Digestive Flashcards
What is the overall purpose of the digestive system?
Extract nutrition
Remove waste
What does the mouth do?
Teeth mechanically break down food
Tongue mixes food + saliva into a bolus
Saliva contains amylase to begin chemical digestion
What does the pharynx do (digestive)?
Muscular tube from mouth to oesophagus
Rhythmic contractions = peristalsis to move food bolus
What does the oesophagus do?
Muscular tube to stomach
Moves bolus via peristalsis
Lower oesophageal sphincter prevents stomach content back flow
What does the stomach do?
Secretes gastric juices containing hydrochloride acid and pepsin to chemically digest
Muscular wall mixes juices with food = chyme
What is reflux?
When the lower oesophageal sphincter is weak or too relaxed stomach contents can back flow into the oesophagus
SX: heartburn, regurgitation, hoarse, cough
What is a peptic ulcer?
Sores on the stomach lining
Usually caused by H. Pylori infection or NSAID use
SX: heartburn, indigestion, nausea, GI bleed
What does the small intestine do?
Duodenum: receives digestive enzymes from the pancreas and bile from the liver/gall bladder and mixes with chyme
Jejenum: absorbs nutrients
Ileum: further absorption including B12, bile salt, water and electrolytes
Contains villi to increase surface area for absorption
What is gastroenteritis?
Inflammation of stomach or intestines caused by an infection
SX: D+V, nausea, pain, fever
What is a hernia?
A bulge where an organ or tissue protrudes through a weakened area.
Commonly inguinal (groin/scrotum) and hiatal (stomach through diaphragm)
May become strangulated causing ischemia, necrosis or obstruction
What does the liver do (digestive)?
Produced bile to digest fat
Metabolises nutrients from small intestines
Detoxification
Stores vitamins and minerals
Produces clotting proteins
What is cirrhosis?
Chronic condition of scarring on the liver causing impaired function
Caused by hepatitis, alcohol, fatty liver disease
Liver gets repeatedly injured —> tries to repair resulting in inflammation and scarring —> lots of scarring forms nodules
What is hepatitis?
Inflamed liver
Caused by virus, medication, alcohol or autoimmune disease
SX: jaundice, pain, n+v, dark urine
What does the gall bladder do?
Stores and concentrates bile from the liver
Ejects it into the small intestine via the common bile duct
What are gallstones?
Hard collections of bilirubin or fat in the gallbladder or bile duct
SX: right upper quadrant pain, usually after a meal/at night, n+v
What does the pancreas do (digestive)?
Release digestive enzymes into the duodenum (exocrine)
Releases bicarbonate to neutralise content from the stomach as it enters small intestine
What does the large intestine do?
Absorbs water and electrolytes from undigested food to form faeces
Houses bacteria that ferments fibre and produces vitamins
What does the rectum do?
Stores faeces and excretes out anus
What is pancreatitis?
Inflammatory process damages pancreatic tissue and can block ducts
Caused by alcohol, obesity, infection, trauma, medications, gall bladder issues
SX: pain with eating that radiates into the back, n+v, weight change, bowel change, fever
What is gastritis?
Inflamed stomach lining
Caused by infection, NSAID, alcohol, stress, autoimmune
SX: pain, n+v, indigestion, bloat, reduced appetite
What are the 4 stages of digestion?
Mechanical - teeth grind, bolus formed, chyme mixed
Chemical - enzyme and chemical
Absorption - villa absorb into blood
Elimination
What is chemical digestion?
Enzyme or chemical action
Saliva has amylase to break down carbohydrate into sugars
Stomach has HCl and pepsin to break down protein into peptides
Pancreas secretes amylase, lipase and protease
Bile breaks down fat
Describe the abdomen
Between diaphragm and pelvic brim
Lined with two layered peritoneum
Outer parietal layer adhered to wall
Inner visceral layer wraps around organs
Organs attached to rear wall via mesentery (also has vessels, fat and nerves)
Retroperitoneal at posterior side
Quadrants divide space into four
What are macronutrients?
Fatty acids, carbohydrates and proteins
What are carbohydrates?
Chains of C, O and H that the body uses for energy
Generally sugars, starches and fibre
Monosaccharides are simple sugars used for energy (glucose)
Disaccharides (lactose)
Polysaccharides are complex sugars which undergo hydrolysis before being used for energy
What are fatty acids?
Used for energy, hormones, supports vitamins, builds cell membranes
Saturated and unsaturated
What is protein?
Chains of amino acids and peptide bonds that the body uses for energy, growth and repair
What are micronutrients?
Vitamins (fat soluble are D, E, K, A)
Minerals - macro and trace
Which organs regulate BSL?
Liver
Pancreas
Muscle
Describe the process of BSL control
Food is consumed and GI breaks down carbohydrates into glucose which is absorbed into the blood stream in the small intestine raising the BSL
Pancreas beta cells release insulin to move glucose into cells. It also promotes the liver to store glucose as glycogen and stops the liver from producing glucose itself. The BSL eventually drops
When BSL low again, pancreas alpha cells release glucagon which stimulates liver to release stored glycogen as glucose and BSL rise again
What is glycogenolysis?
The process of glycogen being converted to glucose
What other hormones may influence BSL?
Cortisol, adrenaline and growth hormone can increase BSL during stress, exercise or fasting via triggering gluconeogenesis
What is gluconeogenesis?
Process of the liver producing glucose from a non-carbohydrate source
What is normal BSL?
4.0-8.0 mmol
What is cellular respiration?
Process of cells converting glucose into ATP
1. Glycolysis: glucose converted into pyruvate (in cytoplasm)
2. Citric Acid / Krebs Cycle: pyruvate converted into electrons (in mitochondria)
3. Oxidative Phosphorylation / Electron transport chain: electrons passed down protein chain releasing energy and chemiosmosis occurs (in mitochondria)
What is the cellular respiration equation?
Glucose + O2 —> CO2 + water + ATP
How do paediatrics digestive system differ?
Reduced ability to store glucose so become hypoglycaemic more rapidly
High metabolic rate needs plenty of glucose
Oesophageal sphincter has reduced tone so high incidence of regurgitation
How does the geriatric digestive system differ?
Reduced oesophageal sphincter = reflux
Reduced GI mobility = constipation and reduced appetite
Weak stomach lining = prone to ulcer
Weak colon lining = diverticulitis
Reduced absorption = malnutrition
What is appendicitis?
Inflamed appendix
Caused by blockage or lymphoid follicle
SX: lower right quadrant pain worsens with strain, low appetite, n+v, fever, bowel change, distension
What is a GI bleed?
Any bleed from the digestive tract
Multiple causes
SX: hematemesis (bloody vomit), melena (dark stool), hematochezia (bright red stool), pain, fatigue, pale, dizzy, low BP, high HR
