Chapter 26: Digestive System Flashcards
Purpose of the digestive system
Ingest, mixes, transports, and breaks down food mechanically and chemically; absorbs, digested nutrients and expels wastes
Purpose of food
Nutrients to the body —> synthesis
- enzymes
- growth
- cell division
- repair
- heat
GI or digestive tract consists of
- oral cavity
- pharynx
- esophagus
- stomach
- small intestine
- large intestine
- anus
Accessory digestive organs
- teeth
- tongue
- salivary glands
- liver
- gullbladder
- pancreases
Ingestion
Eating ; food or liquid
Motility
Peristalsis and mixing
- the capability of smooth muscles to mix and move the food contents
Secretions
Acids, bile, mucus, digestive enzymes (7L/ day)
Digestion
- mechanical and chemical
Absorption
- nutrients, ions, and fluids
Elimination of wastes/ defecation
Removal of metabolic wastes
Six basic functions of the digestive system
- ingestion
- motility
- secretion
- digestion
- absorption
- elimination of wastes
Oral cavity
- initial site of mechanical and chemical digestion
- formed by lips, checks, hard palate, soft palate, and tongue
- covered by mucous membranes
Vestibule
- the space between the checks (lips) and the gums
Oral cavity proper
- lies in the centre between the manifold and maxillae
Tongue
- accessory organ composed of skeletal muscle covered with mucous membrane (stratified squamous epithelium)
Functions of the tongue
- manipulation of the food
- mixing with saliva
- converting food into the bolts
- assist in swallowing
Salivary glands
- produce saliva (1-2.5 liters)
Saliva functions
- listens ingested materials to become a slick bolus
- moistens, cleansers, and lubricators the structures of the oral cavity
- begins chemical digestion of charbohydrate with amylase
- antibacterial action with lysozymes
- dissolves food so taste receptors on the tongue can be stimulated
Paranoid glands
(25-30% saliva)
- parotid duct
Submandibular glands
60-70% saliva
-submandibular ducts
Sublingual glands
3-5% saliva
- lesser sublingual ducts
Innervation of salivary glands
Both sympathetic and parasympathetic
Salivary amylase
- carbohydrates digestion enzyme in the oral cavity
Lingual Lipase
- lipid/ fat digestion enzyme secreted by lingual glands
Dentin
70% of hydroxyapalatite
Enamel
- calcium phosphate crystals
Pharynx
Naso
Oro
Larygo
- deglutitiom / swallowing
Mesenteries
Are folds of peritoneum that support and stabilize intraperitoid GI tract organs
Peritoneum
Fold each other and other organs of the digestive tract
Greater omentum
- the longest peritoneal fold, extends from the greater curvature of the stomach to cover most of the digestive organs
- fatty apron or “beer belly”
Lesser omentum
- connects the stomach and duodenum from the liver
Mesentery proper
- suspends most of the small intestine from the posterior abdominal wall
Mesocolon
- stretches part of the large intestine to the poster abdominal wall
Peritoneal ligaments
Are folds of the peritoneum that connects structures
Coronary ligament
Liver to diaphragm
Falciform ligament
Liver to abdominal wall
Lienorenal ligament
Spleen to kidney
The mucosa/ innermost lining of the GI tract is composed of
- epithelium
- laminated propria
- muscular is mucosa
Epithelium
- absorbs nutrients and contains enters enteroendocrine cells
Lamina propria
- areolar connective tissue, blood vessels, and lymphatic vessels and contains mucosa-associated lymphatic tissue (MALT)
Muscularis mucosa
- smooth muscle fibers increase surface
Submucosa
- mesh work of collagenous fibres, nerves, and blood vessels
- contains submucosal glands
- highly vascular and contains the submucossl nerve plexus
Submucosal nerve plexus
Submucosa
- a portion of the enteric nervous system (ENS)
- plexus regulates movements of mucosa and vasoconstriction of the blood vessels
- innervates secretory cells of mucosal glands
Muscularis
- consists of two types of smooth muscle: inner circular and an outer sheet of longitudinal fibres
- contains myenteric nerve plexus
Myenteric nerve plexus
- controls GI tract motility (movements)
Serosa
- most superficial layer of the GI tract
- a serous membrane composed or areolar connective tissue and simple sqoamous eptithium (mesothelium)
- secrets serous fluid
- epithelial portion is called viseral peritoneum
Stomach
I shaped, the size of a sausage, lies inferior to the diaphragm in the abdomens epigastric, umbilical and left hypochondriac region
Stomach functions
Digestion - mixes saliva and gastric juice to form chyme
- serves as a reservoir for food before it is released into the small intestine
- secretes gastric juice that contains HCL, pepsin, and instrinsic factors
- secretes gastrin into the blood
The stomach connects
The esophagus to the duodenum
Digestions of … begins in the stomach
Proteins and triglycerides
Digestion of …. Signs in the mouth and continues in the stomach
Carbohydrates
What organ converts semisolid bolus to liquid chyme
Stomach
How much can the stomach accomidate
Up to 6.4 liters of liquid food
Pepsin
Protein digesting enzyme
Gastric lipase
Triglyceride digesting enzyme
Pancreatic Lila’s
Fat digesting enzyme
Four main regions of the stomach
- cardia
- fundus
- body
- pyloric part
Cardia
Initial part of ghenstomach
Fundus
Food storage
Body
Food mixing
Pyloric part
Consists of three regions
- pyloric antrum
- pyloric canal
- pylorus
Pyloric antrum
Connects the body of the stomach
- food mixing
Pyloric canal
Lead to pylorus
Pylorus
Lead to duodenum
Rugae
Mucosal folds
Gastric gland contain three types of exocrine gland cells
- mucous neck cells
- chief cells
- parietal cells
Surface mucous cell
Secretes alkaline fluid containing mucin
Mucous neck cell
Secretes acidic fluid containing mucin
Parietal cell
Secretes intrinsic factor and hypochloric acid
Chief cells
Secretes pepsinogen and gastric lioase
Enteroendocrine cell
Secretes gastrin into the blood
What percentage of digestion is completed in the small intestine
99%
Intestinal juice
- clear, yellow fluid secreted in amount of 1/2 liters per day.
- provides a vehicle for the absorption of substances from chyme
Three regions. Of the small intestine
- duodenum
- jejenum
- ileum
Goblet cells
Mucus
Mucosa
- lined with glands epithelium
- enteroedocrine cells in the small intestinal glands and their secretions
Intestinal glands
Crypts of lieberkuhn
- intestinal juice
Enteroendocrine cells in mucosa
- s cells
- cck cells
- k cells
S cells
Hormone secretion
Cck cells
Cholecystokinin
K cells
Glucose dependent insulinotrphic peptide (GIP)
Peyers patches
- groups of lymphatic aggregated lymphatic follicles
- present in ileum
Duodenal (brunners) gland
- Submucosa
- secretes alkaline mucous
Functions of the large intestine
Haustral churning: contraction and squeezing the contents into the next houstrum
Peristalsis: slower wave of contraction
Mass peristalsis: occurs between the transverse colon and stronger wave
Final stage of digestion
Flatus
Methane gas’s, hydrogen, carbon dioxide (CHO)
What is responsible for fecal odour in protein digestion
Bacteria
- indole, skatol, hydrogen sulphide
Bilirubin
Converted into stercoblin
Stercoblin
- fecal color
- brown
The liver is divided into lobes by the
Falciform ligament
Hepatocytes
Function unit of the liver
- continuously produces 800-1000 mL of bile per day
Functions of the liver
- produces and releases bile
- detoxifies blood
- store access nutrients absorbed by the GI tract
- produces plasma proteins
Gullbladder is attached to
The inferior surface of the liver
Function of the gullbladder
- store and concentrate bile
The cystic duct connescts
The gullbladder to the common bile duct
Three regions of the gullbladder
- neck
- fundus
- body
What preforms endocrine functions
Pancreatic islets
What preforms exocrine functions
Acinar cells secrete pancreatic juices into the duodenum via the main pancreatic duct
