Digestive System Flashcards
provides the nutrients cells need for maintenance and growth
digestive system
muscular tube in the digestive system lined by a mucous epithelium also known as the gastrointestinal tract
digestive tract
name the accessory organs of the digestive system
- salivary glands
- liver
- gallbladder
- pancreas
the longest segment of the digestive tract
small intestine
a double sheet of peritoneal membrane that stabilizes the positions of the attached organs and prevent the intestines from becoming entangled during digestive movements or sudden changes in body position
mesentery
name the 2 layers of the mesentery
- mesothelium
- areolar tissue
name the major layers of the digestive tract
- mucosa
- submucosa
- muscularis externa
- serosa
inner lining of the digestive tract that is moisten by glandular secretions and a lamina propia of areolar tissue
mucosa
a layer of dense irregular connective tissue that surrounds the mucosa and contains exocrine glands that secrete buffers and enzymes into the lumen of the digestive tract
submucosa
smooth muscle cells that contains two layers that play an essential role in mechanical processing and in the movement of materials along the digestive tract
muscularis externa
name the two layers of the muscularis externa
- inner circular layer
- outer longitudinal layer
a layer of visceral peritoneum that covers the muscularis externa
serosa
a part of the serosa that firmly attaches the digestive tract to adjacent structures
adventitia
permanent transvers folds in the intestinal lining
plicae circulares
name the 3 components of the mucosa
- villi
- lamina propia
- muscularis mucosae
small mucosal projections that stick into the lumen of the small intestine, and also increases the surface are available for absorption
villi
consists of a layer of areolar tissue
lamina propria
consists of two concentric layers of smooth muscle whose contractions alter the shape of the lumen and move the plicae and villi
muscularis mucosae
name the two layers of the muscularis mucosae
- circular muscle layer
- longitudinal muscle layer
the inner layer of the muscularis mucosae that encircles the lumen
circular muscle layer
the outer layer of the muscularis mucosae that contains muscle cells oriented parallel to the long axis of the tract
longitudinal muscle layer
a nerve network that contains sensory neurons, parasympathetic ganglionic neurons, and sympathetic postganglionic fibers that innervate the mucosa and submucosa
submucosal plexus
a network of parasympathetic neurons, interneurons, and sympathetic postganglionic fibers that lies between the circular and longitudinal muscle layers
myenteric plexus
regulates movement of materials along internal passageways of the digestive tract and mechanical processing, lacks myofibrils and sacomeres, does not contain striations (nonstriated muscle)
smooth muscle
name the two types of smooth muscle in the digestive tract
- multi-unit smooth muscle
- visceral smooth muscle
increases muscle tone and activity in the digestive system
parasympathetic nerves
promotes muscular inhibition and relaxation in the digestive system; inhibits digestion
sympathetic nerves
mechanical processing; cycles of contraction that churn and fragment the bolus, mixing the contents with intestinal secretions
segmentation
contractions that propel materials from one portion of the digestive tract to another; moving materials along the digestive tract; a wave of contraction in the circular muscles that forces the bolus forward
peristalsis
name the 3 major mechanisms that regulate and control the digestive activities
- local factors
- neural control mechanisms
- hormonal control mechanisms
a reflex that is responsible for the wave of peristalsis moving along the intestine and that involves contraction of the digestive tube above and relaxation below the place where it is stimulated by an accumulated mass of food
myenteric reflex
stimuli for digestive activities, such as changes in pH or distortion of the intestinal lumen
local factors
involves myenteric reflexes
neural mechanisms
involves neuroendocrine cells
hormonal mechanisms
endocrine cells in the epithelium of the digestive tract
enteroendocrine cells
contains the tongue, salivary glands, and teeth, and receives secretions of the salivary glands; lined by the oral mucosa
oral cavity
what are the two movements of the digestive system
- mixing food
- propelling food forward through the system
physically grinding and mixing w saliva
mastication
layer of the muscularis externa that squeezes closed like a sphincter
inner circular fibers
layer of muscularis externa that shortens
outer longitudinal fibers
name the 2 functions of the digestive system
- digestion
- absorption
transport of digested nutrients into blood stream
absorption
breaking down of food
digestion
palate used for mastication
hard palate
palate used for swallowing
soft palate
covers the nasal cavity during swallowing
uvula
name the 4 different types of teeth
- incisors
- cuspids
- bicuspids
- molars
hardest structures in the body; not considered bones because they have two proteins not found in bones and their structure is different
teeth
what two things play a key role in swallowing
- pharynx
- esophagus
an anatomical space that serves as a common passageway for solid food, liquids, and air
pharynx
a hollow muscular tube that conveys solid food and liquids to the stomach; the structure connecting the pharynx to the stomach
esophagus
connective tissue outside of the muscularis externa that anchors the esophagus to the posterior body wall
adventitia
a complex process that can be initiated voluntarily but proceeds automatically once it begins; swallowing
deglutition
name the 3 parts of the pharynx
- nasopharynx
- oropharynx
- laryngopharynx
part of pharynx that connects the nasal cavity to back of mouth
nasopharynx
part of pharynx that located at the back of the mouth
oropharynx
part of pharynx that is below the mouth to the larynx
laryngopharynx
name the 3 stages of deglutition
- buccal phase
- pharyngeal phase
- esophageal phase
voluntary phase of deglutition where food is formed into a bolus and the tongue pushes the bolus to the back of the mouth
buccal phase
the bolus contacts the palatal arches and moves into the esophagus
pharyngeal phase
swallowing begins as pharyngeal muscles contract and the bolus is moved toward the stomach via peristaltic
esophageal phase
prevents the backflow of materials from the stomach into the esophagus; closes opening to stomach
lower esophageal sphincter
what 2 ways can the serous membrane be divided
- visceral peritoneum
- parietal peritoneum
a ventral body cavity lined by a serous membrane called the peritoneum
peritoneal cavity
serosa that covers organs within the peritoneal cavity
visceral peritoneum
lines the inner surfaces of the body wall
parietal peritoneum
a muscular, expandable, J-shaped organ with three layers in the muscularis externa
stomach
name the 4 regions of the stomach
- cardia
- fundus
- body
- pylorus
secrete most of the acid and enzymes involved in gastric digestion and located in the fundus and body
gastric gland
secrete intrinsic factor and hydrochloric acid
parietal cells
a glycoprotein that facilitates the absorption of vitaminB12 across the intestinal lining; required for absorption of B12 vitamins
intrinsic factor
secrete pepsinogen
chief cells
a sudden influx of bicarbonate ions into the bloodstream from active parietal cells; it causes a temporary increase in blood pH
alkaline tide
protects epithelial cells against the acid and enzymes in the gastric lumen
alkaline mucous layer
specialized for the absorption of nutrients
intestinal tract
capillaries that carry absorbed nutrients to the hepatic portal circulation for delivery to the liver, which adjusts the nutrient concentrations in blood before the blood reaches the general systemic circulation
lamina propria
lymphatic capillaries in the intestinal villi that transport absorbed fatty acids that cannot enter blood capillaries
lacteal
plays the key role in the digestion and absorption of nutrients
small intestines
name the 3 regions of the small intestines
- duodenum
- jejunum
- ileum
region of small intestine that receives chime from the stomach and neutralize its acids to avoid damaging the absorptive surfaces of the remaining regions of the small intestines
duodenum
begins to break down proteins
pepsin
acid that converts pepsinogen to pepsin
hydrochloric acid
breaks down lipids
lipase
name the 5 hormones that are involved in the regulation of digestive activities
- gastrin
- secretin
- gastric inhibitory peptide (GIP)
- cholecystokinin (CCK)
- vasoactive intestinal peptide (VIP)
secreted by G cells in the pyloric antrum and enteroendocrine cells in the duodenum. promotes increased stomach motility and stimulating the production of gastric acids and enzymes
gastrin
released when chime arrives in the duodenum; reduces gastric motility and secretory rates. primary effect is an increase in the secretion of bile (by the liver) and buffers ( by the pancreas) which in turn act to increase the pH of the chyme
secretin
secreted when fats and carbohydrates enter the small intestine; stimulates duodenal gland activity, stimulates lipid synthesis in adipose tissue, and increasing glucose use by skeletal muscles
gastric inhibitory peptide (GIP)
secreted when chime arrives in the duodenum. it increases the secretion of pancreatic enzymes and push pancreatic secretions and bile into the duodenum. inhibits gastric activity, and it appears to have CNS effect that reduce the sensation of hunger
cholecystokinin (CCK)
stimulates the secretion of intestinal glands, dilates regional capillaries, and inhibits acid production in the stomach. it provides an efficient mechanism for removing absorbed nutrients
vasoactive intestinal peptide (VIP)
name the 3 phases of secretion
- cephalic phase
- gastric phase
- intestinal phase
begins when you see, smell, taste, or think of food. directed by the CNS and triggers the parasympathetic reflexes; prepares the stomach to receive food
cephalic phase
begins with the arrival of food in the stomach and builds on the stimulation provided during the cephalic phase. during this period, gastrin stimulates contractions in the muscularis externa of the stomach and intestinal tract
gastric phase
begins when chime first enters the small intestine, it controls the rate of gastric emptying to ensure that the secretory, digestive, and absorptive functions of the small intestine can proceed with reasonable efficiency; controls the rate of gastric emptying
intestinal phase
inhibits both gastrin production and gastric contractions and stimulates the contraction of the pyloric sphincter, which prevents further discharge of chyme
enterogastric reflex
name the two central reflexes triggered by stimulation of the stretch receptors in the stomach wall
- gastroenteric reflex
- gastroileal reflex
stimulates motility and secretion along the entire small intestine
gastroenteric reflex
triggers the opening of the ileocecal valve, allowing materials to pass from the small intestine into the large intestine
gastroileal reflex
functions include the reabsorption of water and the compaction of the intestinal contents into feces, the absorption of important vitamins liberated by bacterial action, and the storage of fecal material prior to defecation. consist of the cecum, the colon, and the rectum
large intestine
name the 4 regions of the colon
- ascending colon
- descending colon
- sigmoid colon
- transverse colon
the exit of the anal canal
anus
lubricate and moisten the mouth and initiate the digestion of complex carbohydrates; secretes saliva
salivary glands
a mixture of glandular secretions in the mouth; a mixture of serous and mucous
saliva
name the 3 pairs of salivary glands
- sublingual salivary glands
- submandibular salivary glands
- parotid salivary glands
salivary gland that produce secretion that acts as a buffer and lubricant
sublingual salivary glands
salivary gland that secretes a mixture of buffers, mucins, and a salivary amylase. transport antibodies into the saliva, to provide additional protection against pathogens in food
submandibular salivary glands
an enzyme that break down complex starches (complex carbohydrates)
salivary amylase
drains the secretions of the parotid salivary gland and empties them into the vestibule at the level of the second upper molar
parotid duct
salivary gland that produce a secretion containing large amounts of salivary amylase
parotid salivary glands
secrete mucins, water, and buffers
mucous cells
secrete salivary amylase and lysozyme; transport antibodies from the interstitial fluid into the saliva
serous cells
the largest internal organ and where bile is produced
liver
produces bile which emulsifies lipids into smaller droplets
lipid metabolism
deaminating amino acids, forming urea, synthesizing plasma proteins and clotting factors
protein metabolism
stores bile produced by the liver and releases it into the small intestine
gallbladder
name the 3 regions of the gallbladder
- fundus
- body
- neck
provides several digestive enzymes necessary for the breakdown of starches, lipids, nucleic acids, and proteins
pancreas
begins carbohydrate digestion by breaking down starch and glycogen to disaccharides
salivary amylase
begins protein digestion
pepsin
begins butterfat digestion
gastric lipase
breaks down starch and glycogen into disaccharides
pancreatic amylase
breaks down fats into fatty acids and glycerol
pancreatic lipase
breaks down peptides into amino acids
carboxypeptidase
breaks down nucleic acids into nucleotides
nucleases
breaks down peptides into amino acids
peptidase
breaks down fats into fatty acids and glycerol
intestinal lipase
shortens trypsinogen into trypsin
enterokinase
