Small Intestine Structure and Function Flashcards

1
Q

What is the function of the duodenum?

A

Gastric Acid Neutralisation, Iron Absorption and Digestion

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2
Q

What is the function of the jejunum?

A

Nutrient absorption

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3
Q

What is the function of the ileum?

A

NaCl/H2O Absorption –> Chyme dehydration

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4
Q

Describe the basic electrical rhythm

A

Is initiated by depol generated by pacemaker cells in the longitudinal muscle layer. The intestinal BER produces oscillations in membrane potential which will eventually reach threshold, generate an AP which will initiate contraction

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5
Q

What determines the strength of contraction?

A

The frequency of the action potential

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6
Q

What determines the frequency of segmentation?

A

BER

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7
Q

What happens to BER as we move from intestine to rectum?

A

BER decreases

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8
Q

Describe segmentation

A

Contraction and relaxation of short intestinal segments. Contraction moves chyme into areas of relaxation. Relaxed areas contract and push chyme back.

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9
Q

What is the function of segmentation?

A

This process mixes chyme with digestive enzymes and brings chyme into contact with the absorbing surface

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10
Q

When does segmentation occur?

A

During a meal

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11
Q

When does peristalsis occur?

A

After segmentation

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12
Q

Where does peristalsis begin and end?

A

Antrum of stomach to terminal ileum

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13
Q

What initiates an MMC?

A

Motilin

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14
Q

What is the effect of vagus stimulation on contraction?

A

Contraction increases

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15
Q

What is the effect of sympathetic stimulation on contraction?

A

Contraction decreases

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16
Q

What do villi cells absorb?

A

NaCl, monosaccharides, amino acids, peptides, fats, vitamins, minerals, water

17
Q

What do crypt cells secrete?

A

Cl and Water

18
Q

What is the function of H2O in the digestive process?

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

19
Q

Where is H2O reabsorbed in the digestive system?

A

By Villi

20
Q

What is the law of the intestine?

A

Muscle on oral side of bolus contracts, muscle on anal side of bolus relaxes. Bolus is moved into area of relaxation towards colon

21
Q

Describe the gastroileal reflex

A

Gastric emptying= increased segmentation activity in ileum. Ileocaecal valve opens, chyme enters large intestine, colon distends and reflex contraction of ileocaecal sphincter prevents back-flux into small intestine