Grades of Organizationa and Animal Body Plans

GRADES OF ORGANIZATION AND ANIMAL BODY PLANS ● Usually recognized as five (5) major grades of organizations 1. Protoplasmic - Confined amongst unicellular organisms - A type of organization where all life functions are confined within the boundaries of a single cell - Fundamental unit of life - Protoplasm is differentiated into organelles within a cell and are capable of performing specialized functions - Has a ciliate known as paramecium 2. Cellular - An aggregation of cells that are functionally differentiated - Division of labor—cells concerned with reproduction and cells concerned with nutrition - Flagellates examples: ● Volvox Species ○ have distinct somatic and reproductive cells ○ Placed at the cellular grade or level organization 2. Radial Symmetry - Applies to forms that can be divided into similar halves but with more than two planes passing through the longitudinal axis - The shapes of animals are often tubular, vase-like, or bowl-shaped - Can be placed amongst sponges and hydra, jellyfish, urchins, and other groups 3. Bilateral Symmetry - Applies to animals that can be divided along a sagittal plane into two (2) portions (right and left halves) - Its appearance is considered to be a major innovation as these animals are better fitted for directional or forward movement than radially symmetrical animals - Often associated with cephalization (differentiation of the head; the connection of nervous tissues) - Since organs in the head bestows obvious advantages to an animal moving through its environment head first - Produces an efficient position of organs for sensing the environment and likewise the response of the organism (stimuli) 3. Cell-Tissue - An aggregation of similar cells into definite patterns or layers - Organized to perform a common function to form a tissue - Sponges or poriferans are considered (by some authorities) to belong in this grade - Jellyfish and cnidarians demonstrate the tissue plant - Both groups (sponges and cnidarians) are largely of this cellular grade of organization, as most cells are often not organized into tissues - Example among cnidarians: ● Nerve Net ○ Nerve cells and their processes form a definite tissue structure with the function of coordination 4. Tissue-Organ - Aggregation of tissue into organs - A step further into complexity - Usually composed of more than one kind of tissue - Have specialized functions than that of a tissue - The organizational level of platforms or those from the phylum platyhelminthes in which well-defined organs like eye spots, the proboscis, and other reproductive structures and organs are present - Amongst flatworms, the reproductive organs transcend tissue organ grade and are organized into the reproductive system REMEMBER ● Protostomes = blastopore becomes mouth ● Deuterostomes = blastopore becomes anus ● Diploblastic = two germ layers ● Triploblastic = + mesoderm 5. Organ - Organs work together to perform a function, producing the highest level of organization—-the organ system - Systems are associated with body functions such as circulation, respiration, reproduction, and digestion - Most animal phyla demonstrate this type of organization BODY SYMMETRY ● Refers to balanced proportions or correspondence in size and, likewise, shape of parts and opposite sides of a median plane ● There are three (3) types of symmetry 1. Spherical Symmetry - Any okane passing through the center that divides a body into equivalent or mirrored halves - Occurs amongst unicellular forms or eukaryotes and is rare among vertibrates or higher animals - Best suited for floating and, likewise, rolling METHODS OF MESODERM FORMATION ● Will dictate the type of body cavity present in a certain animal DEVELOPMENT SEQUENCE OF ANIMALS SIMPLE EPITHELIA ● A single layer of cells ● Occurs mainly in all metazoans ● Classified based on shape and function a. Squamous - has a presence of flattened cells forming a continuous lining of capillaries, lungs, and surfaces allowing diffusion and transport SEGMENTATION ● Metamirism (segmentation) is a common feature of metazoans ○ Serial repetition of body segments along the longitudinal axis of the body ● Metamere or somite - contains internal and external structures ○ Mobility and complexity of structure and function ○ Ex. earthworm (phylum amelida) ● Metamirism is clearly represented through the segmental arrangement that includes external and internal structure of several systems ● Segmentation permits great body mobility and complexity of structure and function ● Potential is amply displayed in phylum anthropoda (largest assemblage of animals on earth) ● Occurs amongst cordates in addition to those from the phylum anelida and likewise anthropoda b. Cuboidal - short boxeed like cells lining the ducts and tubials, kidneys, salivary glands, and other excretory systems c. Columnar - taller than cuboidla with elongated nuclei and used mainly for increased absorption along the intestines VERTIBRATE TISSUE TYPES ● Is a group of similar cells specialized for performance of a common function ● The study of tissus is called histology or microanatomy ● All cells in the metazoan animals tend to form tissues (sometimes cells of a tissue may be of several kinds and some tissues may have much extra cellular material) ● During the embryonic development, the germ layers com differentiated into four (4) types of tissue: 1. Epithelial Tissue - Epithelium is a sheet of cells that covers an internal or external part of the animal body ● Internally , lining for all organs and ducts as well as all passageways ○ Allows transport of secretions ○ Mucus and specialized hormones and enzymes ● Externally, used for protection ○ Epithelial cells are classified based on form and number of layers ■ Simple ■ stratified STRATIFIED EPITHELIAL TISSUE ● A type of tissue wherein it has or bears two (2) or more cell layers and are mostly restricted to vertibrates ● Is adapted to withstand mechanical abrasion, distortion ● Lines the oral cavity, esophagus, anal canal, and skin ● Separated from underlying tissues from the presence of the basal layer that continues to divide and produce new cells ● There is a presence of keratinized skin cells mainly found on the upper surface in terms of animals ○ Example ■ Reptiles, birds, mammals ● These skins/tissues are mostly stratified squamous TRANSITIONAL EPITHELIAL TISSUE ● Type of stratified epithelium specialized for great stretching ● Are mainly found in the urinary tract and the bladder of vertibrates ● Allow enlargement while storing waste ● When stretched it appears to have only a few layers of extremely flattened cells CARTILAGE AND BONE ● Cartilage is semi-rigid tissue of firm matrix cells (chonorocytes) with collagen and elastin ○ Lacks blood supply so nutritients and waste have to diffuse through the ground substance such that it heals very slowly after damage ● Bone is the strongest connective tissue made of calcified matrix (osteocytes) around collage fibers ○ Blood vessels flow through tiny channels called canaliculi and large canals that allow for continuous repair called remolding CONNECTIVE TISSUE ● Connective tissue is widespread in body but contains relatively few cells, many fibers, and a ground substance or matrix that suspends fibers ● Two types of connective tissue proper occur in vertibrates ○ Loose connectivity ○ Dense connective tissue ● Other specialized connective tissues include blood, lymph, aadipose tissue, cartilage, and bone LOOSE CONNECTIVE TISSUE ● Also known as the areolar connective tissue ● Seves as a packing materials ● Anchors blood vessels, nerves, and organs DEVELOPMENT SEQUENCE OF ANIMALS ● Consists mainly of fibroblast that synthesize fibers, ground substance, and wandering macrophages that destroy pathogens and damaged cells ● Considered as the most abundant tissue in animals ● Originates mainly from the mesoderm ● There are mainly two types of muscle cells 1. Striated - a transversely striped muscle (skeletal, cardiac) a. Skeletal - Mainly long cylindrical fibers - Multinucleated - Considered to be as voluntary muscle in vertibrates or amongst vertibrates DENSE CONNECTIVE TISSUE ● Forms tendons, ligaments, and fascia ○ Fascia is arranged in sheats where spans of tissues surround the skeletal muscle b. Cardiac muscle - Short branch networks - Uninucleated - Connected by interconnected discs - Considered to be as involuntary muscle 2. Smooth - Non-striped - They are long tapering and unprimed with the presence of a central nucleus - Control is involuntary NEURON SRUCTURE ● It is specialized ● Receives stimuli ● Conducts impulses fromnone region to another ● Common parts of a neuron 1. Soma - nucleated body 2. Dendrites - they receive signals from receptors 3. Axon - carries signal away from the nerve body 4. Myelin sheath - Aka insulating sheath - Increases speed of signals during transmission 5. Synapse - specialized junctions between each neuron or effector organs