Lesson 68: Structure and Function of the stomach

What structure's function and components, including mucosa cells, should students be able to describe?

The stomach wall.

What specific digestive processes are covered regarding the monogastric stomach?

Secretions and motility patterns.

What is another name for the stomach, or simple stomach?

Ventriculus or Gaster.

What type of animals are referred to as 'Simple Stomach' animals?

Monogastric animals.

What is a monogastric animal defined as?

An animal that has a single-chambered stomach.

How do monogastric animals digest food?

In one stomach compartment using gastric acids and enzymes.

Name four examples of monogastric animals.

Humans, pigs, dogs, cats, horses, and rabbits.

What is a characteristic limitation of monogastric animals compared to ruminants?

Limited Fiber Digestion.

What is an example of a fiber-rich food monogastric animals cannot efficiently break down?

Cellulose.

Which monogastric species have an enlarged cecum that aids in partial fiber digestion?

Horses and rabbits.

What primarily drives the digestive process in monogastric animals?

Enzyme-Based Digestion.

What enzyme digests carbohydrates in monogastric animals?

Amylase.

What enzyme digests proteins in monogastric animals?

Pepsin.

What enzyme digests fats in monogastric animals?

Lipase.

Compared to ruminants, how fast is the digestion process in monogastric animals?

Fast Digestion.

Why do monogastric animals have quicker digestion?

Food does not undergo fermentation in multiple stomach chambers.

Most monogastric animals thrive on what type of diet?

Omnivorous or Carnivorous Diet.

What are the main components of the diet for most monogastric animals?

Easily digestible carbohydrates, proteins, and fats.

What is the function of the stomach that allows digestion to proceed gradually?

Food Storage (temporarily holds food).

What is the process of mechanical digestion involving muscular contractions called?

Peristalsis.

What is the semi-liquid substance formed when food is churned and mixed with gastric juices?

Chyme.

In chemical digestion, what enzyme breaks down proteins into peptides?

Pepsin.

What assists in the initial breakdown of fats in the stomach?

Gastric lipase.

Which enzyme continues acting on carbohydrates in the stomach until deactivated by stomach acid?

Salivary amylase.

What stimulates acid secretion and gastric motility?

Hormones such as gastrin.

What controls the release of chyme into the small intestine?

The pyloric sphincter.

Name four main divisions of the stomach.

Fundus, Cardia, Body, Pylorus.

What are the two specific components of the Pylorus division?

Pyloric antrum and Pyloric canal.

Name the two main curvatures of the stomach.

The Greater curvature and The lesser curvature.

What anatomical feature is described as more prominent in the cat stomach?

Angular notch.

What are the internal folds of the stomach wall called?

Rugae (Gastric Rugae).

When might gastric rugae not be prominently seen?

In a distended stomach.

In the dog, where is the stomach located?

Transversely, between Ribs 9 and 12.

In the dog, which parts of the stomach are generally located on the left side?

Fundus and body.

In the dog, which part of the stomach is generally located on the right side?

Pylorus.

In the cat, where is most of the stomach located relative to the midline?

On the left side of the midline.

In the cat, which specific part of the stomach is located on the right side?

Only the Pyloric canal.

What is the mesentery of the stomach referred to as?

The omentum (or omenta, plural).

What membrane lies between the liver and the lesser curvature of the stomach?

Lesser omentum.

What membrane lies between the body wall (roof) and the greater curvature of the stomach?

Greater omentum.

What structure is often referred to as the “abdominal policeman”?

The greater omentum.

Why is the greater omentum called the "abdominal policeman"?

Due to its immune and protective functions.

What function of the omentum involves adipose tissue and helps regulate metabolism?

Fat Storage and Energy Reserve.

What tissue contained within the omentum aids in the immune response?

Macrophages and lymphoid tissue.

What specific action does the omentum perform to aid in healing?

Moves toward sites of injury, infection, or inflammation.

What serious condition does the omentum help prevent the spread of?

Peritonitis (abdominal infections).

Besides support, what medium does the omentum provide passage for?

Blood vessels, nerves, and lymphatics.

What clinical procedure can utilize the greater omentum for surgical repairs?

Omentum grafting.

The ability of the omentum to help contain what limits their spread?

Tumors and abscesses.

Excessive fat deposition in the omentum is linked to what category of disorders?

Obesity-related disorders.

What serious gastric condition is associated with deep (narrow) chested dogs?

Gastric Dilation / Bloat With Volvulus (GDV).

The blood supply to the stomach in dogs and cats primarily originates from what major artery?

Celiac artery.

Name three main branches of the celiac artery that contribute to stomach blood supply.

Hepatic, splenic, and left gastric arteries.

Which arteries provide only a minor blood supply to the stomach?

Short Gastric arteries.

Which pair of arteries anastomose along the lesser curvature of the stomach?

Left Gastric artery and Right Gastric artery.

Which pair of arteries anastomose along the greater curvature of the stomach?

Left Gastroepiploic artery and Right Gastroepiploic artery.

The Hepatic Portal Vein drains blood from almost the entirety of what anatomical structure?

The GI tract.

Name two major tributaries that contribute to the Hepatic Portal Vein.

Splenic vein plus Left gastric vein, OR Gastroduodenal vein plus right gastric vein, OR Cranial mesenteric vein, OR Caudal mesenteric vein.

Sympathetic innervation of the stomach originates from which section of the spinal cord?

Thoracic spinal cord (T5–T12).

Preganglionic sympathetic fibers synapse in which specific ganglion?

The celiac ganglion.

Postganglionic sympathetic fibers travel along which arteries to reach the stomach wall?

Gastric and gastroepiploic arteries.

Parasympathetic innervation of the stomach originates from the dorsal motor nucleus of which nerve?

Vagus n. (in the medulla oblongata).

Where do ganglia related to parasympathetic innervation exist?

In the wall of the stomach.

What effect does sympathetic innervation have on gastric motility?

Inhibits gastric motility (slows digestion).

What effect does parasympathetic innervation have on gastric acid secretion?

Stimulates gastric acid secretion (via activation of parietal cells).

Sympathetic innervation causes what action on the pyloric sphincter?

Contracts the pyloric sphincter (delaying gastric emptying).

Parasympathetic innervation causes what action on the pyloric sphincter?

Relaxes the pyloric sphincter (facilitating gastric emptying into the duodenum).

What negative condition can be caused by excessive vagal stimulation?

Increased acid production, contributing to gastric ulcers and acid reflux.

List the four layers of the stomach wall from inside out.

Mucosa, Submucosa, Muscular layer, Serosa (Visceral peritoneal layer).

What are the folds found in the mucosa and submucosa called?

Gastric Rugae.

Name the three regions of gastric glands.

Cardic gland, gastric gland/fundic glands, and pyloric gland regions.

The inner layer of the muscular layer consists of what type of muscle?

Oblique muscle.

The cardiac and pyloric sphincters are thickenings of which muscular layer?

The circular muscle layer.

What type of epithelium lines the mucosa of the stomach?

Simple columnar epithelium.

The receptive relaxation motility pattern occurs in which part of the stomach?

The proximal stomach (fundus and body).

The frequency of peristaltic contractions in the distal stomach is about how many cycles per minute in most species?

3 cycles per minute.

What hormone is released from G cells in the pylorus that increases gastric motility?

Gastrin.

What triggers the Cephalic Phase of gastric secretion?

The sight, smell, or thought of food.

What triggers the Gastric Phase of gastric secretion?

Presence of food in the stomach (especially proteins).

What is the function of Secretin, Cholecystokinin (CCK), and Gastric Inhibitory Peptide (GIP) when released in the Intestinal Phase?

They inhibit further gastric secretion to prevent over-acidification of the small intestine.

What anatomical structure divides the distal glandular mucosa from the proximal non-glandular mucosa in the horse stomach?

Margo plicatus.