201 L13

Question 1

What are the 4 concentric layers (tunics) of the digestive system tube?

Answer 1

Mucosa
Submucosa
Muscularis externa
Serosa

Question 2

What is the inner most layer that is in contact with the lumen?

Answer 2

Mucosa

Question 3

What are the layers of the mucosa?

Answer 3

Epithelium
Lamina propria
Muscularis mucosa

Question 4

What are the functions of the epithelium in the mucosa layer?

Answer 4

Secretion - mucus, enzymes, acid

Protection - against friction/shearing, chemicals (acid)

Absorption - simple columnar, absorb nutrients that have been broken down in the small intestines

Question 5

The lamina propria of the ——- layer provides —— support in the form of ——— tissue

Provides ——— support in the form of —— vessels, ——– vessels, —— and —–.

Answer 5

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

Question 6

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 ———-

Answer 6

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

Question 7

What is the function of the submucosa.

Answer 7

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

Question 8

The —– —— usually has —– —– layers which are the —— ——– and —– ———.

The —– has — layers. An additional ——– ——– layer.

Usually are —— —— layers - except for the —– and —— which both have —– ——.

Answer 8

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.

Question 9

What is the function of the serosa?

Answer 9

Helps the gut organs to move against each other in a frictionless manner

Question 10

What does the serosa consist of?

Answer 10

Mesothelium - makes serous fluid which alloes the gut to move in a frictionless manner

Question 11

Is the serosa unique to the gut?

Answer 11

Yes

Question 12

What is adventitia?

Answer 12

outermost connective tissue covering of any organ, vessel or other structure.

Question 13

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

Answer 13

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

Question 14

What does the Meissner’s nerve plexus do and where is it located?

Answer 14

Located in the submucosa

Helps innervate the mucosa of the gut tube

Question 15

What makes up the enteric nervous system?

Answer 15

Myenteric and Meissner’s (submucosal) nerve plexus

Question 16

The ——– nervous system acts too control the —- functions ——– but is under the influence of the —— nervous system.

Answer 16

The enteric nervous system acts too control the gut functions independently but is under the influence of the autonomic nervous system.

Question 17

What structures increase the surface area for absorption in the small intestine?

Answer 17

Crypts and villi

Question 18

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.

Answer 18

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.

Question 19

Classify the structure of a salivary gland.

Answer 19

Compound tubuloalveolar

Question 20

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

Answer 20

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

Question 21

Name the salivary glands and their secretions.

Answer 21

Parotid gland - serous secretions only

Sublingual gland (mixed) - mostly mucus, has some serous

Submandibular gland (mixed) - mucus and serous secretions

Question 22

Name the salivary glands and their secretions.

Answer 22

Parotid gland - serous secretions only

Sublingual gland (mixed) - mostly mucus, has some serous

Submandibular gland (mixed) - mucus and serous secretions

Question 23

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.

Answer 23

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.

Question 24

Mucus acinus (cells in sphere with lumen)

—— granules occupy a lot of the —– and push the —– peripherally.

Viscous secretion

Surrounded by ———– cells

Answer 24

Mucus granules occupy a lot of the cytoplasm and push the nuclei peripherally.

Viscous secretion

Surrounded by myoepithelial cells

Question 25

——— acinus are —— secreting acinar cells capped off by ——- secreting acinar cells.

Answer 25

Mixed acinus are mucus secreting acinar cells capped off by serous secreting acinar cells.

Question 26

How do the secretions from the acinars get to the oral cavity

Answer 26

All the secretions come through ducts which converge and eventually get into the oral cavity through the major submandibular duct

Question 27

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 –.

Answer 27

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

Question 28

How can you tell serous acinors and mucus acinors apart?

Answer 28

The nuclei of mucus acinors are located at the periphery and are more elongated.

Question 29

What are the key functions of saliva?

Answer 29

Lubrication
Protection
Digestion

Question 30

What contributes to the lubrication function of saliva?

Answer 30

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

Question 31

Saliva — and offers a basic line of —— against – and — through certain —–.

Answer 31

Saliva protects and offers a basic line of defense against bacteria and viruses through certain mechanisms.

Question 32

What contributes to the digestive function of saliva?

Answer 32

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.

Question 33

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.

Answer 33

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.