L5 & L6 | Thirst

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Questions and Answers

What does chronic tolerance to alcohol mean?

It takes more alcohol to produce the same effects after regular drinking. (correct)

The body metabolizes alcohol more slowly over time.

The body requires less alcohol to achieve the same effects.

Chronic tolerance can be maintained indefinitely without drinking.

Which of the following best describes the concept of 'disconnect' between behavior and blood alcohol concentration (BAC)?

Being unaware of one’s intoxication due to low BAC.

Feeling intoxicated despite a low BAC.

Feeling sober while having an elevated BAC. (correct)

Experiencing severe impairment without any alcohol consumption.

What is a common psychological impact of chronic alcohol use?

Increased tolerance to negative feedback about drinking.

Decreased need for alcohol to feel pleasure.

Improved social adjustment and emotional stability.

Preoccupation with alcohol leading to loss of control. (correct)

How does regular drinking affect the metabolism of alcohol in the body?

It alters the way cells respond to a given level of alcohol. Signup and view all the answers

What is a screening tool commonly used to identify potential alcohol addiction?

CAGE questions. Signup and view all the answers

What is one of the psychological effects attributed to alcohol consumption?

Euphoria Signup and view all the answers

Which brain system does alcohol primarily affect by increasing its permeability?

Nervous system Signup and view all the answers

Which of the following best describes the process of acute tolerance regarding alcohol?

Behavioral change decreases with increasing blood alcohol concentration Signup and view all the answers

What is the primary substance that alcohol is metabolized into within the body before further breakdown?

Acetaldehyde Signup and view all the answers

How does alcohol affect dopamine levels in the brain?

It increases dopamine levels Signup and view all the answers

Which of the following is a common result of alcohol abuse in terms of health outcomes?

Incidence of cirrhosis Signup and view all the answers

Which behavior is commonly associated with alcohol-induced aggression?

Heightened violent offenses Signup and view all the answers

What is a significant difference in the metabolism of alcohol between men and women?

Men metabolize alcohol faster due to more muscle mass Signup and view all the answers

Which condition is responsible for the highest number of deaths due to alcohol-related complications?

Cancers Signup and view all the answers

What is a common consequence of prolonged alcohol dependency?

Decreased brain plasticity Signup and view all the answers

Which factor contributes to the increased risk of binge drinking among Indigenous Australians compared to non-Indigenous Australians?

Higher rates of alcohol consumption Signup and view all the answers

During what process do the effects of alcohol on behavior change with continued exposure?

Increased tolerance Signup and view all the answers

How does alcohol influence reaction times according to research?

It lengthens reaction times Signup and view all the answers

Which of the following is a significant psychological effect of alcohol that can lead to dangerous situations?

Decreased inhibition Signup and view all the answers

What is one of the primary causes of Wernicke-Korsakoff syndrome?

Chronic alcohol abuse leading to low thiamine levels Signup and view all the answers

Which of the following symptoms is associated with delirium tremens?

Confusion and hallucinations Signup and view all the answers

What aspect of Korsakoff’s syndrome involves memory issues?

Anterograde amnesia Signup and view all the answers

Which neurodegenerative disorder is associated with degeneration of the corpus callosum?

Marchiafava-Bignami disease Signup and view all the answers

What is a common characteristic of fetal alcohol syndrome?

Facial abnormalities and developmental delays Signup and view all the answers

What effect does alcohol have on the metabolism of thiamine?

Inhibits thiamine metabolism and uptake Signup and view all the answers

Which condition is characterized by an inability to learn new information?

Korsakoff's syndrome Signup and view all the answers

What is a significant risk factor for developing alcoholism?

Genetic susceptibility from alcoholic parents Signup and view all the answers

What is the effect of Naltrexone in the treatment of alcoholism?

Prevents relapse by reducing craving Signup and view all the answers

How does severe alcohol dependence withdrawal manifest?

Severe tremors, convulsions, and hallucinations Signup and view all the answers

What effect does heavy drinking have on the risk of cancer?

Increases cancer risk, particularly in the mouth and esophagus Signup and view all the answers

What psychological condition is often comorbid with alcoholism?

Obsessive-compulsive disorder Signup and view all the answers

What physical condition can chronic alcoholism lead to?

Heart disease and cardiomyopathy Signup and view all the answers

Which of the following statements about tolerance to alcohol is true?

Developing tolerance can increase consumption and dependency risks. Signup and view all the answers

Study Notes

Thirst Based on Logue Ch. 3

97% of Earth's water is in the sea, with only 3% being fresh water
Fresh water resources are accessible, only about 0.7% of all water on Earth
It takes 3000 liters of water to produce the food a Westerner consumes in a day, with 400 liters per person for household use
This is not sustainable if everyone consumed at the current rate.

Water

Fresh water is an increasingly scarce resource
Water scarcity could become a basis for armed conflict, such as in the Middle East
Access to fresh water is a problem at the national and local level
3.5 billion people have access to piped water, while 1.4 billion do not have any supply,
Waterborne diseases, caused by contaminated water supplies, led to 0.5 million deaths in 2017

Extremes

Dehydration is a cause of death, most people between 15-25% bodyweight water deficit
Severe fatigue may occur at a 5-8% water deficit
Death typically follows at 10%

So what is Thirst?

Two kinds of thirst: homeostatic and non-homeostatic drinking
Homeostatic drinking: the body attempts to maintain a set point, and kicks in to regulate water consumption
Non-homeostatic drinking: anticipating future water needs

Homeostatic Drinking

Two main types of homeostatic drinking
1 part water for 1 part food in the stomach
3 parts water for 1 part food in the intestines

Blood, Plasma and Cells

Fluid in the body can be categorized into two compartments: inside and outside cells
Loss of fluid in either compartment can cause thirst
Example of fluid loss: increased salt in blood plasma draws water out of cells

Non-Homeostatic Drinking

Time, especially for animals that drink mostly at night
Anticipatory drinking: drinking while eating, even though not immediately needed from food consumption

Non-Homeostatic Drinking (2)

Schedule-induced polydipsia (SIP) is a particular form of non-homeostatic drinking, in which a rat's behaviour is shaped in such a way that will induce it to drink in excess amounts of water

Explaining Thirst

Three types of explanation for mechanisms underpinning thirst: central, peripheral, and combined mechanisms

Dry Mouth Theory

Walter Cannon's dry mouth theory
Thirst is caused by dryness in the mouth, which then triggers a peripheral response.
Saliva levels correlate with water deficit
If water is placed directly into the stomach, animals will still drink a roughly equivalent amount of water.

Evidence for Dry Mouth Theory

Saliva levels in the mouth correlate to water deficit
Mouth anesthetization alleviates thirst
Water placed directly into the stomach doesn't change the amount of water an animal drinks, it simply means the mouth must feel the water to cease thirst

Evidence Against Dry Mouth Theory

A man attempting suicide by cutting his throat to bypass mouth could still be very thirsty
Animals and humans can still drink normally even without salivary glands

Central Mechanisms

Hypothalamus (specifically the median preoptic nucleus) plays a role in detecting water deficit and initiating drinking behavior
Hypothalamus is sensitive to variations in salt levels and peripheral signals (e.g., vasodilation).
The hypothalamus controls the release of antidiuretic hormone (ADH), which increases water retention by the kidneys

Hypothalamus detecting water deficit

Specific cells in the hypothalamus are sensitive to variations in salt levels in blood plasma
Hypothalamus detects signals from peripheral sensors
It receives inputs from other sensory receptors outside the blood-brain barrier that monitor bodily systems

The Kidney

The kidney plays a role in regulating blood pressure and thirst
Arterial blood pressure falls during water deprivation
Kidney detects changes, releases renin

Blood pressure and thirst

Close link between blood pressure and thirst
Some groups appear more sensitive than others to angiotensin

Summary so far

Thirst is a complex interplay of peripheral and central mechanisms
These mechanisms involve departures from set points in related systems to induce thirst and drink

Explaining Non-Homeostatic Drinking

The capacity to move from one motivation to another is important in the natural environment
SIP arises from hunger, and the rat might temporarily change activities

Explaining NHD (2)

Anticipatory drinking occurs when we eat, as chemical changes occur when we see/smell food
Histamine and insulin release triggers drinking, and is released while eating.
Learning (e.g., desert nomads) can also influence drinking habits

Alcohol

Positive impacts: tax revenue, reducing cardiovascular deaths, preventing hospitalizations, and enabling some communal activities.
Negative impacts: alcohol-related harms including cirrhosis, heart disease, brain damage, road trauma, violent behavior, relationship breakdown, lost productivity, and increased rates of problematic drinking for various populations, particularly Indigenous Australians and women.

Alcohol Consumption

Over 90% of people aged 14+ in Australia have consumed alcohol
The consumption rate is relatively high (high)

Alcohol - Impact (2)

Annual rates of adverse health impacts in Australia (averaging over the decade) include conditions such as cancers, cardiovascular diseases, digestive diseases, injuries, and neuropsychiatric issues.
Alcohol abuse/misuse costs Australia billions of dollars annually

Effects of Alcohol on the Brain

Alcohol acts on multiple brain systems(similar to anesthetics)
Affecting nerve cell membranes, GABA receptors, levels of dopamine in the Nucleus Accumbens, and endogenous opioids
Affects brain levels differently across sexes (women less efficient at certain processes such as metabolism)

Tolerance

Behavioral and pharmacological effects of alcohol can change with exposure
Acute tolerance occurs during a drinking session
Chronic tolerance develops over time and is linked to regular drinking

Addiction to Alcohol

Addiction is described a chronic, progressive illness in which a person experiences a preoccupation and loss of control over alcohol consumption
Risk factors include genetic susceptibility, drinking culture.

Caffeine

Commonly consumed in a variety of products such as coffee, beverages, or food.
It is a psychoactive drug that is commonly consumed across the world

Psychological Effects

Decreases reaction time
Attentional and vigilance effects
Increases feelings of alertness and wellbeing in both sleep deprived and non-sleep deprived individuals

Is caffeine addictive?

There is a diagnosis, but little evidence of chronic tolerance and withdrawal
Few negative effects, yet widely consumed globally, especially in many beverage and food products.

Are such foods addictive?

It's debated whether certain foods are addictive, specifically highlighting hyper-processed foods
The implications of such claims on blame and legal ramifications, especially for food manufacturers

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