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Animal Tissues and Organ Systems

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1 Animal Tissues and Organ Systems
Chapter 28 Animal Tissues and Organ 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 Insert label and caption for any figures here.

3 Levels of Organization
A Cell (muscle cells) B Tissue (cardiac muscle) C Organ (heart) Figure 28.1 Levels of organization in a vertebrate (human) body. 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
Figure 28.7 Blubber-encased walrus resting on an ice floe. Blubber is a special type of adipose tissue. Like other marine mammals, walruses have a layer of blubber beneath their skin. Fat is less dense than water, so being encased in blubber helps a walrus float. Blubber is also springy. Unlike most adipose tissue, it includes many collagen and elastin fibers that cause it to spring back when compressed. This springiness reduces the energy the walrus expends while swimming. A coat of blubber also helps a walrus retain body heat. Even when the outside temperature dips far below freezing, a walrus’s core body temperature remains about the same as yours.

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 Figure Neuron and associated neuroglial cell.

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 Figure Organ system interactions that keep the body supplied with essential substances and eliminate unwanted wastes. 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 Insert label and caption for any figures here.

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) Figure 29.3 Some of the major nerves of the human nervous system. 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 Figure 29.4 Typical structure of the three types of neurons. Arrows indicate the direction of information flow among them.

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) Figure 29.9 Myelinated axon. Neuroglial cells produce the sheath that wraps around and insulates 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?
Table 31.1 Examples of Human Endocrine Glands, Their Hormones, and Hormone Actions

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? Figure 31.9 Secondary sexual characteristics. Testosterone secreted by testes stimulates growth of a male lion’s mane (left). A lioness (right) produces little testosterone, and does not develop a mane.

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

51 Do Invertebrates Have Hormones?
Hormone-signaling systems unique to invertebrates have also evolved Example: a hormone unique to arthropods called ecdysone controls molting (periodic shedding of the exoskeleton)

52 31.10 Application: Endocrine Disrupters
DDT (a pesticide) PCBs (used to make electronic products, caulking, and solvents) Phthalates (found in plastics and scented products) – these chemicals are still in wide use

53 The CDC had found BPA in the urine of 95% of adults sampled in 1988–1994 and in 93% of children and adults tested in 2003–04

54 Wednesday 9/24 Chap 33,34,35,36 Friday 9/26 Chap 37,38 Wednesday 10/1 EXAM #1

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