Animal Tissues and Organ Systems

1. Chapter 28 Animal Tissues andOrgan Systems

2. 28.1 How Are Animal Bones Organized? • Tissue found in all vertebrate bodies: • Epithelial tissue: covers body surfaces; lines internal cavities • Connective tissue: holds body parts together; provides structural support • Muscle tissue: moves the body or its parts • Nervous tissue: detects stimuli; relays information

3. Levels of Organization A Cell (muscle cells) B Tissue (cardiac muscle) C Organ (heart) D Organ System (circulatory system) E Organism (human)

4. An Internal Environment • An animal body consists mainly of water with dissolved salts, proteins, etc. • Most of this fluid resides inside cells • The rest is extracellular fluid: internal environment in which body cells live • In vertebrates, extracellular fluid consists mainly of interstitial fluid: fluid in spaces between body cells

5. Types of Connective Tissue • Cartilage: cells surrounded by a rubbery matrix of their own secretions • Adipose tissue: cells that make and store triglycerides; specialize in fat storage • Bone tissue: cells surrounded by a mineral-hardened matrix of their own secretions • Blood: plasma and cellular components (red cells, white cells, platelets)

6. Types of Connective Tissue

7. 28.5 What Are Muscle Tissues? • Muscle tissue: cells that contract (shorten) in response to stimulation • Coordinated contractions of layers or rings of muscles move the body or propel material through

8. Skeletal Muscle • Skeletal muscle tissue: helps move and maintain the positions of the body and its parts • Contains parallel arrays of long, cylindrical muscle fibers

9. Cardiac Muscle • Cardiac muscle tissue: found only in the heart wall • Appears striated • Has branching cells, each with a single nucleus

10. 28.6 What Is Nervous Tissue? • Nervous tissue: • Allows an animal to collect and integrate information about its internal and external environment • Controls the activity of glands and muscles • Main tissue of the vertebrate brain and spinal cord, and of the nerves that extend through the body

11. What Is Nervous Tissue? • Neurons: cells that transmit electrical signals along their plasma membrane and send chemical messages to other cells • Central cell body: contains nucleus and other organelles • Cytoplasmic extensions project from the cell body; function to receive and send electrochemical signals

12. What Is Nervous Tissue? signal-receiving extensions cell body of neuron signal-sending extension neuroglial cell wrapped around a signal-sending cytoplasmic extension of the neuron

13. What Are Vertebrate Organs and How Do They Interact? • Integumentary system: skin and skin-derived structures (e.g., hair and nails) • Nervous system: body’s main control center (brain, spinal cord, nerves, sensory organs) • Endocrine system: controls other organ systems

14. What Are Vertebrate Organs and How Do They Interact? • Muscular system: moves the body and its parts; regulates body temperature • Skeletal system: protects internal organs; stores minerals and produces blood cells • Circulatory system: heart and blood vessels; delivers oxygen and nutrients and clears wastes

15. What Are Vertebrate Organs and How Do They Interact? food, water intake oxygen inhaled carbon dioxide exhaled Digestive System Respiratory System nutrients, water, solutes carbon dioxide oxygen Urinary System Circulatory System water, solutes excretion of food residues transport of materials to and from cells elimination of soluble wastes, excess water, and salts

16. What Are Vertebrate Organs and How Do They Interact? • Lymphatic system: moves fluid (lymph) from tissues to blood and organs; protects the body against pathogens • Respiratory system: lungs and airways; delivers oxygen from air to blood and expels carbon dioxide • Digestive system: takes in and breaks down food; delivers nutrients to blood and eliminates undigested wastes

17. What Are Vertebrate Organs and How Do They Interact? • Urinary system: kidneys, bladder, etc.; removes wastes from blood and adjusts blood volume and solute composition • Reproductive system: gamete-making organs (ovaries or testes) • In females the uterus is the organ in which offspring develop

18. 28.8 How Does Skin Structure Affect Its Function? • Components of human skin: • Epidermis: stratified squamous epithelium with an abundance of adhering junctions • Human epidermis consists mainly of keratinocytes that make the waterproof protein keratin • Dermis: consists primarily of dense connective tissue with stretch-resistant elastin fibers and supportive collagen fibers • Blood vessels, lymph vessels, and sensory receptors weave through the dermis

19. Sun and the Skin • Melanin: protects skin by absorbing ultraviolet (UV) radiation • Some UV exposure is a good thing; it stimulates skin to produce a molecule that the body converts to vitamin D • Variations in skin color among human populations probably evolved as adaptations to differences in sunlight exposure

20. Cultured Skin Products • Skin is the only organ that is grown artificially for widespread medical uses • Cells from infant foreskins are grown in culture to produce thin sheets of cells that can be used to cover wounds, burns, or sores

21. 28.9 How Do Organ Systems Interact in Homeostasis? • In vertebrates, homeostasis involves interactions among sensory receptors, the brain, and muscles and glands • Sensory receptor: responds to a specific stimulus (e.g., temperature or light) • Negative feedback mechanism: change causes a response that reverses the change • Important for homeostasis

22. 28.10 Application: Growing Replacement Tissues • Animals commonly replace tissues lost to injury • Invertebrates have the greatest capacity for regeneration • Example: some sea stars can regrow an entire body from a single arm and a bit of the central disk

23. Chapter 29 Neural Control

24. 29.1 What Are the Types of Nervous Systems? • Cell-to-cell communication is important for an animal body to function as an integrated whole • Neurons make up the communication lines of nervous systems • Neurons transmit electrical signals and send chemical messages to other cells • Neuroglial cells support the neurons

25. Nerve Net • Animals with radial symmetry have a mesh of interconnected neurons, a nerve net • Information flows in all directions among cells • Sea anemones and other cnidarians are simple animals with nerve net • Echinoderms have nerve net + nerves • Nerve: bundle of neuron fibers (cytoplasmic extensions) wrapped in connective tissue

26. Getting a Head • Cephalization: evolutionary trend whereby neurons became concentrated at the “head” of bilateral animals • Planarian flatworms have a simple nervous system • A pair of ganglia (cluster of neurons) in the head serves as an integrating center • The ganglia connect to a pair of nerve cords (may nerve fibers)

27. Getting a Head • Annelids and arthropods have paired nerve cords that connect to a simple brain • Brain: central control organ of nervous system

28. The Vertebrate Nervous System • A dorsal nerve cord is one of the defining features of chordate embryos • Central nervous system: brain and spinal cord (evolved from dorsal cord) • Peripheral nervous system: nerves that carry signals between the central nervous system and the rest of the body

29. The Vertebrate Nervous System Brain cranial nerves (twelve pairs) cervical nerves (eight pairs) Spinal Cord thoracic nerves (twelve pairs) ulnar nerve (one in each arm) sciatic nerve (one in each leg) lumbar nerves (five pairs) sacral nerves (five pairs) coccygeal nerves (one pair)

30. How Does Neuron Structure Relate to Function? receptor endings peripheral axon cell body axon axon terminals cell body axon cell body axon axon terminals dendrites dendrites A B C

31. How Does Neuron Structure Relate to Function? • Structure of a neuron: • Cell body: contains nucleus and other organelles • Axon: transmits electrical signals and releases chemical signals at its terminal • Dendrites: receive chemical signals from other neurons

32. Conduction Along an Axon myelin sheath around axon node (unsheathed region of the axon) axon

33. 29.5 What Happens at a Synapse? • Action potentials cannot pass directly from a neuron to another cell • Signaling molecules (neurotransmitters) relay signals between a neuron and another cell • Synapse: region where axon terminals transmit neurotransmitters to another cell

34. 29.6 How Do Drugs Act at Synapses? • Psychoactive drugs alter brain function: • Mimic a neurotransmitter’s effect on a postsynaptic cell (e.g., morphine and heroin) • Stop neurotransmitter action (e.g., caffeine) • Inhibit neurotransmitter release (e.g., alcohol) • Block reuptake of neurotransmitter (e.g., cocaine) • Slow reuptake of neurotransmitter (e.g., antidepressants)

35. 29.7 What Is the Peripheral Nervous System? • Peripheral nervous system: all nerves outside the brain or spinal cord • Each nerve has outer layer of connective tissue surrounding bundles of axons • Two major functional divisions of the peripheral system: • Somatic nervous system • Autonomic nervous system

36. What Is the Peripheral Nervous System? • Somatic nervous system: controls skeletal muscles; relays sensory signals about movements and external conditions • Autonomic nervous system: relays signals to and from internal organs and glands • Parasympathetic neurons: encourage digestion and other “housekeeping” tasks • Sympathetic neurons: activated during stress and danger

37. Chapter 31 Endocrine Control

38. 31.1 What Are Animal Hormones? • Animal hormones: intercellular communication molecules that are secreted by endocrine cells • Distributed by the blood; typically act at a distant site from their source • Only cells with the appropriate receptors (target cells) can respond to a specific hormone

39. 31.2 What Are the Components of the Human Endocrine System? • Endocrine glands: aggregations of epithelial cells that produce and secrete hormones into the blood • Collectively make up the endocrine system • Portions of the endocrine system and nervous system are closely linked • Most organs respond to hormones and signals from the nervous system

40. What Are the Components of the Human Endocrine System?

41. Hormonal Growth Disorders • Growth hormone production surges during teenage years, causing a growth spurt, then declines with age • Oversecretion of growth hormone during childhood leads to pituitary gigantism • Too little growth hormone during childhood can cause pituitary dwarfism

42. Hormones, Stress, and Health • Long-term elevation of cortisol is unhealthy (example: Cushing’s syndrome): • Interferes with immunity, memory, and sexual function • Raises the risk of cardiovascular problems • Abnormally low levels of cortisol (example: Addison’s disease) • Fatigue, depression, weight loss, and darkening of the skin

43. 31.7 What Are Sex Hormones? • Sex hormones: steroid hormones produced by the gonads • Essential to reproductive function • Influence secondary sexual characteristics • Traits that differ between the sexes, but do not function directly in reproduction

44. What Are Sex Hormones?

45. What Are Sex Hormones? • Testosterone: responsible for development of male sex organs and secondary sexual characteristics • Estrogens: function in reproduction and cause development of female secondary sexual characteristics • Progesterone: prepares a female body for pregnancy and helps maintain a pregnancy

46. How Does the Pancreas Regulate Blood Sugar? • Beta cells secrete insulin when blood glucose levels rise • Insulin causes its target cells to take up and store glucose • Encourages synthesis of fats and proteins and inhibits their breakdown • Lowers blood glucose levels

47. How Does the Pancreas Regulate Blood Sugar? • Alpha cells secrete glucagon when blood glucose levels fall • Glucagon binds to receptors on liver cells: activates enzymes that break glycogen into glucose subunits • Raises the level of glucose in blood

48. How Does the Pancreas Regulate Blood Sugar? • The regulation of blood glucose is disrupted in diabetes mellitus • Type 1 diabetes: autoimmune response destroys insulin-secreting beta cells • Symptoms usually appear in childhood and adolescence • Type 2 diabetes: target cells do not respond to insulin • Symptoms typically start in middle age

49. 31.9 Do Invertebrates Have Hormones? • Some components of the endocrine system occur in invertebrates • Example: roundworms, annelids, and mollusks make steroid hormones

50. Do Invertebrates Have Hormones? • Invertebrates do not have the same glands as vertebrates do, but they produce the homologous hormones in other glands • Example: octopuses produce estrogens, progesterone, and cortisol in a gland near their eye