Digestive system Flashcards
The mechanical and chemical breakdown of foods into forms that cell membranes can absorb
digestion
breaks down large pieces of food into smaller ones, but does not change chemical composition
Mechanical digestion
uses enzymes to break down food particles, by changing them into simpler chemicals
Chemical digestion
Organs of the digestive system carry out mechanical and chemical digestion, as well as ingestion, propulsion, absorption, and defecation
Digestive System
digestive system consists
alimentary canal and accessory organs
What has the Mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anal canal, food passage way
Alimentary canal
Food does not pass through them, Salivary glands, liver, gallbladder, pancreas, empty secretions into alimentary canal
Accessory organs
Innermost layer, mucous membrane, Absorbs dietary nutrients, secretes mucus and enzymes
Mucosa
Connective tissue layer, Nourishes cells, transports absorbed food molecules
Submucosa
Muscle tissue (smooth muscle); contains circular and longitudinal layers, Moves tube and food materials
Muscularis (externa)
Outermost layer; serous fluid eliminates friction, Visceral peritoneum of organs within abdominal cavity
Serosa
Mixing movements and propelling movements
movements of the alimentary canal
Muscle in small sections contracts rhythmically, Does not move materials in one direction
Mixing movements
Moves materials in one direction
Propelling movements
Ring of contraction progresses down tube; propels food particles down the tract in wavelike motion (propelling movements)
Peristalsis
Mechanical breakdown of solid particles, mixes them with saliva
Mastication
Contain muscles for facial expression and chewing, Have an inner lining of stratified squamous epithelium (moist)
Cheeks
Highly mobile structures that surround the mouth opening, Sensory receptors judge temperature and texture of food, Boundary between skin and mucous membrane inside mouth
Lips
Thick, muscular organ that occupies the floor of the mouth, and nearly fills the oral cavity when the mouth is closed
Tongue
What are the three parts of the tongue? Describe them
-Lingual frenulum: Connects tongue to floor of mouth
*Papillae: Projections that move food, contain taste buds
*Lingual tonsils: Lymphatic tissue masses on root of tongue
roof of the oral cavity, anterior portion, the hard palate, and a posterior portion, the soft palate
Palate
Lymphatic masses on sides of tongue
Palatine tonsils
Masses of lymphatic tissue in posterior wall of pharynx
Pharyngeal tonsils (adenoids)
Hardest structures in the body
20 primary (deciduous)
32 secondary (permanent)
Teeth
Produce a watery fluid, containing a digestive enzyme called salivary amylase
Serous cells
Secrete mucus
Mucus binds food particles and lubricates food while swallowing
Mucous cells
Cavity posterior to the mouth
Extends from nasal cavity to esophagus
Pharynx
Posterior to nasal cavity; air passage; contain openings to auditory tubes
Nasopharynx
Posterior to oral cavity; air and food passage
Oropharynx
Posterior to larynx; passageway to esophagus
Laryngopharynx
Tubular organ that extends from the pharynx to the stomach
Esophagus
Receives food from the esophagus
*Mixes food with gastric juice
*Initiates protein digestion
*Has limited absorption
*Moves food into small intestine
Stomach
Region near opening to esophagus
Contains lower esophageal sphincter (Stomach)
Cardia
Rounded area that rises above cardia
Temporary food storage, which sometimes contains swallowed air (Stomach)
Fundus
Main portion
Lies between fundus and pylorus (Stomach)
Body
Distal portion, closest to small intestine
Funnel-shaped pyloric antrum narrows to become pyloric canal
Pyloric sphincter: Circular smooth muscle, controls gastric emptying (Stomach)
Pylorus
Inactive form of pepsin; secreted by chief cells (Gastric secretion)
Pepsinogen
(Gastric secretion) Active enzyme that beaks down proteins into polypeptides; forms from pepsinogen in presence of hydrochloric acid
Pepsin
(Gastric secretion) Fat-splitting enzyme, found in small quantities; action inhibited by low pH
Gastric lipase
(Gastric secretion) Produced by parietal cells; converts pepsinogen into pepsin
Hydrochloric acid
(Gastric secretion) Secreted by mucous cells; provides lubrication and protects stomach lining
Mucus
(Gastric secretion) Produced by parietal cells; required for absorption of vitamin B12
Intrinsic factor
Sympathetic impulses decrease gastric activity
Parasympathetic impulses increase gastric activity; promote release of histamine, which stimulates gastric secretion
Neural regulation
What makes up Hormonal regulation describe it
Somatostatin: Inhibits hydrochloric acid secretion
Gastrin: Increases gastric juice secretion
Cholecystokinin (CCK): Released by small intestine cells when proteins and fat enter the small intestine; decreases gastric motility
What causes vomiting?
Result of reflex that empties stomach in reverse direction
Causes include certain drugs, toxins from food, overstretching of stomach, body motion changes, motion sickness associated with inner ears, vomiting center in medulla oblongata
Contains enzymes that digest carbohydrates, fats, proteins, and nucleic acids
Pancreatic juice
(component of pancreatic juice) Splits starch and glycogen into disaccharides
Pancreatic amylase
(component of pancreatic juice) Breaks down triglycerides
Pancreatic lipase
(component of pancreatic juice) Digests proteins; released as inactive trypsinogen, which is activated by enterokinase in small intestine
Trypsin
(component of pancreatic juice) Digest proteins; released as inactive, activated by trypsin
Chymotrypsin
(component of pancreatic juice) Digests proteins; released as inactive, activated by trypsin
Carboxypeptidase
(component of pancreatic juice) Digest nucleic acids
Nucleases
(component of pancreatic juice) Make pancreatic juice alkaline; buffer stomach acid
Bicarbonate ions
Largest internal organ
Well-supplied with blood vessels
Liver
Lobes of the liver
-Right lobe: Largest lobe
*Left lobe: Smaller than right lobe
*Quadrate lobe: Minor lobe, near gallbladder
*Caudate lobe: Minor lobe, near inferior vena cava
What is the major liver function?
Producing glycogen to glucose
What is a cause of pancreatic cancer?
Gallostones
What are components of bile?
Water, bile pigments, and bile salts
*Produced from cholesterol
*Emulsify fats
*Only bile component that have a digestive function (act as fat emulsifying agents)
Bile salts
Bilirubin and biliverdin, derived from hemoglobin breakdown
*Cholesterol
*Electrolytes
Bile pigment
What is the name that causes these symptoms?
*Yellowing of skin, eye sclerae, mucous membranes
*Caused by blockage of bile ducts, diseases, such as cirrhosis or hepatitis, or rapid red blood cell destruction
Jaundice
Found on the inferior surface of the liver
Has the hepatopancreatic sphincter
Gallbladder
Excess bile concentration, too much cholesterol secretion by liver, or inflammation of the gallbladder
Gallostones
What are some functions of bile salt?
Help absorb fat-soluble vitamins A, D, E, and K
Break up of large fat globules
Aid digestive enzymes through emulsification
Fills most of the abdominal cavity
Completes the digestion of nutrients in chime
Absorbs the products of digestion
Small intestine
What enzymes are in the membrane of the microvilli?
Peptidases: Break down peptides into amino acids
Sucrase, maltase, lactase: Break down disaccharides into monosaccharides
Lipase: Breaks down fats into fatty acids and glycerol
Wha absorptions happen in the small intestines?
*Emulsified by bile salts
*Digested mainly by enzymes from pancreas and small intestine
*Digested into glycerol and fatty acids
*Fatty acids and glycerol are absorbed by a process involving several steps; absorbed into blood or lymphatic capillaries (lacteals)
Loose complexes of fatty acids and bile salts, from which fatty acids can migrate to microvilli and be absorbed
Micelles
New triglyceride clusters are encased in protein, form what?
chylomicrons
At distal end, opens to outside of body through the anus
*Absorbs some water and electrolytes
Stores and forms feces
Little to none digestive function
Large intestine
What are the parts of the large intestine? Describe them
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
*Contains 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 does the large intestinal wall not have?
Does not have villi and plicae circulares
Muscle bands create pouches called what in the large intestine wall?
Haustra
Longitudinal muscle is organized into 3 bands, runs down entire length of the colon
taeniae coli
What is intestinal gas?
Mixture of nitrogen, oxygen, methane, carbon dioxide, hydrogen, ammonia, and hydrogen sulfide (causes unpleasant odor)
What are two movements of the large intestine?
*Mass movements: Peristaltic waves, 2 to 3 times/day, which usually follow meals
*Defecation reflex: Eliminates feces from body
*Involves holding deep breath, contracting abdominal muscles
*Feces move into rectum
*Peristaltic waves occur in descending colon
*Relaxes internal anal sphincter, and then external anal sphincter
What causes the pungent order of feces?
Phenol
Hydrogen sulfide
Indole
Skatole
Ammonia
What is feces composed of?
Materials not digested or absorbed
mucus
Water 75%
Electrolytes
Bacteria
Bile pigments (color in poop)
