Digestive/Excretory/Reproductive System

Anatomy

Oral cavity

structure than functions in mechanical processing, moistening, and salivary mixing

Pharynx

structure that uses muscular propulsion of materials into the esophagus

stomach

structure that involves the chemical breakdown of materials via acid and enzymes

small intestine

the structure that conducts enzymatic digestion and absorption of water, organic substrates, vitamins, and ions

Pancreas

structure containing exocrine cells that secrete buffers and digestive enzymes

Gallbladder

structure that stores and concentrates bile

Liver

structure that secretes bile and stores nutrients

large intestine

structure that conducts the dehydration and compaction of indigestible materials in preparation for elimination

Serosa

the superficial layer that covers portions of the GI tract that are suspended in the abdominal cavity

Muscularis

layer of GI tract; is skeletal in the mouth, pharynx, top of esophagus for voluntary swallowing and is smooth in the rest of the tract to aid in breaking down food, mixing food with digestive enzymes, and propelling food along the tract

submucosa

layer of GI tract; contains areolar connective tissue that binds mucosa to muscularis, contains blood and lymphatic vessels that receive absorbed food

muscularis mucosae

thin layer of smooth muscle that forms small fold in the mucous membrane of stomach and small intestine; alters shape of intestinal lumen to increase surface area

lamina propria

layer of GI tract that contains blood and lymphatic vessels; binds epithelium to muscularis mucosae

myenteric plexus

within muscularis between longitudinal and circular smooth muscle; controls GI tract motility such as frequency and strength of muscularis contraction

submucosal plexus

located within submucosa; motor neurons supply secretory cells of mucosal epithelium, controlling secretions of GI tract organs

vagus nerve

nerve that supplies parasympathetic fibers to most of GI tract

endoderm

embryonic origin of the epithelial lining and glands of GI tract

mesoderm

embryonic origin of the smooth muscle and connective tissues of GI tract

mesentery

a double sheet of peritoneal membrane that suspends visceral organs and carries nerves, lymphatics, and blood vessels

peritoneum

largest serous membrane in the body

parietal peritoneum

lines walls of abdominal cavity

visceral peritoneum

covers some organs in abdominal cavity and is the serosa

greater omentum

drapes over transverse colon and coils of small intestine; contains adipose tissue that can expand and lymph nodes that contribute macrophages and antibody-producing plasmins that help contain infections of the GI tract

falciform ligament

attaches liver to anterior abdominal wall and diaphragm

lesser omentum

provides access for blood vessels entering and leaving the liver

mesentery proper

binds jejunum and ileum to posterior abdominal wall; also wraps around small intestine and returns to origin, forming a double-layered structure that provides stability and limited movement

mesocolon

binds transverse colon and sigmoid colon to posterior abdominal wall; allows movement as muscular contractions mix and move luminal contents along GI tract

submandibular gland

creates 65-70% of saliva; mostly composed of serous fluid and some mucous

amylase

enzyme in saliva that breaks down starch into maltose, maltotriose, and a-dextrin

parotid gland

creates 20% of saliva; most serous fluid that is slightly acidic from presence of bicarbonate and phosphate

sublingual gland

creates saliva that is composed of some serous fluid, but mostly mucous; creates 10-15% of saliva

primary dentition

teeth in mouth at 6 months of age that consists of the first and second deciduous molars

secondary dentition

teeth in mouth from ages 6-12 are deciduous; from age 17+ third permanent molars grow in

dentin

the mineralized matrix similar to bone that is the bulk of each tooth

incisors

the four front teeth that are used for cutting food

canines

4 teeth used for tearing food; also known as cuspids

premolars

8 teeth used to crush and grind food; also known as bicuspids

molars

12 teeth used for grinding food in the back of the mouth

esophagus

consists of nonkeratinized stratified squamous epithelium that creates prominent muscularis (forms an upper sphincter of skeletal muscle and a lower sphincter of smooth muscle)

deglutition

the swallowing process

buccal phase

phase in which bolus is forced to the back of the oral cavity and oropharynx by movement of tongue upward and backward against palate

pharyngeal phase

phase in which bolus stimulates receptors in oropharynx, sending impulses to deglutition center of medulla oblongata; impulses cause soft palate and uvula to move upward and close off nasopharynx

esophageal phase

phase in which bolus is moved down toward the stomach

peristalsis

progression of coordinated contractions and relaxations of circular and longitudinal layers of muscularis which pushes bolus inward

Cardia

part of stomach; surrounds the opening of the esophagus into the stomach

Atrium

part of stomach; connects to body of the stomach which is the mixing center

pyloric sphincter

the entrance into the duodenum from the stomach in which stomach contents can pass through

parietal cells

cells within the stomach that secrete hydrochloric acid; needed for vitamin B12 and HCl absorption

Chief cells

cells within the stomach that secretes pepsinogen and gastric lipase

G cells

cell of the stomach that secretes the hormone GastrinG

Gastrin

secreted by G cells; signals the pancreas to secrete enzymes

Propulsion

process in which each peristaltic wave moves gastric contents from body of the stomach and intensify as they reach the atrium

propulsion

process that continues until food particles are small enough to pass through the pyloric sphincterg

Gastric pit

Opening into the gastric glands; helps regulate the release of chyme into the duodenum

Carbonic anhydrase

located in parietal cells; catalyzes formation of carbonic acidca

carbonic acid

produces hydrogen for proton pumps that provide energy for digestion

bicarbonate

these ions exit the parietal cells in exchange for chlorine; this process can raise pH in blood and make urine more alkalinec

carbonic anhydrase

lack of this enzyme can result in higher pH during gastric digestion

emulsification

a process by the gallbladder; the breakdown of large lipid globules into a suspension of smaller lipid globules in which having a smaller size can allow pancreatic lipase to rapidly digest triglycerides

cholecystokinin

stimulates release of bile from gallbladder and common bile ducts; also stimulates pancreas to secrete digestive enzymes

secretin

stimulates bicarbonate and water volume to flow into intestines to neutralize acid

duodenal papilla

area within the duodenum that the contents from the common bile duct and pancreatic duct empty into

pancreatic acini

cells that compose the exocrine portion of the pancreas

pancreatic lipase

enzyme in the pancreas that digests fats

glucagen

located in pancreas; increases blood glucose lvelgl

glucagen

release of this occurs when blood glucose levels are low, when glycogen in liver needs to be broken down, and for gluconeogenesis from amino acids

insulin

this decreases blood glucose levels

insulin

release of this is stimulated when blood glucose levels are high and can facilitate glucose

hepatocyte

specialized type of epithelial cell that makes up 80% of the liver that secrete bile; forms 3D arrangements called hepaticlaminoe

bile canniliculi

small ducts between hepatocytes that collect produce bile before bile moves through ducts into the hepatic ducts

hepatic sinusoids

highly permeable blood capillaries between rows of hepatocytes that receive oxygenated blood from the hepatic artery and deoxygenated blood from the hepatic portal vein

Kupffer cells

cells a part of the hepatic phagocytotic system; phagocytizes aged red blood cells, white blood cells, and some bacteria

hepatocyte

cell that deaminates amino acids for ATP production; resulting ammonia is converted to urea and then secreted into urine

vasoactive intestinal peptide

produced in the gut, pancreas, and brain; assists in smooth muscle relaxation and increases motility

migrating mobility complex

aspect of peristalsis; begins in lower part of stomach and pushes chyme forward along a short stretch of small intestine before dying out

segementation

localized mixing contractions that occur in portions of intestine distended by a large volume of chyme; mixes the chyme with digestive juices and brings particles of food into contact with mucosa for absorption

duodenal ampulla

receives secretions from duodenum and pancreatic duct

Brunner's glands

duodenal glands within submucosa of duodenum which secrete alkaline mucous that helps neutralize gastric acid into the chyme

jejunum

contains intestinal villi that are most developed here in the intestine and are covered by simple columnar epithelium; also contains aggregated lymphoid nodules

jejunum

primarily functions in digestion and absorption of nutrients

plicae circulares

circumferential folds in the mucosa and submucosa of small intestine

small intestine

begins and completes digestion of nucleic acids

aminopeptidase

enzyme that cleaves off amino acid at the amino end of peptidase

carboxypeptidase

enzyme that splits off amino acid at carboxyl end of a peptide

depeptidase

enzyme that splits dipeptides into single amino acids

paneth cells

in crypts of small intestine, lyzosome is a host defense against bacteria via phagocytosis

sucrase

a brush border enzyme that breaks sucrose into a molecule of glucose and fructose

lactase

a brush border enzyme that digests lactose into a molecule of glucose and galactose

maltase

a brush border enzyme that splits maltose and maltriose into 2-3 molecules of glucose

gastroileal reflex

intensifies peristalsis in the ileum and forces chyme into the cecum

haustral churning

process in which haustra remain relaxed and becomes distended while they fill up; when distension reaches a certain point, the walls of the intestine contract and squeeze content into the next haustrum

mass peristalsis

strong peristaltic wave that begins at about the middle of the transverse colon and quickly drives contents of the colon into the rectum

teniae coli

runs most of the length of the large intestine; are portions of longitudinal muscles that are thickened

large intestine

primarily responsible for water and electrolyte absorption

ileocecal sphincter

valve that allows for materials from small intestine to pass to large intestine

mass peristaltic movement

movement that pushes fecal material from the sigmoid colon into the rectum; stimulates stretch receptors that result in defecation

dental caries

the gradual demineralization of enamel and dentin; caused by dextrin (a sticky polysaccharide produced from sucrose causing bacteria to stick to teeth)

Peridontal disease

inflammation and degeneration of gingivae, alveolar bone, peridontal ligament, and cementum

peptic ulcer

crate-like lesion in membrane of GI tract that is exposed to gastric acid juice

Helobacter pylori

bacterium that produces urease which splits urea into ammonia and carbon dioxide