Name Date Class

Chapter 13 Bones and Muscles · Section 1 Summary

Organ Systems and HomeostasisKey Concepts

. What are the levels of organization in the body?

. What systems are in the human body, and what are their functions?

. What is homeostasis?

The levels of organization in the human body consist of cells, tissues,organs, and organ systems. A cell is the basic unit of structure and functionin a living thing. Cells perform the basic processes that keep organisms alive.

A tissue is a group of specialized cells that perform the same function.The human body contains four basic types of tissue: muscle tissue, nervetissue, connective tissue, and epithelial tissue. Muscle tissue can contract, orshorten. This tissue is what makes parts of your body move. Nervous tissuecarries messages back and forth between the brain and every other part ofthe body. It directs and controls the body. Connective tissue providessupport for your body and connects all its parts. Bone, fat, and blood are allconnective tissues. Epithelial tissue covers the surfaces of your body. Theskin and the lining of the digestive system are examples of epithelial tissue.

An organ is a structure that is composed of different kinds of tissue anddoes a specific job. Each organ in your body is part of an organ system. Anorgan system is a group of organs that work together to perform a majorfunction. The human body has 11 organ systems. The integumentary,skeletal, and muscular systems provide structure and allow movement.The circulatory, respiratory, digestive, excretory, immune, andreproductive systems carry out the processes of life. The nervous andendocrine systems provide control over body processes. For each system tofunction, its organs and tissues must work together. And so must its cells.

The integumentary system is made up of skin, hair, and nails. Your skincreates a barrier that protects your body from injury and disease. It alsohelps regulate body temperature, remove wastes, and keep cells from dryingout.

Your skeletal system includes your bones and other connective tissue.The skeleton supports the body and gives it structure. It also protects yourbody's organs, produces blood cells, and stores calcium and other minerals.

Most muscles in your body are attached to bones. These muscles work bypulling on bones. Muscle cells that move your bones form bundles of fibersthat work together. Fiber bundles work in muscle groups, such as the biceps.

The circulatory system transports food and oxygen to body cells andcollects wastes. The heart pumps blood through the body by way of tube-like vessels called arteries, veins, and capillaries. Blood is a mix of fluid andcells.

The lungs are the main organs of your respiratory system. Air moves intoand out of your lungs when you breathe. Your air passages end in tinyclusters of tissues where oxygen and carbon dioxide are exchanged betweenthe air and the blood.

@ PearsonEduooffon,Inc.,publishingasPearsonPrenffceHall.Allrightsreserved.

244

Name Date Class

Bones and Muscles · Reading/Notetaking Guide

Digestion is the breakdown of food into small molecules the body canuse. Food enters the digestive system through the mouth and movesthrough the stomach and small intestine. Enzymes from these organs andfrom the liver and pancreas help digest the food. In the small intestine,specialized cells absorb the nutrients into the bloodstream. Leftover materialmoves to the large intestine where water is removed. The solid waste passesout of the body.

The excretory system removes wastes from the blood that have beenproduced by cell activities. The kidneys are the major organs of the excretorysystem. Each kidney contains millions of nephrons that filter wastes fromthe blood. These wastes are mixed with water to make urine. The urinarybladder stores urine until it passes out of the body through the urethra.

Yourimmune system protects you from infection caused by pathogens-disease-causing bacteria and viruses. Specialized cells target and destroypathogens. Other cells make antibodies, which are proteins that helpdestroy pathogens. Your immune system can produce more antibodies veryquickly if you are exposed to the same pathogens again. This ability to fightoff pathogens before they can cause disease is called immunity.

The reproductive system produces sex cells.When the DNA from a malesex cell and a female sex cell combine, anew individual can form. The organsof the reproductive system also produce chemicals that regulate the physicaldevelopment of the maturing body.

The nervous system takes in information from your environment andyour body and allows you to respond in some way. Your brain, spinal cord,and specialized nerve cells make up the nervous system. Nerve cellstransmit information between the parts of your body and the spinal cord andbrain.

The endocrine system consists of specialized glands scatteredthroughout the body. These glands produce hormones that are released intothe blood. Hormones help regulate the activities of organs and organsystems. Hormone levels can go up or down, depending on signals fromother glands or from your brain.

All the systems of the body work together to maintain homeostasis, thebody's tendency to keep an internal balance. Homeostasis is the process bywhich an organism's internal environment is kept stable in spite ofchanges in the external environment. Sometimes, things can happen tothrow offhomeostasis. As a result, your heart may beat more rapidly or yourbreathing may quicken. These are signs of stress, the reaction of your bodyto potentially threatening, challenging, or disturbing events. When the stressis over, homeostasis is restored, and the body returns to its normal state.

@ PeOlson Education, Inc., publishing os Peorson Prennce Hall. All rights reserved.

245

Name Date Class

Bonesand Muscles · Reading/Notetaking Guide

Organ Systems and Homeostasis (pp.508-517)This section tells how the body is organized and describes the systems in the huma11

body and their functions.

Use Target Reading Skills

As you read, take notes on the main ideas and important details. Consider the KeyConcepts and Key Terms. Use the graphic organizer below to take notes.

@ PearsonEducation,Inc., publishingasPearsonPrenticeHall.All lights reserved.

246

Recall Oues and Questions Notes

What are the levels of organizationin the body?

Name Date Class

Bonesand Muscles · Reading/Notetaking Guide

Introduction (p. 508)

1. List the levelsof organizationin the human body,starting with thesmallestunit.

a. b.d.c.

Cells (p. 509)

2. The basic unit of structure and function in a living thing is a(n)

3. Circle the letter of the outside boundary of an animal cell.

a. cytoplasmb. nucleusc. tissued. cell membrane

4. The control center that directs the cell's activities and contains information thatdetermines the cell's form and function is the

5. What is the cytoplasm?

6. Is the following sentence true or false? Cells carryon the processes that keeporganisms alive.

Tissues (p. 510)7. What is a tissue?

@ PearsonEducation,Inc., publishingasPearsonPrenticeHall.All rtghtsreserved.

247

Name Date Class

Bones and Muscles · Reading/Notetaking Guide

Organ Systems and Homeostasis (continued)

8. Complete the table to show the functions and examples of the tissues inthe human body.

Organs and Organ Systems (pp. 510-515)

9. A structure that is made up of different kinds of tissues and does specificjobs is a(n)

10. Circle the letter of the unit of organization that represents an organ.a. muscle cellb. bloodc. heart

d. digestive system

@ PearsonEducation,Inc., publishingasPearsonPrenticeHall.All rightsreserved.

248

Tissues in the Human Body

Tissue Function Example

Muscle

Nervous

Connective

Epithelial

Name Date Class- .

Bones and Muscles · Reading/Notetaking Guide

11. Is the following sentence true or false? An organ has a specific job thatismore complex than that of a tissue.

12. What is an organ system?

Match the organ system with its function.

Organ Systems Functions

13. endocrine a. Takes oxygen into the body

14. circulatory b. Supports and protects the body

15. excretory c. Removes wastes

16. respiratory d. Controls body process by means of chemicals

17. digestive e. Takes food into the body and breaks it down

18. skeletal f. Transports materials to and from body cells

19. muscular g. Takes in information from the environment and

20. integumentary from within the body and commands the body torespond

21. immuneh. Protects the body from disease-causing bacteria and

viruses22. reproductive

23. nervousi. Protects the body from injury and diseaseand helps

regulate body temperature

j. Contains organs that produce sex cells

k. Works to move the body by pulling on the skeleton

Homeostasis (pp. 516-517)

24. The processby which an organism's internal environment is kept stablein spite of changesin the external environment is called

25. How does your body maintain a constant temperature on a hot day?

26. What is stress?

@ PearsonEducation,Inc., publishingasPearsonPrenticeHall.All rightsreserved.

249

Name Date Class

Bones and Muscles · Review and Reinforce

Organ Systems and HomeostasisUnderstanding Main IdeasThe illustration below shows the units of organization in a reptile. The units arenumbered 1-4. Label the numbered units of organization in the spaces provided.

1.

2.

3.

4.

Building VocabularyFill in the blank to complete each statement.

5.

6.

is the body's tendency to keep an internal balance.

tissue makes up organs that are able to contract, or

tissue makes up the organs that send messagesshorten.

to control the body.

7. The inside of the digestive system is lined with tissue.

8. The kidney is a(n) . The excretory system is a(n)

9.The major organs of the excretory system are the

tissue provides support for your body and connects all10. .its parts.

11. Disease-causing bacteria or viruses are known as

@ Pearson EdlKotion, Inc., publishing os Pearson Prentice Hall. All rights reserved.

17

When a doctor performs a transplant operation, he or she replaces a diseasedor damaged organ or tissue. Sometimes a tissue is moved from one place toanother on the same person. This procedure is called an autograft. (Auto-means "self," and -graft means "transplant.") A burn victim may have anautograft in which a section of his or her healthy skin is transplanted to coverthe bum.

Sometimes a person receives an organ or tissue fromanother person. This is called an allograft. (Alla- means"different.") An example of an allograft is thetransplantation of a kidney from the body of one person intothat of another person. One problem with allografts isrejection. Rejection occurs when the patient's bodyrecognizes the transplanted organ or tissues as foreign,similar to the way in which a mother cat recognizes a kittenfrom another litter as not belonging to her. Rejection is aserious problem because the body begins to attack thetransplanted organ or tissue. One way of preventingrejection is by giving the patient certain drugs.

Transplants are performed to save a patient'slife or to correct a serious medical condition. For

example, a person with severe liver disease mightneed a new liver in order to survive. Transplanting a part of the eye calledthe cornea can help some blind people to see. The illustration shows some ofthe many organs and tissues that doctors can transplant.

Name Date

Bonesand Muscles · Enrich

Organ and Tissue Transplants

Class

lungblood heart

Answer the following questions on a separate sheet of paper.

1. Autografts are never rejected. Why do you think this is true?2. Why do you think doctors try to use autografts rather than allografts on

burn patients?3. A patient's body is less likely to reject an allograft if it comes from a close

relative. Why do you think this is true?4. Do you think doctors would have more difficulty transplanting an organ

system than transplanting an organ? Think of an example to explain youranswer.

@ Pemson Educotion, Inc., publishing os Pearson Prentice Holl. All rights reserved.

18