201 L13 Flashcards
Alimentary system
What are the 4 concentric layers (tunics) of the digestive system tube?
Mucosa
Submucosa
Muscularis externa
Serosa
What is the inner most layer that is in contact with the lumen?
Mucosa
What are the layers of the mucosa?
Epithelium
Lamina propria
Muscularis mucosa
What are the functions of the epithelium in the mucosa layer?
Secretion - mucus, enzymes, acid
Protection - against friction/shearing, chemicals (acid)
Absorption - simple columnar, absorb nutrients that have been broken down in the small intestines
The lamina propria of the ——- layer provides —— support in the form of ——— tissue
Provides ——— support in the form of —— vessels, ——– vessels, —— and —–.
The lamina propria of the mucosa provides structural support in the form of connective tissue
Provide functional support in the form of blood vessels, lymphatic vessels and cells, nerves
The muscularis mucosae of the ——— layer is a layer of ———– ——- that allows the movement of the —— that is independent of ———-.
When this ——- it specifically acts on the ———.
———– helps to squeeze ——— secretions and also produces movement of other ——– that are in the —– ——.
Boundary between the ——— and the ———-
Layer of smooth muscle that allows the movement of the mucosa that is independent of peristalsis
When this contracts it specifically acts on the mucosa
Contraction helps to squeeze glandular secretions and also produces movement of other vessels that are in the lamina propria
Boundary between the mucosa and the submucosa
What is the function of the submucosa.
Provides structural support with CT
Provides functional support with larger branches of blood vessels, lymphatics and nerves embedded within the submucosa
Sometimes can find submucosal glands - mucosal epithelial extensions into the submucosa
The —– —— usually has —– —– layers which are the —— ——– and —– ———.
The —– has — layers. An additional ——– ——– layer.
Usually are —— —— layers - except for the —– and —— which both have —– ——.
The muscularis externa usually has 2 muscle layers which are the inner circular and outer longitudinal.
The stomach has 3 layers. An additional innnermost oblique layer.
Usually are smooth muscle layers - except for the esophagus and anus which both have skeletal muscle.
What is the function of the serosa?
Helps the gut organs to move against each other in a frictionless manner
What does the serosa consist of?
Mesothelium - makes serous fluid which alloes the gut to move in a frictionless manner
Is the serosa unique to the gut?
Yes
What is adventitia?
outermost connective tissue covering of any organ, vessel or other structure.
Peristaltic functions
The peristaltic functions of the ——— ——— requires the coordinated actions of the —- ——– muscle layer and the ——- ——- muscle layer which ——– the tube.
This is coordinated by the
——— ——- —— which is positioned between the two layers of muscle
The peristaltic functions of the muscularis externa requires the coordinated actions of the inner circular muscle layer (constricts the lumen making a smaller diameter) and the outer longitudinal muscle layer which shortens the tube.
This is coordinated by the myenteric nerve plexus which is positioned between the two layers of muscle
What does the Meissner’s nerve plexus do and where is it located?
Located in the submucosa
Helps innervate the mucosa of the gut tube
What makes up the enteric nervous system?
Myenteric and Meissner’s (submucosal) nerve plexus
The ——– nervous system acts too control the —- functions ——– but is under the influence of the —— nervous system.
The enteric nervous system acts too control the gut functions independently but is under the influence of the autonomic nervous system.
What structures increase the surface area for absorption in the small intestine?
Crypts and villi
Sympathetic and parasympathetic
Responses associated with ——– activity are exercise, emotion and excitement.
These —— gut functions to divert —— to the brain and muscles. This predominates at times of ——.
Responses associated with ——– activity are Repletion, rest and relaxation.
These ——– gut functions during and after ——–. Stimulate — and —- in the gut tube.
Responses associated with sympathetic activity are exercise, emotion and excitement.
These inhibit gut functions to divert blood to the brain and muscles. This predominates at times of stress.
Responses associated with parasympathetic activity are repletion, rest and relaxation.
These promote gut functions during and after mealtime. Stimulate secretion and transport in the gut tube.
Classify the structure of a salivary gland.
Compound tubuloalveolar
Development of salivary glands
The ——– cells divide and multiply and continue to —– into ———– tissue gaining a
—— ——- structure
This results in ——- of ——— tissue that is separated by the connective tissue septa
The epithelial cells divide and multiply and continue to extend into connective tissue gaining a tubular alveolar structure
This results in lobules of glandular tissue that is separated by the connective tissue septa
Name the salivary glands and their secretions.
Parotid gland - serous secretions only
Sublingual gland (mixed) - mostly mucus, has some serous
Submandibular gland (mixed) - mucus and serous secretions
Name the salivary glands and their secretions.
Parotid gland - serous secretions only
Sublingual gland (mixed) - mostly mucus, has some serous
Submandibular gland (mixed) - mucus and serous secretions
Serous acinus (cells in sphere with lumen)
Secretion is —– and rich in —-.
In the cells ——- there are —— granules containing —— —–.
——– is an —– —- and helps to start the ——– of ———.
———– cells surround the acinar cells. These are modified ——- cells with —— properties that help to secrete the ——- granules into the lumen.
Secretion is water and rich in enzymes.
In the cells cytoplasm there are zymogen granules containing enzyme precursors (stained darkly).
Amylase is an enzyme precursor and helps to start the digestion of carbohydrates.
Myoepithelial cells surround the acinar cells. These are modified epithelial cells with contractile properties that help to secrete the zymogen granules into the lumen.
Mucus acinus (cells in sphere with lumen)
—— granules occupy a lot of the —– and push the —– peripherally.
Viscous secretion
Surrounded by ———– cells
Mucus granules occupy a lot of the cytoplasm and push the nuclei peripherally.
Viscous secretion
Surrounded by myoepithelial cells
——— acinus are —— secreting acinar cells capped off by ——- secreting acinar cells.
Mixed acinus are mucus secreting acinar cells capped off by serous secreting acinar cells.
How do the secretions from the acinars get to the oral cavity
All the secretions come through ducts which converge and eventually get into the oral cavity through the major submandibular duct
Striated duct
The membrane of the cells have the ——– formed due to abundant ——– between the —–.
The cell is producing a lot of ——- for ——- transport
- ——- and ——– ions pumped into the cell and
- —— and ——— pumped out of the cell
——— is an important buffer for maintaining –.
The membrane of the cells have the infoldings formed due to abundant mitochondria between the folds
The cell is producing a lot of energy for active transport
Sodium and chloride ions pumped into the cell and potassium and bicarbonate pumped out of the cell
Bicarbonate is an important buffer for maintaining pH
How can you tell serous acinors and mucus acinors apart?
The nuclei of mucus acinors are located at the periphery and are more elongated.
What are the key functions of saliva?
Lubrication
Protection
Digestion
What contributes to the lubrication function of saliva?
Mucins produced by the mucus asinus cells create a slippery surface in the oral cavity making it harder for bacteria and secretions to stick to the teeth
Saliva — and offers a basic line of —— against – and — through certain —–.
Saliva protects and offers a basic line of defense against bacteria and viruses through certain mechanisms.
What contributes to the digestive function of saliva?
Amylase helps with carbohydrate digestion. Broad pH range (4-11) but gets deactivated when HCl is present.
Lipase - helps start digesting fats, only activated in the stomach due to pH of 4
Kallikrein is involved in a pathway that increases the amount of blood flowing to the salivary glands. So indirectly it helps to rejuvenate and support the salivary glands.
Control of salivary secretion
Each salivary gland receives both ——— and ——- stimulation.
———— stimulation (thoughts of food) accelerates secretion, resulting in the production of large amounts of ——–, ——– cell contracts, increased —– flow.
————- stimulation (fatigue, sleep, fear, dehydration) results in a —– volume secretion of ———- saliva containing high ——– concentrations. ——— ——– are constricted.
Each salivary gland receives both sympathetic and parasympathetic stimulation.
Parasympathetic stimulation (thoughts of food) accelerates secretion, resulting in the production of large amounts of saliva, myoepithelial cells contracts, increased blood flow.
Sympatheic stimulation (fatigue, sleep, fear, dehydration) results in a small volume secretion of viscous saliva containing high enzyme concentrations. Blood vessels are constricted.
