600 Introduction to Anatomy and Physiology
retina the innermost layer of the eye, containing
light-sensitive nerve endings that send impulses through
the optic nerves to the brain
retroperitoneal (REHT-roh-PER-i-toh-NEE-al) located
behind the peritoneum, the membrane that lines the
abdominopelvic cavity
Rh factor the antigen of the Rh blood group that is
found on the surface of red blood cells; people with the
Rh factor are Rh+ and those lacking it are Rh–
rheumatoid arthritis autoimmune disorder in which the
body’s own immune system attacks healthy joint tissues;
the most debilitating and painful form of arthritis
rhinitis (righ-NIGH-tis) infl ammation of the mucous
membranes that line the nasal passage
rhinoplasty reconstructive or cosmetic surgery of the
nose to correct its form or function
RhoGAM an immune serum that prevents a mother’s
blood from becoming sensitized to foreign antibodies
from her fetus
ribosomal RNA the major ingredient in ribosomes
(protein is the other ingredient); rRNA
ribosomes (RIGH-boh-sohmz) very large enzymes that
make polypeptides
right bronchomediastinal trunk (BRAHN-koh-MEE-dee-
as-tin-al) duct that drains lymph from the right side of
the chest and lower neck
right bundle branches the right leg or branch through
which electrical impulses are transmitted from the
bundle of His through the right ventricle
right jugular trunk duct that drains lymph from the right
side of the head
right lumbar trunk duct carrying lymph from the right
lower body toward the cisterna chyli
right subclavian trunk (sub-KLAY-vee-an) duct that
drains lymph from the right arm
RNA one of two kinds of information-carrying
nucleic acids found in cells; ribonucleic acid
RNA polymerase (pahl-IM-er-ays) the enzyme that
makes an RNA molecule complementary to a gene on
DNA
rods sensory cells in the retina that are activated in dim
light
root canal a hollow cavity in the tooth that provides a
passageway for nerves and blood vessels to reach the
pulp cavity from the jaw bone
rough endoplasmic reticulum membranous network in
the cytoplasm that is involved in protein synthesis
round window a membrane-covered opening beneath
the oval window of the middle ear
rule of nines a method used in calculating body surface
area affected by burns
S
saccharides (SAK-a-righd) sugar and starch molecules;
carbohydrates
sacroiliac joint (SA-kroh-IL-ee-ak) joint between the
sacrum and each ilium
sacrum (SAY-krum) fi ve fused vertebrae that form the
posterior of the pelvic girdle
saddle joint type of diarthrosis in which the articulating
bone surfaces are both shaped like the seat of a riding
saddle
sagittal plane (SAJ-i-tal) an invisible, vertical fl at surface
that divides the body into right and left halves
sagittal plane movements (SAJ-i-tal) forward and
backward motions of the body or body segments
saliva a clear, tasteless, odorless fl uid secreted from
glands in the oral cavity
salivary glands the saliva-secreting exocrine glands of
the oral cavity
saltatory conduction (SAWL-ta-TOH-ree) the rapid
skipping of an action potential from node to node on
myelinated neurons
salty one of the fi ve basic tastes
sarcolemma (SAR-koh-LEHM-a) the delicate membrane
surrounding each striated muscle fi ber
sarcomeres (SAR-koh-mairz) units composed of actin
and myosin that contract inside the muscle fi ber
satellite cells glial cells that provide cushioning and
support for a neuron
saturated fatty acids that have all single bonds
scales the fl aky, silver-white patches that appear in cases
of psoriasis
scapula (SKAP-yoo-la) shoulder blade
scapulothoracic joint (skap-yoo-loh-thoh-RAS-ik) joint
between each scapula and the underlying tissues of the
thorax; not a true joint
Schwann cells (shwahnn) units that form the
fatty myelin sheaths around nerve fi bers in the
parasympathetic nervous system
science a systematic process that creates new
knowledge and organizes it into a form of testable
explanations and predictions about an aspect of our
universe
scientifi c method a systematic process that can be used
to answer questions or fi nd solutions to problems
scientifi c research hypothesis an educated guess
about what the outcome of a study will be
scientifi c theory an explanation of some aspect of
the natural world that is based on rigorously tested,
repeatedly confi rmed research
sclera (SKLER-a) the tough, fi brous outer layer of the eye
scrotum a sac that encases the pair of oval testes
sebaceous glands (seh-BAY-shus) glands located all
over the body that produce sebum
sebum (SEE-bum) an oily substance that helps to keep
the skin and hair soft
secondary bronchi bronchi that arise from the
primary bronchi and lead to the tertiary bronchi
secondary follicle a maturing ovarian follicle that
contains the oocyte surrounded by layers of granulosa
cells
secondary immune response immune system response
to an infectious agent that it has encountered before
secondary oocyte a cell produced by division of a
primary oocyte in the fi rst stage of meiosis
secondary spinal curves those spinal curves that
develop after birth, including the cervical and lumbar
curves
second-degree burns burns that involve damage to both
the epidermis and the upper portion of the underlying
dermis; characterized by blisters
second-degree heart block a heart block in which the
impulse from the SA node is intermittently blocked
secretion the active movement of substances from the
blood into the fi ltrate, which will become urine
secretory phase the phase of the uterine cycle after
ovulation, during which the uterine glands secrete
mucus, under the infl uence of progesterone secreted by
the corpus luteum
self-antigen normal protein antigen on the surface of a
body cell; does not normally cause an immune reaction