Tissues, Organ Systems and Homeostasis Dr. A. Russo-Neustadt Biology 155

Organization of the Animal Body Animals’ bodies exhibit hierarchical organization – –Biological molecules are organized into organelles (ex. Phospholipids and proteins are arranged into the plasma membrane) –Organelles are organized into a cell (ex. Nucleus + plasma membrane + cytoplasm proper + many organelles = cell)

Organization of the Animal Body (continued) Hierarchical organization continued – –Groups of similar cells are organized into tissues (ex. Cardiac muscle cells are organized into the tissue, cardiac muscle); Note that the evolution of multicellular living forms required development of tissues –Two or more tissues are organized to form an organ (ex. Cardiac muscle tissue + connective tissue + epithelial tissue = the heart; provides force to move blood)

Organization of the Animal Body (continued) Hierarchical organization continued – –Organs are organized into organ systems (ex. Heart + blood vessels + blood = cardiovascular system; function is transport) –Organ systems are organized into an organism (ex. An animal consists of 11 organ systems)

Embryonic Tissues – all adult tissues are derived from one of three embryonic tissues gut Ectoderm = “outside skin” Endoderm = “inside skin” Mesoderm = “middle skin” Cross section through embryo Animal embryo

Fate of Embryonic Tissues Ectoderm will become the outer covering of the body and the nervous system Mesoderm will become the muscles and internal skeletons Endoderm will become the lining of the gastrointestinal tract, lungs, vessels and ducts

Adult Tissues Definition = groups of cells with similar structure, embryonic origin, and function; cells are bound together by extracellular material and function together to perform a specific task There are four main types of adult tissues in the animal body

Epithelial Tissues Source = may be derived from any tissue in the embryo Function = mainly protective, therefore they cover all free surfaces of the body; can be specialized for absorption, excretion, secretion, etc.

Epithelial Tissues (continued) Characteristics = –Closely joined cells with little extracellular material between the cells –Presence of a basement membrane secreted by the epithelial cells; separates the epithelial cells from underlying tissues –One free surface not in contact with other cells

Fig. 20.4

Epithelial Tissues (continued) Classification = ask and answer two questions –How many cell layers above the basement membrane? Simple = one layer of cells; used for exchange (ex. Diffusion of gases in the alveoli of the lungs, absorption in the small intestine; see previous slide) Stratified = more than one layer of cells; used for protection (ex. the outer layer of the skin)

Epithelial Tissues (continued) Classification continued – –What shape are the cells? (when viewed from the side) Flat and thin = squamous; used to maximize diffusion (non- energy requiring exchange where things move from an area of high to an area of low concentration); ex. Alveoli of lungs, capillaries Look like squares = cuboidal; used to maximize energy requiring exchange such as absorption and excretion (things can move from an area of low concentration to an area of high concentration); ex. respiratory system Tall and thin = columnar; as cuboidal above; ex. Small intestine

Fig. 20.4

Connective Tissues Source = may be derived from any tissue in the embryo Function = many, but generally holds things together in the body; can be specialized to give structure to and protect body parts

Connective Tissues (continued) Characteristics = –Few cells –Lots of extracellular material between the cells; extracellular material is produced by the cells and is called matrix –Matrix consists of – Protein fibers Ground substance = non-fibrous proteins + other molecules Fluid

Fig. 20.5

Connective Tissues (continued) Classification = ask and answer one question –What is the nature of the extracellular matrix? Fluid = tissue is blood, functions in gas transport

(Matrix)

Connective Tissues (continued) Classification = ask and answer one question –What is the nature of the extracellular matrix? (continued) Solid = –Mainly protein fibers = connective tissue proper (ex. Loose and dense connective tissues, adipose) –Protein fibers + ground substance = special connective tissues (ex. Bone and cartilage)

Fig. 20.5

Muscle Tissues Source = derived from the embryonic mesoderm Function = allows movement of the body or movement within the body Characteristics = –Closely joined cells with little extracellular material –Contain specialized protein fibers capable of contraction

Fig. 20.6

Muscle Tissue (continued) Classification – –Cardiac Muscle = heart muscle One, centrally located nucleus Presence of striations Short, branched cells Presence of intercalated discs “involuntary”

Fig. 20.6

Muscle Tissue (continued) Classification – –Skeletal Muscle Many, peripherally located nuclei Presence of striations long, thin cells “voluntary”

Fig. 20.6

Muscle Tissue (continued) Classification – –Smooth Muscle – found in “hollow organs” One, centrally located nucleus no striations Short, tapered cells “involuntary”

Fig. 20.6

Nervous Tissue Source = derived from the embryonic ectoderm Function = communication Characteristics – –Electrically excitable cells (neurons with cell body and processes), or –Cells that support, nourish and protect the neurons (glia) Classification = none

Fig. 20.7

Animal Organ Systems SystemMajor Component Function IntegumentarySkinExternal Protection SkeletalBonesSupport MuscularSkeletal Muscles Movement Fig

Animal Organ Systems - continued SystemMajor Component Function NervousBrain and Nerves Integration EndocrineEndocrine Glands Integration CirculatoryHeart and Blood Vessels Transport Fig

Animal Organ Systems - continued SystemMajor Component Function RespiratoryLungs or GillsGas Exchange DigestiveGastrointestinal Tract Nutrient Acquisition UrinaryKidneysWaste Elimination Fig

Animal Organ Systems - continued SystemMajor Component Function ReproductiveOvaries and Testes Production of New Individuals ImmuneWhite Blood Cells and Lymph Glands Internal Protection Fig