LECTURE 4 - salivary glands, oesophagus, stomach microanatomy

Question 1

where is the myenteric nerve plexus found

Answer 1

between the inner circular and outer longitudinal layers of muscularis externa

Question 2

what movement does the myenteric nerve plexus help with

Answer 2

peristalsis

Question 3

where is the submucosal plexus found

Answer 3

in the submucosa

Question 4

what is the function of the submucosal plexus

Answer 4

helps control movement and function of the mucosa eg stimulating muscularis mucosae to contract

Question 5

what are 2 types additional folds which increase the SA in the digestive system

Answer 5

transient eg rugae of stomach

permanent eg plicae circularis of SI

Question 6

which nervous system controls the myenteric and submucosal plexuses

Answer 6

ENS which is controlled by the ANS

Question 7

how does the eplithelium of the mucosa receive oxygen and nutrients

Answer 7

by diffusing from BV in the lamina propria

Question 8

what are the 3 functions of the epithelium in the mucosa

Answer 8

protection
secretion
absorption

Question 9

what are the 3 sublayers of the mucosa

Answer 9

epithelium
lamina propria
muscularis mucosae

Question 10

what is the structure of the lamina propria

Answer 10

made of CT fibres and loose areolar CT

Question 11

what is the function of the lamina propria

Answer 11

functional support- packed with bv, nerves to support teh functions of the epithelium

structural support-

Question 12

what is the function of the muscularis mucosae

Answer 12

provides movmenent to the mucosa independent of peritalsis

= squeezes glands to move secretions

Question 13

what marks the boundary between the mucosa and the submucosa

Answer 13

the muscularis mucosae

Question 14

what is the muscularis mucoase made out of

Answer 14

only made up of smooth muscle

Question 15

what controls the muscularis mucosae

Answer 15

the eneteric nervous system which is under control of teh autonomic ns

Question 16

what is the function of the submucosa

Answer 16

same as lamina propria

Question 17

what is the structure of the musclaris externa

Answer 17

inner circular and outer longitudinal

Question 18

function of muscularis externa

Answer 18

coordinated contraction of these 2 generates peristalsis

Question 19

where do you find serosa vs adventita

Answer 19

serosa- when the structure is in contact with space

adventita- when structure is next to adjacent structure

Question 20

what is the serosa

Answer 20

visceral peritoneum

Question 21

what is adventita

Answer 21

ct between 2 adjacent structures

Question 22

what are intraperitoneal organs covered in

Answer 22

serosa ie visceral peritoneum- lined with a single layer of squamous mesothelium

Question 23

what are retroperitoneal organs covered in

Answer 23

have serosa / visceral peritoneum on anterior surface only and have adventita on their posterior srface

Question 24

what are the 3 main types of salivary glands

Answer 24

parotid
submandibular
sublingual

Question 25

which salivary glands have a serous secretion

Answer 25

parotid

Question 26

which salivary glands have a mixed secretion

Answer 26

submandibular

Question 27

which salivary glands have a mucus secretion

Answer 27

sublingual

Question 28

which salivary glands have a dark sttain

Answer 28

parotid glands- have a watery secrtion (have serous cells)

Question 29

what gives these salivary glands their dark stain

Answer 29

zymogen granules in the cytoplasm

Question 30

what do zymogen granules in the serous cells do

Answer 30

contain amylase which breaks down carboyhdrates

Question 31

where are myoepithelial cells found

Answer 31

on the periphery of serous acinus and mucous acinus

Question 32

what is the function of myoepithelial cells

Answer 32

contract and squeeze acinar secretions into the lumen and facilitate the release of secrtions

Question 33

where are the nuclei located in individual serous cells

Answer 33

located centrally

Question 34

which salivary glands have a light stain

Answer 34

sublingual glands (mucus cells)

Question 35

why are sublingual glands paile staining

Answer 35

because mucus granules do't pick up dyes

Question 36

where are the nuclei in mucous acinus

Answer 36

peripheral and flattened due to mucus granules

Question 37

what type of ducts are striated ducts

Answer 37

interlobular

Question 38

why do striated ducts look striated>

Answer 38

they have mitochondria aligned in columns

Question 39

function of striated ducts

Answer 39

extract Na+ and Cl- from secretions passing over and by metabolism generate bicarbonate HCO3- and K+ ie an exchange occurs

Question 40

what is the function of HCO3-

Answer 40

regulates balance by neutralising acid secrtions

Question 41

hierarchy starting from submandibular duct

Answer 41

subandibular duct- interlobular duct- intralobular duct

Question 42

3 functions of saliva

Answer 42

lubrication, protection, digestion

Question 43

function of carbohydrate rich glycoproteins (mucins) in saliva

Answer 43

lubrication and protection (bacterial adhesion)

Question 44

function of bicarbonate ions in saliva

Answer 44

protect against bacterial secretions and neutralise acidic vomit

Question 45

function of lysozyme in saliva

Answer 45

break down bacterial cell walls

Question 46

function of lactoferrin in saliva

Answer 46

targets iron dependent bacteria

Question 47

function of immunoglobulin A in saliva

Answer 47

fights bacteria and viruses

Question 48

function of amylase in saliva

Answer 48

breaks down carbs

Question 49

function of lipase in saliva

Answer 49

breaks down fats

Question 50

function of haptocorrin in saliva

Answer 50

vitamin B12- protects Vit B12 from acidic environment of stomach

Question 51

which nervous system controls salivary secretion

Answer 51

the autonomic nervous system (parasympathetic and sympathetic)

Question 52

when does salivary secretion increase

Answer 52

when the parasympathetic nervous system is stimulated sight and thought of food nausea

Question 53

when does salivary secretion decrease

Answer 53

``` when the sympathetic nervous system is stimulated fatigue sleep fear dehydration exercise ```

Question 54

what does the Parasymp NS do to increase salivary secretion

Answer 54

accelerates secretion resulting in producing large amounts of watery saliva myoepithelial cells contract increased blood flow

Question 55

what does the symp ns do to decrease salivary secretion

Answer 55

secretion of a small volume of viscous saliva containing high enzyme concentrations, reduced volume produces the sensation of a dry mouth blood vessels constricted

Question 56

what state is the oesophagus normally in

Answer 56

normally collapsed with folds of mucosa when empty and only expands when bolus or water moves through

Question 57

epithelium of oesophagus

Answer 57

thick sacrificial stratified squamous epithelium (non- keratinised by contains a small amount of keratinohyalin granules)

Question 58

how does the epithelium change when it moves into the stomach

Answer 58

transitions into simple columnar/cuboidal as it approaches the stomach

Question 59

how is the muscularis mucosae different in the oesophagus

Answer 59

absent/rare near the upper oesophagus but developed near the stomach

Question 60

function of the muscularis mucosae in the oesophagus

Answer 60

permits independent movement and folding of the mucosa aiding digestion and absorption

Question 61

how does the muscularis externa of the oesophagus differ

Answer 61

skeletal muscle is present in the pharyngeal end | however at the gastric end there is only smooth muscle

Question 62

describe the process of peristalsis

Answer 62

contraction of circular muscles behind bolus contraction of longitudinal muscles ahead of bolus contraction in circular muscle laer forces bolus forward

Question 63

what are the 4 key regions of the stomach

Answer 63

fundus, body, pylorus, cardia

Question 64

function of stomach

Answer 64

storage tank digestion= sterilisation, sercretion, digestion absorption

Question 65

where in the stomach are the parietal glands found

Answer 65

in the body and fundus of the stomach

Question 66

what do parietal glands secrete

Answer 66

HCl intrinsic factor pepsinogen somatostatin

Question 67

which areas of the stomach mainly have mucus secretions

Answer 67

cardia and pylorus (beginning and end)

Question 68

what do pyloric glands secrete

Answer 68

pepsinogen mucus gastrin somatostatin

Question 69

how does the muscularis externus differ in the stomach

Answer 69

has an extra innermost oblique layer which allows churning in 3D

Question 70

functional of simple columnar mucus cells

Answer 70

protective

Question 71

what are the 4 ways in which the simple columnar mucus cells are protective

Answer 71

1. mucus coat (secreted by mucus granules) 2. secrete insoluble alkaline mucus 3. phospholipid enrichment 4. high turnover of cells

Question 72

what do mucus neck cells secrete

Answer 72

soluble acidic glycoproteins

Question 73

what do simple columnar mucus cells secrete

Answer 73

insoluble alkaline/neutral glycoproteins which form a protective mucus bicarbonate

Question 74

what do parietal cells secret

Answer 74

intrinsic factor | hcl

Question 75

what does the HCl secreted by parietal cells do to pepsinogen

Answer 75

acttivates it converting it to pepsinogen

Question 76

which cell secretes pepsinogen

Answer 76

chief cells

Question 77

what does pepsin do

Answer 77

break down proteins to amino acids

Question 78

enteroendocrine 3 cells

Answer 78

G cells - gastrin ECL cells- histamine D cells - somatostatin