What is our body made up of?
[Hint: cells –> Organ systems]
Cells –> Tissues –> Organs –> Organ systems
Another term for digestive system
Alimentary canal
Describe the process of absorption
- Large insoluble molecules broken down into small soluble ones through the process of digestion
- Small soluble molecules pass through the wall of the small intestine into the blood
Examples of large and small soluble molecules
Large:
- Carbs
- Proteins
- Starch
Small:
- glucose
What are carbohydrates made up of and what is its simplest units
- Carbon
- Hydrogen
- Oxygen
> Monosaccarides [1 unit] (e.g. glucose)
What are proteins made up of and what is its simplest units
- Carbon
- Hydrogen
- Oxygen
- Nitrogen
> Can be digested into amino acids
What are fats made up of and what is its simplest units
- Carbon
- Hydrogen
- Oxygen
> Glycerol + fatty acids
What are enzymes made up of and what is their function
- Made of proteins
> Produced by digestive system to help speed up the rate of chemical digestion of food molecules into small, soluble subunits
Differences between chemical and mechanical digestion
Mechanical:
- Physical breaking up of food into smaller pieces
- No new substances are formed
Chemical:
- Chemically breaking down large molecules into smaller soluble ones by enzymes
- New substances are formed
Function of mouth + saliva
- Ingests food
- Mechanical digestion of food into smaller pieces through chewing
- Begins chemical digestion of starch into glucose
- Saliva moistens/ lubricates food
Function of esophagus
Transports food to stomach
Function of liver
- Produces bile that is secreted into the small intestine
- Is needed to speed up emulsification of fats
[Note: It’s physical digestion]
Function of stomach
- Mechanical digestion by churning up food
- Hydrochloric acid lowers pH level and Kills bacteria/ micro-organisms
- Enzymes chemically digests the proteins
Function of Gall bladder and bile (green)
- Stores bile
> Bile ONLY speeds up digestion :)
Function of pancreas
- Secretes pancreatic juice, which contains (all) enzymes into the small intestine
- To neutralise the acidic chyme from the stomach as it is an alkali
- These enzymes speed up chemical digestion of carbohydrates proteins and fats into small, soluble subunits
Describe the process of emulsification
- Large fat droplets are emulsifies to small fat droplets
- This increases the surface area of fat molecules for enzymes to act on
Function of the small intestine
- Large, insoluble nutrients broken down
- small, water-soluble molecules
- Absorbed through the wall of the small intestine into the blood stream
What is assimilation
The movement of digested food from blood to other body cells
How is the small intestine adapted for its function
- Inner walls of small intestine is highly folded and had finger-lie projections called villi
- Villi increase surface area, thus increasing the rate of diffusion to volume ratio and hence the rate of absorption of nutrients
- Rich network of capillaries which absorbs the nutrients quickly, maintaining a steep concentration gradient for rapid diffusion
Function of the large intestine
- Undigested food (e.g. Remaining water, vitamins and minerals) are absorbed
Effect of reduced absorption of large intestine
Water:
- Dehydration
- Watery stools
Vitamins:
- Less vitamin C –> suffer rom scurvy
- Less vitamin D –> less calcium absorbed, rickets
Minerals
- Less iron absorbed –> less red blood cells made
2 possible effects of small intestine have a decreased surface area
- Less assimilation/ diffusion
2. Slower rate/ less absorption of digested food
