Definitions and descriptions

Definitions and descriptions

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There are currently 66 terms in this directory beginning with the letter D.
Dead space (DED SPAYSE)
1. Anatomic: air that is in the respiratory passages at the end of inhalation and does not participate in gas exchange. 2. Physiological: the volume of nonfunctioning alveoli that decrease gas exchange
Deafness (DEFF-ness)
Impairment of normal hearing; may be caused by damage to the vibration conduction pathway (conduction), the acoustic nerve or cochlear receptors (nerve), or the auditory area in the temporal lobe (central)
Deamination (DEE-am-i-NAY-shun)
The removal of an amino (NH2) group from an amino acid; takes place in the liver when excess amino acids are used for energy production; the amino groups are converted to urea
Decomposition reaction (DE-com-poh-ZI-shun)
A chemical reaction in which bonds in a large molecule are broken and the products are two or more smaller molecules.
Decontamination
Decontamination is the removal or count reduction of microorganisms contaminating an object.
Decubitus ulcer (dee-KEW-bi-tuss UL-ser)
The breakdown and death of skin tissue because of prolonged pressure that interrupts blood flow to the area (Syn.—pressure ulcer).
Defecation reflex (DEF-e-KAY-shun)
The spinal cord reflex that eliminates feces from the colon.
Dehydration
It refers to the loss of body water, with or without salt at a rate greater than the body can replace it. The cause of dehydration is a combination of physiological and disease processes. persons at greatest risk of dehydration include persons with diarrhoea, vomiting, fever, diabetes or infections, impaired level status.
Dehydration (DEE-high-DRAY-shun)
Excessive loss of water from the body.
Deltoid (DELL-toyd)
1. The shoulder region. 2. The large muscle that covers the shoulder joint.
Dendrite (DEN-dright)
The cellular process of a neuron that carries impulses toward the cell body.
Dengue fever
Dengue is a mosquito-borne viral infection causing by the dengue fever virus, whose full life cycle involves the role of mosquito as a transmitter ( or vector) and humans as the main victim and source of infection. Dengue does not spread directly from person to person, it is only spread through the bite of an infected Aedes aegypti mosquito.
Dentigerous cyst
Dentigerous cysts, also called follicular cysts, are slow-growing benign and non-inflammatory odontogenic cysts that are thought to be developmental in origin.
Depolarization (DE-poh-lahr-i-ZAY-shun)
The reversal of electrical charges on either side of a cell membrane in response to a stimulus; negative charge outside and positive charge inside; brought about by a rapid inflow of sodium ions.
Dermatology (DER-muh-TAH-luh-jee)
The study of the skin and skin diseases.
Dermis (DER-miss)
The inner layer of the skin, made of fibrous connective tissue.
Dermoid Cyst
Dermoid cysts are rare masses of the oral cavity derived from ectodermal elements. These are benign, slow-growing tumors that are typically asymptomatic but cause complications of inflammation or dysphagia, dystonia, and airway encroachment due to mass effects.
Detached retina (dee-TACHD RET-in-nah)
The separation of the retina from the choroid layer of the eyeball.
Detrusor muscle (de-TROO-ser)
The smooth muscle layer of the wall of the urinary bladder; contracts as part of the urination reflex to eliminate urine.
Diabetes Mellitus
Diabetes mellitus is a clinical syndrome characterized by persistently high blood glucose values due to deficiency or diminished effectiveness of insulin.
Diabetes mellitus (DYE-ah-BEE-tis mel-LYE-tus)
Hyposecretion of insulin by the pancreas or the inability of insulin to exert its effects; characterized by hyperglycemia, increased urinary output with glycosuria, and thirst.
Diabetic Foot Ulcers
A common surgical complication in diabetic patients. Ulcers can be secondarily infected by staphylococci, streptococci, coliforms, and anaerobic bacteria which can lead to cellulitis, abscess formation, gangrene, and osteomyelitis.
Diabetic Insipidus (DI)
DI is a disorder of water balance caused by non-osmotic renal loss of water leading to excretion of large volume of dilute urine
Diabetic Kidney Disease
This is a clinical diagnosis based on the presence of albuminuria, decreased estimated glomerular filtration rate (eGFR) or both in diabetes. This diagnosis includes diabetic nephropathy which has microalbuminuria (30-300mg/g) and retinopathy in its defining characteristics.
Diabetic Retinopathy
It is a complication of diabetes mellitus in the eyes. It is a chronic progressive sight-threatening disease of the retinal blood vessels associated with the prolonged hyperglycaemia and other conditions linked to diabetic mellitus such as hypertension.
Diagnosis (DYE-ag-NOH-sis)
The procedures used to identify the cause and nature of a person’s illness.
Diaphragm (DYE-uh-fram)
The dome-shaped skeletal muscle that separates the thoracic and abdominal cavities; moves downward when it contracts to enlarge the thoracic cavity to bring about inhalation.
Diaphysis (dye-AFF-i-sis)
The shaft of a long bone; contains a marrow canal filled with yellow bone marrow.
Diarthrosis (DYE-ar-THROH-sis)
A freely movable joint such as hinge, pivot, and ball-and-socket joints; all are considered synovial joints because synovial membrane is present
Diastole (dye-AS-tuh-lee)
In the cardiac cycle, the relaxation of the myocardium.
Differential WBC count (DIFF-er-EN-shul KOWNT)
A laboratory test that determines the percentage of each of the five kinds of white blood cells present in the blood.
Diffusion (di-FEW-zhun)
The process in which there is movement of molecules from an area of greater concentration to an area of lesser concentration; occurs because of the free energy (natural movement) of molecules.
Digestive system (dye-JES-tiv SIS-tem)
The organ system that changes food into simpler organic and inorganic molecules that can be absorbed by the blood and lymph and used by cells; consists of the alimentary tube and accessory organs.
Diploid number (DIH-ployd)
The characteristic or usual number of chromosomes found in the somatic (body) cells of a species (human _ 46).
Disaccharide (dye-SAK-ah-ride)
A carbohydrate molecule that consists of two monosaccharides bonded together; includes sucrose, maltose, and lactose.
Disease (di-ZEEZ)
A disorder or disruption of normal body functioning.
Disinfectant (DIS-in-FEK-tent)
A chemical that destroys microorganisms or limits their growth on inanimate objects.
Disinfection
Disinfection is a specifically targeted antimicrobial treatment with the objective of preventing transmission of certain microorganisms. The purpose of the disinfection procedure is to render an object incapable of spreading infection.
Disorder of Sexual Development (DSD)
DSD formerly known as intersex conditions are classified on the basis of genetics and the state of gonads. They may be caused by virilization 64XX or under virilization 46XY. As well as mosaism (streak Ovary, Ovotestis, dysgentic testis). The most common DSD is Congenital Adrenal Hyperplasia (CAH).
Disseminated Intravascular coagulation (DCI)
Disseminated Intravascular coagulation (DCI) is a pathologic, excessive generation of thrombin and fibrin in the circulating blood. During the process, increased platelet aggregation and coagulation factor consumption occur this does not allow time for compensatory increase in production of coagulant and anticoagulant factors.
Dissociation (dih-SEW-see-AY-shun)
The separation of an inorganic salt, acid, or base into its ions when dissolved in water (Syn.—ionization).
Distal (DIS-tuhl)
Furthest from the origin or point of attachment.
Distal convoluted tubule (DIS-tuhl KON-voh-LOO-ted)
The part of a renal tubule that extends from a loop of Henle to a collecting tubule.
Disulfide bond (digh-SUL-fyed BAHND)
A covalent bond between the sulfur atoms of two amino acids in a protein; helps maintain the three-dimensional shape of the protein (Syn.—disulfide bridge).
Diverticulitis (DYE-ver-tik-yoo-LYE-tis)
Inflammation of diverticula in the intestinal tract.
DNA (Deoxyribonucleic acid)
A nucleic acid in the shape of a double helix. Makes up the chromosomes of cells and is the genetic code for hereditary characteristics.
DNA replication (REP-li-KAY-shun)
The process by which a DNA molecule makes a duplicate of itself. Takes place before mitosis or meiosis, to produce two sets of chromatids (potential chromosomes) within a cell
Dominant (DAH-ma-nent)
In genetics, a characteristic that will be expressed even if only one gene for it is present in the homologous pair of chromosomes.
Dormant (DOOR-ment)
Temporarily inactive; a state of little metabolic activity.
Dorsal (DOR-suhl)
Toward the back (Syn.—posterior).
Dorsal cavity (DOR-suhl KAV-i-tee)
Cavity that consists of the cranial and spinal cavities.
Dorsal root (DOR-suhl ROOT)
The sensory root of a spinal nerve.
Dorsal root ganglion (DOR-suhl ROOT GANG-lee-on)
An enlarged area of the dorsal root of a spinal nerve that contains the cell bodies of sensory neurons
Down syndrome (DOWN SIN-drohm)
A trisomy in which three chromosomes of number 21 are present; characterized by moderate to severe mental retardation and certain physical malformations.
Drug Resistance Tuberculosis (DR-TB)
It is a laboratory diagnosis confirmed after testiing Mycobacterium tuberculosis strains for resistance using rapid genotypic tests (gene-expert) or conventional phenotypic culture and DST
Dry eye
It occurs when there is inadequate tear volume or function.
Duct (DUKT)
A tube or channel, especially one that carries the secretion of a gland.
Ductus arteriosus (DUK-tus ar-TIR-ee-OH-sis)
A short fetal blood vessel that takes most blood in the pulmonary artery to the aorta, bypassing the fetal lungs.
Ductus deferens (DUK-tus DEF-eer-enz)
The tubular organ that carries sperm from the epididymis to the ejaculatory duct (Syn.—vas deferens).
Ductus venosus (DUK-tus ve-NOH-sus)
A short fetal blood vessel that takes blood from the umbilical vein to the inferior vena cava.
Dura mater (DEW-rah MAH-ter)
The outermost layer of the meninges, made of fibrous connective tissue.
Dwarfism (DWORF-izm)
The condition of being abnormally small, especially small of stature due to a hereditary or endocrine disorder; pituitary dwarfism is caused by a deficiency of growth hormone.
Dysmenorrhea
It is a painful menstruation preventing normal activities and requires medication. There are 2 types of dysmenorrhea.
Primary (no organic cause). Typically, in primary dysmenorrhea pain occurs on the first day of menses, usually about the time the flow begins, but it may not be present until the second day. Nausea and vomiting, diarrhea and headache may occur.

Secondary (pathological cause) e.g. PID and uterine polyposis and membranous (castoff endometrial activity shed as a single entity (rare).
Dysphagia
Difficulties in swallowing may arise from problems in transferring the food bolus from the oropharynx to the upper esophagus (oropharyngeal dysphagia) or from impaired transport of the bolus through the body of the esophagus (esophageal dysphagia). The history usually leads to the correct diagnosis.
Dyspnea (DISP-nee-ah)
Difficult breathing.
Dysuria (dis-YOO-ree-ah)
Painful or difficult urination
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