Nervous System, ANS, and Gastrointestinal Physiology Flashcards

Comprehensive vocabulary flashcards covering the autonomic nervous system, spinal cord and nerves, brain anatomy, nervous system disorders, and gastrointestinal anatomy, physiology, and nursing care.

Autonomic Tone

The background resting level of autonomic nervous system activity.

Vasomotor Tone

A sympathetically induced continuous state of partial blood vessel constriction.

Sympathetic Nervous System

The division of the autonomic nervous system responsible for the 'fight or flight' response, characterized by thoracolumbar outflow.

Parasympathetic Nervous System

The division of the autonomic nervous system responsible for 'feed and breed' activities, characterized by craniosacral outflow.

Cholinergic Fiber

A nerve fiber that secretes acetylcholine ($\text{ACh}$) as its neurotransmitter.

Adrenergic Fiber

A nerve fiber that secretes norepinephrine ($\text{NE}$) or noradrenaline as its neurotransmitter.

Muscarinic Receptors

Cholinergic receptors located on target effector organs activated by acetylcholine released from parasympathetic postganglionic fibers.

Nicotinic Receptors

Cholinergic receptors located in autonomic ganglia ($\text{N}_N$) and neuromuscular junctions ($\text{N}_M$).

Agonist

A drug or substance that binds to and activates a specific receptor.

Antagonist

A drug or substance that prevents receptor activation.

Ascending Tracts

Sensory nerve pathways in the spinal cord that carry information upward to the brain, such as the spinothalamic, dorsal column, and spinocerebellar tracts.

Descending Tracts

Motor nerve pathways in the spinal cord that carry signals downward from the brain, such as the pyramidal and extrapyramidal tracts.

Decussation

The crossing over of nerve tracts from one side of the central nervous system to the opposite side.

Reflex Arc

The neural pathway that mediates a reflex response, consisting of a sensory receptor, afferent neuron, efferent neuron, and effector organ.

Cranial Nerves

Twelve pairs of nerves arising directly from the brain and brain stem that supply sensory and motor functions to the head, neck, and viscera.

Dermatome

An area of skin supplied by sensory neurons originating from a single pair of spinal nerves.

Sciatic Nerve

The largest nerve in the body, formed by two nerves bound together, passing along the posterior aspect of the lower limb.

Afferent Nerves

Sensory nerves that transmit nerve impulses from body receptors toward the central nervous system.

Efferent Nerves

Motor nerves that convey nerve impulses away from the central nervous system to muscles or glands.

Neuroglia

Non-neuronal supportive cells in the nervous system that protect, insulate, and nourish neurons.

Neuron Structure

A single nerve cell consisting of a cell body, dendrites that receive impulses, an axon that transmits signals away, axon terminals, and often a myelin sheath with nodes of Ranvier and neurilemma.

Depolarization

The phase of an action potential in which sodium ions ($\text{Na}^+$) move into the cell, making the inside of the cell membrane positive.

Repolarization

The phase of an action potential in which potassium ions ($\text{K}^+$) move out of the cell, returning the inside of the cell membrane to its resting negative state.

Synapse

The functional junction across which a nerve impulse is chemically transmitted from the axon terminal of one neuron across the synaptic cleft to receptors on another neuron.

Cerebral Cortex

The thin outer layer of gray matter covering the cerebrum, responsible for high-level integrative functions.

Broca's Area

The motor speech area of the frontal lobe that coordinates the muscular movements required for speech production.

Diencephalon

The central brain region located between the cerebrum and brain stem, comprising the thalamus and hypothalamus.

Reticular Activating System

A neural network within the brain stem that regulates wakefulness, sleep, and consciousness.

Meninges

The three protective connective tissue layers surrounding the brain and spinal cord: dura mater, arachnoid mater, and pia mater.

Electroencephalogram (EEG)

A graphic recording of the electrical activity of the brain.

Electromyography

A diagnostic procedure used to record and evaluate the electrical activity produced by skeletal muscles.

Myelography

Radiographic examination of the spinal cord and subarachnoid space following injection of a contrast medium.

Intracranial Hematomas

Accumulations of blood in the head following injury, categorized as epidural hematoma (between skull and dura mater), subdural hematoma (beneath dura mater), or intracerebral hematoma (within brain tissue).

Cerebrovascular Accident (CVA)

A stroke caused by impaired blood flow or hemorrhage in the brain, leading to neurological deficit and tissue damage.

Transient Ischemic Attack (TIA)

A brief, temporary episode of neurological dysfunction caused by focal cerebral ischemia without permanent acute infarction.

Akinesia

Complete loss or absence of voluntary muscle movement.

Bradykinesia

Abnormal slowness of physical movement and physical responses.

Aphagia

Inability to swallow food or liquid.

Aphasia

Loss or impairment of the ability to produce or comprehend spoken or written language due to brain injury.

Dysphasia

Difficulty speaking or understanding speech due to brain damage.

Cephalalgia

Medical term for headache or head pain.

Diplegia

Paralysis affecting symmetrical parts of the body, such as both arms or both legs.

Hemiplegia

Paralysis affecting one vertical side of the body.

Paraplegia

Paralysis of the lower portion of the body, including both lower extremities.

Quadriplegia

Paralysis affecting all four extremities and trunk.

Psychosis

A mental health condition characterized by gross impairment in reality testing, such as schizophrenia.

Ingestion

The process of taking food or fluid into the body through the mouth.

Digestion

The mechanical and chemical breakdown of food into smaller nutrients.

Absorption

The movement of digested nutrient molecules from the gastrointestinal lumen into the blood or lymph circulation.

Layers of the Gastrointestinal Tract

The four structural layers of the GI tract wall from inside to outside: mucosa (inner lining), submucosa (connective tissue with blood vessels and nerves), muscle layer (circular and longitudinal smooth muscle), and serosa (outer protective layer).

Enteric Nervous System

An intrinsic nerve network within the gastrointestinal tract (comprising myenteric and submucosal plexuses) that regulates GI motility and secretions.

Peristalsis vs. Segmentation

Peristalsis consists of wave-like contractions that push GI contents forward, whereas segmentation consists of localized back-and-forth contractions that mix contents with secretions.

Paralytic Ileus

The loss of intestinal peristalsis resulting in accumulated food, fluid, and gas, characterized by absent bowel sounds and abdominal distention.

Deglutition

The clinical term for the act of swallowing.

Gastrin

A gastrointestinal hormone released by stomach G cells that increases gastric acid ($\text{HCl}$) secretion and stimulates gastric motility.

Cholecystokinin (CCK)

A hormone secreted by the duodenum in response to fats and proteins that induces gallbladder contraction and stimulates pancreatic enzyme release.

Secretin

A hormone released by the duodenum that stimulates pancreatic bicarbonate ($\text{HCO}_3^-$) secretion to neutralize acidic stomach chyme.

Ghrelin

A stomach-secreted hormone that stimulates appetite and signals hunger before meals.

Leptin

A hormone secreted by adipose tissue that promotes satiety and signals adequate energy stores.

Hematemesis

Vomiting of blood originating from an upper gastrointestinal tract source.

Melena

Dark, black, tarry stool containing digested blood, typically from an upper GI tract source.

Hematochezia

Passage of fresh, bright red blood in the stool, typically indicating lower GI tract bleeding.

Steatorrhea

Pale, bulky, greasy, or oily stool caused by fat malabsorption.

Abnormal Stool Types

Key visible stool alterations including hematochezia (bright red blood), melena (black tarry stool), pale/clay-colored stool (lack of bile), and steatorrhea (bulky greasy stool).

Ascites

Abnormal accumulation of fluid within the peritoneal cavity of the abdomen.

Fecal Impaction

A mass of hardened stool lodged in the rectum or sigmoid colon after prolonged constipation.

Types of Enemas

Solutions administered rectally classified by therapeutic purpose: cleansing enemas (evacuate bowel), oil-retention enemas (soften fecal masses), carminative enemas (relieve gas), medicated enemas (deliver local therapy), and prepackaged enemas.

Stoma

A surgically created opening on the abdominal wall that allows intestinal contents to exit the body.

Ileostomy

An intestinal diversion originating in the ileum that brings small intestine content out through an abdominal stoma, yielding liquid to semi-liquid output.

Colostomy

An intestinal diversion originating in the colon that brings large intestine content out through an abdominal stoma, yielding output that becomes progressively more formed toward the distal colon.

Stoma Assessment

Evaluation of stoma color and tissue health: normal stomas are moist, pink to red; pale/white stomas indicate reduced blood flow; dusky/purple stomas indicate impaired perfusion; brown/black stomas indicate tissue necrosis.

Colostomy Irrigation

The procedure of instilling warm water into a descending or sigmoid colostomy to stimulate regular, predictable bowel evacuation.