Download You will be able to identify the structures of the digestive system.

Objective: You will be able to identify
the structures of the digestive system.
Do Now:
• Read page 978
• List the accessory organs
Figure 41.12 The four stages of
food processing
Small
molecules
Pieces
of food
Mechanical
digestion
Chemical digestion
(enzymatic hydrolysis)
Nutrient
molecules
enter body
cells
Undigested
material
Food
1 INGESTION
2 DIGESTION
3 ABSORPTION
4 ELIMINATION
Figure 41.13 The human digestive system
Activity
• For each digestive organ you need to:
– Locate in pig and cut out if possible
– Draw organ and outline its digestive
functions FULLY
– Write down any disorders that you can
think of that would be associated with each
organ.
• Use laptop to find and describe a
disorder for that organ. Be sure to
include how the disorder is related to its
function.
Oral Cavity
• Mechanical digestion breaks food into
smaller pieces
– Increases surface area for chemical digestion
• Chemical digestion of starch occurs here
– Done by salivary amylase
Esophagus
• No digestion occurs here
• It moves food from oral cavity to stomach
by using muscles
– Called peristalsis
Figure 41.16 From mouth to stomach: the swallowing reflex
and esophageal peristalsis (layer 1)
Bolus of food
Tongue
Epiglottis
up
Pharynx
Glottis
Larynx
Trachea
To lungs
Esophageal
sphincter
contracted
Esophagus
To stomach
Figure 41.16 From mouth to stomach: the swallowing reflex
and esophageal peristalsis (layer 2)
Bolus of food
Tongue
Epiglottis
up
Pharynx
Glottis
Larynx
Trachea
To lungs
Esophageal
Epiglottis
sphincter
down
contracted
Esophagus
To stomach
Glottis up
and closed
Esophageal
sphincter
relaxed
Figure 41.16 From mouth to stomach: the swallowing reflex
and esophageal peristalsis (layer 3)
Epiglottis
up
Bolus of food
Tongue
Glottis
down
and open
Epiglottis
up
Pharynx
Glottis
Larynx
Trachea
To lungs
Esophageal
Epiglottis
sphincter
down
contracted
Esophageal
sphincter
relaxed
Esophageal
sphincter
contracted
Esophagus
To stomach
Glottis up
and closed
Relaxed
muscles
Contracted
muscles
Relaxed
muscles
Esophagus
Cardiac orifice
Stomach
5 µm
Pyloric
sphincter
Interior surface of stomach.
The interior surface of the
stomach wall is highly folded
and dotted with pit leading
into tubular gastric glands.
Small
intestine
Folds of
epithelial
tissue
Epithelium
3
Pepsinogen
Pepsin (active enzyme)
2
HCl
Gastric gland. The gastric
glands have three types of cells
that secrete different components
of the gastric juice: mucus cells,
chief cells, and parietal cells.
1
2 HCl converts
pepsinogen to pepsin.
Mucus cells secrete mucus,
which lubricates and protects
the cells lining the stomach.
3 Pepsin then activates
more pepsinogen,
starting a chain
reaction. Pepsin
begins the chemical
digestion of proteins.
Chief cells secrete pepsinogen, an inactive form of the
digestive enzyme pepsin.
Parietal cell
Parietal cells secrete
hydrochloric acid (HCl).
1 Pepsinogen and HCI
are secreted into the
lumen of the stomach.
Chief cell
Stomach
• Mechanical digestion occurs by the
grinding of the stomach’s muscles
• Chemical digestion of proteins begins here
– Gastric glands in stomach release a HCl and
protease
– The HCl provides a highly acidic environment
– The protease actually breaks down the
protein
Figure 41.19 The duodenum
Liver
Bile
Gallbladder
Stomach
Acid chyme
Intestinal
juice
Pancreatic juice
Pancreas
Duodenum of
small intestine
Small Intestine
• Lipid digestion starts here
• Most of the chemical digestion occurs here
– Intestinal glands and the accessory organs
help to digest food
• Liver, gall bladder and pancreas
• All of the absorption of food into the body
occurs here
• No food is digested AFTER it leaves the
small intestine
Figure 41.19 The duodenum
Liver
Bile
Gallbladder
Stomach
Acid chyme
Intestinal
juice
Pancreatic juice
Pancreas
Duodenum of
small intestine
Accessory organs
• The liver makes the bile but it stores it in
the gall bladder
• It’s the gall bladder that actually secretes
bile into the small intestine
– Bile emulsifies fats (breaks them down)
• The pancreas secretes amylase, protease
and lipase
Figure 41.19 The duodenum
Liver
Bile
Gallbladder
Stomach
Acid chyme
Intestinal
juice
Pancreatic juice
Pancreas
Duodenum of
small intestine
Large Intestine
• This organs main function is to absorb
water
• It does NOT absorb food nor does it digest
food!!!!
End of the line
• Strong peristaltic action from the rectum
pushes waste out of the anus
Activity
• Create story about the digestive canal of
horrors where a group of teenage worm
friends enter ride but are digested by
enzymes
• Remember that only some of carbohydrate
and protein digestion happens outside
intestines
• Be sure to include each structure and
describe in full detail what they do.
Figure 41.18 Ulcer-causing
bacteria
Bacteria
1 µm
Mucus
layer of
stomach
Disorders of the Digestive
System
• Ulcers are erosions of the digestive tract
• Appendicitis is the infection and
inflammation of the appendix
• Gallstones is the accumulation of
hardened cholesterol deposits on the gall
bladder
Disorders continued
• Constipation occurs when the large
intestine absorbs too much water
• Diarrhea occurs when the large intestine
does NOT absorb enough water