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Signalling molecules are chemical messengers (like hormones, neurotransmitters, growth factors) that transmit information between cells, enabling communication, coordination, and physiological responses in multicellular organisms, acting by binding to specific receptors on target cells to trigger internal changes, ranging from short-range local signals (paracrine) to long-distance travel (endocrine). They vary widely Read more

The hypothalamus is a small but crucial brain region linking the nervous and endocrine systems, acting as the body’s control center for maintaining homeostasis (internal balance) by regulating temperature, hunger, thirst, sleep, mood, stress, and hormone release via the pituitary gland. It receives signals from the body and brain, coordinating Read more

The sympathetic and parasympathetic nervous systems are the two branches of the autonomic nervous system, working in opposition to control involuntary functions like heart rate and digestion, with the sympathetic system driving “fight-or-flight” (action, stress response) by increasing energy use and preparing for threats, and the parasympathetic system promoting “rest-and-digest” Read more

The nervous system is the body’s command center, a complex network of nerves, the brain, and the spinal cord that coordinates actions, sensory information, and involuntary functions like breathing and heartbeats by transmitting electrical and chemical signals. It’s divided into the Central Nervous System (CNS), comprising the brain and spinal Read more

The endocrine system is a network of glands (like thyroid, pituitary, adrenals, pancreas) that produce and release hormones directly into the bloodstream to act as chemical messengers, controlling vital functions like metabolism, growth, mood, reproduction, and stress response by regulating distant organs and cells. It works with the nervous system Read more

Allostasis is the brain’s active process of maintaining stability (homeostasis) by making adaptive changes to physiological systems (like releasing cortisol/adrenaline) in anticipation of or in response to environmental challenges, essentially “stability through change”. While crucial for survival, chronic activation leads to allostatic load – wear and tear on the body Read more

Nerves are vital, cable-like bundles of fibers (axons) from nerve cells (neurons) that transmit electrochemical signals, acting as the body’s communication network between the brain, spinal cord, and the rest of the body, enabling sensation, movement, and controlling involuntary functions like breathing and digestion. They form the peripheral nervous system Read more

Homeostasis is the ability of living organisms to maintain a stable, relatively constant internal environment (like temperature, pH, water balance, blood sugar) despite changes in external conditions, ensuring cells and systems function optimally for survival. It’s a dynamic process involving feedback loops, primarily negative feedback, where the body detects deviations Read more

A metabolic response is any reaction by the body to a specific influence or impact. Metabolism is a general term describing the organic process in any cellular structure. A metabolic response can occur with respect to individual cells, a gland, an organ, or a process such as the cardiovascular system.

Gastric motility is the stomach’s coordinated muscle movement that processes food, mixing it and propelling it into the small intestine (duodenum) for digestion, involving relaxation to accept food, peristaltic waves to churn and break it down into chyme, and controlled emptying. This automatic process is controlled by the enteric nervous Read more