Digestive System Flashcards Preview

Anatomy (CAM101) > Digestive System > Flashcards

Flashcards in Digestive System Deck (27)
Loading flashcards...

What are the structures in the digestive system

oral cavity, oesophagus, small and large intestine, pharynx, stomach


What are the accessory structures in the digestive system?

Salivary glands, liver, gallbladder and pancreas


What are the functions of the digestive system?

Chemical digestion (stomach)
Mechanical digestion
Secretion (salivary glands)
Food break down (oral cavity)
Storage and elimination
Absorption of nutrients micronutrients, ions and water, reabsorption of most secretions


What type of secretion does the digestion system do?

Exocrine secretion


What does the digestive system secrete and which structures do this?

Mucus, water, HCO3-, bile, H+, ions and water by the salivary glands, liver, pancreas, stomach and small and large intestine

Note: Nearly all water is reabsorbed in small intestine


What are the layers of the digestive tract?

Muscularis externa
Serous membrane


Describe the mucosa

It is the most superficial layer of the digestive tract, it contains loose CT and smooth muscle, contains lymphatic/ immune system cells. The mucosa secretes and absorbs.


Describe the submucosa

Sits below the mucosa of the digestive tract. It is made of CT and used to move and mix contents


Describe the Muscularis externa

Sits below the submucosa of the digestive tract. It is a double layer of loose CT with neurovascular structures


Describe the serous membrane

Epithelium and CT, contains visceral peritoneum on surface of gastrointestinal tract.


Describe the oral cavity

The oral cavity contains the mouth, teeth, salivary glands and is responsible for food mastication. Its functions are mechanical digestion, initiate swallowing and dissolve tastants


Describe the salivary glands

Salivary glands consist of mucus and serous glands. Saliva, water and ions are produced. An enzyme (amylase) dissolves starch. Salivary glands begin chemical digestion


Describe the Pharynx

The pharynx consists of the nasopharynx, oropharynx and laryngopharynx. The pharynx aids with swallowing and is a passage for air.


Describe the Oesophagus

Located in neck, thorax and abdominal cavity. It conveys ingested material to stomach by a muscular tube.


Explain swallowing

Swallowing moves food through the oral cavity to the pharynx then oesophagus and stomach.
Initiated voluntarily, then automatic (brainstem swallowing centre)


Describe the stomach

The stomach stores the meal and chemically and mechanically digests the food. It releases contents to small intestine.
The stomach mixes with food to form chyme (acidic). Secretions from the gastric glands include;
Mucus (to protect stomach from chyme)
Pepsinogen (protein digestion)
Gastric lipase (lipid digestion)


Describe the small intestine

The small intestine accepts food from stomach. it has three components;
Most of the digestion and absorption occurs here (nearly all water is re-absorbed)
The small intestine moves by smooth muscle contraction


Describe the pancreas

The pancreas produces pancreas juice which contains HCO3- and digestive enzymes
Pancreas also has endocrine roles
The pancreas performs much of chemical digestion in lumen of small intestine.


Describe the liver

The liver produces bile and bile salts The bile salts aid digestion and adsorption of fat by emulsifying fats, and solubilising the digestion products (increases surface area)


Describe the gallbladder

The gallbladder stores the bile and bile salts from liver


How does the small intestine increase its surface area?

It has folds of the mucosa snd submucosa. Villi (mucosa layer)
Microvilli on apical surface of epithelial cells


What does the small intestine secrete?

enzymes such as peptidases, various disaccharides and nucleosidases as well as water, ions and mucus.


Describe the chemical digestion that occurs in the small intestine

Phase 1 occurs in the lumen; Enzymes from pancreas (amylase, lipase etc) break covalent bonds in macromolecules to form smaller macromolecules

Phase 2 occurs at brush boarder; intestinal epithelial cell enzymes (peptidases, various disaccharide) complete digestion process


How does absorption occur in the small intestine?

• Simple diffusion
• Facilitated diffusion
• Secondary active transport
• Active transport


How is the digestive system related to the Hepatic portal venous system

Venous blood from the gut containing most absorbed nutrients goes to the hepatic portal vein. This blood them goes to the liver hen hepatic vein, to inferior vena cava, to right atrium.
It goes to the liver first to give it most access to the nutrients


Describe the large intestine

The large intestine includes; appendix, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal
Its function is to storage, absorb water and ions and also to compact the luminal contents


How is the digestive system regulated?

By the ANS.
Parasympathetic ANS increases activity of digestive system
(increases smooth muscle contraction) and promotion secretion