Digestive System I Flashcards
What do we eat and what does it break down into. Know common foods that contain carbs, proteins, and fats
-Carbohydrates (sugars, starches) breaks down to glucose
-Proteins (milk, eggs, meat, cheese, nuts) breaks down to amino acids
-Fats (oils, avocado) breaks down to fatty acids and glycerol
Know the six functions of the digestive system? What are the organs/structures of the alimentary canal? What are the accessory digestive organs? Why is the alimentary canal considered “external”?
Functions:
1. Ingestion
2. Propulsion
3. Mechanical digestion
4. Chemical digestion
5. Absorption
6. Defecation
Organs of alimentary canal:
-GI tract
-Esophagus, stomach, small and large intestines rectum anus
-external because it opens to the outside at each end, the mouth and the anus
Accessory digestive organs:
-salivary glands (parotid, submandibular, sublingual)
-oral cavity
-pancreas
-gall bladder
-liver
Know the three types of movements in the GI tract and their function.
- Peristalsis (wave like) alternatively relax and contract with adjacent sections. Propulsion
- Mass Movements: move lots of material in large intestine. New meal, get rid of old one through defecation.
- Segmentation is localized mixing like a tube of toothpaste squished back and forth. It helps being the mass into contact with enzymes
What is MALT?
Mucosa Associated Lymphatic Tissue such as tonsils, mucosa, Peyer’s Patches and the appendix
Recognize that both the ENS and hormones regulate the nervous system.
Via nervous plexus and hormones
What is the ENS ? What is the function of the ENS? How does the parasympathetic and sympathetic nervous system affect the GI tract?
Enteric Nervous System
“Brain of the Gut”
Parasympathetic-increase activity in GI Tract
Sympathetic-decreases activity in GI Tract
Know the enzymes, what they break down, and where they are produced/active.
Lipase-lipids-sm. intestines
Protease-proteins-stomach/sm. intestines
Trypsin & Chymotrypsin-proteins-sm. intestines
Amylase-carbs- mouith, sm. intestines (maltase,sucrase, lactase)
Nucleas-nucleic acids- sm. intestines
Rennin- breaks down milk protein- as you age you lose production
What is deglutition? Explain the process of swallowing or deglutition? Which part is voluntary and which is involuntary? What is peristalsis? What is the purpose of the upper and lower esophageal sphincters? What is GERD?
Swallowing
Voluntary push: upper esophogral sphincter closed, tongue raised , pushes bolus back, uvula & soft palate elevate to block nasopharynx, larynx moves up & espiglottis moves down to cover trachea
Pharangeal: reflexive grab, pharangeal muscles pull bolus into throat
Esophageal: involuntary peristalsis, esophagus -> lower esophageal sphincter -> stomach
Peristalsis- involuntary consitriction and relaxation of muscles that push bolus forward
GERD- gastroesophageal reflex disease, failure of lower esophageal sphincter, stomach contents reflux up, HCl in esophagus
What is saliva and what are its functions and properties? How is the production of saliva controlled? What enzymes are in saliva?
Lubricate: mucin
Chemical digestion: salivary amylase- starches, maltose, dextose–lingual lipase- lipids, activated in stomach, works in sm. intestines
Cleanses, microbial (antibodies, lysozyme), gustation, mechanical digestion, deglitition
What are the functions of the stomach
Cardia: food enters
Fundus: food storage
Body: mechanical dig (mixing waves, 3 layers: long, circular, oblique), chem dig (cells in gastric pits)
Pyloris: intense mixing, 3 ml chyme into duodenum, gastric emptying
!!For the following cells of the stomach, know what they secrete and how these secretions are controlled: mucous neck cells, parietal cells, chief cells, G cells
Mucous neck cells: secretes mucous
Parietal cells: secretes HCl and intrinsic factor
Chief cells: secretes pepsinogen and gastric lipase
G cells: secrete homrone gastrin
How is the HCl found in the stomach formed? What is the function of the HCl?
Stored as H+ and Cl- in separate cells
Parietal cells form HCl
Breaks down proteins, activates ensymes pepsin & lingual lipase, denatures proteins and cell walls, stimulates hormones (for bile and pancrease)
What is the function of pepsin? What is the function of gastric lipase?
Pepsin: splash peptide bonds in proteins
Gastric lipase: break down triglycerides
What are the three phases of gastric secretion and their functions in the regulation of gastric behavior and motility? How is gastric emptying regulated?
- Cephalic: sensory, emotional
- Gastric: food arrives in stomach, baro/chemoreceptors release gastrin, increases secretion, increases motility
- intestinal: duodenal control, inhibitory to slow exit of chyme, decrease enzyme secretion stomach, decreases motility stomach, CCK and secretin inhibit gastric phase
Gastric emptying regulated by duodenum
Know the location, function and stimulation and/or inhibition of the following hormones: gastrin, secretin and CCK
Gastrin: increases gastric secretion, increases motility, contracts lower esophageal sphincter, relax pyloric sphincter, stsimulates HCL production, inhibited by pH <2, G-cells, target stomach
Secretin: sm. intestines, slows production of acid, inhibits secretion of gastric juice, enhances CCK, stimulates pancreatic juice bicarbonate to buffer chyme, keep pancrease maintenance
CCK: sm. intestines, inhiti stomach, tells gallbladder to release bile, stimulates pancreatic juice, satiety, enhanc secretin, contract pyloric sphincter
