Digestive system Flashcards
Whats the role of the digestive system?
Break down food for energy, 4 major processes.
Ingestion: food enters through mouth
Digestion: Breakdown food into smaller components (Mechanical & Chemical)
Absorption: Nutrients are absorbed into bloodstream so it can be delivered to all cells in body
Egestion: Removal of waste production
What are the types of digestion
Mechanical and Chemical
Mechanical digestion
Physical breakdown of chunks of food into smaller pieces. Happens mainly mouth and stomach.
Chemical digestion
Chemical breakdown of large complex food molecules into smaller simple nutrient molecules that can be absorbed by the blood. Begins in mouth and stomach occurs in SI
Whats an enzyme?
Proteins which act as biological catalyst. Regulate/increase the rate of chemical reactions (like metabolism) within the body.
Basically makes reactions faster
Why can enzymes be used over and over again?
Enzymes do not get used up or altered permanently so they can be used again and again
What does enzymes do to activation energy?
Decrease activation energy of a reaction, this is energy needed to start a reaction
what is a substrate?
molecule that is getting broken down or built up.
Whats an active site
Enzymes have active sites, an area on an enzyme which has a special shape so that only a specific substrate will fit.
every substrate needs its own enzyme in the body
How do enzymes work?
- Subtrate and enzyme need to be in same area of body
- Subsrate fits into active site of enzyme (if same shape)
- Catalysis occurs (substrate broken down/built up)
- Products released from active site
- Enzyme grabs new substrate and repeats process
What is organic compounds
Need to be broken down before being absorbed into bloodstream. Eg Carbohydrate, protein, fat
What is Inorganic compounds?
Can be absorbed directly into bloodstream. Eg Vitamins, minerals, water
Whats a protein, why do we need it?
Composed of long chain of aminoacids, found in meat, fish, legume.
they are the building blocks for muscle
Whats a carbohydrate, why do we need it?
Composed of hydrogen, carbon, oxygen in fixed ratio. Can be simple/complex. Found in sugars, starches, bread, fruit, monosaccarides.
Main source of energy
Whats a fat/lipid why do we need it?
Can be saturated (animals/fats/butter) Unsaturated (oils)
Main component of cell membranes and long term energy storage, insulates and protects
How is glucose made? (carbohydrate)
starts from polysaccharide starch glycogen, enzyme amylase breaks it down into maltose (disacc), maltase breaks it down into Glucose (monosacc)
How is glucose + fructose made? (carbohydrate)
Starts from sucrose (disacc), enzyme sucrose breaks it down into glucose + fructose (monosacc)
How is glucose + galactose made? (carbohydrate)
Starts from lactose (disacc), enzyme lactase breaks it down into glucose + galactose (monosacc)
Whats the 3 levels of a protein?
Polypeptide: A long sequence of amino acids
Dipeptide: 2 amino acids
Amino acid: one protein unit, 20 in total humans need.
Lipids?
triglycerides is made of one glycerol backbone and 3 fatty acid chains
bile is an emulsifier and lipase breaks down lipids
eg fatty acids can be saturated (no doulbe bond) or unsaturated (double bond)
Teeth?
Tear and grind food into smaller pieces
Tongue
Mixes food, pushes to back of mouth
Epiglottis
Covers trachea when swallowing to prevent food from entering lungs
Saliva
moistens food and contains salivary amylase which begins carbohydrate digestion
Which parts of the mouth are mechanical and chemical digestion?
Tongue, teeth - mechanical
Saliva (amylase enzyme, prod by salivary glands) - chemical
What type of digestion happens with each nutrient in the mouth?
Carbohydrate: Chemical (complex polysaccharides are broken down by amylase to disaccarchies) Mechanical breakdown
Lipids: Mechanical breakdown
Lipids: mechanical breakdown
Whats bolus
Food mixed w saliva
Esophagus structure and func?
Structure: Long muscular tube that connects the mouth to the stomach
function: Smooth muscles of walls of esophagus produces arhythmic wave of contractions that push food down into stomach. Called peristalsis.
What is muscles of esophagus contracting called?
Peristalsis, function of esophagus
If u ate upside down would food still go down stomach?
Yes because the muscles contracting is what causes food to go down not gravity
How does epiglottis help safety
stops food from going down larynx
what are 2 involuntary muscles
smooth muscles, heart
Stomach structure and function?
Expandable bag, rugae (folds) allow it to expand after eating. Sphincters that regulate food entering and leaving. (esophageal, pyloric) Ph of 2, produces mucus to protect from acidic environment
Func: 1.Chemical digestion, secretes gastric juices (HCL, mucus (protection), pepsinogen (pepsin, breaks down proteins to dipeptides))
- Mechanical digestion (churning to mix food)
What are the 2 sphincters in the stomach?
Esophageal sphincter (controls food entering)
Pyloric sphincter (controls food leaving)
What is Pepsin?
Enzyme responsible for breaking down proteins in the stomach
What would happen if cells lining stomach created pepsin? Alternative?
If cells lining the stomach created pepsin, the pepsin would break down the cell membrane bc its made of proteins.
Instead, cells lining in stomach creates a precursor known as pepsinogen which is an inactive form of pepsin. Once pepsinogen is secreted into stomach it interacts w HCL (low ph) and converts to active form pepsin
what type of digestion is happening in the stomach?
Carbohydrates: Mechanically (churning)
Lipids: Mechanically
Proteins: Mechanically churn, chemically (due to pepsin)
Small intestine structure and function?
Structure: 3 main section: Duodenum, jejunum, ileum
Func: Primary site of absorption, breakdown of macromolecules thro chemical digestion
food now called chyme once enters SI
Duodenum structure and func?
structure: first shortest portion of SI, 10 inches long in adults
Func: Primary site of chem digestion,
cells release enzymes,
pancreas releases hormones, enzymes and sodium bicarbonate,
gallbladder releases bile (prod in liver) breaks down lipids
Sodium bicarbonate helps neutralize stomach acid as when food leaves stomach its acidic, can destroy lining of SI
Pancreas?
Secretes pancreatic juices, enzymes break down carbohydrates, protein and fat (amylase, lipase, fat), sodium bicarbonate, hormones (glucagon, insulin)
Liver?
produces bile that helps emulsify fats
Gallblader?
Stores and concentrates bile, bile duct releases bile into duodenum
Intestinal juices?
Made in duodenum,
maltase, sucrase, lactase for carbo
peptidase for protein
lipase for fat digestion
What type of digestion is happening with each type of nutrient in duodenum?
carbo - amylase (pancreas), lactose (duodenum), maltase (duodenum) all chemical
Lipids - lipase (pancreas) chemical
Proteins - trypsin (pancreas), peptidase (dudenum) chemically
What happends when u have high blood sugar and low blood sugar
high (after meal)
Insulin is released by pancreas
1. stimulates glucose uptake by cells
2. glucose turns into glycogen formation in liver
low (fasting)
glycogen released by pancreas
1. stimulates breakdown of glycogen to glucose in liver to be released into bloodstream
Jejunum and ileum structure and func?
Structure: jejunum (8ft), ileum (12ft), finger like projections called villi (have microvilli)
Func: main func is chemical digestion and absorption of nutrients, villi have capillary bed so nutrients can be absorbed into bloodstream and transported around body
whats the benefit of having both villi and microvilli?
increased surface area for absorption
How does food travel forward thro SI
parastalysis
Large intestine struc and func?
Struc: approx 5 feet long, 3 main sections: ascending, transverse, descending
func: main site of water and vitamin absorption
too much water - dirrehea
not enough - dry/constipation
fiber = cellulose
