Digestive Flashcards
Peristalsis
Muscular contractions
Motility
Muscular contractions that break up food, mix it with enzymes and move it along; dependent upon physical activity
What does the digestive system secrete?
Digestive enzymes and hormones
How do we absorb nutrients?
Via membrane transport
Mucosa Layer
Innermost epithelial Layer
Faces the lumen
Submucosa Layer
Matrix of fibrous connective tissue embedded with circulatory vessels and billions of neurons
Similar to Skin
Muscularis Layer
Circular, longitudinal smooth muscle
Where peristalsis begins
Serosa Layer
Connective outer support
Also known as visceral peritoneum
Keeps the alimentary canal in place
Serous Membranes
Epithelial with connective support
Secrete lubricating fluids
Peritoneum
Serous Membrane Single Layer (visceral/parietal)
Retroperitoneum
Structures deep to the peritoneum
Not technically within the abdominal cavity
Mesentery
Serous Membrane
Double Layer; Neurovascular
How long is the alimentary canal?
~25 ft long
How long does it take for food to fully digest?
24 to 48 hours
Infection of the Peritoneum
Death within 24 to 48 hours
Nasopharynx
Area of the upper throat that lies behind the nose
Nasal Mucosa
Remove dust and pathogens from the air as it enters through the nose
Nasal Septum
Divides nasal cavity into two
Nasal Conchae
Also known as turbinates; direct air toward the olfactory epithelium
Tonsils
Lymph nodes with the nasopharynx
Auditory (Eustacean) tube
Links the nasopharynx to the middle ear
Hard Palate
Hard part of the roof of the mouth
Soft Palate
Fleshy extension of the hard palate, stops food/liquids from entering the nasopharynx
Uvula
Dangly thing at the back of the mouth
Causes a gag reflex when stimulated
Epiglottis
Stops food/liquids from entering the wind pipe when you swallow
Vocal Cords
Vibrate during phonation to create sound
Cardiac Sphincter
Food must pass through this in order to go from esophagus to stomach
Esophagus
Foods/fluids pass through this via peristalsis
Salivary Glands
Under mucous membrane of mouth, lips, cheeks and tongue
Secrete salivary amylase
Salivary Amylase
Enzyme secreted by the salivary glands for breaking down food
How are extrinsic glands connected to the oral cavity?
Via the parotid, submandibular and sublingual ducts
Esophagus
Muscular tube between the oropharynx and stomach
Where does the esophagus pass through the diaphragm?
At the esophageal hiatus
Function of the Stomach
Mechanically breaks up, liquifies and chemically digests food, proteins and fats
What is the soupy mixture that the stomach creates called?
Chyme
What enzymes does the stomach secrete?
HCl and proteolytic enzymes
Mucous protects stomach lining from these
What does the stomach absorb?
Aspirin, lipid-soluble drugs and alcohol
What doesn’t the stomach absorb?
Nutrients or water
What is the volume of the stomach?
1L
What is Heartburn?
Also known as GERD
When acid touches the cardiac sphincter
What causes GERD?
Over-eating
Overproduction of acids
Hernia’s
How does chyme enter the duodenum?
Through the pyloric sphincter
Define an ulcer
Erosion of epithelial tissue
Painful and often bleeds
Peptic Ulcer
Erosion of Alimentary Mucosa
Irritation by NSAIDS
Esophageal, Gastric and Duodenal
NSAIDS
Non-steroidal anti-inflammatory drugs
Gastritis
Inflamed mucosa
Bleeding ulcer
Erosion to submucosa
Perforating peptic ulcer
Erosion through all four layers
Leads too peritonitis and sepsis
Helicobacter pylori
Associated with gastric ulcers and cancer which can be cured with antibiotics
50% global incidence; 85% assymptomatic
Gastroenteritis causes
Bacterial or Viral
Toxins like Ciguatera
Oral-fecal transmission
Gastroenteritis Symptoms
Diarrhea and vomiting
Gastroenteritis treatment
Hydration and antimotility drugs
Antibiotics like Cipro
Duodenum
First 8 inches of small intestine
Receives ducts from Pancreas and Gall Bladder
Liver gross anatomy
3 lb organ located inferiorly to the diaphragm
4 lobes
Gall bladder adheres to dorsal surface
Liver functions
Bile and plasma protein production Detox Metabolism Nutrient Conversion Stores glycogen, vitamins and minerals
Where is bile stored?
In the Gall Bladder
~500-1000mL secreted by liver daily
Hepatitis
Inflammation of liver from drugs, toxins, infections or trauma
Cirrhosis
Scarring due to chronic inflammation of the liver
Jaundice
Bile pigments released into blood resulting in yellow skin/sclera
Side effect of hepatitis
Juvenile Jaundice
Temporary liver dysfunction at birth
Hepatic Portal System
Drains into the liver resulting in all nutrients passing through the liver before going to the heart
Venous return from gastrointestinal tract
First Pass Effect
Because enteric drugs must pass through the liver they end up being metabolized quickly
Can be bypassed
Gall Bladder and Bile
10cm Long sac on the underside of the liver
Stores and concentrates bile
Gives color to excrement
Bile composition
Minerals, bile acids(salts) and pigments(bilirubin), cholesterol and phospholipids
Color of Bile
Yellow green
How is bilirubin made?
From hemoglobin breakdown
Function of Bile salts/acids
Emulsify fats and aid in their digestion
Pancreas
Retroperitoneal gland posterior to stomach and adjacent to Duodenum
Pancreatic Endocrine function
Secretes insulin and glucagon into blood
Pancreatic exocrine function
Secretes 1500 mL pancreatic juice into duodenum/day
Composition of pancreatic juice
water, enzymes, zymogens and sodium bicarbonate
Pancreatic Duct
Runs the length of the pancreas to open into duodenum
Retinopathy
Damage to eye vessels due to long term diabetes
Difference between Type 1 Diabetes and Type 2 Diabetes
Type 1 is genetic while Type 2 is acquired as a result of a bad diet
3 parts of the small intestine and length of each part
Duodenum (10 inches)
Jejunum (8 ft - upper abdomen)
Ileum (12ft - lower abdomen)
Where does the small intestine end?
At the ileocecal junction with the cecum
How does the small intestine have such large surface area?
Villi (1 mm tall) and Microvilli (1 micron tall)
Function of villi
Contain blood vessels and lymphatics for nutrient absorption
Function of the small intestine
Duodenum: retroperitoneal - receives stomach acids, pancreatic juice and bile
Jejunum and Ileum - add water and enzymes resulting in digestion and uptake of nutrients
6 parts of the large intestine
Cecum and appendix Ascending colon Transverse colon Descending colon Sigmoid colon Rectum
What ends up in the large intestine?
Indigestibles
Constipation
Colon transit time too slow, too much water absorbed
Diarrhea
Colonic transit time too fast, not enough water absorbed
Motility in the colon
Ambulation critical (gotta walk) Fiber important Inhibited by opiates (stops motility)
Function of the large intestine
Remove as much water as possible and leave the salts behind
Define Dysentery
Pathogenic inflammation of the colon
What can cause dysentery?
Viruses, bacteria and parasites (amoebic)
Symptoms of dysentery
Severe diarrhea, fever, cramps and vomiting
Dehydration is major complication
Dysentery treatment
Cipro, Flagyl, IV fluids and antimotility drugs
Define cholera
Bacterial infection of the small intestine
Define Inflammatory Bowel
Chronic inflammation of small intestine and colon (autoimmune)
Examples of Inflammatory Bowel
Crohn's Disease Ulcerative Colitis Ischemic Bowel Irritable Bowel Syndrome Coeliac Disease (gluten sensitivity)
Diverticulosis
Outpouchings of colon wall (inflammation)
Appendix
Attached to cecum
Omentum
Serous Membrane
4 Layers; Support
Double of the mesentery