Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
76 Cards in this Set
- Front
- Back
|
How does smooth muscle contract?
|
Thin filaments attach to plasma membrane
|
|
|
How is contraction regulated?
|
Ca binds to calmodulin, activating MLCK, P myosin, and now the myosin light chain can interact with actin
|
|
|
Sources of Ca in smooth muscle?
|
SR, extra cellular Ca
|
|
|
How is smooth muscle contraction controled?
|
regulation of Ca availability
|
|
|
How is force maintained as intracellualar ca decreases?
|
Because MLCK is still phosphoralated
|
|
|
How do you relax smooth muscle?
|
de-phosphorlate MLC
|
|
|
T/F Smooth muscle has pacemaker capabilities
|
T -- works through AP transmited to neighboring cells through gap junctions
|
|
|
What is sm innervated by?
|
postganglionic autonomic n
|
|
|
Single unit innervation-
|
one neuron for many cells - lots of gap junctions
|
|
|
multi unit innervation
|
one neuron for one cell - not many gap junctions
|
|
|
Parts of small intestines
|
Duodenum, jejunum, ileum
|
|
|
Parts of large intestines
|
cecum, colon, rectum
|
|
|
chyme
|
solution of fragments of proteins and polysacharides
|
|
|
4 processes carried out by gi tract
|
digestion, absorption, motility, secretion
|
|
|
How do most molecules move in gi tract?
|
diffusion also by facilitated diffusion and active transport
|
|
|
What aids gi for diffusion?
|
increased surface area, increased gradient, and thin membrane
|
|
|
ingestion-
mastication- deglutition- peristalisis- |
taking food into the mouth
chewing and mixing food w/ saliva swallowing food wave like contractions |
|
|
The 2 types of movement in GI
segmentation- peristalsis(mass movement)- |
mixing movements - small intestines
periodic propulsion - slow, |
|
|
Where is skeletal muscle found in Gi?
|
at both ends -- tounge, upper esophagus, upper esophaus sphincter, external anal sphincter
|
|
|
What is the pressure difference in the smooth intestines for peristalisis to occur in SM?
|
higher pressure at pyloric end than at distal end
|
|
|
Give examples of exocrine and endocrine secrertions in the gi tract
|
exocrine - Hcl, h20, lipase,
endocrine - stomach and small intestine secrete hormones to help regulate the Gi --- gastine secretin cck and GIP |
|
|
digestion-
absorption- storage & elimination - |
-breakdown of food particles into subunits
-process of the passage of digestion into blood or LYMPH -tempoary storage and elimnation of indigestible food |
|
|
Name the enzymes that break down 1. fat 2. protein 3. polysaccharides
|
1. fat=lipase 2. protein =carboxypeptidase, trypsin, chymotrypsin, elastase 3. amylase
|
|
|
When is the movement of food initiated?
|
when pressure receptors in wall of pharynx are stimulated by food or drink
|
|
|
What is the swallowing reflex coordinnated by what? and what nerves are used
|
medulla oblongata which sends signal by efferent nerves to muscles of pharynx esophagus and respiratory muscles
|
|
|
What signals peristalsis?
|
localized reflexed in response to distention of wall by bolus
|
|
|
How is the food moved by peristalsis?
|
circular smooth muscle contract behind and relax in front of the bolus -- followed by longitudinal contraction of smooth muscle
|
|
|
How does saliva protect and digest?
|
protect -- antibacterial and bicarb buffers acid to protect teeth
digestive - salivary amylase -digests starch but not cellulose |
|
|
When does the symptoms of heartburn, gastroesophageal reflux disease or esophagitis (GRD GERD) commonly occur/
|
large meals, preg, obesity, alcohol consumption
|
|
|
Factors that lead to heartburn, gastroesophageal reflux disease or esophagitis (GRD GERD)
|
1.pressure in stomach > esophagus
2. efficiency of lower esophageal sphincter 3. acidity of regurgitated contents |
|
|
3 parts of the stomach
|
1.fundus 2. body 3. antrum
|
|
|
What is the abundant smooth muscle for in the stomach?
|
responsible for gastric motility
|
|
|
What does the body of the stomach secrete?
|
mucus, pesinogen, and HCl
|
|
|
What does the antrum of the stomach secrete?
|
mucus, pepsinogen and gastrin
|
|
|
What does chief cells secrete?
|
pepsinogen
|
|
|
What does parietal cells secrete?
|
HCl
|
|
|
What tends to empty out of the stomach slower than other contents?
|
Fats
|
|
|
What helps reabsorb H20 in large intestines?
|
active transport of Na, coupled with osmotic absorption of water
|
|
|
Name layers of GI tract wall lumen 1st
|
mucosa, submucosa, muscularis externa, serosa
|
|
|
Name 3 things in mucosa and their purpose
|
lamina propria - thin layer of ct containing lymph
muscularis mucosae - smooth muscle responsible for folds goblet cells- mucus |
|
|
Submucosa of Gi--
Purpose of submucosal plexus - |
-thick highly vascular layer of ct
-absorbed molecule enter the blood and lymph vessels -provide innervation to muscularis mucosae of mucosa |
|
|
muscularis externa-
|
responsible for segmental contractiosn and peristaltic movement through gi
|
|
|
What is located in between the two layers of muscles (inner circular and outer longitudinal) of hte muscularis externa
|
myenteric plexus - major nerve supply to gi from both para and sympathetic
|
|
|
Purpose of serosa layer in gi tract wall?
|
binding and protective layer -consists of ct with simple squamous epithelium
|
|
|
What is acid produced by and what is its production dependent on?
|
parietal cells and depends on generation of carbonic acid
|
|
|
What are 3 stimulatory and 1 inhibiatory signal of parietal cells?
|
Stimulatory - gastrin, histamine, Ach
inhibitory - somatostatin |
|
|
Where is trypsinogen released from? and where is it activated?
|
Released from pancreas and activated by intestine by membrane bound enterokinase
|
|
|
What are monosacchardies and amino acids absorbed by in the intestinal epithelial cells?
|
Specific transporters
|
|
|
How do fatty acids enter cells?
|
by diffusion
|
|
|
Through what are secretions from the liver and pancrease delivered to the small intestines?
|
Sphincter of Oddi
|
|
|
Is exo or endo pancrease function important for digestive function?
|
Exocrine -- exocrine glands have ducts that carry their secretions to a specific location
|
|
|
Where is bile made? stored?
|
made in liver and stored in gall bladder
|
|
|
How many grams of fat do we average daily?
|
70-100 g/day
|
|
|
Where does digestion of fats primarily occur?
|
small intestines
|
|
|
What does pancreatic lipase split TG into?
|
2 fatty acids, and monoglyceride
|
|
|
Where does fat accumulate in stomach?
|
as droplets in upper portion
|
|
|
What are 2 examples of emulsifing agents?
How do they work? |
phospholipids in food and bile salts -- convert large fat globules tinto smaller pieces with polar surfaces that inhibit reaggregation
|
|
|
Why is bile good for fat digestion?
|
its amphipathic
|
|
|
Purpose of chylomicron-
|
found in blood and lymphatic fluid where they serve to transport fat from port of entry in the intestine to the liver and to the adipoose tissue
|
|
|
What is the path of fat from lumen to systemic vein
|
fat, droplet, micelles, fatty acids and monoglyerides, (enters epithelium) reforms TG with enzymes of ER, then forms chylomicron and enters lacteal
|
|
|
What intake of carbs is recommended for humans?
|
250-300 g/day
70% plant and 30% sucrose/lactose |
|
|
Where does digestion of carbs begin and end?
|
begins in mouth with salivary amylase-- small intestines by pancreatic amylase -- brush boarder enzymes
|
|
|
How does monosaccrides get into epithelial cells? blood?
|
epithelial cells- facilitated transport or 2ndary active transport
into blood -facilitated transporters |
|
|
How much protein in needed daily?
|
40-50 g/day most get 70-90q
|
|
|
Where is protein digestion started?
|
starts in stomach with pepsin and then small intestines by trypsin and chymotrypsin from pancreas
|
|
|
carboxypeptidase -
aminopeptidase - where are they made |
carboxypeptidase - from pancreas
aminopeptidase - from epithelial cells in small intestines |
|
|
What type protein enter epithelial cells ?
|
di and tri peptides enter epithelial cells and spilt into single amino acids which leave cell to blood by SPECIFIC facilited carriers
|
|
|
Pancreatic amylase -
|
digest starch to oligosacchardies (small saccharide) - the oligosacchardies are hydrolyzed by brush boarder enzymes
|
|
|
How does monosaccharides get across the brush boarder?
|
active transport
|
|
|
How does monosaccharides get into portal blood?
|
faciliated transport
|
|
|
what does lactase do?
|
breaks down 2-sugar lactose to glucose and galactose
|
|
|
Why lactose intollanace create gas and bloating?
|
disacchardie is not absorbed and bacteria in large intestines eat the sugar and go crazy -
|
|
|
How to over come lactose intolerance?
|
consuming lactase -but not on an empty stomach and how the enzyme enters the small intestines at the same time as the food
|
|
|
Where is protein digestion started? where does most of the digestion occur?
|
Started in the stomach and most done by pancreatic peptidases in duodenum
|
|
|
leptin -
|
released from fat and influences food intake - satiety - decreased appetite
|
|
|
ghrelin
|
released from stomach during fasting --increased appetite
|
