Temperature Regulation and Thirst Mechanisms in Biology

Homeostasis

Biological process maintaining stable internal conditions.

Allostasis

Adaptive regulation anticipating needs based on situations.

Set Point

Target value body maintains for specific variables.

Negative Feedback

Processes reducing deviations from the set point.

Basal Metabolism

Energy expenditure for maintaining body temperature at rest.

Brown Adipose Cells

Cells generating heat through metabolism, not contractions.

Ectothermic

Dependence on external heat sources for body temperature.

Poikilothermic

Animals lacking physiological temperature regulation mechanisms.

Endothermic

Ability to generate internal heat to maintain temperature.

Homeothermic

Animals maintaining body temperature significantly above environment.

Cooling Mechanisms

Processes like sweating and panting to reduce body heat.

Heating Mechanisms

Processes like shivering and fluffing to increase body heat.

Behavioral Regulation

Actions like changing clothing or seeking shelter for temperature control.

Surviving Extreme Cold

Strategies to maintain temperature below freezing conditions.

Glycerol in Blood

Substance used by some animals to survive winter.

Fluid Withdrawal

Storing fluids in extracellular spaces to prevent freezing.

Blood Clotting Capacity

Ability to quickly repair ruptured blood vessels.

Energy for Temperature Maintenance

⅔ of total energy spent on body temperature regulation.

Physiological Mechanisms

Biological functions maintaining constant core temperature.

Heat Generation

Proportional to mass; heat radiation proportional to surface area.

Behavioral Temperature Regulation

Actions taken to adjust body temperature in response to environment.

Disturbance Relief

Behavioral response to restore balance after a disturbance.

Thermophiles

Organisms that thrive in extreme heat.

POA/AH

Preoptic area/anterior hypothalamus regulating temperature.

Fever

Increased body temperature set point by hypothalamus.

Prostaglandins

Compounds causing fever and increased metabolism.

Histamines

Substances released during immune responses, causing shivering.

Vasopressin

Hormone regulating water retention and blood pressure.

Osmotic Thirst

Thirst triggered by high solute concentration.

Hypovolemic Thirst

Thirst due to loss of blood volume.

Osmotic Pressure

Water movement tendency across a semipermeable membrane.

Concentrated Urine

Urine with high solute concentration to conserve water.

Anterior Hypothalamus

Brain region involved in thermoregulation.

Chemical Bonds

Connections between atoms in proteins affected by heat.

Set Point

Desired level of body temperature or solute concentration.

Sweating

Cooling mechanism involving evaporation of sweat.

Shivering

Muscle contractions generating heat to raise body temperature.

Blood Volume

Amount of blood in the circulatory system.

Kidneys

Organs filtering blood and regulating water balance.

Body Water

70% of mammalian body composition.

Infection Response

Immune reaction involving fever and temperature regulation.

Temperature Receptors

Sensors detecting temperature changes in skin and organs.

Survival Advantage

Benefits of fever in fighting bacterial infections.

Concentration of Solutes

Measure of solute particles in body fluids.

Osmotic Thirst

Thirst triggered by osmotic pressure changes.

OVLT

Organum laminae terminalis; detects osmotic needs.

Subfornical Organ

Regulates thirst; has excitatory and inhibitory neurons.

Hypothalamus

Brain region controlling thirst and drinking behavior.

Vasopressin

Hormone regulating water retention from posterior pituitary.

Allostasis

Anticipation of physiological needs by the body.

Hypovolemic Thirst

Thirst due to low blood volume.

Angiotensinogen

Protein converted to angiotensin 1 and 2.

Renin

Enzyme released by kidneys in response to low blood pressure.

Angiotensin 2

Hormone that constricts blood vessels and triggers thirst.

Sodium-Specific Hunger

Preference for salty water when sodium is low.

Aldosterone

Hormone that retains sodium in response to low levels.

Taste Receptors

Altered by aldosterone and angiotensin 2 for salt intake.

Nucleus of the Tractus Solitarius

Brain area increasing salt intake.

Digestive System

Breaks down food into absorbable molecules.

Saliva

Contains enzymes that begin carbohydrate digestion.

Esophagus

Tube transporting food to the stomach.

Hydrochloric Acid

Substance in stomach aiding protein digestion.

Small Intestine

Site for digestion and absorption of nutrients.

Large Intestine

Absorbs water and minerals; prepares waste for excretion.

Lactase

Enzyme needed to digest lactose in milk.

Lactose Intolerance

Inability to digest lactose due to low lactase.

Lactose Metabolism

Ability to digest lactose in adulthood.

Tryptophan

Amino acid that aids melatonin production.

Carbohydrates and Tryptophan

Increase tryptophan availability by consuming carbs.

Insulin

Hormone that facilitates glucose entry into cells.

Phenylalanine

Amino acid that competes with tryptophan.

Sham Eating

Artificial eating without actual food intake.

Stomach Distention

Stretching of stomach walls signals satiety.

Vagus Nerve

Carries stomach stretch signals to the brain.

Duodenum

First part of small intestine, regulates satiety.

Oleoylethanolamide (OEA)

Hormone released by duodenum promoting satiety.

Cholecystokinin (CCK)

Hormone that inhibits appetite from the duodenum.

Glucagon

Hormone that stimulates glucose release from liver.

Leptin

Hormone monitoring body fat reserves.

Leptin Sensitivity

Sensitivity to leptin decreases with obesity.

Arcuate Nucleus

Brain region with hunger and satiety neurons.

Hunger Neurons

Neurons sensitive to hunger signals like ghrelin.

Satiety Neurons

Neurons sensitive to signals indicating fullness.

Paraventricular Nucleus (PVN)

Inhibits lateral hypothalamus, involved in satiety.

Melanocyte Hormones

Released from arcuate nucleus, regulate appetite.

Orexin

Neurotransmitter stimulating meal onset activity.

Lateral Hypothalamus

Controls feeding behavior and insulin secretion.

Ventromedial Hypothalamus (VMH)

Damage leads to overeating and weight gain.