Peritoneum

Question 1

Definition

Answer 1

Smooth shiny serous membrane that:
1. Lines the abdomen and pelvic cavities
2. Covers abdominal and pelvic organs for variable degrees

Question 2

Peritoneal sac

Answer 2

Large serous sac formed by peritoneal membrane containing peritoneal cavity which is empty except for thin film of serous fluid

Question 3

Formation

Answer 3

1. During intrauterine life, peritoneal sac develop from mesoderm as closed sac which lines abdominal cavity
2. Abdominal organ develop and grow on posterior abdominal wall outside peritoneal sac then the bulge forwards to invaginate sac

Question 4

Invagination degree of abdominal organs is variable:

Answer 4

1. Some organs leave posterior abdominal wall completely and is suspended by peritoneal fold
   - mesentery (in intestine)
   - omentum (in stomach)
   - ligament (as in spleen and liver)
2. Some other organs may bulge into peritoneal cavity to limited extent:
   Covered in peritoneum on fronts and sides only as in:
   - kidneys
   - pancreas
   - ascending colon
   - descending colon

Question 5

As a result of invagination, peritoneum becomes differentiated into:

Answer 5

1. Visceral layer
2. Parietal layer

Question 6

Visceral layer

Answer 6

1. Covered abdominal organs
2. Supplied by autonomic nerves and insensitive to pain but sensitive for stretch

Question 7

Parietal layer

Answer 7

1. Lines abdominal wall but separated from it by Extraperitoneal tissue
2. Supplied by somatic nerves so very sensitive and its irritation leads to pain, tenderness, and rigidity

Question 8

Peritoneal cavity

Answer 8

1. Lies in between visceral and parietal layers
2. All abdominal organs whether suspended by mesentery or not lie outside peritoneal cavity which remain empty cavity except for thin film of peritoneal fluid

Question 9

Sex differences

Answer 9

1. Male: peritoneal cavity is a closed sac
2. Female: receives uterine tubes opening communicating it with outside

Question 10

Functions

Answer 10

1. Provides smooth surface for viscera to move freely
2. Secretes peritoneal fluid containing antibodies to prevent infection
3. Its mesothelial cells can transform into fibroblasts allowing abdominal wounds rapid healing
4. Greater omentum tends to surround structures in case of infection, localizing infection spread (abdomen policeman)
5. Fat storage as in greater omentum