Architectural pattern of an animal

Architectural Pattern of an

Animal

Levels of Organization in Organismal Complexity

Protoplasmic grade of organization. Found in unicellular organisms. All life functions are confined within the boundaries ofa single cell. Within the cell, protoplasm is differentiated into organelles capable ofperforming specialized functions.

Cellular grade of organization. Aggregation of cells that are functionally differentiated. Such cells have little tendency tobecome organized into. Some flagellates, such as Volvox, that have distinct somatic andreproductive cells might be placed at the cellular level of organization.

Cell-tissue grade of organization. A step beyond the preceding is the aggregation of similar cells into definite patterns orlayers, thus becoming a tissue. The jellyfishes and their relatives (Cnidaria) more clearlydemonstrate the tissue plan. An excellent example of a tissue in cnidarians is the nerve net,in which nerve cells and their processes form a definite tissue structure, with the function ofcoordination.

Levels of Organization in Organismal Complexity

Tissue-organ grade of organization. Organs are usually composed of more than one kind of tissue and have a more specialized function than tissues. The first appearance of this level is in flatworms (Platyhelminthes), in which there are well-defined organs such as eyespots, proboscis, and reproductive organs. In fact, the reproductive organs are well organized into a reproductive system.

Organ-system grade of organization.When organs work together to perform some function, we have the highest level of organization—the organ system. Systems are associated with the basic body functions—circulation, respiration, digestion, and the others. Most animal phyla demonstrate this type of organization.

A tissue is a group of similar cells(together with associated cellproducts) specialized for theperformance of a common function.

Types of Tissues

The study of tissues is called histology.

During embryonic development, thegerm layers become differentiatedinto four kinds of tissues. These areepithelial, connective, muscular,and nervous tissues.

Epithelial Tissue

An epithelium (pl., epithelia) is a sheet of cells that covers an external or internal surface.Outside the body, the epithelium forms a protective covering. Inside, the epithelium linesall organs of the body cavity, as well as ducts and passageways through which variousmaterials and secretions move. On many surfaces epithelial cells are modified into glandsthat produce lubricating mucus or specialized products such as hormones or enzymes.

Functions:

-Cover external body surfaces and cavities, and line other internal body cavities.- form necessary portions of glands- forms a protective covering of all body surfaces against mechanical injury and lossof water.- may be modified to carry out special functions of absorption, secretion, excretion,sensation and respiration.

All types of epithelia are supported by an underlying basement membrane,which is a condensation of the ground substance of connective tissue.

Epithelial Tissue

Classifications:

Simple epithelium

Made up of only one layers, and are found in all metazoan animals.

Stratified epithelium

Made up of two or more layers of the cell, and are mostly restricted to vertebrates

Combination of several shapes of cells

Connective tissues are a diverse group of tissues that serve various binding andsupportive functions. They are so widespread in the body. It is composed ofrelatively few cells, many extracellular fibers, and a ground substance (also calledmatrix), in which the fibers are embedded.

Connective Tissue

Classifications:

-Connective Tissue Proper- Cartilage- Bone (Osseous Tissue)- Blood (Vascular Tissue)

Connective Tissue Proper

Fibers form the main bulk of the tissue embedded within the matrix.

3 kinds of intercellular fiber

-Collagenous fibers – colorless, fine & flexible protein fibers lying parallel forming bundles- Elastic fibers – fibrillar branched & elastic protein fibers forming irregular network.- Reticular fibers – extremely fine & highly branched forming networks

-Collagenous and reticular fibers maysimply be diff. morph. expressions of asingle fibrous protein.

Made up of highly elastic fibers w/ fewscattered thin collagen fibers. This tissue fillsthe space between organs & serves aspacking materials surrounding elements ofother tissues. Binds muscle cells together &binds skin to underlying tissues.

2 Kinds of Connective Tissue Proper

Loose Connective Tissue Dense Connective Tissue

Made up of thick collagen fibers and dark,compressed cells between the fiber bundles.This tissue occurs in tendons, ligaments, dermisof the skin, and submucous layer of the intestineand urinary tract.

- not covered by perichondrium found in intervertebral discs, symphysis pubis, and in mandibular joints

Cartilage

Elastic cartilageHyaline cartilage

Made up of cartilage cells, chondrocytes, lodged in cavities or spaces called lacunaescattered irregularly in the matrix that appears transparent and homogenous but composedof dense collagen fibers and elastic fibers embedded in a rubbery ground substance. It isproduced by the chondroblast in a process called chondrification.

3 types of cartilage

-Covered by a fibrous layer, perichondrium- found in nose, larynx, trachea, bronchi, ends of ribs, surfaces of bones w/in cavities

- yellow in color, greater flexibility and elasticity due to prominince of elastic fibers.- enveloped by perichondrium found in external ear, eustachiantube & epiglottis

Fibrocartilage

Cartilage facilitate movements of joints, provide flexibility and support

Bone (Osseous) Tissue

A hard specialized connective tissue w/ its collagenous matrix impregnated w/ mineral saltdeposits, including calcium and phosphorus. Consists of cells called osteocytes & maskedcollagenous fibers embedded in a matrix containing ostein. Derived from ossein, bonecollagen. Fibrous CT covering the bone is periosteum, while endosteum lines the bonemarrow cavity. Bone is produced by osteoblast in a process called ossification. Functionsfor support, protection, assisting for movement and storage of minerals.

Classification according to shape

Long bone

Composed of middle portion, the diaphysis orshaft, and the epiphysis or ends of the bone.Bones of legs and arm.

Flat bone

Lacks a bone marrow. Bones of skull andscapula.

Irregular bone

Neither long nor flat & also lacks bonemarrow. Bones of wrist and ankle.

Bone (Osseous) Tissue

Lamellae

Series of concentric rings/circles arround acentral Haversian canal

Lacunae

Small spaces in between the Lamellae w/ccontain the osteocytes.

Osteocytes

Bone cells

Canaliculi

Minute channels that linked lacunae togetherw/c provides routes by w/c nutrients cannutrients can reach the osteocytes & removal ofwaste materials

Haversian canals

Central tubes w/c containblood vessels and nerves

Bone marrow

Responsible for production of blood cellsand storage of chemical energy.

Blood (Vascular) Tissue

Consists of cells, matrix, and fibers. Functions in transporting gases, nutrients, hormones, enzymes and other substances to and from different parts of the body; in blood clotting; defense of the body; regulating body fluid electrolytes; in controlling pH (7.4); & in maintaining body temperature.

Components of the blood

Red Blood Cells (Erythrocytes)

Most numerous. Disc shape containing large amounts of hemoglobin. Tend to adhere one another by thin flat or broad surfaces and form rows resembling piles of coins known as Ruoleaux formation.

White Blood Cells (Leucocytes)

Generally bigger, nucleated, w/out hemoglobin, fewer in number w/c originates from bone marrow, spleen, & lymphatic tissues. Do not exhibit Ruoleaux formation. Functions in body defense against microorganisms by their phagocytic action & antibody production

Granulated (granulocyte)

w/ granules on cytoplasm & w/ 1 or more nucleus-Eosinophil – two lobed nucleus-Basophil – S-shaped nucleus-Neutrophil – w/ 3 or 4 nuclei

Agranulated (agranulocyte)

w/out granules on cytoplasm & with only 1 nuclei-Lymphocyte – the smallest; produces antibody- Monocyte – mono-nucleated cell; transformed into macrophage

Blood (Vascular) Tissue

Components of the blood

Platelets (Thrombocytes)

Small, non-nucleated, colorless, round/ovel biconcave corpuscle produced by agiant cell called megakaryocyte found in bone marrow. Plays vital role in bloodclotting.

Plasma

Liquid component of blood (90% water) w/c contains numerous cells, organic& inorganic salts, hormones, nitrogenous wastes and other substances likeprothrombin and fibrinogen, and antibodies against infection.

Hemoglobin

Protein constituent of the blood responsible for the attachment of oxygen andfor the red coloring of the blood.

Hemostasis: Prevention of Blood Loss

Muscular Tissue

Responsible for body’s movement, heat production, and posture maintenance. Displays excitability, contractility in response to stimulation due to the presence of numerous fine fibers, myofibrils.

Muscle fibers

Consist of myofibrils, composed chemically of a protein called actomyosin. Each myofibrilis made up of alternating myofilaments, the thin actin and the thick myosin filaments.Myofibril exhibits alternate anisotropic (A) & isotropic (I) striations. A relaxed myofibrilhas A and I bands approximately of equal width. The I band transverse at the middle by athin zigzag line, Z disk (darker zone), while A band is transversed by a thin M-line & H-zone(central light area). The segment between the two Z-disks represents sarcomere,functional unit of muscle contraction. Contraction of muscle is the result of the sliding oftwo sets of myofilaments w/ respect to each other, wherein A band remains constant but Iband shortens. With relaxation, the original arrangement of disks returns.

Muscular Tissue

Classification

Muscular Tissue

Consist of long, cylindrical muscle fibers w/crossbanded or striated appearance. Foundattached to skeleton, voluntary in actionbecause movement is the result of impulses.

Skeletal Muscle

Cardiac Muscle

Striated, branched muscle fibers (Y-shaped),has single central nucleus. Multifibers areattached by intercalated discs. Formed bymyocardium (middle, thicker layer).Involuntary.

Classification

Muscular Tissue

Consist of spindle shaped cells w/c are thickened at the middle but tapered towards theends. An oval or rod-shaped nucleus occupies in the central, thickest portion of the cellbody. Consist of unstriated muscle. Capable of peristalsis, contractions on the walls of thedigestive tract. Involuntary in action.

Visceral/Smooth Muscle

Nervous Tissue

Specialized for conduction of nerve impulses.Consists of 2 specialized elements, neurons, w/c isthe functional/structural units capable of receiving &conducting impulses; neuroglia, composed of glialcells & fibers, w/c serve support & bind together thecomponent nervous elements.

Cell body (Cyton)

Composed of central nucleus w/in the protoplasmicfluid called neuroplasm.

Cell processes

Cytoplasmic extensions that continue for aconsiderable length from the cell body.

Dendrite/Dendron

One or more process; Short; carries impulsestowards cell body

Axon/axis cylinder

Single process; Long; do not branch near cell body.Conveys impulses away from cell body

Nervous Tissue

During the nerve impulse transmission, association ofprocesses of two nuerons forms a synapse (junctionbetween two successive neurons). Dendrites of one neuron,associated through synapse with axon endings offunctionally related neurons, receive the nerve impulse fromanother neuron. Neurons are sensitive to different types ofstimuli s.a temperature, pressure, light, etc. These nerve cellstransmit electrical nerve impulses thereby movinginformation around the body.

Nervous tissue is specialized for reception of stimuli andconduction of impulses from one region to another. Two basictypes of cells in nervous tissue are neurons (nerve), the basicfunctional unit of the nervous system, and neuroglia, a variety ofnon-nervous cells that insulate neuron membranes and servevarious supportive functions.

Type of Neurons according to function

Sensory (Afferent Neuron)conducts impulses towards CNS

Motor (Efferent neuron)conducts impulses away from the CNS

Association (Interneuron)conducts impulses w/in CNS

Type of Neurons according number of cell processes

Myelin sheath

Covers axon of a neuron

Animal Body Plans

Animal Symmetry

Symmetry refers to balanced proportions, or correspondence in size and shape of parts on opposite sides of a median plane.

Spherical symmetry means that anyplane passing through the centerdivides the body into equivalent, ormirrored, halves.

This type of symmetry is found chieflyamong some unicellular forms and israre in animals. Spherical forms arebest suited for floating and rolling.

Radial symmetry applies to forms that can be divided into similar halves by more thantwo planes passing through the longitudinal axis. These are tubular, vase, or bowl shapesfound in some sponges and in hydras, jellyfish, sea urchins, and related groups, in whichone end of the longitudinal axis is usually the mouth.

The two phyla that are primarily radial,Cnidaria and Ctenophora, are called theRadiata.

Animal Symmetry

Echinoderms (sea stars and their kin) areprimarily bilateral animals (their larvae arebilateral) that have become secondarilyradial as adults.

Bilateral symmetry applies to animals that can be divided along a sagittal plane into twomirrored portions— right and left halves.

Animal Symmetry

The appearance of bilateral symmetry in animal evolution was a major advancement,because bilateral animals are much better fitted for directional (forward) movementthan are radially symmetrical animals.

Bilateral animals form a monophyletic groupcalled the Bilateria. Bilateral symmetry isstrongly associated with cephalization.

Animal Symmetry

Invertebrates pectoral refers to the chestregion or the area supported by theforelegs, and pelvic refers to the hip regionor the area supported by the hind legs.

Terms used for locating regions of bilaterally-symmetrical animals:

anterior, used to designate the head end

posterior, the opposite or tail end

ventral, the front or belly side

Medial refers to the midline of the body

dorsal, the back side

lateral, to the sides

Distal parts are far from the middle of the body

proximal parts are nearer

frontal plane (coronal plane) divides a bilateralbody into dorsal and ventral halves.

Sagittal plane the plane dividing an animal intoright and left halves

transverse plane (cross section) would cutthrough a dorsoventral and a right-leftaxis at right angles to both the sagittaland frontal planes and would result inanterior and posterior portions.

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