Chapter 4 Flashcards
Need
Any condition within the person that is essential and necessary for growth, well-being, and life
What happens when needs are nurtured and satisfied?
Growth occurs, life is maintained, and well being is enhanced
What happens when needs are neglected or frustrated?
Need’s thwarting will produce damage that disrupts biological or psychological well-beign
What do motivational states provide for needs?
The impetus to pursue growth and to act before damage occurs to psychological and bodily well-being
2 types of needs
Biological needs and psychological needs
3 types of biological needs
Thirst, hunger, sex
Where are biological needs inherent?
Within the workings of biological systems
3 types of psychological needs
Autonomy, competence, relatedness
Where are psychological needs inherent?
Within the strivings of human nature and healthy development
Thirst
Consciously experienced motivational state that readies the person to perform behaviours necessary to replenish a water deficit
Hunger
Hunger and eating involve a complex regulatory system of short-term (hormonal), long-term (fat cells), and environmental regulation
Sex
Sexual motivation rises and falls in response to a host of factors, including hormones, external stimulation, external cues (facial metrics), cognitive scripts, sexual schemas, and evolutionary process
Need-drive behaviour sequence
Satiated state
Physiological deprivation develops gradually
Prolonged physiological deprivation produces bodily need
Need intensifies; gives rise to psychological drive
Goal-directed motivated behaviour occurs as attempt to gratify drive
Consummatory behaviour occurs
Drive is reduced
What 7 core processes does the cyclical pattern depicting the rise and fall of psychological drive involve?
Biological need
Psychological drive
Homeostasis
Negative feedback
Multiple inputs/multiple outputs
Intra-organismic mechanisms
Environmental influences
What kind of variable can drive be considered?
Intervening variable
5 aspects related to thirst
Biological regulation
Thirst activation
Thirst satiety
Hypothalamus and kidneys
Environmental influences
Fluid homeostasis
Various fluid compartments in the body (2/3 of fluid is intracellular, 1/3 of fluid is extracellular)
What is volume of intracellular fluid regulated by?
Concentration of solutes in the interstitial fluids (Na = biggest factor)
What is fluid homeostasis normally?
Isotonic, meaning same osmotic pressure inside and outside a cell
Different ions on each side, but it balances out
Solute concentration
Tightly regulated
Na+ cannot cross membranes freely, so water moves to balance osmotic forces
High extracellular Na+: Water leaves cell
Low extracellular Na+: Water enters the cell
Control mechanisms for thirst
Solute concentration
Fluid volume
Solute concentration as a control mechanism
Kidneys and drinking regulate Na+ and water levels to maintain optimal solute concentration
Fluid volume as a control mechanism
Kidneys and drinking also maintains optimal vascular tone
Prevents high/low blood pressure
What 2 classes of receptors to monitor system of thirst?
Cell volume
Blood volume
2 correctional mechanisms
Ingestion/excretion of water
Ingestion/excretion of Na+
Excretion of water and Na+ is done by?
Kidneys
Ingestion of water and N mechanisms
Thirst and salt appetite
Kidneys
Deal with excess water and Na+
Maintains optimal conditions
Name and explain 2 main control mechanisms of kidneys
Aldosterone: secreted by adrenal cortex
Vasopressin (antidiuretic hormone): secreted by posterior pituitary
Levels of aldosterone
High = retain Na+
Low = excrete Na+
Levels of vasopressin
High = retain water
Low = excrete water
2 types of thirst
Osmotic thirst
Volumetric thirst
Osmotic thirst
Due to an increase in interstitial tonicity
Water leaves the cell and the cell shrinks
Occurs when there is a greater concentration of solutes outside the cell than inside
Volumetric thirst
Due to loss of extracellular volume
Bleeding, vomiting, diarrhea, edema
Both water and salt are lost from the extracellular space
No osmotic change, concentration of salt in extracellular fluid is the same, volume less
Increase of what leads to osmotic thirst? What happens next?
Increase in extracellular Na+
Water leaves intracellular space to balance osmotic forces
Kidneys kick into high gear to get rid of excess Na+ and excess extracellular water
Why is thirst initiated in osmotic thirst?
To correct imbalance
Where are the osmoreceptors?
How are they activated?
Circumventricular organs
Change in cell volume activates cells in these regions
What do the osmoreceptors induce?
VP release from posterior pituitary
Where are the 3 receptors for hypovolemia?
Kidneys
Baroreceptors in the heart
How do the kidneys act as a receptor for hypovolemia
Secrete renin in response to drop in blood volume
Renin converts angiotensin I into angiotensin II
5 ways angiotensin II corrects hypovolemia
Stimulates the adrenal cortex to secrete aldosterone: Preserves Na+
Stimulates the posterior pituitary to secrete VP: Preserves water
Increases blood pressure with vasoconstriction
Initiates thirst
Initiates salt appetite
How do the baroreceptors in the heart act as a receptor for hypovolemia
Detect pressure of returning venous blood
Low volume = low pressure
More blood = high volume = high pressure
Regulates fluid balance through innervation sent to brain
Satiety for water
To deal with an osmotic thirst challenge, it takes about 2-3 mins to consume the water you need
This water will start to enter your circulatory system in ~10-12 mins
Your ideal set point will be reached in about 40-45 mins
Drinking stops in anticipation of the need being met
You stop when you have enough water on board, but before the imbalance has been corrected
Are the mouth and throat implicated in the satiety mechanism?
Taste and swallowing contributes a little
Study: Thirsty rat preloaded with 14 mL of water by mouth or directly to stomach –> the stomach-preloaded group drinks more afterwards
Are stomach cues implicated in the satiety mechanism?
No
Pyloric cuff closes off pylorus
Stomach can’t empty
The animal will drink and the stomach can get quite distended, yet drinking persists
Is the duodenum implicated in the satiety mechanism?
Maybe, no good evidence, but it’s possible
Is the liver implicated in the satiety mechanism? How?
Yes, all nutrients collected in the stomach and intestines first pass through liver before getting distributed to the rest of the body
Inject water into portal vein –> thirsty rat stops drinking
Cut vagus nerve –> rat drinks more than expected
Environmental influences of thirst
Taste is rewarding - water becomes more hedonically positive with increased deprivation, sweet taste can cause overdrinking
Psychoactive components of drinks can be addictive (OH and caffeine)
Social and cultural influences can influence drinking
How does the CNS regulate energy and nutrients?
Energy and nutrients are vital to life –> can’t afford to run out
CNS anticipates needs and motivates behaviour to maintain the right amount of reserves: too little = risk running out; too much = risk being encumbered by reserves
CNS regulates energy and nutrient levels
CNS regulates eating and digestion
Energy usage
Large carbohydrate molecules are broken down into simple sugars
What is glucose? How is it stored?
Only fuel that brain can use
Stored in liver as glycogen
What does insulin signal?
To store glucose as glycogen
What does glucagon signal?
To mobilize glycogen as glucose
Mobilization of stored energy
NS can signal the release of energy from fat stores
White adipose gets sympathetic innervation
Denervation leads to an increase in number and size of fat cells
Stimulation of these inputs leads to breakdown of fat in adipose cells
Why is insulin needed?
To chaperone glucose into cells
Brain doesn’t need insulin, glucose freely enters neural tissue
Name the 3 phases of insulin regulation
Cephalic phase
Digestive phase
Absorptive phase
Cephalic phase of insulin regulation
Conditioned release triggered by food cues
Digestive phase of insulin regulation
Food in stomach and intestines triggers release of gut hormones, which trigger insulin release
Absorptive phase of insulin regulation
Glucodetectors in liver signal insulin release when glucose levels are high
Type 1 Diabetes
Child onset diabetes
Pancreas stops making insulin
High levels of circulating glucose, which can’t be stored
Type 2 Diabetes
Adult-onset diabetes
Cells become less sensitive/insensitive to insulin, or production of insulin decreases
Insulin as a feeding/satiety signal
Insulin release is related to circulating glucose and is part of the signal to start/stop eating
High insulin
Lots of glucose, stop eating
Low insulin
Little glucose, be hungry
What happens when a little insulin is injected into an animal?
Feeding will stop
What happens when insulin is blocked in an animal?
Animal will start eating
What happens when a lot of insulin is injected into an animal?
Glucose is moved into liver and stored, so blood levels of glucose drop, and eating resumes
Is circulating glucose a signal to stop/start eating?
Presence of glucose should turn off hunger, and absence should activate it
Hypoglycemia is associated with hunger
Explain diabetic rats in relation to circulating glucose
Diabetic rats have low insulin and high glucose and are chronically hungry
But if they are fed a high fat diet, they eat a normal amount; can make immediate use of fatty acids without use of insulin
Hypothalamic regulation of hunger
Key to regulating hunger
Complicated system with many redundancies
Old hypothesis about the hypothalamic regulation of hunger
Dual-centre
Motivated state was a balance between the hunger centre (lateral hypothalamus) and the satiety centre (ventromedial hypothalamus)
What centre is the paraventricular nucleus?
Satiety centre
What kind of centre is the arcuate nucleus?
Main hunger centre
Set point theory test
Does lesioning the MNH or LH just change the set point?
Starve animal before LH lesion
Overfeed animal before VMH lesion
Should have little or no effect on these rats because they are already at the new set-point
What does the study on the set point theory tell us?
There is no one hunger centre
Peripheral signals: Leptin
Produced by fat cells
Levels are proportional to body fat: acts as an off switch
Mouse model on leptin
Human relation?
Defective leptin gene
Give them leptin, reduces obesity
Small minority of morbidly obese people have a defective leptin gene
Peripheral signals: Ghrelin
Released into bloodstream by endocrine cells in the stomach
Appetite stimulant
Levels rise during fasting and drop after a meal
Ghrelin and obesity
In obesity, ghrelin levels don’t drop after eating –> keeps stimulating appetite
Obesity
Increased body weight that is of sufficient magnitude to produce averse health consequences
Examples of adverse health consequences caused by obesity
Heart disease, stroke, type 2 diabetes, premature death, some cancers
Epigenetics of obesity
70% genetic, 30% behavioural-environmental
Which provinces have the highest prevalence of obesity?
NB and NL
What might GLP-1 receptor agonists play a role in?
Regulating motivation and emotional states
Negative impacts of GLP-1 receptors agonists
Cases of increased anxiety or worsening mood
What can weight loss success enhance?
Feelings of competence and increasing self-efficacy
What can weight loss success deepen? Caveat?
Intrinsic motivation to maintain a healthy lifestyle
However, if motivation becomes too reliant on external factors (medication, social validation, appearance concerns) intrinsic motivation may weaken over time
What effects do medications like Ozempic mimic?
Glucagon-like peptide-1 (GLP-1)
Where is GLP-1 produced?
In the intestines
Name 4 things GLP-1 plays a key role in
Stimulating insulin release
Inhibiting glucagon release
Slowing gastric emptying
Appetite regulation
Stimulating insulin release
GLP-1 helps regulate blood sugar by stimulating insulin secretion from the pancreas when blood sugar levels are elevated
Inhibiting glucagon release
GLP-1 agonists inhibit the release of glucagon, a hormone that raises blood sugar levels
Slowing gastric emptying
Ozempic slows the rate at which food moves through the stomach, which helps you feel full for longer periods
Appetite regulation
Ozempic also impacts areas of the brain responsible for hunger
It promotes a feeling of satiety, making it easier to reduce calorie intake
Name 3 reasons why weight loss is so hard?
Counterforce to caloric restriction
Counterforce to caloric burn
Counterforce to caloric restriction through environmental events
Counterforce to caloric restriction
When the body detects caloric restriction, it releases ghrelin into the bloodstream, a potent hunger-stimulating hormone that puts pressure on the person to eat
Counterforce to caloric burn
When a person exercises vigorously, they often compensate for that caloric burn by eating something extra and decrease the extent of their physical activity for the rest of the day
Counterforce to caloric restriction through environmental events
Many stimulate eating - the easy availability, accessibility, affordability, and advertising to promote high caloric foods
5 processes involved in sex
Physiological regulation
Facial metrics
Sexual scripts
Sexual orientation
Evolutionary basis of sexual motivation
Physiological regulation of sex
Sex hormones, gender differences in strength of sex drive, brain’s reward circuitry
Sexual scripts
How we rehearse sexual encounters in our brains
Men: Sexually attractive person - arousal builds
Women: Intimacy is important
Evolutionary basis of sexual motivation
Men: Physical characteristics, attractiveness
Women: Status, ability to provide
Traditional sex response cycle in men
Desire
Arousal
Orgasm
Resolution
Alternative sex response cycle in women
Intimacy needs
Being open and receptive to sexual stimuli
Arousal
Desire
Enhanced intimacy
3 reasons people fail at self-regulation of biological needs
People routinely underestimate how powerful a motivational force biological urges can be when they are not currently experiencing them
People can lack standards, or they have inconsistent, conflicting, unrealistic, or inappropriate standards
People fail to monitor what they are doing as they become distracted, preoccupied, overwhelmed, or intoxicated
