Ward Gastric Physiology of digestion Flashcards
(blank) are secreted from the mouth to the terminal regions of the intestine.
digestive enzymes
(blank) is secreted throughout the GI tract by glands to provide lubrication and protection of the epithelial lining.
mucus
What are the two primary types of secretion?
digestive enzymes
mucus
What are the four types of glands associated with secretion?
single cell mucous glands
crypts of Leberkuhn
Tubular glands
Salivary glands, pancreas and liver
What is this:
(mucous cells/goblet cells) Are located in the epithelium and are found in most parts of the GI tract and respond to local stimulation of the epithelium by extruding their mucus onto the epithelial surface to act as a lubricant and to protect the epithelial surface.
Single cell mucous glands
What is this:
These are in the small intestine and are invaginations of epithelium into the submucosa. These are usually deep and contain specialized secretory cells.
Crypts of Leiberkuhn
What is this:
Located in the stomach and upper duodenum are large numbers of deep tubular glands which often secrete acid and pepsinogen.
Tubular glands
What is this:
More complex glands with a primary function to provide secretions for digestion and emulsification of food. Two of these glands are compound acinus (containing many acinar cells) glands that lie outside the wall of the GI tract and are connected via ducts that empty into the GI tract itself.
Salivary glands, pancreas and liver
The (blank) and (blank) are compound acinus (containing many acinar cells) glands that lie outside the wall of the GI tract and are connected via ducts that empty into the GI tract itself.
salivary and pancreatic glands
Transportation of nutrient material needed for the formation of the secretory material must diffuse or be transported into the base of the glandular cell from (blank)
capillaries
Synthesis of the secretory substance occurs in the (blank) and (blank)
ER and golgi complex
The secretory substance is transported through the ER, passing into the (blank)
golgi complex
In the golgi, secretory substances are modified, concentrated and discharged into the cytoplasm in the form of (blank)
secretory vesicles
Secretory vesicles are normally stored in the (blank) ends of the cell until (blank) cause them to empty their contents through the cell’s surface.
apical ends
neural or hormonal signals
The mechanism by which the secretory vesicle fuses to the plasma membrane (exocytosis) is usually (blank) dependent.
calcium
The neural or hormonal substance causes an increase in (blank), which leads to a fusion of the secretory vesicle with the apical membrane.
intracellular calcium
Sufficient water and electrolytes need to be secreted along with (blank).
organic substances
Nerve stimulation has a specific effect on the (blank) portion of the cell membrane, causing (blank) transport of (blank) ions into the cell.
basal
active
Cl-
When you have nerve stimulation that causes active tranport of Cl- into the cell you have a resultant (blank) charge inside the cell which causes (blank) to move into the cell.
negative charge
Na+
When nerve stimulation causes Cl- to enter the cell and as a result, Na+ into the cell, the excess of both these ions inside the cell creates a (blank) condition within the cell and a force that does what?
hyperosmotic
OSMOTIC force -> pulls water into the cell increasing the hydrostatic pressure
The increase in hydrostatic pressure resulting from nerve stimulation and the subsequent increase in Na+ and Cl- ions into the cell causes (blank) of the secretory border. Release of water through these openings results in the flushing of (blank) and (blank) out of the apical end of the cell and into the lumen of the gland
minute rupturing
electrolytes and organic substances
The increase in hydrostatic pressure resulting from nerve stimulation and the subsequent increase in Na+ and Cl- ions into the cell causes minute rupturing of the secretory border. Release of water through these openings results in the flushing of electrolytes and organic substances out of the (blank) end of the cell and into the lumen of the gland
apical
The presence of (blank) in a particular segment of the GI tract causes glands, in that region and often in adjacent regions to secrete digestive juices.
food
What are the two types of local stimulation of the GI tract glands?
direct contact-> of food with glands
epithelial stimulation-> neural activity causes secretion
What kind of GI stimulation is this:
activates the autonomic nervous system via tactile, chemical and distension mechanisms. The increase in neural activity causes mucus glands and deeper glands in the mucosa to increase secretion.
Epithelial stimulation of GI tract glands
What is the parasympathetic stimulation of secretion?
increase rate of glandular secretion
- > upper portion of GI tract (Vagus)
- > distal portion of large intestine (Pelvic Parasympathetics)
What are the components of the upper GI tract that the parasympathetics increase stimulation of secretion in? What are these innervated by?
salivary glands esophageal glands gastric glands pancreas brunner's glands in Innervated by the vagus!
What parasympathetics innervate the distal portion of the large intestine?
the pelvic parasympathetics
Secretion in the remainder of the small and large intestine not innervated by parasympathetics is controlled how?
by local neural and hormonal stimuli in each segment of the gut
What is the sympathetic stimulation of secretion?
causes slight/moderate increase in secretion
constriction of blood vessels
When will sympathetic stimulation cause an increase in secretion?
if parasympathetic nerve stimulation of salivary glands is low. If parasympathetic stimulation of salivary glands is high,then sympathetic stimulation will result in a reduction in secretion.
Summarize the hormonal stimulation of secretion:
GI hormones (polypeptides) from stomach and intestines are liberated from mucosa in response to food. They are absorbed into circulatory system and carried to particular gland to stimulate secretion
What is saliva necessary for and what is it dependent on?
Speech and mucus
What are the 6 constituents of saliva?
serous secretion mucus secretion lactoferrin proteolytic enzymes thiocyanate ions binding glycoprotein for IgA