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Back to AI Flashcard MakerAnatomy and Physiology /Biology IB HL - D2 Digestion Part 4

Biology IB HL - D2 Digestion Part 4

Anatomy and Physiology24 CardsCreated about 1 month ago

This deck covers key concepts related to human digestion, focusing on cellulose digestion, dietary fiber, stomach ulcers, and cholera. It includes questions and answers on the role of bacteria in digestion, health benefits of fiber, and the mechanisms of diseases like ulcers and cholera.

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Why is cellulose indigestible for humans?

Humans lack the necessary enzymes to break down certain plant matter (e.g. lack cellulase required to digest cellulose)
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Key Terms

Term
Definition
Why is cellulose indigestible for humans?
Humans lack the necessary enzymes to break down certain plant matter (e.g. lack cellulase required to digest cellulose)
Why can certain herbivores digest cellulose?
Certain herbivores (ruminants) possess helpful bacteria in the digestive tract that can break down indigestible plant matter
What is fibre content positively correlated with?
The rate of transit of materials through the large intestine is positively correlated with their fibre content:
How does roughage help things in intestines move?
Roughage provides bulk in the intestines to help keep materials moving through the gut
What does roughage also help with?
Roughage also absorbs water, which keeps bowel movements soft and easy to pass
What are 3 health benefits of dietary fibre?
It reduces the frequency of constipation and lowers the risk of colon and rectal cancer It lowers blood cholesterol and regulates blood sugar levels (...
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Biology IB HL - D2 Digestion Part 4
TermDefinition
Why is cellulose indigestible for humans?
Humans lack the necessary enzymes to break down certain plant matter (e.g. lack cellulase required to digest cellulose)
Why can certain herbivores digest cellulose?
Certain herbivores (ruminants) possess helpful bacteria in the digestive tract that can break down indigestible plant matter
What is fibre content positively correlated with?
The rate of transit of materials through the large intestine is positively correlated with their fibre content:
How does roughage help things in intestines move?
Roughage provides bulk in the intestines to help keep materials moving through the gut
What does roughage also help with?
Roughage also absorbs water, which keeps bowel movements soft and easy to pass
What are 3 health benefits of dietary fibre?
It reduces the frequency of constipation and lowers the risk of colon and rectal cancer It lowers blood cholesterol and regulates blood sugar levels (by slowing the rate of absorption) It aids in weight management (contributes few calories despite consisting of a large volume of ingested material)
What happens to not absorbed materials?
Materials that are not absorbed by the small and large intestines are ultimately egested from the body as faeces
What does a large proportion of human faces consist of?
A large portion of human faeces consists of dietary fibre, such as cellulose and lignin Also present in faeces are the remains of intestinal epithelial cells, bile pigments and human flora (intestinal bacteria)
Mnemonic to help remember egested materials?
Bile pigments; Epithelial cells; Lignin; Cellulose; Human flora (bacteria); Mnemonic: BELCH
What are stomach ulcers?
Stomach ulcers are inflammed and damaged areas in the stomach wall, typically caused by exposure to gastric acids
What is (most likely) the cause of stomach ulcers?
there is a strong positive correlation between Helicobacter pylori infection and the development of stomach ulcers
What is helicobacter pylori?
Helicobacter pylori is a bacterium that can survive the acid conditions of the stomach by penetrating the mucus lining
Where do H. pylori attach to?
H. pylori anchors to the epithelial lining of the stomach, underneath the mucus lining
How does H. pylori begin damage to stomach?
An inflammatory immune response damages the epithelial cells of the stomach – including the mucus-secreting goblet cells
What does the prolonged inflammatory immune response lead to?
This results in the degradation of the protective mucus lining, exposing the stomach wall to gastric acids and causing ulcers
What can prolonged stomach ulcers cause?
The prolonged presence of stomach ulcers may lead to the development of stomach cancer over many years (20 – 30 years)
How can H.Pylori be treated?
H. pylori infections can be treated by antibiotics (previously, stomach ulcers were considered stress related and not treatable)
What is Vibrio cholerae?
Vibrio cholerae is a bacterial pathogen that infects the intestines and causes acute diarrhoea and dehydration
What disease is caused by vibrio cholerae?
The associated disease – cholera – can kill within hours unless treated with oral rehydration therapies
What is the first step of a cholera infection?
V. cholerae releases a toxin that binds to ganglioside receptors on the surface of intestinal epithelium cells
How does V. Cholerae enter the intestine?
This toxin is internalised by endocytosis and triggers the production of cyclic AMP (a second messenger) within the cell
What does cAMP cause?
Cyclic AMP (cAMP) activates specific ion channels within the cell membrane, causing an efflux of ions from the cell
How is an osmotic imbalance caused?
The build up of ions in the intestinal lumen draws water from cells and tissues via osmosis – causing acute diarrhoea
What is the final result of cholera?
As water is being removed from body tissues, dehydration will result if left untreated