Lecture 45 & 46 - Digestion & Nutrient absorbtion Flashcards
Epithelium in the gut is an effective barrier for ________and their related _____
Epithelium in the gut is an effective barrier for pathogens and their related toxins
The control systems of the gut involves the :
CNS, ENS, Hormones and muscle
True or False:
Endocrine system acts on a minute time-scale
True
ENS lines the intestinal, lined the same way from mouth to anus.
What controls the mucosal epithelial cells?
Submucous plexus - contains arteries/arterioles and ENS nerves
What lies superficial to the submucous plexus?
deep muscular plexus
True or False.
The ENS is completely autonomous
True
True or False.
The PNS controls the regulation of motility and water and salt transport in the gut
False.
It’s the ENS
What is the state after a meal
Fed state
What happens in the fed state?
Stomach relaxes
Segmentation - push content/mixing
Peristalsis - propagates in anal direction
What happens in the fasted state?
Migrating motor complex, slowly propagating constriction that moves along whole length of small intestine
What happens in the mass movement contraction?
Defacation (colon, rectum
True and False
The peristalsis that occurs in the esophagus is controlled by the ENS
False.
Its by the PNS - by a means of swallowing
The final motor activity is the sum of the:
pacemaker activity and the neural activity
excitation and inhibition
True or False
Salivation, gastric acid secretion, gastric peptide secretion - the beginnings of the fed state can be started by cephalic input (i.e the sight of food)
True
The basic food groups are:
Carbohydrates
Proteins
Fats
Vitamins and minerals
Predominant location of breakdown and absorption is the…
Duodenum and jejunum
Digestion requires contact between food particles and digestive enzymes.
As such, vigorous ______ _____ for mixing and physical breakdown of foods exist.
Digestion requires contact between food particles and digestive enzymes.
As such, vigorous motor activity for mixing and physical breakdown of foods exist.
Digestion is mostly dependent on enzymes released from _____ ______
Digestion is mostly dependent on enzymes released from exocrine pancreas
The gut epithelium changes depending on the function of the tract at each point
The gut epithelium can be described as a monolayer of enterocytes
The gut epithelium changes depending on the function of the tract at each point
The gut epithelium can be described as a ______ of _______
Enterocytes have an apical surface exposed to the ______
Enterocytes have an apical surface exposed to the Lumen
Gut epithelial cells have a ______, where stem cells are produced
They then migrate to the _____ tip (in small intestine)
Gut epithelial cells have a crypt, where stem cells are produced
They then migrate to the villus tip (in small intestine)
True or False
There is a change from secretory to absorptive (water) as cells migrate from the crypt to the villi tip
True
Lasts 3-8 days
Amylase digests?
and where is it released?
Sugars, starches
Salivary and pancreatic
Glucose and galactose are transported by the ___-_____ ___ ________(SGLT) across the apical membrane of enterocytes
Glucose and galactose are transported by the sodium-glucose linked transporter SGLT across the apical membrane of enterocytes
Glucose and galactose are transported across the basolateral membrane by ____ _
Glucose and galactose are transported across the basolateral membrane by GLUT 2
Fructose crosses the apical membrane with ____ _
Fructose crosses the apical membrane with GLUT 5
Proteins are digested to _____ _____ and ___ ______
Proteins are digested to amino acids and short peptides
What is an endopeptidase?
What is an example?
Endopenetidases are responsible for breaking peptide bonds within an amino acid chain
Pepsin
What is an exopeptidase?
What is an example?
An exopeptidase is any peptidase that catalyzes the cleavage of the terminal (or the penultimate) peptide bond; the process releases a single amino acid or dipeptide from the peptide chain
Carboxypeptidases
Which cells are responsible for the secretion of Pepsin
Chief cells
What activates the chief cells?
acid pH (about 2), produced in stomach by H+ secretion from parietal cells - stimulated by Gastrin
From what is Trypsin secreted?
pancreas yo
What activates trypsin, chymotrypsinogen and procarboxypeptidase?
CCK - released from the duodenum enteroendocrine cells
How do single AAs cross the apical membrane?
via Na+ transporters
also cross the basolateral membrane via Na+ transporters
How do di-and tr-peptides cross the apical membrane?
via H+ coupled transporters
usually broken to AA’s within the cells consequently
Fats are broken by ______ in the mouth
lipase
You need ___to absorb the fats.
How does ____ help?
Bile
Bile salts coat fat droplets and together with mixing motility emulsify them.
What is the role of secretin?
Secretin is a hormone that both controls the environment in the duodenum by regulating secretions of the stomach and pancreas, and regulates water homeostasis throughout the body.
What is the role of cholecytokinin?
CCK is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein. Cholecystokinin, is synthesized by I-cells in the mucosal epithelium of the small intestine and secreted in the duodenum, the first segment of the small intestine, and causes the release of digestive enzymes and bile from the pancreas and gallbladder, respectively.
