LEC 1

Question 1

Layers of the GIT

Answer 1

1. Mucosa
2. Sub-mucosa
3. Muscularis propria (externa
4. Adventia layer (or serosa):

Question 2

Mucosa including

Answer 2

1. epithelium
2. the lamina propria
3. muscularis mucosa

Question 3

the lamina propria

Answer 3

*loose connective tissue 
CONTAIN 
1.mucosal glands,
2.vascular support for the epithelium
3.Lymphoid follicles and plasma cells 
4.Products of digestion 
within Mucosa احد 
مكونات الmucosa

Question 4

muscularis mucosa

Answer 4

thin double layer of SM for local movement of the mucosa

Question 5

Sub-mucosa

Answer 5

1. SECOND layer of GIT
2. larger blood vessels
3. lymphatic vessels,
4. nerves, and can contain mucous secreting glands.

Question 6

Muscularis propria (externa)

Answer 6

two smooth muscle layer
1.inner layer is circular
2.outer layer is longitudinal
→excitation of one of these layers often excites the other as well
→because a few connections exist between the longitudinal and circular muscle layers

Question 7

inner layer of Muscularis propria (externa)

Answer 7

circular

contraction→ ↓ diameter

Question 8

outer layer of Muscularis propria (externa)

Answer 8

longitudinal

contraction→ ↓ shorting

Question 9

Adventia layer (or serosa)

Answer 9

covered by the visceral peritoneum.
Contains blood vessels, lymphatics and nerves
4th layer

Question 10

SM fibers in the GIT are

Answer 10

200 to 500 micrometers in length
2 to 10 micrometers in diameter
arranged in bundles of as many as 1000 parallel fibers

Question 11

bundle of smooth muscle fibers

Answer 11

1. is partly separated from the next by loose connective tissue
2. fuse with one another at many points

Question 12

Mechanical connection between smooth muscle fibers

Answer 12

smooth muscle fibers the muscle bundles fuse with one another at many points,

Question 13

chemo-receptors

Answer 13

activated by H+, proteins, and lipids in chyme),

Question 14

mechano-receptors

Answer 14

activated by distension of the digestive walls by food (bolus or chyme)

Question 15

osmo-receptors (

Answer 15

activated by amino acids and glucose

Question 16

Parasympathetic pathway

Answer 16

Pre-ganglionic→ enteric plexuses→ Post-ganglionic →to the smooth muscle
→ secretory cells
→ endocrine cells of the GIT

Question 17

The vagus nerve innervates

Answer 17

the esophagus, stomach, pancreas, and upper large intestine.

Question 18

The pelvic nerve innervates

Answer 18

the lower large intestine, rectum, and anus.

Question 19

vagovagal reflexes

Answer 19

Reflexes in which both afferent and efferent pathways are contained in the vagus nerve

Question 20

Sympathetic nerve originate in the spinal cord between

Answer 20

T-8 and L-2

Question 21

Extrinsic nerves functions

Answer 21

1.to coordinate activity between different regions of the digestive system
2.influence digestive tract motility and secretion either by
modifying تحويرongoing activity in the intrinsic plexuses,
altering تغيرthe level of gastrointestinal hormone secretion
 acting directly مباشر تأثيرon the smooth muscle and glands

Question 22

major neurotransmitters

Answer 22

1) acetylcholine, (2) norepinephrine, (3) adenosine triphosphate, (4) serotonin, (5) dopamine,
(6) cholecystokinin, (7) substance P, (8) vasoactive intestinal polypeptide, (9) somatostatin, (10)
leu-enkephalin, (11) met-enkephalin (12) bombesin and (13) nitric oxide

Question 23

neuropeptides

Answer 23

1. short chains of amino acids

2. act as hormones or neurotransmitter.

Question 24

criteria of neurotransmitter

Answer 24

1. present within the presynaptic neuron
2. released in response to presynaptic depolarization
3. receptor spresent on the postsynaptic cell

Question 25

Acetylcholine

Answer 25

excites gastrointestinal activity

Question 26

Norepinephrine/epinephrine

Answer 26

inhibits gastrointestinal activity

Question 27

Enteric nervous system plexuses

Answer 27

1. submucosal plexus

2. myenteric plexus

Question 28

Enteric nervous system location

Answer 28

1 in the wall of the gut
2.beginning in the esophagus and extending to
the anus

Question 29

little brain.”

Answer 29

Enteric nervous system

Question 30

function of ENS

Answer 30

1.generates and modulates motility and secretion without input from CNS
2.integrates and coordinate
 motility,
secretory, and
endocrine functions of the GI tract
3.relays information from the parasympathetic and sympathetic

Question 31

Myenteric plexus called

Answer 31

Auerbach’s plexus)

Question 32

The myenteric plexus consists of

Answer 32

linear chain of many interconnecting

neurons

Question 33

The myenteric plexus is located

Answer 33

between the circular and longitudinal smooth muscle

layers

Question 34

the myenteric plexus function

Answer 34

controlling muscle activity along the length of the gut.
1. ↑ tonic contraction
2 ↑rhythmical the of intensity)
3.↑rate of the rhythm of contraction
4.↑velocity of conduction of excitatory waves

Question 35

The myenteric plexus considered

Answer 35

excitatory +inhibitory

Question 36

myenteric plexus inhibitory

Answer 36

secrete VIP inhibiting intestinal sphincter muscles.

Question 37

Sub-mucosal plexus also called

Answer 37

Meissner’s plexus

Question 38

The submucosal plexus is location

Answer 38

between the inner layer of the circular muscle layer and the submucosa

Question 39

The submucosal plexus controll

Answer 39

secretion and blood flow

2. local absorption
3. contraction of the sub-mucosal muscle

Question 40

the cause of folding of the

gastrointestinal mucosa

Answer 40

contraction of the sub-mucosal muscle

Question 41

intrinsic primary afferent neurons [IPANs]

Answer 41

that sense the
environment so can be stimulated by
chemoreceptors: any chemical changes (eg, intestinal pH, osmorlality, irritation (toxins)
 mechanoreceptors wall stretch

Question 42

secreto-motor or efferent neurons

Answer 42

that control all facets of digestive tract activity
motility, 
 secretion,
 absorption
 immune function