Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Medsci142 Term 2 > Digestive System 3 > Flashcards

Digestive System 3 Flashcards

1
Q

What type of organ is the pancreas?

A

Dual-function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How is the pancreas an exocrine gland?

A

It manufactures the precursors of digestive enzymes and secreting then as alkaline “pancreatic juice” via a duct system leading to the duodenum; enzyme precursors are converted to their active form once they arrive in the duodenum. Most food substances are digested by pancreatic enzymes (proteins, carbohydrates, lipids and nucleic acids)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How is the pancreas an endocrine gland?

A

Islets of langerhans make up 1% of the pancreas and secrete hormones into the bloodstream. The hormones (insulin and glucagon) regulate blood glucose levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the trunk of the pancreas?

A

Main pancreatic duct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the small branch of the pancreas?

A

Interlobular ducts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the twigs of the pancreas?

A

Intercalated ducts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the leaves of the pancreas?

A

Acini (made up of serous type secretory cells)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Dimensions of the small intestine?

A

3 diameter, a little over 3m long

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What occurs in the small intestine?

A

Most digestion and absorption- at its upper end it receives exocrine secretions from the liver (ie bile, stored in the gallbladder) and pancreas (pancreatic juice, containing digestive enzyme precursors)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Three regions of the small intestine?

A

Duodenum (25cm long, c shaped tube, not suspended by mesentery, receives biliary and pancreatic ducts)
Jejenum (1m)
Ileum (2m)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Differences of the small intestine to the four layers of the gut?

A
  1. The mucosa is specialised to greatly increase the surface area available for secretion and absorption
  2. The submucosa just downstream of the pyloric spinchter contains mucous glands (glands of brunner)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Orders of increasing surface area in the small intestine?

A

Gross convolutions
Plicae
Villi
Microvilli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are plicae?

A

Circular folds 1cm high- each plica is covered with mucosa and has a core of submucosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the villi?

A

Fingers 1mm high. Covering is epithelium, core is lamina propria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are microvilli?

A

Fingers 1micrometre high. They form a “brush border” on the surface of individual absorptive cells. Each microvillus is covered with cell membrane and filled with cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What do columnar absorptive cells (enterocytes) do?

A

Absorb the small molecules resulting from digestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What do goblet cells do?

A

Secrete mucus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do enteroendocrine cells do?

A

Secrete hormone secretin (and others) into capillaries of the lamina propria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What do undifferentiated cells do?

A

They’re stem cells dividing to generate new epithelium

20
Q

What do paneth cells do?

A

Secrete bacterial enzyme lysozyme and are phagocytic

21
Q

What are venules in the submucosa tributaries of, and what travels through them?

A

Hepatic portal vein- transports carbohydrates (absorbed as monosaccharides), proteins (absorbed as amino acids), water and electrolytes

22
Q

What travels through lymphatic vessels of the small intestine?

A

Absorbed lipids

23
Q

What is the lifespan of the epithelium of the small intestine like?

A

Short-lived. Cell divisions occurs deep in the glands, then the entire sheet (except paneth cells) move slowly up the gland walls and up the sides of the villi. Old cells are shed from the villous tip. The entire journey lasts 5 days

24
Q

What is the lymph vessel within each villus like?

A

Lacteal

25
Q

What happens to the lymph in the small intestine?

A

It’s “milked” along the lacteal by contraction of smooth muscle fibres in the lamina propria which shorten the villus- these fibres arise from the muscularis mucosae

26
Q

What stimulates the release of secretin from enteroendocrine cells?

A

The arrival of acid chyme

27
Q

What does secretin in the bloodstream do?

A

Stimulates the release of pancreatic juices (cholecystokinin similar)

28
Q

What is also secreted by the enteroendocrine cells of the small intestine and stomach and what does it do?

A

Gastrin- stimulates gastric gland to secrete acid and enzymes

29
Q

Describe the small intestine?

A

A soft muscular tube about 1.5m long with 17 parts

30
Q

Functions of the large intestine?

A
  1. Absorption of salts and water (1 litre/day compared with 8litre/day absorbed in the small intestine)
  2. Conversion of chyme into faeces. Bacteria ferment remaining carbohydrates
  3. Bacteria produce some vitamins (B & k) which are absorbed
  4. Secretion of mucous to lubricate faeces
  5. Defecation
31
Q

Parts of the large intestine?

A
  1. Vermiform appendix
  2. Cecum
  3. Ascending colon
  4. Transverse colon
  5. Descending colon
  6. Sigmoid colon
  7. Rectum/anal canal/anus
32
Q

What controls intermittent flow of chyme from ileum into caecum?

A

Ileocecal valve

33
Q

What is the caecum like?

A

A dilated pouch (much larger in herbivores), where bacteria (not enzymes) are responsible for digestion. Humans produce no enzymes capable of digesting the cellulose of plants

34
Q

What is the appendix?

A

A vestigial worm-like appendage of the caecum

35
Q

What do faeces contain?

A

Bacteria (30%), undigested dietary fibre (30%), cells shed from the intestinal lining and mucus. Their colour is from pigments derived from bacterial decomposition of bilirubin

36
Q

What is the mucosa of the large intestine like?

A

No villi but many intestinal glands (also called crypts of lieberkuhn)
Surface epithelial cells are enterocytes (absorptive) similar to small intestine
Intestinal glands contain mostly goblet (mucous), no paneth cells
Cell renewal same as small intestine (entirely renewed every 4-5 days)
Many clusters of lymphocytes (lymphoid nodules) in the lamina propria, reflecting large bacterial content of colon

37
Q

What’s the external muscle of the large intestine like?

A

Outer longitudinal muscle is thickened in three strips. The strips (teniae coli) contract to pull the intestinal tube into sac like pockets (haustra coli). Haustra change shape and position

38
Q

What do columnar absorptive cells (enterocytes) do in the large intestine?

A

Absorb water

39
Q

What do goblet cells do in the large intestine?

A

Secrete mucus to lubricate the passage of faeces

40
Q

What do undifferentiated cells do in the large intestine?

A

Stem cells which divide to generate new epithelium

41
Q

What do white blood cells do in the large intestine?

A

Mostly lymphocytes which provide defence against bacteria invading from the lumen of the colon

42
Q

Describe the rectum?

A

Makes up final 20cm of the gut tube (last 2cm are the anal canal), the canal is closed by two sphincters

43
Q

What are the two sphincters of the rectum like?

A 
Internal= involuntary smooth muscle 
Outer= voluntary skeletal muscle
44
Q

When is there an urge to defecate?

A

When the rectum fills to 25% capacity

45
Q

What does stretching of the rectal wall do?

A

Initiates a reflex contraction of teniae coli in the descending colon and rectum. Shortening of this part if the gut tube further increases pressure in the rectum. The internal anal sphincter relaxes (opens) as part of the reflex

46
Q

What happens in regards to time and the external sphincter?

A

If convenient, it’s relaxed voluntarily, if not; maintained in contact reacted state and defecation reflex subsides (children take time to learn to control external spinchter)

Medsci142 Term 2 (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions