Functional Anatomy and General Principles Flashcards Preview

FHB Block 3 > Functional Anatomy and General Principles > Flashcards

Flashcards in Functional Anatomy and General Principles Deck (49):
1

What is the sphincter of oddi?

The sphincter between the common bile duct/pancreatic duct and the duodenum. It controls the amount of bile and pancreatic juices released into the duodenum

2

What are the three major arteries of the splanchnic circulation?

Celiac, SMA and IMA

3

What organs are supplied by the celiac artery?

Liver, spleen and stomach

4

What organs are supplied by the Superior mesenteric artery?

Pancreas, small intestine and proximal colon

5

What organs are supplied by the IMA?

Distal colon

6

What happens to large molecules that are too large to pass into capillaries?

They are taken up by the lymphatic system and returned to the systemic circulation through thoracic duct --> subclavian vein

7

Name the four layers of the gut wall from inside to outside

Mucosa, Submucosa, muscularis externa, serosa

8

What individual components make up the mucosa of the gut wall?

Mucosa is the innermost layer. It is made up of epithelium, the lamina propria, and the muscularis mucosae

9

What are absorptive enterocytes?

The are the most abundant cell of the GI tract epithelium. They play a vital role in digestion and absorption

10

What is produced in gastric mucosal cells?

Protons

11

What type of cells are found in the mucosal epithelium of the esophagus?

Squamous cells- they help in the transportation of swallowed food

12

What type of cells are found in the mucosal epithelium of the intestine?

Columnar- helps in absorption or selective uptake of nutrients, ions, water

13

Describe the architecture of the small intestinal epithelium

The surface area of the small intestinal epithelium consists of villi and crypts.

14

What is the average life span of a cell at the villus tip in the GI tract?

3-5 days. The epithelial lining of the GI tracts is continously renewed

15

What is the consequence of a reduced surface area in the intestinal epithelium, such as in celiac disease?

Malabsorption

16

What is the lamina propria?

The layer immediately below the epithelium- it consists of loose connective tissue (collagen and elastin fibrils).

It is rich in glands, contains lymph vessels and nodes, capillaries, nerve fibers.

17

What three layers make up the mucosa?

Epithelium, lamina propria, and the muscularis mucosa

18

What is the muscularis mucosae?

This this layer of smooth muscle cells directly below the lamina propria

19

In what layer of the GI tract is the submucosal plexus of the enteric nervous system found?

The submucosae

20

In what layer of the GI tract is the myenteric plexus of the enteric nervous system found?

Between the two layers of the muscularis externa (muscularis propria)

21

Describe the muscularis externa

It consists of two layers of smooth muscle cells:

Inner circular layer
Outer longitudinal layer

Responsible for mixing and propelling contexts of the GI tract

22

What is the outermost layer of the GI tract?

The Serosa

23

What cell type makes up the serosa?

Squamous mesothelial cells- secretes a viscous fluid in order to reduce friction between organs in the abdominal cavity

24

Which are the "sensor cells" of the GI system?

Enteroendocrine cells- they respond to a stimulus by secreting a peptide or hormone

25

Which are target cells of paracrine regulation?

smooth muscle, absorptive enterocytes, secretory cells in glands and other EECs

26

Enterochromaffin-like cells in the stomach release what hormone? What is the effect?

Histamine. When released, the histamine binds to nearby parietal cells which can then release HCl

27

What is the role of serotonin released in the GI tract?

Regulation of smooth muscle contractility in the GI

28

What cells release serotonin?

Enteric neurons, mucosal mast cells and enterochromaffin cells

29

When and where is cholecystokinin released?

Cholecystokinin is released from the I cells in duodenum in response to dietary protein and fatty acids

30

What is celiac disease?

Allergic response to gliadin, a component of gluten. It causes an inflammatory response which results in a reduction of density and length of microvilli

31

Differentiate the extrinsic from the intrinsic nervous system in the gut

Extrinsic: nerves that innervate the gut, with cell bodies outside of the gut wall- part of the ANS (parasympathetic and sympathetic)

Intrinsic: The enteric nervous system- includes the submucosal and myenteric plexus

32

What parts of the gut does the vagus nerve innervate?

Everything except for the distal colon and anorectal region

(Esophagus, stomach, gallbladder, pancreas, 1st part of the intestine, cecum, proximal part of the colon)

33

Describe the general impact of parasympathetic stimulation on GI function

Activation

34

What two neurotransmitters are released by peptidergic neurons?

Substance P and VIP

35

What are vagovagal reflexes?

Both afferent and efferent fibers of the vagus nerve coordinate responses to gut stimuli

36

Which gut muscles are activated by sympathetic innervation?

GI sphincter muscles

37

Differentiate how the parasympathetic and sympathetic nerves interact with the ENS.

Parasympathetic fibers all affect the gut indirectly, through synapsing on the ENS

Sympathetic fibers can either directly stimulate cells, or indirectly through stimulation of the ENS

38

Where is the myenteric plexus?

Between the inner circular and outer longitudinal muscle layer (muscularis externae)

39

Where is the submucosal plexus?

In the submucosal layer of the gut wall

40

Is the ENS autonomous?

The ENS can act autonomously, but also receives information from the ANS

41

Is all of the muscle of the GI tract smooth muscle?

No- the pharynx, upper 1/3 of the esophagus and the external anal sphincter are striated muscle

42

What permits rapid cell-cell spread of action potentials in GI smooth muscle?

Gap Junctions formed with interstitial cells of Cajal (ICC's)

43

Differentiate phasic from tonic conctractions

Phasic: periodic contractions followed by relaxation

Tonic: Constant level of contraction- generally found in sphincters that only relax when told to do so

44

Which cells act as the pacemaker for the gut?

Interstitial cells of cajal- ICCs: They generate the slow waves.

45

How do slow waves of the GI tract relate to contraction?

Slow waves that do not reach threshold still lead to tonic contractions. When action potentials occur, it is followed by a much stronger phasic contraction

46

Where do segmentation contractions occur?

Predominantly in the small and large intestines

47

What is the purpose of segmental contractions?

These allow mixing of the luminal contents with GI tract secretions and increase exposure to the mucosal surfaces where absorption occurs

48

Which neurotransmitters are involved in orad contraction of peristalsis?

ACh and substance P

49

Which neurotransmitters are involved in caudad relaxation of peristalsis?

VIP and NO