Quiz 3 Flashcards
Epithelial Structure
cellularity
polarity
attachment
avascular
regeneration
cellularity
composed of cells in layers, connected by intercellular junctions
little ECM
polarity
apical (top) and basal (bottom) surfaces
attachment
to basal membrane- acellular surface produced by epithelia and connective cells
basal lamina- epithelial secretions
reticular lamina- connective secretions
avascular
no blood vessels
regeneration
cells readily divide mitotically and replace old cells
Epithelial function
physical protection
selective permeability (exchange and transport)
movement/clearing
secretion
sensation
Physical protection
from abrasion, dehydration, physical/chemical/biological agents
skin composed of five layers, cells held together by desmosomes
selective permeability
regulates passage of certain molecules in and out of body regions
exchange- passive flow
transport- active/facilitated flow
exchange epithelia
leaky exchange epithelia
allows movement through gaps between cells
transport epithelia
tight junctions prevent movement between adjacent cells
must pass through the epithelial cell (carriers and pumps involved)
clearing/movement
pushing material along the surface
cilia beat to move things out
microvilli increase surface area
sensory
receptors connected to nerve endings can detect light, chemical and mechanical stimuli and cold/heat
secretion
goblet cells
formation: epithelia folds in on itself, connecting cells then form a duct or connecting cells disappear for ductless
exocrine
duct
secrete to the exterior
endocrine
ductless
secrete to the body’s interior directly into blood stream or interstitial fluid
merocrine
secrete products by vesicular exocytosis
often continuous
ex. sweat and saliva
apocrine
secrete by partial cellular breakdown (fragmentation)
cytoplasm and vesicular contents
ex. milk and underarm sweat
holocrine
entire cell lost during secretion
stem cells divide to replace
ex. sebaceous glands
tight junctions
“gatekeeper”
prevent movement between adjacent cells
encircle cell near the apical surface- membrane protein is bound to plasma mem. of cell
adhering junctions
actin-filament based systems
encircle cell immediately adjacent to its neighbors, deep to tight juncts.
cadherins= cellular adhesion molecules
desmosomes
“snaps on a jacket”
tie cells together and do not encircle cell
allow bending and twisting and provide resistance to stress
supported by intermediate filaments
hemidesmosomes
tie cell to basal membrane
gap junctions
protein channels; allow rapid communication between cells
pore is made up of two hemi-channel connexon
connexons made up of a hexamer of connexin
Classifying Epithelia
SHAPE
- squamous=flat
- cuboidal=square
-columnar=elongated
NUMBER OF LAYERS
- simple=one layer
- stratified=many layers
Skeletal Structure
hard, elastic, tough connective tissue; internal endo-skeleton; scaffolding
articulated into many individual bones
protrusions have attachment sites
dense bone exterior, relatively open interior
Skeletal Function
support and protection of body and internal organs
connections to muscles, tendons, and ligaments (dynamic movement)
calcium/phosphate homeostasis and storage
blood cell production (stem cells in marrow)
Specialized cells of bone
osteoblasts= bone matrix deposition
osteocytes= bone matrix maintenance
osteoclasts= bone breakdown
specific matrix proteins of bone
collagen
flexible and tough, and the most abundant
ground substance of bone
hydroxyapatite
Two types of bone
cortical (compact) bone
cancellous (spongy) bone
Cortical bone
outside
dense “solid” outer layer
external layers of both long bone and flat bone
Cancellous bone
inside + porous
open interior with lattice
made up of narrow plates of bone called trabeculae
Osteon
“Haversion Canals”
functional unit of bone
cylinder of hollow tubes of bone matrix with a central canal carrying blood vessels and nerves
epiphysis
knobby region at each end of bone
provides strength and an attachment site
metaphysis
region between epiphysis and diaphysis
site of growth plate
diaphysis
elongated, cylindrical shaft of the bone
articular cartilage
located on epiphysis
prevents friction
periosteum
membrane of tough, dense, irregular connective tissue covering the external bone surface
endosteum
membrane of connective tissue covering the internal bone surface
medullary cavity
yellow marrow
inside of bone
epiphyseal plate
growth plate
What is stored in yellow marrow of the long bone?
fat
what is stored in red marrow of flat bone?
red and white blood cells
platelets
stress
force over area
pressure
load
strain
deformation in height
measured as %
Young’s modulus
slope
stress over strain
apply _____ and measure ____
stress
strain
stiff VS flexible
steep slope=stiff
shallow slope=flexibile
high VS low toughness
large area under curve=tough
brittle VS ductile
short plastic region=brittle
long plastic region=ductile
strong VS weak
high yield point=strong
low yield point=weak
hysteresis
historical dependence of behavior
anisotropy
directional dependence of behavior
exhibits different properties based on direction of loading
viscoelastic
materials show time-dependent strain
properties vary with speed and loading, appearing as different affects on stress rate in the curve
with low rates of stress bone is…
tough
with high rates of stress bone is…
strong
fracture patters reflect….
anisotropy
