How are epithelial tissues classified and held together? 9/24 This lecture content will be on...
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How are epithelial tissues classified and held together? 9/24 This lecture content will be on Test#2, not Mondays test #1 Chapter 5: 1) What is a tissue?
How are epithelial tissues classified and held together? 9/24
This lecture content will be on Test#2, not Mondays test #1 Chapter
5: 1) What is a tissue? 2) What is the embryonic pattern of
development that creates different tissues? 3) How do we view the
things we see with a microscope? 4) How are epithelial cells
classified? 5) Four types lack stacking 1- Simple squamous ET
characteristics 2- Simple cuboidal ET characteristics 3- Simple
columnar ET characteristics 4- Pseudostartified ET characteristics
6) Four types have stacking Stacking gives a tissue special
attributes Sign Up outside the AP lab for your special Lab Exam
time for next Wed or Thur.only one time per person.
Slide 2
How do we classify/describe the different cell types that make
up tissues, organs, organ systems and the body? Tissue: a set of
cells with similar appearance and function together in an organ.
How do we consider tissues? 1) Embryonic Origin: what cells were
the embryonic precursors? 2) Shape/Appearance: are cells round,
flat or cube etc? 3) Things leaving cells: Secretion vs. Excretion:
S: material has physiological function E: waste removal from
cell/body 4) Activity: Do cells use contraction, exocytosis,
endocytosis or phagocytosis? 5) Matrix: What extracellular material
is observed around the cells? Collagen, Elastin, Cartillage,
Interstitial Fluids These factors let us classify the tissue type!
Tissues classification lets us understand the cause/effects of
diseases.
Slide 3
How does the angle of observation affect what we observe? Two
dimensional interpretation of three dimensional objects can be very
difficult. Terms used to describe orientation of tissue section:
Longitudinal View vs. Cross Sectional View Oblique View: Mix of the
two for cells/tissue Histological fixing and sectioning of tissue
Object on Slide Histological Staining of tissue Colors on Slide
Sometimes fixation removes a part of the original tissue and what
is seen on the slide is the remnant of where the cell used to be.
The color we observe on a slide is usually created by the stains
the tissue was prepared with. Try to interpret what you see on a
slide as what it was.
Slide 4
What are our 3 Primary Germ Layers? Why are germ layers
improtant? #1: Life begins as a fertilized egg (zygote; Week 1)
that begins to divide. #2: Life progresses to a hollow ball of
cells with a yolk sac underneath (blastoceol; Week 2) Outside
surface=ectoderm Inside surface next to yolk sac= endoderm #3:
Week2-3 The ball of cells forms a neural tube (CNS). Cells squeeze
between the edges and migrate into the middle space between the
yolk sac and the outside.
Slide 5
How do the three primary germ layers create the four primary
classes of tissue? 1) Ectoderm: Epithelial Tissues Becomes:
epidermis, hair, glands of skin, nerves, brain, a few blood
vessels, and spinal cord Basement membrane holds them to underlying
base! 2) Endoderm: Epithelial Tissues Becomes lining of lungs and
glands of the gut 3) Mesoderm: Middle Tissues Becomes: dermis of
skin, muscle, blood and connective tissues Remember that cells can
migrate in the body during embryonic development. These 3 germ
layers create the 4 Primary Tissue Classes: 1) Epithelial 2)
Connective 3) Nervous 4) Muscular
Slide 6
The most fundamental way to organize epithelial cell classes is
by layer and cellular shape (Know Table 5.2). Four types have a
single epithelial cell layer: Simple Squamous Simple Cuboidal
Simple Columnar Psuedostratified Columnar Four types have layered
epithelial cells: Stratified Squamous 1)-with the protein keratin
2)-without the protein keratin 3)Stratified Cuboidal 4)Transitional
Why is the basement membrane so important? This is cellular
super-glue for all epithelial tissues! Why are underlying
connective tissues required?
Slide 7
Why is the shape of simple squamous epithelium important for
its function? Where is SSE: alveoli, blood vessels, serous membrane
of organs, glomerular capsule Key Characteristic: FLAT and THIN!
Typical packing and desmosomes: Why do we need a smooth surface?
Why do we need a thin barrier/membrane? Where does gas exchange
occur? Why does filtration occur? SSE tissues lining all blood
vessels consist of endothelial cells Additional Endothelial
Functions: Hormonal functions- Contraction, inflammation and
permeability- Clot Prevention-
Slide 8
Simple cuboidal epithelium helps with: protection, secretion
and reabsorption. Key characteristic: CUBE SHAPED! Tight packing:
Desmosomes: Provides Glandular Functions (Secretions): ovary,
salivary, thyroid, pancreas, and liver Kidney has dual functions:
Absorption and Secretion-
Slide 9
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Slide 10
How do we protect cells and underlying tissues in places, such
as the stomach? How do we prevent acids, abrasives, or pathogenic
organisms from damaging underlying tissues? Simple Columnar
Epithelium: Longer than they are wide to put nuclei by basement
membrane for extra safety: Tough basement membrane: SCEs secrete
digestive enzymes: SCEs help with nutrient absorption: Some have
cilia (uterine tubes): Huge intestinal surface area with villi
(cells) and microvilli (cell structures)= nutrient/water absorption
Specialized Goblet cells make mucus to lubricate the passage of
materials
Slide 11
Pseudostratified Columnar Epithelium (PCE) has cilia that move
materials embedded in mucus in a single direction. Why is it called
pseudostratified? Nuclei are at several different levels in cell-
All cells still reach basement membrane- It only appears
multi-layered Goblet cells are important! Importance of cilia for
the airways? Importance of cilia in male reproductive tract?
Importance of basement membrane?
Slide 12
Slide 13
Stratified Epithelial cells (Table 5.3) can be: 1) Squamous
with keratin 2) Squamous without keratin, 3) Cuboidal or 4)
Transitional. Callus on Sole of Foot: SSE-K...creates a nasty water
insoluble place where bacteria cant live and water cant evaporate
from the body!why? Mucosa of vagina, mouth, anus, esophogus are
covered by: SSE-NoKwhy? Ovarian follicles and seminiferous tubules
of the testes: SCEwhy? Transitional Epithelium: Lower urinary tract
and part of umbilical cord- it stretches! Why transitional (partly
rounded/partly flattened)? WHAT IS EPITHELIAL CELL EXFOLIATION? Do
you treat the exfoliation on your scalp?
Slide 14
The Eight Kinds of Epithelial Tissue: Describe the key features
of each and where they are found in the body: Four Single Layer
Epithelial Tissues: Simple Squamous Epithelial Simple Cuboidal
Epithelial Simple Columnar Epithelial Pseudostratified Columnar
Epithelial Four Layered Epithelial Tissues: Stratified Squamous
Epithelium-Keratinized Stratified Squamous
Epithelial-Nonkeratinized Stratified Cuboidal Epithelial
Transitional Epithelial