Physiological Psychology (Midterms)

Homeostasis

The maintenance of a constant internal environment in response to a changing external environment, involving hormones made of proteins released by glands to target cells.

Control System in Homeostasis

A system that brings the body back to a constant equilibrium using negative and positive feedback loops involving the nervous and endocrine systems.

Positive Feedback Loop

A feedback system that amplifies a change.

Negative Feedback Loop

A feedback system that reverses a change to maintain stability.

Components of Homeostasis

Receptors, the control center, and the effector, which work together to maintain balance.

Maintaining Homeostasis

The body’s ability to adjust physiological processes to maintain a stable internal balance or equilibrium.

Drive States

Tension and discomfort generated by the nervous system to motivate behavior when homeostasis is compromised, such as thirst or hunger.

Set Points

Specific values that the body actively defends, like temperature, fluid levels, and weight.

Hormones

Chemical substances made of proteins, released by glands into the bloodstream to reach target cells and bring about changes in the cell.

Regulation of Body Temperature

A homeostatic process that involves maintaining a set point, detecting deviations, and using internal and behavioral methods to regain the set point.

Importance of Temperature Regulation

Necessary to prevent damage to cells, as low temperatures can cause ice crystal formation and high temperatures can destabilize proteins.

Endotherms

Animals (like mammals and birds) that maintain body temperature through internal metabolic activity.

Ectotherms

Animals (like amphibians, reptiles, and fish) that regulate body temperature through external factors, such as basking in the sun or seeking shade.

Surface-to-Volume Ratio

The relationship between the surface area and volume of an animal’s body, affecting heat production and loss. Smaller animals with higher ____ lose heat faster.

Adaptations to Cold Climates

Animals tend to have compact, stocky bodies with short appendages to reduce surface area and heat loss.

Adaptations to Warm Climates

Animals typically have slim bodies and long appendages to increase surface area and promote heat loss.

Behavioral Responses to Heat and Cold

Actions taken by endotherms and ectotherms to regulate body temperature, such as moving to a warmer or cooler environment, changing body position, and modifying social behavior.

Ectotherms' Temperature Regulation

Rely on behavioral strategies to regulate temperature, as they lack internal mechanisms. Examples include basking in the sun or seeking shade.

Endotherms' Temperature Regulation

Use both behavioral and internal physiological responses to maintain a set body temperature.

Behavioral Adjustments to Temperature

Includes stretching out to increase surface area when hot or curling up to minimize exposure when cold. Social animals may huddle for warmth.

Seasonal Fur Changes

Animals alter fur weight, color, and composition in response to temperature changes. Humans use clothing for similar purposes.

Dens and Nests

Structures animals use to protect themselves from temperature changes.

Shivering

Involuntary muscle twitches producing heat when internal temperature drops below the set point (98.6°F/37°C), though energy-intensive.

Blood Vessel Constriction

A response to cold, reducing blood flow to the skin to minimize heat loss, which may lead to Raynaud's disease if overly constrictive.

Raynaud's Disease

A condition where arteries (especially in fingers and toes) undergo spasms in response to cold, leading to numbness and a white appearance.

Thyroid Response to Cold

The thyroid gland releases more hormones to increase metabolic activity, producing warmth during prolonged cold exposure.

Brown Fat Cells

Specialized cells that generate heat through metabolic activity, particularly in infants and small animals, stimulated by the sympathetic nervous system.

Core Body Temperature

The temperature maintained for vital organs within the head and torso, with significant deviations posing health risks.

Hot Flashes

Sudden warmth, sweating, and palpitations experienced by some women around menopause, likely due to hormonal changes.

Factors Increasing Hot Flashes

Daily alcohol consumption can increase the frequency and severity of hot flashes during menopause.

Brain Mechanisms for Temperature Regulation

A structural hierarchy responsible for temperature control, from the spinal cord to the brainstem and hypothalamus. Sensitivity to temperature change increases at higher levels.

Spinal Cord Temperature Regulation

Reacts to temperature changes only when core temperature deviates by 2-3 degrees from the set point.

Hypothalamus Temperature Sensitivity

Acts as a precise thermostat, compensating for temperature deviations as small as 0.01 degrees from the set point.

Thirst Regulation

The body's process of maintaining fluid balance, essential for survival, especially as animals adapted to land from the ocean.

Solutes

Molecules dissolved in a fluid.

Electrolytes

Solutes that break into ions and dissolve.

Sodium (Electrolyte)

The most important electrolyte for managing the body’s fluid levels.

Intracellular Fluid

Fluid within cells, comprising about two-thirds of the body's total water.

Extracellular Fluid

Fluid outside cells, including blood plasma (7% of total body water) and interstitial fluid (26% of total body water).

Cerebrospinal Fluid

A small component of extracellular fluid found in the brain and spinal cord.

Composition of Intracellular Fluids

Has higher concentrations of potassium

Composition of Extracellular Fluids

Has higher concentrations of sodium and chloride

Isotonic Solutions

Solutions with equal concentrations of solutes, preventing the need for adjustments between intracellular and extracellular fluids.

Intravenous (IV) Fluids

Typically isotonic solutions containing sugars and sodium, matching the concentration of normal body fluids for safe absorption.

Kidneys

Organs located in the lower back that filter blood, removing excess sodium and water through nephrons and excreting waste as urine.

Nephrons

Over a million structures in the kidneys that filter blood, remove impurities, and send excess water and sodium to the bladder for excretion.

Kidney Dialysis

A medical procedure that replicates the filtering function of the kidneys when they fail, using a machine to filter the blood.

Evaporation

The process of losing water through respiration, such as when breathing out moisture on a cold day.

Perspiration

The loss of about 1 liter of fluid per day through sweating.

Defecation

The process of losing water through the elimination of waste in the form of feces.

Daily Water Intake

Humans need an average of about 2.5 liters (0.55 gallons) of water per day, including fluids obtained from food.

Osmotic Thirst

Thirst that occurs in response to cellular dehydration, usually caused by a decrease in intracellular fluid volume.

Hypovolemic Thirst

Thirst that occurs due to a decrease in blood volume, often caused by blood loss or dehydration.

Double-Depletion Hypothesis

The idea that both osmotic and hypovolemic thirst contribute to the sensation of thirst, with osmotic thirst being the more common mechanism.

Hypertonic

A condition in which the blood becomes more concentrated with sodium, making it have a higher solute concentration than the intracellular fluid.

Isotonic

Two solutions with equal concentrations of solutes, such as the balance between extracellular and intracellular fluids in the body.

Polydipsia

Excessive drinking of fluids, often caused by conditions like untreated diabetes mellitus.

Antidiuretic Hormone (ADH)

A hormone released by the posterior pituitary gland that signals the kidneys to reduce urine production and retain water.

Renin

A hormone released by the kidneys that triggers the conversion of angiotensinogen into angiotensin II, which helps regulate blood pressure and sodium retention.

Angiotensin II

A biologically active hormone that constricts blood vessels to help maintain blood pressure and triggers the release of aldosterone.

Aldosterone

A hormone released by the adrenal glands that signals the kidneys to retain sodium to maintain extracellular fluid balance.

Subfornical Organ (SFO)

A structure in the brain that responds to angiotensin II and triggers drinking behavior when activated.

Median Preoptic Nucleus

A brain region that receives input from the SFO and helps initiate drinking behavior.

Zona Incerta

A brain structure that sends information to motor regions, including the basal ganglia, to produce drinking behavior.

Cessation of Drinking

The process of stopping drinking when the body senses it has enough fluid, typically before normal fluid levels are fully restored. Fluid receptors in the mouth, throat, and digestive system help signal the stopping point.

Septal Area

A brain structure involved in the cessation of drinking. Lesions to this area lead to overdrinking, suggesting it plays a role in signaling when to stop drinking.

Hyponatremia

A condition where extracellular sodium levels drop more than 10% below average, often caused by overdrinking water. Symptoms include nausea, vomiting, cramps, disorientation, and, in severe cases, seizures, coma, and death.

Extreme Endurance Events

Activities that have led to an increase in cases of hyponatremia due to excessive water consumption during prolonged physical exertion.

Hunger

The body's drive to obtain and consume food, regulated by physiological mechanisms but influenced by emotions, learning, and cultural factors.

Eating Disorders

Conditions such as obesity and anorexia nervosa that arise when complex cultural and psychological factors disrupt the body's natural eating behaviors.

Obesity

A psychological and physiological condition characterized by excessive body fat, often influenced by factors such as overeating, lack of physical activity, and cultural or emotional triggers. It can lead to health issues such as heart disease, diabetes, and hypertension.

Anorexia Nervosa

An eating disorder marked by an intense fear of gaining weight and a distorted body image, leading to severe restriction of food intake. Individuals with anorexia nervosa often have a dangerously low body weight and may experience malnutrition and other serious health complications.

Lactose Intolerance

A condition in which individuals lack the enzymes necessary to process dairy products after infancy. This is more common in Asian populations, where dairy consumption is low. In contrast, lactose intolerance is rare in Scandinavian countries and parts of the Middle East, where dairy consumption has been historically high.

Learned Food Preferences

Can begin early in life, influenced by exposure to flavors through amniotic fluid. For example, pregnant women consuming carrot juice led to their infants showing a preference for cereal made with carrot juice.

Glucagon

A hormone produced by the pancreas that converts glycogen back into glucose, helping to maintain blood glucose levels during periods when the body taps into its glycogen stores.

Insulin

A hormone produced by the pancreas that helps regulate blood glucose levels by allowing glucose to move from the blood into cells, where it is used for energy or stored as glycogen.

Type 1 Diabetes Mellitus

A form of diabetes typically diagnosed in childhood or adolescence, where the immune system destroys insulin-producing pancreatic cells, leading to a lack of insulin and high blood glucose levels.

Type 2 Diabetes Mellitus

A form of diabetes where the body either does not produce enough insulin or does not use it efficiently, often due to insulin resistance. It can often be prevented or treated through maintaining a healthy weight, but obesity is a significant risk factor.

Fructose

An inexpensive sweetener commonly used in processed foods. Excessive consumption of fructose can lead to insulin resistance and pre-diabetic conditions, contributing to the development of Type 2 diabetes.

External Cues for Eating

Factors outside of the body, such as the time of day, the sight and smell of food, or the social environment, that trigger feelings of hunger and eating behavior, often leading to overeating or eating when not hungry.

Internal Cues for Eating

Signals generated by the body when nutrients are lacking, such as the sensation of hunger or stomach rumbling, indicating a need for food. However, hunger can also occur due to other factors beyond just an empty stomach.

Blood Glucose and Hunger

Hunger is influenced by blood glucose levels; as glucose levels drop, hunger signals are triggered. Insulin plays a role in regulating glucose and, by extension, hunger, but insulin injections and diabetes can lead to hunger despite high glucose levels in the blood.

Glucoreceptors

Receptors in the brainstem and liver that detect glucose and fatty acid levels in the body. They communicate with the brain, particularly the hypothalamus, to regulate hunger and initiate feeding behavior.

Lateral Hypothalamus (LH)

A brain region previously thought to act as a "hunger center." Lesions in the ___ can cause animals to stop eating and starve, while stimulation of the ___ can immediately trigger feeding behaviors.

Leptin

A neurochemical produced by fat cells that regulates feeding behavior. When fat stores are low, leptin levels are low. Obese humans often produce large amounts of leptin but are resistant to its effects, making it ineffective for weight loss.

Satiety

The feeling of fullness that signals when to stop eating. Satiety is influenced by both internal cues (like stomach fullness) and external cues (such as time or social settings). The obesity epidemic demonstrates how people can override their internal satiety cues.

Duodenum

The part of the small intestine that connects with the stomach and is involved in signaling satiety. When glucoreceptors in the duodenum sense sugar, eating typically stops. The ____ also releases cholecystokinin (CCK), which plays a role in promoting satiety.

Cholecystokinin (CCK)

A peptide released in the duodenum that signals satiety. It promotes insulin release, helps break down fats by contracting the gallbladder to release bile, and functions as a neurotransmitter related to satiety in the brain.

Ventromedial Hypothalamus (VMH)

A brain region thought to serve as a satiety center. Lesions in the this part in rats result in excessive weight gain and altered eating behaviors, including picky eating and reduced intake when food is mixed with a bitter substance.

Alpha-Melanocyte-Stimulating Hormone (AMSH)

A neuropeptide released by neurons in the arcuate nucleus in response to high levels of leptin. It increases metabolic rate by activating the autonomic nervous system and inhibiting feeding behavior.

Cocaine- and Amphetamine-Regulated Transcript (CART)

Another neuropeptide released in response to high leptin levels. Like AMSH, this neuropeptide increases metabolism, body temperature, and inhibits feeding behavior, contributing to the regulation of satiety.

Body Max Index (BMI)

A calculation used to determine healthy body weight by dividing a person’s weight (in kg) by the square of their height (in meters).

Healthy

A BMI between 18.5 and 24.9 is considered as ______.

Overweight

A BMI above 25 indicates _____.

Obese

A BMI of 30 to 39.9 is _____.

Morbidly Obese

BMI of 40 or more is ______.

Caloric Restriction

Animal studies suggest that ______ promotes longer lifespans and healthier aging.

Genetics, lifestyle, social factors, and environmental stressors

Obesity risk factors

Bulimia Nervosa

Characterized by cycles of binge eating followed by purging (vomiting or laxative use). It affects 3% of the population and leads to symptoms like fatigue, headaches, and dental enamel loss. It’s more common than anorexia, with some individuals having both disorders.

Environmental Factors of Eating Disorders

Exposure to thin ideals, such as models and actresses, plays a significant role in the development of eating disorders. Models today are significantly thinner than the average woman, leading to societal pressure on body image.