PMS GI EXAM
1. What is the purpose and processes of the alimentary tract?: - provides the body with
water, electrolytes, vitamins, and nutrients
1. Movement of food
2. Secretion and digestion of juices breaks down food
3. Absorption of water, electrolytes, vitamins, and nutrients
4. Circulation: blood carries absorbed susbtances
5. Control: local, nervous, and hormonal systems regulate functions
2. What are layers of GI wall?: Outer to inner
1. Serosa
2. Longitudinal smooth muscle
3. Circular smooth muscle
4. Submucosa
5. Mucosa
3. Where is the Enteric nervous system located and what does it control?: - located
in gut wall from esophagus to anus
- controls GI movements and secretion
,4. What are main plexuses of ENS?: Myenteric plexus (Auerbach's plexus)
- between longitudinal and circular muscle layers
- controls movements
Submucosal plexus (Meissner's plexus)
- in submucosa
- controls secretion and local blood flow
5. What are the connections and functions of the ENS?: Connections
Extrinsic nerves: sympathetic and parasympathetic fibers enahnce or inhibit functions
Sensory nerves: send signals to ENS, prevertebral ganglia, spinal cord, and brain stem
Functions:
- can operate independently but influenced by extrinsic nerves
- elicits local and relayed reflexes
,6. What are differences between myenteric and submucosal plexuses?: Myenteric
- Location: between longitudinal and circular muscle layers
- Function: controls muscle activity along the gut
When stimulated, causes:
- increased tonic contraction
- increased intensity of rhythmic contractions
- slightly increased rate of contraction rhythm
- increased velocity of excitatory wave conduction
Has inhibitory neurons that secrete inhibitory transmitters to relax sphincter muscles
Submucosal
Location: in submucosa
Function: controls functions in the inner wall of intestine
- local intestinal secretion, absorption, contraction of submucosal muscle
7. What does extrinsic neural stimulation consist of?: Parasympathetic stimulation
- INCREASES ACTIVITY of the ENS
Sympathetic stimulation
- USUALLY INHIBITS GI activity
- strong stimulation: can greatly inhibit motor movements, potentially blocking food movement through tract
, Afferent sensory nerve fibers:
- originate from the gut
8. What are the types of GI reflexes?: 1. integrated within gut wall
- control secretion, peristalsis, mixing contractions, and local inhibitory effects
2. Gut to prevertebral sympathetic ganglia and back
- Gastrocolic reflex: stomach signals cause colon evacuation
- Enterogastric reflexes: colon and small intestine signals INHIBIT stomach motility and secretion
- Colonileal reflex: colon signal INHIBIT ileal emptying
1. What is the purpose and processes of the alimentary tract?: - provides the body with
water, electrolytes, vitamins, and nutrients
1. Movement of food
2. Secretion and digestion of juices breaks down food
3. Absorption of water, electrolytes, vitamins, and nutrients
4. Circulation: blood carries absorbed susbtances
5. Control: local, nervous, and hormonal systems regulate functions
2. What are layers of GI wall?: Outer to inner
1. Serosa
2. Longitudinal smooth muscle
3. Circular smooth muscle
4. Submucosa
5. Mucosa
3. Where is the Enteric nervous system located and what does it control?: - located
in gut wall from esophagus to anus
- controls GI movements and secretion
,4. What are main plexuses of ENS?: Myenteric plexus (Auerbach's plexus)
- between longitudinal and circular muscle layers
- controls movements
Submucosal plexus (Meissner's plexus)
- in submucosa
- controls secretion and local blood flow
5. What are the connections and functions of the ENS?: Connections
Extrinsic nerves: sympathetic and parasympathetic fibers enahnce or inhibit functions
Sensory nerves: send signals to ENS, prevertebral ganglia, spinal cord, and brain stem
Functions:
- can operate independently but influenced by extrinsic nerves
- elicits local and relayed reflexes
,6. What are differences between myenteric and submucosal plexuses?: Myenteric
- Location: between longitudinal and circular muscle layers
- Function: controls muscle activity along the gut
When stimulated, causes:
- increased tonic contraction
- increased intensity of rhythmic contractions
- slightly increased rate of contraction rhythm
- increased velocity of excitatory wave conduction
Has inhibitory neurons that secrete inhibitory transmitters to relax sphincter muscles
Submucosal
Location: in submucosa
Function: controls functions in the inner wall of intestine
- local intestinal secretion, absorption, contraction of submucosal muscle
7. What does extrinsic neural stimulation consist of?: Parasympathetic stimulation
- INCREASES ACTIVITY of the ENS
Sympathetic stimulation
- USUALLY INHIBITS GI activity
- strong stimulation: can greatly inhibit motor movements, potentially blocking food movement through tract
, Afferent sensory nerve fibers:
- originate from the gut
8. What are the types of GI reflexes?: 1. integrated within gut wall
- control secretion, peristalsis, mixing contractions, and local inhibitory effects
2. Gut to prevertebral sympathetic ganglia and back
- Gastrocolic reflex: stomach signals cause colon evacuation
- Enterogastric reflexes: colon and small intestine signals INHIBIT stomach motility and secretion
- Colonileal reflex: colon signal INHIBIT ileal emptying
