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the secretory function of the GI tube

digestive enzymes to be secreted and secretion of mucus from mucus gland provide lubrication and protection

1

the glandar sturcture of the secretory function of the GI tract

mucous Gland , glandular pits(TUBULAR) , tubular glands, Acinar aveolar

2

single cell mucous gland

mucous cell( globlet cell) , it is found on the surface off the epithelium in the GI Tract, its function is to respond to irritation of the epithelium by the producing mucus, which acts as a protectant to the surface from excorination and digestion

3

Glandular Pits(tubular )

this represents invagination of the epithelium into the submucosa , in the small intestine this pits is called the cryptes of lieberkihn

4

Tubular Glands

In the stomach and upper duodenum

5

Acinar(alveolar)

found in the salivary glands, pancreas, and liver, provided secretion for digestion or emulsificatin of food, In the GI tract these acini feed into a system that empty into the allimentary tract. this are exocrine glands

6

Stimulation of the secretory Glands is by

presence of food, Autonomic nervous system, and hormones

7

the presence of food in the gi tract activates

the enteric nervous system of the gut wall, there is tactile sensation, chemical irritation, and distention of the gut

8

parasympathetic stimulation of gland

affects the rate of alimentary glandular secretion from the glands in the upper portion of the tract eg salivary gland, esophagus gastric glands, pancreas, brunner's gland( duodenum). this is innervated by the by the glossopharyngeal and vagus nerve

9

sympathetic stimulation of the secretory glands

cause moderate secretion by local gland, also resulting in constriction of blood vessels that supply the gland

10

dual effect of sympathetic stimulation

sympathetic stimulation will cause increase in secretion, but if parasympathetic or hormonal stimulation is in effect, then it will reduce stimulation

11

Hormones and stimulation of secretory glands

it regulates the volume and character of the secretion
the hormone are release from the GI mucosa in response to the presence of food
hormones are then absorbed into the blood and carried to the gland that will release secretion.

12

1 step of secretion of organic substance

1. materials needed for formation of secretion must diffuse or be actively transported by the blood in the capillaries into the base of the glandular cell via merocrine secretion

13

2 step of secretion of organic substance

mitochondria located in the glandular cells near its base uses oxidative energy to form ATP

14

3 step of secretion of organic substance

atp and appropriate substance provided by the nutrient is used to synthesize organic substance. this occurs in the ER and Golgi complex.

15

4th step of secretion of organic substance

the secretory material are transported through the tubules of the ER to the vesicle of the Golgi

16

5th step of secretion of organic substance

In the Golgi material are modified and discharged into the cytoplasm in from of secretory vesicle, which are stored at the apex of the cell until stimulated

17

--------stimulation causes water and salt to pass through the glandular cells

nervous stimulation

18

the mechanism for the movement or secretion of water and electrolyte through the cell is known as

apical flush out

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apical flush out mechanism step 1

nerve stimulation affects the basal portion of the cell causing an active transport of cl- into the cell

20

apical flush out mechanism step 2

the cell becomes more negative thus allowing for Na+ ion to move into the cell

21

apical flush out mechanism step 3

excess positive and negative ione causes water to enter the cell, increasing cell volume and hydrostatic pressure( the cell swells)

22

apical flush out mechanism step 4

the pressure in the cell causes the opening of secretory border flushing water, electrolyte, and organic substance out of the secretory end of the secretory glandular cell

23

name the salivary glands

Parotid, submandibular, and sublingual gland. There are also small buccal glands

24

name the types of salivary glands

serous secretion that contain ptyalin ( alpha amylase)
mucous secretion that contains mucin for lubrication and protection the GI tract surface.

25

parotid secretes

serous secretion

26

submandibular and sublingual secretes

both serous and mucus

27

buccal gland secretes

mucus

28

neural control of the the salivary gland and secretion is through

the parasympathetic nervous system by the superior and inferior salivatory nuclei in the brain stem

29

salivatory nuclei

it is in the brain stem, juncture between medulla and pons,and are excited by both tastes and tactile stimuli from the tongue and mouth and pharynx inhibits or stimulates via nervous signal of CNS