1. The Living World Fifth Edition George B. Johnson Jonathan B. Losos Chapter 28 The Animal Body and How It Moves Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 28.1 Innovations in Body Design Several evolutionary innovations in the design of animal bodies have led to the diversity seen in the kingdom Animalia  radial versus bilateral symmetry  no body cavity versus body cavity  nonsegemented versus segmented bodies  protostomes versus deuterostomes

3. Table 28.1 Innovations in Body Design

4. 28.2 Organization of the Vertebrate Body All vertebrates have the same general architecture: a long internal tube that extends from mouth to anus, which is suspended within an internal body cavity called the coelom  the coelom of many terrestrial vertebrates is divided into two parts thoracic cavity contains the heart and lungs abdominal cavity contains the stomach, intestines, and liver

5. 28.2 Organization of the Vertebrate Body A tissue is a group of cells of the same type that performs a particular function There are four general classes of tissues  epithelial  connective  muscle  nerve

6. Figure 28.1 Vertebrate tissue types

7. 28.2 Organization of the Vertebrate Body Organs are body structures comprised of several different tissues grouped together into a larger structural and functional unit An organ system is a group of organs that work together to carry out an important function

8. Figure 28.2 Levels of organization within the vertebrate body

9. There Are 11 Principal Organ Systems in the Vertebrate Body skeletal circulatory endocrine nervous respiratory immune and lymphatic digestive urinary muscular reproductive integumentary

10. Figure 28.3 Vertebrate body organ systems

12. 28.3 Epithelium Is Protective Tissue The epithelium functions in three ways  to protect the tissues beneath them from dehydration  to provide sensory surfaces many of a vertebrate’s sense organs are modified epithelial cells  to secrete materials most secretory glands are derived from pockets of epithelial cells

13. Figure 28.4 The epithelium prevents dehydration

14. 28.3 Epithelium Is Protective Tissue Epithelial cells are classified into three types according to their shapes Layers of epithelial tissue are usually one or two cells thick but the sheets of cells are tightly bound together Epithelium possesses remarkable regenerative abilities

15. 28.3 Epithelium Is Protective Tissue There are two general kinds of epithelial tissue  simple epithelium is only one cell layer thick and is important for exchanging materials across it  stratified epithelium is multiple cell layers in thickness and provides for cushioning and protection found in the skin, it is continuously replaced

16. 28.3 Epithelium Is Protective Tissue Pseudostratified epithelium is a special epithelium found lining the respiratory tract that resembles stratified epithelium Cuboidal epithelium has a secretory function and often forms glands

17. Table 28.2 Epithelial Tissue

18. 28.4 Connective Tissue Supports the Body Connective tissue cells fall into three functional categories  defense (cells of the immune system)  support (cells of the skeletal system)  storage and distribution (blood and fat cells) All connective tissues share a common structural feature  they have an abundant extracellular material, called the matrix, between widely spaced cells

19. 28.4 Connective Tissue Supports the Body immune cells roam the body within the bloodstream and hunt invading microorganisms and cancer cells  there are two kinds of immune cells macrophages that engulf and digest invaders lymphocytes that attack virus-infected cells or make antibodies  these cells are collectively known as “white blood cells”

20. 28.4 Connective Tissue Supports the Body Three kinds of connective tissue are the principal components of the skeletal system  fibrous connective tissue made up by cells called fibroblasts that secrete structurally strong proteins in the spaces between the cells –collagen protein is an example  cartilage cartilage is firm but flexible due to its configuration of collagen  bone bone is stronger than cartilage because the collagen is coated with calcium phosphate salt, making the tissue rigid

21. 28.4 Connective Tissue Supports the Body Some connective tissue cells are specialized to accumulate and transport particular molecules  adipose tissue is made up of fat- accumulating cells that contain vacuoles for storing fat  erythrocytes are red blood cells that transport O 2 and CO 2 in blood in addition, the red blood cells move in the plasma, which is a solvent for many substances

22. Table 28.3 Connective Tissue

23. 28.4 Connective Tissue Supports the Body The vertebrate endoskeleton is strong because of the structural nature of bone Bone is a dynamic tissue that is constantly being reconstructed  the outer layer of bone is very dense and compact and called compact bone  the interior of bone has a more open lattice structure and is called spongy bone red blood cells form in the marrow of spongy bone

24. 28.4 Connective Tissue Supports the Body New bone is formed in two stages  first, osteoblasts lay down collagen fibers along lines of stress  then calcium minerals impregnate the fibers Bone is laid down in thin, concentric layers  the layers form as a series of tubes around a narrow central channel called a central canal (Haversian canal)

25. Figure 28.5 The structure of bone

26. 28.4 Connective Tissue Supports the Body There is dynamic bone “remodeling” going on all the time  osteoblasts deposit bone while osteoclasts break down bone and release calcium As a person ages, the backbone and other bones tend to decline in mass  excessive bone loss is a condition called osteoporosis

27. Figure 28.6 Osteoporosis

28. 28.5 Muscle Tissue Lets the Body Move Muscle cells are the motors of the vertebrate body  they have many contractible proteins fibers, called myofilaments, inside of them the proteins actin and myosin make up the myofilaments  there are three different kinds of muscle in vertebrates smooth muscle skeletal muscle cardiac muscle

29. Table 28.4 Muscle Tissue

30. 28.5 Muscle Tissue Lets the Body Move Smooth muscle cells are long and spindle-shaped  each cell contains a single nucleus  smooth muscle is the least organized of the types of muscle tissue  it is found in areas such as the walls of blood vessels and the gut

31. 28.5 Muscle Tissue Lets the Body Move Skeletal muscle move the bones of the skeleton  skeletal muscles fuse to form one very long fiber with the nuclei pushed out to the periphery of the cytoplasm  each muscle fiber consists of many elongated myofibrils

32. Figure 28.7 A skeletal muscle fiber, or muscle cell

33. 28.5 Muscle Tissue Lets the Body Move Cardiac muscle is comprised of chains of single cells, each with its own nucleus  these chains are organized into fibers that branch and interconnect to form a network  each muscle cell is coupled to its neighbors electrically by gap junctions an electrical impulse passes from cell to cell across the gap junctions, causing the heart to contract in an orderly fashion

34. 28.6 Nerve Tissue Conducts Signals Rapidly Nerve cells carry information rapidly from one vertebrate organ to another Nerve tissue is comprised of two types of cells  neurons are specialized for transmitting nerve impulses  glial cells are supporting cells that supply neurons with nutrition, support, and insulation

35. 28.6 Nerve Tissue Conducts Signals Rapidly Each neuron is comprised of three parts  a cell body that contains the nucleus  dendrites that extend from the cell body and act as antennae to receive nerve impulses  an axon that is a single, long extension which carries nerve impulses away from the body some axons can be quite long

36. Figure 28.8 Neurons carry impulses

37. 28.6 Nerve Tissue Conducts Signals Rapidly Neurons have three general categories  sensory neurons carry electrical impulses from the body to the central nervous system  motor neurons carry electrical impulses from the central nervous system to the muscles  association neurons occur within the central nervous system and act as a connector between the sensory and motor neurons

38. Table 28.5 Nerve Tissue

39. 28.7 Types of Skeletons Animals are able to move because the opposite ends of their muscles are attached to a rigid scaffold, or skeleton  there are three types of skeletons in the animal kingdom hydraulic skeletons are fluid-filled cavities encircled by muscles that raise the pressure of the fluid when they constrict exoskeletons surround the body as a rigid hard case to which muscles attach internally endoskeletons are rigid internal skeletons to which muscles are attached

40. 28.7 Types of Skeletons Figure 28.9 Earthworms have a hydraulic skeleton Figure 28.10 Crustaceans have an exoskeleton Figure 28.11 Snakes have an endoskeleton

41. 28.7 Types of Skeletons The human skeleton is made up of 206 bones  axial skeleton made up of the skull, backbone, and rib cage  appendicular skeleton made up of the bones of the arms and legs and the girdles where they attach to the axial skeleton –pectoral girdle forms the shoulder joint –pelvic girdle forms the hip joint

42. Figure 28.12 Axial and appendicular skeletons

43. 28.8 Muscles and How They Work Skeletal muscles move the bones of the skeleton  tendons are straps of dense connective tissue that attach muscles to bone the origin of the muscle is the end of the muscle attached to a bone that remains stationary during a contraction the insertion of the muscle is attached to a bone that moves if the muscle contracts  bones pivot about flexible connections called joints

44. Figure 28.14 The muscular system

45. 28.8 Muscles and How They Work Muscles can only pull because myofibrils contract rather than expand  the muscles in the movable joints of vertebrates are attached in opposing pairs called flexors and extensors when contracted they move the bones in different directions

46. Figure 28.14 Flexor and extensor muscles

47. 28.8 Muscles and How They Work All muscles contract but there are two types of contractions  isotonic contraction is when the muscle shortens as it contracts  isometric contractions is when the muscle does not shorten when it contracts this would be associated with trying to lift something extremely heavy

48. 28.8 Muscles and How They Work The sliding filament model of muscular contraction describes how actin and myosin cause muscles to contract  the head of a myosin filament binds to an actin filament  but first, ATP is used to flex the myosin head  when the muscle contracts, the myosin head returns to its original shape and pulls the actin it is attached to along with it

49. Figure 28.15 How myofilament contraction works

50. 28.8 Muscles and How They Work As one after another myosin head flexes, the myosin in effect “walks” step by step along the actin The contractile unit of muscle is called a sarcomere  the actin filaments are anchored to one end of the sarcomere called the z-line  myosin is interspersed between a pair of actin filaments connected to either end of the sarcomere

51. Figure 28.16 How actin and myosin filaments interact

52. 28.8 Muscles and How They Work In vertebrate skeletal muscle, contraction is initiated by a nerve impulse  neurotransmitters are secreted by the neuron to stimulate the muscle to contract by causing Ca ++ ions to enter the muscle  access to actin by myosin is normally blocked by a regulatory protein called tropomyosin in the presence of Ca ++, the tropomyosin shifts away to expose binding sites on the actin for myosin

53. Inquiry & Analysis Do the three modes of locomotion have the same or different costs? For any given mode of locomotion, what is the impact of body size on cost of moving? Graph of Effect of Body Size on Energy Costs of Motion