1.4 Digestive system anatomy + physiology

Where does digestion begin?

In the mouth

Order of digestive system

mouth, esophagus, stomach, small intestine, large intestine, rectum, anus

Function of digestive system

Break down food fr absorption and distribution of nutrients to the rest of the body.

Smooth muscle function in digestive tract

Involved in mechanical digestion and movement of food through the digestive system

What controls the smooth muscle

Parasympathetic

What absorbs the nutrients in the stomach and small/ large intestine ?

Blood vessels

Mechanical digestion

Any physical breakdown of food such as chewing and grinding food

Function of saliva

Lubricates the food and provides the enzymes amylase and lipase to initiate chemical digestion of starch and lipids

Chemical digestion

Process where enzymes break down food particles into simple chemicals that can be used in the body

Broken down food is packaged into parcels called what

Bolus

Bolus

A term used to describe food after it has been chewed and mixed with saliva

What mechanism controls the contractions of smooth muscle to move the Bolus through the gastric sphincter to the stomach?

Peristalsis

What prevents reflux of food back into the esophagus?

esophageal (cardiac) sphincter

Chyme

Partially digested, semiliquid food mixed with digestive enzymes and acids in the stomach.

What are the three main secretions in the stomach

mucus, hydrochloric acid, pepsinogen

Function of hydrochloric acid

helps break down food and activates the protein pepsin

Pepsin

An enzyme present in gastric juice that begins the hydrolysis of proteins

What is the first part of the small intestine?

duodenum

What occurs in the duodenum?

Chyme is neutralized by bicarbonate from pancreatic secretions

-Receives alkaline bile from gallbladder to neutralize acidic chyme

What does the duodenum create

Large number of brush border enzymes such as protease,lactase, lactase and other disaccharidases and bicarbonate

Function of villi and microvilli in the small intestine

increase the surface area of the intestine, to allow for maximum nutrient absorption

-Absorb water soluble (polar, hydrophilic) digested nutrients into blood, lipids into lactase and chylomicrons and vitamin b12

Where do the blood carrying nutrients go

Pass from small intestine to liver VIA THE HEPATIC PORTAL DUCT

-Allows for liver enzymes to delaminate amino acids

-Convert ammonia to urea

-Metabolize consumed toxins and

- store glucose as glycogen

What does the small intestine absorb

Nutrients and water

What does the large intestine absorb

Left over water and salt from digested food

Where is vitamin k absorbed

large intestine

Hormones involved with digestion

Ghrelin

Leptin

Insulin

Glucagon

Ghrelin

Induces hunger

Leptin

Causes satiety

Insulin

lowers blood glucose levels

Glucagon

A protein hormone secreted by pancreatic endocrine cells that raises blood glucose levels; an antagonistic hormone to insulin.

Enzymes

Proteins that speed up chemical reactions

LIVER FUNCTION IN DIGESTION

Stores and produces bile

Bile function

digest and or lipids