DIGESTIVE SYSTEM. FUNCTIONS 1. Ingestion. 2. Digestion. 3. Absorption. 4. Defecation.
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Transcript of DIGESTIVE SYSTEM. FUNCTIONS 1. Ingestion. 2. Digestion. 3. Absorption. 4. Defecation.
DIGESTIVE SYSTEM
FUNCTIONS1. Ingestion.2. Digestion.3. Absorption.4. Defecation.
COMPONENTS(1) Alimentary
(Gastrointestinal) tract which performs the whole digestive functions.
(2) Accessory organs: assist the process of digestive break down.
ALIMENTARY CANAL (GIT)Muscular tube. Length: In the cadaver 9
m.In the living person , is
shorter because of the muscle tone.
Continuous, Coiled & Hollow.
Winds around the ventral body cavity.
Opens at both ends.
COMPONENTS OF GITMouth.Pharynx.Esophagus.Stomach.Small intestine.
Large intestine.
ACESSORY DIGESTIVE ORGANSSalivary glands.
Teeth.Liver & Gall bladder.
Pancreas.
MOUTH (oral cavity)A mucous membrane
lined cavity.It is the site of food
entry.Boundaries :Anterior : lips (labia). Lateral : cheeks.Roof : hard and soft
palates.Floor : tongue.
ORAL CAVITYDivided into :Vestibule :A space between the
lips and cheeks externally and the teeth and gums internally.
Oral cavity proper: :The area contained
by the teeth.It contains
Lymphoid tissue :Palatine tonsil and
lingual tonsil.
PHARYNXOropharynx and
Laryngopharynx are parts of the alimentary tract.
Food is propelled through the pharynx into the esophagus by peristalsis.
ESOPHAGUSA muscular tube
25 cm (10) inches long.
Begins as a continuation of the pharynx.
Terminates in the stomach.
It conducts food to the stomach.
STOMACH Position : On the left side
of the abdominal cavity under the liver and diaphragm.
Shape : C – shaped.
Length : 25 cm
PARTS1. Cardiac region : near
the heart.2. Fundus : the
expanded part lateral to the cardiac region.
3. Body : mid portion. 4. Pylorus: the
terminal part of the stomach. divided into :
Antrum.Pyloric canal : cavity
of pylorus.
CURVATURESGreater : convex
lateral surface of the stomach.
Lesser : concave medial surface.
SPHINCTERSPhysiological:Cardioesophageal:Where the
esophagus opens into the stomach.
Anatomical:Pyloric :where the stomach
is continuous with the small intestine.
PERITONEUMLesser omentum :It extends between
the liver and the lesser curvature.
Greater omentum :It extends between
the greater curvature and the transverse colon .
SMALL INTESTINEIt is the major
digestive organ (2.5 -7) m in the living person.
Extends: from the Pyloric
sphincter to the Ileocecal valve.
Divided into:Duodenum,
Jujenum & Ileum.
DUODENUMThe shortest part of
the small intestine (nearly 5%).
C-shaped.Receives the
openings of the pancreatic and bile ducts.
JUJENUM & ILEUM2. JUJENUM :Contributes nearly
40% of the small intestine.
3. ILEUM :Contributes nearly
60% of the small intestine.
It joins the large intestine at the ileocecal valve.
LARGE INTESTINELarger in diameter and
Shorter in length (1.5) m than the small intestine.
It frames the small intestine on three sides.
It extends from the Ileocecal valve to the Anus.
It dries the indigestible food residue and eliminates it out as feces.
CRITERIA(1) Teniae Coli : three
bands of muscle that can be seen externally. It is formed from the longitudinal muscle layer.
(2) Haustra : small pocket like sacs in the wall due to the muscle tone.
(3) Appendices epiploicae:
peritoneal folds full of with fat.
PARTS(a) Cecum : first part of the
large intestine.(b) Appendix : A wormlike, It hangs
from the cecum. It is an ideal site for
bacteria to multiply and accumulate .
COLON1. Ascending: It travels up the right
side of the abdominal cavity.
It makes a turn, the right colic (hepatic) flexure.
2.TransverseIt travels across the
abdominal cavity.It makes the left colic
(splenic ) flexure.
COLONDescendingIt travels down the left
side of the abdominal cavity and enters the pelvis.
Sigmoid (pelvic) It is S- shaped and lies
in the pelvis. Rectum.
Anal Canal and Anus.
ANAL SPHINCTERSThe anal canal has
two sphincters :1. External
(voluntary) formed of skeletal muscle.
2. Internal (involuntary) formed of smooth muscle.
TEETHDeciduous (milk) teeth :They begin to appear
about (6) months.The first teeth to erupt are
the lower central incisors.At the age of two years
they are (20) in number.The milky teeth fall out
between ages (6-12) years.Permanent teeth :Fully erupted at the end of
adolescence. They are 32 in number.
Third molars (wisdom) Erupt later at ages (17 –25) years.
SALIVARY GLANDSThree pairs of salivary
glands(1) Parotid glands They are the largest.They lie anterior to the
ear.They empty their secretion
into the vestibule.(2) Submandibular glands.(3) Sublingual glands.They empty their
secretions into the floor of the mouth cavity proper.
LIVERThe largest gland
in the body (exocrine & endocrine).
It lies in the right side of the body under cover of the diaphragm.
It is formed of (4) lobes.
LIVERIt is suspended
to the diaphragm and anterior abdominal wall by the peritoneal fold (Falciform Ligament).
FUNCTIONSExocrine gland: It produces bile.Bile leaves the liver
through the common hepatic duct.
Enters the duodenum through the bile duct.
Bile salts are important for the metabolism of fat.
Endocrine gland:Produces vitamin A,
stores glycogen.
GALL BLADDERA small thin walled
green sac.Lies on the inferior
surface of the liver.Stores and
concentrates bile.Bile enters and leave
the gall bladder through the cystic duct.
PANCREASIt is a soft pink
triangular gland.It is retroperitoneal.It extends from the
spleen to the duodenum across the posterior abdominal wall.
Functions :1. Endocrine :
production of insulin and glucagon hormones.
2. Exocrine :It produces enzymes
that enter the duodenum through the pancreatic ducts.
PANCREATIC DUCTSMain pancreatic
duct: Joins the bile duct to form the Hepato pancreatic ampulla.
Both ducts open together through the duodenal papilla in the duodenum.
Accessory pancreatic duct:
Opens separately.