Quiz 2 - Digestive system Flashcards
Quiz Thursday
Mechanical breakdown of foods
2 types:
* Mechanical: Breaks down large pieces of food into smaller ones, but doesnt change chemical composition
* Chemical: uses enzymes to breakdown food particles by changing them into simpler chemicals
Digestion
Organs of system that carry out mechanical & chemical digestion, as well as ingestion, propulsion, absorption, & defication
Consists of alimentary canal & accessory organs
Digestive system
1 of 2 portions of the digestive system that consists of organs that extens from mouth to anus
* Food passageway
Mouth, pharynx, esophagus, stomach, small/large intestine, & anal canal
Alimentary Canal
1 or 2 portions of the digestive system that consists of organs that empty serections into alimentary canal
* Food does not pass through
Salivary glands, liver, gallbladder, & pancreas
Accessory Organs
List the 4 layers of the walls that make up the alimentary canal in order from inner most to outer most:
- Mucosa
- Submucosa
- Muscularis (external)
- Serosa
Inner most layer of the alimentary canal that directly surrounds the lumen (passageway)
* Made up of Epithelium, connective tissue, smooth muscle
Folded in some areas to increase surface area
Absorbs dietary nutrients, secretes mucous & enzymes, & provides protection
Mucosa
Layer of the alimentary canal made of connective tissue that contain blood & lymphatic vessels, nerves, & glands
Nourishes cells, transports absorbed food molecules
Submucosa
Muscle tissue that contain circular & lymphatic vessels, nerves, & glands
Made up of Smooth muscle cells in circular and longitudinal groups
Moves tube & food materials
Muscularis (external)
Outer layer of serous fluid that eliminates friction
Made up of Epithelium, connective tissue
Visceral peritoneum of organs w/in
Function: Protection, lubrication
Serosa
Describe the 2 types of movements of the Alimentary Canal Wall listed below:
Mixing movements
Propelling movements
Mixing movements: Muscles contract rhythmically
* Moves materials in multiple directions
* Ex: Segmentation in small intestine, churning in stomach
Propelling movements: Moves material in one direction
* Peristalsis: Ring of contraction progress down tube; proper food particles down tract in wavelike motion
Fill in the blank
Branches of (x) & (x) division of autonomic nervous system extensively innervate the alimentary canal
A) Sympathetic & parasympathetic
B) Nerves & arteries
C) Submucosal plexus & myenteric plexus
A) Sympathetic & parasympathetic
Branches of Sympathetic & parasympathetic division of autonomic nervous system extensively innervate the alimentary canal
What is the difference between submucosal plexus & myenteric plexus?
Submucosal plexus: Controls secretions
Myenteric plexus: Controls GI motility
What 2 impulses have autonomic control over the digestive system?
Parasympathetic Impulses: Increase activity in digestive system
Sympathetic Impulses: Inhibit digestive ations (secretion & motility)
Secrete chemical messengers (hormones) to regulate GI organs & processes
Enteroendocrine cells
First part of the alimentary canal that ingests food
* Mastication: Mechanical breakdown of food mixed w/ saliva
Functions as organ of organ of speech & sensory receptory
Surrounded by lips, cheeks, tongue, & palate
* Includes oral cavity & vesibules
Mouth
Form lateral walls of the mouth
Contain muscles for facial expression & chewing
Have inner lining of stratified squamous epithelium (moist)
Cheeks
Highly mobile structure that surrounds mouth opening
Sensory receptors judge of temp & texture of food
Boundry between skin & mucous membrane inside mouth
Lips
Thick, muscular organ that occupies floor of mouth & nearly fills oral cavity when mouth is closed
Lingual Frenulum: Connects to floor of mouth
Papillae: Projections that move food, & contain taste buds
Lingual Tonsils: Lymphatic tissue masses on root of tongue
Tongue
Consists of an anterior portion (hard palate) & posterior portion (soft palate)
Hard (bony) Palate: Consits of palatine process of maxillae & palatine bone
Soft Palate: Consists of muscular arch that ends in uvula
Palate
Describe the tonsils listed below:
Palatine Tonsilis
Pharyngeal tonsils (Adenoids)
Palatine Tonsilis: Lymphatic masses on side on tongue
Pharyngeal tonsils (Adenoids): Masses on lympahtic tissue in postieror wall of pharyns
Breaks down food - Mechanical digestion
* Chewing mixes food w/ enzymes
* Hardest part of the body that is not part of the skeletal system
20 primary (Deciduous), & 32 secondary (adult)
Types:
* Central incisors, lateral incisors
* Canines (cuspids), premoloar (bicuspids)
* First, second, & third molars
Teeth
Describe the following in regads to teeth:
Incisors
Canines
Molars / Premolars
Enamel
Dentin
Periodontal ligament
Incisors: Biting
Canines: Grasping / Tearing
Molars & premolars: Grinding
Enamel: Covers crown
Dentin: Makes up most teeth & surround pulp cavity
Periodontal ligament: Holds root in place along w/ cementum
Secrete saliva
* Dissolve food
Contains enzymes (chemiac digestion of carbs) & bicarb ions (Keep pH favorable from enzyme activity & protect teeth from acidic foods)
3 major types:
* Parotid glands
* Submandibular glands
* Sublingual glands
Salivary Glands
What are the 3 major salivary glands?
Parotid glands: Large gland that secretes serous saliva w/ amylase
Submandibular glands: Floor of mouth; Serous + mucous
Sublingual glands: Under tongue; Mainly mucous
Extends from nasal cavity to esophagus
Cavity posterior to mouth
Pharynx
Posterior to nasal cavity
Air passageway
Contain opening to auditory tubes
Nasopharynx
Posterior to oral cavity
Air & food passageway
Oropharynx
Posterior to larynx
Passageway to esophagus
Laryngopharynx
Tubular organ that extends from pharynx to stomach
* Muscular food passageway (25cm)
* Penetrates diaphram through esophageal hiatus
Contains mucous glands in submucosa
* Moistens & lubricates lining of inner walls w/ mucus
Esophagus
Fill in the blank
(x) sphincter regulates food passage into stomach & closes to prevent regurgitation of food
A) Upper esophageal
B) Lower esophageal (cardiac)
C) Ileocecal
B) Lower esophageal (cardiac)
Lower esophageal (cardiac) sphincter regulates food passage into stomach & closes to prevent regurgitation of food
J-shaped, pouch like organ located inferior to diaphram, in upper L portion of abd. cavity (25-30cm)
* Contains layers of smooth muscle
Recieves food from esophagus
Mixes food w/ gastric juice
Initiates protein digestion
Has limited absorption
Moves food into small intestine
Stomach
Describe the parts of the stomach listed below:
Cardia
Fundus
Body
Pylorus
Pyloric sphincter
Cardia: Contains lower esophageal sphincter
* Region near esophagus opening
Fundus: Rounded area that arises above cardia
Body: Lies between fundus & pylorus (main portion)
Pylorus: Funnel shaped pyloric antrum narrows to become pyloric canals
* Distal portion, closest to small intestine
Pyloric sphincter: Circular smooth muscle
* Controls gastric emptying
Desribe the following terms below related to gastric secretions:
Mucus
Pepsinogen
Pepsin
Gastric Lipase
Hydrochloric acid
Chemical Messenger
Mucus: Provides lubrication & protects the stomach lining
* Secreted by mucous neck cells
Pepsinogen: Inactive form of pepsin
* Secreted by chief cells
Pepsin: Active enzyme that breaks down protiens into polypeptides
* Form from pepsinogen in presence of HCL
Gastric Lipase: Fat splitting enzymes, found in small quantities
* Action inhibits low pH
Hydrochloric acid: Produced by parietal cells
* Required from absorption of vitamin B12
Chemical Messenger: substances (hormones & local messengers) that regulate digestive process
* Secreted by enterendocrine cells
What is the differecnce between Neural regulation & Hormnal regulation?
Neural regulation:
* Sympathetic impulses decrease gastric activity
* Parasympathetic impulses increase gastric activity; promote release of histamine, which stimulates gastric secretion
Hormonal regulation:
* Somatostatin: Inhibits HCl secretion
* Gastrin: Increases gastric juice secretion
* Cholecystokinin (CCK): Released by small intestine cell when proteins and fat enter the small intestine; decreases gastric motility
Sight, taste, smell, or thought of food triggers parasympathetic reflexes
Gastric juice is secreted in response
Cephalic Phase
Food in stomach chemically and mechanically stimulates release of gastrin (stimulates secretion of gastric juice)
Reflex responses also stimulate gastric juice secretion
Gastric phase
Food enters the small intestine stimulating intestinal cells to release intestinal gastrin
* Promotes the secretion of gastric juice from the stomach wall
Primarily inhibits gastric juice secretion by sympathetic reflex and the hormone cholecystokinin responses
Intestinal phase
What 4 substances are absorbed by the stomach?
Some water
Certain salts
Certain lipid-soluble drugs
Some alcohol
What is the term for mixing of food in the stomach with gastric juice produces a semifluid paste ?
Chyme
Which sphincter prevents backflow of chyme into esophagus?
A) Lower esophageal sphincter
B) Upper esophageal sphincter
C) Lower Ileocecal sphincter
D) Upper Ileocecal sphincter
A) Lower esophageal sphincter
Forces food out through mouth
Causes include:
* Certain drugs
* Toxins from food
* Overstretching of stomach
* Body motion changes
* Motion sickness associated with inner ears (Vertigo)
Controlled by center in medulla oblongata
Motor response involves deep breath, raising of soft palate, closing of nasal cavity and glottis, relaxation of lower esophageal sphincter, contraction of diaphragm and abdominal wall muscles
Vomiting
Endocrine gland, secreting insulin and glucagon to regulate blood glucose
* Exocrine gland of the digestive system, secreting digestive fluid called pancreatic juice
Pancreas
What are the structures of the pancreas?
Pancreatic acinar cells make up most of pancreas, and release pancreatic juice into tiny ducts which lead to the pancreatic duct
Pancreatic duct (along with the common bile duct from the liver and gall bladder) empties into the duodenum of the small intestine
Pancreatic duct and common bile duct join at dilated tube (hepatopancreatic ampulla - of Vater)
Hepatopancreatic sphincter (of Oddi) surrounds ampulla; controls movement of bile and pancreatic juice into duodenum
Describe the Components of pancreatic juice listed below:
Pancreatic amylase
Pancreatic lipase
Trypsin
Chymotrypsin
Carboxypeptidase
Nucleases
Pancreatic amylase: Splits starch and glycogen into disaccharides
Pancreatic lipase: Breaks down triglycerides
Trypsin: Digests proteins & releases as inactive trypsinogen (activated by enterokinase in small intestine)
Chymotrypsin: Digest proteins & releases as inactive enzyme* (activated by trypsin)*
Carboxypeptidase: Digests proteins & releases as inactive enzyme (activated by trypsin)
Nucleases: Digests nucleic acids
Bicarbonate ions
* Make pancreatic juice alkaline; buffer stomach acid
What 2 Hormones that help regulate the release of pancreatic juice?
Secretin:
* Stimulates pancreas to release pancreatic juice high in bicarbonate ions
CCK:
* Stimulates pancreas to release pancreatic juice high in enzymes
Largest internal organ located in the upper-right abdominal quadrant beneath the diaphragm
Reddish-brown organ
Hepatic portal vein brings absorbed nutrients to hepatic sinusoids
Hepatic artery brings oxygen-rich blood, which mixes with oxygen-poor blood from portal vein
Liver
What are some functions of the liver?
Synthesizes lipoproteins, phospholipids, and cholesterol
Synthesizes plasma proteins
Stores glycogen, iron, and vitamins A, D, and B12
Removes toxins, such as alcohol and certain drugs from the blood
Oxidizes fatty acids
Acts as blood reservoir
Role in digestion is to secrete bile
Breaks down glycogen into glucose
Yellowish-green liquid that hepatic cells continuously secrete
Components include:
* Water
* Salts
* Pigments
* Cholesterol
* Electrolytes
Released under control of hormone cholecystokinin
* Stimulates contraction of gallbladder
Bile
Yellowing of skin, eye sclerae, mucous membranes
Caused by blockage of bile ducts:
* Cirrhosis or hepatitis
* Rapid red blood cell destruction
Jaundice
Pear-shaped sac that stores and concentrates bile
Cystic duct (entry/exit duct) merges with common hepatic duct to form common bile duct
Releases bile into duodenum of small intestine
* Hepatopancreatic ampulla
Hepatopancreatic sphincter regulates release of bile into the duodenum
Gallbladder
What are some causes form gallstones?
Excess bile concentratio
Excess cholesterol secretion by liver
Inflammation of the gallbladder
Bile salts help absorb what fat-soluable vitamins?
vitamins A, D, E, and K
Tubular organ that extends from the pyloric sphincter to the beginning of the large intestine
Receives chyme from the stomach, and liver and pancreatic secretions
Absorbs products of digestion
* Completes digestion of the nutrients in chyme
* Transports the remaining residue to the large intestine
3 parts:
* Duodenum
* Jejunum
* Ileum
Small intestine
Describe the 3 parts or the small intestine:
Duodenum
Jejunum
Ileum
Duodenum: Shortest and most fixed portion of small intestine
Jejunum: Middle portion, thicker and more active than ileum
Ileum: Distal portion; contains Peyer’s patches (lymph nodules)
What are the 5 secretions of the small intestine?
Mucus
Watery fluid
Enzymes:
* Peptidases: Break down peptides into amino acids
* Sucrase, maltase, lactase: Break down disaccharides into monosaccharides
* Lipase: Breaks down fats into fatty acids and glycerol
Chemical messengers: Secretin and cholecystokinin
* Secreted by enteroendocrine cells scattered throughout mucosa of duodenum
Antimicrobial substances: Defend against certain bacteria
Increase the surface area for absorption
* Small intestine is most important absorbing organ of alimentary canal
Little absorbable material reaches the organ’s distal end
Villia
The small intestine carries which 2 movements?
Peristalsis: Wave-like pushing movements that moves chyme into the small intestine
Segmentation: Ring-like contractions that move chyme back and forth (mixing movement)
* Places chyme in contact with digestive enzymes in brush border and aids in absorption
Joins ileum of small intestine to cecum of large intestine, and helps regulate flow of chyme
Ileocecal sphincter
At distal end, opens to outside of body through the anus (1.5 m)
Absorbs some water and electrolytes
* Reabsorbs and recycles water and digestive secretions
Forms and stores feces
4 Major parts:
* Cecum
* Colon
* Rectum
* Anal canal
Large Intestines
Describe the 4 Major parts of the large instesine listed below:
Cecum
Colon
Rectum
Anal canal
Cecum: Pouch, forms beginning of large intestine
* Appendix is attached to cecum; lymph nodules in appendix function in the immune response
Colon: Ascending, transverse, descending, and sigmoid portions
* Contain hepatic (right colic) and splenic (left colic) flexures
Rectum: Extends from sigmoid colon to anal canal
* Lies next to sacrum
Anal canal: Last 2.5 to 4 cm of large intestine
* Opens to outside as anus
* Internal and external anal sphincters guard anus
What are some functions of the large intestine?
Has little or no digestive function
Contains tubular glands holding goblet cells
Forms feces, and carries out defecation
Secrete mucus (only significant secretion)
Houses intestinal flora
* Bacteria that breaks down contents (cellulose), and produce vitamins K, B12, thiamine
Absorbs water (about 90% of water that enters it) and electrolytes
What are feces made up of?
Water (75%)
Electrolytes
Mucus
Bacteria
Bile pigments (provide the color after bacterial alteration)
What 5 bacterial chemicals cause the odor of feces?
Phenol
Hydrogen sulfide
Indole
Skatole
Ammonia
What are some life span changes involving the digestive system?
Tooth enamel thins; teeth may become sensitive; Teeth may loosen, break, or fall out
Slowing peristalsis may lead to heartburn; Gastric secretion slows
Constipation may become more frequent; Nutrient absorption decreases (fat-soluble vitamins)
Incidence of lactose intolerance increases
