Animal Form and Function Lecture PDF

Animal Form and Function 1 Diverse Forms, Common Challenges Anatomy is the biological form of an organism. Physiology is the biological function(s) an organism performs. Form and function are closely correlated. Size and shape affect the way an animal int...

Animal Form and Function 1 Diverse Forms, Common Challenges Anatomy is the biological form of an organism. Physiology is the biological function(s) an organism performs. Form and function are closely correlated. Size and shape affect the way an animal interacts with its environment. Which of the following two closely-related animals lives in hot climates? Black-tailed Jackrabbit White-tailed Jackrabbit 2 Divergent and Convergent Evolution Divergent evolution is when two species emerge from the same common ancestor. Convergent evolution often results in unrelated species evolving structures and traits that have the same function. Can you give another example? Fox Dog Bird Bat Butterfly 3 Exchange with the Environment Nutrients, waste products, and Summary Video Link gases must be exchanged across the cell membranes. Rate of exchange is proportional to a cell’s surface area, while amount of exchange material is proportional to a cell’s volume. Surface area and volume increase faster than length as an animal grows. 4 Exchange with the Environment Single-celled organisms in water have sufficient surface area to carry out all necessary exchange. Multicellular organisms with a saclike body plan have body walls that are only two cells thick, facilitating diffusion of materials. Then, why have large, complex body? Large body helps the animal maintain a relatively stable internal environment. 5 Tissues Most animals are composed of cells organized into tissues that have different functions. Tissues consist of a group of structurally and functionally similar cells and their intercellular material. The study of tissue types and functions is histology. 6 Tissue Classification Covered in an earlier lecture Tissues can be classified in many ways: 1. Based on their origin (ectodermal, endodermal, mesodermal) 2. Based on cell composition (epithelial, endothelial, stroma, connective) 3. Based on organ system (e.g., nervous tissue) 4. Based on functions (e.g., needed for growth and repair; used in coordination; used for support and movement, etc.) 7 1. Epithelial Tissue Covers the outside of the body and lines the organs and cavities within the body. It contains cells that are closely joined. The shape of epithelial cells may be cuboidal (like dice), columnar (like bricks on end), or squamous (like floor tiles). The arrangement of epithelial cells may be simple (single cell layer), stratified (multiple tiers of cells), or pseudostratified (a single layer of cells of varying length). 8 2. Connective Tissue Mainly binds and supports other tissues. The matrix consists of fibers in a liquid, jellylike, or solid foundation. Six major types of connective tissue: 1. Loose connective tissue binds epithelia to underlying tissues and holds organs in place. 2. Fibrous connective tissue is found in tendons, which attach muscles to bones, and ligaments, which connect bones at joints. 3. Adipose tissue stores fat for insulation and fuel. 4. Blood is composed of blood cells and cell fragments in blood plasma. 5. Bone is hard and forms the skeleton. 6. Cartilage is a strong and flexible support material. 9 3. Muscle Tissue Responsible for most types of body movement. Muscle cells consist of filaments of the proteins actin and myosin. Three types of muscles in vertebrates: 1. Skeletal muscle is responsible for voluntary movement. 2. Smooth muscle is responsible for involuntary body activities. 3. Cardiac muscle is responsible for contraction of the heart. 10 4. Nervous Tissue Receives, processes, and transmits information (i.e., responds to stimuli). Nervous tissue contains: Neurons, or nerve cells, which transmit nerve impulses. Glial cells, or glia, which support cells. 11 Organ Systems in Mammals 12