Description

This video covers the anatomy of the bile pathway, gall bladder, and pancreas.

Function of Bile:

• Bile contains 97% water, less than 1% bile salts, bilirubin, and fats.
• Emulsification of fats.

Bile Pathway:

• Bile is produced by the liver.
• Biliary Ducts:
  • Right Hepatic Duct (Ductus Hepaticus Dexter)
  • Left Hepatic Duct (Ductus Hepaticus Sinister)
  • Common Hepatic Duct (Ductus Hepaticus Communis)
• Gall Bladder (Vesica Biliaris)
• Cystic Duct (Ductus Cysticus)
• Bile Duct (Ductus Choledochus) – 7 cm long
• Pancreatic Duct (Ductus Pancreaticus)
• Hepatopancreatic Ampulla (Ampulla Hepatopancreatica)
• Major Duodenal Papilla (Papilla Duodeni Major)
• Hepatopancreatic Sphincter (Sphincter Ampullae Hepatopancreatica) – also known as the Sphincter of Oddi

Gall Bladder:

• Fossa for the Gall Bladder (Fossa Vesicae Biliaris)
• Fundus of the Gall Bladder (Fundus Vesicae Biliaris)
• Body of the Gall Bladder (Corpus Vesicae Biliaris)
• Neck of the Gall Bladder (Collum Vesicae Biliaris)

Wall of the Gall Bladder:

• Tunica Mucosa:
  • Mucosal Folds of the Gall Bladder (Plicae Tunicae Mucosa Vesicae Biliaris)
  • Spiral Folds (Plica Spiralis)
  • Mucosal Glands (Glandulae Mucosae)
• Tunica Muscularis:
  • Circular Muscle Fibers (Stratum Circulare)
• Tunica Adventitia
• Tunica Serosa (Part of the Hepatoduodenal Ligament)

Pancreas:

• 14-18 cm long, 2-3 cm wide, weighing 60-100 grams.

Functions of the Pancreas:

• Exocrine Function: Produces pancreatic juice (Succus Pancreaticus) containing digestive enzymes and bicarbonate.
• Endocrine Function: Releases hormones directly into the bloodstream, including insulin and glucagon.

Parts of the Pancreas:

• Head of the Pancreas (Caput Pancreatis)
• Body of the Pancreas (Corpus Pancreatis)
• Tail of the Pancreas (Cauda Pancreatis)

Topography of the Pancreas:

• Skeletopy: L1-L2
• Holotopy: Epigastric Region, Left Hypochondriac Region

Pancreatic Duct System:

• Main Pancreatic Duct (Ductus Pancreaticus)
• Accessory Pancreatic Duct (Ductus Pancreaticus Accessorius)
• Major Duodenal Papilla (Papilla Duodeni Major)
• Minor Duodenal Papilla (Papilla Duodeni Minor)

Transcript

Introduction
0:03
What’s up. Meditay here, and in this video, we’re gonna go through the anatomy of the Gallbladder,
0:08
Bile Pathway, and the Pancreas. Which are organs we call accessory organs.
0:12
Accessory organs are not a part of the digestive tract, but they have
0:16
an essential role in the actual digestion. That’s why they’re called accessory organs.
0:21
So, In this video, We’re first going to go through the Bile pathway, as you see here.
0:25
We’re gonna cover the Parts of the bile pathway, what the function of Bile essentially is,
0:30
and the layers of the bile duct. After that, we’ll go through the anatomy of the Gallbladder,
0:35
this one. Basically, talk through the different parts of it, its layers, and coverings. And then,
0:41
we’ll go through the anatomy of the pancreas, basically talk about its function, its topography,
0:45
and structures associated with it. Cool. So let’s start with the Bile pathway first.
Function of Bile
0:51
Let’s now start by looking at an anterior view of the bile pathway. And then tilt our model a
0:56
little bit, so we see the entrance into the Liver. So what we see now is the Liver, gall bladder,
1:03
pancreas, and a perfectly drawn duodenum going around the pancreatic head as you see here.
1:09
So the Bile Pathways is shown here, and let’s now follow the Bile from beginning to end to really
1:15
see what’s going on. It all starts up here, at the Liver, because and the Liver produces the Bile.
1:21
Now I’m not gonna go in too much detail into the physiology of Bile since I wanna
1:24
focus on anatomy for now, but the Bile contains roughly around 97% water and under 1% bile salts,
1:32
and some slight percent of bilirubin and fats. Bile salts are essential in digestion of fats,
1:38
or lipids, because they help diluting the lipid in water through the process of Emulsification.
1:45
And I’ll spend a quick minute explaining this mechanism to you before we continue because
1:49
you need to understand what you’re studying. So when you eat, your body separates the food
1:54
into Proteins, Lipids and Carbs. And they’re separated this way
1:59
because your body handles them differently. Lipid Metabolism, is an extremely interesting
2:04
pathway. Becasue when we talk about Lipids, The big component that we are going to be,
2:08
you know, consuming, in certain types of foods, is triglycerides.
2:13
Other things that we are going to consume that is consistent with the Lipid category
2:17
are Cholesterol, and phospholipids certain types of foods contain phospholipids. But of the most
2:20
significant here in caps are going to be the Triglycerides, so we’ll stick with this example.
2:25
Triglyserides are categorized as what we call Polymers, which takes a large amount of time for
2:31
our cells to absorb. In our digestive tract, we got these monster enzymes called Lipases,
2:37
which eat its way through the polymers, to break them down into their Monomers. In this case,
2:42
Triglycerides will become Free Fatty Acids and Glycerol. And these monomers are much
2:47
easier to absorb through our intestines. So where do Bile come in in all of this?
2:52
Well, this process requires the environment to be watery in order for the lipase to work,
2:58
so the lipids have to be diluted in water. Fat likes to stay close to eachother,
3:02
they’re hydrophobic. So what they’e gonna do is they’re gonna form this lipid globule.
3:09
And now the problem is that the lipid is not gonna be diluted in water anymore,
3:13
they’re just gonna float around in their own environment. And the poor monster lipase
3:17
doesn’t have nough surface area on the lipid globule to chew on. So the process of breaking
3:23
down lipids becomes very slow and inefficient. This is finally where Bile comes in. The Bile
3:29
salts will form a layer around the lipid globule. Dilute them into the water, where
3:34
our lipase can snack its way though and separate all the lipids apart much more efficiently.
3:40
This process is called emulsification. and that is the reason why Bile is essential
3:45
in the digestion of fat. So that was a simplified quick scheme. Now let’s continue with the anatomy.
Bile Pathway
3:51
Bile will go down through the Left Hepatic Duct, and the Right hepatic duct. The right
3:55
and left hepatic ducts will eventually unite in the middle and form the common hepatic duct.
4:01
The common hepatic duct is about 5 centimeters long and goes out through the Porta hepatis,
4:06
or the transverse groove, protected by the hepatoduodenal ligament.
4:10
Now the gall bladder is here, and it contains a lot of Bile. The gall bladder is a bladder that
4:15
stores Bile. So when you’ve eaten, Bile will also be squeezed out through the gall bladder,
4:21
and then down through the cystic duct. Now the cystic duct, and the common hepatic duct
4:26
will unite, and form the bile duct. I now wanna focus on the gall bladder
Gall Bladder
4:31
a little bit before we continue, because it has some important anatomical structures.
4:35
The Gallbladder is directed forward under the Liver. And it forms a fossa called the fossa
4:40
for the Gallbladder. Now let’s isolate the gall bladder with the bile pathway.
4:45
Here again you see the Left Hepatic Duct and the Right hepatic duct. They go together and form the
4:50
common hepatic duct. Then the gall bladder has the cystic duct, which unites with the common hepatic
4:56
duct to form the bile duct. Now the Gallbladder is
5:00
divided into three distinct parts. We have the rounded anterior part call the Fundus.
5:05
And then there’s a body of the Gallbladder and then there’ the neck of the Gallbladder,
5:09
which continues into the duct I mentioned earlier, the cystic duct or the ductus cysticus.
5:16
Let’s now go ahead and open up the gall bladder to look at the Layers of the gall bladder wall.
5:21
So let’s go ahead and take one small part of the gall bladder, and look at it histologically.
5:26
Now the walls of the bile ducts and the gall bladder are formed by three layers.
5:31
We have the inner one, the Tunica mucosa highlighted in blue. It has a Tunica Muscularis,
5:37
then a Tunica Serosa which you see here, or a tunica adventitia. Notice, though,
5:43
that usually there’s always a tela submucosa underneath the Tunica mucosa, but the Gallbladder
5:49
and the bile ducts doesn’t have that, they don’t have a tela submucosa under the tunica
5:52
mucosa. They only contain three layers. So keep that in mind. Now let’s do the mucosa first.
6:01
The Tunica mucosa has these folds on it called the Mucosal Folds of the Gallbladder.
6:06
That is those folds here you see histologically, which you can also see on this on the gall bladder
6:10
grossly. They’re mostly present when the gall bladder is empty, and you’ll find them on all
6:15
three parts of the Gallbladder. Another structure you’ll find on the tunica mucosa, in the region
6:21
of Neck of the Gallbladder and Cystic duct as you see here, are these extra folds called the
6:26
Spiral Folds. They kind of surround the walls of the Neck of Gallbladder and the cystic duct.
6:32
Beneath the epithelial layer, you’ll find numerous glands, called mucosal glands that lubricates the
6:38
lumen of the gall bladder and the bile ducts. So that is the Tunica Mucosa. Next, we have the
6:45
muscular layers—the Tunica muscularis. And what’s interesting here is that usually, the Tunica
6:50
muscularis has two different muscle layers, but on the gall bladder and the bile pathway, there’s
6:56
only has one layer of muscle. One layer called the Circular Muscle fibers, or stratum circulare. Keep
7:02
that in mind that this goes for the rest of the bile ducts aswell, and not only the Gallbladder.
7:07
All right, and then the outer layer, we call this one Tunica Serosa, or Tunia Adventitia.
7:13
And so if you remember the differences between the Tunica serosa at Tunica adventitia.
7:18
Tunica adventitia is only a connective tissue covering, while the Tunica serosa is going to
7:24
be a slippery surface of the serous membrane formed by the peritoneum.
7:29
So if look at the the bile pathway anteriorly. This is how the coverings are distributed.
7:34
the only part covered by the Tunica adventitia, is in orange here, which lies in the fossa for
7:41
the Gallbladder. But the rest of the Gallbladder is covered by the peritoneum and therefore has the
7:46
name Tunica serosa. And the same goes for the Common Hepatic Duct, The cystic Duct and the
7:50
Bile duct, they’re all covered by the peritoneum. And that is through the Hepatoduodenal Ligament.
7:56
They lie within the hepatoduodenal ligament, which is a part of the peritoneum. Forming this slippery
8:01
surface called the Tunica Serosa. So that was the walls of the gall bladder and the bile ducts.
Bile Pathway
8:07
So if you go back to this picture again, we know that the common hepatic duct
8:12
and the cystic duct unites and form the bile duct or the ductus choledoctus. So
8:18
now I wanna to focus on this a little bit. So the bile duct is Here it goes behind the
8:23
Superior part of the duodenum and the pancreas. Let’s remove a part of the pancreas so we can
8:28
see it better. So The bile duct is about 7 centimeters long, and if you look down here,
8:34
we can see that the bile duct joins with the pancreatic duct, to form the Hepatopancreatic
8:40
Ampulla. Let’s change the angle, and do that again. Here we see the Bile Duct.
8:45
It Joins with the Pancreatic Duct, which secretes pancreatic enzymes with the Bile,
8:50
aiding the digestion. These two join and form the Hepatopancreatic Ampulla. They then open up
8:56
into the duodenum’s descending part forming the Major Duodenal Papilla in the duodenum.
9:02
Here, logical enough, you need something that makes sure the food you eat
9:06
doesn’t go into the bile duct as it secretes the Bile. And it does that through this sphincter here
9:12
formed by the Tunica muscularis. This sphincter it forms is called this Hepatopancreatic Sphincter,
9:18
or the Sphincter of Oddi. Alright, so now we’ve gone through
9:22
the anatomy of the Liver, the Gallbladder, and the bile pathway. Let’s now look at the anatomy
Pancreas
9:27
of the pancreas a little bit. The pancreas looks like this,
9:30
and it measures about 14-18cm long, about 2-3 cm wide and it weights around 60-100 grams,
9:39
so it’s a tiny organ, but it’s a very important organ. The pancreas has an exocrine function,
9:48
Meaning it produces its pancreatic juice, containing digestive enzymes which helps
9:52
with the breakdown of food, and bicarbonate which neutralizes the hydrocholic acid from the stomach.
9:58
But it also ahs an endocrine function, where it releases important hormones into the bloodstream
10:03
from the cells of Langerhans. Insulin and Glucagon are examples of important hormones released here,
10:09
regulating the blood sugar. So the pancreas really does
10:12
have an essential function in the body. Now the pancreas has three parts. It has a
10:16
Pancreatic Head, it has a body, and it has a tail. The lowest point, which is the pancreatic head,
10:22
lies in front of L2 vertebra, and the highest point is until L1. And at the end of the tail,
10:31
you’ll find the spleen, resting right next to it. Now topographically, here I’ve faded away
10:36
all other structures so that we can see the pancreas. the pancreas lies in the epigastric
10:40
region and the left hypochondriac region. So the head and body is in the epigastric and the
10:47
tail is in the left hypochondriac region. All right, if we go back to this picture again.
10:52
This is the posterior view of the pancreas after removing some parts of it. Remember the bile duct,
10:58
will join the pancreatic duct, and form the hepatopancreatic Ampulla, The pancreatic duct
11:04
you see here is the main pancreatic duct, but if you look a little superior to it, you’ll see the
11:09
accessory pancreastic duct, which secrets the same juice as the pancreatic duct containing digestive
11:15
enzymes and bicarbonate for neutralizing the content that comes from the stomach.
11:20
And if we flip this image, you’ll see that the pancreatic duct
11:24
opens as the major duodenal papilla, while the accessory pancreatic duct, opens as the minor
11:30
duodenal ampulla, located a little superiorly. So that was everything I had for the Bile pathway,
11:36
Gallbladder, and the pancreas. If you found this video helpful;
11:39
Please put a like, share, comment. Whatever you find convenient to you. See you next time