digestive system anatomy

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Questions and Answers

whats alimentary canal

the continuous tube that runs from the mouth to the anus. Together with associated organs such as the pancreas and the gall bladder, the alimentary canal makes up the digestive system. The lining of the alimentary canal is the surface through which nutrients are absorbed.

Mouth cavity

mechanical digestion by teeth; chemical digestion of starch by saliva

salivary glands

three pairs to produce saliva which dissolves food so it can be tasted saliva contains mucus that lubricates the mouth and food and holds food in a lump for swallowing also contains enzyme salivary amylase, which begins starch digestion

pharynx

back of mouth cavity- by moving upwards and backwards, the tongue pushes food into the pharynx for swallowing Signup and view all the answers

oesophagus

carries food from the mouth to stomach. it passes through diaphragm into abdominal cavity Signup and view all the answers

stomach

mechanical digestion by churning action, chemical digestion by pepsin, which begins protein digestion. In infants, rennin coagulates milk protein Signup and view all the answers

liver (not part of alimentary canal)

produces bile, which is stored and concentrated in gall bladder. bile emulsifies lipids in the small intestine (fruit ninja!) Signup and view all the answers

gall bladder (not part of alimentary canal)

stores bile and releases it into the small intestine, where the bile emulsifies lipids Signup and view all the answers

duodenum

first part of small intestine Signup and view all the answers

pancreas (not part of alimentary canal)

produces pancreatic juice containing enzymes for digesting proteins, lipids and nucleic acids Signup and view all the answers

small intestine

about 6m long, its lining secrets intestinal juice, which contains many enzymes. The internal surface is lined with villi for absorption of digested food Signup and view all the answers

appendix

plays a role in immunity and stores useful bacteria Signup and view all the answers

caecum

first part of large intestine Signup and view all the answers

ascending colon, transverse (horizontal) colon and descending colon

longest part of large intestine, absorbs water, minerals and vitamins. Signup and view all the answers

pyloric sphincter

a band of circular muscle that regulates flow of material from stomach to duodenum Signup and view all the answers

rectum

final part of large intestine in which faeces are formed Signup and view all the answers

anus

opening surrounded by the anal sphincter, a muscle that can be voluntarily controlled Signup and view all the answers

Study Notes

Alimentary Canal

The alimentary canal or digestive tract is a continuous tube that winds through the body, beginning at the mouth and ending at the anus.
Consists of different parts of the digestive system
Serves as the pathway for food digestion and absorption.
Responsible for breaking down ingested food into smaller molecules.

Mouth

The initial stage of food processing during digestion.
The mouth contains teeth, which break food into smaller pieces.
The presence of saliva, produced by salivary glands, aids in lubrication and enzymatic breakdown of starches.

Salivary Glands

Three pairs of salivary glands: parotid, submandibular, and sublingual.
Secrete saliva, a fluid containing enzymes like salivary amylase.
Salivary amylase starts breaking down carbohydrates.

Pharynx

Part of the throat.
Connects the mouth to the esophagus and the nasal cavity to the larynx.
Serves as the passageway for both air and food.

Esophagus

Muscular tube connecting the pharynx to the stomach.
Peristaltic movements (muscle contractions) push food down.

Stomach

A J-shaped, muscular organ that acts as a temporary food storage.
Contains gastric juice, including hydrochloric acid and enzymes (like pepsin) for protein breakdown.
Churns and mixes food with gastric juice, forming chyme - partially digested food.
Contains a sphincter called the pyloric sphincter.

Pyloric Sphincter

A muscular band that controls the movement of chyme from the stomach to the small intestine.

Duodenum

The first part of the small intestine that connects to the stomach.
Receives chyme from the stomach and digestive secretions from the pancreas and liver.
Chemical breakdown of food continues here.

Small Intestine

The longest part of the alimentary canal.
Divided into three sections: duodenum, jejunum, and ileum.
Major site for nutrient absorption.
Lined with folds and villi, increasing surface area and maximizing absorption.

Caecum

Small pouch at the beginning of the large intestine.
Connects the ileum of the small intestine to the colon.

Appendix

Small, finger-like projection attached to the caecum.
Believed to have a role in immune function.

Colon

The large intestine consists of three parts: ascending colon, transverse colon, and descending colon.
Responsible for absorbing water and electrolytes.
Contains bacteria that aid in digestion (fermentation).

Rectum

The final section of the large intestine.
Stores feces temporarily.
Contains specialized muscles controlling defecation.

Anus

The opening at the end of the alimentary canal.
Through which feces are eliminated from the body.

Liver (Not part of the alimentary canal)

Produces bile, a substance crucial for fat digestion.
Bile is stored in the gallbladder.

Gallbladder (Not part of the alimentary canal)

Stores and concentrates bile.

Pancreas (Not part of the alimentary canal)

Produces pancreatic juice, containing enzymes (e.g., pancreatic amylase, trypsin, lipase) that break down carbohydrates, proteins, and fats in the small intestine.
Also secretes hormones like insulin and glucagon, which regulate blood sugar levels.

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