Download Digestion in oral cavity and stomach

yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project

Document related concepts

Hydrochloric acid wikipedia , lookup

Adjustable gastric band wikipedia , lookup

Pancreas wikipedia , lookup

Bariatric surgery wikipedia , lookup

Saliva testing wikipedia , lookup

Common characteristic of the mouth cavity digestion
 In the oral cavity take place such main processes:
 1. Primary analyses of substances, which are
coming to organism – taste analyzes;
 2. Reflector signals from receptor, which are
present in these area to the another organs of
digestive system, to the central nerve system –
medulla oblongata, stomach, small intestine,
 3. Chemical processing of food;
 4. Mechanical processing of food;
 5. Absorption of some substances.
 Chewing of food is important, because
fruits and vegetables have cellulose
which must be broken before the food
can be utilized. In the mouth cavity
begin digestion of carbohydrates, which
help to the functional activity of
 When our food are in the mouth stimulate
the receptors of oral cavity; from which
impulses go to the different part of brain
and return to different part of digestion tract
– stomach, small intestine, pancreas, in
which secreted juices with enzymes
 In the mouth cavity open three pair of big
salivary glands and a lot of small buccal
glands. Submandibular and sublingual
glands consist of the cells of serum and
mucous types and secrete serous and mucus
types of saliva. Parotid glands consist of the
serum types cells and secrete serous type of
 Small buccal glands consist of mucous
types of cells; produce mucous saliva with a
big quantity of water. Saliva necessary for
our digestion. In a mouth chewing a food by
teeth and lingual. In the mouth cavity begin
digestion of carbohydrates by alfa-amilase –
ptyalin. To secrete different types of saliva
for digestion processes – with a big quantity
of water or organic and inorganic
Quantity, composition and properties of
 Quantity, composition and properties of saliva (In
the case of dream produce nearly 0,05 mL/minute,
in the normal condition – 0,5 mL/minute, in the
case of maximal secretion – near 5 mL/minute. By
day produce 0,8-1,5 L of saliva. Composition of
saliva: water, organic – alfa-amilase, lipase,
phosphatase, RNAase, DNAase, mucin,
substances for protective – lisocim, thiocianates,
antibodies – and unorganic substances – sodium,
potassium, calcium, chlorites, etc.
Mechanism of saliva forming
 In acinars' cells produce primary saliva in which
synthesis necessary amino acids, glucose, mineral
substances (for example, Ca++). In the cells of
salivary glands occur passive processes, which
provide moving of water and electrolits from
blood to the glands’ ductus (strait). In the ductus
occur reabsorption of sodium, chlorine, secretion
of potassium, HCO3–. This is the secondary saliva.
Aldosterone increase reabsorption of sodium and
secretion of potassium.
Role of saliva in vitality of
 1. Moisten of solid food;
 2. Dissolving of substances;
 3. Moisten of mouth;
 4. Cover food;
 5. To help of swallowing;
 6. Primary hydrolyzing of carbohydrates;
 7. Antibacterial properties;
 8. Neutralized the stomach juice.
Mechanism of saliva formation
Formation of saliva
 Conditional reactions caused by appearance
of food, it smell and other stimulus, which
are connect with food.
 Unconditional influences have parasympathetic and
sympathetic components. Parasympathetic
components beginning from receptors of tongue
and oral cavity. From its impulses pass through the
fibers of n. trigeminus, n. facialis, n. vagus, n.
glossopharyngeus, to the center of salivation.
Impulses return to saliva glands by n. facialis, n.
glossopharyngeus. Sympathetic components of
unconditional influences beginning from side cornu
of upper thoracic segments of spinal cord – Th2-Th4. Then impulses go to saliva glands through the
upper cervix sympathetic ganglion. The cortex of
big hemispheres, hypothalamus, lymbic system
regulate the salivation through these nerves.
Conditional signals, emotions may inhibit
Influence of vegetative nerves on secretor
activity of salivary glands
 Stimulation of the parasympathetic nerve
supply causes profuse secretion of watery
saliva with a relatively low content of
organic material. Stimulation of the
sympathetic nerve supply causes profuse
secretion of saliva with small quantity of
water with a relatively big content of
organic material.
 Mediator of parasympathetic nerve system –
acetylcholine – stimulate M-cholinoreceptors of
baso-lateral membrane and activate entrance of
Ca2+ and activate kalmodulin. These reaction
caused production of a big quantity of saliva with
low quantity of organic substances. Mediator of
sympathetic nerve system – norepinephrine –
membrane, activated adenilatcyclase that form
cAMP. These reaction caused production of a
small quantity of saliva which have a big quantity
of organic substances.
Functions of stomach
 1. Digestive (mechanical treatment,
absorption, evacuation, secretion, depo);
 2. Excretor;
 3. Incretor.
Secretor activity of stomach
 Production of stomach juice per day – near
2,5 L of juice. Their main components –
enzymes, HCl and mucin. pH of morning
saliva is neutral, after eating – sour – 0,81,5.
Composition of stomach juice and their properties
 There are 2 types of glands – the oxyntic (or
gastric) and the pyloric glands. The oxyntic glands
secrete hydrochloric acid, pepsinogen, intrinsic
factor, and mucus. The pyloric glands secrete
mainly mucus. The main cells (peptic or chief
cells) produce non active enzymes (pepsinogens).
There are 7 pepsinogens. They hydrolyzed
 Optimum pH of its activity is 1,5-2,0. Pepsinogens
whose activity the most in the condition of pH 3,23,5 is gastrecsin. In the stomach juice produces
lipase and gelatinese. HCl produce in parietal or
oxyntic cells. pH of it secrete is near 0,8. These
processes need energy of lipids. Mechanism of it
production: Cl- activly transported in the
canaliculi, Na+ – from the canal into cytoplasm.
H2O dissopciated to H+ and OH-. H+ activly go
into canaliculi in change of K+. In these processes
take plase Na+,K+-ATPase. CO2, which produce in
cells act with H+ and syntheses HCO-. This anion
go into the cell in change by Cl-.
Formation of hydrochloric acid
Parietal cell
Role of the hydrochloric acid in the
 1. To promote the swell of protein;
 2. To promote the change of pepsinogen in
 3. To make optimal conditions for actions of
 4. To fulfill protective role from bacteria;
 5. To promote motor and evacuated
functions of stomach;
 6. To stimulate production of duodinum
gormon – secretin.
Phases of stomach secretion
 Cephalic phase is caused by nervous system. It has
Conditional reactions caused by appearance of
food, it smell and other stimulus, which are
connect with food. Unconditional influences is
parasympathetic and beginning from receptors of
tongue and other receptors of the oral cavity. From
these receptors impulses pass through the fibers of
n. trigeminus, n. facialis, n. glossopharyngeus, n.
vagus to the medulla oblongata. Impulses return to
stomach by n. vagus. Except neuron influences
this phase has humoral influences – brunch of n.
vagus produce gormon gastrin. These phase is
very short.
Value of gastric juice secretion
In norm gastric juice secretion must be
to 3,5
Production of common 10-35
HCl, mmol/L
Production of free HCl, 0-20
Debit of common HCl, to 1,5
Debit of free HCl, to 1
Phases of stomach secretion
 Stomach phase is depends on the quantity of food,
which are present in stomach. It has vago-vagal
reflexes (by mean of central nerves system) and
local – peripheral reflexes, which are closed in
stomach walls. Duration of these phase is longer
and quantity of juice is much. It has humoral
mechanisms too (production of gastrin and
 Intestine phase: presence of food in the upper
portion of small intestine can cause the stomach to
secrete small amount of gastric juice. This
probably results of gastrin are also released by the
duodenal mucosa in response to distension or
chemical stimuli of the same type as those that
stimulate the stomach gastrin mechanism.