Unit 2: Histology Flashcards
Define Tissues
collection of cells & cell products; that perform specific limited functions
4 Basic Tissue Types;
- Muscle
- Nervous
- Connective
- Epithelial
Define Epithelial tissue function
covers exposed surfaces (lining)
lines internal pathways
forms glands
Define Connective Tissue function
fills internal spaces- packing materia;
supports other tissues- bone & cartilage
transport materials- blood and lymph
stores energy - adipose tissue- fat
extracellular matrix: non-cellular, non-living parts of CT; can have protein fibers
Define muscle tissue function
contraction (in blood vessels & organs)- does not put itself back
name 3 types of muscle tissue & function
skeletal- voluntary
cardiac- found in walls of hollow organs
smooth
Define function of neural tissue
conducting electrical impulses
2 different types of epithelial tissue
- epithelial
- glandular
Define epithelia
layers of cells covering internal or external surfaces
ex. epidermis
define glands
structures that produce secretion
What are the 5 characteristics of epithelia?
- Cellularity
- polarity
- attachment
- avascularity
- regeneration
Define the characteristic of epithelial: cellularity
When cells are closely bound together (so they can regulate what can enter the body) by structures called- cell junctions
other tissue types are separated by ECM
Define the characteristic of epithelial: Polarity
refers to the presence of structural and functional differences
What are the two sides of polarity found in epithelia?
apical surface- top surface
basolateral surface- bottom and the sides
- attached to another cell or basement membrane and the sides which contract neighboring cells
Define the characteristic of epithelial: Attachment
epithelia are anchored to a layer of extracellular material- basal lamina or basement membrane (
Define the characteristic of epithelial: Avascularity
No blood vessels- must obtain nutrients through diffusion to absorption usually through CT
Define the characteristic of epithelial: regeneration
the rate of cell division & regeneration is higher than other tissues
- constantly getting rid of top layer- self-cleaning epidermis
new epidermis every 4-6 weeks
epithelial lining: wear and tear
List teh 4 functions of epithelial tissue
- provide physical protection
- control permeability
- provide sensation
- provide specialized functions
How does epithelial tissue provide physical protection?
the epidermin prptects the inside of the body from abrasions, microbes, chemicals and dehydration
What are some examples of epithelial tissue monitoring permeability?
The epithelial lining of intestine, kidneys and lungs monitors what’s going in and out
How does the epithelial tissue produce sensation?
through highly specialized cells
ex. taste buds, eyes and ears
What is an example of epithelial tissue providing highly specialized functions?
glandular epithelial tissues
List 3 ways in how epithelial cells specialize
- moving or pushing materials over the epithelial tissue
- absorption
- secretion
Give an example of moving or pushing materials over the epithelial tissue?
function of ciliated epithelial
e.g. lining of respiratory passageways to move mucus
Define cilia
hair-life orgalles that wave or beat (rhythmic movement)
- cell has 250 cilia that beat in a coordinate manner
Example of epithelial tissue role in absorption
absorbing nutrients from intestine
example of epithelial tissue roles in secretion
mucus
What is absorption and secretion aided by? Define it and what do they do
Microvilli- tiny bumps of cell membrane
increases SA and absorbs more stuff= efficient
ex. lining of small intestine
Explain the concept of intracellular connections to epithelial tissue
gives strength to epithelial tissue & help them communicate with each other
What does intracellular connections involve ? (2)
- extensive areas of adjacent cell membranes
- specialized cell junctions
Define cell adhesion molecules
transmembrane proteins that interconnect large areas of adjacent cell membranes
- can bind to each other or the basement membrane
Name 3 catgeories of cell junctions
- tight junction
- gap junctions
- desmosomes
a. spot desmosomes
b. hemidesmosomes
define cell junctions
specialized areas of the plasma membrane that attach a cell to another cell or to extracellular materials
define tight junction
between apical portions of adjacent cells
- bound tightly –>prevents water and other substances from leaking b/w the cells
- useful when epithelium lines a tube e.g. intestine
define gap junctions
allow rapid communication b/w the 2 connected cells- communication helps coordinate function
e.g. beating of cilila
- found in cells where communication takes place
e.g. heart muscles & contractions fo smooth muscle cells
- 2 neighboring cells held together by channel; proteins
-allow ions and small molecules to pass cell to cell
Define desmosomes
ensure stretching or twisting- very stronng
e.g. superficial layers of ski
- skin peels due to it
define spot desmosomes
ties adjacent cells together
define hemidesmosomes
attach a cell to extracellular structures such as protein fibers in the basement membrane
Define basement membrane
made of layers of proteins that strengthen epithelia
-help form a barrier b/w epithelia & underlying tissue
What is classification of epithelia based on?
based off of cell shape
# of layers
What are 3 epithelia cell shapes? w/ description & ex
squamos- thin and flat
cuboidal- squarish
columnar- tall slender rectangle
What are the 2 # of layers for epithelia? w/ description & ex
stratified- several layers of cells ex. callus
simple- a single layer of cells ex. oxygen diffusion
What is simple epithelium good for? w/ ex.
where substances need to be absorbed through the epithelium
e.g. lining of lungs, lining of intestines
What is stratified epithelia good for? w/ ex
good for areas that need protection from wear and tear & friction
e.gi epidermis, lining of thorat
Define germinative cells
type of stem cells that epithelial cells grow from; located near the basement membrane
Defne glands
collection of epithelial cells that produces secretion
Define endocrine glands
secretes chemical messengers called hormones which get released into bodily fluids
- ductless glands
Define exocrine glands
release secretions into ducts that open onto an epithelial surface
- ducts empty onto the skin surface or an epithelium lining
Examples of exocrine glands
perspiration fo skin, tears, mucus, milk–> mammary glands, saliva, enzymes entering the digestive tract
List the 3 modes of secretion
- merocrine secretion
- apocrine secretion
- holocrine secretion
Describe merocrine secretion
most common form of secretion
product packaged into secretory vesicles & released from the vesicles by exocytosis
Describe apocrine secretion
“apo” apical portion of the cell (top)
products is released when the apical portion of the cell pinches off and breaks down
some cytoplasm is lost w. the secretory product
- the cell can regenerate a new apical region & start over r
Example of apocrine secretion
cells of mammary glands release milk this way
How would you differentiate between apocrine secretion and merocrine secretion?
You would look for cytoplasm to differentiate from merocrine
Describe holocrine secretion
product is released when the cells burst which kills the gland cell; destroys the whole gland cell
- gland cell gets replaced with division of stem cells (germinative cells)
Ex of holocrine secretion
cells of sebaceous gland–> sebum; oil glands in skin
list 2 TYPES of secretions
- serous secretions
- Mucus glands
Describe serous secretions
watery solutions that contain proteins- enzymes
ex of serous secretions
gastric chief cells
describe mucous secretions
the gland cells secretes molecules called mucins–> which mix w. water to form mucus
ex. of mucuous secretions
various digestive glands produce mucus
Function of mucus
protect the digestive tract from harsh digestive juices
Goblet cells define
the only unicellular exocrine glands; secretes mucins
define mesenchyme
what ct arrise from an embryonic tissue
what are 3 characteristic of CT?
- specialized cells
- extracellular protein fibers
- fluid extracellular ground substance
–> extracellular matrix
difference between CT and ET
Et lines passageways that lead to the outside worlds
Ct is always inside
ET is avascular
CT is vascular (except cartilage)
both has sensory receptors
define ground substance
thicker and stickier than normal ECM fluid
Define matrix & describe
noncellular non-living parts of CT
-made of protein fibers & ground substance
- made by CT cells
Makes ups most of the tissue volume
martix differs with different Ct
list 3 classifications of CT
- connective tissue proper (CTP)
- Fluid connective tissue
- Supporting CT
define CTP
connect & protect
what tendons and ligaments are made out of
define and give an ex. of fluid connective tissue
2- blood & lymph
transport things in body
watery matric w/ dissolved porteins –> can be transformed into solid form for blood clotting
give ex. of supporting ct
bone and cartilage
List 7 cells of CTP
fibroblast, adipocytes, mesenchymal cells, macrophages, mast cells, melanocytes, and lymphocytes
Define fibroblast
most common cell type in CTP
- produce ground substance & extracellular protein fibers - a lot of protein fibers is collagen
define adipocytes
store energy in form of lipid molecule
define mesenchymal cells
stem cells, can divide to make fibroblasts, adipocytes, or other CT cells
define macrophage and identify 2 types & define
white blood cell (WBC); engulf & destroy pathogens and other stuff, dead cells
free macrophages- move like amoeba
fixed macrophage
define mast cells
trigger local inflammation by releasing chemicals
e.g. histamines
define melanocytes
produce melanin- brown pigmentation in skin
specifically around nuclei to protect the DNA
- UV rays make vitamin D
define lymphocyte
WBC’s –> specific defenses
basis for immunity and vaccines; include T- cells and B-cells
plasma cells aka plasma B- cells make antibodies
List 3 fibers in CTP
- collagen fibers
- reticular fibers
- elastic fibers
define collagen fibers and e.g
what are they a major component of?
give e.g.
major component of tendons and ligaments
gives strength to many tissues
e.g. skin bones
define reticular fibers
forms a branched network to support structure of organs
define elastic fibers
similar to collagen fibers - made of protein elastin –> stretches and bounces back to original state
-rare compared to collagen fibers
e.g. of elastic fiber
ligaments that interconnect the vertebrae
list the 2 categories of CTP
- loose CT
- Dense CT
Define loose CT
more ground substance
fewer protein fibers e.g. adipose tissue
the packaging of material of the body - fills in the spaces cushioning the body
list the 3 types of loose CT
- areolar tissue
- adipose tissue
- reticular tissue
define areolar tissue
least specialized & most generic type of tissue
viscous (thick) ground substance
- has some elastic fibers
- holds blood vessels and capillary beds
e.g. of areolar tissue
find under the skin; subcutaneous layer
Define adipose tisue
adipocytes; store fat, insulation & slowly heat loss
What happens to adipocytes during fat loss or gain?
expand and shrink based off fat loss and gain
(same thing with muscle cells)
don’t divide
define reticular tissue
reticular fibers; complex 3D network
provides support & maintains the shape of organs
e.g. of reticular tissue
spleen, liver, lymph nodes, bone marrow
Define Dense CT & e.g.
more fibers
less ground substance
e.g. what tendons and ligaments are made out of
-tightly packet w/ collagen and/or collagen fibers
list 3 categories of dense CT
- Dense regular CT
- dense irregular CT
- elastci tissue
define dense regular CT
tightly packed parallel collagen fibers
-> has strength to withstand forces coming from one direction
- good for tendons and ligaments- stresses on these structures come from predictable directions
define tendons
attach muscles to bones
define ligaments
attach bones ot bones
ligaments stabilize position for organs
define aponeuroses
made up of broad, flat sheets of dense regular CT
-also attach muscles to bones
define dense irregular CT & e.g.
interwoven networks of collagen fibers; no organized pattern;strength in all directions
e.g. skin (leather)
forms capsules & sheaths that surrounds organs
define periosteum
around bones
define perichondrium
around cartilages
define elastic tissue & e.g.
dense regular CT dominated by elastic fibers (instead of collagen)
e.g. in the elastic ligaments that connect vertebrae
What is the plasma?
matrix of the blood
3 types of blood cells
RBCs
WBCs
platelets
define RBCs
how much do they take up the volume of blood?
erythrocytes; make up approximately 1/2 volume of blood
carry CO2 in blood
define WBCs
leukocytes
- 20 different types; various immune function
define platelet
not cells; cell fragments
sticky- good for blood clotting
define lymph
a fluid collected from interstitial space ( space b/w cell in tissues)
flows through lymphatic vessels & closely monitored by immune system
eventually becomes part of blood plasma when it returns to large veins near the heart
list 3 major subdivisions of ECF (extracellular fluid)
- plasma
- interstitial fluid
- lympth
what is the origin of interstitial fluid?
when blood flows through capillaries blood pressure forces water & small solutes through the walls of capillaries
define interstitial fluid
bathes cells in tissues
where does lymph end up?
2 large lymphatic vessels located under the clavicle (collarbone)
goes to subclavian veins- goes to blood & becomes plasma
Calcified define?
Bone made rigid by calcium & other minerals
define cartilage
ground substances is very thick gel material
Where are chondrocytes located?
lacuna- a scooped out area w/in the thick gel matrix
describe cartilage
avascular (unusual for tissues) & heats poorly
gets O2 and nutrients by slow diffusion through the thick, dense matrix
list 3 types of cartilage
- hyalin cartilage
- elastic cartilages
- fibro cartilage
define hyaline cartilage
glossy; the most common type
tough yet somewhat flexible
e.g. of hyaline cartilage
trachea and nasal
define elastic cartilage
supporting but bends easily
found in the external ear
ear- pinna or auricles
epigottis- flap that covers the larynx
define fibrocartilage
very tough- the toughest cartilage
- prevents bone ot bone contact
e.g. of fibrocartilage
in knee joints, in the intervertebral discs- cartilage b/w the vertebrae
2 types of growth of cartilage
interstitial growth
appositional growth
define interstitial growth
cell division & additional matrix from within the interior of the cartilage
- womb & throughout childhood
define appositional growth
cell division & additional matricx around the outside surface
- used to repair damaged cartilage in adulthood
what is bone also called?
osseous tissue
what is 2/3 of the bone matrix?
mineral portion; calcium salts
what is 1/3 of the bone matrix?
collagen fibers- bone can bend before fracturing; resists shattering
Where are bone cells called and where do they reside”?
osteocytes ; small chambers called lacunae (same as chondrocytes)
How are osteocytes arranged?
arranged in circular layers around central canals- contain small blood vessels w/in the bone matrix
define canaliculi
bone cells access the blood supply through small channels that run through bone matrix
Role & description of tissue membranes
line or cover bone sufaces
- consist of an epithelial layer w/ a supporting layer of CT underneath - areolar tissue
Nam the 4 types of tissue membranes
- mucous membranes
- serous membranes
- the cutaneous membrane
- synovial membrane
define mucous membranes,
lines passageways that connect to the outside world and keeps the surface moist w/ mucus
e.g. of mucous membranes lining___
digestive, respiratory, urinary, repro tratcs
What is mucous produced by>
goblet cells or multicellular glands
How does mucous membrane facilitate absorption?
by absorbing O2 in the lungs
define serous membranes
line sealed internal areas of the ventral body cavity
thin, transparent but strong
what does serous membranes produce and what does it do?
produce a slippery fluid= transudate
- minimizes wear and tear in ventral cavity
define the cutaneous membrane
skin- covers body surface
stratified-squamous epithelial- epidermis
What is below the epidermis?
dense irregular Ct & areolar tissue= dermis
Differences between the cutaneous membrane and the other membranes
skin is thick, somewhat waterproof, and relatively dry
Define synovial membranes & what does it produce
line moving joint cavities
produce synovial fluid-> lubricates and protects the ends of bone in joints
Why do bone cells heal faster than cartilage?
because it has access to bone supply unlike cartilage
Define fasciae and function
CT layers and wrappings which support and surround organs
maintain the position of roagsn
provides routes for blood vessels, lymphatics, and nerves
Name 3 types of fascia
- superficial fascia
- deep fascia
- subserous fascia
define superficial fascia
aka hypodermis aka subcutaneous layer
layer of fat below the skin; separates the skin from underlying tissues & organs
Why do injection go in this layer?
there are no muscles or tendons
it is squishy fat loaded w/ blood vessels
what is superficial fascia made up of?
areolar and adipose tissue
Define deep fascia
made up of dense irregular CT- tough capsules around organs, bones, tendons, ligaments, cartilages and muscles
What function does deep fascia do?
its leathery wrapping paper
does a lot of the framework (more collagen)
does not hold the structure
protects and holds in place
Define subserous fascia
made up of areolar tissue; separate deep fascia from the serous membranes (lines body cavities)
