3.1 GI general anatomy

Question 1

what are the 6 essential activities of the digestive process

Answer 1

1. ingestion
2. Mechanical breakdown (chewing in mouth, churing in stomach, segmentation in small intestine)
3. Chemical digestion
4. Propulsion (swallowing in oropharynx, peristalsis in esophagus, stomach, SI and LI)
5. Absorption (begins in stomach but most is in SI)
6. Defecation

Question 2

What are the 2 groups of organs in the digestive system?

Answer 2

1. Alimentary Canal (gastrointestinal tract)
   
   • oral cavity, teeth, tongue
   • pharynx
   • esophagus
   • stomach
   • small intestine
   • large intestine (colon)
2. Accessory organs
   
   • salivary glands
   • liver
   • gallbladder
   • pancreas

Question 3

what organs are located in the right hypochodriac region

Answer 3

liber and gallbladder

Question 4

what organs are found in the epigastric region

Answer 4

liver and stomach

Question 5

what organs are found in the left hypochondriax region

Answer 5

iaphragm and stomach

Question 6

what organs are found in the right lumbar region

Answer 6

ascending colon

*draw fram around torso with right hand, first go up thats ascening

Question 7

what organs are in the ubilical region

Answer 7

small intestine and transverse colon

Question 8

what organs are found in the left lumbar region

Answer 8

descending colon

Question 9

what organs are found in the right illiac (inguinal) region

Answer 9

cecum and appendix

Question 10

what organs are found in the hypogastric (pubic) region

Answer 10

urinary bladder

Question 11

what organs are found in the left iliac (inguinal) region

Answer 11

sigmoid colon

Question 12

what are teh 4 basic layers in the alimentary canal

Answer 12

1. muscsa (touches the food most deep)
2. submucosa
3. muscularis externa (smooth muscle layer)
4. Serosa/adventitia

Question 13

describe the parts of the mucosa layer

Answer 13

1. epithelium
   
   • stratified squamous (to resist abrasion) or simple columnar (somtimes goblet to absorb or secrete -> if goblet it produces mucus)
2. Lamina propria
   
   • loose connective tissue
   • capillaries for nourishment & absorption
   • lymphoid follicles MALT (potential to ingest pathogens need to be able to fight off)
3. Muscularis mucosae
   
   • smooth uscle (moves mucosa)
   • not propelling food stuff

Question 14

what are the functions of the mucosa

Answer 14

• secretes mucus, digestive enzymes and hormones
• absorbed end products of digestion
• protects againt infectious disease

Question 15

describe the submucosa

Answer 15

*second layer sep by smooth muscle layer

• loose connective tissue

has blood & lymphatic vessels, lymphoid follicles, gland and submucosal nerve plexus

Question 16

describe the functoins of the submucosa

Answer 16

support mucosa

bidns layers together

Question 17

describe the layers of the muscularis externa

Answer 17

• circular layer: smoth muscle (squeezes
• outer longitudinal layer: smooth muscle (will shorten)
• myenteric nerve plexus: autonomic nerves -> coordinates movment of 2 smooth muscle layers
• some alters are more thick (sphincter) controls release and prevents backflow

Question 18

what are the functions of the muscularis externa

Answer 18

• segmentation & peristalsis
• sometimes forms sphincters to control passave/prevent backflow

Question 19

describe peristalsis

Answer 19

*physically moves food stuff trhu body

1. bolus of food arrives in digestive system
2. circular muscles contract behind bolus
3. longitudinal muscles ahdead of bolus contract
4. contraction in circular muscle layer forces bolus forward

Question 20

describe segmentation

Answer 20

*helps with mixing -> contract and relax, not moving food

• non adjacent segemtns of alimentary tract organs alternatively sontract & relax
• mvoes food forward then backward for food mixing -> slow food propulsion occurs

*like cat making biscutis -> alternative sections like alternating paws

Question 21

describe the Serosa

Answer 21

aka visceral peritoneum

• composed of loose connective tissue and epithelium (mesothelium -> simple squamous)

* Retroperitoneal organs have an adventitia: Dense irregular CT to bind organs together

Question 22

what is the fucntion of serosa

Answer 22

permit mobility

* when see adventita have dense connective tissue that holds things in place

*serosa is double mem epithelium, surrounds organs within abdominal cavity

Question 23

what is the peritonal cavity? waht lines it?

Answer 23

Peritoneal cavity = Between visceral & parietal peritoneum; fluid lubricates mobile organs

Visceral peritoneum: on external surface or organs

Parietal peritonium: lines body wall (permiter)

Question 24

what surrounds intraperitoneal organs?

describe it

what are intraperitonal organs?

Answer 24

Intraperitonal organs = liver, stomach, ileum, jejunum, transverse colon, sigmoid colon

surrounded by peritoneum (these organs pushed their way into the body cavity)

• have a mesentery: double layer of peritoneum
• > route for blood vessels, lymphatics and nerves
• > holds organs in place and stores fat

Question 25

what are the retroperitoneal organs? deacribe what surrounds them

Answer 25

retroperitoneal organs: duodenum (almsot all of it), ascending colon, descening colon, rectum, pancreas NO MESENTARY -\> is resorbed and lost - these organs are POSTERIOR to peritoneum 0 have an adventitia

Question 26

attachment/placement of mesenteries

Answer 26

start: ant abdominal wall - \> **Falcifrom ligament:** anterior liver - anterior ab wall (attaches liver to the udnerside of the diaphagm - \> **lesser omentum:** liver - lesser curvature of stomach - \> **Greater omentum:** greater curvature of stomach -\> anterior transverse colon - \> **transverse mesocolon:** attaches transverse colon to post ab wall \*have viseral peritonem (lines organs aka cerosa) and parietal peritoneum (lines body cavity

Question 27

what is diff about the greater omentum

Answer 27

- has layers: 2 folding back on itelsef (attaches greater curvature of stoamch and anterior transverse colon

Question 28

describe enteric nervous system what are the 2 main parts

Answer 28

- Intrinsic nerve supply of alimentary canal - Linked to CNS via afferent visceral fibers - Long ANS fibers synapse with enteric plexuses main pats are **Myenteric nerve plexus:** controls GI tract motility **Submucosal nerve pluxus:** regulates glands and smoth muscle (inc BC) in mucosa

Question 29

what are the 3 mechanisms to regulate and control digestive activities

Answer 29

local factors, neural control and hormonal control

Question 30

describe local factors for the regulation and cotnrol of digestive activities

Answer 30

-Primary stimulus for digestive activities including: lumen pH physical distortion presence of chemicals (nutrients/chemical messengers)

Question 31

describe neural control for regulation and control of digestive activities

Answer 31

* Short relfexes * triggered by chemoreceptors/stretch receptors in Gi tract walls * controls myenteric plexus * Long reflexes * involves interneurons and motor neurons in CNS providing higher level control over digestive and glangular activities * generally controled my large peristaltic waves (move stuff thru body for cooridnated activitiy)

Question 32

describe hormonal control for regulation and control of digestive activities

Answer 32

- GI tract prpdicts many hormones produced by enteroendocrine cells (in gidestive tract epithelium)