6.1

Serosa

the outermost layer of the small intestine, reinforced by fibrous connective tissue

Muscle Layers of the Small Intestine

Outer layer→ Longitudinal- Peristalsis

Inner layer→ Circular- Segmentation

Submucosa

Layer separating the muscle from the inner lining of the small intestine

Mucosa

Inner layer of the small intestine that absorbs material through its surface epithelium

Features of Villi

\-Microvilli→ ruffling of epithelial membrane

\-Rich blood supply

\-Single layer epithelium

\-Intestinal glands→ release digestive juices

\-Membrane protens→ facilitates transport

Epiglottis

Prevents the bolus from entering the trachea

Uvula

prevents the bolus from entering the nasal cavity

Chyme

The digestion of bolus within the stomach for several hours which turns it into a creamy paste

Peristalsis

when ***longitudinal*** smooth muscle rhythmically contracts and relaxes, causes the food to be moved

Segmentation

\-contraction and relaxation of non-adjacent segments of ***circular*** smooth muscle in the intestines

\-bidirectional

What is the protective layer in the stomach called?

The stomach epithelium contains a **mucous membrane** which prevents the acids from damaging the gastric lining

Bile function

Bile contains bile salts which interact with fat globules and divide them into smaller droplets EMULSIFICATION

Carbohydrate digestion in the small intestine

Enzymes for **disaccharide hydrolysis** are often immobilised on the epithelial lining of the small intestine, **near channel proteins**

Protein digestion in the small intestine

Smaller polypeptide chains enter the small intestine where they are broken down by *endopeptidases* released by the pancreas (neutral pH)

Alimentary canal

consists of organs through which food actually passes through

accessory organs

aid in digestion but do not actually transfer food

Sections of the small intestine

duodenum

jejunum

ileum

Active transport in the small intestine- molecules

glucose, amino acids

Facilitated diffusion in the small intestine- molecules

monosaccharides

Osmosis in the small intestine- molecules

Water

Simple diffusion in the small intestine- molecules

triglycerides

Amylase

\-Breaks amylose into maltose subunits in the mouth and the small intestine (pH\~7)

\-Breaks amylopectin into branched chains called **DEXTRINS**

Breaking down of maltose and dextrin

\-They are digested by the enzymes **maltase** which is fixed to the epithelial lining of the small intestine

\-The hydrolysis of maltose/dextrin results in **glucose monomers**

Breakdown of starch- fuctions of the pancreas

\-releases amylase which is released from exocrine glands

\-produces insulin and glucagon from endocrine glands

Exocrine vs Endocrine

Exocrine glands→secrete their substances onto your body's surfaces

Endocrine glands→ secrete their substances directly into the bloodstream

Key functions of digestion

\-Breaks down insoluble molecules into smaller subunits which can be readily absorbed into body tissues

\-Breaks down inert molecules into usable subunits which can be used by cells and reassembled into new products