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Biological and learning psychology > Biology of fear, thermoregulation and eating behaviour > Flashcards

Biology of fear, thermoregulation and eating behaviour Flashcards

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1
Q

ADAPTIVE FUNCTIONS OF EMOTIONS

A

Fear → alerts us to escape from danger

Anger → directs us to attack an intruder

Disgust → tells us to avoid things that may cause illness

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2
Q

EMOTIONS PROVIDE USEFUL GUIDE IN:

A
  • making quick decisions &
  • understanding/communicating needs & probable
    actions
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3
Q

WHAT IS FEAR?

A
  • integral part of brain’s defensive mechanism
  • evolved to protect animals & humans from predation
    & other ecological threats
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4
Q

CLASSICAL FEAR CONDITIONING
TO STUDY EMOTION (LeDoux)

A
  • Fear conditioning is used as a behavioural
    measure of ‘fear’ that humans experience
  • Studies using lab rats & other mammals have
    helped map how the fear system of the brain
    works

Very old in evolutionary terms

  • Existed before humans experienced ‘fear’
  • To understand fear system, neuroscientists
    study underlying neural systems evolved as
    behavioural solutions to problems of survival
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5
Q

MANY COMMON PSYCHIATRIC DISORDERS ARE
‘EMOTIONAL’ DISORDERS:

A
  • many of these are related to the brain’s ‘fear system’

Public Health Service in US: ≈50% of ‘mental’ problems
(not related to substance abuse) are anxiety disorders:
* Phobias
* Panic attacks
* Post traumatic stress disorder
* Obsessive compulsive disorder
* Generalised anxiety

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6
Q

FEAR SYSTEM OF THE BRAIN

A

Pathways connecting emotional processing system of fear
(amygdala) with the thinking brain (neocortex) are not
symmetrical

Connections from neocortex → amygdala are much
weaker than those from amygdala → neocortex

This ‘double wiring’ creates problems in humans- we have
problems controlling our emotions:

  • once an emotion is aroused it is hard for us to turn it
    off at will and may explain why psychotherapy is a
    difficult & lengthy process
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7
Q

AMYGDALA (Dr Joseph LeDoux)

A

In humans a visual stimulus (e.g., snake on
path) travels to the amygdala in a few
thousandths of a second

HUMAN AMYGDALA CONTAINS CELLS THAT
FIRE IN RESPONSE TO:
* Expressions of fear on faces of other
humans
* Objects of fear

  • Most of the time the amygdala is quiet
  • Amygdala is designed to detect predators
  • A strong stimulus can result in:
  • Piloerection (hair standing on end)
  • Heart racing
  • Fight/flight hormones flooding body

Amygdala has connections to stimuli processing cortexes and forms associations between different stimuli for adaptive and conditioned learning.

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8
Q

EMOTION VS FEELING OF ‘FEAR’

A

Amygdala is specialised for reacting to stimuli &
triggering physiological response (i.e., emotion of
fear)

  • Different to conscious feeling of fear, which arises
    from slower 2nd pathway (ear→ amygdala
    →higher cortex)
  • Higher cortex analyses frightening stimulus in
    detail (using info from many parts of brain) &
    message is sent back down to amygdala
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9
Q

PHYSIOLOGY VS FEELING OF ‘FEAR’

A

‘FEAR’ IS USED SCIENTIFICALLY IN TWO WAYS:
* conscious feelings and
* behavioural and physiological responses.

Joseph LeDoux suggests that:
* ‘fear’ should denote feelings and
* ‘threat-induced defensive reactions’ should
be used for responses

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10
Q

EFFECTS OF FACIAL EXPRESSIONS ON AMYGDALA

A
  • response pattern of intracranial event-related
    potentials (ERPs) recorded from depth-electrodes in
    the human amygdala
  • Amygdala presented a preferential response to eyes
    expressing fear and joy- especially fear
  • special role of the amygdala in processing emotions
    conveyed by the eye region of the face
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11
Q

Amygdala and sound

A
  • If rats are threatened they emit very high
    frequency screams
  • If another rat hears this scream, a signal
    goes from auditory cortex (where sounds
    are processed) directly to amygdala
  • When these sound waves penetrate rat
    brain:
  • amygdala is instantly activated even though
    rat does not ‘know’ the sound is coming
    from another rat
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12
Q

ULTRASONIC RAT VOCALISATIONS (>ABOVE 20 KHz)

A
  • Infant distress calls: Infants cannot regulate their
    own body temperature & when they are cold they
    emit high pitched (40 kHz) distress calls
  • Long distress calls (20 kHz): when unhappy or
    stressed (e.g. when defeated socially, see a predator,
    experience/anticipate pain).
  • Short, chirping calls: higher pitched (50 kHz) &
    thought to be positive (e.g. during play, courtship, in
    anticipation of feeding, when tickled by personlaughter?)
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13
Q

AMYGDALA & OTHER EMOTIONS?

A
  • Amygdala has 12─15 distinct regions (only 2
    clearly implicated in fear)
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14
Q

AMYGDALA & MEMORY

A

For traumatic memory, two memory systems are
important:

  • EXPLICIT (CONSCIOUS) MEMORIES:
  • Mediated by hippocampus & other parts of
    temporal lobe memory system and
  • Blood pressure & heart rate rise, begin to sweat
    & muscles tighten up
  • IMPLICIT (UNCONSCIOUS) MEMORIES:
  • Mediated by amgydala & neural connections
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15
Q

anandamide

A

released by oxytocin and activates cannabinoid receptors to induce states of bliss.

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16
Q

Thermoregulation

A

Thermoregulation is the regulation of body temperature, usually within a specific range. In animals, there are two different types of thermoregulators: endotherms and ectotherms.

Animals are also either poikilotherms or homeotherms.

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17
Q

Endotherms

A

Endotherms can regulate their body temperature via metabolic processes. Endothermic animals can stay active in cold weather, but they need more energy to heat their bodies and therefore need more food. Maintain thermal
homeostasis irrespective of ambient temperature.

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18
Q

Ectotherms

A

Ectotherms have a body temperature that is influenced by the external environment (incorrectly known as ‘cold blooded’). Ectothermic animals do not need energy to heat themselves but as a result they are inactive in cold weather. Internal temperature
varies with ambient environmental temperature

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19
Q

Poikilotherms

A

Poikilotherms do not need a fixed body temperature to survive, and most terrestrial ectotherms are poikilotherms (e.g. snakes & many lizards) but the naked mole rat is a mammal poikilotherm.

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20
Q

Homeotherms

A

Homeotherms are animals that need to maintain a constant body temperature to survive and are usually endotherms (some ectotherms, e.g. desert lizards, are homeotherms).

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21
Q

THERMOREGULATION maintained with:

A
  • Insulation
  • Metabolic heat production/physiological
    thermoregulation
  • Countercurrent heat exchange
  • Behaviour
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22
Q

INSULATION

A
  • Fur (piloerection hair stands on end)
  • Feathers
  • Blubber
  • Colouration
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22
Q

PHYSIOLOGICAL THERMOREGULATION

A

Altering metabolic generation of heat to regulate
temperature
For example:
Metabolism increases to raise internal body
temperature in a colder environment

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23
Q

METABOLIC ACTIVITY

A
  • Shivering
  • Panting
  • Evaporation of water
    from respiration
    and/or sweating
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24
Q

COUNTERCURRENT HEAT EXCHANGE

A

Warm and cold blood flow in opposite directions
to regulate the temperature (arteries & veins)
* Usually around the brain/head region
* e.g. Leatherback Turtle, Sea Gull

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25
Q

BEHAVIOURAL THERMOREGULATION

A

Using posture, orientation and/or microclimate selection
to regulate body temperature
e.g. lizard increases temperature by “spread eagle”
posture on top of a hot rock (microclimate) & turning its
back to the sun (orientation)

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26
Q

TORPOR (mini-hibernation)

A

Reduced metabolic activity and body temperature for
less than a day (endotherm)- governed by circadian
rhythm
* Animals continue foraging
e.g. bats, hummingbirds, small Australian marsupials
(stripe-faced dunnarts)

27
Q

HIBERNATION

A

Long-term torpor (can be 6 months) occurring in the
winter months (endotherms & ectotherms), to
conserve energy
* animals usually do not forage but rely on energy
stores (food caches or body energy reserves)
e.g. European ground squirrels, adders, some bears

28
Q

ESTIVATION

A

Long-term torpor (can be 6 months) occurring in the
summer months (ectotherms)
* To avoid damage from high temperatures
(dessication-extreme dryness or drying out)
e.g. lungfish, salamanders, land snails, Australian
water-holding frog, cane toads

29
Q

OTHER BEHAVIOURS

A
  • Torpor, hibernation, estivation
  • Timing of activities
  • “Cooling off” techniques
30
Q

TIMING OF ACTIVITIES

A

NOCTURNAL–active at night
e.g. owl, mice, koala

DIURNAL–active during daytime
e.g. “grazers” –gazelles, elephants

CREPUSCULAR–active at dawn & dusk
e.g. deer, rabbits, most birds, red pandas, cats

CATHEMERAL –active at periods throughout 24-hours
e.g. some lemurs

31
Q

‘COOLING OFF’ TECHNIQUES

A
  • Rolling or wallowing in mud
  • Taking a “dip” or standing in the water
  • Going underground, using caves or lying in shade
  • Flying in high altitudes
32
Q

Biology of Thermoregulation
Focus on humans

A

Energy Balance: About 50%
used for Body Heat

37 degrees is optimal due to balance of hot enough that most fungi cannot survive for long in our body and cool enough that we do not need to spend most of our time consuming food to stay warm.

33
Q

BODY TEMPERATURE BALANCE IN HOMEOTHERMS

A
  • Metabolic heat production is usually required
    to maintain balance
  • Balance is very narrow range, usually higher
    than environment
  • Thermo neutral zone represents ambient
    conditions where heat gain by animal equals
    heat loss (= thermal comfort; 28-31 degrees C in naked
    humans)
34
Q

BODY TEMPERATURE BALANCE IN HUMANS

A

2 degree + Higher temperatures: temperature of the extremities close to the body core temperature

sweat evaporation and vascular dilation

2 degree - lower temperatures: vascular contriction

temperature of extremities falls

muscle contraction and shivering

35
Q

BODY TEMPERATURE BALANCE IN HOMEOTHERMS

A

Peripheral & body core receptors – sense change
HYPOTHALAMIC THERMOREGULATORY CENTER
integrates & initiates:
* Shivering
* non-shivering thermogenesis
* vasoconstriction

36
Q

THERMOREGULATION: PATHOLOGIES

A

HYPERTHERMIA: body temperature too high
Fever: pyrogens fight pathogens
Heat exhaustion (1020F/38.80C)
Heat stroke (1060F/410C) → death
Malignant hyperthermia – defective Ca++ release

HYPOTHERMIA: body temperature too low
Metabolism slows → loss of consciousness, death
Surgical applications: heart surgery

37
Q

THERMOREGULATION SUMMARY

A
  • Eatingprovides carbohydrates, proteins, & fats for
    metabolism
  • Energyis used for body heat & work: transport,
    synthesis, storage
  • Metabolic rate changes with age, sex, body fat,
    activity & diet
  • Insulin regulates anabolic cell activities & glucose
    uptake in cells
  • Maintaining homeothermy takes 50% of our
    energy
  • Hypothalamic thermoregulatory center controls
    heat homeostasis
38
Q

FEEDING STRATEGIES ACROSS SPECIES

A

REPTILES
* Eat a huge meal & sometimes don’t eat again
for weeks or months

BEARS THAT HIBERNATE
* Huge feasts, ‘fatten up’, periods of ‘starvation’

SMALL BIRDS
* Eat what they need & store almost no fat

HUMANS
* Eat more than we need
* Influenced by learned & unlearned mechanisms

39
Q

Human biological influences on eating behaviour

A

Hypothalamus sends cues to start or stop eating

Appetite hormones insulin, leptin, orexin, and ghrelin control eating and hunger

individual differences in basal metabolic rate

40
Q

Human socio-cultural influences on eating behaviour

A

Norms about appropriate body weight

culturally preferred and available foods

41
Q

Human psychological influences on eating behaviour

A

Sight and smell of food

Time elapsed since last meal

Individual differences in self-esteem, mood, and perfectionism

42
Q

HUMAN DIGESTIVE SYSTEM

A
  • Function of digestive system is to break food down
    into smaller molecules that cells can use
  • Glucose is the body’s main ‘fuel’
43
Q

ADULT PROBLEMS WITH MILK CONSUMPTION

A
  • Newborn mammals rely on mother’s milk
  • After weaning most mammals lose intestinal enzyme
    lactase ─ needed for metabolising lactose (sugar in milk)
  • In humans, about two thirds of adults have low levels
    lactase (recessive gene) & can eat small amounts dairy
    but then get cramps or ‘gas’
44
Q

TASTE & DIGESTION CONTROL HUNGER & SATIETY

A

ORAL FACTORS
* Humans like to eat: like to taste & chew even when not
hungry (e.g., chewing gum)

STOMACH & INTESTINES
* Main signal to stop eating is distention of stomach: stomach
sends satiety messages to brain via vagusnerve (info about
stretching stomach walls) & splanchnic nerves (info about
nutrient contents of stomach)

  • Also stop when duodenumpartly distended (part of small
    intestine adjoining stomach) & hormone cholecystokinin
    (CCK) limits meal size
45
Q

HUNGER: BODY CHEMISTRY

A

GLUCOSE
* form of sugar that circulates in the blood
* provides major source of energy for body tissues
* Insulin (a hormone) levels go up, glucose goes down
* when level is low, we feel hunger

SET POINT
* an individual’s natural level or “weight thermostat” for
weight regulation
* when the body falls below this weight, an increase in
hunger & a lowered metabolic rate may act to restore the
lost weight

BASAL METABOLIC RATE
* body’s base rate of energy expenditure

46
Q

HUNGER & THE BRAIN

A

The hypothalamus controls eating & other body
maintenance functions

monitors appetite hormone levels

47
Q

THE LATERAL HYPOTHALAMUS CONTROLS:

A
  • Insulin secretion
  • Alters taste responsiveness

Electrical stimulation of this area:
* Animal increases eating & food-seeking
behaviours

Damage to this area:
* Animal refuses food & water as if food distasteful
* Animal may starve to death if not force-fed

48
Q

VENTROMEDIAL HYPOTHALAMUS:

A
  • Tumors lead to overeating & weight gain
  • Alters taste responsiveness

Damage to areas in or around the ventromedial
hypothalamus:
* Animal has increased appetite, gains lot of
weight, then becomes ‘finicky’ eater
* Eat normal meals more often (overeat)

Damage to paraventricular nucleus of hypothalamus:
* Animal eats larger meals (overeats)

49
Q

Insulin

A

Hormone secreted by pancreas, controls blood sugar

50
Q

Leptin

A

Protein secreted by fat cells; when abundant, causes brain to increase metabolism and decrease hunger

51
Q

Orexin

A

Hunger triggering hormone secreted by hypothalamus

52
Q

Ghrelin

A

Hormone secreted by empty stomach; sends hungry signal to brain

53
Q

PYY

A

Digestive tract hormone; sends not hungry signal to brain

54
Q

EATING DISORDERS

A

OBESITY (considered medical condition)

ANOREXIA NERVOSA (considered psychiatric condition)
* Unwilling to eat as much as they need; become extremely
thin & may die

BULIMIA NERVOSA (considered psychiatric condition)
* Alternate between extreme dieting and binges of
overeating

EATING DISORDERS (ALL OF THEM)
* Include elements of biology(e.g., hunger) & psychology
(e.g., social factors, customs, advertising- think can eat
more if ‘low fat’, alcohol with meal increases calories)

55
Q

PSYCHOLOGY OF HUNGER

A

Factors other than biological ones influence
hunger & eating:
* Memories of last meal
* Taste preferences: cultural
* Social eating; trends; food security
* Cravings as a result of mood

56
Q

EFFECTS OF CULTURE & HABITS ON BODY WEIGHT

A

‘SETTLING POINT’: cluster of genetic &
environmental factors cause a person’s weight to
settle within a given range
* Children more likely to be obese if parents are
obese
* Weight can be affected by diet, exercise, daily
habits (e.g., use stairs instead of lift)

In the US, research based on 7-day diary of all
meals & circumstances showed:
* People eat more when with others than
alone
* Size of meal depends on time of day &
local customs (e.g. US have big meal at
night & small meal at lunch; France have
bigger meal at lunch & smaller meal at
night)
* People eat more on weekends, especially
Saturdays; when food is ‘low fat’, tastes
good & if drink alcohol with meal

57
Q

OBESITY IN MICE: LEPTIN?

A
  • Fat cells throughout body produce peptide
    leptin (more fat cells, more leptin)
  • Mice with ‘obese’ gene do not make leptin
  • Gene exists that increases eating, decreases
    metabolic rate & increases weight gain
58
Q

OBESITY IN HUMANS: LEPTIN?

A

Most obese people produce plenty of leptin & have
normal leptin receptors, so they overeat for other
reasons

59
Q

OBESITY IN AUSTRALIA

A

Heart Foundation of Australia:
* obesity & inactivity are 2 largest contributors to
developing heart disease– Australia’s biggest
killer

  • ≈ 55,000 people die from heart disease each year
    (1 every 12 minutes)
  • being active for at least 30 minutes a day reduces
    risk of heart disease
  • physical inactivity is a leading contributor to
    burden of chronic disease in Australia- estimated
    total cost to health budget of $1.5 billion
60
Q

Obesity has reached epidemic proportions globally

A

At least 2.8 million people die each year as a result of
being overweight (BMI> or =25) or obese (BMI>30);

In 1995 an estimated:
* 200 million obese adults worldwide
* 18 million under-five children overweight.

Since 2000:
* over 300 million obese adults
Once associated with high-income countries, obesity is
now also prevalent in low- and middle-income countries

61
Q

WORLD HEALTH ORGANIZATION:
CRISIS OF CHILDHOOD OBESITY

A

Commission on Ending Childhood Obesity
* In 2016, >41 million children under 5 years old
were overweight or obese.
* 70 million young children will be overweight or
obese by 2025 if current trends continue.
* The rate of increase is 30% higher in low- and
middle-income countries, than that of developed countries.

62
Q

RESEARCH ON WEIGHT REGULATION & DIETING

A
  • No consistent personality trait differences found
    between obese and non-obese people (e.g.,
    willpower, anxiety)
  • Dieters and obese are more likely to eat in
    response to stress than non-dieters
  • Family environment of little importance in
    determining body weight - genetics plays a large
    role
63
Q

PHYSIOLOGY OF OBESITY

A
  • Number of fat-storage cells is a major determinant of
    body weight
  • Fat cells are determined by genetics & food intake
  • They increase with weight gain, but merely shrink with
    weight loss - may stimulate hunger
  • Weight loss causes a decline in basal metabolism
64
Q

OBESITY & INACTIVITY

A

Obesity has been found to be more common
among those who watch the most television

65
Q

gut-brain connection (‘second brain’)

A

the gut microbiome produces neurotransmitters, such as, serotonin and dopamine in greater quantities than our brain, which means that we need to nurture our gut health to enhance our mental and physical wellbeing.

Biological and learning psychology (7 decks)

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