anatomy block 5 exam

gastrointestinal tract

tube that extends from mouth to anus

Peristalsis

Involuntary waves of muscle contraction that keep food moving along in one direction through the digestive system.

accessory digestive organs

Not part of GI tract

teeth, tongue, salivary glands, liver, gallbladder, pancreas

Functions of the digestive system

digestion, absorption, elimination

Digestion

Breaking down food

mechanical and chemical digestion

mechanical digestion

Physical breakdown of food into smaller pieces.

chemical digestion

Enzymes break down food into smaller molecules

Absorption

water and food molecules pass through the intestines and move into other structures

GI lymphatics (lacteals)

absorb dietary lipids and lipid-soluble vitamins

blood vessels

absorb digest nutrients

Elimination

Act of removal of materials from the body

abdominopelvic cavity

lined by peritoneum

parietal peritoneum

lines the abdominal wall

visceral peritoneum

covers abdominal organs

peritoneal cavity

space between the parietal and visceral peritoneum

parasympathetic effect on digestive system

increase of all digestive activity - more intestinal movements, more pancreatic enzyme secretion, more stomach acid secretion.

sympathetic effect on digestive system

inhibits all - glands, GI movements, etc.

oral cavity

epithelium: non keratinized stratified squamous epithelium

Contains palate

palate

hard and soft palate and uvula

hard palate

anterior portion, supported by bone

palatine maxilla

bones of the hard palate

soft palate

posterior portion, formed from skeletal muscle

uvula

stops food from going into nasal cavity

teeth

~32 permanent teeth

2 incisors

1 canine

2 premolars

3 molars

per half of upper or lower

kids teeth

20 deciduous teeth

no third molar and no pre molars

tongue

Skeletal muscle, covered with mostly nonkeratinized stratified squamous epithelium

perceives taste and mechanical digestion

motor nerve for the tongue

Hypoglossal (CN 12)

taste nerve for the tongue

facial (CN 7) and glossopharyngeal (CN 9)

sensation nerve for the tongue

trigeminal (CN 5) and glossopharyngeal (CN 9)

salvatory glands

parotid, sublingual, submandibular

parotid gland

salivary gland within the cheek, just anterior to the ear

submandibular gland

a salivary gland inside the lower jaw on either side that produces most of the nocturnal saliva

sublingual gland

salivary gland under the tongue

saliva function

dissolves food, moisten food, cleanses mouth, chemical digestion, inhibits bacterial growth

Pharynx

throat, skeletal muscle tube that connects nasal cavity to larynx and esophagus

Function: propels food and drink to esophagus or air to larynx

Voluntary swallowing

Histology of GI tract

1. mucosa

2. submucosa

3. muscularis externa

4. serosa

mucosa

The innermost layer of the human digestive tract

contains the lamina propria and muscularis mucosae

lamina propria of mucosa

areolar connective tissue

muscularis mucosae

thin layer of smooth muscle

Submucosa

connective tissue

Contains major blood vessels

muscularis

typically contains 2 layers of smooth muscle: inner circular layer and outer longitudinal layer

Exception: esophagus has two layers of skeletal and smooth muscle; stomach has 3 layers of smooth muscle

Responsible for peristalsis

serosa or adventitia

outermost layer

serosa = visceral peritoneum + areolar CT

adventitia = areolar CT only

esophagus

A muscular tube that connects the pharynx to the stomach

Function: propels food to the stomach

esophagus histology

mucosa: nonkeratinized stratified squamous epithelium

muscularis: 2 layers of muscle

upper 1/3: skeletal muscle

middle 1/3: skeletal and smooth muscle

lower 1/3: smooth muscle only

reflux esophagitis

The backward flow of gastric acids into the esophagus

Risk: overweight, smoking, large meals before bed

stomach

churns food (mechanical digestion) and mixes it with gastric juices (chemical digestion)

Connects esophagus and duodenum

upper left of abdomen

stomach histology

Mucosa: simple columnar epithelium (contains gastric pits)

Muscularis: 3 layers of smooth muscle (innermost oblique, inner circular, and outer longitudinal)

peptic ulcer

erosion of wall of stomach or duodenum

caused by: helicobacter pylori infection

small intestine function

finishes the chemical digestion process, absorbs most (90%) of all nutrients

small intestine gross anatomy

duodenum, jejunum, ileum

duodenum

first part of the small intestine, c shaped

Receives chyme from stomach

receives bile and pancreatic enzymes through duodenal papilla

duodenal papilla

the raised area where the common bile duct and pancreatic duct enter the duodenum

Jejunum

second part of the small intestine, huge surface area

Ileum

3rd part of small intestine, last 3/5 of small intestine, connects to cecum of large intestine, few folds but contains MALT

small intestine histology

mucosa: simple columnar epithelium with goblet cells and microvilli

right under is the muscularis mucosa

circular folds of small intestine

folds of mucosa and submucosa

increases surface area so nutrients can be absorbed and slows down chyme allowing for mixing

villi of small intestine

only on mucosa folds

increases surface area

Lacteal (of villi of small intestine)

absorb lips and lipid soluble vitamins

large intestine function

absorbs water and electrolytes, storage for feces

large intestine gross anatomy

cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal

cecum

connects to ileum, vermiform appendix attaches to cecum

ascending colon

right side of body, travels up

transverse colon

runs from right to left side of body

descending colon

left side of body, travels down

sigmoid colon

in pelvic cavity, S-shaped

Rectum and anal cavity

terminal portion of large intestine, feces leaves the ana canal through anus

large intestine histology

Mucosa: simple columnar epithelium Contains goblet cells

Muscularis: 2 layers of smooth muscle, outer longitudinal layer consist of teniae coli

haustra of large intestine

segmental portion of the intestine

colorectal cancer

cancer in large intestine

arrive from polyps from mucosa

Liver function

Produces and secretes bile, processes products of digestion, and stores glycogen

Liver gross anatomy

Lobes: right (largest), left, quadrate, and caudate

Hepatic portal vein, hepatic artery proper, and common hepatic duct

right lobe of liver

largest lobe of the liver

left lobe of liver

smaller lobe of liver

quadrate lobe of liver

next to gallbladder and square

caudate lobe of liver

A small lobe of the liver located posteriorly and below quadrate lobe

lobules of liver

Hexagonally shaped functional units which consist of hepatocytes, central vein, portal triad

hepatocytes (liver)

make bile, exits the liver via bile duct

central vein of liver lobule

form hepatic veins and drains blood out of liver to IVC

portal triad of liver lobule

hepatic artery, hepatic portal vein, bile duct

branch of hepatic portal vein

- blood from the digestive tract

- brings nutrients into the sinusoids

branch of hepatic artery

- fresh oxygenated blood into liver

bile duct

A tube that carries bile from the liver and gallbladder to the intestine

Gallbladder

underneath liver, stores and concentrates bile secreted by liver

gallstones

condensations of bile material into stones

pancreas

behind the stomach, contain acinar cells

acinar cells

secrete pancreatic juice

Pancreatic Juice

neutralizes the acidic chyme

leaves via a pancreatic duct

biliary apparatus

a network of "tubes" that transport bile and pancreatic juices to the duodenum

common hepatic duct

Formed by right and left hepatic ducts

cystic duct

Duct leading from the gallbladder to the common bile duct; carries bile

common bile duct

carries bile from the liver and gallbladder to the duodenum

Formed from cystic duct and common hepatic duct

pancreatic duct

conducts pancreatic juice from the pancreas to the small intestine

major duodenal papilla

opening of the pancreatic duct and common bile duct into the duodenum

celiac trunk

Major artery supplying abdominal organs.

superior mesenteric artery

large abdominal artery; feed large and small intestine

inferior mesenteric artery

Supplies arterial blood to the large intestine.

hepatic portal system

veins that drain blood from GI tract directly to liver

splenic vein, superior mesenteric vein, inferior mesenteric vein and hepatic portal vein

splenic vein

drains the spleen, pancreas, and stomach

superior mesenteric vein

drains small intestines and ascending colon

inferior mesenteric vein

drains distal portion of large intestine