2. " "
Accessory organs to the digestive
system
The salivary glands : are ductal glands in mammals
that secrete saliva. They are solid formations made up of
millions of secretory cells. Thin channels flow between
these cells that collect and carry saliva and direct it to a
single channel that in turn carries saliva into the mouth
.
1-The parotid glands are the largest salivary glands, and
they are located on the side of the lower jaw in front of
the ear
.
2-The sublingual or lingual glands are the smallest
salivary glands and are found under the tongue. What
distinguishes them from other salivary glands is that
instead of having a single large duct such as the parotid
and submandibular glands, it has an entire row of much
smaller ducts that open in the mouth along the
transverse edge. Minor located in the floor of the mouth
under the tongue.
3-submandibular glands, they are located below the
base of the tongue, and each submandibular gland has a
channel that extends forward, penetrating the tissues at
3. the bottom of the mouth and opening through an
opening that can be seen easily at the base of the small
limb of the tongue.
?
Q/What is the function of the salivary glands
The salivary glands secrete saliva, which has many
benefits for the oral cavity and its overall health. These
benefits include:
Protection
Saliva is made up of proteins that lubricate and protect
the soft and hard tissues of the oral cavity.
Caching
In general the higher the saliva flow rate, the faster the
clearance and the greater the buffer capacity, thus
better protection from tooth decay is provided.
Therefore, people who have a slower rate of salivation
4. along with a lower ability to buffer, reduce the
protection of saliva against microbes.
Membrane formation
Saliva forms a thin film on the surface of a tooth. The
membrane contains mucus and glycoprotein rich in
proline from saliva. The proteins (ethestrin and proline-
rich proteins) within the salivary glutes prevent
demineralization and encourage remineralization by
attracting calcium ions.
Maintaining healthy teeth
Demineralization occurs when enamel degrades due to
the presence of acid. When this happens, the effect of
the buffering ability of saliva (increases the rate of saliva
flow) prevents demineralization. Saliva can then begin
to promote tooth remineralization by hardening the
enamel with calcium minerals and phosphates.
Antimicrobial
Depending on the elements it contains, saliva can inhibit
microbial growth. For example, lactoferrin in saliva
naturally binds to iron. Since iron is a major component
of bacterial cell walls, iron removal breaks down the cell
5. wall which in turn breaks down the bacteria.
Antimicrobial peptides inhibit the growth of Candida
albicans and streptococcus. Salivary immune globulin A
collects oral bacteria and prevents dental plaque from
forming.
Tissue repair
Saliva can encourage soft tissue repair by reducing
clotting time and increasing wound shrinkage.
digestion
Saliva contains the enzyme amylase, which breaks down
starch into maltose and dextrin. As a result, saliva allows
digestion before food reaches the stomach.
Tasting
Saliva acts as a solvent in which solid particles can
dissolve and enter the taste buds through the oral
mucosa on the tongue. These taste buds are found
within the synthesized loops, where small salivary
glands secrete saliva.
6. The liver :an organ found only in vertebrates,
detoxifies various metabolites, synthesizes proteins, and
produces biochemicals needed for digestion. In humans,
the liver is located in the upper right quadrant of the
abdomen, below the diaphragm. Other roles in
metabolism include: regulation of glycogen storage, the
breakdown of red blood cells, and hormone production.
The liver is an attached digestive gland that produces
bile (an alkaline compound that helps break down fats).
Bile aids digestion by emulsifying fats. The bile produced
by the liver is stored in the gallbladder - a small sac that
lies under the liver - and then it travels to the small
intestine to complete the digestive process.
Functional anatom:
Liver hilum, which is the yellow circle par
1-The central area, or hilum of the liver, includes the
area known as the porta hepatis, which consists of: the
common bile duct, the common hepatic artery, and the
portal vein. The duct, vein, and artery divide into left
and right branches, and the hepatic regions fed by these
branches form the left and right functional lobes
.
2-The functional lobes are separated by an imaginary
plane (the Cantele line, which extends from the
7. gallbladder fossa to the inferior vena cava) into true
right and left lobes.
3-The liver is also divided into left and right lobes by the
middle hepatic vein.
4-The right lobe is divided into an anterior segment and
a posterior segment by the right hepatic vein
5-The left lobe is divided into medial and lateral
segments by the left hepatic vein
The gallbladder: in vertebrates, is a small, hollow
organ in which bile is stored and concentrated before it
is released into the small intestine. In humans, the
gallbladder piriformis is located below the liver,
although the structure and location of the gallbladder
may differ greatly between animal species. The
gallbladder receives and stores bile produced from the
common hepatic duct, then releases it through the
common bile duct towards the duodenum, where the
juice works to aid in the digestion of fats.
Microscopic anatomy:
Micrograph of normal gallbladder wall, stain H&E
The gallbladder wall consists of a number of layers,
where the inner surface of the gallbladder wall is lined
by a single layer of columnar cells with a brushy edge of
8. the microvilli, much like intestinal absorptive cells.
Below the epithelium lies the lamina propria, the
muscular layer, the outer layer around the muscle and
the serous membrane. Unlike all other places in the
intestinal tract, the gallbladder does not contain a
mucosal muscle plate, and muscle fibers are not
arranged in distinct layers
.
The mucosa is the inner part of the gallbladder wall,
where it consists of a single layer of cephalic cells, with
cells that have small hair-like attachments called
microvilli, which are located on a thin layer of
connective tissue called the lamina propria. The mucosa
contracts and collects in small external pockets called
rugae.
The muscle layer is located below the mucosa, where it
is made up of a smooth muscle with fibers that run
longitudinally, obliquely and transversely, and are not
arranged in separate layers. The function of muscle
fibers is to contract to remove bile from the gallbladder.
The gallbladder contains Rokitansky-Aschov pockets,
which are a distinctive feature of it, which are external
pockets of the mucous membrane, and may extend into
the muscle layer, indicating the occurrence of adenoma.
9. The muscle layer is surrounded by a layer of connective
and fatty tissue
.
The outer layer of the bottom of the gallbladder, and
the surfaces not in contact with the liver, are covered by
a thick serous membrane, which faces the abdominal
serous membrane. The serous membrane contains
blood and lymph vessels. Connective tissue covers the
surfaces that come into contact with the liver.
Q/What are the functions of the gallbladder?
1-The storage of bile is the primary function of the
gallbladder, as it is used to digest fats from food. Juice is
produced in the liver, then it flows through small vessels
into large liver ducts, and eventually it flows through the
gallbladder duct (part of the bile tree) to reach the
gallbladder, where it is stored. At any given time, 30 to
60 milliliters (1.0 to 2.0 fluid ounces) of juice are stored
in the gallbladder.
2-The liver also produces bile, which is stored in the
gallbladder, and it differs from the bile secreted by the
gallbladder. During the gallbladder storing the bile, it is
concentrated 3-10 times by removing some water and
electrolytes, as this process takes place through the
active transport of sodium and chlorine ions through the
epithelium of the gallbladder, which creates an osmotic
10. pressure that leads to the reabsorption of water and
other electrolytes.
The pancreas: or pancreatic organ, or complicated or
sweet, is one of the most important glands in the body
of mammals and has a dual role:
1-Exocrine gland: It secretes pancreatic juice containing
digestive enzymes.
2- An endocrine gland, or endocrine gland, is based on
the secretion of a number of hormones, the most
important of which is insulin, which is secreted by the
Langerhans Islands and which acts to represent sugar
and carbohydrates. Its imbalance mainly leads to
diabetes, for example.
Anatomy of pancreas:
The colostrum is a soft, lobular gland that lies on the
posterior abdominal wall and extends transversely in
the abdomen from the duodenal curve to the navel of
the spleen, behind the stomach. They are about 13 cm
long, 2-7 cm wide, and weigh 70-80 g. It is located at the
level of the first lumbar vertebra, just below the celiac
trunk. The transverse colon mesentery is attached to it,
separating the supraclone and hypochondral space.
11. 1.The bile ducts: 2. Intrahepatic bile ducts, 3. Right and
left hepatic ducts, 4. The common hepatic duct, 5. The
gallbladder duct, 6. The common bile duct, 7. The
ampulla of Vater, 8. The large duodenal papilla
9.Gallbladder, 10--11. The left and right lobes of the
liver. 12. The spleen
13.The esophagus. 14. The stomach. 15. The pancreas:
16. The extra pancreatic duct, 17. The pancreatic duct
18.Small intestine: 19. Duodenum, 20. The jejunum
21—22.Right and left kidneys