Ch 5 Flashcards
Consciousness
Awareness of oneself and the environment.
Biological Rhythms
A periodic, more or less regular fluctuation in a biological system. A biological clock in the brain governs: Hormone levels Urine volume Blood pressure
Biological Rhythms
Entrainment
The synchronization of biological rhythms with
external cues.
Endogenous
Rhythms that continue to occur even in the absence of
external cues.
Types of Endogenous Rhythms
1. Circadian Rhythms
1. Circadian Rhythms A biological rhythm with a period of about 24 hours Examples: sleep-wake cycle body temperature
Circadian rhythms exist in plants, animals,
insects, and human beings.
Reflect the adaptation of organisms to the many
changes associated with the rotation of the earth
on its axis.
Types of Endogenous Rhythms
2. Infradian Rhythms
2. Infradian Rhythms A biological rhythm that occurs less frequently than once a day. Often monthly or seasonally. Examples: Female menstrual cycle. Southern migration of birds in the fall. Hibernation of bears in the winter.
Types of Endogenous Rhythms
- Ultradian Rhythms
A biological rhythm that occurs more than once a day.
Often on a 90-minute schedule.
Example:
Stomach contractions
Hormone levels
Brain-wave responses during cognitive tasks
Circadian Rhythms
With External Cues
Without External Cues
Humans usually adapt to a strict 24-hour
schedule.
Biological rhythms become entrained to external
cues.
Without External Cues
Body temperature and certain hormone levels
still follow a cycle close to 24 hours.
The Body’s Clock Suprachiasmatic nucleus (SCN)
A tiny teardrop-shaped cluster
of cells in the hypothalamus.
Contains a biological clock that
governs circadian rhythms.
The Body’s Clock
The Process
Receptors in the back of the eye send information to the SCN about changes in light and dark. SCN responds by sending out messages that cause the brain and body to react to the light and dark changes.
The Body’s Clock
Melotonin
A hormone secreted by the pineal gland.
Involved in the regulation of circadian
rhythms.
Helps keep the biological clock in phase with
the light-dark cycle.
Directly promotes sleep in blind people who
lack light perception.
The Body’s Clock
Internal desynchronization
A state in which biological rhythms are not in phase with one another. Examples: Jet lag from airplane flights. Feeling tired and irritable when adjusting to a night shift.
The Body’s Clock
Three proposed methods to treat internal
desynchronization:
- Using bright lights to “reset” the clock in the SCN.
- Treating people with small amounts of melatonin
on a controlled schedule. - Combining melatonin treatment with light
therapy.
The Body’s Clock
Circadian rhythms can be affected by many
factors:
The Body’s Clock
Circadian rhythms can be affected by many
factors:
Moods & Infradian Rhythms
Seasonal affective disorder (SAD)
A controversial disorder in which a person experiences
depression during the winter and an improvement of
mood in the spring.
Evaluating the actual prevalence and treatment of SAD is difficult. Clinicians suggest that 20% of the population suffers from the disorder. Scientific surveys indicate that the prevalence of SAD is much lower: 2 to 3% of Canadians 1% of Americans 0 to 1% of Asians
Treating SAD
1. Phototherapy Sitting in front of a extremely bright fluorescent light. 2. Negative ion Therapy Exposure to high levels of negative ions.
Female Menstrual Cycle
Changes in a woman’s
hormones that direct her body
to release a tiny egg or ovum.
Average length is 28 days.
Day 1
Estrogen and progestrone are at their lowest level.
Inner lining of the uterus is discharged as menstrual blood.
Unfertilized ovum produced in the last cycle is discharged.
Day 2 through 12
Menstruation continues for three to six days.
A new ovum begins to mature in the ovaries.
Estrogen levels increase prompting the uterine lining to thicken.
Ovulation
Estrogen levels peek.
A mature ovum is released (Day 14).
Days 15 through 22
Ovum travels down the fallopian tube.
Egg may be fertilized at this time (unite with a sperm).
Day 22 to the beginning of next cycle
If egg is not fertilized, levels of both estrogen and progesterone will begin
to fall.
The uterine lining is shed as menstrual blood.
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Is there really such a thing as “PMS”?
A condition that describes the physical, psychological, and emotional symptoms related to a woman's menstrual cycle. Water retention Cramping Breast tenderness Backache Irritability Mood swings
Only 5% of women actually experience the emotional
symptoms of “PMS”.
Two reasons why the emotional symptoms of “PMS” are often over-reported:
1. Women are more likely to notice feelings of irritability when these moods
occur premenstrually.
2. Women label symptoms that occur before a period as “PMS”. Similar
symptoms at other times of the month are due to a stressful day.
Is there really such a thing as “PMS”?
- No gender differences exist in mood.
- No relation exists between stage of the
menstrual cycle and emotional symptoms. - No consistent “PMS” pattern exists across
successive menstrual cycles.
Why We Sleep
Sleep appears to function as a time-out period for the body: Waste products are eliminated. Cells are repaired. Immune system is strengthened. Hormone levels are maintained. Loss of One Night’s Sleep Decline in mental flexibility, attention, and creativity. Chronic Sleep Deprivation Impairment of brain cells necessary for learning and memory. The experience of hallucinations and delusions.
Trouble Sleeping?
Chronic Insomnia
Difficulty in falling or staying asleep. Occurs in 10% of adults. Causes of Chronic Insomnia Worry and anxiety. Psychological problems. Hot flashes during menopause. Physical problems (e.g., arthritis). Irregular or demanding schedule.
Sleep apnea
Sleep apnea Breathing briefly stops during sleep Individual momentarily awakens Causes of Sleep apnea Blockage of air passages Failure of the brain to control respiration properly
Trouble Sleeping?
Narcolepsy
Narcolepsy
Involves sudden and unpredictable daytime
attacks of sleepiness or lapses into REM sleep.
Affects 27, 000 Canadians.
Causes of Narcolepsy
Degeneration of neurons in the hypothalamus.
Genetic factors.
Most adults need at least 8 or 9 hours of sleep
Two-thirds of Americans get fewer than 7 or 8
hours.
Most students get only about 6 hours.
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