digestive system

digestive system functions

• mechanical and chemical breakdown of food

• absorption of nutrients

alimentary canal

tube that food passes through and several accessory organs

FUNCTION of the digestive system: mouth

• breaks down starch

• chewing and moving food

• salivary glands produce amylase and mucus

three salivary glands

3 pairs: parotoid, submandibular, sublingual

PARTS OF THE DIGESTIVE SYSTEM: esophagus

smooth muscle tube; muscles contract to move food into stomach

FUNCTION of the digestive system: Stomach

• breaks down proteins

• mechanical and chemical digestion

• end result is chyme

mechanical digestion

muscle contraction breaks down food

chemical digestion

stimulated by histamine and gastrin

FUNCTION of the digestive system: small intestine

• absorption of all nutrients, villi increase surface area

FUNCTION of the digestive system: pancreas

• secretes pancreatic juice that increases the PH of chyme

• secretes hormones insulin and glycogen to regulate blood sugar

FUNCTION of the digestive system: liver

• release glycogen to regulate blood glucose levels

• produces bile

• protein metabolism

• stores vitamins

bile

breakdown of lipids and fats

gallbladder function

stores and concentrates bile

FUNCTION of the digestive system: large intestine

• absorbs water, secretes mucus, contains bacteria

1) cecum: start of large intestine, appendix and illium

2) colon: mass movements (peristalsis)

3) rectum: stores waste

4) anus: muscular sphincter controls waste exit

NUTRIENT ABSORBTION: mouth

• tastes good= more saliva produced

• tastes bad= less saliva produced

NUTRIENT ABSORBTION: stomach

gastric pit

pathway of food through stomach

pepsinogen and HCL make pepsin which breaks down proteins in food

what is in the gastric pit

mucus cells, parietal cells, chief cells

NUTRIENT ABSORPTION: liver and pancreas

• liver always producing bile

• duodenum produces hormone CCK in response to food consumption

• CCK causes gallbladder to contract and release bile

• CCK causes pancreas to make digestive enzymes

NUTRIENT ABSORPTION: small intestine

• lacteal= lymphatic vessel

• chylomicrons= protein that surrounds emulsified fats

• carbs and amino acids are absorbed by capillaries in the hepatic portal vein system

what is an emulsified fat

the process of breaking down fat into smaller blood cells so that food can be digested more easily

NUTRIENT ABSORPTION: large intestine

• peristalsis= moves food toward the rectum

• fiber stops intestine from digesting itself

FUNCTION of the digestive system: kidneys

regulating water balance, salt concentrations, PH levels, blood pressure

glomerular filtration rate (GFR)

how much blood passes through the glomeruli every minute

ADH function

causes more aquaporins to open which causes increased water retention

Aldosterone

increases sodium reabsorption in distal convoluted tubule

goblet cells

produce mucus

chief cells

make gastric lipase and pepsinogen

parietal cells

make HCL

how are lipids broken down

bile

how are proteins broken down

pepsin and pancreatic juices that contain enzymes

how are carbohydrates broken down

amylase

how are nucleic acids broken down

pancreatic juices

which cell types can convert one fuel molecule to another and send other fuel to other molecules

fat and liver cells

which cell type prefers to burn fatty acids as fuel

liver