Digestive System // Practical 2

Ingestion

taking in foods and liquids into the mouth

Secretion

release of water, acids, buffers and enzymes into the GI tract

Motility

mixing and moving of food and secretions towards the anus

Peristalsis

the process of wavelike muscle contractions of the alimentary tract that moves food along
Occurs in esphoagus

Segmentation

alternating muscle contractions to move contents back and forth, mixing contents
Occurs in the small intestine

Haustral churning

Propels the content of the colon along the large intestine
Occurs in the colon

Digestion

breaking down food molecules into smaller forms for absorption
Occurs in the oral cavity, stomach and small intestine

Absorption

Taking up nutrients into the blood stream for transport to bodily tissues
Occurs in the small intestine

Defecation

the elimination of fecal waste through the anus
Occurs in the larger intestine and anus

Gastrointestinal tract

A series of hollow organs joined in a long, twisting tube from mouth to the anus

Accessory Digestive organs

Secrete substances needed for the chemical digestion of food but through which food does not actually pass as it is digested
Includes - teeth, tongue, salivary gland, pancreas, liver and gallbladder

Bolus

a small round soft mass
Occurs in the mouth

Chyme

a semiliquid mass of partially digested food that passes from the stomach through the pyloric sphincter into the duodenum

Lumen

The inside space of a tubular structure
Surrounded by the mucosa layer

Mucosa

Inner most layer of the stomach lining
Lubricates and protects these organs and cavities

Gastric pits

Secrete hydrochloric acid (HCI)
Located in the stomach

Gastric glands

Responsible for the synthesis and secretion of the gastric juice
Located in the stomach

Chief cells

Synthesis and release of the proenzyme pepsinogen
Found in the stomach

Parietal cells

Responsible for gastric acid secretion
Found in the stomach

Intestinal crypts

Provide stem cells for renewal of the intestinal epithelium
Found in small and large intestines

Circular folds

Large valvular flaps projecting into the lumen of the small intestine

Absorptive cells

Responsible for absorbing nutrients from the intestinal lumen and transporting them across the epithelium to the lamina propria, whence they diffuse into capillaries
Found in small intestine

Goblet cells

Responsible for the production and preservation of a protective mucus layer by synthesizing and secreting mucins
Found in the small and large intestines

Villi

Project into the intestinal cavity, greatly increasing the surface area for food absorption and adding digestive secretions
Found in the small intestine

Microvilli

Increase the surface area in order to absorb more nutrients
Found in the small intestine

peyer's patch

any of several lymph nodes in the walls of the intestines near the junction of the ileum and colon
Vital for immune surveillance

submucosa

A thick layer of loose connective tissue that surrounds the mucosa
Helps with GI secretion

muscularis

Two thin layers of smooth muscles arranged as inner circular and outer longitudinal layer
Helps with GI motility

Mouth (oral cavity)

Point of entry of food into digestive system
Digest of carbohydrates and fats

Lips

Keep food in the mouth during chewing

Hard palate

Prevent food from entering the nasal cavity
Front part of the roof of the mouth

Soft palate

Prevent food from entering the nasal cavity
Back portion of the roof of the mouth

Uvula

Helps prevent food and liquid form going up your nose when you swallow

Tongue

Maneuvers food for chewing and swallowing

Pharynx

funnels food from mouth into esophagus

nasopharynx

cavity forming the upper part of the pharynx

oropharynx

cavity formed by the pharynx at the back of the mouth

laryngopharynx

the lower part of the pharynx

esophagus

Is a muscular tube that transport bolus into the stomach

Upper esophageal sphincter

Prevent air from entering into the esophagus during breathing

Lower esophageal sphincter

Allows food transit from the esophagus into the stomach and prevents the reflux of gastric contents back into the esophagus

Stomach

Food is chemically broken down by acid and enzymes
Digestion - proteins and fats
Absorption - alcohol, aspirin

Cardiac Region

contains cardiac sphincter, which prevents food from traveling back up your esophagus

Fundus Region

Stores gas produced during digestion

Pyloric region

Includes the pyloric sphincter, this ring of tissue controls when and how your stomach contents move to your small intestine

Lesser curvature

gives attachment to the two layers of the hepatogastric ligament

Greater curvature

gives attachment to the gastrolienal ligament

Rugae

Ridges that increase the surface area of the stomach and stretch out to increase stomach volume when the stomach is full

Gastric Juice

digestive secretions of the stomach glands consisting chiefly of hydrochloric acid and mucin and the enzymes pepsin and rennin and lipase

Pyloric sphincter

the sphincter muscle of the pylorus that separates the stomach from the duodenum

Mesentery

Attaches the intestine to the abdominal wall and holds it in place

lesser omentum

a part of the peritoneum attached to the stomach and liver and supporting the hepatic vessels

greater omentum

part of the peritoneum attached to the stomach and to the colon and covering the intestines

small intestine

the longest part of the alimentary canal; where digestion is completed
Digestion - carbohydrate, fats, polypeptides, nucleic acid
Absorption - peptides, glucose, amino acids, fructose, fats, water, minerals, and vitamins

duodenum

to complete the first phase of digestion

jejunum

absorb sugars, amino acids, and fatty acids

ileum

The absorption of vitamin B12 and the reabsorption of conjugated bile salts

brush border enzymes

Line the intestinal walls and form the brush border (a chemical barrier through which food must pass to be absorbed)

ileocecal valve

allow digested food materials to pass from the small intestine into your large intestine

large intestine

to absorb water and salts from the material that has not been digested as food, and get rid of any waste products left over
Digest - None
Absorption - ions, water, minerals, vitamins, and organic materials

cecum

to absorb fluids and salts that remain after completion of intestinal digestion and absorption and to mix its contents with a lubricating substance, mucus

appendix

Involves immune function

ascending colon

absorb the remaining water and other key nutrients from the indigestible material, solidifying it to form stool

transverse colon

Digestion and the excretion of waste products

descending colon

Stores the feces that will eventually be emptied into the rectum

sigmoid colon

To store fecal wastes until they are ready to leave the body

rectum

to receive stool from the colon, let you know that there is stool to be evacuated (pooped out) and to hold the stool until evacuation happens

anal canal

maintenance of fecal continence and defecation

Internal anal sphincter

Keeps the anal canal and orifice closed, aids in the expulsion of the feces

external anal sphincter

Provides voluntary control for defecation

Haustra

Small pouches caused by sacculation which gives the colon its segmented appearance

anus

Stool leaves the body through the anus

Teeth

cutting, mixing, and grinding food

Incisors

Bite into your food

canine (cuspids)

Gripping and tearing

Premolars (Bicuspids)

Crushing and grinding

Molars (tricuspids)

Crushing and grinding

Salivary Glands

Lubricate the mouth and helps with chewing and digestion

Parotid

Produce saliva to keep mouth lubricated

submandibular

lubricates and moisturizes the mouth and throat

sublingual

produces a thick mucinous fluid and lubricates the oral cavity which allows for swallowing, initiating digestion, buffering pH, and dental hygiene

saliva

a clear liquid secreted into the mouth by the salivary glands and mucous glands of the mouth

pancreas

a large elongated exocrine gland located behind the stomach; secretes pancreatic juice and insulin

liver

Produces bile

common hepatic duct

Drain bile from liver

bile duct

Bile to go from the liver and gallbladder into the small intestine

bile

a digestive juice secreted by the liver and stored in the gallbladder; aids in the digestion of fats

gallbladder

a muscular sac attached to the liver that stores bile until it is needed for digestion

cystic duct

Drains the gallbladder into the bile duct

Substrate

the substance that is acted upon by an enzyme

amylase

Secreted by pancreas and salivary gland, break down starches into sugar

lipases

secreted in mouth, stomach and pancreases, break down fats

proteases

Secreted by pancreas, breaks down proteins

pepsin

an enzyme produced in the stomach that splits proteins into peptones

trypsin

an enzyme of pancreatic origin; catalyzes the hydrolysis of proteins to smaller polypeptide units

Diarrhea

Loose, watery stools that occur more frequently than usual

constipation

waste or stool moves too slowly through the digestive tract or cannot be eliminated effetely from rectum

hepatitis

inflammation of the liver caused by a virus or a toxin

pancreatitis

inflammation of the pancreas; usually marked by abdominal pain

appendicitis

inflammation of the vermiform appendix