A7 E2: The Digestive System

circular folds 2 funcitons

- 1 cm tall - increase absorptive surface area - for chyme to spiral through the intestinal lumen, slowing its movement and allowing time for complete absorption of nutrients

Explain the mechanical breakdown, propulsion, digestion and absorption in the large intestine

- Digestion: Some remaining food residues are digested by enteric bacteria (which produce k and b vitamins) - Absorption: absorbs most remaining water, electrolytes (largely NaCl) and vitamins produced by bacteria - Propulsion: propels feces toward rectum by haustral churning and mass movements - Defecation: Reflex triggered by rectal distension, eliminates feces from body

Name the structures within the villus that receive absorbed nutrients

- End products of carbs and protein digestion are absorbed into the capillary network within the villus - lacteals absorb fats

The two ventral mesenteries

- Falciform ligament: binds anterior aspect of the liver to the anterior abdominal wall - lesser omentum: runs from liver to the lesser curvature of the stomach (liver thinks "oh man" a lot of the time so makes you puke)

How does the duodenum recieve digestive enzymes?

- From the pancreas via the main pancreatic duct - Bile from the liver and gallbladder via the bile duct

Explain the mechanical breakdown, propulsion, digestion and absorption in the stomach

- Mechanical breakdown and propulsion: peristallic waves mix food with gastric juice and propel it into the duodenum - Digestion: pepsin breaks down proteins while gastric lipase digests fats. - Absorption: a few fat-soluble substances (aspirin, alcohol and some drugs)

Functions of the different parts of the portal triad

- arterial blood supplies the hepatocytes with oxygen - blood from portal vein delivers substances from the intestine for processing by the hepatocytes - bile duct carries bile away from the intestine

Chief (zymogenic) cells

- basal parts of glands - make and secrete pepsinogen enzyme (pepsin) - gastric lipase (fat digestion) the chief is fat because he loves pepsi too much

Muscularis externa function

- circular layer squeezes the gut tube and the logitudinal layer shortens it, leading to peristalsis and segmentation

What is unique about the muscularis externa of the stomach?

- contains additional layer of smooth muscle: run obliquely (slant) oblique fibers

Smooth muscle fibers

- elongated cells with one central nucleus. No striations or sarcomeres. - filled with myofilaments that contract by the sliding filament mechanism - involuntary

Explain the differences in wall structure of large and small intestine, and give reasons for why the structure is different.

- goblet cells moer abundant in large intestine: secrete large amounts of lubricating mucus that eases the passage of feces - L intestine absorptive cells are called colonocytes and take in water and electrolytes: not nutrients. - villi are absent in the small intestine, which reflects the fact that fewer nutrients are absorbed in the large intestine - The lamina propria and submucosa of the l intestine contain more lymphoid tissue b/ of extensive bacterial flora of the large intestine

Dorsal Mesentaries

- greater omentum: connects the greater curvature of stomach to the posterior abdominal wall in a roundabout way - Transverse mesocolon: transverse colon is held to the posterior abdominal wall - Sigmoid mesocolon: connects the sigmoid colon to the posterior pelvic wall

Functions of mesenteries

- hold organs in place (intraperitoneal organs to the body wall) -store fat - provide a route for circulatory vessels and nerves to reach the organs in the peritoneal cavity

Name the intraperitoneal organs and their mesenteries

- liver (falciform ligament and lesser omentum) - Stomach (greater and lesser omentum) - Ilium and jejunum (mesentary proper) - Transverse colon (transverse mesocolon) -Sigmoid colon (sigmoid mesocolon)

Mucosa: lamina propria functions

- loose areolar or reticular connective tissue - capillaries nourish the lining epithelium and absorb digested nutrients - contains MALT (tissue that defends against invasion by bacteria and other microorganisms)

Teniae coli "ribbons of the colon"

- maintain muscle tone, and cause the large intestine to pucker into sacs of haustra

Jejunum function

- middle portion of small intestine - primary region for chemical digestion and nutrient absorption

Parietal cells

- middle regions of glands - produce HCL - secrete gastric intrinsic factor (protein nec for b12 absorption) Parents always do acid and left their 12 year old to care for himself

Metabolic functions of the liver

- picks up glucose from nutrient-rich blood returning from the alimentary canal and stores this carb as glycogen for subsequent use by the body - processes fats and amino acids and stores certain vitamins and nutrients - detoxifies drugs, metabolites and poisons - makes the blood plasma proteins (albumins and globulins, proteins for b clotting) - phagocytosis of debris and breakdown and recycling of aged erythrocytes and formed elements

Cirrhosis

- progressive inflammation of the liver resulting from chronic alcoholism or hepatitis - even though alcohol poisoned hepatocytes are continuously replaced, the liver's connective tissue regenerates faster so the liver becomes fibrous and fatty and its function declines. Cuases hypertension in the hepatic portal vessels

Gastric intrinsic factor

- protein necessary for vitamin B12 absorp by the small intestine. B12 is used in the manufacture of red blood cells

Explain the mechanical breakdown, propulsion, digestion and absorption in the small intestine and associated accessory organs (liver, gallbladder, pancreas)

- segmentation by smooth muscle mixes content with digestive juices and propels food along small intestine through ileoccecal valve at a slow rate - Digestion: Bile from liver and gallbladder emulsifies fat; digestive enzymes from pancreas and brush border emzymes attached to microbilli membranes complete digestion of all classes of food - Absorption: Breakdown products of carbohydrate, protein, fat and nucleic acid digestion, plus virtamins, electrolytes and water are absorbed by active and passive mechanisms

Mucosa: Muscularis mucosae functions

- thin layer of smooth muscle - produces local movements of the mucosa

Mucous neck cells (location and function)

- upper ends of gastric glands in the fondus and body area of stomach - Secrete different mucus than surface cells (acidic fluid containing mucin)

Esophagus innervation

- vagus nerve (peristalsis)

Features typical of protein-secreting cells

- well developed rough er and golgi apparatus - secretory granules in the apical cytoplasm

What causes acid reflux?

-problem with cardiac sphincter -hiatal hernea

The organs of the digestive system perform what six essential food-processing activities

1.) Ingestion 2.)propulsion 3.) Mechanical breakdown 4.) digestion 5.) absorption 6.) defecation

Two other epithelial cell types that occur in the gastric glands, but also extend beyond these glands

1.) enteroendocrine cells (hormone-secreting cells) - gastrin signals HCL secretion when food enters the stomach - pyloric region 2.) Stem cells (replacing the entire lining epithelium of mucus-secreting cells every 3-7 days.)

Defecation reflex

1.) feces move into and distend the rectum, stimulating stretch receptors there that transmit afferent signals to the spinal cord neurons 2.) parasympathetic motor (efferent) fibers stimulate contraction of the rectal walls and relaxation of the internal anal sphincter 3.) if it's convenient to defecate, the external anal sphincter relaxes so that feces may pass

Gallbladder wall layers

1.) mucosa consisting of a simple columnar epithelium and a lamina propria 2.) one layer of smooth muscle 3.) thick outer layer of connective tissue that is covered by a serosa wherever it is not in direct contact with the liver

Gastrin secretion will stop when the stomach pH reaches _____.

1.5

Stomach easily holds ______ of food and has max capacity of ___________.

1.5 liters, 4 liters (1 gallon)

During the __________ hours that the residue remains in the large intestine, __________________ occurs.

12-24 hours; little additional breakdown of food (except for the small amount of digestion performed by the many bacteria living there.

Living donor liver transplants. Grow back to normal size over the next _________.

2 months

The esophagus is how long?

25-28cm long

Duodenal papilla wher ebile and pancreatic secretions enter the duodenum is located between the _____ and _____ parts of the duodenum

2nd (desending) and 3rd (transverse)

What is the typical life span for an intestinal epithelial cell? How are the cells of the epithelium replaced?

3 to 6 days. Replaced by cells from the rapidly dividing undifferentiated epithelial cells that line the intestinal glands.

Food remains in the stomach for how long

4 hours

The alimentary tube is around _____ meters long.

9

During development, when is the lumen open?

9th week

The submucosal nerve plexus of the intestine A.) innervates the mucosa layer B.) lies in the mucosa layer C.) controls peristalsis D.) contains only motor neurons

A

Organs of the digestive system can be divided into what two main groups?

Alimentary canal (aliment = nourishment) and the accessory digestive

Explain the patter of the wall specialization as the small intestine continues.

Because most absorption occurs in the proximal region of the small intestine, these specializations decrease in number toward the distal end.

Explain the pathway of the large intestine in the order of the residue entering the cecum from the ileum

Cecum --> ascending colon --> right colic flexure (hepatic flexure) --> transverse colon --> left colic (splenic flexture --> descending colon --> S-shaped sigmoid colon --> rectum --> anal canal

Paneth cell location and function

Cell of small intestine that secretes substances that destroy bacteria (Think of a frying pan: kinda looks like bacteria with tail, or think "Paneth" kinda sounds like "path" and pathology has to do with bacteria)

What amplifies the small intestines absorptive surface?

Circular folds, villi and extensive microvilli

Midgut organs

Duodenum (3,4), jejunum, ileum, cecum, appendix, ascending colon and transverse colon (proximal 2/3)

When food enters the stomach, how does it know to secrete HCL?

Enteroendocrine cells in the pyloric region secrete gastrin hormone which signals parietal cells to secrete HCL

T/F Mechanical vs Chemical digestion: Both digestive processes goal is to break food into smaller pieces

False, this is mechanical digestions goal Chemical digestion involves breaking down the food into simpler nutrients that can be used by the cells.

Large intestine anatomy

Frames the small intestine on 3 1/2 sides, forming an open rectangle. Subdivisions: cecum, appendix, colon, rectum and anal canal

Infection promotes gastric inflammation, neutralizes gastric acid degrades mucous (eats through mucous to bind to epithelium, less protection from stomach acid)

H pylori

Causes peptic ulcers

Heliobacter Pylori Adherence to gastric mucosa

Why are liver sinusoids lined by an exceptionally leaky, fenestrated endothelium?

Hepatocytes require proximity to such a large blood supply because so many of their functions depend on interactions with the fluid portion of blood

Retroperitoneal

In direct contact with the posterior abdominopelvic walls (only covered with visceral peritoneum on anterolateral surfaces)

Manufacture some essential vitamines, which the intestines absord (e.g. vitamin K)

Intestinal flora

consequences of acid reflux

It can cause the inner lining of the esophagus to be eaten away (barrett esophagus) -metaplastic change of mucosa from stratified squamous to specialized columnar (barrett esophagus)

Ileum function

Las

The typical digestive mucosa contains what three sublayers

Lining epithelium, lamina propria and a muscularis mucosae

What is unique about the rectums wall?

Longitudinal muscle layer is complete and well developed

Parietal cell unique cell structure

Look like pitchfork with long microvilli (large surface area to enable rapid movement of H and CL out of cell) - many mitochondria

Help determine which kinds of bacteria live in the intestinal luen

Mature Paneth cells (base of intestinal crypt)

Double layer of peritoneum (sheet of two serous membranes fused together)

Mesentery

Digestion occurs mainly in

Mouth, accessory organs (tongue, salivary glands), stomach, small intestine and first part of large intestine

Mechanical breakdown occurs mainly in

Mouth, stomach and small intestine

Twitching of what muscle layer would dislodge sharp food particles that become embedded in the mucosa?

Muscularis mucosae

Hepatopancreatic ampulla

Opens into the duodenum via a mound called the major duodenal papilla

Oversecretion of stomach acid can result in what?

Peptic ulcers

Consists of adjacent segments of alimentary tract organs alternately contract and relax

Peristalsis

_______________ propels chyme through the small intestine in about ________ hours

Peristalsis; 3-6

Injury to the spleen or liver can cause extensive internal bleeding. Where would blood collect from such an injury?

Peritoneal cavity (b/ spleen and liver are within peritoneal cavity

The digestive organs in the abdominopelvic cavity all develop surrounded by __________________ and the ___________________.

Peritoneum (visceral - external surface of organs and parietal - lines body wall) and the peritoneal cavity (slitlike potential space between the visceral and parietal peritoneum

Goblet cell in small intestine function

Secretes mucus

Peritoneum is a ______________ that lines ____________ and covers ______________

Serous membrane that lines the abdominopelvic cavity and covers the surfaces of the organs in this cavity

Gallbladder epithelium and its associated function

Simple columnar cells of the lining epithelium concentrate the bile by absorbing some of its water and ions

Small intestine epithelium structure and function

Simple columnar: it absorbs nutrients from the lumen of the intestine.

Mesentery proper

Suspends most of the small intestines from the posterior abdominal wall

Organs of the accessory digestive organs

Teeth, tongue, gallbladder and large digestive glands (salivary glands, liver and pancreas)

Food material in the alimentary canal is technically considered to be outside the body, why is this?

The canal is open to the external environment at both ends (mouth and anus)

During toilet training, children learn to control what?

The external anal sphincter

Propulsion

The movement of food through the alimentary canal. Includes swallowing and peristalsis (wavelike contractions of smooth muscle)

Describe how the small intestine and large intestine connect

The opening of the ileum into the cecum;s medial wall is surrounded internally by the ileocecal valve

What allows feces from being passed along with gas?

The rectal valves

Segmentation

The rhythmic local constricitons of the intestine. Mixes food with digestive juices and increases the efficiency of nutrient absorption by repeatedly moving diff parts of the food mass over the intestinal wall

Name the vessels and ducts that pass through the porta hepatis. indicate what is found within each structure and whether its content goes into the liver or away from the liver

The right and left hepatic arteries carry oxygen-rich blood into the liver; the right and left branches of the hepatic portal vein carry nutrient-rich blood into the liver; and the right and left hepatic ducts carry bile out of the liver.

Explain how the anal canal is a zone of epithelial transition WHY (STILL NEED TO FIND ANSWER)

The simple columnar epithelium of the intestine abruptly changes to stratified squamous epithelium near the level of the pectinate line

Absorption

Transport of digested end products from the lumen of the ali canal into the blood and lymphatic capillaries located in the wall of the canal

Hindgut

Transverse colon (disal 1/3), descending and sigmoid colon, rectum

T/F Mechanical vs Chemical digestion: both occur in the stomach, small intestine and large intestine.

True

T/F Mechanical vs Chemical digestion: Both digestive processes start in the mouth

True mechanical=chewing chemical=saliva

Cell types found within the intestinal crypts

Undifferentiated epithelial cells (line the intestinal crypts and renew the mucosal epithelium every 3-6 days) - Mature Paneth cells: found at base of the crypt secrete enzymes that destroy certain bacteria

Ventral vs dorsal mesenteries

Ventral: extends from the stomach and liver to the anterior abdominal wall Dorsal: extending from the posterior abdominal wall to the slimentary canal

Peristalsis

Wavelike contractions of smooth muscle that squeeze foodstuffs through the alimentary canal

Differentiate the abdominal cavity from the peritoneal cavity

abdominal cavity is the portion of the ventral body cavity extending from the diaphram to the pelvis. Peritoneal cavity is the space between the parietal and visceral serous membranes.

Main function of the large intestine

absorb water and electrolytes from the digested mass, resulting in semisolid feces

Mucosa: lining epithelium fuction

absorbing nutrients and secreting mucus.

Colonocyte location and function

absorbs water, electrolytes and vitamins

Of the basic digestive processes, the one in which nutrients enter capillaries is called

absorption

The wall of the small intestine contains what cells

absorptive enterocytes, scattered goblet cells and enteroendocrine cells

Which cells in the pancreas produce and secrete digestive enzymes? Where do these secretions empty into the alimentary canal?

acinar cells. duodenum

Anorectal angle

acute angle between the anus and the rectum that contributes to fecal continence

Releases mucus when they are compressed by feces, providing lubrication that eases fecal passage during defecation

anal sinuses

Protein digestion begins a.) in the mouth by saliva b.) in the stomach my pepsin

b

Protects the stomach wall from the destructive effects of acid and pepsin in the lumen

bicarbonate-buffered mucus

What do the surface cells that line the stomach produce?

bicarbonate-buffered mucus

Large midportion of the stomach

body

Gastric glands, which produce most of the gastric juice, are abundant in which of the following regions of the stomach?

body, fondus

ring-shaped zone encircling the cardial orifice

cardia

Function of the right and left hepatic ducts

carry bile from the respective liver lobes - they fuse to form the common hepatic duct

The large intestine begins with a saclike ____________.

cecum

The pancreas autonomic nerves are from the ________

celiac plexus

The arteries to the stomach arise from the ____________

celiac trunk

Hepatocytes have a great capicity for ______________ and _______________.

cell division and regeneration half of person's liver were removed it would regenerate in a few weeks!

Mechanical processes include what?

chewing, churning food in the stomach and segmentation (rhythmic local constrictions of the intestine)

Gastric enzymes are secreted by the ________ cells

chief

Bile is the normal vehicle in which ___________ is excreted from the body

cholesterol

The ____________ and _____________ churn and pummel food into smaller fragments. The _____________ jackknife the stomach into a V shape to move the chyme into the small intestine

circular and longitudinal layers; oblique fibers

Enterocyte location and function

completes digestion and absorbs nutrients across microvilli (small intestine)

The exocrine glands of the pancreas are simple/compound tubular/acinar

compound acinar

Acinar cells unique

contain elaborate rough ER and golgi apparatus

chyme

creamy mass consisting of partially digested food and stomach juices

Which of the following statements about smooth muscle is false? a.) smooth muscle cells are called fibers b.) most smooth muscle cells, like cardiac muscle cells, are joined by gap junctions c.) smooth muscle cells have a single, centrally located nucleus d.) contraction of smooth muscle is stimulated exclusively by involuntary nervers e.) smooth muscle tissue found in the wall of hollow organs is arranged in sheets

d

Cause of most Gastric and Duodenal ulcers due to a

decrease in mucosal protection against gastric acid

inferior mesenteric artery supplies arterial blood to what digestive organs?

descending colon, rectum

Defecation process also involves the voluntary contraction of

diaphragm and abdominal wall muscles and levator ani muscles

Intraperitoneal organs

digestive organs that keep their mesentery. - liver, stomach, ileum and jejunium, transverse colon and sigmoid colon

What happens with absorbed fats in the small intestine?

don't go directly to the liver, but rather travel through the lymphatic vessels and empty into the venous system. Eventually are returned to liver for detoxification

The gallbladder and large digestive glands of the accessory digestive system is connected to the alimentary canal by what?

ducts

Pancreatic enzymes are activated in the _______________.

duodenum

Upper right quadrant of the abdomen and is C shaped

duodenum

Subdivisions of the small intestine

duodenum (5%), jejunum (40%) and the ileum (60%)

Secondarily retroperitoneal organs (lack mesenteries)

duodenum, ascending colon, descentding colon, rectum, pancreas

When do the longitudinal folds of the mucosa and submucosa of the esophagus flatten out?

during passage of a bolus

The many ___________ in the ______________ enable the alimentary canal to return to its shape after food material passes through it

elastic fibers; submucosa

Bile function

emulsify fats in the small intestine; break up fatty nutrients into tiny particles

relating to or occurring in the intestines.

enteric

Cells of the small intestine

enterocyte, goblet cell, enteroendocrine cell and paneth cells

The esophagus passes through the _______________ in the diaphragm to enter the abdomen

esophageal hiatus

Prevents regurgitation of acidic stomach juices into the esophagus

esophageal hiatus and cardiac sphincter

Muscular tube that propels swallowed food to the stomach

esophagus

Foregut

esophagus, stomach, gallbladder, liver, spleen, duodenum (1, 2)

The stomach extends from ________ to _________

esophagus; small intestine

What is unique about the microvilli in the small intestine?

exceptionally long and densely packed

Hydrochloric acid in the stomach functions primarily to: A.) facilitate lipid digestion B.) facilitate protein digestion C.) facilitate carbohydrate digestion D.) hydrolyze peptide bonds

facilitate lipid digestion

Epiploic appendages

fat-filled pouches of visceral peritoneum that hang from the large intestine. significance unknown

When _____________ from a meal enters the ______________, the gallbladder's muscular wall contracts in response to the hormone _______________ which is released from the ______________. The sphincters at the end of the duct system relax, and bile is expelled from the gallbladder.

fatty chyme; duodenum; cholecystokinin, enteroendocrine cells in the duodenum.

Trace the path of blood drained from the digestive tract through a liver lobule

from the hepatic portal vein, to the portal venules in the portal triad at the periphery of a liver lobule, through the liver sinusoids, into the central vein of the lobule

stomach's dome, tucked under diaphragm

fundus

What accessory organ has fewer layers than the wall of the alimentary canal?

gallbladder

bile is a green alkaline liquid that is stored in the _______________ and secreted into the _______________.

gallbladder; duodenum

Surface mucous cells invariably line the gastric pits, but the cells lining the __________ vary among the different regions of the stomach

gastric glands

The surface of the stomach mucosa is dotted with millions of what?

gastric pits, which open into tubular gastric glands

Hormone that increases the activity of parietal and chief cells

gastrin

Glands in the _____________ produce enzymes and other substances and secrete them into the __________________, where they carry out digestion

gastrointestinal tract and the accessory organs; lumen of the alimentary canal

Mesenteries that connect to the stomach

greater and lesser omenta (named for their attachment to the greater and lesser stomach curvatures)

Convex left surface of the stomach

greater curvature

Attaches greater curvature of the stomach; has the most fat

greater omentum

lacteal

he lymphatic vessels of the small intestine that absorb digested fats.

Functional unit of the liver

hepatic lobule

All metabolic functions of the liver are carried out by a type of cell called a

hepatocyte (liver cell)

liver lobules

hexagonal, consists of plates of liver cells (hepatocytes). Think of a thick paperback book opened so wide that its two cover touched. spreading of pages represents the plates of hepatocytes and the hollow cylinder formed by the rolled spine represinting the central vein

Destroys harmful bacteria in the food in the stomach

hydrochloric acid

superior mesenteric artery supplies arterial blood to what digestive organs?

ileum, ascending colon, cecum

Which muscles constrict to prevent air from entering the esophagus during breathing?

inferior constrictor

The wall of the anal canal contains two sphincter muscles:

internal anal sphincter of smooth muscle: contracts involuntarily to prevent feces from leaking from the anus between defecations and external anal sphincter of skeletal muscle: voluntarily contracted to inhibit defecation

Enterocytes

intestinal absorptive cells, are simple columnar epithelial cells found in the small intestine.

Common features of the small and large intestines

intestinal crypts

Secretes intestinal juice (watery liquid that mixes with chyme in the intestinal lumen)

intestinal crypts (mucosa between the villi)

The last major organ in the alimentary canal

large intestine

Describe the material that reaches the large intestine

largely digested residue that contains few nutrients

The quadrate lobe and caudate lobe of the liver are considered part of the _________ lobe, with which they share nerves and vessels

left

The stomach is located in the

left hypochondriac, epigastric, and umbilical regions of the abdomen.

Concave right margin of stomach

lesser curvature

Runs from the stomach's lesser curvature to the fissure of the liver

lesser omentum

What makes the blood proteins?

liver

What processes fats and amino acids and stores some vitamins?

liver

Between plates of the hepatocytes are large capillaries called

liver sinusoids (recieve blood from both the portal arteriole and venule and carry blood inward to reach the central vein.)

The bv that drain the small intestine carry absorbed nutrients to the __________ via the ______________.

liver; hepatic portal system remember NOT absorbed fats

Esophageal cardiac glands

located in the lamina propria and secrete neutral mucus that protects the esophagus from acidic gastric juices.

Esophageal glands proper

located in the submucosa and secrete acid mucin for lubrication.

anal columns

longitudinal folds of mucosa on the superior half of the anal canal

Smooth muscle contracts for extended periods at _________________ and without ___________

low energy; fatigue

Appendix has large masses of _____________ in its wall. What is its proposed function?

lymphoid tissue. Safe haven for beneficial bacteria that inhabits the large intestine.

what ducts join to form the hepatonpancreatic ampulla that empties into the duodenum

main pancreatic duct + bile duct = hepatopancreatic ampulla

Acinar glands

make, store and secrete at least 22 kinds of pancreatic enzymes

Secondarily retroperitoneal organs

mesentery at first but end up against the posterior abdominal wall and are fused to the dorsal abdominal wall, in the process losing their mesentery and lodging behind the peritoneum.

Barrett's esophagus

metaplastic change of mucosa from stratified squamous to specialized columnar in the distal part of esophagus

The apical surfaces of the absorptive enterocytes have many ______________.

microvilli

Enterocytes contain many ____________ and an abundant _______________.

mitochondria;ER

Organs of the alimentary canal (GI tract)

mouth, pharynx, esophagus, stomach, small intestine and large intestine, anus

From the lumen outward name the tissue layers of the wall of the alimentary canal

mucosa, submucosa, muscularis externa and serosa

Layers of esophagus

mucosa, submucosa, muscularis externa, adventitia

MALT is found in the ________________ throughout the intestine

mucosal layer

The cells of the gastric glands in the fundus and body include

mucous neck cells, parietal cells and chief cells

Sympathetic stimulation of the muscularis externa promotes

muscular inhibition and relaxation

What layer of the alimentary canal has a circular and longetudinal layer of smooth muscle?

muscularis externa

Myenteric nerve plexus

nerve fibers and associated ganglia between the inner circular layer and outer longitudinal layer of muscle

Esophagus epithelium structure and function

nonkeratinized stratified squamous epithelium protects underlying tissues in areas subject to abrasion

Is both an exocrine and endocrine gland

pancreas

Most digestive enzymes that operate within the small intestine are secreted by the ____________.

pancreas

What digestive system organs are located in the abdominal cavity but are not intraperitoneal?

pancreas, duodenum, ascending and descending colon and rectum

zymogen granules

pancreatic enzymes are stored here in an inactive form

Contains enzymes that complete the final stages of the breakdown of nutrient molecules

plasma membrane of the microvilli in the small intestine

Where most the major vessels and nerves enter and leave the liver

porta hepatis

At every corner of the liver lobule is a portal triad that contains three main vessels

portal arteriole (branch of hapatic artery), portal venule (branch of hepatic vein), and a bile duct.

oxygen-poor and nutrient-rich blood drained from the digestive tract by the

portal vein

correctly describes the flow of blood through the classical liver lobule

portal venule to sinusoids to central vein to hapatic vein to inferior vena cava portal arteriole to sinusoids to central vein to hepatic vein

Pancreas exocrine function

produce and secrete digestive enzymes and bicarbonate, collectively called pancreatic juices, into the duodenum via the pancreatic duct most of the enzymes that digest foodstuffs in the small intestine

Digestive function of the liver

produce bile

Esophagus specialzed for ____________ from what

protection from microorganism invasion, mechanical damage by unprocessed food, chemical damage by acid of stomach

Pepsin

protein-digesting enzyme in stomach that functions only under acidic conditions

Plexus of meissner

provides motor innervation to both layers of the muscular layer of the gut, having both parasympathetic and sympathetic input

bottom of the stomach

pyloric (atrium and canal)

Area of stomach where the cells of the glands are primarily mucous cells

pyloric and cardiac parts

Controls entry of chyme into the intestine

pyloric sphincter

What part of the large intestine has no teniae coli?

rectum

hepatic

relating to the liver

Organs are described as ____________ if they are located behind the parietal peritoneum.

retroperitoneal Organs that were once suspended within the abdominal cavity by mesentery but migrated posterior to the peritoneum during the course of embryogenesis to become retroperitoneal are considered to be secondarily retroperitoneal organs.

Gallbladder is located on the _______ lobe of the liver

right

Stomach arteries and their corresponding veins

right and left gastric (portal veins), short gastric (superior veins) and right and left gastroepoploic arteries (mesenteric veins)

The wide base of the liver faces _________ and the narrow apex les just inferior to the level of the ______________.

right; left nipple

Flatten as the stomach fills to expand for mroe food

rugae (wrinkles)

Goblet cells in the small intestine function

secrete onto the internal surface of the intestine a goat of mucus that lubricates the chyme and forms a protective barrier that prevents enzymatic digestion of the intestinal wall

Gastric intrinsic factor

secreted by parietal cells, nec for b12 absorption

Pancreas endocrine function

secretes insulin and glucagon, which lower and raise b sugar respectively.

The contractions of the stomach are inhibited by

secretin

Consists of nonadjacent segments of alimentary tract organs to alternately contract and relax

segmentation

What layer of the alimentary canal is formed of simple squamous epithelium underlain by a thin layer of areolar c tissue?

serosa

Which gastrointestinal layer is characterized by having tough, fibrous connective tissue?

serosa

Parts of the alimentary canal that are not associated with the peritoneal cavity lack a ____________ and have a _____________.

serosa; adventitia (ordinary fibrous c tissue) - ex: thorax and esophagus

Connects large intestine to pelvic wall

sigmoid mesocolon

Stomach epithelium structure and fuction

simple columnar epithelium (specialized for secretion) where it secretes acid, digestive enzymes and mucous.

The mucosa of the stomach is ______________ epithelium and consists entirely of cells that __________________.

simple columnar; secrete a coat of bicarbonate-buffered mucus

Explain the movement through the large intestine

sluggish and weak, except for mass peristalic movements, which pass over the colon a few times a day to force the feces powerfully toward the rectum

Longest part of alimentary canal

small intestine

Most nutrients are absorbed in the

small intestine

What finishes chemical digestion?

small intestine

Site of most enzymatic digestion and all absorption of nutrients

small intestine (most absorption occurs in the proximal region)

Peyer's patches structure and function

small masses of lymphatic tissue found throughout the ileum region of the small intestine. Also known as aggregated lymphoid nodules, they form an important part of the immune system by monitoring intestinal bacteria populations and preventing the growth of pathogenic bacteria in the intestines.

In the walls of the sinusoids are __________________.

stellate macrophages - cleanse the blood of microorganisms and destroy worn out blood cells (like macrophages of spleen and bone marrow)

The two factors that play an important part in the movement of chyme from the stomach to the small intestine are:

stomach distension and gastrin release

The celiac trunk supplies arterial blood to what digestive organs?

stomach, liver,

Parietal cell location and function

stomach, secretes HCL and gastric intrinsic factor (b12 absorption) Parents on acid tried to gas their 12 year old son, didnt work so tried to use hcl to kill him.

enteroendocrine cell funtion and location

stomach, secretes gastrin, which stimulates secretion by parietal cells small intestine, secretes secretin or cholecystokinin (CCK), which stimulates release of bile and pancreatic juice and inhibits stomach secretions (small intestine) "entero" means small intestine "endocrine" means hormones (secretin)

Mucous neck cell location and function

stomach, secretes mucus

Chief cell location and function

stomach, secretes pepsinogen; beings proteins digestion

The esophagus's abdominal part, which is only about 2cm long, joins the ______________ at the ______________, where the _____________ acts to close off the lumen and prevent regurgitation of acidic juices into the esophagus

stomach; cardial orifice; cardiac sphincter

What layer of the alimentary canal contains major blood vessels, lymphatic vessels and nerve fibers?

submucosa

Which of the following major layers of the digestive tract is described as a layer of dense irregular connective tissue filled with blood vessels and the plexus of Meissner?

submucosa

What helps the bolus to pass through the esophagus?

submucosa of the esophagus wall contains mucous glands (tubuloalveolar glands)

Duodenum divisions

superior 1st descending 2nd transverse 3rd ascending 4th

Juntion of the pharynx and the esophagus

superior esophageal sphincter

The stomach is innervated by

sympathetic fibers from the splanchnic nerve and by parasympathetic fibers that derive from the vagus

Over most of its length, the large intestine exhibits three special features

teniae coli, haustra and epiploic appendages

What secretes saliva, bile and digestive enzymes which contribute to the breakdown of foodstuffs?

the accessory organs

In some places along the alimentary canal, sphincters prevent the backflow of food from one organ to the next, what are these sphincters made of?

the circular layer of the muscularis externa thickens

Intrinsic glands

the ducts and secretory cells of the various digestive lands, most of which lie fully within the wall

Largest gland in the body

the liver

A sphincter in the distal ileum keeps the valve closed until _________________, leading the cecum to fill

the stomach fills

What is different about the secondarily retroperitoneal organs layers?

they have both a serosa and an adventitia (serosa on the anterior side facing the peritoneal cavity)

Sympathetic input in the pancreas derives from the _____________ nerves whereas parasympathetic inpus is from the

thoracic splanchnic; vagus

Where is the alimentary canal does propulsion occur?

throughout the alimentary canal, from the oral cavity to the anus.

Mesentary of the large intestine that is fused to the underside of the greater omentum

transverse mesocolon

Esophagus muscularis externa consists of what type of muscle

upper 3rd: skeletal mid: skeletal and smooth bottom 3rd: smooth

Serosa is synonymous with

visceral peritoneum

Substances absorbed through the stomach

water, electrolytes and aspirin and alcohol.

The nutrients that can be absorbed without preliminary processing but may involve special transport mechanisms are:

water, electrolytes and vitamins

Digestive System begins forming into its adult shape when?

week 4

What is a hiatal hernea?

when walls of the diaphragm is weakend What happens with a hiatal hernea? the esophagus expands and the stomach introverts into esophagus

Does the digestive system continue to develop after birth?

yes

where esophageal epithelia changes to gastric epithelia

z line