Chapter 9 Architectural Patterns of An Animal Zoology Chapter 9 Architectural Patterns of An Animal

Five Major Grades of Organization 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

Metazoa- multicellular 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

Tissue- group 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 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 Sagittal Plane- divided into right and left Transverse Plane- divided into anterior and posterior

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. Pseudocoleomate-false coelom with mesodermal cells that line outer blastocoel edge and leaves two body cavities. The mesoderm only partially surrounds it.

Mesoderm Formation 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 Layers- determine body plans Diploblastic-two germ layers Triploblstic-three germ layers Blind gut-incomplete gut, food and waste enter and leave through same opening Complete gut-one way flow of food from mouth to anus, complex tube within a tube 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 Body Fluids- located in intracellular space and extracellular space Extracellular structural elements-supportive material of organism: loose connective tissue, cartilage, cuticle, provide mechanical stability and protection

Cellular Components- tissue 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 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.

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.