Lab 1
ANIMAL TISSUES
Levels of Organization
Animals are multicellular heterotrophs
whose cells lack cell walls.
Most animals exhibit a hierarchical level of
organization:
• Cells are organized into tissues
• Tissues combine to form organs
• Organs comprise organ systems
What is a tissue?
Group of similar cells that perform a
specialized function.
Examples include:
• Bone tissue
• Blood tissue
• Muscle tissue
4 basic types of animal tissue:
• Epithelial
• Connective
• Muscle
• Nervous
Epithelial Tissue
Characteristics:
 Cells fit closely together forming
continuous sheets
• Apical (free) surface
covers body surface or
lines interior of organs
• Basal surface adheres
to the basement
membrane
Epithelial Tissue
 Supported by connective tissue
 Avascular, but innervated
 Have remarkable powers of regeneration
Variety of functions depending on type
(protection, absorption, filtration, excretion,
secretion)
Epithelial Tissue
Classification based on # of cell layers
and shape of cells on apical surface.
 # of Cell Layers:
• Simple – one layer of cells
• Stratified – two or more layers
• Pseudostratified – simple, but appears
stratified
Epithelial Tissue
 Cell shape on apical surface:
• Squamous – flattened & scale-like
• Cuboidal – box-like
• Columnar – tall & column-like
Connective Tissue
Characteristics:
 Most are well vascularized
 Consists of widely-spaced cells and
fibers embedded in a non-living
extracellular matrix
Variety of functions depending on type
(support, binding other tissues, transport,
defense, storage)
Muscle Tissue
Characteristics:
 Well vascularized
 Packed with actin & myosin filaments
Function to contract producing most
types of body movements
Nervous Tissue
Characteristics:
 Composed of two types of cells:
• Neurons – specialized to generate and
transmit impulses; amitotic
• Neuroglia (glial cells) – protect, support &
insulate neurons
 Main component of the nervous system
(brain, spinal cord & nerves)
This week’s lab is devoted to
histology (the study of tissues).
Exercise A: Epithelial Tissues
 Simple squamous epithelium
Location – alveoli of lungs, lining of heart
& blood vessels
Function – allows diffusion of materials
surface view
lateral view
Exercise A: Epithelial Tissues
 Simple cuboidal epithelium
Location – kidney tubules & ducts; ovary
surface
Function – secretion & absorption
simple cuboidal
epithelium
basement
membrane
cross section
longitudinal section
Exercise A: Epithelial Tissues
 Simple columnar epithelium
Location – lines digestive tract from
stomach to the rectum
Function – absorption & secretion
Exercise A: Epithelial Tissues
 Pseudostratified columnar epithelium
Location – lining of trachea & upper
respiratory tract
Function – secretion & propulsion of mucus
ciliated cell
goblet cell
basal cell
basement membrane
connective tissue
cilia
Exercise A: Epithelial Tissues
 Stratified squamous epithelium
Location
• keratinized type: epidermis of skin
• non-keratinized type: linings of esophagus,
mouth & vagina
Function – protection
stratified
squamous
epithelium
Keratinized
connective
tissue
Non-keratinized
Exercise B: Connective Tissues
 Loose (areolar) connective tissue
Location – widely distributed under epithelia
Function – cushions organs
Gel-like matrix
Collagen fiber
Fibroblast nucleus
Elastic fiber
Exercise B: Connective Tissues
 Adipose
Location – under skin; around kidneys &
eyeballs; in breasts
Function – supports & protects organs;
insulates against heat loss; provides
reserve fuel
Exercise B: Connective Tissues
 Dense (fibrous) connective tissue
Location – tendons & ligaments
Function – attaches muscle to bone
(tendons) & bone to bone (ligaments)
Exercise B: Connective Tissues
 Hyaline cartilage
Location – covers ends of long bones; nose,
trachea & larynx
Function – support & reinforcement
Chondrocytes sitting
in lacunae (cavities)
Matrix packed with
collagen fibers
Exercise B: Connective Tissues
 Bone
Location – bones
Function – support & protection; calcium
storage; provides levers for muscles to act
on; site of blood cell production
Canaliculi
Central canal
Osteocyte sitting a
in lacuna (cavity)
Osteon
Exercise B: Connective Tissues
 Blood
Location – contained within blood vessels
Function – transport of gases (O2 & CO2),
nutrients & metabolic wastes
Red blood cells
Platelet
White blood cells:
• neutrophil
• monocyte
• lymphocyte
Plasma (liquid matrix)
Exercise C: Muscle Tissues
 Skeletal muscle
Long, cylindrical, multinucleate cells with
obvious striations
Location – attached to bones or
occasionally to skin
Function – voluntary movement
Nuclei
Striations
Exercise C: Muscle Tissues
 Cardiac muscle
Branched, uninucleate cells with striations
Location – walls of the heart
Function – contract involuntarily to propel
blood
Branched cell
Intercalated disc
Striations
Exercise C: Muscle Tissues
 Smooth muscle
Tapered, uninucleate, non-striated cells
Location – walls of hollow organs
Function – contract involuntarily to propel
materials along internal passageways
Nuclei
Circular layer
Longitudinal layer
Individual muscle cell
Exercise D: Nervous Tissue
 Neurons
cell body – contains nucleus
cytoplasmic processes:
• dendrites – transmit impulses to cell body
• axon – transmits impulses from cell body
Neuronal processes
(axons & dendrites)
Neuron cell
body
Neuron nucleus
Neuroglia