Digestive System (The Small Intestine and its functions: (Circular Folds:…
The Small Intestine and its functions:
: They slow down the chyme in the small intestine.
They look like fingers, they increase surface area.
: Mechanical digestion: Segmentation
Chemical digestion: Lots of enzymes are added here. Lots of absorption.
Microvilli / Brush border
: These structures are on each of the villi, and they further increase surface area.
These glands secrete alkaline mucus to neutralize acid from the stomach. It provides the small intestine with protection against its own powerful chemicals.
Peyer Patches (Lymphatic nodules)
Collections of lymphocytes are what make up the lymphatic nodules.
These glands secrete watery intestinal juices to keep things in a constant liquid state.
The function of the
is that It keeps the contents in the large intestine there; and not moving backward to the small intestine.
The Stomach and its functions:
The Gastric Glands continue from the Gastric Pits that are in the General Layer (Mucosa) of the stomach. Gastric glands make up the cardiac sphincter and the pyloric sphincter, as well as located in the body and the fundus of the stomach. Depending on their location, they are made up of different types of cells. The Mucous neck cells are located in the neck of the gastric glands.
(Oxyntic): (middle region of the gastric glands) Produces hydrochloric acid (HCl) and intrinsic factor. Intrinsic factor is needed for the absorption of vitamin B12. Vitamin B12 is needed for erythrocytes production.
-Food Storage -Mechanical digestion and churning. This turns food into chyme -Chemical digestion
Chief cells/Chief glands
: (mainly in the basal part of the gastric glands) Makes and secretes pepsinogen. Pepsinogen + acid = pepsin. Pepsin is an enzyme that breaks down proteins/fats. (gastric lipase).
prevents the reflux of acid into the esophagus. It is weaker than the pyloric sphincter. (heartburn is the acid in the esophagus that leaked through a weak cardiac sphincter).
regulates the amount of chyme moving on to the small intestine. It moves on to the small intestine slowly (the stomach is a holding place for food until it’s ready to be moved to the small intestine).
in the stomach increases the storage capacity.
Compare and contrast the locations of the mesenteries:
(mesentery proper, mesocolon, lesser omentum and greater omentum)
: This is connected to the transverse colon and the sigmoid colon on the posterior side.
This starts at the lesser curvature of the stomach and it goes to the liver.
is located within the jejunum and the ileum of the Small Intestine.
This can migrate. (Example: if the appendix is infected, the greater omentum can migrate to that area, through natural movements from the body.) The Greater Omentum can cover the infected organ, thereby protecting all of the surrounding tissue. The greater omentum is also used for fat storage.
Large Intestines, Rectum and Anal Canal
: Absorption of water and electrolytes (ions)
Storage place. There are well developed muscles to expel feces.
: Last inch or so of the large intestine.
There are mucus glands located here for lubrication. Internal (Smooth Muscles/Involuntary) Sphincters
and External (Skeletal Muscles/Voluntary) Sphincters.
Three longitudinal strips of muscle. They contract and pull the large intestine into pouches / sacks.
: These are the pouches / sacks.
: Little pieces of fat on our large intestine
Mesentery and its function:
2.) Stores Fat
3.) Provides a place for blood vessels and nerves to go
1.) It holds organs in place
This is a double layer of peritoneum from the body wall to digestive organs.
Function of the Liver, Gallbladder and Pancreatic Acini
:The gallbladder stores bile (made by the liver)
The Pancreatic acini are cells that make up the bulk of the pancreas. They are exocrine glands that produce and secrete 22+ enzymes that enter the duodenum.
-The Lives makes bile (which is stored in the gallbladder).
The bile emulsifies fat (breaking it into smaller pieces)
-Filters toxins out of the blood
-Stores glucose (sugar) as glycogen
-Stores some vitamins
-Processes fats and amino acids
-Makes blood proteins
Gastrointestinal (GI) Tract / Alimentary canal and the accessory digestive organs:
The GI is the tube. It starts at the mouth and ends at the anus. Again, the GI Tract is simply a tube. The organs of the GI Tract include: The mouth, Pharynx, Esophagus, Stomach, Small Intestine, Large Intestine, and anus.
The accessory digestive organs are organs we find along the tube. These include: The teeth, tongue, gallbladder, salivary glands, liver and pancreas. The Accessory organs secrete saliva, bile and enzymes to aid in breaking down the foodstuff.
Intraperitoneal and Retroperitoneal Organs:
are those within the peritoneal. The digestive system organs that are located here include: Liver, Stomach, Transverse Colon, Jejunum, Ileum and the Sigmoid Colon.
are those outside the peritoneal. The digestive system organs that are located outside the peritoneal include the: Duodenum, Pancreas, Ascending Colon, Descending Colon and Rectum.
Mechanical Digestion and Chemical Digestion
Mechanical Digestion is cutting up food to make it into smaller pieces.
The teeth start the mechanical process, Stomach, Small Intestine (A movement in the small intestine, called segmentation occurs). This is all part of MECHANICAL DIGESTION.
Chemical Digestion is when chemicals (Specifically enzymes) are added.
It starts in the mouth with saliva (Chemicals from the Pancreas), Stomach (More chemical added), Small intestine.
Major functions of the digestive system:
Break down food into small enough pieces to be absorbed (To eventually go into the circulatory system – blood)
Eliminate what we can’t break down.
Pathway that food travels as it enters the oral cavity and leaves the anus:
Oral Cavity :check: Pharynx :check: Esophagus :check: Stomach :check: Small Intestine (Has three parts) :check: Large Intestine :check: Rectus :check: Anus
is a movement of continual contraction, and than a period of rest in the musculature of the organ wall. Its next effect is to squeeze food from one organ to the next. It’s the esophagus through the large intestine.
Heart 2. Arteries (Digestive System) 3. Capillaries 4. Veins (Hepatic Portal Vein) 5. Capillaries (of the liver) 6. Veins (Hepatic Portal Vein and Inferior Vena Cava) 6. Back to the heart