Lecture 11 BIO 311D 1st Edition Outline of Last Lecture I Cell Structure and Specialization II Reproduction and Development III Body Plans IV Tissues V Protostome and Deuterostome Developments Outline of Current Lecture I Evolution of Animal Size and Shape II Hierarchical Organization of Body Plans III Tissues a Epithelial b Connective c Muscle d Nervous Current Lecture Which statement is true A Cells organized into tissues B B Tissues are organized into organs C Organs are organized into organ systems D All of the above are true E None of the above are true Evolution of Animal Size and Shape Physical laws constrain strength diffusion movement and heat exchange As animals increase in size their skeletons must be proportionately larger to support their mass Evolutionary convergence reflects different species adaptations to a similar environmental challenge A single celled protist living in water has a sufficient surface area of plasma membrane to service its entire volume of cytoplasm Multicellular organisms with a saclike body plan have body walls that are only two cells thick facilitating diffusion of materials Pressure changes diffusion and a very complex system that increases surface area to volume ratio helps multicellular organisms reach the desired nutrients essential for survival In flat animals such as tapeworms the distance between cells and the environment is minimized More complex organisms have highly folded internal surfaces for exchanging materials In vertebrates the space between cells is filled with interstitial fluid which allows for the movement of material into and out of cells A complex body plan helps an animal living in a variable environment to maintain a relatively stable internal environment Hierarchical Organization of Body Plans Tissues Specialized cells are organized into tissues that have different functions What are the four types of tissues A Muscle immune endocrine nervous B Nervous connective epithelial skeletal C Connective muscle epithelial nervous D Epithelial connective muscle immune Tissues are classified into four main categories o Epithelial Main function is for protection Covers the outside of the body and lines the organs and catities within the body Contains cells that are closely joined The shape of epithelial cells may be cuboidal dice columnar bricks or squamous like floor tiles Epithelial cells may be Single layered simple Multiple tiers of cells stratified A single layered of cells varying in length pseudostratified o Connective Mainly binds and supports other tissues Contains sparsely packed cells scattered throughout an extracellular matrix Matrix consists of fibers in a liquid jellylike or solid foundation There are three types of connective tissue fiber all made of protein Collagenous fibers provide strength and flexibility Elastic fibers stretch and snap back to their original length Reticular fibers join connective tissue to adjacent tissues Connective tissue contains cells including Fibroblasts that secrete the protein of extracellular fibers Macrophages that are involved in the immune system In vertebrates the fibers and foundation combine to form six major types of connective tissue Loose connective tissue binds epithelia to underlying tissues and holds organs in place Cartilage is a strong and flexible support material Fibrous connective tissue is found in tendons which attach muscles to bones and ligaments which connect bones at joints Adipose tissue stores fat for insulation and fuel Blood is composed of blood cells and cell fragments in blood plasma Bone is mineralized and forms the skeleton o Muscle Most abundant of all tissues Consists of long cells called muscle fibers which contract in response to nerve signals Can be voluntarily controlled or involuntary controlled It is divided in the vertebrate body into three types Skeletal muscle or striated muscle is responsible for voluntary movement o Striated and voluntarily controlled Smooth muscle is responsible for involuntary body activities o Not striated and involuntarily controlled Cardiac muscle is responsible for contraction of the heart o Striated and not voluntarily controlled o Nervous Nervous tissue senses stimuli and transmits signals throughout the animal Nervous tissue contains Neurons or nerve cells that transmit nerve impulses Glial cells or glia that help nourish insulate and replenish neurons Organs made of tissues some organs belong to more than one organ system Organ system made of organs Hormones are A Fast acting with long lasting effects B Relatively slow acting but can have long lasting effects C Fast acting with effects that are quickly diminished D Relatively slow acting with effects that are quickly diminished Coordination and Control Only some cells can receive hormones because only some organs have receptors for hormones Hormones are sent through the blood stream Control and coordination within a body depend on the endocrine system and the nervous system The endocrine system transmits chemical signals called hormones to receptive cells throughout the body via blood A hormone may affect one or more regions throughout the body Hormones are relatively slow acting but can have long lasting effects The nervous system transmits information between specific locations The information conveyed depends on a signal s pathway not the type of signal Nerve signal transmission is very fast Nerve impulses can be received by neurons muscle cells endocrine cells and exocrine cells Animals manage their internal environment by regulating or conforming to the external environment A regulator uses internal control mechanisms to moderate internal change in the face of external environmental fluctuation A conformer allows its internal condition to vary with certain external changes Animals may regulate some environmental variables while conforming to others Homeostasis Organisms use homeostasis to maintain a steady state or internal balance regardless of external environment In humans body temperature blood pH and glucose concentration are each maintained at a constant level Mechanisms of homeostasis moderate changes in the internal environment For a given variable fluctuations above or below a set point serve as a stimulus these are detected by a sensor and trigger a response The response returns the variable to the set point The dynamic equilibrium of homeostasis is maintained by negative feedback which helps to return a variable to a normal range Most