This document discusses animal tissues and organ systems. It begins by defining key terms like tissue, organ, organ system, and homeostasis. The four main tissue types - epithelial, connective, muscle and nervous tissue - are described. An organ contains multiple tissue types and works with other organs in organ systems to maintain homeostasis. Examples of organ systems that interact to regulate internal conditions like temperature are provided. The largest organ, the skin, is also overviewed in detail. Potential applications of stem cell research to regenerate tissues are noted.

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ANIMAL TISSUES AND
ORGANS
Chapter Outline
IMPACTS/ISSUES: IT’S ALL ABOUT Organs in Body Cavities
POTENTIAL The Skin—Your Largest Organ
ANIMAL STRUCTURE AND FUNCTION Organ Systems
Organization and Integration HOMEOSTASIS IN ANIMALS
Evolution of Structure and Function Detecting and Responding to Change
TYPES OF ANIMAL TISSUES Negative Feedback
Epithelial Tissues Positive Feedback
Connective Tissues IMPACTS/ISSUES REVISITED
Specialized Connective Tissues SUMMARY
Muscle Tissues SELF-QUIZ
Nervous Tissue CRITICAL THINKING
ORGANS AND ORGAN SYSTEMS
Objectives
• Explain the potential of stem cells.
• Compare and contrast adult and embryonic stem cells.
• Understand the term dedifferentiate.
• List the barriers to using embryonic stem cells.
• Define tissue.
• Name the four major tissue types and their functions.
• Define organ and organ system and provide an example of each.
• Understand the process called homeostasis.
• Know what directs the evolution of anatomical structures.
• Explain the evolutionary history of lungs.
• Describe the features of epithelial tissue.
• Name three types of epithelial cells.
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2. • Compare and contrast exocrine glands and endocrine glands.
• Describe the features of connective tissue.
• Explain the difference between dense and loose connective tissue.
• Describe the different functions of cartilage, ligaments, and tendons.
• Explain why blood (a liquid) is considered connective tissue.
• Describe bone and adipose tissue.
• Compare and contrast the three types of muscle tissue.
• Describe nervous tissue; explain its function.
• Name the four major body cavities and their organ contents.
• Understand the structure, location, and function of epidermis, dermis, and hypodermis.
• Name each organ system in the human body, and briefly describe its function.
• Describe the function of melanin and its role in human skin.
• Explain how some organ systems interact to provide homeostasis in the human body.
• Explain the roles of sensory receptors, integrators, and effectors in homeostasis.
• Define the term negative feedback.
• Explain the steps in homeostasis of body temperature.
Key Terms
homeostasis fibroblast skeletal muscle tissue
organ gland smooth muscle tissue
organ system adipose tissue dermis
stem cell bone tissue epidermis
tissue blood nervous tissue
connective tissue cardiac muscle tissue neuron
endocrine gland cartilage negative feedback
epithelial tissue dense connective tissue positive feedback
exocrine gland loose connective tissue
Lecture Outline
19.1 Impacts/Issues: It’s All about Potential
A. Stem cells are self-renewing cells that can divide and produce more stem cells.
1. Adult stem cells replace some cells in adults such as blood cells.
a. Adult stem cells able to produce nerve or muscle cells are rare.
2. Embryonic stem cells can produce a wider variety of new cells.
a. Embryonic stem cells may be able to provide new nerve cells.
3. Research may overcome the limits of adult stem cells and make them as versatile as
embryonic stem cells.
19.2 Animal Structure and Function
A. Organization and integration
1. Tissues consist of one or more cell types that collectively perform a specific task.
a. Epithelial tissue covers body surfaces and lines internal cavities.
b. Connective tissue holds body parts together and provides structural support.
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3. c. Muscle tissue moves the body and its parts.
d. Nervous tissue detects stimuli and relays information.
2. An organ is a structural unit of two or more tissue types organized in a specific way and
capable of carrying out specific tasks.
a. The human heart is an organ that contains all four tissue types.
3. Organ systems are two or more organs that interact physically, chemically, or both, to
accomplish a specific task.
4. Organ systems accomplish tasks that are collectively called homeostasis.
a. Solute concentrations and internal temperature are examples of parameters that must be
maintained with certain limits by organ systems.
B. Evolution of structure and function
1. Anatomical traits vary among individual organisms.
2. Traits that best help an individual survive are preferentially passed on.
a. Structural traits become optimized for survival in specific environments.
3. Lungs allow animals to exist in a land environment and exchange gases with air instead of
water.
a. Lungs are adapted from tissue in the gut, not from gills.
19.3 Types of Animal Tissue
A. Epithelial tissues
1. sheetlike structure with no extracellular matrix
2. lack blood vessels
3. three cell types
a. simple squamous
b. cuboidal
c. simple columnar
4. gland cells
a. Exocrine glands release products into ducts for delivery.
b. Endocrine glands release products into the bloodstream.
5. Adults can renew epithelial tissues because the cells continue to divide in adults.
a. Epithelium is the tissue most likely to become cancerous.
B. Connective tissues
1. most abundant and widely distributed tissue in vertebrates
2. spread out in a cellular matrix and contain blood vessels
3. Soft connective tissue is composed of fibroblasts.
a. Fibroblasts make and secrete collagen and polysaccharides.
b. soft connective tissue categories:
loose – provides support under epithelium
dense – irregular; provides support in hypodermis, around organs
dense – regular; makes up tendons and ligaments to hold joints
C. Specialized connective tissue
1. Cartilage is a matrix of collagen and glycoproteins.
a. provides a model for developing bone
b. acts as a shock absorber in joints
2. Adipose stores fat.
3. Bone is a solid matrix of calcium that encloses bone cells.
a. provides support, protection, and movement
4. Blood cells are descendents of bone cells.
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4. a. transport oxygen, gases, proteins, nutrients, and hormones
b. provide defense against invasive organisms
D. Muscle tissue
1. The three types of muscle tissue respond to electrical signals from nerve
tissue.
2. Skeletal muscle
a. moves contractile units in response to nervous stimuli
b. striated (or striped) appearance; multiple nuclei
c. called voluntary because we can cause them to move
3. Cardiac muscle
a. also moves contractile units in response to stimuli
b. striated appearance; single nucleus
c. involuntary (we cannot consciously control)
4. Smooth muscle
a. lines internal organs, controls blood vessel diameter, constricts pupil
b. not striated; single nucleus
c. involuntary
E. Nervous Tissue
1. It detects and responds to stimuli.
2. Functional unit is an excitable neuron cell (responds to electrical stimuli).
3. Neurons vary in length from microscopic to three feet long in humans.
4. Neuroglia are support cells found in the nervous system.
19.4 Organs and Organ Systems
A. Organs in body cavities
1. Humans have bilateral symmetry and a coelom.
2. The coelom in humans is divided into two cavities.
a. The thoracic cavity contains heart and lungs.
b. The abdominal cavity contains digestive organs.
c. The pelvic cavity is a subdivision of the abdominal cavity and contains the bladder and
reproductive organs.
3. Cavities not derived from the coelom
a. The cranial cavity contains the brain.
b. The spinal cavity contains the spinal cord.
B. The skin: your largest organ
1. Epidermis – the outermost layer
a. Flattened, squamous cells are constantly being replaced from below.
b. Most epidermal cells are keratinocytes (make keratin).
c. Keratin provides waterproofing.
d. Keratinocytes store melanin.
2. Dermis – the middle layer
a. It consists of mostly dense connective tissue.
b. It contains sensory receptors, blood vessels, and sweat glands.
c. Hair follicles in the dermis are actually areas of epithelium that pouch into the dermis.
d. Oil glands secrete oil onto hair and keep it shiny and soft.
3. Hypodermis – the bottom layer
a. loose connective tissue and adipose tissue
4. The three layers of skin work together to:
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5. a. prevent invasion by pathogens.
b. detect changes in pressure, temperature, and touch.
c. regulate body temperature.
d. prevent water loss.
C. Sun, Aging, and the Skin
1. Melanin production increases in skin when exposed to the sun.
a. UV light is absorbed and thus does not penetrate deeper into body tissues.
b. UV light stimulates production of vitamin D.
c. Too much exposure to UV light can damage DNA and cause skin cancer.
2. Epidermal cells divide less frequently as we age.
a. Slower cell divisions in the epidermis cause thinning of the skin.
b. Smoking enhances this process by shrinking the skin’s blood supply.
c. Excessive tanning also accelerates the aging process in skin.
D. Organ Systems
1. The integumentary system (skin and its derivates such as hair, nails, fur, claws, quills, etc.)
is one type of organ system.
2. Humans and other vertebrates have numerous organ systems.
a. The digestive system – controls intake of food and digestive functions.
b. The respiratory system – controls oxygen intake and balance.
c. The circulatory system – delivers oxygen and nutrients to cells and removes carbon
dioxide and wastes.
d. The urinary system – filters wastes from the blood and stores urine.
e. The nervous system – detects changes in internal levels of water, nutrients, solutes,
wastes; stimulates movement of muscles.
19.5 Control of Body Temperature
A. Detecting and responding to change
1. A sensory receptor is a cell or cell component that detects a stimulus.
2. Information from sensory receptors flows to the brain.
3. The brain evaluates the information and directs the appropriate bodily response.
B. Keeping temperature just right
1. Negative feedback is a process in which a change causes a response that reverses the
change.
2. Increased body heat (such as during vigorous exercise on a hot day) triggers sensory
receptors in the skin which signal the brain.
3. The brain directs the following responses:
a. Increased breathing rate transfers heat from lungs to air.
b. Sweat glands increase output to cool the skin.
c. Blood flow shifts, so more blood goes to the skin to increase the heat that can be given
off by sweat glands.
d. Hormonal changes occur to damp energy and slow activity.
4. Receptors in the brain also detect cooling in the body, and some of the above processes are
reversed.
a. Additionally, minute muscle contractions occur (shivering) that increase heat output
inside the body.
b. Contraction of muscles attached to hair follicles causes hair to stand upright on the skin,
enhancing insulation by hair.
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6. 19.6 Impacts/Issues Revisited: It’s All about Potential
A. Stem cells are useful, if they can be induced to become specific cell types.
B. Research is directed at guiding stem cells along certain developmental paths.
C. University of Wisconsin researchers successfully stimulated stem cells to become motor
neurons.
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