Unit V Anatomy and Physiology of Plants and Animals Learning Goal 2 Explain the function of structures involved in protection, support, and movement of plants, animals and humans.

Plants Protection Dermal tissue in plants is the outermost protective layer. It consists of epidermal cells that are generally unspecialized except for those that form guard cells surrounding the stoma, and trichomes. Trichomes are tiny outgrowths of epidermal cells that may give leaves a hairy appearance. They may exude sugars, toxins. Trichomes from root epidermal cells are known as root hairs, and help plants absorb water.

Support Ground Tissue – Makes up most of the plant body and functions in metabolism, storage and support. There are 3 types: Parenchyma – makes up the bulk of soft tissues in plants. Surrounded by air spaces especially in leaves to facilitate movement of gases.

Collenchyma This tissue provides flexible support to help strengthen plant parts that are still growing. Cells are typically elongated and collenchyma tissue appears “stringy”.

Sclerenchyma This tissue provides rigid support and protection to plants. Cells have thick secondary walls containing lignin and perforations through which water can pass. Mature cells die as they are encased in lignin, but continue to provide support for the plant.

Movement Plants don’t move independently from place to place but can bend in response to environmental stimuli such as light (phototropism) or touch (thigmotropism) This occurs due to the presence of hormones called auxins which stimulate cell elongation on the shaded side of the stem.

Animals Protection Epithelial tissues cover body surfaces and the surfaces of internal organs, as well as line cavities and ducts within the animal body. They provide protection from invasion by bacteria and viruses and secrete and absorb substances.

Classifications of Epithelial Tissue: Simple or stratified, meaning single or multi- layered. Squamous – flattened cells Cuboidal – roughly shaped like cubes Columnar - elongated

Support Skeletal Systems: Hydrostatic Skeletons- consist of muscles and fluid that provide support for the animal with no rigid support from tissue like bone. Found in many invertebrates like worms, and cnidarians.

Exoskeletons A rigid external body covering that provides support and protection. May be made of hard calcium carbonate such as in mollusks or chitin as in arthropods.

Endoskeletons Consist of internal body structures made of bone or cartilage and protection in some invertebrates and all vertebrates.

Movement Muscle tissue provides all animals with the ability to move around independently. Muscle cells can contract or shorten due to the interaction of two proteins, actin and myosin. There are three types of muscle tissue, skeletal, cardiac, and smooth which produce movement in vertebrates.

Skeletal Muscle Also called muscle fibers, are attached by tendons to the skeleton. They contain many nuclei and are packed with actin and myosin molecules.

Cardiac Muscle This is the contractile tissue of the heart. It has a striated appearance because it contains actin and myosin molecules arranged in a similar manner to skeletal muscle. They form an interlinked network that makes heart muscle contract in all directions, producing a squeezing or pumping action.

Smooth Muscle Found in the walls and tubes of cavities in the body. Contractions of smooth muscle move and mix the stomach and intestinal contents, constrict blood vessels, and push the infant out of the uterus during childbirth.

Patterns of Movement in Vertebrates Fishes and snakes have muscle blocks located on either side of backbone that give them a side-to-side movement for forward motion.

Amphibians and reptiles have limbs on sides in a “push-up position” causing them to walk in a side-to-side motion.

Mammals have limbs straight under them giving them more of an up and down motion when they walk.