Case Histories in Human Physiology - Appendix C: Glossary

Glossary - Definitions

pacemaker (p=as´ma´´ker) A group of cells that has the fastest spontaneous rate of depolarization and contraction in a mass of electrically coupled cells; in the heart, this is the sinoatrial, or SA, node.

pacinian corpuscle (pua-sin´e-an) See lamellated corpuscle.

PAH Para-aminohippuric acid; a substance used to measure total renal plasma flow because its clearance rate is equal to the total rate of plasma flow to the kidneys. PAH is filtered and secreted but not reabsorbed by the renal nephrons.

palate (pal´at) The roof of the oral cavity.

palatine (pal´ua-t=1n) Pertaining to the palate.

palmar (pal´mar) Pertaining to the palm of the hand.

palpebra (pal´pue-brua) An eyelid.

pancreas (pan´kre-as) A mixed organ in the abdominal cavity that secretes pancreatic juices into the GI tract and insulin and glucagon into the blood.

pancreatic duct (pan´´kre-at´ik) A drainage tube that carries pancreatic juice from the pancreas into the duodenum of the hepatopancreatic ampulla.

pancreatic islets A cluster of cells within the pancreas that forms the endocrine portion and secretes insulin and glucagon; also called islets of Langerhans.

papillae (pua-pil´e) Small, nipplelike projections.

papillary muscle (pap´u1-ler´´e) Muscular projections from the ventricular walls of the heart to which the chordea tendineae are attached.

paranasal sinus (par´´ua-na´zal si´nus) An air chamber lined with a mucous membrane that communicates with the nasal cavity.

parasympathetic (par´´ua-sim´´pua-thet´ik) Pertaining to the division of the autonomic nervous system concerned with activities that, in general, inhibit or oppose the physiological effects of the sympathetic nervous system.

parathyroid hormone (PTH) A polypeptide hormone secreted by the parathyroid glands. PTH acts to raise the blood Ca++ levels primarily by stimulating reabsorption of bone.

parathyroids (par´´ua-thi´roidz) Small endocrine glands embedded on the posterior surface of the thyroid glands that are concerned with calcium metabolism.

parietal (pua-ri´ue-tal) Pertaining to a wall of an organ or cavity.

parietal pleura (ploor´ua) The thin serous membrane attached to the thoracic walls of the pleural cavity.

Parkinson's disease (par´kin-sunz) A tremor of the resting muscles and other symptoms caused by inadequate dopamine-producing neurons in the basal nuclei of the cerebrum; also called paralysis agitans.

parotid gland (pua-rot´id) One of the paired salivary glands located on the side of the face over the masseter muscle just anterior to the ear and connected to the oral cavity through a salivary duct.

parturition (par´´tyoo-rish´un) The process of giving birth; childbirth.

passive immunity (u1-myoo´nu1-te) Specific immunity granted by the administration of antibodies made by another organism.

pathogen (path´uo-jen) Any disease-producing microorganism or substance.

pectoral (pek´tuo-ral) Pertaining to the chest region.

pectoral girdle The portion of the skeleton that supports the upper extremities.

pedicle (ped´u1-k'l) The portion of a vertebra that connects and attaches the lamina to the body.

pelvic (pel´vik) Pertaining to the pelvis.

pelvic girdle The portion of the skeleton to which the lower extremities are attached.

pelvis (pel´vis) A basinlike bony structure formed by the sacrum and ossa coxae.

penis(pe´nis) The male organ of copulation, used to introduce sperm into the female vagina and through which urine passes during urination.

pennate (pen´=at) Pertaining to a skeletal muscle fiber arrangement in which the fibers are attached to tendinous slips in a featherlike pattern.

pepsin (pep´sin) The protein-digesting enzyme secreted in gastric juice.

peptic ulcer (pep´tik ul´ser) An injury to the mucosa of the esophagus, stomach, or small intestine due to the action of acidic gastric juice.

perforating canal A minute duct through compact bone by which blood vessels and nerves penetrate to the central canal of an osteon; also called Volkmann's canal.

pericardium (per´´u1-kar´de-um) A protective serous membrane that surrounds the heart.

perichondrium (per´´u1-kon´dre-um) A toughened connective sheet that covers some kinds of cartilage.

perikaryon (per´´u1-kar´e-on) The cell body of a neuron.

perilymph (per´u1-limf) A fluid of the inner ear that provides a liquid-conducting medium for the vibrations involved in hearing and the maintenance of equilibrium.

perimysium (per´´u1-mis´e-um) Fascia (connective tissue) surrounding a bundle of muscle fibers.

perineum (per´´u1-ne´um) The floor of the pelvis, which is the region between the anus and the symphysis pubis. It is the region that contains the external genitalia.

perineurium (per´´u1-noor´e-um) Connective tissue surrounding a bundle of nerve fibers.

periodontal membrane (per´´e-uo-don´tal) A fibrous connective tissue lining the dental alveoli.

periosteum (per´´e-os´te-um) A fibrous connective tissue covering the outer surface of bone.

peripheral nervous system (pue-rif´er-al) The nerves and ganglia of the nervous system that lie outside of the brain and spinal cord; PNS.

peristalsis (per´´u1-stal´sis) Rhythmic contractions of smooth muscle in the walls of various tubular organs by which the contents are forced onward.

peritoneum (per´´1u-tuo-ne´um) The serous membrane that lines the abdominal cavity and covers the abdominal visceral organs.

Peyer's patches(pi´erz) See mesenteric patches.

pH A measure of the relative acidity or alkalinity of a solution, numerically equal to 7 for neutral solutions. The pH scale in common use ranges from 0 to 14. Solutions with a pH lower than 7 are acidic and those with a higher pH are basic.

phagocytosis (fag´´uo-si-to´sis) Cellular eating; the ability of some cells (such as white blood cells) to engulf large particles (such as bacteria) and digest these particles by merging the food vacuole in which they are contained with a lysosome containing digestive enzymes.

phalanx (fa´langks), pl. phalanges A bone of a finger or toe.

pharynx (far´ingks) The organ of the digestive system and respiratory system located at the back of the oral and nasal cavities that extends to the larynx anteriorly and to the esophagus posteriorly; also called the throat.

photoreceptor (fo´´to-re-sep´tor) A sensory nerve ending that responds to the stimulation of light.

physiology (fiz´´e-ol´uo-je) The science that deals with the study of body functions.

pia mater (pi´ua ma´ter) The innermost meninx that is in direct contact with the brain and spinal cord.

pineal gland (pin´e-al) A small cone-shaped gland located in the roof of the third ventricle.

pinna (pin´ua) The outer, fleshy portion of the external ear; also called the auricle.

pinocytosis (pin´´uo-si-to´sis) Cell drinking; invagination of the cell membrane forming narrow channels that pinch off into vacuoles. This allows for cellular intake of extracellular fluid and dissolved molecules.

pituitary gland (pu1-too´u1-ter-e) A small, pea-shaped endocrine gland situated on the interior surface of the diencephalonic region of the brain, consisting of anterior and posterior lobes; also called the hypophysis.

pivot joint (piv´ut) A synovial joint in which the rounded head of one bone articulates with the depressed cup of another to permit a rotational type of movement.

placenta (plua-sen´tua) The organ of metabolic exchange between the mother and the fetus.

plantar (plan´tar) Pertaining to the sole of the foot.

plasma (plaz´mua) The fluid, extracellular portion of circulating blood.

plasma cells Cells derived from B lymphocytes that produce and secrete large amounts of antibodies. They are responsible for humoral immunity.

platelets (pl=at-letz) Small fragments of specific bone marrow cells that function in blood coagulation; also called thrombocytes.

pleural (ploor´al) Pertaining to the serous membranes associated with the lungs.

pleural cavity The potential space between the visceral pleura and parietal pleura.

pleural membranes Serous membranes that surround the lungs and provide protection and compartmentalization.

plexus (plek´sus) A network of interlaced nerves or vessels.

plexus of Auerbach (ow´er-bak) See myenteric plexus.

plexus of Meissner (m=1s´ner) See submucosal plexus.

plicae circulares (pli´ce sur-kyuu-lar´=ez) Deep folds within the wall of the small intestine that increase the absorptive surface area.

pneumotaxic area (noo´´muo-tak´sik) The region of the respiratory control center located in the pons of the brain.

polar body A small daughter cell formed by meiosis that degenerates in the process of oocyte production.

polar molecule A molecule in which the shared electrons are not evenly distributed, so that one side of the molecule is negatively (or positively) charged in comparison with the other side. Polar molecules are soluble in polar solvents, such as water.

polydipsia (pol´´e-dip´se-ua) Excessive thirst.

polymer (pol´ue-mer) A large molecule formed by the combination of smaller subunits, or monomers.

polymorphonuclear leukocyte (pol´´e-mor´´fuo-noo´kle-ar loo´kuo-s=1t) A granular leukocyte containing a nucleus with a number of lobes connected by thin, cytoplasmic strands. This type includes neutrophils, eosinophils, and basophils.

polypeptide (pol´´e-pep´t1=d) A chain of amino acids connected by covalent bonds called peptide bonds. A very large polypeptide is called a protein.

polysaccharide (pol´´e-sak´ua-r=1d) A carbohydrate formed by covalent bonding of numerous monosaccharides. Examples include glycogen and starch.

polyuria (pol´´e-yoor´e-ua) Excretion of an excessively large volume of urine in a given period.

pons (ponz) The portion of the brain stem just above the medulla oblongata and anterior to the cerebellum.

popliteal (pop´´lu1-te´al, pop-lit´e-al) Pertaining to the concave region on the posterior aspect of the knee.

posterior (pos-t=er´e-or) Toward the back; also called dorsal.

posterior pituitary (pu1-too´u1-ter-e) See neurohypophysis.

posterior root An aggregation of sensory neuron fibers lying between a spinal nerve and the posterolateral aspect of the spinal cord; also called the dorsal root or sensory root.

posterior root ganglion (gang´gle-on) A cluster of cell bodies of sensory neurons located along the posterior root of a spinal nerve.

postganglionic neuron (p=ost´´gang-gle-on´ik) The second neuron in an autonomic motor pathway. Its cell body is outside the central nervous system and it terminates at an effector organ.

postnatal (p=ost-na´tal) After birth.

postsynaptic inhibition (p=ost´´su1-nap´tik) The inhibition of a postsynaptic neuron by axon endings that release a neurotransmitter that induces hyperpolarization (inhibitory postsynaptic potentials).

preganglionic neuron (pre´´gang-gle-on´ik) The first neuron in an autonomic motor pathway. Its cell body is inside the central nervous system and it terminates on a postganglionic neuron.

pregnancy A condition in which a female is carrying a developing offspring within the body.

prenatal (pre-na´tal) Pertaining to the period of offspring development during pregnancy; before birth.

prepuce (pre´pyoos) A fold of loose, retractable skin covering the glans of the penis or clitoris; also called the foreskin.

presynaptic inhibition (pre´´su1-nap´tik) Neural inhibition in which axoaxonic synapses inhibit the release of neurotransmitter chemicals from the presynaptic axon terminal.

prolactin (pro-lak´tin) A hormone secreted by the anterior pituitary that, in conjunction with other hormones, stimulates lactation in the postpartum female. It may also participate (along with the gonadotropins) in regulating gonadal function in some mammals.

pronation (pro-na´shun) A rotational movement of the forearm in which the palm of the hand is turned posteriorly.

proprioceptor (pro´´pre-o-sep´tor) A sensory nerve ending that responds to changes in tension in a muscle or tendon.

prostaglandin (pros´´tua-glan´din) Any of a family of fatty acids that have numerous autocrine regulatory functions, including the stimulation of uterine contractions and of gastric acid secretion and the promotion of inflammation.

prostate (pros´t=at) A walnut-shaped gland surrounding the male urethra just below the urinary bladder that secretes an additive to seminal fluid during ejaculation.

prosthesis (pros-the´sis) An artificial device to replace a diseased or worn body part.

proton (pro´ton) A unit of positive charge in the nucleus of atoms.

protoplasm (pro´tuo-plaz´´em) A general term for the colloidal complex of protein that constitutes the living material of a cell. It includes cytoplasm and nucleoplasm.

protraction (pro-trak´shun) The movement of a body part, such as the mandible, forward on a plane parallel with the ground; the opposite of retraction.

proximal (prok´-su1-mal) Closer to the midplane of the body or to the origin of an appendage; the opposite of distal.

pseudohermaphrodite (soo´´duo-her-maf´ruo-d1=t) An individual with some of the physical characteristics of both sexes, but who lacks functioning gonads of both sexes; a true hermaphrodite has both testes and ovaries.

pseudopods (soo´duo-podz) Footlike extensions of the cytoplasm that enable some cells (with amoeboid motion) to move across a substrate. Pseudopods are also used to surround food particles in the process of phagocytosis.

ptyalin (ti´ua-lin) An enzyme in saliva that catalyzes the hydrolysis of starch into smaller molecules; also called salivary amylase.

puberty (pyoo´ber-te) The period of development in which the reproductive organs become functional.

pulmonary (pul´muo-ner´´e) Pertaining to the lungs.

pulmonary circulation The system of blood vessels from the right ventricle of the heart to the lungs that transports deoxygenated blood and returns oxygenated blood from the lungs to the left atrium of the heart.

pulp cavity A cavity within the center of a tooth that contains blood vessels, nerves, and lymphatics.

pupil The opening through the iris that permits light to enter the posterior cavity of the eyeball and be refracted by the lens through the vitreous chamber.

Purkinje fibers (pur-kin´je) See conduction myofibers.

pyloric sphincter (pi-lor´ik sfingk´ter) A modification of the muscularis tunic between the stomach and the duodenum that functions to regulate the food material leaving the stomach.

pyramid (pir´ua-mid) Any of several structures that have a pyramidal shape (e.g., the renal pyramids in the kidney and the medullary pyramids on the anterior surface of the brain).

pyrogen (pi´ruo-jen) A fever-producing substance.

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