The anatomy and function of the GI tract

Question 1

what are the 4 main functions of the digestive tract/GI tract?

Answer 1

1. transport foodstuff
2. breakdown foodstuff
3. absorption of sugars, proteins, vitamins, minerals and water
4. excretion of wastes

Question 2

the digestive tract is simply a long muscular tube from the mouth (proximal) to anus/ rectum (most distal aspect)

what are the major sub-divisions of the GI?
what are the names of the accessory organs of the GI?

Answer 2

oral cavity/teeth/tongue, pharynx, oesophagus, stomach, SI, LI, anus

accessory organs= salivary glands, liver (makes plasma proteins, enzymes, and bile), gallbladder (secretes bile), pancreas

Question 3

the oesophagus pierces the diaphragm at which level?

Answer 3

T-10

Question 4

the mouth mechanically and chemically (enzymes/saliva) breaks down food and passes it to the oesophagus.

how does the oesophagus move food from mouth to the stomach?

Answer 4

it forms a bolus of food (a round ball). the oesophagus is made of SMOOTH muscle which will contract. this moves the bolus of food side to side and up and down–> moves it to the stomach

Question 5

describe the structure of the stomach

Answer 5

it is a muscular J-shaped bag.

on the inner surface it has muscular folds called ruggae = increase SA= increase speed of digestion

Question 6

what does stomach do to the food to break it down?

Answer 6

mechnically- churns the food like a washing machine so it goes from solid—> liquid.
chemically- via enzymes

the acidic env. is anti-microbial and will kill bacteria form food.

Question 7

describe the anatomy of the SI

Answer 7

divided into:

1. duodenum- this is the extension of tube from the stomach into the SI. most proximal.
2. jejunum- this is the middle which is all folded into villi= increase SA
3. ilium- also folded into villi. most distal and connect the SI to the LI.

Question 8

the human digestive tract has a mesentery. what is this?

Answer 8

messentery= double fold of the VISCERAL peritoneum (membrane).

it attaches organs to the body/ abdominal wall and allows them to be MOBILE so they can move freely.

Question 9

duodenum interacts with accessory organs which have ducts that empty here. which organs are these?

Answer 9

pancreas empties here

gallbladder empties bile here

Question 10

what is the function of bile being released into the duedeunum/ SI?

Answer 10

1. emulsifies fat

2. it increases pH to neutralise the acidic pH from stomach= E can work optimally

Question 11

large intestine can also be called the colon.

describe the anatomy of LI

Answer 11

from proximal to distal:

caecum
ascending colon
transverse colon
descending colon
sigmoid colon

Question 12

what is the function of the SI?

Answer 12

absorb nutrients

Question 13

what is the function of the LI?

Answer 13

absorb water,
form faecal matter,
secret mucus

Question 14

the pancreas structure is divided into head, neck, body and tail.

how does pancreas aid in digestion?

Answer 14

secrete enzymes into the duodeunum

secrete hormones: insulin and glucagon for blood sugar control

Question 15

what is the anatomy of the liver

Answer 15

it has 4 anatomical lobes:

right, left, quadrate and caudate lobes

Question 16

what is the function of the liver in digestion?

Answer 16

think of the liver as a organ that makes a lot of things:

• it makes bile
• it makes plasma proteins inclding albumin
• makes clotting factors
• stores glycogen

Question 17

what is the function of the gallbladder?

Answer 17

secrete bile into the duodenum which is made in the liver

Question 18

what is the portal triad?

Answer 18

3 main structures which take blood in and out of the liver. made of:

1. common bile duct
2. hepatic artery proper
3. hepatic portal vein

it is found on the free edge of the lesser omentum

Question 19

what is the peritoneum?

Answer 19

MEMBRANES of the abdomino-pelvic cavity

Question 20

what is the difference between the visceral and parietal periotineum?

Answer 20

visceral= membrane on the EXTERNAL surface of most digestive organs

parietal= membrane on the INNER body walls

Question 21

what is the peritoneal cavity?what fluid is it filled with?

Answer 21

it is the POTENTIAL space between the visceral and parietal membranes (only arises in disease/infection).

it is filled with the peritoneal fluid which allows organs to move

Question 22

an organ with a messentery is called…

Answer 22

an INTRA-PERITONEAL organ

Question 23

if the visceral peritoneum does not fold over, but rather it goes over the organ (like cling film fixing it in place), then it is IMMobile. that organ may also be called…

Answer 23

RETRO-peritoneal organs (behind the peritoneal)

e.g. kidneys

Question 24

the GREATER omentum covers the whole GI tract and stomach. how is omentum different from messentery?

Answer 24

omentum are a double layer of the PARIETAL periotoneum not the visceral

Question 25

where is the lesser omentum?

Answer 25

connected from the liver to the lesser curvature of the stomach