Systems of the Body 2 and The Stress
Process 1
September 7, 2004
Overview
Systems of the Body
• Digestive System
• Renal System
• Reproductive System
• Immune System
Methodology
The Stress Response
The Digestive System
Digestion – the conversion process in which
food is changed into a form which can be
used by cells.
Nutrients are supplied for growth and tissue
repair.
The Digestive System
• Bolus – food lubricated by saliva and formed into a soft, rounded
lump.
• Bolus passes through esophagus to stomach where gastric juices
further the digestive process.
• Pancreas secretes juices into duodenum to break down proteins,
carbohydrates and fats.
• Pancreas produces insulin to facilitate the entry of glucose into bodily
tissues.
• Liver produces bile to break down fats.
• Absorption of food takes place primarily in the small intestine.
• Food residue passes into large intestine and then rectum.
The Digestive System
Disorders
• Gastroenteritis – inflammation of the lining of the
stomach and small intestine
• Diarrhea – lining of the small and large intestine does not
absorb water and digested food
• Dysentery
• Peptic Ulcer – sore in the lining of the stomach or
duodenum
• Gallstones – stones in the gallbladder made of
cholesterol, calcium, bilirubin, and inorganic salts
• Appendicitis – accumulation of bacteria in the appendix
• Hepatitis – a contagious disease causing the
inflammation of the liver
The Renal System
• Structures - kidneys, ureters, urinary bladder,
and urethra
• Kidneys regulate bodily fluids, primarily they
produce urine.
• Urine consists of surplus water, surplus electrolytes, waste
products from metabolism of food, and surplus acids.
• Sodium and Potassium are key electrolytes.
The Renal System
Disorders
• Urinary tract infections – can be caused by bacteria
• Acute glomerular nephritis – inflammation of the
glomeruli of the kidneys; usually a secondary
response to a Strep infection
• Tubular necrosis – when cells in the tubules of the
kidneys are destroyed then acute renal shut down
can occur.
The Reproductive System
• Each female has two ovaries, which produce estrogen and
progesterone.
• One of the ovaries produces an ovum (egg) each month
• If the ovum isn’t fertilized by a sperm then it is flushed out of the uterine cavity with
the uterine endometrium and its blood vessels (menstruation)
• In males, the pituitary controls production of testosterone,
which is produced by the interstitial cells of the testes.
• Testosterone brings about the production of sperm and the
developing of male secondary sex characteristics.
• One sperm may fertilize the ovum, which then travels down
the fallopian tube and embeds itself in the uterine wall.
• The implanted embryo will develop over nine months.
The Reproductive System
Disorders
• Sexually transmitted diseases - herpes,
gonorrhea, syphilis, genital warts, Chlamydia,
AIDS
• STDs may result chronic pelvic inflammatory
disease in women.
• Reproductive system is vulnerable to testicular
cancer and gynecologic cancers.
• 8% of U.S. couples have fertility problems
The Reproductive System
Genetics and Health
• Genetic material for inheritance lies in the
nucleus of the cell in the form of 46
chromosomes.
• Studies of genetically-related family members,
twins, and adopted children are important in
determining the etiology and genetic influences
of diseases.
• Psychologists counsel couples regarding
genetic testing and the psychosocial
ramifications.
The Immune System
• Infection - The invasion of microbes and their
growth in the body.
• Four routes of infection
• Direct Transmission - contact
• Indirect Transmission – environmental transmission
• Biological Transmission – transmitting agent involved in the
disease process infects a target
• Mechanical Transmission – carrier transmits disease
The Immune System
The Course of Infection
Incubation period
• Period of nonspecific symptoms
• Acute phase
• Fatality OR
• Period of decline during which invading organisms are expelled
Infections may be localized, focal, or systemic. Primary
infections may lead to secondary infections.
The Immune System
Immunity
• The body’s resistance to injury from invading organisms.
• Temporary natural immunity when breast fed.
• Natural immunity is acquired through disease.
• Artificial immunity– vaccinations/inoculations
• The body has nonspecific and specific immune
mechanisms.
• Nonspecific – general responses to any type of infection or disorder
• Specific – targeted to fight particular microorganisms
The Immune System
Disorders
• AIDS – progressive impairment of immunity
• Cancer – depends heavily on
immunocompromise
• Autoimmunity – a condition characterized by a
specific humoral or cell-mediated immune
response that attacks the body’s own tissues.
• Certain forms of arthritis
• Multiple sclerosis
The Scientific Method
Theory:
Based on observations
Accept or
Reject Hypothesis
Hypothesis:
Predictions about
what will happen
Normal Science
Paradigm
Analyze Data
Data Collection
Methodology in Psychology
Empiricism
• Measures observable phenomenon
Theory Formulation and Hypotheses Testing
• Researchers observe every day phenomena.
• These observations form the basis of
scientific theory and inquiry.
Methodology
Experiments
Randomized
Clinical Trials
Correlational
Studies
Comparing
changes in
variables
Looking
forward,
longitudinal
research
Looking
backward
Prospective
Designs
Retrospective
Research
Methodology
Experiment
A study where there is random assignment to treatment groups in an
intervention focused on exercise and weight loss
Correlation
A study of the relationship between cultural identity and physical
symptoms
Prospective
A study following the physical and mental health indicators outcomes of
cancer patients 6 months, 1 year, and 2 years after chemotherapy
Retrospective
A study examining the past coping strategies of cardiac patients
Experimental Research
•
•
•
•
Random assignment to conditions
Manipulate independent variable to determine causality
Test statistically for significant differences between groups
Quasi-experimental methods – When individuals cannot be randomly assigned to
groups
Definitions
Independent Variable – what the researcher manipulates
Dependent Variable – the outcome (what changes based on the manipulation of the
independent variable)
Internal Validity – the degree to which the conditions of the experiment are causing the
effect
External Validity – generalizabilty of results to other contexts
Types
Laboratory studies
Clinical Trials
Strengths
Limitations
Evidence for causation
Generalizability
Generalizability – real world applications
Experimental Research
Experimental Design
Participants are randomly assigned to treatment groups in
a one-month intervention focused on exercise and
weight loss
Independent
Variable
Group 1 - Exercise
Every Day
Group 2 – Exercise
no more than
once a week
Dependent
Variable
Weight Loss After
One Month
Weight Loss After
One Month
Correlational Research
•
•
•
•
Systematically measures the relationship between variables
Correlation coefficient values (r) between -1, 1
Test for significant linear relationships between variables
This will be affected by sample size
•
In larger samples relationships may be significant with a relatively small r value.
Types
Surveys
Randomly selected populations
Strengths
Real World Context
May be most expedient method
Limitations
Correlation does not equal causation
Prospective Research
Prospective
A study following the physical and mental health indicators outcomes of
cancer patients 6 months, 1 year, and 2 years after chemotherapy
Type
Self-report over time
Strengths
Can examine changes over time
Relatively non-invasive
Limitations
Accuracy of self-report
Many factors over time effect determination causality
Retrospective Research
Retrospective Research
A study examining the past coping strategies of cardiac patients
Type
Self-report
Retrospective recall
Strengths
Examines patterns of past behavior in the context of a specific event
Limitations
Accuracy of memory and self-report
Limited determination of causality
Stress
A negative emotional experience accompanied by biochemical,
physiological changes that are directed either toward altering the
stressful event or accommodating to its effects (Baum, 1990)
• Stressful events are called stressors
•
•
•
•
Sitting in traffic
Bad relationships
Job interviews
Death in the family
• Perception affects the degree of stress experienced.
Stress
Personal
Resources
Personal
Resources
• Sufficient to meet
demands:
Low Stress
• Not sufficient to meet
demands:
High Stress
Stress: Fight or Flight Response
(Cannon, 1932)
When an organism perceives threat
• Sympathetic nervous system is aroused
• Endocrine system is aroused
• Organism is mobilized to attack the threat or to flee from the
threat
• Adaptive – allows quick response to threat
• Harmful – unabated stress is harmful to the
organism physically and psychologically
Stress
General Adaptation Syndrome (Selye, 1956)
• Nonspecific Response - The body responds to
stress with the same physiological reactions
Stress
Resistance
Normal level
of Resistance
Alarm
Exhaustion
Stress
General Adaptation Syndrome (Selye, 1956)
Three Phases in reacting to a stressor
• Alarm: The body’s first reaction
• Resistance: Occurs with continued exposure
• Exhaustion: Physiological resources are depleted
Stress
General Adaptation Syndrome (Selye, 1956)
Criticisms of the Model
• Limited role given to psychological factors
• Responses to stress are influenced by
individual difference, perceptions, and
preexisting physical and mental health
• Stress is assessed as an outcome
Stress
Cognitive (Psychological) Appraisal (Lazarus, 1968;
Lazarus & Folkman, 1984)
Two step process:
Primary appraisal process – What is at stake in the stress
situation?
• Is this event positive?
• Is this event neutral?
• Is this event negative?
• Has harm already been done?
• Is there a threat of future damage?
• How challenging is the event, that is, can I overcome
it or even profit from it?
Stress
Secondary Appraisal – What are my coping and
psychological resources in this situation?
How does the individual address the:
• Harm
• Threat
• Challenge
Stress
Tend and Befriend (Taylor et al., 2000)
• Model of affiliative responses to stress
• The sympathetic arousal underlying fight-orflight may be down-regulated in females
leading to nurturing behavior
• Females’ responses to stress evolved to care
for self and for offspring
Stress
• Oxytocin may be significant in female
responses to stress
• Animals and humans with high oxytocin levels are calmer, more
relaxed, more social, and more maternal in behavior
• Females rely more on social networks during
stress
Physiology of Stress
SAM – Sympathetic adrenomedullary system
Cannon’s “Fight-or-Flight” Response
• Sympathetic arousal stimulates the medulla of the
adrenal glands to secrete catecholamines
(epinephrine and norepinephrine)
• Blood pressure and heart rate increase, constriction
of peripheral blood vessels, increased sweating
Physiology of Stress
HPA – Hypothalamus-Pituitary-Adrenocoricotropic
Selye’s General Adaptation Syndrome
• Hypothalamus releases corticotrophin-releasing
factor (CRF) which stimulates the pituitary gland to
release ACTH (adrenocorticotropic hormone)
• ACTH stimulates the adrenal cortex to release
glucocorticoids, especially cortisol
Review figure 6.3
Physiology of Stress
Effects of Long-Term Stress
• Physiological changes are designed for fight of flight
(short-term mobilization)
• Long-term exposure to stress can have detrimental
physical consequences.
• Evidence supports that HPA activation may be more
significant than SAM activation when individuals are
under long-term stress.
• Corticosteroids have immunosuppressive effects
• Prolonged cortisol secretion is related to destruction of neurons in the
hippocampus.
Assessing Stress
• Self-reports of perceived stress
• Self-reports of life changes
• Behavioral measures, such as task
performance, under stress
• Physiological measures, such as skin
conductivity, heart rate, and blood pressure
• Biochemical markers, such as elevated cortisol
levels
Dimensions of Stressful Events
• Negative events are more likely to produce
stress than are positive events.
• However, people who hold negative views of themselves,
positive life events appear to have a detrimental effect on health
• Positive life events are linked to better health
in people with high self-esteem
• Uncontrollable, unpredictable life events are
most stressful
• Ambiguous events are more stressful
Dimensions of Stressful Events
• Overloaded people are more stressed than
are people with fewer tasks to perform
• More vulnerability to stress occurs in central
life domains than in one’s peripheral life
domains
• The most important aspects of an individual’s life are more
vulnerable to stress