the movement of solutes against a gradient and requires the expenditure of energy (usually ATP).
anatomy the study of the structure and relationship between body parts.
antagonistic hormones hormones that act to return body conditions to within acceptable limits from opposite extremes.
antigen any molecule, usually a protein or polysaccharide, that can be identified as foreign or nonself. It may be a toxin, or a part of the protein coat of a virus, or a molecule unique to the plasma membranes.
appendicular skeleton the bones that make up the limbs, basically your arms, legs, hands, and feet.
arteries carry blood away from the heart.
atom the smallest quantity of an element that still possesses the characteristics of the element.
ATP (adenosine triphosphate) a common source of activation energy for metabolic reaction.
atria the two upper chambers of the heart.
autonomic nervous system (ANS) controls the activities of organs, glands, and various involuntary muscles.
axial skeleton the bones that revolve around the vertical axis of the skeleton, basically the spine and skull.
basal bodies at the base of each flagellum and cilium and appear to organize their development.
belly the part of the muscle between the origin and insertion.
Boyle's law describes the relationship between the pressure (P) and the volume (V) of a gas. The law states that if the volume increases, then the pressure must decrease (or vice versa).
capillaries microscopic blood vessels with extremely thin walls.
carbohydrate any of certain organic compounds, including the sugars, starches, and celluloses.
cardiac cycle describes all the activities of the heart through one complete heartbeat - that is, through one contraction and relaxation of both the atria and the ventricles.
cardiac muscle responsible for the rhythmic contractions of the heart.
cardiac output (CO) is the volume of blood pumped out of the right or left ventricle per minute. CO = SV X HR.
Nancy: Above, please use the multiplication symbol instead of X. Thanks!
cardiovascular system consists of the heart, blood vessels, and blood. This system transports nutrients, oxygen, and hormones to cells and removes metabolic waste. It protects the body and regulates body temperature.
catalyst accelerates the rate of a reaction.
cell the basic functional unit of all living things.
central nervous system (CNS) consists of the brain and the spinal cord.
centrioles a pair of centrioles located outside the nuclear envelope gives rise to the microtubules that make up the spindle apparatus used during cell division.
cerebrum consists of two cerebral hemispheres connected by a bundle of nerve fibers.
channel proteins provide passageways through the plasma membrane for certain water-soluble substances such as polar and charged molecules.
chromosomes made up of two identical halves called sister chromatids, which are joined at the centromere. Each consists of a single, tightly coiled molecule of DNA.
cilia structure that protrudes from the cell membrane and makes wavelike movements. Classified by length and number per cell, cilia are short and many. The numerous cilia that line the respiratory tract sweep away debris. Structurally cilia consists of microtubules arranged in a "9 + 2" array.
cofactors nonprotein molecules that assist enzymes.
compact bone the hard material that makes up the shaft of long bones and the outside surfaces of other bones.
compound when the atoms in a molecule are different. For example, H2O and C6H12O6, but not O2.
cones photoreceptor cells that respond to bright light and color and transmit sharp images.
coronary circulation the blood vessels that supply oxygen and nutrients to the tissues of the heart.
covalent bond a chemical bond that forms when electrons are shared between atoms.
cranial nerves nerves of the peripheral nervous system that originate from or terminate in the brain.
cytokinesis divides the cytoplasm in the cell.
cytology the study of cells at the microscopic level.
cytoplasm specialized bodies within a cell called organelles suspended in a fluid matrix, the cytosol.
cytoskeleton the internal structure of the cytoplasm.
cytosol a fluid matrix of water and dissolved substances such as proteins and nutrients.
Dalton's law states that the sum of the partial pressures of each gas in a mixture is equal to the total pressure of the mixture.
dermis the second layer of skin.
dialysis the diffusion of solutes across a selectively permeable membrane.
diastole a relaxation event of either the atria or ventricles.
diencephalon connects the cerebrum to the brain stem.
diffusion the net movement of substances from an area of higher concentration to an area of lower concentration.
digestive system broken into two parts is responsible for the digestion and absorption of nutrients.
disaccharide a carbohydrate consisting of two linked sugar molecules.
DNA (deoxyribonucleic acid) the part of a cell that stores genetic information.
dorsal refers to the back of the body.
effector corrects conditions according to the evaluation of the integrator.
electron transfer proteins involved in transferring electrons from one molecule to another during chemical reactions.
electrons the negative charge of an atom outside the nucleus.
elements make up matter and possess unique physical and chemical properties.
endocrine glands secrete hormones directly into the bloodstream.
endocrine system produces hormones that are instrumental in maintaining homeostasis and regulating reproduction and development.
endoplasmic reticulum (ER) stacks of flattened sacs involved in the production of various materials.
enzymes proteins that are specific for particular reactions.
epidermis the top layer of skin.
epithalamus contains the pineal gland.
epithelial membrane a combination of epithelial and connective tissues working together to perform a specific function.
epithelial tissue acts as a covering and lining on the outside surfaces of the body and lines the internal organs or secretes hormones or other products.
exocrine glands secrete their substances into tubes, or ducts, which carry the secretions to the epithelial surface. Examples include sweat, saliva, milk, and stomach acid.
female reproductive system consists of the ovaries, uterine tubes, uterus (womb), vagina (birth canal), and vulvae.
flagella structure that protrudes from the cell membrane and makes wavelike movements. Classified by length and number per cell, flagella are long and few. A single flagellum propels sperm. Structurally flagella consists of microtubules arranged in a "9 + 2" array.
formed element cells and cell fragments present in blood.
frontal (coronal) plane divides the body or organ vertically into a front and rear part.
gametes eggs and sperm.
ganglia clusters of cell bodies in the peripheral nervous system.
gastrointestinal (GI) tract is a continuous tube with two openings, the mouth and the anus. It includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine.
Golgi apparatus (Golgi complex or Golgi body) a group of flattened sacs arranged like a stack of bowls that function to modify and package proteins and lipids into vesicles.
gross (macroscopic) anatomy the study of body parts visible to the naked eye.
gustatory sense sense of taste.
heart rate (HR) the number of heartbeats per minute.
hematopoiesis production of red blood cells.
hemopoiesis the process that produces the formed elements of the blood and takes place in the red bone marrow of long bones.
hemostasis the stoppage of bleeding through vascular spasm, platelet plug, or coagulation.
Henry's law the greater the partial pressure of a gas, the greater the diffusion of the gas into the liquid.
histology the study of tissues at the microscopic level.
homeostasis the maintenance of stable, internal conditions within specific limits. A characteristic of all living systems.
horizontal (transverse) plane divides the body or organ horizontally into a top and bottom part.
hormone chemical messenger produced by a cell that effects specific changes in the cellular activity of other cells.
hydrogen bond a weak chemical bond that forms between the positively charged hydrogen atom and one covalently bonded molecule and the negatively charges area of another covalently bonded molecule.
hypodermis the layer between the dermis and the underlying tissues and organs.
immune system the third line of defense that consists of specific mechanisms and agents that target specific antigens.
induced-fit model describes how enzymes work.
inorganic compound compounds that do not contain carbon atoms. Water, O2, and NaCl are examples of inorganic compounds.
insertion the muscle end that attaches to the moving structure.
integrator a control center (often the brain).
integumentary system the skin and its accessory organs.
interatrial septum separates the left and right atria longitudinally in the heart.
interventricular septum separates the left and right ventricles longitudinally in the heart.
iris the colored portion of the eye that opens and closes to control the size of its circular opening, the pupil.
kidneys produce urine.
left atrium (and its auricle appendage) receive oxygenated blood from the lungs through four pulmonary veins and acts as a holding chamber for blood in readiness for its flow into the left ventricle.
left ventricle the pumping chamber of the heart for systemic circulation.
limbic system a network of neurons that extends over a wide range of areas of the brain. Imposes an emotional aspect to behaviors, experiences, and memories.
lipids a class of substances that are insoluble in water (and other polar solvents) but are soluble in nonpolar substances (like ether or chloroform).
living systems can be described from various perspectives, from the very broad (looking at the entire earth) to the very minute (individual atoms).
lymph nodes small, oval or bean-shaped bodies that occur along lymphatic vessels. They filter the lymph, destroy bacteria, toxins, and particulate matter, and they produce antibodies.
lymphatic system consists of lymphatic vessels, a fluid called lymph, lymph nodes, the thymus, and the spleen.
lymphocytes white blood cells (leukocytes) that provide an immune response that attacks specific kinds of nonself cells and foreign substances.
lysosomes vesicles from a Golgi apparatus that contain digestive enzymes that break down food, cellular debris, and foreign invaders such as bacteria.
macrophages enlarged monocytes (white blood cells) that engulf microbes and cellular debris.
major histocompatibility complex (MHC) (also called human leukocyte antigens, HLAs) is the mechanism by which the immune system is able to differentiate between self and nonself cells.
male reproductive system consists of the scrotum, testes, epidiymis, ductus deferens, ejaculatory ducts, urethra, spermatic cord, accessory sex glands, and the penis.
mammary glands sweat glands on a woman that are specialized for the production of milk.
matter anything that takes up space and has mass.
meiosis a reduction division, producing daughter cells that contain half the genetic information of the parent cell.
melatonin a hormone that helps regulate the biological clock (sleep-wake cycles).
metabolism the breakdown of substances, the formation of new products, or the transferring of energy from one substance to another.
microtubules protein fibers made of the protein tubulin and provide support and mobility for cellular activities found in the spindle apparatus.
mitochondria carry out aerobic respiration.
mitosis a process of cell division in which the nucleus is divided so that both daughter cells are genetically identical.
molecules atoms chemically bound together.
monosaccharide the simplest kind of carbohydrate consisting of a single sugar molecule.
motor neurons transmit impulses from the central nervous system to effectors (muscles or glands).
muscle tissues consist of skeletal muscle, cardiac muscle, and smooth muscle.
muscular system consists of skeletal muscles and their associated connective tissues. It does not include cardiac muscle or smooth muscle.
negative feedback a sensing mechanism detects a change in conditions beyond specific limits. A control center evaluates the change and activates the change and activates a second mechanism to correct the condition. The variant condition is canceled, or negated, so that conditions are returned to normal.
nephrons filtering units that number over a million in the kidneys.
nerve a bundle of nerve fibers in the peripheral nervous system held together with connective tissue.
nervous system consists of two parts: the central nervous system and the peripheral nervous system.
nervous tissue tissue that consists of two kinds of nerve cells, neurons and neuroglia.
neuroglia cells that support and protect neurons.
neuron a cell that transmits nerve impulses.
neurophysiology the study of how the nervous system functions.
neutrons the neutral charge in the nucleus of an atom.
nuclear division divides the genetic material in the nucleus.
nuclei clusters of cell bodies in the central nervous system.
nucleus the part of the cell that contains DNA, the hereditary information of the cell.
olfactory sense sense of smell.
oogenesis consists of the meiotic cell divisions that lead to the production of ova (eggs) in females.
organ a group of different kinds of tissues working together to perform a particular activity.
organelles bodies within the cytoplasm that serve to physically separate the various metabolic reactions that occur within cells.
organic compounds compounds that have carbon atoms.
organism a system possessing the characteristics of living things - the ability to obtain and process energy, the ability to respond to environmental changes, and the ability to reproduce.
osmosis the diffusion of water molecules across a selectively permeable membrane.
parasympathetic nervous system activates tranquil functions, such as stimulating the secretion of saliva or digestive enzymes into the stomach.
passive transport the movement of substances from regions of higher to lower concentration and do not require expenditure of energy.
peripheral nervous system (PNS) consists of nerves outside the central nervous system.
peristalsis the major means of propulsion in moving food along the digestive tract. Consists of a series of alternating contractions and relaxations of smooth muscle that lines the walls of the digestive organs and that forces food to move forward.
phagocytes white blood cells that wander throughout the body attacking bacteria and other foreign invaders.
physiology the study of the function of body parts and the body as a whole.
plasma (cell) membrane separates internal metabolic events from the external environment and controls the movement of materials into and out of the cell. It bounds the cell and encloses the nucleus and cytoplasm.
plasma straw-colored, liquid portion of the blood, which consists of water, proteins, waste products, nutrients, electrolytes, and respiratory gases.
platelets (thrombocytes) fragments of huge cells that adhere to damaged blood vessel walls and release enzymes that activate the stoppage of bleeding.
polysaccharide a carbohydrate that is a series of connected monosaccharides.
positive feedback an action intensifies a condition so that it is driven farther beyond normal limits.
primary sex organs (gonads) secrete hormones that produces gametes.
process of sight involves converting light energy into chemical energy.
proteins represent a class of molecules that have varied functions. Eggs, muscles, antibodies, silk, fingernails, and many hormones are partially or entirely proteins.
protons the positive charge in the nucleus of an atom.
pulmonary circulation deoxygenated blood travels from the right side of the heart to each of the two lungs. Within the lungs O2 enters and CO2 leaves so that oxygenated blood returns from the lungs to the left side of the heart.
pupil the circular opening of the eye. The size of the pupil is controlled by the iris. The size of the pupil regulates the amount of light entering the eye and helps bring objects into focus.
receptor a sensing mechanism.
receptor proteins provide binding sites for hormones or other trigger molecules.
red blood cells (erythrocytes or RBCs) transport oxygen and carbon dioxide in the blood.
remodeling the process of creating new bone and removing old bone.
reproduction the production of eggs and sperm and the processes leading to fertilization.
respiratory system delivers air to the lungs.
retina the inner nervous tunic of the eye that absorbs light in the pigmented epithelium and stores vitamin A by use of photoreceptor cells.
Rh blood group This is a complex group defined by the antigens produced by three different genes. The Rh factor determines positive or negative blood.
right atrium located in the upper right side of the heart, along with the right auricle, acts as a temporary storage chamber so that blood will be readily available for the right ventricle.
right ventricle the pumping chamber of the heart for pulmonary circulation.
RNA (ribonucleic acid) takes genetic instructions from DNA and directs various metabolic activities of the cell.
rods photoreceptors that are most sensitive to light and more numerous than cones. The provide vision in dim light and are more capable of detecting movement.
sagittal planes divide the body or organ vertically into a right and left part.
sensory neurons transmit impulses from skin and other sensory organ or from various places within the body to the central nervous system.
skeletal muscle attaches to bones and causes movements of the body; also known as striated muscle or voluntary muscle.
skeletal system bones, cartilage, and the membranes that line the bones.
smooth muscle lines the walls of hollow organs.
somatic nervous system (SNS) directs the contraction of skeletal muscles.
spermatogenesis the development of a spermatid into mature sperm cells.
spinal cord an extension of the brain stem that functions to transmit nerve impulses and spinal reflexes.
spleen the largest lymphatic organ and is located on the left side of the body between the diaphragm and stomach. It filters the blood, destroys old red blood cells, provides a reservoir of blood, is active in immune responses, and produces blood cells.
spongy bone consists of thin, irregularly shaped plates arranged in a latticelike network.
steroids are characterized by a backbone of four linked carbon rings. Examples of steroids include cholesterol and certain hormones, including testosterone and estrogen.
stroke volume (SV) the volume of blood ejected by each ventricle during a single contraction.
sympathetic nervous system involved in the stimulation of activities that prepare the body for action, such as increasing the heart rate.
synapse (synaptic cleft) a gap that separates the neuron from a muscle cell or another neuron.
systemic circulation oxygenated blood travels from the left side of the heart to the various areas of the body. Gas, nutrient, and waste exchange occurs across the capillary walls into the surrounding cells. The deoxygenated blood returns to the right side of the heart.
systole a contraction event of either the atria or ventricles.
tissue a group of similar cells performing a common function.
urinary system helps maintain homeostasis by regulating water balance and by removing harmful substances from the blood.
veins carry blood toward the heart.
ventricles the two lower chambers of the heart that serve as the pumping machines.
vesicles small, spherically shaped sacs that bud from the ends of a Golgi apparatus.
white blood cells (WBCs) protect the body from foreign microbes and toxins.
zygote the fusing of an egg and a sperm.