Digestive System

Question 1

What are the structures in the digestive system

Answer 1

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

Question 2

What are the accessory structures in the digestive system?

Answer 2

Salivary glands, liver, gallbladder and pancreas

Question 3

What are the functions of the digestive system?

Answer 3

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

Question 4

What type of secretion does the digestion system do?

Answer 4

Exocrine secretion

Question 5

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

Answer 5

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

Question 6

What are the layers of the digestive tract?

Answer 6

Mucosa
Submucosa
Muscularis externa
Serous membrane

Question 7

Describe the mucosa

Answer 7

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.

Question 8

Describe the submucosa

Answer 8

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

Question 9

Describe the Muscularis externa

Answer 9

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

Question 10

Describe the serous membrane

Answer 10

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

Question 11

Describe the oral cavity

Answer 11

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

Question 12

Describe the salivary glands

Answer 12

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

Question 13

Describe the Pharynx

Answer 13

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

Question 14

Describe the Oesophagus

Answer 14

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

Question 15

Explain swallowing

Answer 15

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

Question 16

Describe the stomach

Answer 16

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;
HCL,
Enzymes
Mucus (to protect stomach from chyme)
Pepsinogen (protein digestion)
Gastric lipase (lipid digestion)

Question 17

Describe the small intestine

Answer 17

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

Question 18

Describe the pancreas

Answer 18

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.

Question 19

Describe the liver

Answer 19

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)

Question 20

Describe the gallbladder

Answer 20

The gallbladder stores the bile and bile salts from liver

Question 21

How does the small intestine increase its surface area?

Answer 21

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

Question 22

What does the small intestine secrete?

Answer 22

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

Question 23

Describe the chemical digestion that occurs in the small intestine

Answer 23

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

Question 24

How does absorption occur in the small intestine?

Answer 24

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

Question 25

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

Answer 25

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

Question 26

Describe the large intestine

Answer 26

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

Question 27

How is the digestive system regulated?

Answer 27

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