Digestive System Flashcards
Taking in food
Ingestion
Ingestion is facilitated by?
Mouth, pharynx, esophagus
Breaking food into nutrient molecules
Digestion
Digestion is facilitated by?
Mouth and small intestine
Mechanical digestion through?
Chewing
Chemical digestion through?
Amylase
Facilitates final digestion
Small intestine
Temporary storage for food
Stomach
Movement of nutrients into the bloodstream
Absorption
Absorption is facilitated by the?
Small intestine and large intestine
Extracts nutrients and minerals from digested food in intestine
Small intestine
Absorbs leftover nutrients from the SI, watery absorption
Large intestine
Excretes to rid the body of indigestible waste; contains bacteria, viruses, and other unnecessary materials in the body
Defecation
Connects the L.I. to the anus
Rectum
Exit point of material
Anus
Two main groups of organs
- Alimentary canal (Gastrointestinal or GI tract)
- Accessory digestive organs
Continuous, coiled, hollow tube that runs through the ventral cavity from stomach to anus
Alimentary canal (Gastrointestinal or GI tract)
Group of organs that ingest, digest, absorb, defecate
Alimentary canal (Gastrointestinal or GI tract)
Include teeth, tongue, and several large digestive organs
Accessory digestive organs
Mucous membrane-lined cavity
Mouth (oral cavity)
Protect the anterior opening (regulate opening and closing of mouth)
Lips (Labia)
Form the lateral walls
Cheeks
Forms the anterior roof
Hard palate
Forms the posterior roof
Soft palate
Fleshy projection of the soft palate, prevents food from returning to the mouth after swallowing
Uvula
Space between lips externally and teeth and gums internally
Vestibule
Connects the lips and gums to the face; regulates lip movements
Labial frenulum
Area contained by the teeth
Oral cavity proper
Attached at the hyoid bone and styloid processes of the skull, and by the lingual frenulum to the floor of the mouth
Tongue
Located at the posterior end of oral cavity
Palatine
Located at the base of the tongue
Lingual
Chewing of food
Mastication
Part of the tongue that that allow for taste
Taste buds
___% of what we eat is what we smell
80%
Each taste bud has ____ taste cells and they are connected to the ________ receptors
40; taste
Initiates swallowing
Tongue
- Serves as a passageway for food, fluids, and air
Pharynx
Food passed from the mouth posteriorly and into the?
Oropharynx and Laryngopharynx
Posterior to oral cavity
Oropharynx
Below the oropharynx and continuous with the esophagus
Laryngopharynx
2 skeletal muscle layers in the pharynx that propels food into the esophagus?
The longitudinal outer layer and circular inner layer
Circular balls of food
Bolus
Alternating contractions of muscle layer that propel food create wavelike motions called?
Peristalsis
- About 10 inches long
- Runs from pharynx to stomach through the diaphragm
- Conducts food by peristalsis to the stomach
- Passageway for food only
Esophagus (gullet)
4 layer of tissue in the alimentary canal organs
- Mucosa
- Submucosa
- Muscularis externa
- Serosa
Innermost, membrane consisting of:
- Surface epithelium
- Small amount of connective tissue
- Scanty smooth muscle layer
- Lines the cavity
Mucosa
- Just beneath the mucosa
- Soft connective tissue with blood vessels, nerve endings, mucosa-associated lymphoid tissue, and lymphatic vessels
Submucosa
- Smooth muscle
- Stomach has middle oblique layer
- Inner circular and outer longitudinal layers for persitalsis motion
Muscularis externa
Outermost layer of the wall; contains fluid-producing cells
Serosa
Innermost layer that is continuous with the outermost layer
Visceral peritoneum
Mesenteries
Anchor organs in place, keeps S.I. contact
Outermost layer
Parietal peritoneum
- Group of nerves that control the alimentary canal structures
- Regulate mobility and secretory activity of the GI Tract organs
Alimentary canal nerve plexuses
Alimentary canal wall contains 2 intrinsic nerve plexuses that are part of autonomic N.S. called?
- Submucosal nerve plexus
- Myenteric nerve plexus
- C-shaped organ located on the left side of the abdominal cavity
- Can stretch and hold up to 4L of food when full
Stomach
Food enters at the _____________ from the esophagus to stomach
Cardioesophageal sphincter
Food empties at the _____________ (regulates propulsion) into the S.I.
Pyloric sphincter
Near the heart and surrounds the cardioesophageal sphincter; where the heart burn happens
Cardial (cardia)
Expanded portion lateral to the cardiac region
Fundus
- Midportion
- Greater curvature
- Lesser curvature
Body
Convex lateral surface; where great omentum is connected that attaches the stomach to transverse colon
Greater curvature
Convex medial surface; where lesser omentum is connected that attaches the stomach to liver
Lesser curvature
Funnel-shaped terminal end, where pyloric sphincter is found
Pylorus
Internal folds of the mucosa present when the stomach is empty
Rugae
Double layer of peritoneum; extends from the liver to the lesser curvature of stomach
Lesser omentum
- Another extension of peritoneum
- Covers the abdominal organs
- Fat insulates, cushions, and protects the abdominal organs
Greater omentum
Mucosa cells of the stomach produce __________ mucus
Bicarbonate-rich alkaline mucus
Hormone in the stomach needed for vitamin B12 absorption in S.I.
Intrinsic factors
Produce protein-digesting enzymes (pepsinogens)
Chief cells
Activated by histamine, produce HCl that activates enzymes (pepsinogen to pepsin)
Parietal cells
Produce thin acidic mucus
Mucous neck cells
Produce local hormones such as gastrin
Enteroendocrine cells
Most digestive activity occurs where?
Pyloric region
Food enters the S.I. through the pyloric sphincter as ________ which is like thick heavy cream
Chyme
- Body’s major digestive organ
- Longest portion of the alimentary tube
- Site of nutrient absorption of blood
- Muscular tube extending from the pyloric sphincter to the ileocecal valve
- Suspended from the posterior abdominal wall by the mesentery
Small intestine
Subdivision of the S.I.
- Duodenum
- Jejunum
- Ileum
First part, receives materials from stomach, liver, pancreas, gallbladder
Duodenum
Middle part, further digestion and absorption happen
Jejunum
Last part, joins the L.I. at the ileocecal valve
Ileum
Where does the chemical digestion begin? (except for mouth)
Small intestine
____ is formed by the liver and enters the duodenum via the _______
Bile; bile duct
Temporary storage site of bile
Gallbladder
Where the main pancreatic duct and bile ducts join
Hepatopancreatic ampulla
Hepatopancreatic ampulla is connected to the _________ which releases into duodenum
Duodenal papilla
- Fingerlike projection formed by the mucus
- House a capillary bed and lacteal
- Lots of villi in the first part of S.I.
Villi
Tiny projections of plasma membrane
Microvilli
For final digestion (under microvilli)
Brush border enzymes
Deeps fold of mucosa and submucosa, when food fills, form an internal “corkscrew slide” to increase surface area and force chyme to travel slowly through the S.I.
Circular folds (plicae circulares)
- Collection of lymphatic tissues
- Located in the submucosa
- Increase in the number at the end of the S.I.
Peyer’s patches
- Large in diameter, shorter in length
- Extends from ileocecal valve to anus
Large intestine
Subdivisions of large intestine
- Cecum
- Appendix
- Colon
- Rectum
- Anal canal
Saclike first part of L.I.
Cecum
Dangling piece of tissue that hangs from the cecum
Appendix
Accumulation of lymphoid tissue, sometimes becomes inflamed
Appendicitis
Travels up right side of abdomen and makes a turn at the right colic flexure
Ascending colon
Travels across the abdominal cavity and turns at the left colic flexure
Transverse colon
Travels down left side of the body
Descending colon
S-shaped region; enters the pelvis
Sigmoid colon
Where feces accumulate
Rectum
Where feces exits, ends at the anus
Anal canal
Opening of the L.I.
Anus
Formed by skeletal muscle, voluntary
External anal sphincter
Formed by smooth muscle, involuntary
Internal anal sphincter
Sphincters are normally closed except during?
Defecation
________ produce ________ to lubricate the passage of feces
Goblet cells; alkaline mucus
Muscularis externa layer reduced to 3 bands of muscle called?
Teniae coli
2 sets of teeth of humans
- Deciduous (baby/milk) teeth
- Permanent teeth
A baby has a full set of teeth by?
Age 2
First teeth to appear in babies are the?
Lower central incisors
Permanent teeth replace deciduous teeth between what ages?
6 and 12
How many teeth for a full set of permanent teeth?
32
Teeth are classified into?
- Incisors - cutting
- Canines - tearing or piercing
- Premolar - grinding
- Molars - grinding
Exposed part of tooth above the gingiva
Crown
Covers the crown, directly bears the force of chewing, hardest substance in the body, and is fairly brittle as heavily mineralized with calcium shots
Enamel
Found deep to enamel, forms bulk of tooth, surround pulp cavity
Dentin
Contains connective tissue, blood vessels, and nerve fibers
Pulp cavity
Where the pulp cavity extend into the root
Root canal
Covers outer surface of root, attaches tooth to periodontal memberane
Cement
Holds tooth in place in the bone jaw
Periodontal membrane
Connector between crown and root, region in contact with the gum
Neck
3 pairs of salivary glands
- Parotid glands
- Submandibular glands
- Sublingual glands
Found anterior to the ears, infections affect these glands
Parotid glands
Inflammation of parotid glands
Mumps
Empty saliva into the floor of mouth through small ducts
Submandibular glands
Empty saliva into the floor through small ducts
Sublingual glands
Mixture of mucous and serous fluids, helps to moisten and bind food together into bolus, dissolved food chemicals so they can be tasted
Saliva
Saliva contains:
- Salivary amylase
- Lysozymes and antibodies
Begins starch digestion
Salivary amylase
Inhibit bacteria
Lysozymes and antibodies
- Soft, pink triangular glad
- Found posterior to the parietal peritoneum
- Extends across the abdomen from spleen to duodenum
- Produces a wide spectrum of digestive system that break down food
- Secretes enzymes into the duodenum
Pancreas
Hormones produced by pancreas
Insulin and glucagon
- 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 by falciform ligament
Liver
Digestive role of liver
Produce bile
Bile leaves the liver through the ________ and enters the _______ through ________
Common hepatic duct; duodenum; bile duct
Yellow-green, watery solution that breaks down fat
Bile
Green sac found in a shallow fossa in the inferior surface of the liver
Gallbladder
Placing of food into the mouth
Ingestion
Movement of foods from one region of the digestive system to another
Propulsion
Alternating waves of contraction and relaxation that squeeze food along GI tract
Peristalsis
Movement of materials back and forth to foster mixing in S.I.
Segmentation
Food breakdown: Physically fragments food into smaller particles
Mechanical breakdown
Food breakdown: Enzymes chemically break down large molecules into their building blocks
Digestion
End products of digestion are absorbed in the blood or lymph
Absorption
Elimination of indigestible substances from the GI tract in the form of feces
Defecation
