Animal Cells and
Tissues
AP Biology
Animal Cells and Tissues
Four tissue types:
Epithelial
 Connective
 Muscle
 Nervous

Cells, Tissues and Organs
Epithelial Tissue


Covers body surfaces and lines body cavities
Three types:
 Squamous
epithelium comprised of flattened
cells
 Cuboidal epithelium is made up of cube-shaped
cells
 Columnar epithelium consists of elongated cells
Squamous Epithelial Cells
Squamous cells have the appearance of
thin, flat plates
 Have horizontally flattened, elliptical
nuclei because of the thin flattened form
of the cell
 Form the lining of cavities such as the
mouth, blood vessels, heart and lungs
and make up the outer layers of the skin

Squamous Epithelial Cells
Squamous Epithelial Cells
Cuboidal Epithelial Cells
Cuboidal cells are roughly square or
cuboidal in shape
 Each cell has a spherical nucleus in the
center
 Found in glands and in the lining of the
kidney tubules

Cuboidal Epithelial Cells
Cuboidal Epithelial Cells
Columnar Epithelial Cells
Cells are elongated and column-shaped
 Nuclei are elongated and are usually
located near the base of the cells
 Columnar epithelium forms the lining of
the stomach and intestines
 Some columnar cells are specialized for
sensory reception such as in the nose,
ears and the taste buds of the tongue

Columnar Epithelial Cells
Columnar Epithelial Cells
Epithelial Tissue

Simple epithelium
made up of only
one cell layer

Stratified
epithelium has
more than a single
layer of cells
Simple (Squamous)
Simple (Squamous)
Stratified (Squamous)
Functions of Epithelial Tissue
Movement of materials into, out of, or
around the body
 Protection of the internal environment
against the external environment
 Secretion of a product

Examples of Epithelial
Tissues

Glands:
 Intestinal
goblet cells (single epithelial cells)
 Endocrine glands (multicellular)


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Many animals have skin that is composed of
epithelium
Vertebrates have keratin in their epithelial cells
to reduce water loss
Many invertebrates secrete mucus or other
materials from their skin (earthworms)
Connective Tissue
Serve many purposes in the body including:
 Support
 Protection
 Binding
 Blood formation
 Fat storage
 Fill space
Connective Tissue
Cells are separated from one another by a
non-cellular matrix
 This matrix may be:

 Solid
as in bone
 Soft as in loose connective tissue
 Liquid as in blood
Types of Connective Tissue

There are 3 main types of connective
tissue
Loose Connective Tissue
Fibrous Connective Tissue
Specialized Connective Tissues
 Adipose Tissue (Fat)
 Cartilage
 Bone
 Blood
Loose Connective Tissue
(LCT)
Fibroblasts are separated by a collagen
fiber-containing matrix
 Collagen provides elasticity and
flexibility
 Occurs beneath epithelium in skin and
many internal organs
 Forms a protective layer over muscle,
nerves and blood vessels

Fibrous Connective Tissue
(FCT)
Consists of many collagen fibers closely
packed together
 Occurs in tendons, connecting muscle to
bone
 Make up ligaments, connecting bone-tobone at a joint

Specialized Connective Tissue: Fat
Cartilage
Soft
 Structural proteins deposited in the matrix
between cells
 Forms embryonic skeletons
 Occurs in mature human adults in ears,
joints and tip of nose

Cartilage
Bone






Hard
Calcium salts deposited in matrix
Serve as a sink for calcium
Proteins provide elasticity while minerals provide
strength
Dense bone has osteocytes located in lacunae
(Haversian canals)
Spongy bone occurs at the end of bones and
absorb stress
Bone
Blood





Connective tissue separated by a liquid matrix
called plasma
Red blood cells (erythrocytes) carry oxygen
White blood cells (leukocytes) function in the
immune system
Platelets are cell fragments important in blood
clotting
Plasma transports glucose, wastes, CO2,
hormones and regulate water balance for the
blood
Blood
Blood
Muscle Tissue
Facilitates movement by contraction of
individual muscle cells referred to as
muscle fibers
 Found only in members of the animal
kingdom
 Three types:

 Skeletal
 Smooth
 Cardiac
(Striated)
Muscle Fibers




Multinucleated with nuclei just beneath the
plasma membrane
Prominent striated, thread-like myofibrils
The fundamental unit of the muscle is the
sarcomere
Each sarcomere consists of:
 Thick filaments made of myosin at the center
 Thin filaments made of actin attached to the
Z line
Muscle
Skeletal Muscle
Function in conjunction with the skeletal
system in voluntary muscle movement
 Striated with alternating bands at right
angles to the long axis of the cell
 The bands are areas of actin and myosin
deposition

Skeletal Muscle
Smooth Muscle
Lack banding
 Spindle shaped cells that form masses
 Function in involuntary movements
and/or autonomic responses like
breathing, secretion, etc.
 Make up structures in the digestive
system, reproductive tract and blood
vessels

Smooth Muscle
Cardiac Muscle
Striated
 Limited to the heart
 Cells are forked, with nucleus near the
center
 Cells are connected together by disks

 Intercalated
disks
Cardiac Muscle
Nervous Tissue
Important in the integration of stimulus
and control of the response to that
stimulus
 Made of nerve cells called neurons and
glial cells (helper cells)

 Neurons
transmit nerve messages
 Glial cells are in direct contact with neurons
and often surround them
Nervous Tissue
The neuron is the functional unit of the
nervous system
 Variable in size and shape
 Humans have about 100,000,000,000
(100 billion) neurons in their brain! Wow!

Neuron
Nervous Tissue
Each neuron has a cell body, an axon
and many dendrites
 The cell body contains the nucleus,
mitochondria and other organelles
 The axon conducts messages away from
the cell body
 Dendrites receive information from other
cells and direct them to the cell body

Neuron Structure