Nutrition - Digestion & Absorbtion

what's the main functions of the gastrointestinal (GI) system?

- ingestion, digestion, & absorption of nutrients

- maintaining immune healthy (70%)

- excreting unwanted substances

what organs are in the GI tract?

- mouth

- esophagus

- stomach

- small intestine

- large intestine

- rectum

what accessory organs are related to digestion?

- salivary glands

- gall bladder

- pancreas

what accessory organs are related to metabolism?

liver

functions are controlled by...

- neuromuscular system

- hormones

- chemicals

neuromuscular system

the body's muscles and nerves

voluntary actions of the neuromuscular system

- eating

- chewing

- swallowing

involuntary actions of the neuromuscular system

- motility

- segmentation

what nerves are consisted in the neuromuscular system?

- central

- autonomic

- local

(send & receive signals)

what is hunger?

physiological, blood & energy send signals to the brain

what is appetite?

psychological, controlled by external factors

what is pre-digetion also know as?

cephalic phase

what is pre-digestion?

primes GI tract so it's ready to work

satitation

perception of fullness during a meal - determines duration

satiety

perception of fullness at the end of a meal - determines how long until next meal

ingestion

the process of taking food, drink, or another substance into the body by swallowing or absorbing it.

physical signal to start eating

stomach growling

physical signal to stop eating

sense of fullness

psychological signal to start eating

cravings & sensory appeal

psychological signal to stop eating

perception of normal servings

mechanical digestion

physical breakdown, mixing, and movement of food through the GI tract

chemical digestion

enzymes, acid, and bacteria further breakdown food into absorbable substances

digestion occurs in the...

- mouth

- stomach

- small intestine (upper)

- large intestine (lower)

digestion - mouth

- mechanical chewing

- salivary glands release enzymes

salivary amylase

enzyme released by salivary gland that breaks down carbohydrates

lingual lipase

enzyme released by salivary glands that breaks down fats

there is no enzyme in the mouth that breaks down fats: T or F

True

upper GI tract (esophagus) function

no digestion or absorption of nutrients occurs here, function is to safely move food in the stomach

digestion - stomach

food arrives as a semi-solid and leaves as liquid

stomach acid

hydrochloric acid

stomach enzymes

pepsinogen acid and gastric lipase

hydrochloric acid

denatures protein in the stomach, kills harmful bacteria, and activates enzymes for digestion

pepsinogen acid

activates enzymes to digest protein

gastric lipase

activates enzymes to digest fats

is there an enzymatic digestion in the stomach for carbohydrates? Y or N

No

what is the duration of a meal in the stomach?

2-6 hours

what digests slow in the body?

- fiber

- fat

- protein

what digests fast in the body?

-liquids

-sugar

digestion - small intestine

chemical digestion occurs in the duodenum, jejerium, and ileum

where does majority of digestion occur in the small intestine

duodenum and jejeium

ileum

almost all nutrients digest when fluid reaches here

what two things are indigestible in the small intestine?

carbohydrates and fiber

enzymes produced and released in the small intestine

7: peptidase, enterokinase, lipase, amylase, lactase, sucrose, maltose

digestion - large intestine (lower)

limited digestion occurs here, colon doesn't secrete digestive enzymes

the mouth can absorb nutrients? T or F

False

the esophagus cannot absorb nutrients? T or F

True

what nutrients are absorbed in the stomach?

- water

- alcohol

- caffeine

- medications

what is the main absorption site in the body?

small intestine

mucosal membrane

located in the small intestine

4 ways to absorb nutrients

- passive diffusion

- facilitated diffusion

- active transport

- endocytosis

passive diffusion

nutrients absorbed in a long gradient

facilitated diffusion

nutrients absorbed in a long gradient with a carrier

active transport

nutrients absorbed in both a carrier and energy needed

endocytosis

nutrients engulfed and incorporated

nutrients absorbed in the large intestine

water, sodium, potassium, calcium, magnesium, vitamin K, fatty acids

exocrine pancreas

produces majority of enzymes needed for carbs, protein, and fat digestion

endocrine pancreas

produces hormones needed for regulation of body functions

what hormones are produced by the endocrine pancreas?

insulin, glucagon, gastrin, amylin

gallbladder

stores bile produced by liver and excretes into small intestine

liver

majority of nutrients absorbed go here

key functions of the liver:

- regulates nutrients entering the bloodstream

- produces substances the body needs

- stores excess sugar

- regulates protein breakdown and production

- regulates blood clotting

- clears blood of drugs and toxins

what substances are produced by the liver the body needs ?

cholesterol, bile, immune factors

microflora

found in the large intestine; stimulates immune system, reduces inflammation, decreases diarrhea

structural problems

- acid reflux

- blockage

- inadequate enzyme production/secretion

- missing segments of GI tract

example of an inadequate production of an enzyme in the body

lactose intolerance

gastrophoresis

motility problem; food moving too slow/quick

immune reactions

fighting harmful bacteria

autoimmune reactions

food allergies