Digestive Chp. 24 - A & P ii

Name accesory organs of the digestive system

teeth, gall bladder, tongue, salivary glands, liver, pancreas

Name the intrinsic control and extrinsic control of the GI system

Intrinsic - enteric system

• part of the autonomic nervous system

• coordinates peristalsis (involuntary constriction/relaxation) & regulates local reflexes

Extrinsic - parasympathetic system

• reflexes initiated by sight/smell/taste of food (thinking of a food & ur mouth starts watering) — caused by vagus nerve (X), stimulates mobility & secretion

Function of the Liver

Bile production for digestion/excretion

• neutralizes stomach acid & emulsifies fat

Storage/processing for nutrients

• stores glycogen, copper, iron, fat & vitamins

Hepatocytes

• removes ammonia & converts it into urea - explained more later

Synthesis of cardiovascular molecules

What accessory gland is both exocrine & endocrine?

Pancreas

Exocrine (Acini)

• produces lipases, amylases, & peptidases to break down food (alongside bicarbonated ions)

Endocrine (Islet of Langerhans)

• beta cells - releases insulin

• alpha cells - glucagon

both help regulate glucose metabolism

What can happen when there is no control of bile secretion and pancreatic secretion

Gallstones

Name enzymes that digests food molecules and where it is found

Amalyse - breaks starch to sugar - salivary glands/pancreas

Pepsin - breaks protein into peptides - chief cells in stomach

Lipase - breaks fat into fattyacid/glycerol - made in pancreas but secreted into small intestine

trypsin & chymotrypsin - breaks down protein - created in pancreas but secreted into small intestine

**Trypsinogen only becomes trypsin thru kinase, and chymotrypsinogen only becomes chymotrypsin with the addition of trypsin

Which of the absorbed molecules (thoroughly digested and leaving the GI tract) enter into the blood and which into the lacteal (lymphatic)

Mixing waves

gentle contractions in the stomach that churn the food with gastric secretions. Ingested food is stored and mixed in the stomach, from where it is slowly released into the small intestine as chyme

What organ produces trypsinogen and chymotripsinogen?

Pancreas

Where would you find a bolus?

Mouth

Most of the absorption of food occurs in:

Small Intestine

What cranial nerve is involved regulating the gastrointestinal tract

CN X, Vagus

Lobules and hepatocytes are found in the:

Liver

Parietal cells in the stomach make:

HCI

The epithelium in the oral cavity is:

Stratified squamous

The tunica that is closest to the lumen of the digestive tract is:

Tunica Mucosa

What part of the large intestine is the appendix attached to?

Cecum

What is the average amount of teeth adults have?

32

Which of the lipoproteins is the most dense (has the most protein):
Chylomicrons, VLDL, LDL, HDL?

HDL - 55% Protein 45% Lipids (Phospohlipids/Cholesterol)

LDL - 25% Protein 75% Lipids (Cholesterol)

VLDL - 10% Protein 90% Lipids (Triglycerides)

Chylomicrons - 1% protein 99% lipids (Triglycerides)

Which of the lipoproteins transports cholesterol to cells?

Low density lipoproteins (LDL

Which of the absorbed molecules (thoroughly digested and leaving the
GI tract) enter into the blood and which into the lacteal (lymphatic)

Molecules that enter the blood(most are water-soluble):

• monosaccharides

• amino acids

• vitamins/minerals

Molecules that enter the lymphatic

• fat-soluble vitamins: Vitamin A, E, D & K

• Cholesterol/Phospholipids

• Long-chain fatty acid & monoglycerides

Name enzymes that digests food molecules and where it is found

Mouth:

• Salivary Amylase: Breaks down starch into maltose and maltotriose.

• Lingual Lipase: Initiates digestion of fat.

Stomach:

• Pepsin: Breaks down proteins into peptides.

• Gastric Lipase: Digests fats (triglycerides).

Pancreas:

• Pancreatic Amylase: Breaks down carbohydrates.

• Trypsin & Chymotrypsin: Break down proteins into peptides.

• Pancreatic Lipase: Breaks down fats into fatty acids and glycerol.

Small Intestine:

• Lactase: Breaks down lactose (milk sugar).

• Sucrase: Breaks down sucrose (table sugar).

• Maltase: Breaks down maltose into glucose.

• Peptidases: Break down peptides into amino acids.

List the regions of the digestive tract, from beginning to end

• Mouth (Oral Cavity): Ingestion begins here, with teeth and saliva starting mechanical and chemical digestion.

• Pharynx (Throat): Receives food from the mouth and pushes it into the esophagus.

• Esophagus: A muscular tube that transports food to the stomach.

• Stomach: Mixes food with acid and enzymes.

• Small Intestine: Digests and absorbs nutrients; consists of the duodenum, jejunum, and ileum.

• Large Intestine (Colon): Absorbs water and forms waste (includes cecum, colon, and rectum).

• Rectum: Stores feces before elimination.

• Anus: The exit point for waste

Explain the three types of propulsion through the digestive tract.

• Swallowing: The tongue moves the food bolus into the pharynx. It includes the oral, pharyngeal, and esophageal phases, coordinating muscle groups to move food into the esophagus.

• Peristalsis: involuntary, wave-like, alternating contraction and relaxation of smooth muscles (circular and longitudinal) that push the bolus or chyme forward through the esophagus, stomach, and intestines. It is the primary mechanism for moving food along the GI tract.

• Mass Movements: Specialized, high-amplitude, intense contractions that occur in the large intestine (colon) a few times daily to move feces over long distances toward the rectum. Often triggered after meals.

What are the major tunics of the digestive tract wall, listed from inside to outside?

• Mucosa:

The innermost layer lining the lumen, responsible for secretion and absorption, made of epithelium, lamina propria (connective tissue), and muscularis mucosae (muscle).

• Submucosa:

A layer of connective tissue beneath the mucosa, containing blood vessels, nerves, and lymphatic vessels.

• Muscularis Externa (or Propria):

Consists of inner circular and outer longitudinal smooth muscle layers that control peristalsis (food movement).

• Serosa/Adventitia:

The outermost layer; it's a serosa (visceral peritoneum) for organs within the peritoneal cavity or an adventitia (connective tissue) for those outside, like the esophagus.

Describe the roles of the ENS, CNS, and ANS in controlling the digestive system.

• Enteric Nervous System (ENS): Located in the gut wall, it operates independently to control motility (via the myenteric plexus) and secretion/blood flow (via the submucosal plexus). It contains neurons for local reflexes that regulate digestion and absorption.

• Autonomic Nervous System (ANS): Connects the CNS to the ENS to modulate digestive speed and intensity.

  • Parasympathetic (vagus nerve): Stimulates digestion, increases peristalsis, and boosts secretions.

  • Sympathetic: Inhibits digestive activity during stress or exercise.

• Central Nervous System (CNS): Monitors the gut via sensory signals and controls the esophageal phase and voluntary defecation. It receives sensory info to manage the "cephalic phase" (e.g., salivation, acid secretion triggered by the sight/smell of food).

What chemical mechanisms regulate the digestive system?

Hormones