What are the functions of the digestive system?
- 1. get food and water
- 2. store food
- 3. make mucous to lubricate and soften food
- 4. digest food
- 5. absorb nutrients
- 6. eliminate waste
- 7. kill bacteria
- 8. make hormones
Objects in the gut's lumen are considered to be in an external environment because
They are outside of tissues
Name the pathway of the digestive system starting with the mouth.
Mouth -> oral cavity -> pharynx -> esophagus -> stomach -> small intestine -> large intestine -> rectum -> anus
Name the accessory organs of the digestive system
- 1. salivary glands
- 2. pancreas
- 3. liver and gall bladder
- 4. cecum and appendix
What are the cross-sections of the gut lumen?
mucosa, submucosa, submucosal nerve plexus, circular smooth muscle layer, myenteric nerve plexus, longitudinal smooth muscle layer, serosa, and the mysentery.
What is an important aspect of the gut? And how has the body evolved to maximize this functionality? (it has to do with food)
- - absorption of nutrients and vitamins
- - created invaginations, villi, and microvilli to maximize the surface area for absorption.
What is the purpose of exocrine glands of the digestive system?
Exocrine glands of the digestive system secrete liquids and mucous to help lubricate and help digest foods.
The body uses which three monosaccharides?
glucose, galactose, fructose
The stomach secretes pepsin to do what?
Amino acids are absorbed into the blood stream how?
They are transported by secondary active transport across the intestinal lining.
Where does fat/lipid digestion begin? What is used to help digest the fats?
In the intestine. Bile, cholesterol, phospholipids. lipase enzymes then digest the fats.
What is an emulsifier?
Allows fat droplets to remain in solution instead of separating out.
What is a chylomicron?
A triglyceride-rich lipoprotein
what is the difference between a lipoprotein and a apolipoprotein?
apolipoprotein: lipid-binding proteins
lipoproteins: particles made of triglycerides, cholesterol and apolipoproteins. Used for transporting large amounts of triglycerides throughout the body.
Where do chylomicrons enter?
The lymphatic lacteals
Which of the vitamins are special and need something special to help it be absorbed by the body?
Vitamin B12 which needs a protein called: intrinsic factor to help it get across the wall by endocytosis.
How much water is secreted into the stomach and how much of it exits along with fecal matter?
How are (+) and (-) ions absorbed?
(+) = active transport
(-) = diffusion following the (+) ions
Which molecules move through the gut through active transport?
What kind of neural control is applied to the digestive system?
The majority of nueral impulse on the digestive system is that of smooth muscle contraction and gland secretion. There are some endogenous rhythms.
Long reflex neural regulation of the digestive system is what?
Regulation of the digestive system by the parasympathetic and the sympathetic nervous system
Short reflexes of the digestive system are what?
Regulation of the digestive system using the nerves of the submucosal and myenteric plexus
The enteric nervous system is sometimes referred to as what?
The third division of the autonomic nervous system
The enteric nervous system is independent/dependent on the central nervous system.
It is independent, but its actions can be altered by the autonomic N.S and through endocrine/paracrine signals
Which three cells are most gastrointestinal hormones and paracrines secreted?
enteroendocrine, enterochromaffin, and APUD cells.
What do Gastrin, Secretin, Cholecystokinin, GIP, and Motilin do?
- Gastrin: Stim HCl, histamine, and pepsinogen secretion
- Secretin: Stim HCO3 secretion in the duodenum and inhibits gastrin secretion.
- Cholecystokinin: Stimulates pancreatic enzyme secretion and bile release from liver and increases the effect secretin-induced pancreatic and hepatic HCO3 secretion
- GIP: Stim insulin production and inhibits gastrin secretion
- Motilin: Stimulates motility along the small and large intestine
What are the 3 phases of digestive regulation?
- 1. cephalic phase
- 2. gastric phase
- 3. intestinal phase
The swallowing reflex is controlled by the __?
What is chyme?
Partially digested food
What are the two forms of peristalsis that are done in the small intestine?
1. segmentation: slow back and forth movement
2. Migrating motility complex: fast movement of food pushing it to the large intestine.
Both the large intestine and the small intestine both undergo
Segmentation and peristalsis
After being absorbed into the small intestine where does glucose first go?
To the liver
How is glucose stored?
As glycogen and triglycerides
Proteins are broken down by ____ and used to _______. They can also be converted into _____ and ____.
Protein anabolism, build other proteins, glucose, triglycerides
How are triglycerides stored?
They are taken to adipose tissues where they are broken down into parts and then enter the adipose cells. They are then reformed to be stored in those tissues. Some triglycerides are also used in B-oxidation for energy.
What is the postabsorptive state?
The time between 2 meals where no dietary nutrients are available and stored nutrients need to be used.
what is glucose sparing?
The use of other molecules for E in order to prevent the removal of glucose from the blood stream.
What are the islets of langerhans?
Islands of cells in the endocrine pancreas that are made of alpha and beta cells.
Alpha cells secrete: glucagon
Beta cells secrete: insulin
What factors affect blood glucose levels?
- 1. Sympathetic nervous system
- 2. Parasympathetic nervous system
- 3. Epinephrine
- 4. Cortisol
- 5. Growth Hormone
- 6. Thyroid Hormone
How is cholesterol lost?
urine, sloughed off cells, and feces