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D2 Digestion
IB Syllabus
14
Biology
11th Grade
05/22/2015

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Term
Why is the digestive system not constantly active?
Definition
To preserve energy because there are gaps between meals.
Term
What are the bodies' responses to the sight and smell of food
Definition
brain sends nerve impulses via the vagus nerve from the medulla in the brain. Gland cells in stomach wall secrete gastric juice. If chemoreceptors in the stomach wall detect peptides in the food impulses are sent to the brain.
Term
What is the function of the endoplasmic reticulum
Definition
to synthesize proteins.
Term
define peristalsis
Definition
a sequential series of smooth muscle contractions that pushes food through the digestive system.
Term
What are the components of the gastric juice in the stomach?
Definition
Hydrochloric acid, Pepsin, mucus
Term
What is the function of hydrochloric acid in the stomach?
Definition
denatures proteins and kills the numerous pathogens that enter the body in food and water.
Term
What is the function of pepsin in the stomach?
Definition
active form pepsinogen, this ensures that the cells that produce pepsinogen are not digested as protein.
Term
What is the function of mucus in the stomach
Definition
It lines the inside of the stomach wall to prevent stomach damage from the hydrochloric acid.
Term
What are hydrochloric acid, pepsin and mucus secreted from?
Definition
HCl = parietal cells
Pep = the chief cells as the inactive pepsinogen.
Muc = goblet cells
Term
Why are the acid conditions in the stomach useful for?
Definition
favor some hydrolysis reactions and help to control pathogens in ingested food
Term
How are stomach ulcers caused?
Definition
open sores caused by partial digestion of the stomach lining by the enzyme pepsin and hydrochloric acid in gastric juice.cause is a bacterial infection.
Term
function of large intestine
Definition
water absorption
Term
name two reasons why fibres are important in the diet.
Definition
it is mostly the cellulose in plant material and therefore It aids peristalsis and reduces likelihood of constipation. also, diets high in fiber reduce risk of diabetes, bowel cancer and cardiovascular disease.
Term
highlight the serependipituous discovery of William beaumont's discovery about the digestive systm in the stomach.
Definition
Alexis St. Martin received a gunshot wound to his side. He survived, but wound healed so that the inside of his stomach could be seen from the outside. William Beaumont treated the wound, used the opportunity to study the process of digestion and found that digestive processes within the stomach are physical.
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