Review Exercises

1. Define anabolism and catabolism.

2. Distinguish between dehydration synthesis and hydrolysis.

3. Define peptide bond.

4. Define enzyme.

5. How does an enzyme interact with its substrate?

6. List three factors that increase the rates of enzyme-controlled reactions.

7. How are enzymes usually named?

8. Define cofactor.

9. Explain why humans require vitamins in their diets.

10. Explain how an enzyme may be denatured.

11. Define energy.

12. Explain how the oxidation of molecules inside cells differs from the burning of substances outside cells.

13. Define cellular respiration.

14. Distinguish between the anaerobic reactions and aerobic respiration.

15. Explain the importance of ATP to cellular processes.

16. Describe the relationship between ATP and ADP molecules.

17. Define metabolic pathway.

18. Describe the starting material and products of glycolysis.

19. State the products of the citric acid cycle.

20. How are carbohydrates stored?

21. Explain how one enzyme can regulate a metabolic pathway.

22. Describe how a negative feedback mechanism can help control a metabolic pathway.

23. Explain the chemical basis of genetic information.

24. Describe the chemical makeup of a gene.

25. Describe the general structure and components of a DNA molecule.

26. Distinguish between the functions of messenger RNA and transfer RNA.

27. Distinguish between transcription and translation.

28. Explain two functions of ribosomes in protein synthesis.

29. Distinguish between a codon and an anticodon.

30. Explain how a DNA molecule is replicated.

31. Define mutation, and explain how mutations may originate.

32. Define repair enzyme.

33. Explain how a mutation may affect an organism's cells— or not affect them.

chapter objectives

After you have studied this chapter, you should be able to

1. Describe the general characteristics and functions of epithelial tissue.

2. Name the types of epithelium and identify an organ in which each is found.

3. Explain how glands are classified.

4. Describe the general characteristics of connective tissue.

5. Describe the major cell types and fibers of connective tissue.

6. List the types of connective tissue within the body.

7. Describe the major functions of each type of connective tissue.

8. Distinguish among the three types of muscle tissue.

9. Describe the general characteristics and functions of nervous tissue.

Understanding ^Vo rds adip-, fat: adipose tissue—tissue that stores fat. chondr-, cartilage:

chondrocyte—cartilage cell.

-cyt, cell: osteocyie—bone cell. epi-, upon, after, in addition: epithelial tissue—tissue that covers all free body surfaces. -glia, glue: neuroglia—cells that bind nervous tissue together. hist-, web, tissue: histology— study of composition and function of tissues. hyal-, resemblance to glass:

hyaline cartilage—flexible tissue containing chondrocytes. inter-, among, between:

intercalated disk—band of gap junctions between the ends of adjacent cardiac muscle cells. macr-, large: macrophage—large phagocytic cell. neur-, nerve: neuron—nerve cell. os-, bone: osseous tissue—bone tissue.

phag-, to eat: phagocyte—cell that engulfs and destroys foreign particles. pseud-, false: pseudostratified epithelium—tissue with cells that appear to be in layers, but are not. squam-, scale: squamous epithelium—tissue with flattened or scalelike cells. strat-, layer: stratified epithelium—tissue whose cells are in layers. stria-, groove: striated muscle— tissue whose cells have alternating light and dark cross-markings.

tudents preparing to enter health fields must memorize

Smany details of human anatomy and physiology. Traditionally, students have studied tissues and organs by using atlases of drawings and by dissecting cadavers. The National Library of Medicine offers a new way to study the human body. The Idea for the Visible Human Project was born In 1986, to complement the vast printed medical literature. Eight years later, a digital image library consisting of 1,871 one-millimeter-thick sections of a newly deceased man appeared on the Internet. In addition to digital images/photographs of thick sections, magnetic resonance images, computerized tomography scans, and X rays were taken of the whole body.

In life, the Visible Man was Joseph Paul Jernigan, executed by lethal injection in 1993 at age thirty-nine for killing an elderly man. After the execution, Jernigan's body was flown to the University of Colorado Medical Sciences Center where, within eight hours of death, the imaging began. Researchers saw it as a rare opportunity to obtain a healthy body soon after death. Medical ethicists, concerned with the rights of death row inmates, however, contend that when Jernigan willed his body to science, he may not have wanted every nuance of his anatomy to appear on computer screens everywhere—more likely he envisioned a fate on a dissection table. But Jernigan's lawyer maintains that his client willed his body to science to atone for his crime, and relatives of his victim agree.

The Visible Woman is a fifty-nine-year-old who died of a heart attack. Her sections were taken at 0.33-millimeter intervals, yielding more than 5,000 images of her anatomy. This distance is equal for all three axes in space, which makes it easier to derive three-dimensional reconstructions.

The Visible Human Project is described as a "unique interactive anatomical digital atlas." But much work lies ahead to classify, identify, measure, and label all structures. This will entail tracing many structures through several slices, to reconstruct tissues in three dimensions. According to the National Library of Medicine, "The larger, long-term goal of the Visible Human Project [is] to transparently link the print library of functional-physiological knowledge with the image library of structural-anatomical knowledge into one unified resource of health information."

In all complex organisms, cells are organized into layers or groups called tissues. Although the cells of different tissues vary in size, shape, arrangement, and function, those within a tissue are quite similar.

C>0 Reconnect to chapter 3, Intercellular Junctions, page 70.

Usually, tissue cells are separated by nonliving, intercellular materials that the cells produce. These intercellular materials vary in composition and amount from one tissue to another and may be solid, semisolid, or liquid. For example, a solid (mineral) separates bone tissue cells, whereas a liquid (plasma) separates blood tissue cells.

Tissues are maintained throughout life because as some cells die, others divide, providing replacements. Cells that have the ability to divide many times and yield new cells that then specialize are called stem cells. Those stem cells that can give rise to a great variety of cell types are termed pluripotent; stem cells with more restricted potentials are termed multipotent or progenitor cells. Groups of stem cells set aside within tissues enable the body to replace worn or damaged parts. Some stem cells can move in the body to a site of injury, and then divide and give rise to new cells that specialize in a way that replaces the damaged cells. Certain bone marrow cells, for example, follow signals to injury sites, where they divide and produce cells that become blood, cartilage, bone, adipose cells, or connective tissue—whatever is required in the healing process.

The best-studied progenitor cells are those in the bone marrow, which give rise to all blood cell types and certain cells of the immune system. More recently discovered is "brain marrow," which consists of collections of neural stem cells that line spaces in the brain. Under certain conditions, they can give rise to new nervous tissue. Researchers are currently identifying sources of stem cells in all tissues, and hope to use them to grow new tissues in an approach called regenerative medicine. Replacement neural tissue, for example, is being developed to treat spinal cord injuries and neurodegenerative disorders.

The tissues of the human body include four major types: epithelial, connective, muscle, and nervous. These tissues associate and interact to form organs that have specialized functions. Table 5.1 compares the four major tissue types.

This chapter examines in detail epithelial and connective tissues. Chapter 9 discusses muscle tissue, and chapters 10 and 11 detail nervous tissue.

D What is a tissue?

^9 How are tissues maintained?

^9 List the four major types of tissue.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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