BMS 308 Cumulative Final Exam Review: Digestion

A set of flashcards covering essential vocabulary and key concepts from the BMS 308 course, focusing on the respiratory, digestive, and renal systems.

three main functions of digestion

breakdown of food, absorption of nutrients, elimination of wastes

mechanical digestion

physical breakdown of food (e.g. chewing, churning, peristalsis)

chemical digestion

uses enzymes and acids to break bonds in macromolecules

start of digestion

begins in the mouth, chewing breaks food apart; salivary amylase begins starch digestion

hydrolysis

this type of reaction breaks chemical bonds using water and enzymes, converting polymers into monomers

small intestine

sight of most absoprtion

mechanisms of absorption

active transport, facilitated diffusion, passive diffusion, and endocytosis

monosaccharieds

carb monomer

amino acids

protein monomer

fatty acids, glycerol

lipid monomers

organs of the alimentary canal

Mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus

GI lumen

part of the GI tract “outside” the body (mouth and anus)

accessory digestive organs

teeth, tongue, salivary glands, liver, gallbladder, pancreas

smooth muscle

involuntary, non-striated, slow to contract

skeletal muscle

striated, voluntary, fast contraction

interstitial cells of Cajal

pacemaker cells in the GI tract that generate slow wave potentials for rhythmic contraction

smooth muscle layers of the GI tract

inner circular, outer longitudinal

cross-bridge in smooth muscle

Contraction involves calmodulin binding calcium, activating myosin light-chain kinase, leading to actin-myosin cross-bridge formation

dense bodies in smooth muscle

Anchor actin filaments; during contraction, the cell twists and shortens in a corkscrew shape

Contraction/Relaxation in GI Tract

Circular layer contracts to narrow the lumen; longitudinal layer shortens the segment. Together, they produce peristalsis

bolus

chewed food in the mouth/esophagus

chyme

partially digested food in stomach/small intestine

six essential digestive activities

ingestion, propulsion, mechanical digestion, chemical digestion, absorption, defecation

propulsion

overall GI movement

peristalsis

wave-like contractions pushing food forward

directionality of food movement

Coordinated contractions and sphincters maintain one-way movement; issues like vomiting can reverse this

three actions of mechanical breakdown

chewing, churning, segmentation

segmentation

mixes contents by back-and-forth contractions

peristalsis

propels bolus forward through GI tract

chemical digestion in gut

Enzymatic breakdown of macromolecules, mostly in the small intestine

peritoneum

Double-layered serous membrane that supports and reduces friction between organs

mesentery

A fold of peritoneum that holds intestines in place and provides a route for vessels and nerves

mucosa

made of epithelium, lamina propria, muscularis mucosae

submucosa

The layer of tissue in the gastrointestinal tract that lies between the mucosa and muscularis externa, containing blood vessels, nerves, and lymphatics.

muscularis externa

The layer of muscle in the gastrointestinal tract responsible for peristalsis and segmentation. It typically consists of an inner circular layer and an outer longitudinal layer.

serosa

The outermost layer of the gastrointestinal tract, composed of connective tissue and epithelium, providing protection and support.

GI epithelium

mostly simple columnar; good for absorption and mucus secretion

goblet cells

mucus-secreting cells in mucosa to protect and lubricate lining

lamina propria

Areolar connective tissue in mucosa; contains blood vessels, lymphatics, and immune cells

stretch in the gut

Smooth muscle and connective tissue with collagen and elastin allow expansion and contraction

submucosal plexus

A network of nerves located in the submucosa layer of the gastrointestinal tract that regulates digestive processes and controls gland secretions

myenteric plexus

A network of nerves located between the circular and longitudinal layers of the muscularis externa, responsible for coordinating gastrointestinal motility and regulating muscle contractions

enteric NS

a complex network of neurons governing the function of the gastrointestinal tract, sometimes referred to as the "second brain" due to its autonomy in regulating digestive processes

double circulation organ

receives blood from both the hepatic artery and hepatic portal vein for oxygen and nutrient-rich blood (e.g. liver)

splanchnic circulation

Blood flow to abdominal organs; includes celiac artery, mesenteric arteries, and hepatic portal vein

hepatic portal vein

Delivers nutrient-rich blood from the intestines to the liver for processing

role of pH in GI tract

pH varies by region (acidic in stomach, alkaline in intestines); affects enzyme activity and microbial control

mouth structures

Teeth, tongue, hard and soft palates, uvula, salivary glands

uvula

prevents food from entering the nasal cavity during swallowing

epiglottis function

closes over the trachea during swallowing to prevent aspiration into the lungs

tooth composition

enamel, dentin, pulp

digestive regulation

Controlled by ANS, enteric nervous system, and hormones like gastrin, secretin, CCK

slow wave potentials

rhythmic fluctuations in membrane potential from interstitial cells of Cajal that coordinate contractions

intrinsic Plexi function

Submucosal plexus regulates secretions; myenteric plexus regulates muscle contractions

salivary enzymes

Salivary amylase (starch), lingual lipase (fats); deactivated by stomach acid

salivary control

Triggered by parasympathetic nervous system via cranial nerves (VII and IX)

stomach as food storage

Expands to hold food, slowly releases chyme into duodenum for optimal digestion rate

duodenum as rate limiter

Controls the pace of digestion by regulating gastric emptying via hormones and nervous feedback

gastric secretions

includes HCl, pepsinogen, mucus, intrinsic factor, stimulated by sight/smell of food, stomach digestion

stomach cell types

Parietal cells (HCl, intrinsic factor), chief cells (pepsinogen), mucous cells (mucus), G cells (gastrin)

phases of gastric secretion

Cephalic (sight/smell), Gastric (food in stomach), Intestinal (regulates emptying into small intestine)

liver, gallbladder, pancreas roles

emulsifies fat, stores bile, releases digestive enzymes/hormones, respectively

pancreatic juices

Contain bicarbonate (neutralizes acid), enzymes like trypsin, amylase, lipase, and nucleases