Digestive, Metabolic, and Urinary Systems Review

Comprehensive flashcards covering the digestive system functions, metabolic pathways, and the anatomy and physiology of the urinary system based on lecture notes.

Ingestion

The taking of food into the mouth, which is then followed by mastication and deglutition.

Mastication

The process of chewing food.

Deglutition

The scientific term for swallowing.

Secretion

The process where cells in the GI tract and accessory organs release a total of $9$ liters per day of water, acids, buffers, and enzymes into the lumen.

Peristalsis

Alternating contraction and relaxation of smooth muscle in the gastrointestinal walls that mixes food with secretions and propels it toward the anus.

Mechanical Digestion

Physical movements of the GI tract, such as the teeth cutting and grinding food and the stomach churning food to mix it with enzymes.

Chemical Digestion

A series of catabolic hydrolysis reactions where enzymes break down large carbohydrates, lipids, proteins, and nucleic acids into smaller molecules.

Absorption

The process where products of digestion enter epithelial cells lining the GI tract lumen by active transport or diffusion to enter blood or lymph.

Defecation

The elimination of indigestible substances and bacteria from the GI tract through the anus in the form of feces.

Mucosa

The innermost moist layer of the GI tract containing a band of muscle called the muscularis mucosae; it functions in secretion, absorption, and protection.

Submucosa

A layer containing many blood and lymph vessels and the submucosal plexus, providing nutrition and protection.

Muscularis externa

A layer dominated by smooth muscle cells and the myenteric plexus that is key in mechanical processing and GI movement regulation.

Serosa

A serous membrane found in the abdominopelvic cavity that reduces friction.

Adventitia

A layer found in the oral cavity, pharynx, esophagus, and rectum that functions as an anchoring layer.

Bolus

A soft, flexible mass of food produced in the mouth through mastication and mixing with saliva.

Uvula

A structure that helps keep food from entering the pharynx early or going into the nasopharynx.

Vestibule

The space between the teeth and the cheeks or lips.

Gustation

The scientific term for the sense of taste.

Filiform papillae

Structures on the tongue that provide friction but contain no taste buds.

Circumvallate (Vallate) papillae

Large structures at the back of the tongue arranged in a V shape, each containing hundreds of taste buds.

Umami

One of the two added primary tastes, described as a pleasant, broth-like or meaty taste sensed in the circumvallate papillae.

Dental Caries

The gradual demineralization of enamel and dentin by bacterial action, commonly called cavities.

Gingivitis

A condition where the gums become red, sore, and swollen, often occurring with the accumulation of tartar.

Periodontitis

A condition where bacteria invade the bone around the teeth, dissolving the bone away after neglected gingivitis.

Parotid gland

The salivary gland responsible for $25\%$ of saliva production and the primary source of salivary amylase.

Mucin

A glycoprotein from the submandibular gland that gives saliva its lubricating action.

Salivary Amylase

An enzyme that breaks down starch into dextrin and maltose; it remains active in the stomach for about an hour before being inactivated by acid.

Lingual Lipase

An enzyme secreted by glands in the tongue that starts the digestion of triglycerides into fatty acids and glycerol.

Parotitis

Inflammation of the parotid salivary gland caused by the mumps virus.

Pharynx

A common passageway for food, fluids, and air consisting of the oropharynx and laryngopharynx.

Esophagus

A collapsible muscular tube about $25\,cm$ long that transports food to the stomach via peristalsis.

Achalasia

The failure of the esophageal sphincter to relax and permit substances to enter the stomach.

Chyme

The liquid mixture of food and gastric juice formed by the muscular action of the stomach.

Intrinsic Factor

A substance secreted by the stomach necessary for the absorption of vitamin $B_{12}$; lack of this factor results in pernicious anemia.

Parietal Cells

Stomach cells responsible for the secretion of hydrochloric acid ($HCl$).

Chief Cells

Stomach cells that secrete pepsinogen, which is activated into pepsin by $HCl$ to digest proteins.

Rennin

An enzyme found in newborns but not adults that acts on the milk protein casein to convert it into a curdy substance.

Cephalic Phase

The phase of gastric secretion initiated by the sight, smell, taste, or thought of food via the Vagus nerve.

Gastric Phase

The phase of gastric secretion triggered by stomach distension, peptides, and low acidity, providing about $2/3$ of the gastric juice released.

Gastrin

A hormone released during the gastric phase that causes the release of enzymes and $HCl$ and increases stomach motility.

Intestinal Phase

The phase where receptors in the small intestine decrease stomach motility to prevent overloading the duodenum.

Secretin

The first hormone discovered; it decreases gastric secretion, increases pancreatic bicarbonate output, and increases bile output from the liver.

Cholecystokinin (CCK)

A hormone that inhibits stomach emptying, stimulates gallbladder contraction to release bile, and triggers pancreatic juice rich in enzymes.

Plicae circulares

Circular folds that increase the surface area of the small intestine for digestion and absorption.

Bile

A substance produced by the liver that emulsifies lipids to increase their surface area, though it is not an enzyme.

Haustra

A series of pouches in the large intestine created by the taeniae coli muscles.

Islets of Langerhans

Endocrine cells in the pancreas that produce insulin (beta cells) and glucagon (alpha cells).

Glycogenesis

The process of converting glucose to glycogen, also known as glucose anabolism.

Gluconeogenesis

The conversion of non-carbohydrate precursors, such as amino acids and lactic acid, into glucose.

Cirrhosis

A chronic liver disease characterized by the replacement of liver cells with fibrous tissue.

Jaundice

A yellowing of the skin and eyes caused by a buildup of bilirubin in the body.

Metabolism

The sum of all chemical reactions in a living organism.

Catabolism

The degenerative process of breaking down complex organic compounds into simpler ones.

Anabolism

The biosynthetic process of synthesizing complex organic molecules from simpler ones.

Glycolysis

The cytoplasmic anaerobic process that converts one glucose molecule ($C_6$) into two pyruvic acid molecules ($C_3$) and produces $2\,ATP$.

TCA Cycle

Also known as the Krebs cycle; a mitochondrial process that transfers hydrogen atoms to coenzymes and produces energy via substrate-level phosphorylation.

Chemiosmosis

The chemical action through a membrane during oxidative phosphorylation that produces $32\,ATP$.

Beta-Oxidation

The process of converting fatty acids into acetyl-CoA fragments for the TCA cycle, yielding high energy.

Chylomicrons

Lipoproteins that carry lipids from the GI tract into the bloodstream.

Low-density lipoprotein (LDLs)

Lipoproteins that carry cholesterol to peripheral tissues; often referred to as 'bad cholesterol.'

Transamination

A metabolic process that attaches an amino group of an amino acid to a keto acid, effectively converting the keto acid into a new amino acid.

Deamination

The removal of an amine group ($NH_2$) from an amino acid, producing a keto acid and toxic ammonia.

Urea cycle

The process in liver cells that converts toxic ammonia into less toxic urea for excretion.

Absorptive State

The metabolic state following a meal when nutrients are being absorbed into the bloodstream, typically lasting about $4$ hours.

Postabsorptive State

The metabolic state where the body relies on internal reserves for energy because no nutrients are being absorbed.

Lipemia

A condition where plasma appears milky due to high levels of chylomicrons after a meal.

Retroperitoneal

The anatomical location of the kidneys, situated between the dorsal body wall and the parietal peritoneum.

Nephron

The functional unit of the kidney responsible for forming urine.

Glomerulus

A network of capillaries where blood filtration occurs due to high pressure created by the narrow efferent arteriole.

Tubular Reabsorption

The selective process in the nephron that returns filtered water and solutes from the tubule cavity back into the blood.

Tubular Secretion

The movement of materials such as hydrogen ions, potassium, and toxins from the blood into the tubular fluid.

Antidiuretic Hormone (ADH)

A hormone from the posterior pituitary that accelerates water reabsorption and is the primary mechanism for controlling blood-water concentrations.

Aldosterone

A hormone from the adrenal cortex that promotes sodium reabsorption and potassium elimination.

Renin

An enzyme released by juxtaglomerular cells that initiates the renin-angiotensin pathway to raise blood pressure.

Trigone

The triangular area in the urinary bladder formed by the entry of two ureters and the exit of the urethra.

Micturition

The scientific term for the expelling of urine from the bladder, also known as voiding.

Albuminuria

The presence of the protein albumin in the urine.

Glucosuria

The presence of glucose in the urine.

Calculi

Insoluble stones formed from solidified urine salts like calcium oxalate.

Gout

A hereditary condition where excessive uric acid in the blood crystallizes and deposits in joints and tissues.