1. Animal Systems 2: Response Chapter 28.1

2. How do animals respond to events around them? ► Most animals have a special nervous system to respond to events around them ► Nervous systems are composed of specialized nerve cells called neurons ► Information in the environment that causes an organism to react is called a stimulus

3. Nervous System ► The nervous system has two primary functions that are critical in maintaining life of the organism: ► 1. Sensory receptors allow organism to monitor its external environment and detect changes (ex increase in temperature)  This allows for activation of muscles and glands to respond to these environmental changes ► 2. Monitors organisms internal environment  Controlling heart rate and measuring nutrient levels

4. Neuron ► A neuron consists of several parts:  Soma- cell body  Dendrites- brings information to cell body  Axon-takes information away from cell body  Myelin sheath

6. Detecting Stimuli ► Animals ability to detect stimuli depends on specialized cells called sensory neurons ► Each type of sensory neuron responds to a particular stimulus such as light, heat or chemicals

7. Detecting Stimuli ► Humans share many types of sensory cells with other animals, many animals have types of sensory cells that humans lack. ► This is one reason why some animals respond to stimuli that humans cannot detect.

8. Processing Information ► When sensory neurons detect a stimulus, they pass info about it to other nerve cells called interneurons, which process information and determine how an animal responds ► The number of interneurons an animal has determines how complex an animal can be  Ex: some invertebrates such as cnidarians and worms have very few interneurons and are capable of only simple responses to stimuli

9. Responding ► When an animal responds to a stimulus, body systems (sensory neurons, nervous system and muscles) work together to generate a response ► Nerve cells called motor neurons carry “directions” from interneurons to muscles

10. Motor Neurons in Vertebrates ► There are three different forms of motor neurons in vertebrates depending on species  Muscles of the limbs which are involved in locomotion  Another involves brachial muscles (motorize the gills in fish)  Movement of cardiac and smooth muscles (muscles of the arteries)

11. Nervous System Evolution ► Animal nervous systems exhibit different degrees of cephalization and specialization ► Cephalization is the process through evolution of the sensory and neural organs to be concentrated in an anterior head

12. Invertebrates ► Invertebrate nervous systems range from simple collections of nerve cells to complex organizations that include many interneurons ► Cnidarians, such as jellyfishes, have simple nervous systems called nerve nets ► Nerve nets consist of neurons connected into a netlike arrangement with few specializations

13. Invertebrates ► In symmetric invertebrates, such as sea stars, some interneurons are grouped together into nerves, or nerve cords, that form a ring around the animals’ mouths and stretch out along their arms (sea stars) ► In other invertebrates, a number of interneurons are grouped together into small structures called ganglia, in which interneurons connect with one another

15. Organization of Interneurons ► Interneurons form ganglia in several places, with the largest ganglia typically located in the head region and called cerebral ganglia ► In some species, cerebral ganglia are further organized into a structure called a brain ► The brains of some cephalopods, such as octopi, enable complex behavior, including several kinds of learning

16. Parts of the Vertebrate brain ► Regions of the vertebrate brain include the cerebrum, cerebellum, medulla oblongata, optic lobes, and olfactory bulbs

17. Parts of the Vertebrate Brain ► The cerebrum is the “thinking” region of the brain. It is also involved in learning, memory and conscious thought  It receives and interprets sensory information and determines a response ► The cerebellum coordinates movement and controls balance ► The medulla oblongata controls the functioning of many internal organs ► Optic Lobes are involved in vision and olfactory bulbs are involved in the sense of smell

18. Brain Evolution ► Brain evolution, in vertebrates follows a general trend of increasing size and complexity from fishes, through amphibians and reptiles, to birds and mammals ► In fishes, amphibians, and reptiles, the cerebrum, or “thinking” region, is relatively small ► In birds and mammals, and especially in primates, the cerebrum is much larger and may contain folds that increase its surface area ► The cerebellum is also most highly developed in birds and mammals

20. Sensory Systems ► Sensory systems vary in complexity including both sensory neurons and other cells that help gather information ► Many invertebrates have sense organs that detect light, sound, vibrations, movement, body orientation, and chemicals in air or water  Flatworms, for example have simple eyespots that detect only the presence and direction of light

21. Chordate Sense Organs ► Although all mammalian ears have the same basic parts, they differ in their ability to detect sound ► Bats and dolphins can find objects in their environment using echoes of their own high-frequency sounds

22. Animal Systems 2: Movement and Support Chapter 28.2

23. Essential Questions ► What are the 3 types of skeleton? ► How do muscles enable movement?

24. Movement and Support ► An animal’s ability to move efficiently is greatly enhanced by rigid body parts. ► Animals have three main kinds of skeletal systems:  Hydrostatic skeletons  Exoskeletons  Endoskeletons

25. Hydrostatic Skeletons ► Found in many cold- blooded organisms and soft bodied animals with a fluid filled cavity ► The fluids held in a gastrovascular cavity can alter the animal’s body shape drastically by working with contractile cells in its body wall

26. Exoskeletons ► Many arthropods and most mollusks (snails and clams) have exoskeletons ► The exoskeleton of an arthropod is a hard body covering made of a protein called chitin ► Most mollusks have exoskeletons made of calcium carbonate

27. Exoskeleton Functions ► The various functions of an exoskeleton include:  Jointed exoskeletons enable various arthropods to swim, fly, burrow, walk, crawl, and leap  Provide watertight coverings that enable some arthropods to live in Earth’s driest places  Can provide physical protection against predators

28. Exoskeleton Disadvantages ► An external skeleton poses a problem when the animal needs to grow ► How is this fixed?  To increase in size, arthropods break out of their exoskeleton and grow a new one, in a process called molting  Exoskeletons are heavy

29. Endoskeleton ► An endoskeleton is a structural support within the body ► Echinoderms and vertebrates have endoskeletons ► Vertebrates endoskeleton is made of cartilage or a combo of cartilage and bone

30. Advantages and Disadvantages ► Disadvantage  Since it does not surround the body it cannot protect the body like an exoskeleton can ► Advantages  Provide strong, lightweight support  Can grow as the animal grows  No molting

31. Joints ► Arthropods and vertebrates can bend because many parts of their skeletons are connected by joints ► Joints are places where parts of a skeleton are held together in ways that enable them to move with respect to one another

32. Ligaments ► In vertebrates, bones are connected at joints by strong connective tissues called ligaments ► Most joints are formed by a combination of ligaments, cartilage, and lubricating joint fluid that enables bones to move without painful friction

33. Tendons ► Muscles are attached to bones around the joints by tough connective tissue called tendons ► Tendons are attached in such a way that they pull on bones when muscles contract

34. Muscles and Movement ► In many animals, muscles work together in pairs or groups that are attached to different parts of a supporting skeleton ► Muscles are specialized tissues that produce physical force by contracting, or getting shorter, when they are stimulated ► Muscles can relax when they aren’t being stimulated, but they cannot actively get longer

35. Movement ► In both arthropods and vertebrates, different pairs or groups of muscles pull across the joint in different directions ► When one muscle group contracts, it bends, or flexes, the joint ► When the first group relaxes and the second group contracts, the joint straightens ► The shapes and relative positions of bones, muscles, and joints are linked very closely to the functions they perform ► Differently shaped bones and muscles form limbs adapted for long-distance jumping (frogs), manipulating objects (raccoons), climbing trees (sloths), and flying (birds)

36. Animal Systems 2: Reproduction Chapter 28.3

37. Essential Questions ► How do sexual and asexual reproduction in animals compare? ► How do internal and external fertilization differ? ► Where do embryos develop? ► How are terrestrial vertebrates adapted to reproduction on land?

38. Reproduction ► Asexual reproduction  Requires only one parent  Individuals in favorable environmental conditions can reproduce rapidly  No genetic diversity ► Sexual reproduction  Requires 2 parents  New combinations of genes  Maintains genetic diversity  Better able to evolve/adapt to changing environments

39. Asexual Reproduction ► Animals reproduce asexually in many ways:  Some cnidarians divide into two  Some animals reproduce via budding, which produces new individuals as outgrowths of the body wall  The process parthenogenesis, produces offspring that carry DNA inherited only from their mothers

40. Sexual Reproduction ► Among annelids, mollusks, and fishes, some species are hermaphrodites  Can be both male and female or can convert from one sex to the other  Example: Clownfish may change from one sex to another as they mature

41. Reproductive Cycles ► Some invertebrates have life cycles that alternate between sexual and asexual reproduction. ► Parasitic worms and cnidarians alternate between forms that reproduce sexually and forms that reproduce asexually.

43. Internal & External Fertilization ► During internal fertilization, eggs are fertilized inside the body of the egg- producing individual  Includes many aquatic and all terrestrial animals ► In external fertilization, eggs are fertilized outside the body of the egg-producing individual  Includes ranges of aquatic invertebrates and vertebrate species

44. Embryos ► Oviparous species are those in which embryos develop in eggs outside the parents’ bodies ► Includes: most invertebrates, many fishes and amphibians, most reptiles, all birds, and a few odd mammals

45. Ovoviviparous Species ► In ovoviviparous species, embryos develop within the mother’s body, but they depend entirely on the yolk sac of their eggs. The young do not receive any additional nutrients from the mother ► The young either hatch within the mother’s body or are released immediately before hatching. They swim freely shortly after hatching.  Includes guppies and some shark species

46. Viviparous Species ► Viviparous species are those in which embryos obtain nutrients from the mother’s body  Occurs in most mammals, sharks, amphibians and reptiles ► In viviparous insects and in some sharks and amphibians, young are nourished by secretions produced in the mother’s reproductive tract ► Placental mammals use a placenta, an organ which enables exchange of respiratory gases, nutrients, and wastes between the mother and her developing young.

47. Metamorphosis ► Metamorphosis is a developmental process that leads to dramatic changes in shape and form ► In aquatic invertebrates they have a larval stage, which looks nothing like an adult ► Terrestrial invertebrates go through incomplete or complete metamorphosis. ► Amphibian metamorphosis is controlled by hormones.

48. Terrestrial Metamorphosis ► Incomplete metamorphosis: They have immature forms called nymphs that resemble adults but lack functional sexual organs and some adult structures (wings)  As they molt they acquire adult structures ► Complete metamorphosis: Larvae look nothing like their parents. A final molt causes a dramatic change into a pupa (larva to adult stage).

49. Reproductive Diversity in Chordates ► The amniotic egg evolved in reptiles, birds, and a few mammals, which is an embryo that develops outside its mother’s body and out of water. ► Early chordate eggs needed to develop in water.

50. Reproductive Diversity in Chordates ► Mammalian Reproductive Strategies  Monotremes: Lay amniotic eggs that are incubated outside her body, but are nourished by milk produced in mammary glands after the eggs hatch.

51. Reproductive Diversity in Chordates ► Mammalian Reproductive Strategies  Marsupials: Bear live young that complete their development in an external pouch.  Placentals: Use a placenta to exchange nutrients between embryo and mother.

52. Embryological Development ► During embryological development, the cells of most animal embryos differentiate into three layers called germ layers.  Endoderm (Innermost germ layer): Develop into the linings of the digestive and respiratory tract.  Mesoderm (Middle layer): Give rise to muscles, circulatory, reproductive, and excretory organs.  Ectoderm (Outermost layer): Produces the nervous system and skin.

53. Ectotherm ► Ectotherms are animals that regulate body temperature primarily by absorbing heat from, or losing heat to, their environment ► They have relatively low metabolic rates when resting, so their bodies don’t generate much heat ► Their muscles generate heat when active, but since most ectotherms lack effective body insulation, their body heat is easily lost to the environment

54. Endotherm ► An endotherm is an animal whose body temperature is regulated, at least in part, using heat generated by its body ► Have high metabolic rates that generate heat, even when they are resting ► Conserve heat through feathers, body fat, hair ► Remove excess heat through panting or sweating ► All mammals and birds

55. Animal Systems 2: Homeostasis Chapter 28.4

56. Homeostasis ► Homeostasis or control of internal conditions, is essential to an organism’s survival. ► For example, brain cells must be bathed in fluid with a constant concentration of water and be cleansed of metabolic waste products. Failure of this, for even a few minutes could lead to brain injury or death.

57. Interrelationship of Body Systems ► The digestive, respiratory, circulatory, excretory, nervous, muscular, and skeletal systems are all interconnected and work together to maintain homeostasis ► In most animals, respiratory and digestive systems would be useless without circulatory systems to distribute oxygen and nutrients ► The excretory system needs a circulatory system to collect carbon dioxide and nitrogenous wastes from body tissues and deliver them to the lungs and excretory organs ► Muscles wouldn’t work without a nervous system to direct them and a skeletal system to support them

58. Homeostasis Examples ► Fighting Disease  Immune system to distinguish foreign pathogens from own cells ► Chemical Controls  Endocrine glands regulate body activities by releasing hormones into the blood, where they are carried to the designated organs ► Body temperature control  Requires three components: a source of heat, a way to conserve heat when necessary, and a method of eliminating excess heat when necessary

59. Ectotherm ► Ectotherms are animals that regulate body temperature primarily by absorbing heat from, or losing heat to, their environment ► They have relatively low metabolic rates when resting, so their bodies don’t generate much heat ► Their muscles generate heat when active, but since most ectotherms lack effective body insulation, their body heat is easily lost to the environment

60. Endotherm ► An endotherm is an animal whose body temperature is regulated, at least in part, using heat generated by its body ► Have high metabolic rates that generate heat, even when they are resting ► Conserve heat through feathers, body fat, hair ► Remove excess heat through panting or sweating

61. Analgesia ► It is the loss of sensation of pain that results from an interruption in the nervous system pathway between a sense organ and brain. ► Different forms of sensation (touch, temperature and pain) can stimulate an area of skin travel to the spinal cord by different nerve fibres in the same nerve bundle. Therefore, any injury or disease affecting the nerve would abolish all forms of sensation in the area supplied by it ► When sensory nerves reach the spinal cord, however, their fibres separate and follow different courses to the brain