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Histology
The study of tissues
Homeostasis
• Maintenance of a constant internal
environment.
• We Don’t Like Stress.
• Physiology identifies and studies the
mechanisms of homeostasis.
• Controlled by Two Systems
– A.
– B.
Levels of Organization
Cells
Tissues
organs
organ system
organism
Tissues
groups of cells with a common structure and
function
Four categories
epithelial
connective
muscle
nervous
Epithelial tissue
location: outside of body, line organs and cavities
Function: barrier, absorption or secretion
– Glandular  secretory portion of gland
2 types
simple - one layer
stratified - multiple layers
“pseudostratified” appears stratified due to cells of
various lengths
Epithelial
tissue
Cell Shapes
squamous - floor tiles
cuboidal - dice
columnar - bricks on end
Simple Squamous
Leaky to allow
diffusion/osmosis.
Capillaries, alveoli.
May be keratinized
on body surfaces.
Connective Tissue
Basement
Membrane
Stratified Squamous
Readily sloughed
off.
Skin, anus,
vagina.
Connective
Tissue
Simple Cuboidal
Area of secretion or
absorption.
Stratified Cubiodal
Simple Columnar
Ciliated
Columnar
High secretion and
absorption, High SA/VOL
Lumen of vessel
Pseudostratified Columnar
Pseudostratified
Ciliated Columnar
Some cells do not reach the surface
Connective Tissue
MOST ABUNDANT TYPE OF TISSUE.
binds and supports other tissues, TRANSPORT,
FRAMEWORK, STORE ENERGY
cells create a matrix/ web of fibers
living web of fibers.]
3 kinds of fibers
collagenous fiber - made of collagen
Elastic fibers - Elastin Protein
reticular fibers - Thin collagen fibers
[Matrix non-
Types connective tissue
loose connective binds epithelia to underlying tissue; holds organs
1-Fibroblasts- secretes extracellular proteins
2-Macrophages- amoeboid WBC’s; phagocytosis
3-Adipose tissue- fat storage; insulation
Types of Connective Tissue
fibrous connective - parallel Bundles of cells
Ligaments, Tendons,
cartilage - collagen in rubbery matrix
bone - mineralized tissue
blood - liquid plasma matrix
Collagen
Tough, somewhat flexible protein. Provides the toughness of meats.
Very strong, resists longitudinal stress (tensile strength). Underlies
epithelial tissue.
Elastic fibers
Long threads of elastin.
Easily returns to original
shape (rubberband). This
is from an aorta. Also
found in skin and lungs.
Small, unbranched.
Secreted by fibroblasts.
Nuclei of Fibroblast
Loose Connective Tissue (areolar)
• Loose web of fibers (all
3)
• Fills space between
organs (Styrofoam
peanuts). Gel-like
matrix.
• Composed of elastin
(elasticity), collagen
(strength), reticular
fibers (support/form).
• Edema: excess
interstitial fluid absorbed
by LCT
Dense Connective tissue
Fibrous Connective Tissue.
Bundles of collagenous fibers.
Secreted by fibroblasts.
Non-elastic. Resists pulling
forces
Fxn: strong attachment
between structures (tendons
& ligaments)
Nuclei of Fibroblast
Hyaline
Cartilage
Elastic cartilage
Chondrocyte
Large amount of collagen, embedded in
chondroitin sulfate.
Provide rigid support. Nose, ear, trachea,
interverterbral disks.
Reduces friction on ends of long bones, absorbs
shock
Blood
R.B.C’s
W.B.C.
Neutrophil
Eosinophil
Connective tissue with liquid matrix (plasma). Two types of cells RBC’s
(Erythrocytes) and WBC’s (Leukocytes)
Plasma composed of H2O, NaCl, plasma proteins
Adipose (FAT)
Adipocyte
Nucleus
Support, protection, storage,
movement.
Bone
Osteocytes
Haversian System/ Canal
Osteocytes produce collagen
+ calcium phosphate 
hydroxyapatite
Muscle Tissue
long cells called muscle fibers
capable of contracting when
stimulated
3 types
Smooth - involuntary
Skeletal - voluntary
cardiac - walls of heart
Muscle
Skeletal Muscle
Cardiac Muscle
Fxn: Motion, Heat
production, maintain
posture.
Highly specialized for
contraction
Aka. Voluntary
Striated, branched.
Intercalated disks to speed
impulse.
Smooth Muscle
aka: visceral,
unstriated.
Surround hollow
structures (stomach,
blood vessels,
intestine, bladder.
Nervous tissue
neuron or nerve cell
specialized to transmit nerve impulses
Dendrites: transmit impulses from tips to rest of neuron
Axons: transmit impulses toward another neuron or effector
Neuron and Glial Cells
Nervous Tissue
Neuromuscular
Junction
Create a presentation: use
microscope pictures
Show the All types of epithelial:
simple squamous, simple cuboidal, stratified squamous,
simple columnar
tell what they are
where they would be located
SHow types of connective tissue and what they do:
adipose, cartilage, loose connective, ground bone (no longer a
ground bone slide)
show the 3 kinds of muscle tissue and how to tell
them apart:
Skeletal, cardiac, smooth
Show a neuron - what are the axons and dendrites?
- Use a web picture
• Organ systems…...
• Digestive-food processing
• Circulatory-internal distribution
• Respiratory-gas exchange
• Immune/Lymphatic-defense
Regulation of Internal
Environment
Interstitial fluid: internal environment of
vertebrates; exchanges nutrients and
wastes
Homeostasis: “steady state” or internal
balance
Negative feedback: change in a
physiological variable that is being
monitored
response counteracts the initial
fluctuation;
i.e., body temperature
i.e., uterine contractions at childbirth
Positive Feedback
Positive feedback:
physiological
control mechanism
in which a change
triggers mechanisms
that amplify the
change;
Metabolism: sum of all energy-requiring biochemical
reactions
Size vs. Metabolic Rate
Inverse relationship
Small = high metabolic rate
Large = low metabolic rate
Endotherms: bodies warmed by metabolic
heat
Ectotherms: bodies warmed by
environment
•
Basal Metabolic Rate (BMR): minimal
rate powering basic functions of life
(endotherms)
•
Standard Metabolic Rate (SMR): minimal
rate powering basic functions of life
(ectotherms)
Countercurrent exchange
Counter Current Common process
in multiple
systems
Heat exchange
example