Thus, the primary function of any serous membrane is
to minimize friction between the opposing parietal and visceral
surfaces. Friction is kept to a minimum because mesothelia
are very thin and permeable; tissue fluids continuously
diffuse onto the exposed surface, keeping it moist and slippery.
The fluid formed on the surfaces of a serous membrane is
called a transudate( ; trans-, across). In healthy individuals,
the total volume of transudate is extremely small—
just enough to prevent friction between the walls of the cavities
and the surfaces of internal organs. However, after an injury or in certain disease states, the volume of transudate may increase
dramatically, complicating existing medical problems or producing
new ones.

Front 29

describe cutaneous membranes

Back 29

The cutaneous membrane, or skin, covers the surface of the
body. It consists of a stratified squamous epithelium and a layer
of areolar tissue reinforced by underlying dense irregular connective
tissue (Figure 4–16c). In contrast to serous and mucous
membranes, the cutaneous membrane is thick, relatively waterproof,
and usually dry. We will examine the cutaneous membrane
further in Chapter 5.

Front 30

describe synovial membranes

Back 30

Adjacent bones often interact at joints, or articulations. At an articulation,
the two articulating bones are very close together or
in contact. Joints that permit significant amounts of movement
are complex structures. Such a joint is surrounded by a fibrous
capsule, and the ends of the articulating bones lie within a joint
cavity filled with synovial( ) fluid (Figure 4–16d).
The synovial fluid is produced by a synovial membrane,
which lines the joint cavity. A synovial membrane consists of an
extensive area of areolar tissue containing a matrix of interwoven
collagen fibers, proteoglycans, and glycoproteins. An incomplete
layer of macrophages and specialized fibroblasts
separates the areolar tissue from the joint cavity. These cells regulate
the composition of the synovial fluid. Although this lining
is often called an epithelium, it differs from true epithelia
in four respects: (1) It develops within a connective tissue,
(2) no basement membrane is present, (3) gaps of up to 1 mm
may separate adjacent cells, and (4) fluid and solutes are continuously
exchanged between the synovial fluid and capillaries
in the underlying connective tissue.
Even though a smooth layer of articular cartilage covers the
ends of the bones, the surfaces must be lubricated to keep friction
from damaging the opposing surfaces. The necessary lubrication
is provided by the synovial fluid, which is similar in composition
to the ground substance in loose connective tissues. Synovial
fluid circulates from the areolar tissue into the joint cavity and percolates through the articular cartilages, providing oxygen and
nutrients to the chondrocytes. Joint movement is important in
stimulating the formation and circulation of synovial fluid: If a
synovial joint is immobilized for long periods, the articular cartilages
and the synovial membrane undergo degenerative changes.

Front 31

describe the effects of aging on tissues

Back 31

Two important effects of aging on tissues: the body’s decreased ability to repair damage to tissues, and an increase in the occurrence of cancer.

Tissues change with age, and the speed and effectiveness of tissue
repairs decrease. Repair and maintenance activities
throughout the body slow down; the rate of energy consumption
in general declines. All these changes reflect various hormonal
alterations occurring with age, often coupled with a
reduction in physical activity and the adoption of a more
sedentary lifestyle. These factors combine to alter the structure
and chemical composition of many tissues. Epithelia get thinner
and connective tissues more fragile. Individuals bruise easily
and bones become brittle; joint pain and broken bones are
common in the elderly. Because cardiac muscle cells and neurons
are not normally replaced, cumulative damage can eventually
cause major health problems, such as cardiovascular
disease or deterioration in mental functioning.