Lecture 21 Flashcards
What must be done to the complex forms of food before it can be used?
the complex forms of food are turned into the individual building blocks (carbohydrates to mono saccharides, proteins to amino acids, nucleic acids to nucleotides and fat into free fatty acids, MAG and cholesterol), the process of breaking these bonds can be used to produce ATP.
What do salivary glands secrete?
Salivary glands secrete saliva (neutral pH) which contains mucous and amylase (which starts the digestion of carbohydrates).
What does the stomach do and secrete? What cells are found in the glands?
The stomach does storage and mixing of food with gastric juices, it secretes acid (about 0.1 M of HCl) for denaturing, pepsinogen for protein digestion and a mucous layer to protect it.
The stomach does storage and mixing of food with gastric juices, it secretes acid (about 0.1 M of HCl) for denaturing, pepsinogen for protein digestion and a mucous layer to protect it. It contains chief cells which secrete enzymes (pepsinogen) and parietal cells which secrete protons and Cl- to produce HCl.
What do the pancreas, liver and small intestine do?
The pancreas is slightly alkaline and it secretes most digestive enzymes (amylase, lipase and many proteases). The liver synthesises bile salts/acids which are stored in the gall bladder which are important for fat digestion. The small intestine is the final phase of digestion and absorption.
What are the main phases of digestion?
Digestion has two main phases: the hydrolysis of bonds connecting monomer units in food macromolecules (glysodic bonds for carbohydrates, peptides for proteins and ester bonds for fatty acids) and 2. the absorption of products from the gut into the body.
What are some common sugars?
glucose (5 carbon ring ended in oxygen 6 atom ring), fructose (4 carbon ring ending in oxygen, 5 atom ring). Sucrose is a combined form of fructose and glucose.
What are common enzymes which act on carbohydrates?
amylase acts on starch, maltase acts on maltose (into 2 glucose), lactase acts on lactose (into galactose and glucose), sucrase acts on sucrose (into fructose and glucose), isomaltase acts on isomaltose (into 2 glucose).
How is lactose intolerance caused?
Lactose intolerance is caused by a deficiency of the lactase enzyme, this causes bloating, flatulence and diarrhoea as intestinal bacteria ferment it.
How does absorption occur in the small intestine and then what happens?
The small intestine has specialised structures to create a vast surface area for absorption, these are the villi and microvillia (brush border). Sugars are water soluble and cannot easily diffuse across cell membranes and hence there are active and facilitator transport proteins. The two types are SGLT1 (sodium into the cell with concentration gradient to pull glucose in) and GLUT 2 (glucose pulled out by concentration gradient on the opposite side) for the intestines. Once in circulation it is taken up by other tissues via transporters (GLUT 4 for muscle and adipose, GLUT 1 for brain).
What is Coeliac disease?
Coeliac disease is when the body reacts against gluten, this causes antibodies to react and flatten the villi, this makes it less able to absorb nutrients.
