unit 6 a and b Flashcards
Definition of digestion in the GI system
break macromolecules (nutrients) into forms that can be transported across epithelium
Definition of absorption in the GI system
transport nutrients, water, ions, vitamins across epithelium
Definition of secretion in the GI system
release of enzymes into gut lumen
Definition of motility in the GI system
keep the gut contents moving
Protection from pathogens mediated by…
(GAMED)
Gut Associated Lymphoid Tissue
Acid
Mucus
Epithelial barrier
Digestive enzymes
The three parts of the small intestine
Duodenum
Jejunum
Ileum
The four layers of the mucosal surface starting from the lumen outwards
Mucosa
Submucosa
Smooth muscle layers
Serosa
The mucosa can be described as three layers….
Epithelium
Lamina propria
Muscilaris mucosa
The stomach has ______ muscles which contract in a _______ direction
oblique
diagonal
Plica are unlike rugae in that they _____________ when stretched
Do not disappear
Within the villus molecules that cross the epithelium can go into the _______ and go into the blood or go into the _______ and go into the lymphatics
Venous capillary bed
Lacteal
The three way the small intestine increases surface area from smallest to largest
Microvilli
Villi
plica
During/after meals the smooth muscle will have _________ and ________ contractions
Peristaltic
Segmental
Between meals ________ sweep slowly down the tract
Migrating motor complexes
Single unit smooth muscle act as one unit because they are ____________
Coupled by gap junctions
The force and duration of muscle contraction in the GI is caused mostly by the _________ of action potentials
frequency
The slow wave frequency is set by ‘pacemaker cells’ between _______ called the ___________
Circular and longitudinal muscle layers
Interstitial cells of cajal
Ions mostly travel via ___________
Membrane transporters
The lumen of the stomach has __________ and ______ on the apical side
HK-ATPase
Cl leak channels
The lumen of the stomach has _______ on the basolateral side which causes bicarbonate to be ______ the blood
Bicarb chlorine antiporters
absorbed into
Why does Na get attracted into the lumen of the small intestine?
Negative chlorine ions in the lumen attract the sodium by the paracellular pathway, water will also follow
The NKCC transporter is on the _____ side of the small intestine
Basolateral
In the small intestine chlorine enters the lumen via apical __________
CFTR channels
The NaK- ATPase is on the _______ which allows for ______ reabsorption
Basolateral
Sodium (Na)
Bicarb is secreted into the _________ which neutralizes the acid arriving from the ______
Duodenum
Stomach
______ cells of pancreas secrete enzymes, epithelial cells lining ducts (duct cells) secrete __________
Acinar
bicarb solution
Lumen of small intestine bicarb secreted via __________ which is expressed on the _____ side
Cl-/HCO3- exchanger
Apical
Lumen of small intestine has NKCC transporter on the _____ side
basolateral
Cystic fibrosis is a mutation in gene that encodes ____________
CFTR channels
Cystic fibrosis can lead to defects in _____ and ____ transport which will cause _______ mucus
Cl and water
Thicker
The thick mucus caused by cystic fibrosis will lead to blockages of ________ ducts which causes exocrine secretions to not be realsed
Pancreatic ducts
Enzymes can be released as zymogens (__________) to prevent __________
Inactive precursors
Auto-digestion
Enzymes that are linked to microvilli can be called _____ _______ enzymes
Brush border
Mucus is produced by _______ cells
Exocrine
Name the exocrine cells in the salivary glands, stomach, and intestines respectively
Serous
Mucous
Goblet
Cytokines from immune cells can be a signal for ________
Mucus secretion
Fluid secreted by _______ cells is similar to ______. As it passes through _____, epithelial cells take back ___ and secrete ___ so that it resembles intracellular fluid
Acinar
ECF
Ducts
Na
K
_______ must first pass through liver before reaching systemic circulation
Xenobiotics
The three key components of bile
Bile salts
Bile pigments
Cholesterol
Digestion occurs in the _____, _______, and ________
Mouth
Stomach
Small intestine
Steps in absorption (6)
Lumen
Apical membrane
Epithelial cell
Basolateral membrane
Interstitium
Capillary/lymph
Carbohydrates can only be absorbed __________
Via membrane transporters
We only have membrane receptors for _____saccharides
mono
Glucose enters with Na on an ______ and exits on _______
SGLT
GLUT2
Fructose enters on ______ and exits on _____
GLUT5
GLUT2
________ digests internal peptide bonds
endopeptidase
Di and tri peptides cotransport with ____, amino acids cotransport with _____
H
Na
Fat soluble vitamins (4)
A D E K
Water soluble vitamins
C and most Bs
Except B12
The two substances for which interstitial absorption is regulated
Iron calcium
Feedforward reflexes originate ____ the GI tract and include the _____ reflexes
Outside
Cephalic
Neurons in _________ plexus regulate secretion, neurons in _______ plexus regulate motility
submucosal
myenteric
The two short reflexes regulate _____ and ______
Secretion
Motility
Short reflexes are integrated in the ____ nervous system
Enteric
Long reflexes are integrated in _____, short reflexes integrated in _____
CNS
Gut
Parallels between enteric and CNS
DING C
Diffusion barrier
Intrinsic neurons
Neurotransmitters
Glial support cells
Integrating center
The three families of gut hormones
Gastrin
Secretin
Motilin
3 steps of swallowing reflex
Tongue pushes bolus to the back of the mouth, triggering the reflex
breathing is inhibited
food moves down esophagus propelled by peristaltic waves and helped by gravity
The swallowing reflex is integrated in the ______
Medulla
If LES is not closed acid from the stomach can splash into lower esophagus, when this occurs during churning of the stomach it is called _______
GERD or heartburn
The cephalic phase increases _____ and _______ in the _____, ______, and _______
Motility
Secretion
Stomach
Intestine
Accessory organs
Cephalic phase of digestion is triggered by ________
Sight, smell, or sound of food
The long vagal reflex is the ______ phase
Cephalic
When food enter the stomach a series of _____ reflexes is triggered known as the _____ phase
Short
Gastric
