Transcript Period 4 Digestion Lecture

Digestive System
Andrew Perez, Andres Sanchez, Valerie Rolon
Alimentary Canal
Extends from mouth to anus, includes accessory organs.
-Mouth, pharynx,
esophagus, stomach, small intestine, large intestine, anal canal.
Accessory organs - salivary glands, liver, gallblader, pancreas
8 meters long
4 layers
Mucosa
Submucosa
- Muscular layer
Mouth
First organ of Alimentary Canal
Receives food
Mastication
Tongue helps push food for swallowing
Teeth (Dentes)
Cut, tear, grind
Found in buccal (oral) cavity
Breaks food down
Enable food to be mixed w/ saliva
Salivary Glands
❖ Saliva
➢ begins chemical digestion of carbohydrates
➢ Cleans teeth & mouth
➢ Binds broken down food
❖ 2 Types of secretory cells
➢ Serous Cells
■
Secrete salivary amylase
Salivary Glands (Cont.)
Three Major Glands
Parotid
○ Largest
○ secrete salivary amylase rich liquid
Submandibular
○ Secretes equally serous liquid
○ Mucus
Sublingual
Salivary Glands (Cont.)
2 Types of secretion stimuli
Sympathetic - Impulses that secrete viscous saliva
Parasympathetic - secrete saliva, activates by senses
Esophagus
Located in your throat near the trachea. Food is
swallowed and then received in esophagus.
The food undergoes a process of muscle contractions
called Peristalsis and is then moved to the
stomach.
Pharynx - connects nasal and oral cavities w/ larynx &
esophagus
Stomach
Located between esophagus and duodenum.
7 structures: Cardia, cardial notch, fundus,
body, pyloric antrum, pyloric canal, and
pylorus. involved in second part of
digestion following mastication (chewing).
Stomach (Cont.)
4 Regions
Cardiac region - small area near esophageal
opening
Fundus Region - Storage area
Pyloric region - narrows and becomes pyloric
canal
Body region - largest, central region
Small Intestine
3 segments:
1. Duodenum: the first part of the small
intestine immediately beyond the stomach,
most chemical digestion happens here.
2. jejunum: specialized for the absorption, by
enterocytes, of small nutrient particles
which have been previously digested by
enzymes in the duodenum.
3. ileum: absorbs vitamin B12 and bile salts
and whatever products of digestion were
not absorbed by the jejunum.
Large Intestine
Water absorbed here and remaining
waste material is stored as feces.
Located on the bottom left hand side of
the abdomen, S shaped connection
between descending colon and
rectum.
Pancreas (Accessory)
Location is across the back of abdomen
behind the stomach
The head of the pancreas is on the right
side of the abdomen and is connected
to the duodenum.
Function is to further break down food
after stomach, the gland also produces
the hormone insulin and secretes it into
the bloodstream in order to regulate
the body's glucose or sugar level.
Liver
Filters and processes blood as it
circulates through the body.
It metabolizes nutrients, detoxifies
harmful substances, makes blood
clotting proteins, and performs
many other vital functions.
Located in upper right portion of the
abdomen above the stomach and
below the diaphragm.
Gallbladder
releases bile, via the cystic duct, into
the small intestine to help break
down the foods you eat —
particularly fatty foods. Located
just beneath the liver.
Rectus
receive stool from the colon, to let
the person know that there is stool
to be evacuated, and to hold the
stool until evacuation happens.
Located at end of Large intestine.
Hormones
Chemical messengers secreted in bloodstream and stimulate distant parts of the
digestive tract.
1. Gastrin - stimulates the secretion of gastric acid by the parietal cells
2. Secretin - Stimulates the pancreas to secrete digestive fluids rich in bicarbonate
3. Cholecystokinin (CCK) - Peptide hormone responsible for stimulating the
digestion of fat and protein.
4. Glucose insulinotropic peptide (GIP) - Induces insulin secretion
5. Motilin - stimulates the production of pepsin
Anus
last part of the digestive tract. It is a
2-inch long canal consisting of the
pelvic floor muscles and the two
anal sphincters (internal and
external).
Located at end of Large intestine
below the rectum.
Digestion
A. Mechanical- Physically breaking down food for digestion(
chewing)
B. Chemical- Begins in mouth when food mixes with saliva
Next in the stomach and intestines with the use of acid and
enzymes
How do macromolecules move through the digestive
tract?
Starches & Sugars- made up of small building blocks called monosaccharides & are
broken down by amylase enzymes and absorbed in the blood stream
Proteins- made up of amino acids, broken down by protease enzymes. Starts after
the digestion of starches and takes longer to digest.
Fats- made up of fatty acids and glycerol. Fatty acids are broken off and absorbed.
Enzymes & Hormones
hormones affect the behavior of the cells throughout the body. Example: Glucagon breaks down the
macromolecule glycogen into many glucose molecules that are then released into the bloodstream.
enzymes break down break down foods into smaller molecules so that the body and absorb it easier.
Bibliography
http://www.ivyroses.com/HumanBody/Teeth/
http://www.innerbody.com/image/digeov.html
http://www.livestrong.com/article/465047-macromolecules-in-the-human-digestive-system/
https://en.wikipedia.org/wiki/Stomach
www.henryspink.org/secretin.htm
http://www.innerbody.com/image/dige02.html
http://www.scienceclarified.com/Di-El/Digestive-System.html