Lecture 2.5 Flashcards
(26 cards)
What is the primary purpose of food and its digestion?
Energy production (ATP), nutrient supply, thermoregulation, storage of energy, and building blocks for DNA, proteins, and cell membranes.
Food is essential for life, providing energy and nutrients necessary for various bodily functions.
What role do vitamins play in the body?
Cofactors for enzymes
Vitamins assist in biochemical reactions as enzyme cofactors.
What is the role of ions in the body?
Maintain normal ion gradients, biological salts in some proteins
Ions are essential for various physiological processes, including nerve impulse transmission.
What is the temporary energy storage during fasting?
Glycogen, fat stores, protein stores
These stores provide energy when food intake is low.
What is the primary fuel used for 90% of the body’s energy needs?
ATP production
ATP is the main energy currency of the cell.
What are the four processes of the digestive system?
- Digestion
- Absorption
- Motility
- Secretion
These processes work together to break down food and absorb nutrients.
What happens in the mouth during digestion?
Enzymatic and mechanical break-up of food begins
The mouth prepares food for further digestion by increasing its surface area.
What is the role of saliva in digestion?
- Softens and moistens food for swallowing
- Enzymatic breakdown increases food SA
- Defense against bacteria/viruses
Saliva contains enzymes like amylase and lipase that aid in digestion.
What does amylase do?
Breaks down large carbohydrate starch molecules into smaller fragments
Amylase is crucial for carbohydrate digestion.
What is the function of lipase in saliva?
Breaks down triglycerides into free fatty acids
Lipase facilitates the digestion of fats.
What occurs in the stomach during digestion?
- Mechanical break-up of food
- Attack by HCl and pepsin
- Generates small peptides and amino acids
The stomach uses acid and enzymes to further digest food.
Why doesn’t the stomach digest itself?
To prevent extreme pain and damage to the stomach lining
Protective mechanisms are in place to safeguard the stomach.
What is a mucous barrier?
A viscous layer that protects the stomach lining
This barrier is crucial for preventing damage from stomach acid.
What are zymogens?
Inactive enzyme precursors stored in chief cell granules
Zymogens are activated only at low pH to prevent premature digestion.
What happens in the small intestine?
- Neutralisation of acid
- Motility and enzyme attack
- Absorption of nutrients
The small intestine is where most digestion and absorption occurs.
What is the role of bicarbonate in the small intestine?
Helps neutralise acidic chyme from the stomach
This neutralisation is essential for the proper functioning of intestinal enzymes.
What are plicae circulares?
Permanent folds in the small intestine that increase surface area
These structures enhance nutrient absorption.
What are villi?
Tiny, finger-like projections that cover the inner lining of the small intestine
Villi further increase the surface area for absorption.
What are microvilli?
Even smaller hair-like structures on each villus
Microvilli significantly enhance the absorptive surface area.
What is a problem associated with absorption in the small intestine?
Diverticulitis, Coeliac disease, Crohn’s disease
These conditions can affect nutrient absorption and overall digestive health.
What molecules cannot penetrate the phospholipid bilayer?
Polar, charged, and large molecules
The bilayer’s oily nature prevents these substances from crossing easily.
How are monosaccharides absorbed in the small intestine?
Through specific transport proteins in the bloodstream
Monosaccharides are the absorbable units of carbohydrates.
What happens to proteins after digestion?
Absorbed mostly as free amino acids, with some di and tripeptides
Amino acids are essential for various bodily functions.
Where is iron primarily absorbed?
In the small intestine, specifically duodenum and upper jejunum
Iron absorption is critical for preventing anemia.
