Order the events in peristalsis.
Reveal answer
- circular muscle behind bolus contracts
- muscle in front relaxes
- bolus pushed forward
- wave of contraction moves along
Key words: circular muscle
2(e) NUTRITION · RECALL
2.28 Peristalsis
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What is peristalsis?
Reveal answer
Waves of muscle contraction in the gut wall that push food along.
Key words: muscle · contraction
Does gravity move food down the oesophagus?
Reveal answer
No. Peristalsis pushes it, which is why you can swallow lying down.
Key words: peristalsis
What is meant by the term peristalsis?
Reveal answer
Coordinated muscular waves moving contents along the alimentary canal.
Key words: peristalsis
What is meant by the term circular muscle?
Reveal answer
Muscle arranged around the gut that narrows the lumen when contracted.
Key words: circular muscle
What is meant by the term longitudinal muscle?
Reveal answer
Muscle arranged along the gut that shortens a section when contracted.
Key words: longitudinal muscle
What is meant by the term bolus?
Reveal answer
A lubricated mass of chewed food that has been swallowed.
Key words: bolus
What is meant by the term sphincter?
Reveal answer
A ring of muscle controlling passage between regions.
Key words: sphincter
Muscle actions during a wave, Circular muscle behind contracts. Effect on lumen? Consequence?
Reveal answer
Effect on lumen: Lumen narrows. Consequence: Pushes bolus forward.
Key words: Circular muscle behind contracts
Muscle actions during a wave, Circular muscle ahead relaxes. Effect on lumen? Consequence?
Reveal answer
Effect on lumen: Lumen remains open. Consequence: Allows bolus to enter.
Key words: Circular muscle ahead relaxes
Muscle actions during a wave, Longitudinal muscle ahead contracts. Effect on lumen? Consequence?
Reveal answer
Effect on lumen: Section shortens/widens. Consequence: Helps receive and advance bolus.
Key words: Longitudinal muscle ahead contracts
Muscle actions during a wave, Sphincter contracts. Effect on lumen? Consequence?
Reveal answer
Effect on lumen: Passage closes. Consequence: Controls regional flow.
Key words: Sphincter contracts
True or false, and why? “Gravity moves food down the oesophagus.”
Reveal answer
False. Peristalsis actively propels it and can work against gravity.
True or false, and why? “Muscles in front of the bolus contract shut.”
Reveal answer
False. The region ahead relaxes or widens to receive it.
True or false, and why? “Peristalsis occurs only in the oesophagus.”
Reveal answer
False. Coordinated movements occur throughout much of the alimentary canal.