Human Body & Physiology

Anatomy is the scientific study of biological structures, their organization, and their relationships, from microscopic components to whole organisms.

Blaschko's lines are normally invisible developmental patterns in the skin that become apparent in certain mosaic, inherited, and acquired skin disorders.

Bone is living mineralized connective tissue that supports vertebrate bodies, enables movement, and participates in mineral regulation.

Bone marrow is soft tissue within bones that produces blood cells and provides specialized environments for stem-cell maintenance and immune-cell development.

The brain is the central organ of the nervous system, integrating sensory information, coordinating bodily functions, and supporting thought, emotion, learning, and memory.

The central nervous system comprises the brain and spinal cord, integrating sensory information and coordinating movement, cognition, and essential bodily functions.

The paired cerebral hemispheres and their cortical and subcortical structures, supporting sensation, movement, memory, language, and cognition.

Digestion is the mechanical and chemical breakdown of food into substances that organisms can absorb and use.

The organs that break down food, absorb nutrients and remove waste in animals, including humans.

Dopamine is a catecholamine neurotransmitter and hormone that shapes movement, reward learning, motivation, cognition, and several physiological functions in the body.

The duodenum is the first part of the small intestine, where stomach contents mix with digestive secretions and undergo further digestion and nutrient absorption.

Epinephrine (adrenaline) is a catecholamine hormone and neurotransmitter that drives the body's fight-or-flight response and is a core emergency drug.

Homeostasis is the active regulation of internal conditions within ranges compatible with the functioning of a living system.

A hormone is a biological chemical messenger that coordinates cellular activity, growth, metabolism, reproduction, and responses to changing conditions.

The immune system is a coordinated network of cells, tissues, organs, and molecules that protects against infection while regulating responses to the body’s own tissues.

Inflammation is a coordinated response to infection or tissue injury that supports defense and repair but can cause damage when excessive or persistent.

The kidney is a paired organ that filters blood, removes metabolic waste, produces urine, regulates fluid, electrolyte, and acid–base balance, and secretes hormones affecting blood pressure and red blood cell production.

A lymph node is a small, encapsulated organ of the lymphatic system that filters lymph and hosts immune cells that start adaptive immune responses.

The lymphatic system returns tissue fluid to the bloodstream, transports absorbed fats, and supports immune responses through a network of vessels and lymphoid organs.

Menopause is the permanent end of menstruation, confirmed after twelve months without a period, usually around age 51, and driven by declining ovarian hormone output.

The nervous system is the body's network of neurons and glia that senses, processes, and coordinates responses, from reflexes to thought and memory.

An organ is a structural unit of two or more tissues that work together to perform a shared function in a multicellular organism.

The pancreas is an abdominal gland that secretes digestive enzymes into the intestine and hormones into the blood to regulate glucose and nutrient metabolism.

Physiology is the study of how living organisms function, from molecular and cellular mechanisms to coordinated whole-organism processes.

Pregnancy is the period from conception to birth in which an embryo and fetus develop inside the mother's body, typically lasting about 40 weeks in humans.

Serotonin is a monoamine signaling molecule that works as a neurotransmitter in the brain and as a hormone-like regulator in the gut, blood, and other tissues.

The spinal cord is the part of the central nervous system inside the spinal canal. It carries signals between the brain and the body and performs local reflex processing.

The spleen is a blood-filtering lymphoid organ involved in immune defense, blood-cell maintenance, and iron recycling.

The stomach is a muscular digestive organ between the esophagus and small intestine that stores food and begins protein digestion with acid and enzymes.

The thymus is a primary lymphoid organ where T cells mature and undergo selection that supports immune defense and tolerance to the body’s own tissues.