Download lab 7 digestive system 1 - Dr. Justo Lopez Website

Lab # 6
Digestive System-1
Digestive
tract
- Oral cavity
- Pharynx
- Esophagus
- Stomach
- Small intestine
- Large intestine
Accessory
organs
- Teeth
- Tongue
- Salivary glands
- Liver
- Gallbladder
- Pancreas
Digestive
System
Pharynx
Tongue
and teeth
Salivary glands
Oral cavity
Esophagus
Liver
Gallbladder
Stomach
Pancreas
Large intestine
Small intestine
Most of the digestive tract follows the basis structural plan with digestive
tract wall consisting of the following tissue layers, in order from the inner to
the outer surface:
Cross
section of the
esophagus
1- Mucosa:
Stratified squamous
epithelium
Lamina propria
Muscularis mucosae
Stratified squamous
epithelium
2- Submucosa
3- Muscularis externa:
Inner circular layer
Outer longitudinal layer
Simple columnar
epithelium
4- Serosa
Stratified squamous
epithelium
Diaphragm
Stomach
Esophagus
Simple columnar epithelium (it
contains gastric pits and gastric
glands)
Stratified squamous
epithelium
(also in oral cavity,
pharynx and esophagus).
Three layers of smooth
muscle in the muscularis
externa: outer longitudinal,
middle circular, and inner
oblique.
Two layers of smooth
muscle in the muscularis
externa: outer
longitudinal and inner
circular.
Folds of the mucosa
called rugae.
Longitudinal folds of the
mucosa that allow for
expansion
Taeniae coli
Small Intestine
Simple columnar epithelium
with microvilli (it contains crypts
of Lieberkuhn and intestinal
glands)
Two layers of smooth muscle in
the muscularis externa: outer
longitudinal and inner circular.
Transverse folds of the mucosa
called plicae circulares, and
fingerlike projections called villi.
Large Intestine
Transverse folds
of the wall called
haustra.
Simple columnar
epithelium without villi
(it is dominated by
mucous cells)
Two layers of smooth
muscle in the muscularis
externa: outer
longitudinal reduced to
the taeniae coli, and
inner circular.
The Oral Cavity
1- The Lips and the Cheeks, 2- The Palate
Functions: 1- Ingestion takes place, 2- Mechanical and chemical digestion
start
Soft palate
Hard palate
Uvula
Upper lip
Cheek
Vestibule
Lingual
frenulum
Lower lip
Tongue
Functions:
The Tongue
1- Mechanical digestion, 2- Keeping the food against the teeth during
chewing and swallowing, 3- Analysis of food (touch, temperature,
and taste receptors), 4- Secretion of mucus and lingual lipase, 5Helping in speech
(taste
buds)
(friction)
(taste
buds)
The Salivary Glands
Functions: They secret saliva which 1- Cleanses the mouth, 2- Dissolves
and moistens food, and 3- Contains enzymes that starts the break down
of the carbohydrates
Parotid ducts
Parotid glands
Sublingual glands
Submandibular
glands
Mucous cells
(Mucins)
Serous cells
(Enzymes)
Duct
The Teeth
Functions: Mechanical break down of food (chewing or mastication)
Enamel
Dentin
Crown
Neck
Pulp
cavity
Gingiva or
gum
Periodontal
ligament
Root
Cementum
Root canal
Blood vessels
and nerve
The Teeth
Central incisor
Lateral incisor
Cuspid or
canine
(Blade-shape teeth: Clipping and
cutting)
(Conical with a sharp
ridgeline and a pointed
tip: Tearing or slashing)
Upper
dental
arch
Molars
Bicuspids or
premolars
(Flattened crown with
prominent ridges: Crushing,
smashing and grinding)
(Very large flattened
crowns with prominent
ridges: Crushing and
grinding)
Total: 32 permanent
or secondary teeth
Lower
dental
arch
Total: 20 primary,
temporary or
deciduous teeth
The Pharynx
Function: It propels the food to the esophagus.
Nasopharynx
Pharyngeal
tonsil
(air passageway)
Eustachian or
auditory tube
Oropharynx
(food and air passageway)
Laryngopharynx
(food and air passageway)
Soft palate
Palatine tonsil
Lingual tonsil
Epiglottis
Glottis
The Esophagus
Function: It carries food and liquids to the stomach
Mucosa
The Stomach
Fundus
Cardia
Serose
Muscularis
Externa:
Pyloric region:
Longitudinal
layer
Lesser
curvature
Pyloric Antrum
Circular
layer
Pyloric canal
Pyloric sphincter
Oblique
layer
Mucosa
Greater
curvature
Duodenum
Rugae
Simple
columnar
epithelium
Histology of the Stomach
It secrets alkaline
protective mucus
Mucosa
Gastric pit
Lamina
propria
Muscularis mucosae
Submucosa
Oblique muscle
Circular muscle
Longitudinal
muscle
Serosa (visceral
peritoneum)
Mucous cells
They produce alkaline
protective mucus
Gastric
pit
Parietal cells
They produce HCl and
Intrinsic Factor
Chief cells
They produce Pepsinogen
Gastric
gland
(In new born and infants
produce rennin and gastric
lipase)
G cells
They are enteroendocrine
cells that produce Gastrin,
Somatostatin, Histamine
and Serotonin
The Small Intestine
Macroscopic anatomy
It is the major digestive and absorptive organ of the body. It extends from the
pyloric sphincter to the ileocecal valve (19.7 ft )
Functions:
1- To complete digestion
2- To absorb 99% of the digested nutrients
Duodenum (10 inches)
It receives the pancreas and liver secretions
that mix with the chyme
Jejunum (8.2 ft )
It is where most chemical digestion
and absorption take place
Ileum (11.48 ft )
It is where digestion is completed. It
ends at the ileocecal valve, which
control the passage of undigestive
materials to the large intestine
Microscopic anatomy
Plicae Circularis
They increase the surface area for absorption
They make chyme spiral through the lumen to mix with intestinal juice
They slow movement to allow time for absorption
Microscopic anatomy
Mucosa
General Structure of
the Small Intestine
Highly folded
lining where
absorption
occurs
Submucosa
Connective
tissue
containing
blood vessels
and nerves
Plicae
Muscularis
externa
Peristalsis: The contraction of the
smooth muscle that produces waves,
which push materials along the length
of the digestive tract
Serosa
Connective tissue
Circular and
longitudinal muscle
layers used for
peristalsis
Absorption of
nutrients
Microvilli
Epithelium
(Simple columnar)
Lacteal
Villus
Plica
Capillary
network
Nerve
Arteriole
Lymphatic vessel
Venule
F- The Large Intestine
Functions
Large colon
1- Reabsorb water
2- Compact undigested food stuff into
feces
3- Eliminate faces
4- Absorb bacterial vitamins
5- Store fecal matter until defecation
Cecum
Ileocecal
valve
Rectum
Anus