3-07 Stress And Health

Front 1

Objective

Identify the three stages of Selye’s general adaptation syndrome.

Back 1

Selye proposed that any threat to the individual’s safety activates a generalized response, which he called the general adaptation syndrome. The initial alarm stage is characterized by increased activity of the sympathetic nervous system, readying the body for brief emergency activity. During the second stage, resistance, the sympathetic response declines, but the adrenal cortex secretes cortisol and other hormones that enable the body to maintain prolonged alertness, fight infections, and heal wounds. After intense, prolonged stress, the body enters the third stage, exhaustion. During this stage, the individual is tired, inactive, and vulnerable because the nervous system and immune systems no longer have the energy to sustain their heightened responses.

Front 2

Objective

Explain how the HPA system responds to stress.

Back 2

Stress activates two body systems. One is the autonomic nervous system, which prepares the body for brief emergency responses—fight or flight. The other is the HPA axis, which links the hypothalamus, pituitary gland, and adrenal cortex. Activation of the hypothalamus induces the anterior pituitary gland to secrete adrenocorticotropic hormone (ACTH), which in turn stimulates the human adrenal cortex to secrete cortisol. This enhances metabolic activity and elevates blood sugar levels and other nutrients.

Front 3

Objective

Distinguish among the three types of leukocytes.

Back 3

The most important elements of the immune system are the leukocytes, commonly known as white blood cells. These include the following three types of cells:

B cells, which mature mostly in the bone marrow, secrete antibodies—proteins that attack and destroy a specific type of foreign invader throughout the body. Every cell has surface proteins called antigens (antibody-generator molecules). The B cells recognize the “self” antigens, but when they find an unfamiliar antigen, they attack the cell. This kind of attack defends the body against viruses and bacteria; it also causes rejection of organ transplants. After the body has made antibodies against a particular intruder, it “remembers” the intruder and quickly builds more of the same kind of antibody if it encounters that intruder again.

T cells mature in the thymus gland. Several kinds of T cells attack intruders directly (without secreting antibodies), and some help other T cells or B cells to multiply.

Natural killer cells attack tumor cells and cells that are infected with viruses. Whereas each B or T cell attacks a particular kind of foreign antigen, natural killer cells nonspecifically attack all intruders.

Front 4

Objective

Indicate the effects of stress on the immune system.

Back 4

Stress affects the immune system in several ways. In response to a stressful experience, the nervous system activates the immune system to increase its production of natural killer cells and its secretion of cytokines. Even fear or anger enhances the immune system response, temporarily. During the stressful period of final exams, many college students have increased immune system activity. The elevated cytokine levels help combat infections, but they also trigger the brain to produce the same symptoms as if one were ill. Rats subjected to inescapable shocks show symptoms resembling illness, including fever, sleepiness, and decreased appetite.

Although the body’s response to stress may be helpful in the short run, a prolonged stress response is as draining on the body as a prolonged illness. A likely hypothesis is that prolonged increase of cortisol directs energy toward increasing blood sugar and metabolism, and therefore detracts energy from synthesizing proteins, including the proteins of the immune system.

Prolonged stress can also be harmful to the hippocampus. Stress releases cortisol, and cortisol enhances metabolic activity throughout the body. When metabolic activity is high in the hippocampus, the cells become more vulnerable. Toxins or overstimulation are then more likely than usual to damage or kill neurons in the hippocampus. High cortisol levels may be responsible for the deterioration of the hippocampus, and therefore the decline of memory, that occurs in older people. Older people with the highest cortisol levels tend to be those with the lowest hippocampus size and the greatest memory problems.

Front 5

behavioral medicine

Back 5

Branch of medicine that emphasizes the effects of diet on health, smoking, exercise, stressful experiences and other behaviors

Front 6

stress

Back 6

The nonspecific response of the body to any demand made upon it

Front 7

general adaptation syndrome

Back 7

Generalized response to stress

Front 8

cortisol

Back 8

Hormone that enables the body to maintain prolonged alertness, fight infections, and heal wounds

Front 9

HPA axis

Back 9

Hypothalamus, pituitary gland, and adrenal cortex system in response to stress; activation of the hypothalamus induces the anterior pituitary gland to secrete ACTH, which stimulates the adrenal cortex to secrete cortisol

Front 10

ACTH

Back 10

Hormone that stimulates the adrenal cortex to secrete cortisol, which enhances metabolic activity and elevates blood sugar levels and other nutrients

Front 11

immune system

Back 11

Consists of cells that protect the body against such intruders as viruses and bacteria

Front 12

leukocyte (white blood cells)

Back 12

Important elements of the immune system

Front 13

B cell

Back 13

Type of leukocyte; creates antibodies in response to specific antigens

Front 14

antibody

Back 14

Y-shaped proteins that attach to particular kinds of antigens

Front 15

antigen

Back 15

Surface proteins; antibody generator molecules

Front 16

T cell

Back 16

Type of leukocytes that attack specific intruders directly

Front 17

natural killer cell

Back 17

Type of leukocyte that attacks tumor cells and cells infected with viruses; nonspecifically attack all intruders

Front 18

cytokine

Back 18

Small proteins that combat infections and communicate with the brain to elicit appropriate behaviors

Front 19

psychoneuroimmunology

Back 19

Deals with the ways in which experiences, especially stressful ones, alter the immune system, and how the immune system in turn influences the central nervous system

Front 20

posttraumatic stress disorder

Back 20

Conditions that occurs in people who have endured terrifying experiences such as a life-threatening attack or watching someone else get killed; symptoms include frequent distressing recollections and nightmares about the traumatic event, avoidance of reminders of it, and exaggerated arousal in response to noises and other stimuli