text
stringlengths
2
2.33k
source
stringclasses
826 values
urethra : the tube that conducts urine from the urinary bladder to the external environment
https://openstax.org/books/concepts-biology/pages/16-key-terms
urinary bladder : the structure that the ureters empty the urine into
https://openstax.org/books/concepts-biology/pages/16-key-terms
vein : a blood vessel that brings blood back to the heart
https://openstax.org/books/concepts-biology/pages/16-key-terms
ventricle : (of the heart) a large chamber of the heart that pumps blood into arteries
https://openstax.org/books/concepts-biology/pages/16-key-terms
vertebral column : (also, spine) the column that surrounds and protects the spinal cord, supports the head, and acts as an attachment point for ribs and muscles of the back and neck
https://openstax.org/books/concepts-biology/pages/16-key-terms
vitamin : an organic substance necessary in small amounts to sustain life
https://openstax.org/books/concepts-biology/pages/16-key-terms
Viruses are acellular entities that can usually only be seen with an electron microscope. Their genomes contain either DNA or RNA, and they replicate using the replication proteins of a host cell. Viruses are diverse, infecting archaea, bacteria, fungi, plants, and animals. Viruses consist of a nucleic-acid core surrou...
https://openstax.org/books/concepts-biology/pages/17-chapter-summary
Viral replication within a living cell always produces changes in the cell, sometimes resulting in cell death and sometimes slowly killing the infected cells. There are six basic stages in the virus replication cycle: attachment, penetration, uncoating, replication, assembly, and release. A viral infection may be produ...
https://openstax.org/books/concepts-biology/pages/17-chapter-summary
Viruses cause a variety of diseases in humans. Many of these diseases can be prevented by the use of viral vaccines, which stimulate protective immunity against the virus without causing major disease. Viral vaccines may also be used in active viral infections, boosting the ability of the immune system to control or de...
https://openstax.org/books/concepts-biology/pages/17-chapter-summary
The innate immune system consists first of physical and chemical barriers to infection including the skin and mucous membranes and their secretions, ciliated surfaces, and body hairs. The second line of defense is an internal defense system designed to counter pathogenic threats that bypass the physical and chemical ba...
https://openstax.org/books/concepts-biology/pages/17-chapter-summary
The adaptive immune response is a slower-acting, longer-lasting, and more specific response than the innate response. However, the adaptive response requires information from the innate immune system to function. APCs display antigens on MHC molecules to naïve T cells. T cells with cell-surface receptors that bind a s...
https://openstax.org/books/concepts-biology/pages/17-chapter-summary
Immune disruptions may involve insufficient immune responses or inappropriate immune responses. Immunodeficiency increases an individual's susceptibility to infections and cancers. Hypersensitivities are misdirected responses either to harmless foreign particles, as in the case of allergies, or to the individual’s ow...
https://openstax.org/books/concepts-biology/pages/17-chapter-summary
acellular : lacking cells
https://openstax.org/books/concepts-biology/pages/17-key-terms
active immunity : an immunity that occurs as a result of the activity of the body’s own cells rather than from antibodies acquired from an external source
https://openstax.org/books/concepts-biology/pages/17-key-terms
adaptive immunity : a specific immune response that occurs after exposure to an antigen either from a pathogen or a vaccination
https://openstax.org/books/concepts-biology/pages/17-key-terms
allergy : an immune reaction that results from immediate hypersensitivities in which an antibody-mediated immune response occurs within minutes of exposure to a harmless antigen
https://openstax.org/books/concepts-biology/pages/17-key-terms
antibody : a protein that is produced by plasma cells after stimulation by an antigen; also known as an immunoglobulin
https://openstax.org/books/concepts-biology/pages/17-key-terms
antigen : a macromolecule that reacts with cells of the immune system and which may or may not have a stimulatory effect
https://openstax.org/books/concepts-biology/pages/17-key-terms
antigen-presenting cell (APC) : an immune cell that detects, engulfs, and informs the adaptive immune response about an infection by presenting the processed antigen on its cell surface
https://openstax.org/books/concepts-biology/pages/17-key-terms
apoptosis : the cell death caused by induction of a cell’s own internal mechanisms either as a natural step in the development of a multicellular organism or by other environmental factors such as signals from cells of the immune system
https://openstax.org/books/concepts-biology/pages/17-key-terms
attenuation : the weakening of a virus during vaccine development
https://openstax.org/books/concepts-biology/pages/17-key-terms
autoantibody : an antibody that incorrectly marks “self” components as foreign and stimulates the immune response
https://openstax.org/books/concepts-biology/pages/17-key-terms
autoimmunity : a type of hypersensitivity to self-antigens
https://openstax.org/books/concepts-biology/pages/17-key-terms
B cell : a lymphocyte that matures in the bone marrow
https://openstax.org/books/concepts-biology/pages/17-key-terms
capsid : the protein coating of the viral core
https://openstax.org/books/concepts-biology/pages/17-key-terms
cell-mediated immune response : an adaptive immune response that is controlled by T cells
https://openstax.org/books/concepts-biology/pages/17-key-terms
complement system : an array of approximately 20 soluble proteins of the innate immune system that enhance phagocytosis, bore holes in pathogens, and recruit lymphocytes
https://openstax.org/books/concepts-biology/pages/17-key-terms
cytokine : a chemical messenger that regulates cell differentiation, proliferation, and gene expression to effect immune responses
https://openstax.org/books/concepts-biology/pages/17-key-terms
cytopathic : causing cell damage
https://openstax.org/books/concepts-biology/pages/17-key-terms
cytotoxic T lymphocyte (TC) : an adaptive immune cell that directly kills infected cells via enzymes, and that releases cytokines to enhance the immune response
https://openstax.org/books/concepts-biology/pages/17-key-terms
dendritic cell : an immune cell that processes antigen material and presents it on the surface of its cell in MHC class II molecules and induces an immune response in other cells
https://openstax.org/books/concepts-biology/pages/17-key-terms
effector cell : a lymphocyte that has differentiated, such as a B cell, plasma cell, or cytotoxic T cell
https://openstax.org/books/concepts-biology/pages/17-key-terms
glycoprotein : a protein molecule with attached carbohydrate molecules
https://openstax.org/books/concepts-biology/pages/17-key-terms
helper T lymphocyte (TH) : a cell of the adaptive immune system that binds APCs via MHC class II molecules and stimulates B cells or secretes cytokines to initiate the immune response
https://openstax.org/books/concepts-biology/pages/17-key-terms
humoral immune response : the adaptive immune response that is controlled by activated B cells and antibodies
https://openstax.org/books/concepts-biology/pages/17-key-terms
hypersensitivity : a spectrum of inappropriate immune responses toward harmless foreign particles or self-antigens; occurs after tissue sensitization and includes immediate-type (allergy), delayed-type, and autoimmunity
https://openstax.org/books/concepts-biology/pages/17-key-terms
immune tolerance : an acquired ability to prevent an unnecessary or harmful immune response to a detected foreign body known not to cause disease
https://openstax.org/books/concepts-biology/pages/17-key-terms
immunodeficiency : a failure, insufficiency, or delay at any level of the immune system, which may be acquired or inherited
https://openstax.org/books/concepts-biology/pages/17-key-terms
inflammation : the localized redness, swelling, heat, and pain that results from the movement of leukocytes through opened capillaries to a site of infection
https://openstax.org/books/concepts-biology/pages/17-key-terms
innate immunity : an immunity that occurs naturally because of genetic factors or physiology, and is not caused by infection or vaccination
https://openstax.org/books/concepts-biology/pages/17-key-terms
interferon : a cytokine that inhibits viral replication
https://openstax.org/books/concepts-biology/pages/17-key-terms
lymph : the watery fluid present in the lymphatic circulatory system that bathes tissues and organs with protective white blood cells and does not contain erythrocytes
https://openstax.org/books/concepts-biology/pages/17-key-terms
lymphocyte : a type of white blood cell that includes natural killer cells of the innate immune system and B and T cells of the adaptive immune system
https://openstax.org/books/concepts-biology/pages/17-key-terms
macrophage : a large phagocytic cell that engulfs foreign particles and pathogens
https://openstax.org/books/concepts-biology/pages/17-key-terms
major histocompatibility complex (MHC) I : a group of proteins found on the surface of all nucleated cells that signals to immune cells whether the cell is normal or is infected or cancerous; it also provides the appropriate sites into which antigens can be loaded for recognition by lymphocytes
https://openstax.org/books/concepts-biology/pages/17-key-terms
major histocompatibility complex (MHC) II molecule : a protein found on the surface of antigen-presenting cells that signals to immune cells whether the cell is normal or is infected or cancerous; it provides the appropriate template into which antigens can be loaded for recognition by lymphocytes
https://openstax.org/books/concepts-biology/pages/17-key-terms
mast cell : a leukocyte that produces inflammatory molecules, such as histamine, in response to large pathogens
https://openstax.org/books/concepts-biology/pages/17-key-terms
memory cell : an antigen-specific B or T lymphocyte that does not differentiate into an effector cell during the primary immune response but that can immediately become an effector cell on reexposure to the same pathogen
https://openstax.org/books/concepts-biology/pages/17-key-terms
monocyte : a type of white blood cell that circulates in the blood and lymph and differentiates into a macrophage after it moves into infected tissue
https://openstax.org/books/concepts-biology/pages/17-key-terms
natural killer (NK) cell : a lymphocyte that can kill cells infected with viruses or tumor cells
https://openstax.org/books/concepts-biology/pages/17-key-terms
neutrophil : a phagocytic leukocyte that engulfs and digests pathogens
https://openstax.org/books/concepts-biology/pages/17-key-terms
passive immunity : an immunity that does not result from the activity of the body’s own immune cells but by transfer of antibodies from one individual to another
https://openstax.org/books/concepts-biology/pages/17-key-terms
primary immune response : the response of the adaptive immune system to the first exposure to an antigen
https://openstax.org/books/concepts-biology/pages/17-key-terms
secondary immune response : the response of the adaptive immune system to a second or later exposure to an antigen mediated by memory cells
https://openstax.org/books/concepts-biology/pages/17-key-terms
T cell : a lymphocyte that matures in the thymus gland
https://openstax.org/books/concepts-biology/pages/17-key-terms
vaccine : a weakened solution of virus components, viruses, or other agents that produce an immune response
https://openstax.org/books/concepts-biology/pages/17-key-terms
viral envelope : a lipid bilayer that envelops some viruses
https://openstax.org/books/concepts-biology/pages/17-key-terms
virion : an individual virus particle outside a host cell
https://openstax.org/books/concepts-biology/pages/17-key-terms
white blood cell : a nucleated cell found in the blood that is a part of the immune system; also called leukocytes
https://openstax.org/books/concepts-biology/pages/17-key-terms
Reproduction may be asexual when one individual produces genetically identical offspring, or sexual when the genetic material from two individuals is combined to produce genetically diverse offspring. Asexual reproduction in animals occurs through fission, budding, fragmentation, and parthenogenesis. Sexual reproductio...
https://openstax.org/books/concepts-biology/pages/18-chapter-summary
Sexual reproduction starts with the combination of a sperm and an egg in a process called fertilization. This can occur either outside the bodies or inside the female. The method of fertilization varies among animals. Some species release the egg and sperm into the environment, some species retain the egg and receive t...
https://openstax.org/books/concepts-biology/pages/18-chapter-summary
The early stages of embryonic development begin with fertilization. The process of fertilization is tightly controlled to ensure that only one sperm fuses with one egg. After fertilization, the zygote undergoes cleavage to form the blastula. The blastula, which in some species is a hollow ball of cells, undergoes a pro...
https://openstax.org/books/concepts-biology/pages/18-chapter-summary
The reproductive structures that evolved in land animals allow them to mate, fertilize internally, and support the growth and development of offspring. Gametogenesis, the production of sperm (spermatogenesis) and eggs (oogenesis), takes place through the process of meiosis.
https://openstax.org/books/concepts-biology/pages/18-chapter-summary
The reproductive cycles are controlled by hormones released from the hypothalamus and anterior pituitary and hormones from reproductive tissues and organs. The hypothalamus monitors the need for FSH and LH production and release from the anterior pituitary. FSH and LH affect reproductive structures to cause the formati...
https://openstax.org/books/concepts-biology/pages/18-chapter-summary
Human pregnancy begins with fertilization of an egg and proceeds through the three trimesters of gestation. The first trimester lays down the basic structures of the body, including the limb buds, heart, eyes, and the liver. The second trimester continues the development of all of the organs and systems. The third trim...
https://openstax.org/books/concepts-biology/pages/18-chapter-summary
asexual reproduction : a mechanism that produces offspring that are genetically identical to the parent
https://openstax.org/books/concepts-biology/pages/18-key-terms
blastocyst : the structure formed when cells in the mammalian blastula separate into an inner and outer layer
https://openstax.org/books/concepts-biology/pages/18-key-terms
budding : a form of asexual reproduction that results from the outgrowth of a part of an organism leading to a separation from the original animal into two individuals
https://openstax.org/books/concepts-biology/pages/18-key-terms
bulbourethral gland : the paired glands in the human male that produce a secretion that cleanses the urethra prior to ejaculation
https://openstax.org/books/concepts-biology/pages/18-key-terms
clitoris : a sensory and erectile structure in female mammals, homologous to the male penis, stimulated during sexual arousal
https://openstax.org/books/concepts-biology/pages/18-key-terms
corpus luteum : the endocrine tissue that develops from an ovarian follicle after ovulation; secretes progesterone and estrogen during pregnancy
https://openstax.org/books/concepts-biology/pages/18-key-terms
estrogen : a reproductive hormone, usually present in animals of any sex, which in females assists in endometrial regrowth, ovulation, and calcium absorption
https://openstax.org/books/concepts-biology/pages/18-key-terms
external fertilization : the fertilization of eggs by sperm outside an animal’s body, often during spawning
https://openstax.org/books/concepts-biology/pages/18-key-terms
fission : (also, binary fission) a form of asexual reproduction in which an organism splits into two separate organisms or two parts that regenerate the missing portions of the body
https://openstax.org/books/concepts-biology/pages/18-key-terms
follicle stimulating hormone (FSH) : a reproductive hormone that causes sperm production in males and follicle development in females
https://openstax.org/books/concepts-biology/pages/18-key-terms
fragmentation : the breaking of an organism into parts and the growth of a separate individual from each part
https://openstax.org/books/concepts-biology/pages/18-key-terms
gastrulation : the process in which the blastula folds over itself to form the three germ layers
https://openstax.org/books/concepts-biology/pages/18-key-terms
gestation : the development before birth of a viviparous animal
https://openstax.org/books/concepts-biology/pages/18-key-terms
gestation period : the length of time of development, from conception to birth, of the young of a viviparous animal
https://openstax.org/books/concepts-biology/pages/18-key-terms
gonadotropin-releasing hormone (GnRH) : a hormone from the hypothalamus that causes the release of FSH and LH from the anterior pituitary
https://openstax.org/books/concepts-biology/pages/18-key-terms
hermaphroditism : the state of having both male and female reproductive structures within the same individual
https://openstax.org/books/concepts-biology/pages/18-key-terms
human beta chorionic gonadotropin (β-HCG) : a hormone produced by the chorion of the zygote that helps to maintain the corpus luteum and elevated levels of progesterone
https://openstax.org/books/concepts-biology/pages/18-key-terms
in vitro : taking place in a test tube, culture dish, or elsewhere outside a living organism
https://openstax.org/books/concepts-biology/pages/18-key-terms
inhibin : a hormone made by Sertoli cells, provides negative feedback to hypothalamus in control of FSH and GnRH release
https://openstax.org/books/concepts-biology/pages/18-key-terms
inner cell mass : the inner layer of cells in the blastocyst, which becomes the embryo
https://openstax.org/books/concepts-biology/pages/18-key-terms
internal fertilization : the fertilization of eggs by sperm inside the body of the female
https://openstax.org/books/concepts-biology/pages/18-key-terms
interstitial cell of Leydig : a cell type found next to the seminiferous tubules that makes testosterone
https://openstax.org/books/concepts-biology/pages/18-key-terms
labia majora : the large folds of tissue covering inguinal area
https://openstax.org/books/concepts-biology/pages/18-key-terms
labia minora : the smaller folds of tissue within labia majora
https://openstax.org/books/concepts-biology/pages/18-key-terms
luteinizing hormone (LH) : a reproductive hormone that causes testosterone production in males and ovulation and lactation in females
https://openstax.org/books/concepts-biology/pages/18-key-terms
menstrual cycle : the cycle of the degradation and re-growth of the endometrium
https://openstax.org/books/concepts-biology/pages/18-key-terms
oogenesis : the process of producing haploid eggs
https://openstax.org/books/concepts-biology/pages/18-key-terms
organogenesis : the process of organ formation during development
https://openstax.org/books/concepts-biology/pages/18-key-terms
ovarian cycle : the cycle of preparation of egg for ovulation and the conversion of the follicle to the corpus luteum
https://openstax.org/books/concepts-biology/pages/18-key-terms
oviduct : (also, fallopian tube) the muscular tube connecting uterus with ovary area
https://openstax.org/books/concepts-biology/pages/18-key-terms
oviparity : a process by which fertilized eggs are laid outside the female’s body and develop there, receiving nourishment from the yolk that is a part of the egg
https://openstax.org/books/concepts-biology/pages/18-key-terms
ovoviparity : a process by which fertilized eggs are retained within the female; the embryo obtains its nourishment from the egg’s yolk, and the young are fully developed when they are hatched
https://openstax.org/books/concepts-biology/pages/18-key-terms
ovulation : the release of an oocyte from a mature follicle in the ovary of a vertebrate
https://openstax.org/books/concepts-biology/pages/18-key-terms
parthenogenesis : a form of asexual reproduction in which an egg develops into a complete individual without being fertilized
https://openstax.org/books/concepts-biology/pages/18-key-terms
penis : the male reproductive structure for urine elimination and copulation
https://openstax.org/books/concepts-biology/pages/18-key-terms