Digestive System

Question 1

functions of the digestive system

Answer 1

1. ingestion - taking food in
2. digestion - breaking food down both phys and chem
3. absorption - movement of nutrients into blood stream
4. defecation - waste

Question 2

organs of digestive system

Answer 2

alimenrary canal: (gi tract)

1. mouth
   - (salivary glands)
2. pharynx
3. oesophagus
   - (liver)
   - (lower esophageal sphincter)
4. stomach
   - (pyloric sphincter)
   - (gall bladder)
   - (pancreas)
5. small intestine (Jejunum, ileum)
6. large intestine (appendix, cecum, ascending, transverse, descending, sigmiod, rectum, anus)
   - (sphincters lie between each region)

Question 3

mouth function

Answer 3

mastication (chewing)
mixing food and saliva
initiation of swallowing by tongue
allows sense of taste

Question 4

salivary glands

Answer 4

3 pairs
help form food bolus
contains amylase (enzyme brakedown of starch)
dissolves chems so we can taste

Question 5

oesophagus

Answer 5

around 25cm ling
pharynx-stomach
conducts food by peristalsis (slow rhythmic squeezing)
passage for food only

Question 6

stomach

Answer 6

LEFT side of body (like heart)
food entres caradic sphincter (top)
- empties at pyloric sphincter/valave (bottom)
middle section is acidic (hydrochloric acid; HCL)
- empties in 4–6 hours
both mech and chem happen
delivers chyme (processed food) to SI
- kills microorganisms and acivates enzymes in hydrocholric acid
protein digesting enzymes

Question 7

small intestine

Answer 7

• most chemical digestion occurs/absorption
• muscular tube extending from the pyloric sphincter to the ileocaecal valve and LI
• nearly all food absoprtion here/amino acids, simple sugars, minerals, water soluble vit (B/C).
• lined with projections that increase surface area:
  villi/microvilli
  3 major regions
  1. duodenum
  2. jejunum
  3. ileum

Question 8

1. duodenum

Answer 8

most chem digestion occurs and some absorption takes place

receives chyme from stom, bile from liver/gall and pancreatic juice.

Question 9

bile

Answer 9

made by liver
stored in gall bladder
emulsifies fat - brakedown of fat to smaller globules.
Bile is also released at the same time as pancreatic juice and acts
like a detergent to emulsify or mechanically break down large fat
globules and is also necessary for absorption of fat soluble vitamins.

Question 10

pancreatic juice

Answer 10

contain enzymes which brake down all food groups
- Pancreatic juice is released into duodenum contains enzymes that Help complete digestion of starch (pancreatic amylase)
– Carry out about half of all protein digestion
– Digest fats using lipases from the pancreas
– Digest nucleic acids using nucleases
• Pancreatic juice is alkaline and helps return pH of chyme to a level to
activate intestinal and pancreatic enzymes and protects the intestine

Question 11

2. jejunum

Answer 11

bulk of absorption.
By the time chyme has passed through the jejunum, around 90% of
all available nutrients have been absorbed
into the body

Question 12

3. ileum

Answer 12

longest region of SI

any last nutrients that isnt absorbed are now done here before passing through to LI

Question 13

large intestine

Answer 13

reabsorb fluids, process waste products from the body and prepare for its elimination.
4 parts: ascending, transverse, descending, sigmoid.

Question 14

pancreas

Answer 14

• exocrine: Produces digestive enzymes (pancreatic juice) that breaks down proteins, fats and carbohydrates (chemical digestion)
  • Pancreatic juice is secreted into duodenum
  • Endocrine: hormones; Also produces insulin and glucagon which enter bloodstream and control blood glucose levels
• Bicarbonate produce to neutralise stomach acid

Question 15

liver

Answer 15

located on right side of body.
-  Produces bile/chloestrol (emulsifies
fats by physically breaking large fat
globules into smaller ones)
• Makes important proteins
and hormones.
• Stores glucose (as glycogen) and releases it as needed.
• Stores iron/processes of haemoglobin.
• Breaks down harmful substances
• Clearance of bilirubin – by product of red blood cell breakdown (if there is a build up of bilirubin, become jaundice)
- regulate blood clotting

Question 16

gallbladder

Answer 16

• where bile is stored.
  • When digestion of fatty food is occurring, bile is introduced into the duodenum from the gallbladder.
• mechanically breaks down fat globules.

Question 17

Gastrin (hormone in stomach due to food presence and rising ph)

Answer 17

• Protein-digesting
enzymes
• Mucus
• Hydrochloric acid
2-3 litres of gastric juice produced every day

Question 18

• Mechanical digestion

Answer 18

– Food is physically broken down by chewing
(bile; liver > gall bladder)
(stomach action)

Question 19

• Chemical digestion

Answer 19

• brakes down with saliva
  – Carbohydrate digestion begins by salivary amylase (enzyme; pancreas)
  (mouth, stomach, small intestine)

Question 20

• Hydrochloric acid

Answer 20

makes the stomach contents very acidic
– Activates pepsinogen to pepsin (enzyme) for protein
digestion
– Provides a hostile environment for microorganisms
• Alcohol and aspirin are the only items absorbed in the stomach

Question 21

gastric ulcers

Answer 21

• Erosion of the gastric and duodenal mucosa by acidic
digestive juices
• Causes
– Helicobacter Pylorus infection (bacteria)
(80%)
- bacteria underneath the acid, sitting in pits. it dilautes the acid. causing damage to lining.

• Aggravated by
– Smoking
– NSAIDS
– Stress
– Diet (coffee)
• Symptoms
– Epigastric pain
– Nausea & Vomiting
– Loss of appetite
- reflux , blenching 

Complications
• Perforation, Haemorrhage,
Intestinal Obstruction, Peritonitis.
• If GIT bleeding occurs > haematemesis &or
Melaena (blood in stool, thick)
• OR, if severe bleeding, signs of hypovolaemic shock

Treatment
• Antibiotic therapy ( eradicates H. Pylori and prevents recurrence to 2% - w/o relapse
is 75-90%)
• Lifestyle changes relate to decreasing stress & fatigue.
• Reduce smoking, caffeine intake, alcohol etc.
• Antacids, H2 receptor blockers (Zantac), Proton pump inhibitor (Omeprazole), mucosal
healing agents
• Smaller more frequent meals

Question 22

constipation

Answer 22

ideally in the descending colon
Reduction in frequency in bowel actions.
Causes:
Immobility, sedentary lifestyle
Medications (codeine)
Reduced fluid /fibre intake
Treatment:
• Increase fluid and fibre intake
• Medication-prophylactic (coloxyl if on codeine)
• Medication- varied actions ie Soften faeces, draw water from bowel into stools, enhance peristalsis.

Question 23

Crohn’s Disease

Answer 23

AUTOIMMUNE
• Chronic Inflammation through all layers of any part of the intestinal wall
• White blood cells invade the intestinal lining and produce inflammatory toxins causing chronic tissue swelling, injury and deep ulceration.
• Mal-absorption major problem
- blood in stools

Complications
Obstruction, fistula

Treatment
Medications, diet, surgery

- Symptoms
• anaemia (due to blood loss)
• abdominal cramps and pain
• frequent, watery diarrhoea (may be bloody)
• severe urgency to have a bowel movement
• fever during active stages of disease
• loss of appetite and weight loss
• tiredness and fatigue

Question 24

cholecystitis

Answer 24

Acute or chronic inflammation of the gallbladder commonly associated with impaction of a gallstone in the cystic duct.

Gallbladder becomes distended & filled with bile,
pus & blood.

Signs and Symptoms
Intense pain in the R) upper quadrant- radiating to the back
Jaundice (If a stone obstructs common bile duct)

- treatment
Lithotripsy
Shock wave breaks stone into fragments
Laparoscopic Surgery
• laparoscopic (85%) or open cholecystectomy

Question 25

villi

Answer 25

fingerlike projections formed by the mucosa that line the inner wall of small intestine; increase surface area.

Question 26

microvilli

Answer 26

tiny projections of the plasma membrane (form the brush border on the top of villi)