# data[].attributes.body
1. MCV is mean corpuscle volume. Determines the average size or volume of RBC. Normal value is 87. Normal MCV means the cells are normocytes.
MCHC measures average concentration of hemoglobin in RBCs.

2. Microcytic hypoblastic anemia

# data[].attributes.body
Afferent input comes from Cranial Nerve 2,9 that comes from tastebuds on ant and post tongue and CN5 from mechanorexeptors in oral mucosa and peridontal ligament then it will integrate into Nucleus Solitary tract and trigeminal nucleus respectively and it will react parasymphatetic reaction to sublingual and submandibular from facial nerve via submandibular ganglion. Parotid from glossopharyngeal via otic ganglion. These pathway regulate the fluid regulation by releasing AcH at the surface of salivary gland acinar cells. It will increase the volume and more mucous secretion on parasympathetic reaction. As for sympathetic reaction it will cause proteinaceous secretion as peptides without affect its volume where the symphathethic post ganglionic from cervical ganglion of symphathetic chain.

# data[].attributes.headline
Dr Ashok(factor regulating HCL Mechanism

# data[].attributes.subject
Dr Ashok(factor regulating HCL Mechanism

# data[].attributes.body
There are three factors that regulating the hvlcl mechanism which are vagus nerve, gastrin and ECL cells. The vagus nerve will direct the activation of parietal cells by releasing acetylcholine hormone. For indirect activation, it will release gastrin releasing peptide. In the parasympathetic system, the postganglion will be close to the organ and it releases the GRP to the blood circulation and lead to stimulation of parietal cells. The second factor is gastrin which is hormonal effector. This will cause distention of gastrin to the local stimulation and gives sensory to myenteric plexus to release acetylcholine and increase the g cell stimulation and more gastrin will release. Next, the pepsinogen will release pepsin to help in breakdown the protein into amino acid and it will then touch the g cells to release more gastrin. The third factor which is ECL cells that located close to parietal cells. It will release histamine to activate h2 receptor in parietal cells and increase the acid secretion

# data[].attributes.body
Phases of Gastric Secretion
There are 3 phases of gastric secretion which is cephalic, gastric and intestinal.
Cephalic phase- Activated by thought, taste, smell and sight of food and swallowing,mediated mostly by cholinergic/vagal mechanisms.
Gastric phase- Due to the chemicsl effects of food and distension of the stomach.Gastrin appears to be a major mediator since the response to food is largely inhibited by blocking gastrin action and its receptors.
Intestinal phase- Accounts for only small proportion of the acid secretory response to a meal.

# data[].attributes.body
1. Parietal cells secreted HCl which acidifies the gastric contents (pH 0.8). On stimulation of food, water in parietal cells break down to OH- and H+. H+-K+ ATPase secretes H+ into lumen in exchange with K+. K+ ions enters parietal cells via Na+-K+ ATPase present in the basolateral side. HCO3- frm OH- and CO2 using carbonic anhydrase. Cl- ion secreted into the parietal cells by exchanging HCO3-. This Cl- ion enter gastric lumen and reacts with H+ to form HCl
2. The factors tht regulate the gastric secretions are Vagus nerve, gastrin hornone and ECL cells. In the vagus nerve, it has a direct activation of parietal cells by releasing Ach f

# data[].attributes.body
- secreted H+ is derived from the breakdown of H2O into H+and OH
- this H+ is secreted into the stomach lumen by the H+ K+ ATpase (poton pump)
-the transported K+ then passively leaks back into the lumen
- with the aid of carbonic anhydrase the metabolic CO2 binds with H2O to give H2CO3
- H2CO3 dissociates into H+ and HCO3
- the generates H+ replaces the secreted H+
The OH_ is neutralised by combining with the H+ generated from H2CO3
- The HCO 3 moves into the plasma by the same Carrier which transports Cl inside the cell
- the diffused H andCl combine together in the gastric lumen to form HCL

# data[].attributes.body
Mechanism HCL
It happen in parietal cells that will acidifies the gastric content with the pH of 0.8 whereby the H+ concentration is 3mil times that of arterial blood. By the stimulation of food, the water in parietal cells breaks fown H and OH. In the means tkme the HKATpase secretes H into limen in exchange with K. The K ions will then enters the parietals cells via NaKATPase present in the basolateral sides makes the NaK leaked inside into the lumen of canaliculi. The HCO3 is then produces in the parietal cells from OH and CO2. Then the Cl ion ks secreted into parietals cells by exchanging HCO3. This Cl ipm enters gastric lumen and react with H to HCL.

# data[].attributes.body
1. When the parietal cells are stimulated co2 and h20 will combine to form h2co3 which will split to form hydrogen ions and bicarbonate ions in the presence of carbonic anhydrase, The hydrogen ions are then pumped to the lumen with the help of the hydrogen potassium pump. The bicarbonate ions then leave the parietal cell via an antiport of parietal cells and chloride ions enter. In the lumen hydrogen ions then combine with chloride ions to form the acid.

2. The regulation of HCl secretion involves the vagus nerve, gastrin, and the ECL cells. Vagus nerve is a neural effector. The two types of activation on the vagus nerve are direct and indirect activation. The direct activation of vagus nerve is by releasing the acetylcholine while the indirect activation is by releasing the GRP. Gastrin is the hormonal effector. It's secretion will activate the ECL cells. The ECL cells will release the histamine which then activates the H2 receptor(parietal cells) which will increase the HCl secretion.

3.

# data[].attributes.body
1. Structure of salivary secretion
Acinus - initial secretary process
Intercalated duct- initial portion of duct
Striated duct- modification of secretory product
Myoepithelial cells

2.*Mechanism of normal salivary secretion*
Primary secretion of saliva
- involves acini
- the acinar cells of salivary glands secrete initial saliva into salivary duct
- secretion contains pytalin, mucus and extracellular fluid.
- concentrations of primary secretions in initial saliva is isotonic to plasma
- electrolyte components of primary secretion includes Na+, K+, HCO3-, Cl-, H2O
- all the 3 ions are transported via sodium chloride potassium co - transporter

In the second stage, the primary saliva will be enhance a modification throughout the ductal tree. This indicated the reabsorption of NaCl and secreting HCO3. The ductal epithelium are usually poor permeable to water molecules. This will produce the final saliva which is in hypotonic condition.

1. When the taste bud is activated, the central nerves CN 7 and CN 9 are activated. This makes them to carried the impulse to the nucleus tractus solitarius, then all the way goes to the trigeminal. This is the mechanoreceptors of afferent and efferent impulses. Then they will convery to the superior and inferior salivatory nuclei to produce saliva.

2. Salivary secretion is mainly controlled by parasympathetic system

- vasodilation of blood capillary

- high concentration of electrolytes present

- high concentration of sodium ions

- high amount of water enters the cell

- causes watery secretion

- aldosterone is not secreted in parasympathetic so does not cause more absorption of sodium ions

3. Sympathetic stimulation will lead to vasoconstriction in the blood vessels which will lead to decrease in the blood flow which lead to decrees in the blood flow which lead to low filtering which will lead to decrease in the electrolytes and decrease in H20 so there will he low water. The protenious secretion aldosterone also will be secretary which will lead to increase in the Na reabsorption which will to water reabsorption also

Case 2

Cephalic phase

- taste, smell and thought of food/ sensations of food in mouth stimulates the medulla oblongata

- vagus nerve carry parasympathetic actioon potentials to the stomach, where enteric plexus neurons are activated

- postganglionic neurons stimulate secretion by parietal and chief cells and stimulate gastrin and histamine secretion by endocrune cells

- gastrin is carried through the circulation back to the stomach

Gastric phase

- action potential is generated by the mechanoreceptor. Carried by vagus nerves to medulla oblongata

- stimulate gastrin and histamine secretion

- activates local reflexes that increase stomach secretion

- gastrin is carried back to stomach

Intestinal phase

- nervous mechanicm

- hormonal mechanism

2. Factors that regulates the HCL secretion are composed of three part, which are :

1. vagus nerve

-it is divided into direct activation by releasing Ach and indirect activation by releasing GRP

2. gastrin

-act as a hormonal effector

3. histamine

-increases acid secretion

3. Water in parietal cell will breakdown into H and OH where the H and K ATPase which is secrete H into the lumen in the exchanges with K. The K ions will enter parietal cell via Na , K ATPase present in the Basolateral  side. HCO3 is produced in the parietal cells from OH and CO2 with help on carbonic anhydrase. The Cl ions is secreted into the parietal cells by exchanging HCO3 , this the CL will enters gastric lumen and react with H to from Hydrochloric acid

1. MCV is mean corpuscle volume. Determines the average size or volume of RBC. Normal value is 87. Normal MCV means the cells are normocytes. Low MCV determines microcytic anaemia. High MCV determines macrocytic anaemia.
MCHC measures average concentration of hemoglobin in RBCs.

2. Microcytic anaemia

# data[].attributes.headline
Dr Ashok - Afferent and Efferent Pathway Reg of Salivary Secretion 

# data[].attributes.subject
Dr Ashok - Afferent and Efferent Pathway Reg of Salivary Secretion 

# data[].attributes.body
Afferent input comes from Cranial Nerve 2,9 that comes from tastebuds on ant and post tongue and CN5 from mechanorexeptors in oral mucosa and peridontal ligament then it will integrate into Nucleus Solitary tract and trigeminal nucleus respectively and it will react parasymphatetic reaction to sublingual and submandibular from facial nerve via submandibular ganglion. Parotid from glossopharyngeal via otic ganglion. These pathway regulate the fluid regulation by releasing AcH at the surface of salivary gland acinar cells. It will increase the volume and more mucous secretion on parasympathetic reaction. As for sympathetic reaction it will cause proteinaceous secretion as peptides without affect its volume where the symphathethic post ganglionic from cervical ganglion of symphathetic chain.

# data[].attributes.body
Case study 1.
A. Structure of saliva
1.salivon is the basic unit consists of acinus, intercalated disc and striated duct.acinus is involve in initial secretory process,intercalated disc is the intial portion of duct and striated duct is the modification of secretory product.
B. Mechanism of formation of saliva
1. Primary secretion of salive. The acinar cells of salivary glands secrete the initial  saliva into the salivary duct.
Initial salive state is isotonic (Na+, Cl-, K+,HCO3 has same conc. As plasma)
2. Modification of saliva
The ductal cells change the composition con. Of the saliva by
- Reabsorption of Na+ and Cl- in ductal cells (conc. Of ions lower than plasma)
-Secretion of K+ and HCO3  caused by the ductal cells. (Conc. Ions higher than their plasma con.)
= The Na+ and Cl- are exchange with K+ and Hco3 respectively
=Modified saliva becomes hypotonic

CASE STUDY 3
A.
B.Mechanism of HCL secretion:

On stimulation by food,
- Water in parietal cells break down to H+ & OH-
- H+-K+ ATPase secretes H+ into lumen in exchange with K+
- K+ ions enters parietal cells via Na+-K+ ATPase present in the basolateral side
- HCO3- is produced in parietal cells from OH- & CO2 (carbonic anhydrase)
-Cl- is secreted into parietal cells by exchanging HCO3-
- This Cl- ion enters gastric lumen and reacts with H+ to HCl (hydrochloric acid)
C. PHASES OF GASTRIC
1. Cephalic phase
- Sense of taste, smell and thought of food stimulate medulla oblongata.
- vagus nerves carry parasympathetic ap to the stomach (enteric plexus neurons activated)
- postglanglionic neurons stimulate secretion of gastrin and histamine by parietal and chief cells.
- gastrin is carried through the  circulation back to the stomach. (Stimulates more secretion)

Gastric phase
-distention of stomach stimulates mechanoreceptors in the stomach which activate parasympathetic reflex. (Action potential carried by vagus nerves to the medulla oblongata)
- medulla oblongata increases action potential which stimulate more secretion of gastrin and histamine.
- distention of stomach activate local reflex that increase stomach secretion.
- gastrin and histamine carried through circulation and back to stomach to stimulate secretion.

Intestinal phase
- chyme (ph2) present in duodenum inhibits gastric secretion.
- chemoreceptor in duodenum stimulated by h+ and lipid. Action potential is generated and carried by vagus nerve to medulla oblongata where they inhihit parasympathetic action potential, hence gastric secretion is decreased.
- local reflexes activated by h+ or lipids also inhibit gastric secretion.
- secretin and cck decrease  gastric secretion as well

# data[].attributes.body
1. Structures needed for salivary secretion
Acinus, intercatalated duct, striated duct, myoepithelial cells

2. There are 2 stages of the mechanism of normal salivary secretion. The primary secretion involves the acini tht contains the ptylin, mucus and extracellular fluid. Primary secretion fluid is isotonic with plasma.

The second stage involves the salivary duct whereby the secretion is actively reabsorbed of its Na exchange with K. HCO3 secreted into the lumen by ductal epithelial, while chloride goes the opposite way by passive exchange. Saliva becomes hypotonic as ductal epithelium is impermeable to water

# data[].attributes.body
Mechanism of normal salivary secretion

Salivary secretion has two stages. Firstly, it’s primary secretion stage involve acini.Isotonic Primary secretion consist of ptyalin, mucus and extra cellular secretion. In this stage, maximal salivation will occur where it increase by 20 folds where more secretion happen but less time given for the ionic exchange. So it will be less hypotonic and more isotonic. The second stage involves the salivary duct. Where it involve in isotonic solution That consist Sodium active absorption ,chloride passive absorption flows in opposite way by passive exchange , potassium active secretion and bicarbonate ion secretions secreted into lumen by dicta epithelial. Then total saliva is secreted to become hypotonic when the du tak epithelium impermeable to the water.

# data[].attributes.body
Structures needed for salivary secretion is secretory unit which is called salivon.
1.The basic units of salivon consists of acinus (initial secretory process), intercalated duct (initial portion of duct), striated duct (modification of secretory product), myoepithelial cells (surrounded acinus and intercalated duct, contraction moves saliva forward)

2. The mechanism of salivary secretion involve 2 stages. The primary secretion stage involved the acini while the secondary stage  involved the salivary duct. The primary secretion contains ptyalin, mucus and extracellular fluid. The primary secretion fluid is isotonic with plasma. In the secondary mechanism, in the salivary duct, the secretion fluid is actively reabsorbed of it's sodium, exchanged with potassium. Bicarbonate ion secreted into lumen by ductal epithelial, while chloride goes the opposite way by passive exchange. Saliva becomes hypotonic as ductal epithelium is impermeable to water.

3. The CNVII and CNIX will carry the afferent signal from tastebuds on anterior and posterior of the tongue to the nucleus tractus solitarius. On the other hand, the CNV carry the afferent signal from mechanoreceptor in oral mucosa and periodontal ligament to the trigeminal nucleus. Both nucleuses in the medulla oblongata will send efferent signals to submandibular ganglion and otic ganglion. The submandibular ganglion will then transmit efferent signals to sublingual and submandibular gland. The otic ganglion will transmit efferent signal to parotid gland. The sympathetic pathway starts from CNS T1-T3/T4 which transmits signal to sympathetic ganglia, including superior cervical ganglion. It will transmit signal to submandibular gland and parotid gland.

4.

# data[].attributes.body
1. Structure of salivary secretion
Acinus - initial secretary process
Intercalated duct- initial portion of duct
Striated duct- modification of secretory product
Myoepithelial cells

# data[].attributes.body
1. The basic unit salivon consist of acinus which is the initial secretory process and intercalated duct that is the initial portion of the duct. It also has striated duct which is a modification of secretory product and myoepithelial cells that surround the acinus and intercalated duct.
2. The primary secretion stage involves the acini wherea the secondary stage involves the salivary duct. The primary secretion involves water and electrolytes components. water and Na+ travel together into lumen through paracellular transport. Na+, Cl- and K+ Enter lumen via symporter while Na+-K+ pump exchange both Na+ and K+ Ions in opposite direction. Primary secretion fluid is isotonic with plasma. Secondary secretion occur at salivary duct which involved Na+-K+ pump that actively exchange both Na+ and K+ ions. HCO3 is secreted into lumen while Cl- secreted out from lumen by passive exchange. Saliva become
hypotonic as it enter ductal epithelium.

3. MECHANISM OF HCL SECRETION
in parietal cell, water will be breakdown inti hydrogen and hydroxide ion. Hydrogen ion will be secrete to len of canaliculi by h+K+ atpase in exchange with K.
Co2 diffuse into parietal cell and combine with hydroxide ion to form bicarbonate ion.
Bicarbonate ion will exchange with chloride ion, cl- in, hco3- out.
Chloride ion, that enter just now, entering gastric lumen and react with hydrogen ion, to form HCL

# data[].attributes.body
The structure of salivon which is a basic unit of salivary glands is composed of the acinus which is the initial secretory process, intercalated duct which is the initial portion of duct, striated duct where the primary secretory product is modified and myoepithelial cells which causes contraction to move saliva forward and prevent any backflow. Acinus and intercalated duct are surrounded by myoepithelial cells.

# data[].attributes.body
1. The basic unit - salivon which consists  of  Acinus ( initial secretory process) , Intercalated duct, Striated duct, myoepithelial cell

2. 1st stage - primary secretion stage which involves the acini. It contains ptylin, mucus and extracellular fluid. The fluid is isotonic with plasma. The electrolyte component of primary secretion consists  of Na, K, HCO3, Cl and H20.

2nd stage - Salivary duct secretion. In the salivary duct, there’s active reabsorption of Na exchange with K thru sodium potassium ATPase.  The HC03 secreted into lumen by ductal epithelial, Cl goes opposite way by passive exchange.

3. Afferent input, originates from the tastebuds are carried thru CN7, CN9, meets at the medulla ( NST) , which later innervates Otic Ganglion thru Glossopharyngeal nerve for impulse to be reached to the parotid gland.

# data[].attributes.body
Structure needed for salivary secretion is
- acinus which intial secretory process.
- intercalated duct which is the initial portion of duct.
- striated duct for modification of secretory product.
- myoepithelial cells which surround acinus and intercalated duct
2. Mechanism of normal salivary secretion.

2 stages :
- primary secretion stage involves the acini. Contains ptyalin, mucus and extracellular fluid.
- primary secretion fluid is isotonic with plasma
- second stage involves the salivary duct
- in salivary duct, the secretion duct, the secretion fluid is actively reabsorbed of its Na, exchanged with K
- HCO3 secreted into the lumen by ductal epithelial, while Cl goes the opposite way by passive exchange
- saliva becomes hypotonic as ductal epithelium is impermeable to water
- at maximal salivation, primary secretion increases by 20
folds, as the rate of secretion increases, less time for ionic exchange to happen
- thus, NaCl concentration increases about 1/2 to 2/3 of
plasma but still remains hypotonic compared to  plasma

# data[].attributes.body
Structure of salivary secretion
- Secretory Unit call salivon that consist acinus as initial secretory process, intercalated duct as initial portion of duct, stuated duct as modification of secretory product, myoepithelial cells that surround acinus and intercalated duct plus it helps in the contraction to moves saliva, prevents development of back pressure