Digestive system

• The digestive system is made up of the mouth, oesophagus, stomach, small intestine (duodenum, jejunum, ileum), large intestine (caecum, colon, rectum) and anus.
• Mechanical (physical)

  Chew

  Tear

  Grind

  Mash

  Mix
• Chemical

  Enzymatic reactions to improve digestion of

  Carbohydrates

  Proteins

  Lipids
• Digestion phases include

  Ingestion

  Absorption

  Assimilation

  Elimination
• Tongue mixes food with saliva
•  Tongue mixes

  food with saliva (contains

  amylase, which helps

  break down starch).
• Teeth mechanically break

  down food into small

  pieces
• ESOPHAGUS Approximately 20 cm long.
• Esophagus - Secrete mucus
• Moves food from the throat to

  the stomach using muscle

  movement called peristalsis
• If acid from the stomach gets in here, That’s heartburn
• Esophagus - Approximately 20 cm long.

  Functions include:

  Secrete mucus

  Moves food from the throat to

  the stomach using muscle

  movement called peristalsis
• Stomach - J-shaped muscular bag that stores the food you

  eat, breaks it down into tiny pieces.
• Stomach - Mixes food with Digestive Juices that contain

  enzymes to break down Proteins and Lipids.

  Acid (HCI) in the stomach Kills Bacteria.
• Food found in the stomach is called Chyme.
• Small intestines are roughly 7 meters long
• Lining of intestine walls has finger-like

  projections called villi, to increase surface

  area.
• . Nutrients from the food pass into

  the bloodstream through the small

  intestine walls.

  · Absorbs:

  80% ingested water

  Vitamins

  Minerals

  Carbohydrates

  Proteins

  Lipids
• Small intestines - Secretes digestive enzymes
• Duodenum: The first and shortest section, which is

  roughly shaped like a "C." Food passes from the

  stomach to duodenum through a muscle called the

  pyloric sphincter.
•  Food passes from the

  stomach to duodenum through a muscle called the

  pyloric sphincter.
• Iron is absorbed in the duodenum.
•  Jejunum: Sugars, amino acids, and fatty acids are

  absorbed in this part of the small intestine.
• . Ileum: This last part of the small intestine is where

  vitamin B12, bile acids, and other nutrients are

  absorbed.
• LARGE INTESTINE

  About 1.5 meters long

  Accepts what small intestines don't

  absorb
• Rectum - short term storage which

  holds feces before it is expelled
• Cecum

  This pouch-like section at the beginning of

  the large intestine is around two inches

  long. It absorbs digestive fluids passing

  out the ileum of the small intestine, and

  passes the waste material on to the colon.
• Appendix

  At the bottom of the cecum, there is a closed

  tube called the appendix or vermiform

  appendix.
• The appendix is a vestigial

  organ that has lost all or at least most of its

  original functions in humans through

  evolutionary processes.
• Colon

  As one of the parts of the large intestine, the colon can be the main section of

  the large intestine. Sometimes, people use the word colon to refer to the

  whole large intestine. The majority of water absorption takes place here
• The ascending colon uses muscle contractions to push up

  any undigested food products from the cecum to the top of the abdominal'

  cavity, just below the right bottom edge of the liver.
• Transverse colon; This second section of the colon transverses the anterior

  abdominal wall from the right to the left-hand side of the abdomen,

  immediately under the stomach.
• Descending colon: The food particles travel down the descending colon on

  the right-hand side of the abdomen, close to the spleen.
• Sigmoid colon: This is an S-shaped section at the end of the colon. It bends

  inwards towards the small intestine, before terminating in the rectum.
•  Rectum

  Around the end of the large intestine, the

  rectum is around 1-1.6 inches (2.5-4 cm)

  long.
• The rectum opens to the outside through

  the anus. Feces exit the anus through the

  contraction of sphincter muscles, in a

  process termed defecation.
• The large intestine

  Absorbs more water

  Concentrate wastes
• ASSIMILATION

  . The process of transport and use the absorbed nutrient in the body.
• Glucose is used by all the cells for energy production.
•  Excess glucose is stored in the liver as glycogen.