Other forms: membranes

A membrane is a thin layer of something. For an example of a membrane, you don’t have to look far: your skin is a kind of membrane.

Membranes are thin and flexible, but usually still strong enough to protect what’s inside or underneath them. Biologists often study membranes, such as those that surround your cells and organs. There are also membranes that don’t have anything to do with biology. A high-tech jacket might have a waterproof membrane to keep you dry in the rain.

Definitions of membrane
  1. noun
    a pliable sheet of tissue that covers or lines or connects the organs or cells of animals or plants
    synonyms: tissue layer
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    the membrane that forms the wall of the blastocyst in early development; aids implantation in the uterine wall
    chorioallantoic membrane, chorioallantois
    the very vascular fetal membrane composed of the fused chorion and adjacent wall of the allantois
    membrane connecting the toes of some aquatic birds and mammals
    Bowman's capsule, capsula glomeruli, glomerular capsule
    thin double membrane surrounding the glomerulus of a nephron
    outer membrane covering an axon
    basilar membrane
    a membrane in the cochlea that supports the organ of Corti
    fetal membrane
    any membrane that functions for the protection or nourishment or respiration or excretion of a developing fetus
    choroid, choroid coat
    a highly vascular membrane in the eye between the retina and the sclera; a dark pigmentation minimizes the scattering of light inside the eye
    ciliary body
    the part of the tunic of the eye between the choroid coat and the iris
    the transparent dome-shaped anterior portion of the outer covering of the eye; it covers the iris and pupil and is continuous with the sclera
    diaphragm, midriff
    (anatomy) a muscular partition separating the abdominal and thoracic cavities; functions in respiration
    eardrum, myringa, tympanic membrane, tympanum
    the membrane in the ear that vibrates to sound
    membrane lining the inside of the skull
    vascular membrane that lines the inner surface of long bones
    thin epithelial membrane lining the ventricles of the brain and the spinal cord canal
    fertilization membrane
    the membrane that forms around a fertilized ovum and prevents penetration by additional spermatozoon
    hyaloid, hyaloid membrane
    the transparent membrane enveloping the vitreous humor of the eye and separating it from the retina
    the innermost membrane of an organ (especially the inner lining of an artery or vein or lymphatic vessel)
    muscular diaphragm that controls the size of the pupil which in turn controls the amount of light that enters the eye; it forms the colored portion of the eye
    a thin membrane that is one of the calcified layers that form bones
    meninges, meninx
    a membrane (one of 3) that envelops the brain and spinal cord
    mucosa, mucous membrane
    mucus-secreting membrane lining all body cavities or passages that communicate with the exterior
    a dense fibrous membrane covering the surface of bones (except at their extremities) and serving as an attachment for tendons and muscles; contains nerves and blood vessels that nourish the enclosed bone
    tissue layer around small blood vessels
    the innermost light-sensitive membrane covering the back wall of the eyeball; it is continuous with the optic nerve
    an extensible membrane enclosing the contractile substance of a muscle fiber
    semipermeable membrane
    a membrane (as a cell membrane) that allows some molecules to pass through but not others
    serosa, serous membrane
    a thin membrane lining the closed cavities of the body; has two layers with a space between that is filled with serous fluid
    synovial membrane, synovium
    a thin membrane in synovial (freely moving) joints that lines the joint capsule and secretes synovial fluid
    adventitia, tunic, tunica
    an enveloping or covering membrane or layer of body tissue
    the vascular fetal membrane that lies below the chorion and develops from the hindgut in many embryonic higher vertebrates (reptiles, birds and mammals)
    caul, embryonic membrane, veil
    the inner membrane of embryos in higher vertebrates (especially when covering the head at birth)
    cell membrane, cytomembrane, plasma membrane
    a thin membrane (a double layer of lipids) enclosing the cytoplasm of a cell; proteins in the membrane control passage of ions (like sodium or potassium or calcium) in and out of the cell
    a transparent lubricating mucous membrane that covers the eyeball and the under surface of the eyelid
    arcus, arcus senilis
    a whitish deposit in the shape of an arc that is sometimes seen in the cornea
    perforated eardrum
    an eardrum with a hole or tear in it; can interfere with normal hearing and cause other ear problems
    the thin serous membrane around the lungs and inner walls of the chest
    a transparent membrane that lines the abdominal cavity in mammals and covers most of the viscera
    the membrane that lines the cavities of the heart and forms part of the heart valves
    a serous membrane with two layers that surrounds the heart
    epicardium, visceral pericardium
    the innermost of the two layers of the pericardium
    parietal pericardium
    the tough outermost layer of the pericardium that is attached to the diaphragm and the sternum
    the two innermost layers of the meninges; cerebrospinal fluid circulates between these innermost layers
    dura, dura mater
    the outermost (and toughest) of the 3 meninges
    arachnoid, arachnoid membrane
    the middle of the 3 meninges
    pia mater
    the highly vascular innermost of the 3 meninges
    (pregnancy) the mucous membrane that lines the uterus; thickens under hormonal control and (if pregnancy does not occur) is shed in menstruation; if pregnancy occurs it is shed along with the placenta at parturition
    umbilical, umbilical cord
    membranous duct connecting the fetus with the placenta
    hymen, maidenhead, virginal membrane
    a fold of tissue that partly covers the entrance to the vagina of a virgin
    whitish tunic
    type of:
    animal tissue
    the tissue in the bodies of animals
  2. noun
    a thin pliable sheet of material
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    drumhead, head
    a membrane that is stretched taut over a drum
    gel, gelatin
    a thin translucent membrane used over stage lights for color effects
    type of:
    flat solid, sheet
    a flat artifact that is thin relative to its length and width
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