homeostasis

Homeostasis

The ability of the body to maintain a stable internal environment despite changes in external conditions.

Feedback Systems

Mechanisms by which the body monitors and responds to changes in its internal environment to maintain homeostasis.

Positive Feedback

A feedback mechanism that amplifies or increases the original change until a goal is reached, such as in childbirth or blood clotting.

Negative Feedback

A feedback mechanism that reverses a change to bring systems back to normal, such as regulating body temperature or blood sugar.

Thermoregulation

The process by which the body maintains a stable internal temperature.

Hypothalamus

The part of the brain that controls temperature regulation and other homeostatic functions.

CNS

Central Nervous System; includes the brain and spinal cord which act as the control center.

PNS

Peripheral Nervous System; all nerves outside the brain and spinal cord that carry messages to and from the CNS.

Somatic Nervous System

Part of the PNS responsible for voluntary movements, controlling skeletal muscles.

Autonomic Nervous System

Part of the PNS that controls involuntary functions such as heart rate and digestion.

Sympathetic Nervous System

The part of the autonomic nervous system that triggers the fight or flight response.

Parasympathetic Nervous System

The part of the autonomic nervous system that promotes rest and digest activities.

Reflex Arc

An automatic response that does not involve the brain, relying solely on the spinal cord.

Hormones

Chemical regulators produced by glands that affect cells in other parts of the body.

Steroid Hormones

Hormones that are fat soluble and can pass through cell membranes, derived from cholesterol.

Protein Hormones

Water-soluble hormones that interact with cells using a second messenger system, such as cAMP.

Pituitary Gland

Often referred to as the master gland; it regulates other glands and hormone release.

Insulin

A hormone produced by the pancreas that lowers blood sugar levels.

Glucagon

A hormone produced by the pancreas that raises blood sugar levels by releasing sugar from the liver.

Thyroid Gland

Gland responsible for metabolism regulation by producing hormones like thyroxine.

Parathyroid Hormone (PTH)

Hormone that increases blood calcium levels by releasing it from bones.

Adrenal Cortex

Part of the adrenal glands that produces cortisol (stress hormone) and aldosterone.

Neurons

Electrically excitable cells that transmit nerve impulses.

Action Potential

A temporary change in electrical charge that occurs in a neuron when it is activated.

Agonist

A substance that mimics neurotransmitters and enhances their effect.

Antagonist

A substance that blocks neurotransmitters and reduces their effect.

Excretory System

System that produces urine and contributes to homeostasis by excreting waste and maintaining balance.

Renal Vein

The blood vessel that carries clean blood away from the kidney.

Urinary System

System responsible for the production and elimination of urine.

Filtration

The process in which solutes and water move from dirty blood into the glomerulus.

Reabsorption

The process by which substances are reabsorbed from the nephron back into the blood.

Secretion

Movement of waste from the blood into the nephron, occurring at the distal tubule.

Excretion

The removal of remaining wastes from the kidney to the bladder as urine.