Digestion system

Digestion


Mouth

  • Teeth 

    •  help break down food into smaller pieces,( form of mechanical digestion)

  • Saliva - contains an enzyme called amylase

    • Changes are made to molecules of the food, (chemical digestion)

    • Lubricates the food, making it easier to swallow

  • Tongue

    • Moves food to back of the mouth and pushes food into your teeth

Esophagus

  • Beginning contains the epiglottis

  • The epiglottis closes of the trachea when we swallow to ensure food goes down the esophagus, not the windpipe

  • Muscular tube

  • Food, also known as a bolus, is forced down by waves called peristalsis

Stomach

  • Between the esophagus and the stomach is a gate that is closed… sphincter

  • Acid in the stomach acids in more chemical digestion

  • There is a mucus which protects the lining of the stomach

    • Lack of mucus can leave parts of the stomach wall unprotected, leading to ulcers

  • Heartburn:

    • When the sphincter between the esophagus and stomach doesn't close properly and acid splashes up into the oesophagus

    • This burns the lining of the oesophagus and can lead to cancer over time

Mechanical digestion

  • Stomach “churns”

  • 3 layers of muscles that make up the stomach

    • They contract and relax to mix the food with the acid

Chemical digestion

  • Enzyme called pepsin begins to chemically break down protein

  • Food stays in the stomach for 2-4 hrs

  • Leaves the stomach via sphincter between the stomach and small intestine

  • Food leaving the stomach is the consistency of tomato soup and is called chyme

Small intestine

  • 6m long with a diameter of 2.5cm

  • Digestion is mostly completed here

  • Mechanical = muscular contraction to move chyme through

  • Chemical = enzymes from the liver and pancreas help to break down carbohydrates and protein further

  • First 25 cm is called the duodenum, which most enzymes work here. Second, the middle part of the small intestine is the jejunum, which is where most nutrients are absorbed, and the ileum absorbs the remaining nutrients

  • Liver, pancreas, and gallbladder attach to the small intestine by ducts

    • Food doesn't pass through these organs

Small intestine, continued…

  • Usable food/nutrients are absorbed in the small intestine by the villi

  • Villi are small, finger-like projections that make the inside of the small intestine look “furry”

  • food/nutrients enter the villi by diffusion

  • They are significant because they greatly increase surface area of the inside of the intestine

    • More efficient and absorption is higher

Pancreas

  • Secretes pancreatic juice - alkaline (base) which neutralises the stomach acid

    •  - ase = enzyme

    • - sin = enzyme

  • Secretes amylase (digests starch)

  • Produces lipase (break down fat)

  • Produces trypsin (protein processor)

  • Creates and secretes insulin and glucagon

    • Both are important for blood sugar maintenance

  • Insulin lowers blood sugar levels

  • Glucagon increases blood sugar levels

Disorders (pancreas)

  • Pancreatitis: life-threatening inflammation of the pancreas

  • Type one diabetes: immune system attacks the pancreas

  • Type two diabetes: doesn’t produce enough insulin

  • Pancreatic cancer: difficult to treat cancer (5 year survival rate of less than 5% of people)

Liver

  • Produces bile, which is stored in the gallbladder and is involved in mechanical digestion

  • Breaks up fat droplets into smaller droplets

  • If cholesterol is high in the body, bile becomes concentrated, causing gallstones

    • Some individuals have their gallbladder removed and hae to be careful of their diet

Large intestine

  • 1.5 m long with a diameter of 6.5cm

  • Also known as the colon

  • 3 parts: ascending, transversal, and descending colon

  • Absorption of water

    • Too much water absorption because waste is traveling too slowly is constipation - more fibre, like fruits and veggies

    • Too little water absorption, because waste is traveling too quickly is diarrhea - most likely caused by a foreign body (bacteria or virus)

      • Diarrhea is the body’s way of getting rid of it fast

      • Some probiotic yoghurt can help balance the good bacteria in your gut

Large intestine continued…

  •  The large intestine is also involved in vitamin synthesis

  • Anaerobic bacteria (don't need oxygen) in the large intestine synthesize some B vitamins along with vitamin K

  • The normal bacteria we have in our gut is beneficial ias it kills harmful bacteria that may enter, and try to colonize out intestinal tract

  • Waste stays in the large intestine for 18-24hrs

  • Feces are stored in the rectum until it is full and are then expelled through the sphincter (anus)

    • Feces is brown from the dead blood cell that are being expelled from the body

  • The entire journey from mouth to anus can ast form between 24-36 hrs

Appendix

  • Not used for anything

  • Normally found at the bottom right side of the body as a tube-like extension of the large intestine

  • Also called the cecum

  • If it gets infected, it is removed. If not removed, it can burst, spreading infection throughout the abdominal cavity


Vitamin Chart:


vitamin

Major role in the body

Mineral

Major role in the Body

A

Ensures healthy skin and eyes

Ca

Strong bones and teeth

Muscles - control over contraction

D

Keep bones and immune system strong and teeth

P

Strong bones and teeth

E

Ensures that the cell membrane, specifically blood cell strength

Fe

Helps the body produce haemoglobin







Diagrams:


Villi:








Digestion system:


Gerd

  • Symptoms:

    • Burning in the chest

    • Backwash

    • Trouble swallowing

    • Coughing

    • Inflamed vocal cords

  • Cause: 

    • Obesity, pregnancy, smoking, delayed stomach emptying, eating large meals, eating at night, having caffeine, drinking alcohol

  • Diagnosis:

    • Upper GL, Upper endoscopy, etc