A&P II--Digestive System

Food actually passes through the GI tract, whereas accessory organs only assist in digestion by enzyme, fluid secretion, etc.

Liver, gallbladder, pancreas, teeth, tongue salivary glands, etc.

Oral cavity, pharynx, esophagus, stomach, small intestine (duodenum, jejunum, ileum), Large intestine (Cecum, ascending colon, transverse colon, descending colon, sigmoid colon), rectum, anus.

Ingestion (mastication), Deglutition (swallowing), Digestion (mechanical/chemical), Absorption, Defecation

Eating/ Chewing (teeth, tongue, masseter muscle--innervated by trigeminal nerve)

Swallowing-- Vagus (X) and Glossopharyngeal (IX) nerves.

Mechanical (through movement--chewing/grinding)

Chemical (Enzymes, hormones--breaks down by hydrolysis)

1. Proteins
2. Reaction specific
3.Can be used repeatedly (for one reaction)
4.PH and Temp sensitive

The breakdown of molecules using water.

Small intestine (Jejunum)

Ejects materials from digestive tract (Reflex)

Serous membrane that lines the abdominal cavity.

Membrane made up of areolar/adipose connective tissue and mesothelium. Secretes watery fluid to reduce friction.

Located on outside attached to muscle wall/ Located directly on organs in abdominal cavity.

Organs covered on all sides by visceral peritoneum vs. organs located behind peritoneal cavity covered only on one side by parietal peritoneum.

Pancreas, duodenum, kidneys, ascending/descending colon.

Liver, gallbladder, stomach, small intestine, Transverse colon, spleen etc.

Greater and lesser omentum, falciform ligament, mesocolon, mesentery proper.

inferior, between body wall and anterior surface of small intestine/
On ventral side of stomach, between stomach and liver.

Fold of peritoneum between liver and anterior abdominal wall.

Mesentery on portion of large intestine.

Thick mesenterial sheet, covers all of small intestines with exception of first ten inches.

Mucosa, submucosa, Muscularis externa, and serosa or adventitia.

Epithelium (can be simple or stratified squamous, depending on location)

Lamina propria (layer of areolar tissue w/ blood vessels, sensory nerve endings, smooth muscle cells, and scattered lymphoid tissue)

Muscularis mucosa (several thin layers, smooth muscle)

Nerve plexus that regulates glands and muscularis mucosa (meissner plexus)

Inner circular layer of muscle and outer longitudinal layer of muscle.

Connective tissue (Serosa if inside peritoneal cavity, adventitia if outside)

Endocrine and nervous systems.

Controls hormones secreted into blood to act on specific target organ.

Enteric nervous system and autonomic nervous system.

Nervous system in GI tract helps control motility and secretion.

Nerves connect with ENS to influence motility and secretion of GI organs.

Increases/Decreases.

Vagus (X)

Lips of oral cavity/ Membranous fold of tissue attaches to center of upper lip and between two front teeth.

Gums--mucosal tissue over mandible and maxillae bones in mouth.

Palatine and Maxillae

As a form of protection for tissue if put under some sort of stress, i.e avid flossing, etc.

Helps to close off nasopharynx during swallowing of food, posterior portion supports uvula.

Manipulates materials inside mouth, mechanical processing (compression/abrasion), sensory analysis by touch, temp, taste receptors, secretion of mucins and lingual lipase.

Hypoglossal (XII)

Connects body of tongue to mucosa.

Soft rounded ball of digestive contents.

Assists tongue in moving materials.

Part of lymphatic system and helps protect against infection, traps germs coming through mouth and nose.

Parotid glands, reaches back of molars of mouth from gland, watery saliva here prevents blockage in ducts.

Parotid, sublingual, and submandibular glands.

Inferior to zygomatic arch, deep to skin covering lateral/posterior surface mandible.

Either side of lingual frenulum, posterior to teeth.

In floor of mouth within mandibular groove.

Mucins and enzymes.

Watery (Serous acini), Thick/Mucous (Mucus Acini), Normal/In-between consistency (both serous and mucus acini)

Lubricating mouth and materials inside mouth

Provide sensory info about food

Dissolving chemicals that stimulate taste buds

Begins digestion of carbs.

Water, electrolytes, Enzymes, antibodies.

Made in salivary glands, and begins working in mouth to start breakdown of carbohydrates before swallowed.

Mixes with H2O and starch, and bonds in carbs are broken down.

Increase secretion.

ANS (Parasympathetic)--nerves VII (Facial), IX (glossopharyngeal), and X (Vagus).

Alveolar processes of mandible and maxillae.

Incisors, Molars, and canines.

Useful for tearing and slashing (has single root)

Adapted for crushing and grinding (3+ roots)

Useful for clipping and cutting (One root only).

Temporary/primary teeth (found in children)--about 20.

Nasopharynx, Oropharynx, and Laryngopharynx.

Oro and laryngopharynx (Stratified Squamous epithelium).

Superior portion has skeletal muscle to start deglutition process and move bolus into esophagus.

12 inches long, located posterior to trachea, and anterior to vertebral column.

Remained closed until swallowing, and open to allow food into esophagus and stomach, respectively. Prevent backflow of food into nasopharynx and stomach acids back into lower esophagus.

Esophageal hiatus.

Posterior.

Structure called epiglottis closes when food is swallowed to block off larynx and allow food to slide over, going down esophagus only.

Buccal (bolus created)
Pharyngeal (Epiglottis closes over larynx, soft palate and uvula block off nasopharynx)
Esophageal phase (Peristalsis occurs)

Initial swallowing voluntary, but proceeds automatically once started and peristalsis takes over.

Helps to close off opening to nasopharynx, preventing food from entering nasal cavity.

Swallowing center of medulla oblongata (cranial nerves IX and X)

Contraction of circular and longitudinal smooth muscle layers of muscularis externa, move food through digestive tract.

Superior 1/3 is skeletal, rest is smooth.

IX and X

Reflux of stomach acids in lower end of esophagus causes burning sensation in middle of chest.

Protrusion of part of stomach upward into chest through opening in diaphragm.

Abonormal opening in diaphragm allowing abdominal contents to move into chest cavity (birth defect).

Simple columnar epithelium

Lubrication in stomach, protect against acidity.

Glands in stomach that secrete gastric juice and mucus/ invaginations of epithelium in stomach.

Hydrochloric acid and Intrinsic factor.

Kills bacteria, activates pepsinogen, denatures proteins.

Needed for B12 production (blood cell formation, nervous function)

Pepsinogen

Digests proteins (activated by HCl, secreted inactively so to not digest organs containing it).

Gastrin

Hormone that controls stomach function.

Secreted into blood stream (hormones)

Loose connective tissue

Folds of mucosa that allow gastric lumen to expand.

Has three layers: Inner oblique layer, circular layer, and longitudinal layer.

For churning of stomach contents (chyme)

Longitudinal

Serosa--mesothelium and areolar.

Water and Carbon dioxide combine to make a bicarbonate and hydrogen ion which is then pumped into lumen.

Membrane of parietal cell of stomach.

1.5-3.5

Kills ingested bacteria, acidic environment for protein digestion, and activates pepsinogen into pepsin.

Mechanical

Inactive form of enzyme

Chief cells

Parietal secretes HCl, Chief secretes pepsinogen (and HCl later activates the pepsinogen to pepsin).

Enzyme that digests proteins in duodenum.

Milky white substance of food mixed with gastric juice.

Acidic

Cephalic, Gastric, and Intestinal.

Impulses from sensory (thinking about, smelling, and seeing food) go to hypothalamus, and it initiates gastric juice secretion (Vagus nerve)

Gastric phase begins when food enters stomach--gastrin stimulates HCl, stomach becomes acidic. Neural stimulation increases secretion of gastrin, and ANS helps stimulate motility/secretion.

Intestinal phase begins when food reaches duodenum. CCK and secretin stomach churning.

In duodenum. (Liver, Gallbladder, Pancreas).

Stops stomach churning, increases pancreatic digestive enzymes, controls gallbladder secretions, and acts on hypothalamus (feeling of fullness).

Shuts down stomach, acts on pancreas (increases bicarbonate).

Inhibition of gastric motility/secretion when stimulated by presence of low PH acid levels in duodenum.

2-3 hours

Expulsion of stomach and proximal small intestine contents =, resulting in glottis closing off, larynx raising, and soft palate closing off nasopharynx, diaphragm contracts, and esophagus and esophageal sphincter open to allow contents to come back up--controlled in reticular formation of medulla oblongata.

Remaining carb and protein digestion by enzymes.

Absorption (water, nutrients) occurs--90% (jejunum)

About 8 liters.

Pyloric sphincter/ ileocecal valve.

Intraperotineal

About 19.7 Ft. in length.

Increases surface area.

Folds of mucosa and submucosa in small intestine (can be seen without microscope)

Simple columnar epithelium

Yes, for mucous secretion on intestinal surface for easy movement and protection from acidic chyme.

Lacteal--Lymph vessel that absorbs fat.

Layer of disaccridases (Maltase, sucrase, and lactase) that help break molecules down further to monosaccharides to be absorbed.

Intestinal glands located deep between villi

Eneteroendocrine cells (hormones CCK and Secretin)

Lysozyme (antibacterial functions)

Submucosa--Make mucus for acid neutralization.

Located in ileum, consist of cells that prevent invasion of bacteria in digestive tract.

Immune cells, found throughout GI tract

Circular and longitudinal layers--smooth muscle, except in upper 1/3 of esophagus. Constriction and segmentation are possible.

The duodenum because it is retroperitnoeal.

Constriction of circular muscle fibers in small intestine.

Automatically, longitudinal and circular muscle layers together produce peristaltic movement.

Produces bile and detoxifies substances.

Stores and concentrates bile produces by liver.

Produces enzymes to breakdown fats, proteins, and carbohydrates.

Divides right and left lobes of liver.

Right and left, Quadrate, and Caudate lobes.

Intraperitoneal.

Oxygenated--from aorta via hepatic artery

Deoxygenated w/ absorbed foods--from small intestine via hepatic portal vein.

Oxygen

Contain blood entering liver that comes from branches of hepatic portal vein and hepatic artery.

Detoxifies them.

Bile that is leaving the liver

Stored in liver for later use (stores glucose as glycogen)

Cannot be stored so regulated/detoxified.

Production of bile.

Emulsifies fats--made in liver and stored in gall bladder.

Water and bile salts

Bile pigment (responsible for making feces brown--breakdown of red blood cells, hemoglobin)

Cholesterol

Insoluble minerals and salts that deposit and form when bile becomes too concentrated.

Digestion of lipids and helps dilute and buffer acids in chyme entering small intestine.

Cystic duct.

Right/left hepatic duct, common hepatic duct, cystic duct to gallbladder, common bile duct joins with pancreatic duct to form ampulla of vater.

Structure where pancreatic duct and common bile duct merge.

Smooth muscle ring at opening of ampulla (controls secretions into duodenum)

In fossa, posterior surface of liver's right lobe--intraperitoneal

Mucosa (simple columnar), no submucosa, Muscularis, and serosa.

To allow it to expand

Contracts (gallbladder) and empties contents into duodenum

Gallstone will begin to form.

CCk causes relaxation of sphincter of oddi, allowing bile release.

From bile sitting in gallbladder, cholesterol can crystallize, forming the stones.

Yes, but eating certain foods may cause discomfort, irregularities in digestive process because there is now no place for bile to be stored or concentrated, so bile just constantly drips from liver into small intestine.

Deep to stomach--retroperitoneal.

Parts of pancreas--within loop formed by duodenum.

To make pancreatic enzymes

Insulin and Glucagon.

99% exocrine.

The pancreas.

Carbohydrates.

Proteins

Activated by enterokinase in duodenum.

Trypsin then activates Chymotrypsinogen and procarboxypeptidase into chymotrypsin and carboxypaptidase.

Fats

RNA and DNA.

In duodenum.

Hydrolysis.

Helps raise PH of acidic chyme.

Secretin.

Enzymes/Bicarbonate.

(Vagus nerve) causes pancreas to secrete more enzymes.

Build up of bilirubin (byproduct of RBCs) causing yellow pigment of skin, eyes, etc.

Tumor blocking biles ducts

Too many RBCs dying, going to liver, liver damage, etc.

Inflammation of pancreas.

Monosaccharides, monoglycerides/fatty acids, and amino acids.

SGLUT

Hepatic portal/Liver

Pump would be needed to move extra Na+ back out of the cell on other side.

Lipoproteins consisting of triglycerides, cholesterol, phospholipids, and proteins made by intestinal cells--goes to lacteal.

Simple columnar epithelium.

Transverse colon because it is intraperitoneal

Mucous helps easy movement of fecal matter through colon.

Longitudinal bands of contracted muscle on large intestine.

Puckering/wrinkling of large intestine due to contracted muscle.

Intestinal gas--metabolic activities of bacteria attempting to breakdown indigestible carbs.

Convert bilirubin to sterobilinogens and urobilinogens, breaks down peptides that remain in feces.

Undigested food, products of bilirubin, epithelial cells, bacteria

Vitamin K and B5.

Gastroileal reflex
Peristalsis
Haustral churning
Mass peristalsis

Strong wave from transverse colon, initiated by food in stomach.

Forcing chyme into cecum.

Haustra of large intestine distend w/ fecal matter when contracted.

Stretch receptors in rectum when distended w/ feces.

Parasympathetic.

Sacral spinal cord. Yes.

Smooth muscle/skeletal muscle.

Initiated by stretch in rectum

Afferent fibers travel to sacral spinal cord

Efferent fibers come from spinal cord

Muscle wall contracts

Internal anal sphincter relaxes, and

External anal sphincter voluntarily controls expulsion of feces.