Ch. 1 - Homeostasis

Question 1

Define physiology.

Answer 1

Physiology is the study of body functions.

Question 2

The nutrient-absorbing intestinal cells have a multitude of finger-like projections in contact with the digested food (see ❙Figure 16-20, p. 602). Based on your knowledge of structure– function relationships, explain the functional advantage of this structural feature.

Answer 2

to increase the surface area across which nutrients can be absorbed from the digestive tract into the blood

Question 3

Milk-secreting glands are surrounded by musclelike cells that squeeze out the milk in response to oxytocin secreted into the blood when a baby breast-feeds. Are milk-secreting glands exocrine or endocrine? Is oxytocin secreted by an exocrine or endocrine gland?

Answer 3

Milk-secreting glands are exocrine; they secrete through ducts to the outside. An endocrine gland secretes the hormone oxytocin into the blood.

Question 4

1. List and describe the levels of organization in the body.

Answer 4

• Chemical level: Various atoms and molecules make up all body structures.
• Cellular level: Specific chemicals are organized into living cells, which are the basic units of both structure and function.
• Tissue level: Groups of cells of similar specialization are organized into tissues.
• Organ level: An organ is made up of several tissue types that act together as a unit to perform a particular function or functions.
• Body system level: A body system is a collection of related organs that interact to accomplish a common activity essential for survival of the whole body.
• Organism level: The body systems are structurally and functionally packaged together into the whole body, which is a single, multicellular organism capable of living independently in the surrounding external environment.

Question 5

State the basic cell functions essential for its survival.

Answer 5

1. obtaining food and O2 from the environment surrounding the cell;
2. performing chemical reactions using food and O2 to provide energy for the cell;
3. eliminating to the surrounding environment wastes produced by these reactions;
4. synthesizing proteins and other components needed by the cell;
5. largely controlling exchanges between the cell and surrounding environment;
6. moving materials within the cell or, in the case of some cells, moving the cell;
7. being sensitive and responsive to changes in the surrounding environment;
8. reproducing (except for nerve cells and muscle cells).

Question 6

Name the four primary types of tissue and give an example of each.

Answer 6

• muscle tissue (skeletal muscle attached to bones, cardiac muscle in the heart, and smooth muscle in the walls of hollow organs);
• nervous tissue (in the brain, spinal cord, nerves, and special sense organs);
• epithelial tissue (skin, linings of hollow organs, exocrine glands, and endocrine glands); and
• connective tissue (loose connective tissue, tendons, bone, and blood)

Question 7

Indicate what four body systems are important in maintaining the proper concentration of the electrolyte calcium in the blood.

Answer 7

The urinary, digestive, endocrine, and skeletal systems all contribute to maintaining the proper concentration of calcium in the blood. The circulatory system merely transports this electrolyte.

Question 8

Distinguish among external environment, internal environment, intracellular fluid, extracellular fluid, plasma, and interstitial fluid.

Answer 8

• The external environment is the surrounding environment in which an organism lives.
• The internal environment is the fluid inside the body and outside the cells in which the cells live.
  
  • The extracellular fluid is the fluid inside the body and outside the cells and constitutes the internal environment.
    
    • The extracellular fluid is made up of the plasma, the fluid portion of the blood, and interstitial fluid, the fluid that surrounds and bathes the cells.
• The intracellular fluid is the fluid collectively within all body cells.

Question 9

Define homeostasis.

Answer 9

Homeostasis is the maintenance of a relatively stable internal environment.

Question 10

Draw a figure showing the interdependent relationship of cells, body systems, and homeostasis.

Answer 10

(See Figure 1-7, p 12)

Question 11

The hormone erythropoietin stimulates production of red blood cells. Would the rate of erythropoietin secretion go up, go down, or stay the same after you donate blood?

Answer 11

go up

Question 12

Distinguish between intrinsic controls and extrinsic controls.

Answer 12

• Intrinsic controls are inherent compensatory responses that act locally in an organ;
• extrinsic controls are systemic controls initiated outside an organ by the regulatory systems (nervous or endocrine systems) to alter the organ’s activity.

Question 13

Compare negative feedback and positive feedback.

Answer 13

In negative feedback, the output of a control system drives a controlled variable in the opposite direction of an initial change, thus counteracting the change.

In positive feedback, the output of a control system drives a controlled variable in the same direction as the initial change, thus enhancing the change.

Question 14

Draw a flow diagram showing the relationships among the components of a negative-feedback control system.

Answer 14

(See Figure 1-9a, p. 17)