Respiratory and Digestive System Flashcards

Comprehensive vocabulary flashcards covering the regulation of breathing, the anatomy and physiology of the digestive system, and metabolic states.

Dorsal Respiratory Group (DRG)

Located in the medulla, it regulates inspiration by controlling the inspiratory muscles, specifically the diaphragm.

Ventral Respiratory Group (VRG)

Located in the medulla, it primarily controls forced expiration by stimulating the intercostal and abdominal muscles.

Pontine Respiratory Group (PRG)

Located in the pons, it adjusts the rate and pattern of breathing by influencing the DRG and VRG in response to sensory stimuli.

Inflation reflex

A mechanoreceptor response where over-inflation of the lungs triggers the inhibition of inspiratory centers and the excitation of expiratory centers.

Central chemoreceptors

Located in the medulla, these receptors respond to chemical changes in the cerebrospinal fluid, specifically monitoring $Pco_2$ via pH levels.

Peripheral chemoreceptors

Receptors located in major blood vessels like the carotid and aortic arteries that monitor $Po_2$ levels.

Irritant receptors

Free nerve endings in the epithelial lining of airways that respond to smoke, dust, or chemical fumes and can initiate coughing or bronchoconstriction via the vagus nerve.

Digestion

The chemical breakdown of food into absorbable bits.

Mastication

The process of chewing food to increase its surface area in the oral cavity.

Bolus

A compacted mass of food prepared for swallowing.

Peristalsis

Sequential waves of circular muscle contractions that force food down the GI tract.

Segmentation

Fragmenting food in the small intestine through contractions that have no propulsive pattern, intended to increase mixing.

Parietal Cells

Gastric gland cells that secrete HCl (to kill pathogens and activate enzymes), Intrinsic Factor (for Vitamin $B_{12}$ absorption), and Ghrelin.

Chief Cells

Gastric gland cells that secrete pepsinogen (the inactive zymogen form of pepsin) and gastric lipase.

Chyme

The mixture of processed food, gastric secretions, and acids that enters the duodenum from the stomach.

Bile Salts

Liver-produced substances stored in the gall bladder that emulsify fats into tiny micelles to increase surface area for enzyme action.

Secretin

A hormone released in response to low pH that increases pancreatic and liver activity while decreasing stomach motility and secretions.

Cholecystokinin (CCK)

A hormone triggered by lipids and proteins in the small intestine that increases the activity of the pancreas and gall bladder.

Glycogenesis

The process by which the liver and skeletal muscles convert glucose into stored glycogen.

Gluconeogenesis

The metabolic process of producing glucose from non-carbohydrate molecules.

Absorptive State

The anabolic state lasting 3-4 hours after ingestion where nutrients are plentiful and glucose serves as the primary energy source.

Post-absorptive State

The catabolic state between absorption periods where energy stores are mobilized through glycogenolysis and gluconeogenesis.

Insulin

A hormone secreted by Beta cells of the pancreas that promotes the synthesis of energy storage molecules and glucose uptake by cells.

Glucagon

A hormone secreted by Alpha cells of the pancreas that promotes the mobilization of energy storage molecules during the post-absorptive state.