Homeostasis and Negative Feedback Mechanisms

This set of vocabulary flashcards covers the fundamental concepts of homeostasis, including the regulation of glucose, carbon dioxide, water, salt levels, and body temperature as described in the lecture notes.

Homeostasis

The process of maintaining a constant, internal environment within narrow limits, despite changes that take place internally and externally.

Tissue fluid

The internal environment of the body that surrounds cells, supplying essential substances, removing waste, and maintaining correct pH and optimal temperature.

Negative feedback mechanism

A process of correction where a change from the norm is detected and corrected, usually in the opposite direction.

Receptor

Sensory neurons and organs that detect changes in the internal environment.

Control centre

The brain and nervous system that processes information from receptors and activates an effector.

Effector

Endocrine glands, hormones, or body organs that respond to instructions from the control centre to correct an imbalance.

Hyperglycaemia

A condition where the glucose level is above $180\,mg$ per $100\,ml$ of blood.

Hypoglycaemia

A condition where the glucose level is below $70\,mg$ per $100\,ml$ of blood.

Insulin

A hormone secreted by the pancreas that travels to the liver to stimulate the conversion of excess glucose to glycogen for storage.

Glucagon

A hormone secreted by the pancreas that travels to the liver to stimulate the conversion of stored glycogen to glucose.

Diabetes mellitus

A disorder caused by an imbalance in blood glucose levels.

Goitre

A disorder caused by an imbalance in thyroxin levels.

Medulla oblongata

The control centre in the brain that detects changes in recordable $CO_2$ levels and adjusts breathing and heart rates.

Chemoreceptors

Receptor cells located in the carotid artery in the neck and the medulla oblongata that detect changes in blood $pH$ or high $CO_2$ levels.

Osmoregulation

The maintenance of water and salt balance in the body to ensure proper cell functioning and metabolic processes.

ADH (Anti-diuretic hormone)

A hormone released by the pituitary gland when water levels are low, causing the collecting ducts of the nephron to become more permeable to water.

Osmoreceptors

Receptors in the hypothalamus that detect excessive water loss or changes in blood water levels.

Aldosterone

A hormone released by the adrenal cortex that regulates salt balance by increasing sodium ion reabsorption in the kidneys.

Osmolarity

The osmotic pressure determined by the concentration of salts (sodium and potassium ions), which dictates ion movement into and out of cells.

Thermoregulation

The maintenance of a constant internal body temperature, typically $37\,^{\circ}C$, by balancing heat production and heat loss.

Endothermic

Animals, such as mammals and birds, that regulate their own body temperature via respiration to keep it constant.

Ectothermic

Animals, such as reptiles and fish, that obtain heat from the environment, resulting in varying body temperatures.

Radiation

The loss of heat energy from a warm body to a colder environment.

Conduction

The loss of heat energy from hot to cold objects through physical contact.

Convection

A process where heat moves from a hot object, rises, and is replaced by cold air.

Evaporation

The loss of heat by using body heat to change sweat into water vapour, also known as evaporative cooling.

Vasodilation

The process where circular muscles of dermal arterioles relax and capillaries dilate, allowing more blood to flow near the skin surface to lose heat.

Vasoconstriction

The constriction of circular muscles in the dermal arterioles, limiting blood flow to the skin surface to reduce heat loss.

Hypothermia

A condition occurring when the body temperature remains below $37\,^{\circ}C$ for a long period, causing the body to lose more heat than it can produce.

Hyperthermia

A condition occurring when the body temperature increases above $37\,^{\circ}C$ for a long period because the body absorbs more heat than it can lose.

Sebaceous glands

Skin glands that produce sebum, an oily/waxy secretion that prevents dehydration.