(45) D3.3 Homeostasis [IB Biology SL/HL]

Homeostasis

The maintenance of stable internal conditions regardless of fluctuations in the external environment.

Negative feedback loop

A process that promotes stability by returning values back to the original range when a variable goes beyond the acceptable limit.

Positive feedback loop

A process that increases the distance between the current range and the original level, driving change.

Glucagon

A hormone secreted by the alpha cells of the pancreas that stimulates the conversion of glycogen into glucose.

Insulin

A hormone secreted by the beta cells of the pancreas that facilitates glucose uptake and lowers blood glucose levels.

Thermoregulation

The process of maintaining a stable internal body temperature through physiological and behavioral changes.

Endocrine glands

Glands that secrete hormones directly into the bloodstream.

Exocrine glands

Glands that secrete substances through a duct to an outside surface.

Thyroxine

A hormone released by the thyroid gland that increases cellular metabolism.

Vasoconstriction

The physiological response of blood vessels tightening, reducing blood flow to the skin and keeping warmth in the core.

Vasodilation

The physiological response of blood vessels widening, increasing blood flow to the skin to help cool the body.

Adipose tissue

Body tissue that stores fat and is involved in thermoregulation and energy metabolism.

Type 1 diabetes

A condition characterized by little or no insulin production due to autoimmune destruction of beta cells.

Type 2 diabetes

A condition characterized by decreased sensitivity to insulin, leading to high blood glucose levels despite normal insulin production.

Homeostatic range

The narrow range of values that physiological parameters must stay within for optimal function.

Hypothalamus

A brain structure that monitors and interprets information from thermoreceptors to initiate thermoregulation responses.

Brown adipose tissue

A type of fat tissue involved in heat production through uncoupled respiration.

Thermoreceptors

Sensory receptors that monitor temperature changes in the body and environment.

Feedback loops

Processes that regulate physiological functions, including negative and positive feedback.

Glycogen

A polysaccharide made up of glucose molecules that serves as an energy storage form in animals.

Skeletal muscle tissue

Muscle tissue that is under voluntary control and is responsible for body movements.

Cardiac muscle tissue

Involuntary muscle tissue found only in the heart, responsible for pumping blood.

Smooth muscle tissue

Involuntary muscle tissue found in walls of hollow organs, regulating automatic movements.

Hormones in thermoregulation

Hormones such as adrenaline and thyroid hormones that help regulate body temperature.

Insulin action mechanism

Insulin promotes glucose uptake in cells and stimulates glycogen synthesis in the liver.

Glucagon action mechanism

Glucagon stimulates glycogen breakdown in the liver, releasing glucose into the bloodstream.

Insulin resistance

A condition where body cells do not respond effectively to insulin, often seen in Type 2 diabetes.

Managing Type 1 diabetes

Typically managed with insulin therapy, monitoring blood glucose levels, and carbohydrate counting.

Managing Type 2 diabetes

Often involves lifestyle changes, dietary modifications, exercise, and may require medication or insulin.

Physiological acclimatization

Adaptations the body undergoes to cope with prolonged exposure to extreme temperatures.

Shivering thermogenesis

Involuntary muscle contractions that generate heat to maintain body temperature in cold environments.

Heat exhaustion

A heat-related illness characterized by heavy sweating and a rapid pulse due to excessive heat exposure.

Heat stroke

A severe heat-related illness requiring immediate medical attention, characterized by a body temperature over 104°F.

Role of brown adipose tissue in thermoregulation

Brown adipose tissue helps generate heat by burning calories through uncoupled respiration.

White adipose tissue

Storage fat that helps insulate the body and store energy, but has a limited role in thermoregulation.

Thermal conductivity of skin

The ability of skin to transfer heat, influencing heat loss or retention in the body.