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Chapter 9
Architectural Patterns of An Animal
Five Major Grades of Organization
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Unicellular Protozoans
Metazoans
Tissues
Organs
Organ Systems
Unicellular Protozoans
 Simplest eukaryote
 Complete organisms
 All life functions
 Organization of labor
 Distinct support and locomotor devices, fibrils and
sensory structures
Metazoamulticellular animals, greater structural
complexity by combining cells into larger units
 Cells-specialized part of whole organism, not capable
of independent existence
 Cells-specialized for performing various tasks
 Cellular organization-division of labor
Tissuegroup of similar cells
 Perform common functions as a highly organized unit
 Types of tissue-epithelial, connective, nervous
 Special roles of tissue-parenchyma-chief functional
cells, stroma-supportive tissue
Organs
 Made of similar tissues
 Specialized for certain functions
 Carries burden of organ’s chief function
Organ Systems
 Different organs work together
 Eleven different organ systems in metazoans: skeletal,
muscular, integumentary, digestive, respiratory,
circulatory, excretory, nervous, endocrine, immune
and reproductive
Animal Body Plans
 Grade of organization
 Body symmetry
 Number of embryonic germ layers
 Number of body cavities
Symmetry
 Balanced proportions that correspond to size and
shape of parts on opposite sides of median plane.
 Types-spherical, radial, bilateral
Spherical Symmetry
 Plan divides body into
mirrored halves, like in
unicellular organisms
Radial Symmetry
 Divided into similar
halves by more than two
planes passing through
longitudinal axis.
 Biradial-some part is
single or paired with only
2 planes.
Bilateral Symmetry
 Divides along sagittal
plane into two mirrored
portions, right and left
halves, animals are better
fitted for forward
movement-has
cephalization-head,
nervous tissue, sense
organs and mouth
Anatomy Terms
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Anterior-head
Posterior-tail
Dorsal-back
Ventral-belly
Median-midline
Lateral-side
Distal-farther from medial
Proximal –nearer to medial
Pectoral-chest
Pelvic-hip region and hind legs
Body Planes
Frontal Plane- divided
into dorsal and ventral
2. Sagittal Planedivided into right and
left
3. Transverse Planedivided into anterior
and posterior
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Body Cavities-Internal Space
 Metazoans-zygoteblastulagastrula.
 One side of blastula pushes inward and makes a
depression(gastrocoel or archenteron) external
opening is blastopore that becomes the adult mouth,
endoderm is the outer cell layers. Mesoderm is the
third germ layer
Three Methods of Mesoderm
Formation
Acoelomate-mesodermal cells fill blastocoel, gut
only body cavity and parenchyma are the spongy
cells.
2. Pseudocoleomate-false coelom with mesodermal
cells that line outer blastocoel edge and leaves two
body cavities. The mesoderm only partially
surrounds it.
1.
Mesoderm Formation
3. Schizocoelous-mesodermal cells fill blastocoel form
a solid band of tissue around gut and through
programmed cell death space opens inside this band
to form a coelom, ends up with two body cavities:
gut and coelom.
Enterocoleous-cells from gut lining grow outward as
pouches and expand into blastocoel , the pouch walls
form a mesodermal ring, enclose space and becomes
a coelom, pouches close off to enclose coelom
bounded by mesoderm on all sides.
Developmental Layersdetermine
body
plans
1. Diploblastic-two germ layers
2. Triploblstic-three germ layers
3. Blind gut-incomplete gut, food and waste enter and
leave through same opening
4. Complete gut-one way flow of food from mouth to
anus, complex tube within a tube
5. Segmentation(metamerism)serial repetitions of
similar body segments along longitudinal axis of
body, each segment is called a metamere or somite
Metazoan Body Components
Cellular components-derived from three embryonic
germ layers
2. Body Fluids- located in intracellular space and
extracellular space
3. Extracellular structural elements-supportive material
of organism: loose connective tissue, cartilage,
cuticle, provide mechanical stability and protection
1.
Cellular Componentstissue group of similar specialized
cells
Epithelial-sheet of cells that cover an external or
internal surface: lines organs of body cavities, ducts
and passageways, classified by cell form and number
of cell layers
2. Connective-bind, support functions, widespread in
the body, loose connective tissue fibers or dense
fibers made of tendons and ligaments, also includes
cartilage a semi-rigid tissue and bone a calcified
connective tissue.
1.
Cellular Components
3. Muscular-most abundant tissue specialized for
contraction striated, skeletal and cardiac)
4. Nervous-specialized for reception of stimuli and
conduction of impulses from one region to another
made of two cell types neurons the basic functional
unit and neuroglia a variety of nonnervous cells that
insulate neuron membranes and serve support
functions.