Chapter 32- Digestive System

what is the digestive system?

system of the body concerned with:

-breakdown of food

-absorption of nutrients

what is the digestive system also referred to as?

-Digestive tract

-Gastrointestinal tract

-Alimentary canal

what do the organs of the digestive system exist as?

a continuous tube: extending from ORAL CAVITY to the ANUS

what lines the majority of the digestive tract?

enteric nervous system in a web-like fashion

what is the enteric nervous system apart of?

autonomic nervous system

what is the peritoneum?

a large, highly folded, serous membrane located in the abdomen

what is the parietal peritoneum?

portion of the peritoneum that lines the inner surface of the abdominal wall

what is the visceral peritoneum?

portion of peritoneum located on the surfaces of the organs of the abdomen

what is the cavity between visceral and parietal layers called?

peritoneal cavity

what is the peritoneal cavity?

potential space filled with a thin film of fluid

how many sacs is the peritoneal cavity divided into? what are they?

2; greater sac and lesser sac (omental bursa)

what is the greater sac?

main portion of the peritoneal cavity

where is the greater sac located?

extends from the diaphragm to the pelvic floor; from the anterior abdominal wall to the posterior abdominal wall

what is the lesser sac (omental bursa) ?

smaller portion of the peritoneal cavity

where is the lesser sac located?

posterior to the stomach; extends upward behind the liver and downward into the greater omentum

what is the only opening between the greater and lesser sac?

epiploic foramen of Winslow

what is the epiploic foramen of Winslow bounded by?

PDIL

-portal vein, hepatic artery proper, bile duct (in lesser omentum)

-duodenum= inferiorly

-inferior vena cava= posteriorly

-liver= superiorly

what are peritoneal folds/membranes?

reflections of visceral peritoneum

-falciform ligament

-greater omentum

-lesser omentum

-mesentery (mesentery proper)

-transverse mesocolon

-sigmoid mesocolon

where does the falciform ligament extend?

liver to the anterior abdominal wall

what does the falciform ligament contain in its free edge?

round ligament of the liver (obliterated umbilical vein)

where does the greater omentum extend?

from the greater curvature of the stomach to the TRANSVERSE colon

what does the greater omentum form?

forms a fatty apron OVER the small intestines

where does the lesser omentum extend?

from the lesser curvature of the stomach to the liver

what does the lesser omentum contain in its right free edge?

-portal vein

-hepatic artery proper

-bile duct

what does the mesentery (mesentery proper) do?

supports and suspends the jejunum and ileum from the posterior abdominal wall

what does the transverse mesocolon do?

suspends the transverse colon from posterior abdominal wall

what does the sigmoid mesocolon do?

suspends the sigmoid colon from posterior abdominal wall

what are the structures located behind the peritoneum directly on the posterior wall collectively called?

Retroperitoneal structures

what are the retroperitoneal structures?

DADPKA

1. Duodenum

2. Ascending colon

3. Descending colon

4. Pancreas

5. Kidney and ureter

6. Aorta and inferior vena cava

what are the structures of the digestive system?

1. oral cavity

2. pharynx

3. esophagus

4. stomach

5. small intestine

6. ileocecal junction

7. Rectum

8. Anus

what is the oral cavity also referred to as? what does it contain?

-mouth

-tongue, teeth, openings of the salivary glands

what is the tongue?

a skeletal muscular organ

what does the tongue function in?

-sense of taste

-mastication

-movement of food

how many teeth do adults have?

32

what are the types of teeth?

incisors, canines, premolars, molars

how many pairs of salivary glands are there? what are they?

3 pairs

-parotid gland

-submandibular gland

-sublingual gland

what kinds of glands are salivary glands? what do they empty?

-exocrine glands- since they are drained by a duct

-they all empty the gland secretions (SALIVA) into the oral cavity

where is the parotid gland located? where is it drained?

just below the ear; drained by the parotid DUCT

where is the submandibular gland located? where is it drained?

just below the mandible; drained by the submandibular DUCT--> this gland used to be called the submaxillary gland

where is the sublingual gland located? where is it drained?

just below the tongue; drained by the sublingual DUCT

what is the pharynx composed of?

skeletal muscle

what is pharynx function?

swallowing

how many parts is the pharynx divided into? what are they?

-3 parts: nasopharynx, oropharynx, laryngopharnyx/hypopharynx

where is the nasopharynx located?

posterior to nasal cavity

Where is the oropharynx located?

posterior to oral cavity

where is the laryngopharynx/hypopharynx located?

posterior to the larynx

what is the laryngopharynx/hypopharynx continuous with?

esophagus

-what is the esophagus?

-where does it extend from?

-muscular tube

-extending 25 cm from the lower end of the pharynx (CV6) to the cardiac opening of the stomach (TV11) inferiorly

what are the 3 regional parts of the esophagus?

1. cervical

2. thoracic

3. abdominal

where is the cervical part?

in the neck and lies posterior to the trachea

where is the thoracic part?

in the thorax and lies posterior to the trachea in the upper half and posterior to the heart in the lower half

what happens to the abdominal part after piercing the diaphragm at the esophageal opening of the diaphragm?

it enters the abdomen

where does the abdominal part run? where is it terminated?

a short course in the abdomen and terminated by joining the stomach at the gastroesophageal junction

where does arterial supply of the esophagus come from?

1. Esophageal and bronchial branches (aorta)

2. Inferior thyroid (thyrocervical trunk and subclavian artery) = SUPERIORLY

3. Esophageal branches of the left gastric (celiac trunk) = INFERIORLY

what is the stomach?

a digestive organ that is responsible for the storage of food

what are the 3 parts of the stomach?

1. Fundus

2. Body

3. Pyloric part

what is the fundus of the stomach?

a part of stomach ABOVE the level of entrance of the esophagus

what is the body of the stomach?

comprises the main mass of the stomach

where is the body located?

between fundus and pyloric part of the stomach

where is the pyloric part of stomach? where does it end?

extends toward the right from the lower part of the body of the stomach and it ends at the pyloric opening

what is the pyloric opening surrounded by?

a circular smooth muscle called the PYLORIC SPHINCTER

what is the pyloric opening?

opening between stomach and first part of duodenum

what are the 2 curvatures of the stomach?

greater curvature and lesser curvature

-what is the greater curvature?

-what is its shape?

-margin of the stomach that courses OVER THE FUNDUS and INFERIORLY on the LEFT side of the stomach to the INFERIOR side of PYLORIS

-it is a CONVEX curve in its entirety

what attaches to the greater curvature?

greater omentum

where is the greater omentum located?

between (greater curvature of) STOMACH and TRANSVERSE COLON

-what is the lesser curvature?

-what is its shape?

margin located on the RIGHT side of stomach

its curvature is CONCAVE

what is attached to the lesser curvature?

LESSER OMENTUM

what are the lesser and greater omentum compromised of?

Connective structure that is embedded with fat

where is the lesser omentum located?

between (lesser curvature of) stomach and liver

what are the 2 openings of the stomach?

cardiac opening and pyloric opening

where is the cardiac opening located/lies?

-lies BETWEEN cavity of esophagus and cavity of stomach

-located at the upper junction of the greater and lesser curvatures

why is the cardiac opening called cardiac?

bc of its close relationship with the part of the diaphragm in which the heart rests

where is the pyloric opening located?

between stomach and first part of duodenum

what surrounds the pyloric opening?

pyloric sphincter= circular smooth muscle

what does the internal surface of the stomach present?

folds= RUGAE

where is the arterial supply of the stomach from?

-right and left gastric arteries

-short gastric artery

-right and left gastroepiploic arteries

what is the small intestine?

part of intestine between pyloric sphincter (connected to stomach) and ileocecal junction (where it joins the large intestine)

how long is the small intestine? what about its diameter?

- 7 m

- its diameter gradually DIMINISHES through its length

what are the 3 parts of the small intestine?

duodenum, jejunum, ileum

what is the first part of the small intestine? where does it extend?

duodenum

- extends from pyloric sphincter to where it joins the jejunum

what shape is the duodenum?

C-shaped and has a concave medial border

what does the concave medial border of the duodenum receive?

openings of ducts draining liver, gall bladder, and pancreas

what are the 4 parts of the duodenum?

1. 1st/ superior

2. 2nd/ descending

3. 3rd/ horizontal

4. 4th/ ascending

what does the 2nd/descending part of duodenum do?

receives bile and pancreatic juices

what does the 4th/ascending part of the duodenum do?

course UPWARD to the suspensory ligament of Treitz where it leads to the duodenojejunal flexure

where is the arterial supply to the duodenum from?

pancreaticoduodenal arteries

where do the pancreaticoduodenal arteries arise from?

gastroduodenal and superior mesenteric arteries

what is the jejunum?

proximal 2/5 of remainder of small intestine

what is the jejunum supplied by?

jejunal branches of the superior mesenteric artery

what is the ileum?

distal 3/5 of remainder of small intestine

what supplies the ileum?

ileal branches

where do the ileal branches arise from?

both the superior mesenteric artery and ilelocolic artery

does a morphological line of demarcation exist between the jejunum and ileum?

no

what are jejunum and ileum? what are they suspended by?

-highy coiled structures

-suspended by the mesentery (mesentery proper) --> supports and suspends the ileum and jejunum from the posterior abdominal wall

what is the ileocecal junction?

junction of the ileum portion of small intestine to cecum portion of large intestine

what is the ileocecal opening?

opening between the lumen of ileum and lumen of cecum

what is the ileocecal opening guarded by?

ileocecal valve

where is the large intestine/colon?

extends from the ileocecal junction to the anus

what are the parts of the large intestine?

1. cecum

2. vermiform appendix

3. ascending colon

4. transverse colon

5. descending colon

6. sigmoid colon