Temperature Regulation, Homeostasis, Thirst, Hunger, and Eating Disorders

106 QUESTION_AND_ANSWER flashcards covering temperature regulation, thirst, hunger, digestion, and eating disorders.

What is temperature regulation?

A vital biological process that maintains internal body temperature to support normal behavior and physiological function.

What is homeostasis?

The biological process that maintains internal variables like temperature, water, and glucose within a fixed range.

What is allostasis?

The adaptive process the body uses to anticipate future needs and adjust physiological systems accordingly.

What is a set point in physiology?

A single value the body works to maintain, such as water, oxygen, or glucose levels.

What is negative feedback?

A process that reduces discrepancies from the set point to maintain homeostasis.

What is basal metabolism?

The energy used to maintain a constant body temperature while at rest.

How much energy does temperature regulation require compared to other bodily activities?

About twice as much as all other bodily activities combined.

What does poikilothermic (ectothermic) mean?

Body temperature matches the environment; found in amphibians, reptiles, and most fish.

How do poikilothermic animals regulate their body temperature?

Through behavioral methods such as choosing warmer or cooler environments.

What does homeothermic (endothermic) mean?

Maintaining a constant internal body temperature via physiological mechanisms.

How do mammals cool themselves when overheating?

By sweating or panting.

How do mammals warm themselves when cold?

By shivering and restricting blood flow to the skin.

How can poikilotherms survive in cold environments?

By burrowing underground or using antifreeze compounds in their blood.

What is the evolutionary advantage of a 37°C body temperature in mammals?

It optimizes muscle activity and keeps the body ready for vigorous movement.

What limits mammals from having an even higher body temperature?

Protein breakdown and the sensitivity of reproductive cells.

Which brain area regulates body temperature?

The preoptic area/anterior hypothalamus (POA/AH).

How does the POA/AH control body temperature?

It receives input from temperature and immune receptors and triggers responses like sweating or shivering.

What chemicals does the immune system release during illness to affect temperature?

Prostaglandins and histamines.

What effect do prostaglandins and histamines have on body temperature?

They cause fever, shivering, and increased metabolism.

What is fever?

An increased body temperature set point, initiated by the hypothalamus.

Why can moderate fever be beneficial?

It slows bacterial growth and enhances immune function.

At what temperature is fever considered dangerous?

Above 39°C (103°F) it's harmful; above 41°C (109°F) it's life-threatening.

Approximately what percentage of a mammal’s body is water?

About 70%.

Why is water regulation crucial for the body?

Because chemical reactions depend on proper fluid balance.

How can the body conserve water when needed?

By producing concentrated urine and reducing sweating.

What is vasopressin?

A hormone released by the posterior pituitary that helps retain water and constrict blood vessels.

What is another name for vasopressin?

Antidiuretic hormone (ADH).

What are the two main types of thirst?

Osmotic thirst and hypovolemic thirst.

What typically causes osmotic thirst?

Eating salty foods, which increases solute concentration outside cells.

What is osmotic pressure?

The movement of water across a membrane from low to high solute concentration.

Which brain areas detect osmotic pressure?

Receptors around the third ventricle, including the OVLT and subfornical organ.

What is the OVLT (organum vasculosum laminae terminalis)?

A brain structure that detects sodium content and osmotic pressure.

What is the function of the supraoptic nucleus regarding water balance?

It controls vasopressin release from the posterior pituitary.

What happens behaviorally when osmotic thirst is triggered?

The individual drinks water, which is absorbed and reaches the brain in about 15 minutes.

How is thirst inhibited after drinking?

By monitoring swallowing and stomach distension.

What is hypovolemic thirst?

Thirst resulting from fluid loss (bleeding, sweating) rather than increased salt concentration.

Which hormones respond to hypovolemic thirst?

Vasopressin and angiotensin II.

What does angiotensin II do in the brain?

It stimulates areas near the third ventricle and acts as a neurotransmitter in the hypothalamus to encourage drinking.

What kind of water do animals with osmotic thirst prefer?

Pure water.

What kind of water do animals with hypovolemic thirst prefer?

Slightly salty water.

What is sodium-specific hunger?

A strong craving for salty foods to restore solute balance.

How do predators and birds differ in feeding strategies?

Predators eat large meals infrequently, whereas birds eat small amounts often.

Where does digestion begin?

In the mouth with enzymes in saliva.

What is the main digestive role of the stomach?

It uses hydrochloric acid and enzymes to digest proteins.

What is the primary function of the small intestine?

To digest proteins, fats, and carbohydrates and absorb nutrients into the bloodstream.

What does the large intestine do?

Absorbs water and minerals and passes waste as feces.

What is lactose?

A sugar found in milk.

What is lactase?

The enzyme required to digest lactose.

What happens when adults lack lactase?

They experience gas and cramps from consuming dairy products.

Why do many adults in East Asia have lactose intolerance?

Because they lack the gene to produce lactase beyond childhood.

Name one common food selection myth.

Examples include: sugar causes hyperactivity, turkey makes you sleepy, fish is brain food.

What is a short-term strategy animals use for food selection?

Taste preference and aversion to previously harmful foods.

Beyond taste, what controls food selection?

Digestive feedback and conditioned learning.

Which brain area is important for taste-aversion learning?

The insular cortex.

What is the duodenum?

The first part of the small intestine that can signal satiety via hormone release.

What hormone does the duodenum release to promote satiety?

Cholecystokinin (CCK).

How does CCK help stop a meal?

It closes the sphincter from stomach to duodenum and stimulates the vagus nerve, causing stomach distension signals.

What information does the vagus nerve convey related to eating?

Stomach stretch information to the brain.

What information does the splanchnic nerve carry?

Details about the nutrient content of the stomach.

What is insulin’s primary role in metabolism?

To help glucose enter cells and signal satiety.

What is glucagon’s role in energy balance?

It promotes conversion of stored energy back to glucose.

What effect do high insulin levels have on hunger?

They increase hunger as glucose quickly enters cells, lowering blood sugar.

What condition results from consistently low insulin levels?

Type I diabetes, where glucose stays in the blood and causes hunger.

What is leptin?

A hormone produced by fat cells to signal satiety and regulate fat storage.

What happens to leptin levels when body fat increases?

Leptin increases, signaling the brain to reduce hunger.

What occurs when leptin levels are low?

Increased hunger and reduced physical activity.

What is ghrelin?

A hormone released by the stomach that increases appetite.

How do ghrelin levels change around meals?

They rise before meals to signal hunger.

What effect does ghrelin have in the brain?

It binds to hypothalamic receptors to stimulate eating.

What is the arcuate nucleus of the hypothalamus?

A key area for integrating hunger and satiety signals.

What are the two types of neurons in the arcuate nucleus?

One set sensitive to hunger signals and another to satiety signals.

Which signals activate hunger neurons in the arcuate nucleus?

Ghrelin, taste input, and low leptin/insulin levels.

Which signals activate satiety neurons in the arcuate nucleus?

Leptin, insulin, and CCK.

What is the role of the paraventricular nucleus (PVN)?

It receives input from the arcuate nucleus and inhibits the lateral hypothalamus to regulate meal size.

Which neurotransmitter inhibits the PVN and increases meal size?

Neuropeptide Y (NPY).

What roles do agouti-related peptide (AgRP) and GABA play in feeding?

They inhibit PVN activity and promote feeding.

What does melanocortin do in appetite regulation?

It excites the PVN to inhibit eating.

What is the effect of PVN damage?

Increased meal size.

What is the function of the lateral hypothalamus?

It promotes feeding behavior and detects hunger signals.

What happens if the lateral hypothalamus is damaged?

Animals refuse food and water.

What happens when the lateral hypothalamus is stimulated?

Eating and food-seeking behavior increase.

Name two processes the lateral hypothalamus influences.

Taste responsiveness, arousal, insulin secretion, and digestive secretions (any two).

What is the ventromedial hypothalamus (VMH)?

A brain region that inhibits feeding.

What are the effects of VMH damage?

Frequent small meals, increased insulin levels, and fat storage.

Does VMH damage cause constant eating?

No; it increases meal frequency, not necessarily overall size.

What does paraventricular inhibition lead to regarding meals?

Increased meal size.

List two major causes of obesity.

Genetics, environment, low activity level, early feeding habits (any two).

Name one gene associated with obesity.

Mutations in the leptin gene or melanocortin receptors.

What does the melanocortin receptor normally signal?

Satiety; mutations can lead to overeating.

Give one environmental factor that increases obesity risk.

Sedentary lifestyle or easy access to high-calorie foods.

What is syndromal obesity?

Obesity associated with a medical condition or genetic disorder.

What is monogenic obesity?

Obesity caused by mutation in a single gene, such as the leptin gene.

What is polygenic (common) obesity?

Obesity involving many genes each contributing small effects.

What are leptin levels like in most obese individuals?

High, but with reduced leptin sensitivity.

Name one treatment that can reduce leptin resistance.

Diet, exercise, or certain medications.

What is bariatric surgery?

Surgical intervention to reduce stomach size or nutrient absorption.

What does Roux-en-Y gastric bypass surgery do?

It shrinks the stomach and bypasses part of the small intestine.

Which eating disorder involves extreme dieting and weight loss?

Anorexia nervosa.

Which eating disorder involves bingeing and purging?

Bulimia nervosa.

What biological change is associated with bulimia?

Increased ghrelin levels and altered dopamine response to food.