Chapter 20 Animal Structure and Function 20 1

Chapter 20 Animal Structure and Function

20. 1 An animal’s form is not the perfect design • The laryngeal nerve of an adult giraffe travels from the brain, makes a U-turn around the aorta in the chest, and then extends back up the neck to muscles in the throat. • Why does the laryngeal nerve make about a 15 -foot journey?

20. 1 An animal’s form is not the perfect design • The surprising length of the laryngeal nerve illustrates a major concept in evolution: Through natural selection, a structure in an ancestral organism can be modified to function in a descendant organism. Explain why the process of natural selection in tetrapods resulted in a long, looped laryngeal nerve instead of a short nerve following a more direct route.

EVOLUTION CONNECTION: An animal’s form reflects natural selection § The body plan or design of an organism – reflects the relationship between form and function, – results from natural selection, and – does not imply a process of conscious invention § For example- streamlined and tapered bodies – increase swimming speeds and – have similarly evolved in fish, sharks, and aquatic birds and mammals, representing convergent evolution.

20. 2 Structure fits function at all levels of organization in the animal body • Anatomy is the study of structure. • Physiology is the study of function. • Animals consist of a hierarchy of levels of organization. • Tissues are integrated groups of _______that perform a common function. • Organs perform a specific task and consist of ________. • Organ systems consist of _________that together perform a vital body function.

20. 3 Tissues are groups of cells with a common structure and function • Tissues are an integrated group of similar cells that perform a common function; they combine to form organs. • Animals have four main categories of tissues: 1. ______________ 2. _____________ 3. _____________ 4. ______________

20. 4 Epithelial tissue • Epithelial tissues, or epithelia, are sheets of closely packed cells that cover body ________ and ____ internal organs and cavities. • Epithelial tissues are named according to the number of cell layers they have and the shape of the cells on their apical surface. • Epithelial cells come in ___ shapes.

20. 5 Connective tissue binds and supports other tissues • Connective tissue -six major types. 1. 2. 3. 4. 5. 6. Loose connective tissue Fibrous connective tissue Adipose tissue Cartilage Bone Blood Why does blood qualify as a type of connective tissue?

20. 6 Muscle tissue functions in movement Muscle tissue is the most abundant tissue in most animals There are three types of vertebrate muscle tissue: 1. ______ muscle causes voluntary movements, 2. ______muscle pumps blood, and 3. ______ muscle moves walls of internal organs, such as the intestines.

20. 7 Nervous tissue forms a communication network • Nervous tissue • senses stimuli and • rapidly transmits information. • Neurons carry signals by conducting electrical impulses. • Other cells in nervous tissue • insulate axons, • nourish neurons, and • regulate the fluid around neurons.

20. 8 Organs are made up of tissues- Each tissue performs specific functions. Explain why a disease that damages connective tissue can impair most of the body’s organs.

20. 9 CONNECTION: Bioengineers are learning to produce organs for transplants • Bioengineers are seeking ways to repair or replace damaged tissues and organs. • New tissues and organs are being grown on a scaffold of connective tissue from donated organs. • Other researchers are using 3 D printers to create layers of cells resembling the structure of organs. Why is a windpipe or a bladder easier to “print” than with a heart?

20. 10 Organ systems work together to perform life’s functions • Each organ system typically • consists of many organs, • has one or more functions, and • works with other organ systems to create a functional organism. Which two organ systems are most directly involved in regulating all other systems?

20. 13 Structural adaptations enhance exchange with the environment- work to maintain homeostasis • Every organism is an open system that must exchange matter and energy with its surroundings. • Cells in small and flat animals can exchange materials ____ with the environment. • Complex animals have ___________ that increase surface area. • Exchange of materials between blood and body cells takes place through the interstitial fluid. How do the structures of the lungs, small intestine, and kidneys relate to the function of exchange with the environment?

What are some ways in which the circulatory system contributes to homeostasis?

20. 14 Animals regulate their internal environment Conditions often fluctuate widely in the external environment, but homeostatic mechanisms regulate internal conditions, resulting in much smaller changes in the animal’s internal environment.

20. 15 Homeostasis depends on negative feedback • Control systems • detect change and • direct responses. • Negative-feedback mechanisms • keep internal variables steady and • permit only small fluctuations around set points.

Animation: Negative Feedback © 2018 Pearson Education, Inc.

Animation: Positive Feedback © 2018 Pearson Education, Inc.

You should now be able to 1. Explain why evolution does not lead to perfection. 2. Describe the levels of organization in an animal’s body. 3. Describe the four main types of animal tissues. Note their structures and their functions. 4. Explain how the structure of organs is based on the cooperative interactions of tissues. 5. Explain how organ systems work together to perform life’s functions.

You should now be able to 6. Describe the general structures and functions of the 12 major vertebrate organ systems. 7. Describe the systems that help an animal exchange materials with its environment. 8. Define the concept of homeostasis and illustrate it with examples. 9. Explain how negative feedback is used to regulate internal body temperature.

Function 20. 4 Epithelial tissue 20. 5 Connective tissue covers the body and lines binds and supports its organs and cavities. other tissues. 20. 6 Muscle tissue functions in movement. 20. 7 Nervous tissue forms a communication network. Structure Figure 20. UN 02 Sheets of closely packed cells Long cells (fibers) with contractile proteins Neurons with branching extensions; supporting cells Example Sparse cells in extracellular matrix Columnar epithelium © 2018 Pearson Education, Inc. Loose connective tissue Skeletal muscle Neuron