MOD F TECH 38 Digestive System

Question 1

Digestive system

Definition

Answer 1

The organ system including the mouth, teeth, tongue, oesophagus, stomach, intestines and various glands that functions to ingest, digest and absorb nutrients

Question 2

Food Groups

Answer 2

The three basic food groups are :-

•

• Carbohydrates
• Fats
• Proteins

Question 3

Digestive Process

Answer 3

•Ingestion

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•Digestion

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•Absorption

•

•Elimination

Question 4

The Mouth

Answer 4

•Membranes produce mucus

•

•There are also, three pairs of glands which produce up to 1500ml per day, of a complex substance called saliva

•

•Saliva consists of :- Water, Mineral salts, mucus, immunoglobulins, blood clotting factors and the salivary enzymes

Question 5

Tongue

Answer 5

Is a muscular organ which is attached to the hyoid bone and the mandible.

Functions :-

• Organ of taste
• Assists in mastication
• Assists in swallowing

Assists in speech

Question 6

The Pharynx

Answer 6

The Pharynx :-

•The bolus of food is pushed into the pharynx by the tongue [“pharynx” essentially a muscular tube]

Question 7

Epiglottis

Answer 7

The Epiglottis :-

• Is superior to the larynx and the junction of the oesophagus
• On swallowing, the epiglottis blocks the larynx, to allow food to go down the oesophagus without affecting the airway

Question 8

The Oesophagus

Answer 8

•A soft muscular tube [flat] 25 to 30cm long

•

•Runs down the gap in the “C” shaped rings of the cartilage surrounding the trachea and passes through the diaphragm at the level of the 10th thoracic vertebra to become the stomach

•

•The oesophagus, moves the bolus of food towards the stomach by “Peristalsis”

Question 9

The Stomach

Answer 9

•The stomach is the most dilated part of the digestive system, and it can hold up to 1500ml in the adult

•

•The upper opening of the stomach is called the cardiac or lower oesophageal sphincter

•

•The lower opening of the stomach is called the pyloric sphincter

Question 10

Position

The Stomach

Answer 10

The fundus of the stomach lies in the left upper quadrant of the abdomen just inferior to the diaphragm

Question 11

•Food is mixed with gastric juices which contain hydrochloric acid and an enzyme that begins the digestion of food

•

•A lining of mucus prevents the walls of the stomach being digested by the enzyme

•

•The function of the stomach is to churn up the food into a milky substance called “chyme” by mixing it with gastric juices

Question 12

Gastric Juice

Functions of gastric juices

Answer 12

Secreted by special glands in the mucosa and consists of :-

•

• Water
• Mucus
• Hydrochloric acid
• Enzymes
• Gives acid reaction required by the enzymes
• Kills bacteria
• Stops the action of Amylase (enzyme in saliva which breaks down carbohydrates (starch) into simple sugars)
• After 2-6 hours the chyme is passed through the pyloric sphincter into the duodenum

Question 13

The small intestine

Answer 13

•Is continuous with the stomach at the pyloric sphincter and leads into the large intestine

•

• It is a little over six metres long and lies in the abdominal cavity surrounded by the large intestine
• In the small intestine the chemical digestion of food is completed and most of the absorption of nutrient materials takes place

•

•The small intestine is described in three parts, which are continuous with each other

Question 14

Duodenum

Answer 14

•Approx. 25cm long, it curves around the head of the pancreas.

•

•At its midpoint there

is an opening –common

to the pancreatic duct

and the common bile duct

•

•The bile, pancreatic and intestinal juices complete the conversion of the chyme into fats, amino acids and carbohydrates

Question 15

Jejunum and Ileum

Answer 15

•The jejunum is the middle part of the small intestine and is about two metres long. It’s continuous with the….

•

• Ileum or terminal part, which is about three metres long
• Ends at the ileocaecal valve which controls the flow of material from the ileum to the large intestine and prevents regurgitation

Question 16

Jejunum and Ileum

Answer 16

Question 17

Function of Small Intestine

Answer 17

1.Onward movement of its contents which is produced by peristaltic movements

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2.Secretion of intestinal juice

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3.Completion of digestion of carbohydrates, fats and proteins in the epithelial cells of the villi

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4.Protection against infection by microbes that have survived the antimicrobial action of the hydrochloric acid in the stomach

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5.Absorption of nutrient materials

Question 18

Large intestine “Colon

Answer 18

•The large intestine is about 1.5 metres long, and begins at the “caecum” in the right iliac fossa and terminates at the rectum and anal canal deep in the pelvis

•

•It forms an arch around the coiled up small intestine

Question 19

Rectum and Anus

Answer 19

•The colon terminates at the rectum, which is about 13cm in length and leads to the anus.

•

•Defaecation is controlled by the internal and external anal sphincters

Question 20

Functions of Large Intestine

Answer 20

•Absorption

•

•Microbial activity

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•Mass movement

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•Defaecation

Question 21

Accessory Organs

Answer 21

•The liver is the largest gland in the body and can weigh up to 2.3kg in the adult, and is described as having two lobes.

•

•Following absorption in the small intestine the nutrient rich blood passes via the Portal vein to the liver

Question 22

Liver

Answer 22

Question 23

liver

Answer 23

Question 24

Pancreas

Answer 24

•The pancreas is situated posterior to the stomach and anterior to the abdominal aorta and inferior vena cava

•

• It has two main functions………
• Production of pancreatic juice which is secreted into the duodenum via the pancreatic duct

•

•Production of insulin :- Insulin is a hormone produced by specialised cells in the pancreas called the “Islets of Langerhans”

Question 25

Peritoneum

Answer 25

•A serous membrane which lines the abdomen and covers the abdominal organs • * It prevents friction as the organs move against each other and helps to keep them in position * It also carries and supports blood vessels within the abdominal cavity • •It is richly supplied with blood and lymph vessels and contains a considerable number of lymph nodes • •Has the ability to isolate an area of slowly developing inflammation, such as chronic appendicitis, preventing the spread of infection to the rest of the peritoneal cavity

Question 26

Peritoneal Abdomen ## Footnote Organs covered by the peritoneal lining

Answer 26

* Spleen * Liver * Stomach * Gall bladder * Bowel

Question 27

Other Abdominal and Pelvic Organs ## Footnote Although not part of the digestive system the following organs are also within the abdominal cavity :-

Answer 27

* Spleen – peritoneal * Kidneys – retroperitoneal * Bladder and Ureters - retroperitoneal * Urethra – pelvic abdomen * Ovaries, Uterine tubes and Uterus [female] - pelvic

Question 28

Spleen

Answer 28

* Lies in the left hypochondrial region of the abdominal cavity, between fundus of the stomach and the diaphragm * Size varies but usually approx. 12cm long, 7cm wide and 2.5cm thick * Weighs approx. 200g

Question 29

Functions of the Spleen

Answer 29

* Produce new leucocytes (white blood cells) and lymphocytes * Store erythrocytes (red blood cells) * Destroy old red blood cells

Question 30

Kidneys

Answer 30

Question 31

Kidney functions

Answer 31

•Filter blood to remove waste products such as urea • •Regulate water and salt balance • •Excrete urine

Question 32

Ureters, Bladder and Urethra

Answer 32

* Ureters 25cm -30cm long tubes pass from kidneys to the bladder * Bladder is a muscular reservoir bag that holds 300ml urine when full, but can be distended to hold more * Urethra is the canal from the bladder to the outside of the body The bladder lies in the pelvic cavity but rises into the abdomen when full

Question 33

Female reproductive organs

Answer 33

Question 34

The nine regions of the abdominal area

Answer 34