Lec 1

Question 1

Git own brain ?

Answer 1

1- submucosal ( messiner ) plexus : reseponsible for secretion of gland
2- myentric ( aurbach ) plexus : responsible for motality ( between circuler , longitudinal)

Question 2

GIT INNERVATION ?

Answer 2

1- submucosal

2- myentric

3- autonomic
• sympathetic: lesser/ greater splencinc nerve
: - motility / secretion

• parasympathetic: upper git ~> vagus
Lower git ~> pelvic
+ motility/ secretion

Question 3

How plexus are stimulated ( submucosal - myentric )

Answer 3

Submucosal by chemical substance ( food )
Myentric by the stretched wall due food in lumen

Question 4

How submucosal / myentric work ( reflex)

Answer 4

• submucosal works by local axon reflex
(Chemical ~> submucosal stimulated~> gland )

• myentric works by local axon reflex
( stretch ~> myentric stimulated ~> ms )

• ganglionic reflex
( submucosal stimulated~> collateral ganglia ( sympathetic ) ( out of git ) ~> both submucosal, myentric inhibited

• long ( central nervous) reflex
Receptore in gut stimulated ~> brain / spinal cord ~>preganglionic para ~> 2 plexus stimulated ~> ms / gland )

Receptore in gut stimulated ~> brain / spinal cord ~>postganglionic sympa ~> 2 plexus
~> ms / gland

Question 5

🛑Enumerate reflex GIT , examples

Answer 5

1- short local axon reflex
Eg : reflex gastrin secretion
2- ganglionic reflex
Eg : enterogastric , gastrocolic
3- long ( central nervous ) reflex
Eg : salivary secretion

Question 6

Parts of gland

Answer 6

1- acini
2- duct

Question 7

Acini types

Answer 7

1- serous cells that secrete saliva reach in amylase
2- mucus cells that secrete saliva reach in mucin

Question 8

Type of each gland / percentage of saliva released

Answer 8

1- parotid : serous / 20%
2- sub mandibler : seromucus / 70%

Question 9

Salivary secretion process ?

Answer 9

1- active process
2- 2 processes
• primary
In acini , it secretes primary sec. With amylase or mucin in solutions of ion in concentration near to that of plasma ( iso osmotic )

• secondary
In duct , modification occurs
- na is actively absorbed in exchange to k by aldosterone
- hco3 is actively secreted in exchange to cl
So it is hypo osmotic

Question 10

Talk about saliva

Answer 10

3
1- 1,5 litre / day
2- it is
• 99% water
• electrolytes
Na , cl in saliva 1/7 that of plasma
K in saliva is 7 times that of plasma
• organics : eg amylase

3- function
- lubrication
- digestive : salivary amylase digests COOKED starch
- oral hygiene :
the flow of saliva wash away food particles
Thiocynate destroy bacteria
Proteolytic enzymes eg lyzozomes
- excratory channel : eg urea
- heat loss : eg in panting animals
- solvent
- dilution medium for irritant substances

Question 11

Regulation

Answer 11

• it is done by
- superior salivary nuclei
- inferior salivary nuclei

• afferents may come from
- taste buds in tongue , mouth , pharnx ( unconditioned)
- impulses from higher centers : thinking , smelling ( conditioned)
- impulses from stomach eg GIT irritation

• efferents are para
S ~> facial
I ~> glossophargneal

Question 12

Para , sympa stimulation of salivary glands

Answer 12

Para
1- profuse large secretion of water with low enzymes
2- vD

Sympa
1- little secretion
2- VC
3- contraction of myoepithelial cells ~> + squeezing

Question 13

nervous control of salivary secretion occurs via two reflexes

Answer 13

Conditioned reflex
Unconditioned reflex

Question 14

Pavlov experiment

Answer 14

1- he proved that conditioned reflex is not inherent as they are acquired by training
2- using dog
3- special sound bell before eating
4- after several days , he found out that the sound is enough to produce saliva

Question 15

Talk about Chewing ?

Answer 15

1- breakdown of large food particles into small pieces
2- partly voluntary partly reflex
3- chewing reflex ( stretch reflex) :
Presence of food ~> drop of lower jaw~> stretch of jaw muscles ~> feedback contraction
4- function
1- Increasing the surface area of food particles
2- Removal of the indigestible cellulose
3- Making fod transport easier
4- Stimulates secretion of saliva

Question 16

Deglutition phases

Answer 16

1- buccal
2- pharyngeal
3- esophageal

Question 17

Talk about buccal phase

Answer 17

1- voluntary
2- the tongue is elevated upward backward against hard palate by contraction of mylohyoid muscle
3- mouth must be closed as swalling is difficult with open mouth eg dentist

Question 18

🛑Talk about pharngeal phase

Answer 18

1- involantary
2- As the bolus is pushed backwards, it stimulates receptors located at the pharyngeal opening especially in the tonsillar pillars , impulses are transported via afferent fibers of the 5th and 9th to the swallowing center in the medulla oblongata.

• protective reflexes
1- nose : by elevation of the soft palate closing the posterior nasal opening.
2- mouth :Elevation of the tongue against the palate.
Continued contraction of the mylohyoid muscles.

3-epiglottis closes closes superior laryngeal orifice.
2-Approximation of the vocal cords, this is also closes the glottis (more important).

3- Inhibition of respiration (deglutition apnea).

• pharngeal peristalsis
starts in the superior pharyngeal muscles and along the middle , inferior pharyngeal muscles to the esophagus

Question 19

Talk about esophageal phase

Answer 19

1- involantary
2- consists of 3 steps
•Relaxation of the upper esophageal sphincter.
It is normally closed to prevent passage of air
But open / relax while swallowing
• Traveling of bolus food along the esophagus..
•Esophageal peristalsis.is two types:-
Primary :Continuation of that of the pharynx.
Secondary : if primary peristalsis fails

Question 20

Git hormones

Answer 20

• secreted by APUD cells in mucosa
• 1 - gastrin family : gastrin, cck
  -2- secrtin family : secrtin, VIP , GIP

Question 21

Augmented salivary secretion ?

Answer 21

Sympa after para ~> + saliva ( para ~> + saliva
Sympa~> squeeze)

Question 22

Paralytic secretion explanation

Answer 22

cutting of chorda tympani

Observing
Low secretion
High amount of secretion
Contraction of myo ~> squeeze~> + secretion

This due to hypersensitivity of deinnervated gland to the circulating chemical transmitters
( وان اصلا ال sympa متقطعش ف العضلات بتنقبض عادي )