Digestive System (Stomach (Functions (Stores food, churns food (mechanical…
Stores food, churns food (mechanical digestion) into chyme, and begins chemical digestion
Parietal cells - produce hydrochloric acid and intrinsic factor (enables body to absorb vitamin B12 which is used to create erythrocytes).
Chief cells - Produce pepsinogen, which mixes with HCl to create pepsin (enzyme breaks down protein)
Cardiac sphincter - Prevents acid reflux into esophagus
Pyloric sphincter - Regulates amount of chyme entering the small intestine
Rugae - Increases storage capacity of stomach
Mechanical digestion via segmentation, chemical digestion (presence of enzymes), and absorption of nutrients
Duodenal glands - Secrete alkaline mucus which provides a protective coating and neutralizes HCl
Circular folds within the small intestine slow down the passage of chyme and contain villi, which contain microvilli; the function of these folds is to increase the overall surface area of the small intestine to maximize absorption of nutrients.
Intestinal glands - secrete watery intestinal juice
Peyer patches - collection of lymphocytes (MALT)
Ileocecal valve - prevents feces from leaking back into small intestine
Functions of the Digestive System
Breaks down food into smaller pieces in preparation for absorption into blood.
Mechanical digestion - cut food into small pieces
Segmentation - small intestine
Small intestine contracts and relaxes in different areas simultaneously to mix up food.
Mastication - teeth
Churn - stomach
Chemical digestion - uses chemicals (enzymes) to break down food
Occurs in esophagus; alternatively contracts and relaxes to propel food towards the stomach.
Absorbs water and electrolytes
Teniae coli - 3 strips of muscle; contracts and pulls colon into "sacs"
These "sacs" are termed haustra
Epiploic appendages hang on teniae coli
Double layer of peritoneum (made of simple squamous epithelium) lining the cavity of the abdomen and abdominal organs
Connects lesser curvature of stomach to liver
Like an apron; starts at the greater curvature of stomach and drapes over abdominal cavity
Has the ability to wall off infected and inflamed organs
Connects the transverse colon, posterior wall of abdominal cavity, and sigmoid colon
Connects jejunum and ileum of small intestine
Holds organs in place, provides space for blood vessels and nerves, and stores fat
Accessory Digestive Organs
Organs found alongside the GI tract
Liver, gallbladder, submandibular salivary gland, sublingual salivary gland, parotid salivary gland, pancreas
filters toxins, stores glucose (glycogen), makes bile (stored in concentrate in gallbladder and is used to emulsify fat), stores vitamins, processes fats and amino acids, makes blood protein (albumin, fibrinogen, globulin)
Hepatic Portal Circulation
Aorta - delivers O2 rich blood to liver and digestive organs - capillaries in the organs deliver oxygen and pick up nutrients - hepatic portal vein delivers O2 poor blood & nutrients to liver - liver capillaries filter out toxins from blood before they get delivered in systemic circulation - hepatic vein delivers blood to inferior vena cava and back to heart
Pancreatic Acini - exocrine glands secretes 22+ enzymes to enter duodenum
Pancreatic ducts - produce bicarbonate (alkaline solution) to help neutralize acid in the digestive tract
Rectum & Anal Canal
Rectum - stores and expels feces
Anal canal - secretes mucus to provide lubrication; contains an internal sphincter (made of smooth muscle - involuntary) and an external sphincter (made of skeletal muscle - voluntary)
Long tube of the gastrointestinal tract
oral cavity - pharynx - esophagus - stomach - small intestine - large intestine - rectum - anus