Dictionary

Body systems

Anatomy and the conditions of each body system, from the heart and lungs to the skin.

facial nerveThe seventh cranial nerve, which moves the muscles of the face and carries taste from the front of the tongue.

FADH₂The reduced form of flavin adenine dinucleotide, a molecule that carries electrons inside cells during energy production.

failure to thrivePoor growth in a child, with weight gain well below what is expected for the child's age.

fallopian tubeOne of the two tubes that carry an egg from the ovary to the uterus, where fertilization usually happens.

fasciaA sheet or band of tough connective tissue that covers and separates muscles and organs.

fatty acidA building block of fats: a chain of carbon atoms that the body uses for energy and to build cells.

febrile seizureA seizure in a young child brought on by a fever, without an infection of the brain or another known cause.

fecalHaving to do with feces, the solid waste passed from the bowel; stool.

fecesSolid waste passed from the bowel through the anus, made of undigested food, water, bacteria and cells.

feedbackInformation about a result that is sent back to change what happens next, in the body or between people.

femoralRelating to the thigh or the femur, the thigh bone.

femoral arteryThe large artery that carries blood to the leg, running through the groin and down the thigh.

femurThe thigh bone, the long bone between the hip and the knee.

fertilityThe ability to become pregnant or to cause a pregnancy.

fertilizationThe joining of a sperm and an egg to form a single new cell, the start of a pregnancy.

fetalRelating to a fetus, the unborn baby from the ninth week of pregnancy until birth.

fetal heart rateThe number of times the unborn baby's heart beats per minute.

fetal heart rate variabilityThe small, irregular ups and downs of the baby's baseline heart rate seen on a fetal monitor tracing.

fetal stationHow far the presenting part of the fetus has moved down the birth canal, measured against the ischial spines of the pelvis.

fetusAn unborn baby from about the ninth week of development until birth.

fibrillationFast, uncoordinated twitching of muscle fibers, most often in the heart, so the muscle quivers instead of contracting together.

fibrinolysisThe body's process of breaking down a blood clot once it is no longer needed.

fibromyalgiaA long-term condition of widespread pain and tenderness in the muscles and soft tissues, with no damage to the joints.

fibrosisThe thickening and scarring of tissue, which replaces normal tissue with tough fibers.

fibrousMade of or containing tough threads (fibers), especially of connective tissue.

fibulaThe thin outer bone of the lower leg, beside the larger tibia.

fifth diseaseA common childhood viral illness caused by parvovirus B19, also called erythema infectiosum.

filtrationThe passing of fluid through a filter or membrane, which holds back larger particles; in the kidneys, the first step in making urine.

fingernailThe hard plate of keratin that covers the top of the end of each finger.

fingertipThe end of a finger.

FiO2Fraction of inspired oxygen: the percentage of oxygen in the air a person breathes in.

first trimesterThe first part of pregnancy, from the first day of the last menstrual period through the end of week 13.

fissureA narrow crack or split in the skin, a lining or an organ.

fistulaAn abnormal passage between two organs or vessels, or between an organ and the skin.

flatulenceGas in the stomach or intestines, or passing that gas through the anus.

flatusGas passed from the intestines through the anus.

flexionBending a joint so that the angle between the two body parts gets smaller.

fluidA liquid; in the body, the water and what is dissolved in it, inside and outside the cells.

fluid balanceThe match between the fluid that goes into the body and the fluid that leaves it.

fluid overloadToo much fluid in the body, in the blood vessels and the tissues.

fluid resuscitationGiving large amounts of IV fluid quickly to restore blood volume and blood flow to the organs.

fluid retentionExtra fluid that the body holds in its tissues instead of removing it.

fluid volumeThe amount of fluid in the body, or in one of its spaces such as the blood vessels.

folateA B vitamin (vitamin B9) the body needs to make DNA and new cells, including red blood cells.

follicleA small sac or cavity in the body, such as the pocket a hair grows from or the sac in the ovary that holds an egg.

folliculitisInflammation or infection of hair follicles, the small pockets in the skin that hairs grow from.

fontanelA soft spot on a baby's head where the skull bones have not yet joined.

foramen ovaleAn opening between the right and left upper chambers of the fetal heart that lets blood bypass the lungs before birth.

forearmThe part of the arm between the elbow and the wrist.

fossaA shallow hollow or dip in a bone or on the body's surface.