GI Tract A&P and Esophagus

hollow, esophagus, small, large, liver, exocrine

GI Tract (Alimentary Canal)

• ___________ Tube → extends from mouth to anus

  • Mouth → __________ → stomach → ______ intestine → ________ intestine → rectum → anus

• Accessory Organs

  • ______

  • Gallbladder

  • ____________ Pancreas

mechanical, chemical, food, water, wastes

Functions of Digestive System

• Performs ____________ and ____________ breakdown of ingested food

• Prepares _____ for uptake by the body’s cells

• Provides body _______

• Eliminates _________

chewing, mucus, bile, pancreas, storage, fluid, solid

Function of the Digestive System

• Mouth

  • _________

• Stomach

  • Food mixed with acid, _______, and enzymes

• Small intestine

  • _____ and enzymes secreted by liver

  • Enzymes secreted by the __________

  • Absorption

• Liver

  • Processing and ___________ of nutrients

• Large Intestine

  • Non-absorbed substances continue to pass

  • ______ absorbed

• Rectum

  • ________ waste eliminated

hormones, motility, autonomic, enteric, voluntary

Digestive System Control

• Ingested substances trigger ___________ that stimulate or inhibit

  • Muscular contractions (GI __________)

  • Secretion of substances that aid in digestion

• Autonomic Nerves

  • Extrinsic → ____________ nerves

  • Intrinsic → autonomic nerves AKA ____________ nervous system

• Chewing, swallowing, and defecation are only part under ___________ control

sympathetic, vertebral, ganglia, splanchnic, outlying, norepinephrine, epinephrine, inhibits

Sympathetic Autonomic Innervation of the Abdomen and Pelvis

• ______________ Trunks

  • Run along both sides of ___________ column (from base of skull to coccyx)

  • Contain sympathetic ____________

• ______________ nerves (Sympathetic)

  • Thoracic, lumbar, sacral

• __________ ganglia

  • Celiac, mesenteric

• Neurotransmitter

  • Mostly ____________

  • Some _____________

• Action

  • ____________ GI activity

vagus, splanchnic, pelvic, acetylcholine, increases

Parasympathetic Autonomic Innervation of the Abdomen and Pelvis

• ___________ Nerve

  • Innervates mostly foregut and midgut

• ____________ nerves (parasympathetic)

  • __________ → innervates mostly hindgut

• Neurotransmitter → ______________

• Action

  • _____________ GI activity

Epithelium, Lamina Propria, connective, lymphoid, muscularis, smooth, mucosal, mucus, infectious

Histology of the GI Tract → Mucosa

1. ______________

2. __________ ___________

   a. Loose _____________ tissue

   b. Contains capillaries and ____________ tissue

3. ____________ mucosa

   a. Thin Layer of ___________ muscle

   b. Promotes ____________ movement

• Functions

  • Secrete _________, digestive enzymes, and hormones

  • Absorb digested products

  • Protect against ___________ disease

connective, follicles, nerve, support, GI glands, lumen

Histology of the GI Tract → Submucosa

• __________ tissue

• Contains blood and lymph vessels, lymphoid ____________, and ___________ fibers

• Main Functions

  • Provides __________ to the mucosa

  • Houses __ _________ with ducts extending to ________

smooth, circular, longitudinal, segmentation, peristalsis

Histology of the GI tract → Muscularis Propria

• ____________ Muscle

  • Inner ____________ muscle

  • Outer ______________ muscle

• Main function

  • Responsible for _______________ and ______________

intraperitoneal, squamous, retroperitoneal, serosa, adventitia, esophagus, fibrous

Histology of the GI Tract → Serosa (Visceral Peritoneum)

• _______________ Organs → connective tissue covered with ___________ epithelial cells

• ______________ organs → _______ on parts facing peritoneal cavity and _____________ on parts against the body wall

• Serosa is replaced by an adventitia in the _____________ (__________ connective tissue)

Enteric Nervous System

Regulates motility reflexes, blood flow, absorption, secretions, and immune response

Submucosal Plexus (Meissner plexus)

Enteric Nervous System Plexus

• located in the submucosa

• Controls GI secretion and local blood flow

myenteric plexus (Auerbach plexus)

Enteric Nervous System Plexus

• Between inner circular and outer longitudinal muscles of the muscularis propria

• Controls GI movements

Subserosal plexus

Enteric Nervous System Plexus

• Located beneath the serosa

Subserosal Plexus

1

Myenteric plexus (Auerbach plexus)

2

Submucosal plexus (Meissner plexus)

3

saliva, taste buds, olfactory

Mouth

• Reservoir for chewing and mixing of food with ________

• Digestion begins in the mouth, with chewing and salivation

• ______ _____ → identify salty, sour, bitter, and sweet tastes when stimulated

• ___________ nerves (smell)

parotid gland

1

submandibular gland

2

sublingual gland

3

bicarbonate, amylase, carbohydrate, mucin, A, infection, fluoride, parotid, submandibular, sublingual

Saliva

• Composed of water, sodium, ___________, chloride, potassium, and salivary a-____________

  • pH around 7.4

  • a-amylase (___________ digestion)

• Contains _________ and Ig_ → helps prevent _________

• Absorbed __________ from diet secreted in saliva

  • Helps prevent tooth decay

• Controlled by sympathetic and parasympathetic fibers

  • CN IX (glossopharyngeal) = __________ gland

  • CN VII (facial) = _____________ and ____________ glands

muscular, striated, smooth, cricopharyngeal, air, regurgitation

Esophagus

• Hollow __________ tube (25-27 cm long)

• 1/3 _________ and 2/3 __________ muscle

• Upper esophageal sphincter (_____________ muscle)

  • Prevents entry of ____ into the esophagus during respiration

• Lower esophageal sphincter (LES)

  • Prevents ______________ from the stomach

oropharyngeal, voluntary, involuntary, esophageal, primary, secondary, independent

Swallowing

• Phases

  • _____________ (voluntary/involuntary)

    • Food chewed and bolus forced posteriorly (____________)

    • Sensory impulses sent via CN 5 and 9 → motor impulses sent via CN 5, 9, 10, 12 (_____________)

  • _______________ (involuntary)

• Peristalsis

  • ___________ → immediately follows the oropharyngeal phase of swallowing

  • _____________ → bolus of food becomes stuck in the esophageal lumen, a wave of contraction and relaxation occurs that is ____________ of voluntary swallowing

regurgitation, cholinergic, gastrin, nonadrenergic, noncholinergic, secretin, vagus

Lower Esophageal Sphincter (LES)

• Prevents _______________ from the stomach

  • Barrier between the stomach and the esophagus

• Control

  • Increase sphincter tone

    • _____________ vagal stimulation

    • __________ (digestive hormone)

  • Relax sphincter tone

    • ____________, ________________ vagal impulses

    • Hormones: progesterone, ___________, and glucagon

  • Mediation of relaxation during swallowing → _______ nerve