Chapter 3—Cells and Tissues

1. In the cell, calcium is needed for blood clotting, iron is necessary to make hemoglobin, iodine is required to make the thyroid hormone that controls metabolism, and sodium and potassium ions are essential if nerve impulses are to be transmitted.

2. In addition to containing large amounts of water, all the cells of the body are constantly bathed in a dilute saltwater solution called interstitial fluid.

3. In general, all cells have 3 main regions or parts, a nucleus, cytoplasm, and a plasma membrane.

Name Structure FunctionErythrocyte Concave disk

shape, no organelles

To carry oxygen in the bloodstream

Epithelial cell Hexagonal shape; like a honeycomb; packed together in sheets

To cover and line body organs

Skeletal and smooth muscle

Elongated and filled with filaments

To move organs and body parts

Name Structure FunctionFat cell Huge spherical

shape, filled with a lipid droplet

To Store nutrients

Macrophage Has long psuedopods to crawl through tissue

To digest infectious micro-organisms

Neuron Long processes covered with plasma membrane

To gather information and control body functions

Name Structure Function

Oocyte Largest cell in the body, contains many copies of all organelles

To reproduce

Sperm Long and stream-lined, with a flagellum

Introduces DNA into the egg

5. In passive transport processes, substances are transported across the membrane without energy input from the cell.

6. Exocytosis is the means by which cells actively secrete hormones, mucus, or other cell products, or eject cellular wastes.

7. Endocytosis includes those ATP-requiring processes that take up, or engulf, extracellular substances by enclosing them in a vesicle.

8. The 4 primary tissue types, epithelium, connective, nervous, and muscle tissue interweave to form the fabric of the body.

9. Tissue Roles

-epithelium: covering

-connective: support

-muscle: movement

-nervous: control

10. Since epithelium forms the boundaries that separate us from the outside world, nearly all substances given off or received by the body must pass through the epithelium.

Describe the 4 functions of epithelium:

Protection: protects against bacterial and chemical damage

Absorption: absorb food substances into the body

Filtration: in the kidneys, it filters impurities out of the blood

Secretion: perspiration, oil, mucus, digestive enzymes are secreted through epithelia

12. Epithelial cells fit closely together to form continuous sheets. The membranes always have one free surface or edge. Epithelial cells have no blood supply of their own, but they regenerate themselves easily if well nourished.

13. Each epithelium is given 2 names. The first indicates the relative number of cell layers it has. The second describes the shape of its cells.

Difference between simple and stratified epithelium

Simple epithelium has 1 layer of cells.Stratified epithelium has more than 1

layer.

3 Basic Shapes of Epithelial Cells

Squamous: flattened like fish scales

Cuboidal: cube-shaped, like dice

Columnar: shaped like columns

16. Transitional epithelium is a highly modified, stratified squamous epithelium that form the lining of urinary organs. The ability of transitional cells to slide past one another and change their shape allows the ureter wall to stretch as urine flows through.

17. The secretions of endrocrine glands diffuse directly into the blood vessels that weave through the glands.

18. Connective tissue is the most abundant and widely distributed type of tissue in the body. Connective tissues are primarily involved in protecting, supporting and binding together other body tissues.

Tissue Description Function

Bone Bone cells sitting in cavities surrounded by a hard matrix

Protect and support other body organs

Cartilage Less hard and more flexible than bone

Cushion and protect bones

Tissue Description FunctionDense connective tissue

Collagen fibers; tendons and ligaments

Connect bones and muscles to one another

Loose connective tissue

Softer, more cells and fewer fibers

Areolar tissue cushions and protects organs

Blood Blood cells surrounded by fluid plasma

Transports oxygen and nutrients to body cells

20. Muscle tissues are highly specialized to contract to produce movement. Because they are elongated, muscle cells are called muscle fibers.

21. Skeletal muscle is packaged by connective tissue sheets into organs called skeletal muscles, which are attached to the skeleton. These muscles can be controlled voluntarily.

22. Cardiac muscle is found only in the heart. Cardiac muscle is under involuntary control, which means that we cannot consciously control the activity of the heart.

23. Smooth muscle is found in the walls of hollow organs. When it contracts, the cavity of an organ alternately becomes smaller or enlarges so that substances are propelled through the organ.

24. All neurons receive and conduct electrochemical impulses from one part of the body to another.

Tissue Repair

REGENERATION

FIBROSIS—SCAR TISSUE