Digestion, Absorption, and Transportation

Brains role in Hunger (hypothalamus) 

Responsible for getting us to seek food and results from nerve cells and hormones. 

Two Systems Coordinate Digestive Process

1) Endocrine System (ex; hormones)

2) Nervous System

Body Processes Include (in digestion)

1) Coordinating Tasks of mouth

2) Diaphragm Assistance 

3) Movement in Digestive Tract 

4) Fluid Regulation 

5) Digestive Enzyme Activation 

6) Protection from Digestive Juices 

7) Periodic Waste Excretion 

Hormones (examples + Reponses) 

Gastrin - Hydrochloric acid is secreted into the stomach 

Secretin - Bicarbonate-rich juices are secreted into the small intestine. 

Cholecystokinin - Bile is secreted into the duodenum, AND  bicarbonate-rich juices are secreted into the small intestine.  

GI Track

Long, flexible muscular tube (mouth to anus)

Inner surface is called lumen

Bolus

Food mixed with saliva and beverages (goes down pharynx into the the stomach) 

Chyme 

Bolus mixed with gastric juices

Parts of the small intestine

Duodenum, jejunum, ileum (at of the large intestine is the ileocecal sphincter) 

Sphincters in Digestive System

Upper Esophageal Sphincter - Top of esophagus. Opens in response to swallowing. 

Lower Esophageal Sphincter - Bottom of the esophagus. Prevents the reflex of stomach contents.

Ileocecal Sphincter - Ends of intestine. Allows emptying into the large intestine.

Pyloric Sphincter - Bottom of the stomach. Holds chyme in the stomach and prevents intestinal contents from backing up into the stomach.

Organs/Glands of digestion + Action

Salivary Glands - Fluid helps in swallowing.

Gastric Glands - Fluids mixes with bolus. They are then broken down by acid. 

Pancreas - helps in digestive break down 

Liver - Bile is stored

Gallbladder - Bile emulsifies fat so that is can be broken down further. 

Intestinal (crypt) glands - Helps digest carbs, fat, protein and mucus protects intestinal wall. 

Emulsification

Break down of fat. Hug fat like bumble bee and slowly take them apart.

Undigested Residues

• Continue through the GI track. 

• Exercise the GI muscles 

• Retain Water 

Large Intestine 

Fibre is Fermentation by Bacteria 

Types of Absorption 

• Simple Diffusion - High to low [] and simple movement. 

• Facilitated Diffusion - Requires a specific carrier that transports a nutrient 

• Active Transport - Uses a carrier protein and transports from low to high []. 

Villi

Recognize/Selects nutrients body needs

Microvilli

Contains hundreds of enzymes and pumps, can recognize nutrients.

Crypt Glands

Secret intestinal juices. Goblet cells make mucus.

Blood does what 

• Delivers oxygen and nutrients to tissue

• Removes CO2 and waste from tissues

Blood (From GI track travel)

Blood leaving the digestive tract does so via the hepatic vein, which leads to the liver. The hepatic vein breaks out into capillaries and back to heart. 

The Lymphatic System

• One way route

• Circulates between cells in tiny vessels. 

• Collected in the thoracic duct and enters the bloodstream via the left subclavian vein.

Gastrointestinal bacteria (flora)

• Prebiotics - Supports growth/activity of bacteria colonies in GI tract. 

• Probiotics - Microorganism change conditions/native colonies in GI tract. 

• Symbiotic - Provide prebiotics and probiotics 

• Ferment fibre - Provides energy from bacteria.

Common Risk of Choking

• Children, Alzheimer’s, Parkinson’s, Pneumonia 

• Chunks of food 

• Hot Dog

• Nuts 

• Whole Grapes 

• Popcorn 

• Raw Carrots 

• Marshmallows 

• Gum 

• Peanut Butter

Belching

Occurs from swallowing air

Flatulence

Is normal, many expel a lot of gas several times a day.

Heart Burn caused by  

• Eating Certain Foods

• Wearing tight clothes

• Lying down when eating

• Some meds 

• Smoking 

• Weight gain 

• Possible defected sphincter 

Ulcer Causes

• Bacteria infection (helicobacter pylori) 

• NSAIDS (non steroidal ant-inflammatory drugs) 

• Disorders producing extra gastric acid