Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Alimentary System > Small Intestine Structure and Function > Flashcards

Small Intestine Structure and Function Flashcards

1
Q

how long is the duodenum?

A

25 cm long

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

What is the length of the small intestine?

A

About 6m

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

What does the small intestine consist of?

A

Duodenum

Jejunum

Ileum

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

What are some functions of the duodenum?

A

Gastric acid neutralisation

Digestion

Iron absorption

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

How long is the jejunum?

A

2.5m long (2/5 of total length)

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

What are some functions of the jejunum?

A

Nutrient absorption

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

What percentage of nutrient absorption occurs in the jejunum?

A

95%

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

How long is the ileum?

A

3.5m (3/5 total length)

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

What is the function of the ileum?

A

NaCl/H2O absorption

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

What is the absorptive surface of the small intestine enhanced by?

A

Folds, villi and microvilli

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

What are the circular folds of the small intestine called?

A

Plicae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the relative surface area increase of the small intestine due to plicae?

A

3

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

What is the relative surface area increase of the small intestine due to villi?

A

30

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

What is the relative surface area increase of the small intestine due to microvilli?

A

600

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

What is the classification of the epithelium in the small intestine?

A

Simple columnar

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

What does villus cells absorb?

A

NaCl

Monosaccharides

Amino acids

Peptides

Fats

Vitamins

Minerals

Water

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

What are the functions of crypt cells?

A

Secrete Cl and water

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

How much water does the small intestine secrete everyday?

A

1500ml

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

Where does the water that the small intestine secretes come from?

A

Epithelial cells lining the crypts of Lieberkuhn

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does the small intestine secrete water passively?

A

as a consequence of active secretion of chloride into intestinal lumen

21
Q

Why is H2O secretion important for normal digestive processes?

A

Maintains lumenal contents in liquid state

Promotes mixing of nutrients with digestive enzymes

Aids nutrient presentation to absorbing surface

Dilutes and washes away potentially injurious substances

22
Q

What happens to H2O secreted by crypts?

A

Normally H2O secreted by crypts reabsorbed by villi

23
Q

What are the 2 distinct kinds of movements that makes up intestinal motility?

A

segmentation
peristalsis

24
Q

What is segmentation?

A

occurs when the intestine divides into many sections due to simultaneous transient contractions, and when these contractions subside, contractions appear more or less at the sites in between the original contractions giving a checkered appearance.

Contraction ⇔ relaxation of short intestinal segments
Contraction (few seconds) moves chyme (up & down) into adjacent areas of relaxation
Relaxed areas then contract and push chyme back

25
When is segmentation most common?
most common during a meal
26
What is the function of segmentation?
Provides thorough mixing of contents with digestive enzymes Brings chyme into contact with absorbing surface
27
How long does each cycle of segmentation last?
few seconds
28
Explain the mechanism of segmentation contractions?
Initiated by depolarisation generated by pacemaker cells in longitudinal muscle layer (cf gastric motility) Intestinal basic electrical rhythm (BER) produces oscillations in membrane potential ⇒ threshold ⇒ action potential ⇒ contraction Action potential frequency determines strength of contraction Frequency of segmentation determined by BER
29
What is BER?
The basal or basic electrical rhythm (BER) or electrical control activity (ECA) is the spontaneous depolarization and repolarization of pacemaker cells known as interstitial cells of Cajal (ICCs) in the smooth muscle of the stomach, small intestine, and large intestine.
30
What determins the strength of contraction for segmentation?
Action potential frequency determines strength of contraction
31
What is frequency of segmentation determined by?
Frequency of segmentation determined by BER
32
How does BER change as chyme moves down the intestine to the rectum?
BER decreases as move down intestine → rectum
33
What supplies the innervation for segmentation?
Parasympathetic NS (vagus) ⇒ ↑ contraction Sympathetic NS ⇒ ↓ contraction No effect of autonomic nervous system on BER
34
Does the autonomic nervous system have an effect on BER?
no effect
35
What effect does the parasympathetic nervous system have on segmentation?
↑ contraction
36
What effect does the sympathetic nervous system have on segmentation?
↓ contraction
37
What does segmentation cause?
Following absorption of nutrients: segmentation stops, and peristalsis starts
38
What occurs following absorption of nutrients in terms of segmentation and peristalsis?
Migrating Motility Complex (MMC)
39
What are the pattern of contractions that creates peristalsis known as?
Migrating Motility Complex (MMC)
40
Explain the mechanism of peristalsis?
Pattern of peristaltic activity travelling down small intestine (starts in gastric antrum) As one MMC ends (terminal ileum) another begins Arrival of food in stomach ⇒ cessation of MMC and initiation of segmentation
41
Where does peristalsis begin and end?
gastric antrum terminal ileum
42
How does the arrival of food into the stomach impact segmentation and peristalsis?
cessation of MMC and initiation of segmentation
43
What is the function of peristalsis?
Move undigested material into large intestine Limit bacterial colonisation of small intestine
44
What is a hormone involved in the initiation of MMC?
Motilin (hormone) involved in initiation of MMC
45
What happens when intestinal smooth muscle is distended such as due to chyme?
If intestinal smooth muscle is distended (eg by bolus of chyme): Muscle on oral side of bolus contracts Muscle on anal side of bolus relaxes Bolus is moved into area of relaxation towards colon Mediated by neurones in myenteric plexus
46
What is the bolus moving towards the colon mediated by?
neurones in myenteric plexus
47
Explain the mechanism of the gastroileal reflex?
Gastric emptying ⇒ ↑ segmentation activity in ileum Opening of ileocaecal valve (sphincter) Entry of chyme into large intestine Distension of colon Reflex contraction of ileocaecal sphincter (prevents backflux into small intestine)
48
What reflex controls chyme entering the large intestine?
Gastroileal Reflex

Alimentary System (44 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions