Digestive System part 1 & 2 Flashcards
Two major functions of the digestive system
-Digestion
-Metabolism
Digestion
-Breakdown of ingested food
-Absorption of nutrients into the blood
Metabolism
-Production of cellular energy (ATP)
-Anabolic (build) and Catabolic (break down) pathways
Two main groups of organs
-Alimentary/GI
-Accessory
Alimentary canal
-Continuous coiled hollow tube from mouth to anus
Alimentary tract organs
-Mouth
-Pharynx
-Esophagus
-Stomach
-Small intestine
-Large intestine
-Rectum
-Anus
Accessory organs
-Salivary glands
-Liver
-Gallbladder
-Pancreas
Processes of the mouth
-Mastication of food
-Mixing masticated food with saliva
-Initiation of swallowing by the tongue
-Allowing for the sense of taste
The three regions of the pharynx (superior to inferior)
-Nasopharynx
-Oropharynx
-Laryngopharynx
Nasopharynx
-Air
-Not part of GI
Oropharynx
Posterior to oral cavity
Laryngopharynx
-Where we swallow food
-Below the oropharynx and connected to the esophagus
Pharynx function
-Serves as a passageway for air and food
-Food movement is by alternating contractions of the muscle layers → peristalsis
Which is anterior - the esophagus or trachea?
-Trachea
-Air in the front food in the back
Esophagus
-Runs from pharynx to stomach through the diaphragm
-Conducts food by peristalsis
-Passageway for food only
What are the four layers (tissues) of the alimentary canal organs from innermost to outermost layer?
-Mucosa (helps food slide + traps germs)
-Submucosa
-Muscle layers
-Serosa
What is the name of the sphincter between the esophagus and the beginning of the stomach?
-Cardioesophageal sphincter
Stomach anatomy
-Located on the left side of the abdominal cavity
-Food enters at the cardioesophageal sphincter
Regions of the stomach
-Cardiac region
-Fundus - chemical breakdown
-Body - chemical breakdown
-Pylorus - funnel shaped terminal end
Food empties into the small intestine at the
Pyloric sphincter
Rugae
Internal fold of the mucosa
Stomach functions
Anal sex can’t deliver
-Acts as a storage tank for food
-Site of breakdown
-Chemical breakdown of protein begins
-Delivers chyme (processed food) to the small intestine
What are the specialized cells and tissues of the stomach? All simple columnar epithelium
-Mucous neck cells
-Gastric glands
-Chief cells
-Parietal cells
-Endocrine cells
Mucous neck cells
Produce a sticky alkaline mucus
Gastric glands
Secrete gastric juice
Chief cells
Produce protein digesting enzymes (pepsinogens)
Parietal cells
Produce hydrochloric acid
Endocrine cells
Produce gastrin
What is the main job of the small intestine?
-Major digestive organ
-Site of nutrient absorption into the blood
-Muscular tube extending from the pyloric sphincter to the ileocecal valve
-Suspended from the posterior abdominal wall by the mesentery
Sections of the small intestine
-Duodenum
-Jejunum
-Ileum
What substance enters the small intestine from the gall bladder?
Bile
Chemical digestion in the small intestine
-Source of enzymes that are mixed with chyme
-intestinal cells
-pancreas
Villi of the small intestine
-Fingerlike structures formed by the mucosa
-Absorption
-Gives the small intestine more surface area
Microvilli of the small intestine
-Small projections of the plasma membrane
-Found on absorptive cells
What are lacteals?
Specialized lymphatic capillaries
Sections of the large intestine
-Ascending
-Transverse
-Descending
-Sigmoidal
Functions of the large intestine
-Absorption of water
-Eliminates indigestible food from the body as feces
-Does not participate in digestion of food
-Goblet cells produce mucus to act as a lubricant
Cecum
Saclike first part of the large intestine
Appendix
-Accumulation of lymphatic tissue that sometimes becomes inflamed
-Hangs from the cecum
Salivary gland
-Parotid glands: located anterior to ear
-Submandibular glands
-Sublingual glands
Saliva
-Mixture of mucus and serous fluids
-Helps to form a food bolus
-Contains salivary amylase to begin starch digestion
-Dissolves chemicals so they can be tasted
Pancreas
-Produces a wide spectrum of digestive enzymes that break down all categories of food
-Enzymes are secreted into the duodenum
Endocrine products of pancreas
-Insulin
-Glucagons
The duct that connects the liver to the gall bladder
Common hepatic duct
Liver
-Largest gland in the body
-Located on the right side of the body under the diaphragm
-Consists of four lobes suspended from the diaphragm and abdominal wall
What is stored in the gall bladder and what is its function?
-Bile
-Produced by cells in the liver
Composition of bile
-Bile salts
-Bile pigment
-Cholesterol
-Phospholipids
-Electrolytes
Gall bladder
-Sac found in hollow fossa of liver
-Stores bile from the liver by way of the cystic duct
-Bile is introduced into the duodenum in the presence of fatty foods
-Gallstones can cause blockage
Processes of the digestive system
-Ingestion
-Propulsion
-Peristalsis
-Segmentation
Ingestion
Getting food into the mouth
Propulsion
Moving foods from one region of the digestive system to another
Peristalsis
Alternating waves of contraction
Segmentation
Moving materials back and forth to aid in mixing
Mechanical digestion
-Mixing of food in the mouth by the tongue
-Churning of food in the stomach
-Segmentation in the small intestine
Chemical digestion
-Enzymes break down food molecules into their building blocks
-Each major food group uses different enzymes
Carbohydrates are broken to
Simple sugars
Proteins are broken to
Amino acids
Fats are broken to
Fatty acids and alcohols
Factors that control digestion
-Controlled by reflexes via the parasympathetic division
-Chemical and mechanical receptors are located in organ walls that trigger reflexes
Stimuli
-Stretch of the organ
-pH of the contents
-Presence of breakdown products
Reflexes
-Activation or inhibition of glandular secretions
-Smooth muscle activity
Digestive activities of the mouth
-Mechanical: food is physically broken down by chewing
-Chemical: food is mixed with saliva, breaking of starch into maltose by salivary amylase
Deglutition (swallowing)
Buccal phase
-Voluntary
-Occurs in mouth
-Food is formed into a bolus
-The bolus is forced into the pharynx by the tongue
What two substances are absorbed in the stomach?
-Alcohol
-Aspirin
Protein digesting enzymes
-Pepsin: an active protein digesting enzyme
-Renin: works on digesting milk protein
