Unit 14 - Ch23 Digestive System

Define the following (where in the digestive system does each occur): Absorption

- The process of nutrients being absorbed for use by the body. - Most absorption takes place in the small intestine. - Water is absorbed by the Colon. [Alimentary System]

What does the Lesser Omentum attach to?

- lesser curvature of the stomach; - anterior side - small modified mesentery contain adipose tissue fat keep organs warm

What is the function of the gallbladder?

- stores and concentrates bile - expels bile into duodenum • The bile enters the first segment of the small intestine aka duodenum • The gallbladder is releasing bile into the duodenum thru many tubes -> first tube is called cystic duct -> L/R hepatic ducts (pancreas) -> common hepatic duct • Cystic duct and common hepatic duct come together to form -> common bile duct

True or False: Majority of water absorption occurs in the small intestine.

False

Discuss the gross and miscroscopic anatomy of the esophagus

Gross = muscular tube > begins as a continuation of the pharynx > joins the stomach inferior to the diagram Microscopic > when empty mucosa and submucosa in longitudinal folds > mucous glands - primarily compound tubuloalveolar glands > muscularis externa - skeletal muscle first third of length > most external layer - adventitia

True or False: The pancreatic duct sometimes merges with the common bile duct.

True

What are the 4 components of the colon?

ascending, transverse, descending, sigmoid

Which of the following secretes HCl? a. Chief cells b. Parietal cells c. Follicular cells d. Parafollicular cells

b. Parietal cells

Define the following (where in the digestive system does each occur): Ingestion

begins at the oral cavity = where we bring food into the digestive system [Alimentary System]

Which of the following is NOT part of the alimentary canal? a. Mouth b. Pharynx c. Esophagus d. Tongue

d. Tongue

What is the function of Rugae of mucosa ?

folds in the stomach, purpose of these folds is to allow the stomach to expand • A difference bw the wall of the stomach and the rest of the layers of the alimentary canal is that the muscularis externa has 3 muscle layers (longitudinal, circular, oblique) > churning helps in mechanical digestion

What is the function of the liver?

function = is bile production and it's stored in gallbladder; bile is needed to help emulsify fats aka absorb fat within the small intestine > largest gland in the body > performs over 500 functions and many metabolic functions >has 4 lobes: left/right lobe, quadrate lobe and caudate lobe

Define defecation

large intestine, some absorption, material enters rectum -> feces -> expel material thru anus [Alimentary System]

Gross Anatomy of large intestine

material that enters the large intestine is coming from the small intestine thru ileocecal valve overview: material from ileum -> ileocecal valve -> cecum -> ascending colon -> transverse colon -> descending colon -> sigmoid colon -> rectum -> anal canal Teniae coil=smooth muscle Haustrum=pouches in the colon ,as a result of teniae coil contracts and created theses pouches allowing the material to flow from the cecum -> rectum Vermiform appendix=beg of cecum, contains lymphatic tissues, monitors what enters the large intestine and can potentially activate our immune, makes a lot of bacteria that helps protect the large intestine

The alimentary canal wall is composed of 3 layers:

mucosa, submucosa, and muscularis external. All 3 layers are pretty much the same throughout the entire alimentary canal.Major differences from one organ to the next is within the epithelium that lines the lumen

what kind of tissue is the stomach and small intestine?

simple columnar epithelium

Where is the Greater Omentum found?

they are a type of mesentery but instead of having blood vessels and nerves, they instead contain a bunch of fat located anterior side below the stomach

How are the omentums related to mesenteries?

they are a type of mesentery but instead of having blood vessels and nerves, they instead contain a bunch of fat > modified mesentery

The function of the esophagus, type of muscle movements occurring here, what is the epithelial type.

a tube that is composed of stratified squamous epithelium and it protects it (chew food 32 times) When the food moves from the oral cavity -> esophagus -> stomach the food doesn't just drop with gravity....peristalsis kicks in which contracts and pushes the food downwards.

Define the following (where in the digestive system does each occur): Chemical processing

It begins in the oral cavity when the salivary glands secrete saliva that begins the process of breaking down starches. Chemical digestion occurs in both the stomach and small intestines at the duodenum with the secretion of HCl and liver, pancreatic juices. (chemical enzymes) [Alimentary System and Accessory Digestive Organs]

The Pancreas

- pancreatic duct penetrates duodenal wall - endocrine functions = insule & glucagon - divided into 3. components: head, body, tail - organ that has dual functionally that participates in digestive and endocrine system > in endocrine it aids in region blood sugar levels thru the release of insulin & glucagon > in digestive acinar cells make/release

How does saliva assist in digestion?

The saliva glands secrete enzyme [chemicals] that begin the process of breaking down starches. > The saliva has an enzyme AMYLASE. This enzyme amylase helps to digest larger carbohydrates to smaller forms.

Name the 3 glands in salivary glands, function?

The salivary glands are w/in the oral cavity. Parotid gland= the largest gland, located anterior to either ear Sublingual gland = inferior side of the tongue Submandibular gland = bottom of mandible Function of glands = is to release saliva (chemically digestive)

Define the following (where in the digestive system does each occur): Propulsion

-the main way in which material is moved from the oral cavity and towards the anus is referred to as peristalsis > how? muscles contract and push food - swallowing food, pushing food from oral cavity to anus [Alimentary System]

Describe tooth structure.

1- the root of the tooth: located below the gumline in a bony socket 2- Neck 3- crown: projects above the gum line and is covered with enamel (calcium & phosphate) they are held in place by periodontal ligaments, connecting the tooth to the bone

Define the following (where in the digestive system does each occur): Mechanical processing

The teeth break down food by mashing, cutting and ripping the ingested food. The stomach churns food and food moves through the small intestine. [Alimentary System]

Describe the anatomy of a typical tooth; how many teeth are found in children vs adults, what are the differences?

Teeth are classified as incisors (front, help us cut thru food), canines (vamp/side, tear food), premolars, and molars. > Each tooth has an enamel- covered crown and a cement-covered root. > The bulk of the tooth is dentin (dentine), which surrounds the central pulp cavity. Deciduous teeth - 20 teeth = baby First, appear at 6 months of age Permanent teeth = 32 teeth or 28 (wisdom teeth pull out) = adult Most erupt by the end of adolescence

Describe the histology of the stomach. What do the chief and parietal cells secrete? What is the purpose of HCl?

The J-shaped stomach churns food into chyme and secretes HCl and pepsin, which begins the breakdown of food proteins. Lying in the superior left part of the abdomen, its major regions are the cardiac, fundus (superior), body, pyloric (inferior) part, and pylorus (containing the pyloric sphincter). Its right and left borders are the lesser and greater curvatures. When the stomach is empty, its internal surface exhibits rugae.

What is the function of the tongue?

- interlacing fascicles of skeletal muscles - grips food and repositions it - helps form some consonants - intrinsic muscles - within the tongue - extrinsic muscles - external to the tongue

What are the functions of the stomach?

- is a temporary storage tank in which food is churned and turned into a paste called chyme - breakdown of food proteins by secreting pepsin, a protein-digesting enzyme that can function only under acidic conditions, and hydrochloric acid, a strong acid that destroys many harmful bacteria in the food - Substances are absorbed through the stomach, including water, electrolytes, and some drugs (aspirin and alcohol) - Food remains in the stomach for roughly 4 hours

What are mesenteries, where are they found, what is their function?

2 visceral layers coming together that act like a sandwich and inside there's blood vessels nerves; they attached to posterior adbominal wall (visceral layer of the peritoneum) Found: most are dorsally located extending from the alimentary canal to the posterior abdominal wall and in the superior abdomen, a ventral mesentery extends ventrally from the stomach and liver to the anterior abdominal wall. > to keep blood vessels nerves all organized and protected within the abdominal cavity Function: hold organs in place, are sites of fat storage and provide a route by which circulatory vessels and nerves reach the organs in the peritoneal cavity.

What are circular folds, villi and microvill in the small intestine?

3 ways the small intestines can absorb/ secrete 1- circular folds = inside of the lumen; lining of the small intestine consists of a series of permanent spiral or circular folds, which amplify the organ's surface area, promoting efficient nutrient absorption 2- villi = contains simple columnar epithelium > within we see capillaries (absorb material except fat) and lacteal, absorbs fats -> delivered to our blood vessels > intestinal cavity, greatly increasing the surface area for food absorption and adding digestive secretions. 3- microvilli = on top of villi; increase the surface area for diffusion and minimize any increase in volume, and are involved in a wide variety of functions, including absorption, secretion.

What kinds of digestion occur in the mouth?

Both mechanical digestions performed by the tongue and teeth and chemical digestion performed by the saliva. > Mechanical digestion in the oral cavity consists of grinding of food into smaller pieces by the teeth, a process called mastication

Be able to identify and know the structures of the following items: Cecum, ascending colon, descending colon, transverse colon, sigmoid colon, hepatic flexure, splenic flexure, tenia coli, haustrum, vermiform appendix, rectum anus.

Cecum - lies in the right iliac fossa and contains the ileocecal valve. Attached to the cecum is the appendix, which contains abundant lymphoid tissue. a blind pouch. transverse colon- extends intra-peritoneal to the left across the peritoneal cavity. sigmoid colon- enters the pelvis and joins the rectum. hepatic flexure- is the sharp bend between the ascending colon and the transverse colon. The hepatic flexure lies in the right upper quadrant of the human abdomen. splenic flexure-e sharp bend between your transverse colon and descending colon in your upper abdomen. It's situated next to your spleen. Haustrum- are saccules in the colon that give it its segmented appearance. vermiform appendix- contains lymphoid tissue, neutralizes pathogens rectum anus. -The rectum is a chamber that begins at the end of the large intestine, immediately following the sigmoid colon, and ends at the anus

What are the four enzymes secreted by the pancreas, what are their functions, and what cells secrete the enzymes.

Exocrine functions - acinar cells make, store and secrete pancreatic enzymes Juice secreted into the small intestine - carbs = breaks down carbs - lipases = breaks down fats - nucleases = breaks down nucleic acid - proteolytic enzymes = breaks down proteins

True or False: The liver is the smallest gland in the body.

False:

Name the 3 tongue papillae and functions.

Filiform papillae = help material from sliding out of the mouth Fungiform papillae = tastes buds Vallate Papillae = tastes buds

Describe the following (know the function of each): Lingual frenulum Labial frenulum Oral cavity Hard and soft palate Uvula

Lingual frenulum = support the tongue and aid in limiting its movement in different directions; a fold of mucous membrane found underneath the tongue Labial frenulum = provide stability of the upper and lower lip and the tongue. Oral cavity = is to begin the digestive process thru mechanical & chemical digestion Hard and soft palate = form the roof of the mouth. >The soft palate is at the back of the roof, and the hard palate is the bony part of the roof closer to the teeth. The main functions of the soft palate are to aid speech, swallowing, and breathing. > The hard palate provides space for the tongue to move freely and supplies a rigid floor to the nasal cavity so that pressures within the mouth do not close off the nasal passage. Uvula = help to keep foods and liquid from entering the nasal cavity

What is the function of peristaltic movements, as well as segmentation? What areas of the alimentary canal do they occur.

PERISTALTIC - Adjacent segments of the alimentary canal relax and contract. Esophagus, Stomach and intestines. SEGMENTATION - Mixes food with digestive juices. Rhythmic local contractions of the intestine. It doesn't propel the food. Stomach and small intestine. main purpose=food is mixed and slowly propelled

What is the function of the pancreatic duct, and how is it associated with the common bile duct?

Pancreatic duct = tube inside the pancreas When food enters the stomach, these pancreatic juices are released into a system of ducts that culminate in the main pancreatic duct. The pancreatic duct joins the common bile duct to form the ampulla of Vater which is located at the first portion of the small intestine, called the duodenum.

Why are anal columns and anal sinus (depressions) important?

So at the end of the large intestine we have the anal canal. > Within the anal canal we have anal columns and anal sinus (depressions) • these are both important bc when we fart this prevents fecal matter 💩 from exciting out the anus

What is the anatomy of the mouth

The labia frenulum - connect lips to gym The palate - forms the roof of the mouth

a) What are the primary functions of the small intestine? b) Describe the structure of the wall of the small intestine. c) How is the surface area increased?

The material that exits the stomach now enters the small intestine and material is known as chyme a) Site of most enzymatic digestion and absorption b) The mucosa of the small intestine includes circular folds, villi, and microvilli c) Cells increase their surface area to optimize themselves for absorption and secretion aka microvilli. How? we add more membrane to the surface of the cell so we are increasing the contact of the cell and the environment

The Mouth and Associated Organs

The mouth—oral cavity • Mucosal layer > Stratified squamous epithelium = food enters the oral cavity, the food is rough so as we chew our mouth lining is protected by this > Lamina propria The lips and cheeks • Formed from orbicularis oris and buccinator muscles, respectively > lips are nonkeratinized

How does the wall for the large intestine differ from the small intestine?

The mucosa of the small intestine includes circular folds, villi, and microvilli. The wall of the large intestine - villi are ABSENT - contains numerous goblet cells - intestinal crypts: simple tubular glands - line with simple columnar epithelial tissue - epithelium changes at anal canal -> becomes stratified squamous epithelium

a) What are the primary functions of the large intestine? b) What kind of muscle movement occurs here?

a) absorb water and electrolytes (largely NaCl), and vitamins produced by bacteria Digestion: Some remaining food residues are digested by enteric bacteria (which produce vitamin K and B vitamins). Propulsion: Propels feces toward rectum by haustral churning and mass movements. b) Mass peristaltic movements force feces toward the rectum

Define peritoneal cavity and peritoneum

peritoneal cavity - a slit-like potential space peritoneum - a serous membrane > visceral peritoneum = surrounds digestive organs (deep) > parietal peritoneum = lines the body wall (outside) > organs within the abdominal cavity kidneys (retroperitoneal) are not protected by the serous membrane, bc there are behind the peritoneum

True or False: Anal columns prevent sharding during flatulence.

True

True or False: Both physical AND chemical digestion occur in both the mouth and stomach.

True

True or False: Segmentation also propels food down the alimentary canal.

True

Describe the general histological organization of the digestive tract: a. Mucosa b. Submucosa c. Muscularis Externa d. Serosa (found in. the abdominal cavity)

a. Mucosa - deepest layer, innermost layer which is connected to the Lumen and is composed of: -Epithelium: contains goblet cells that secrete mucous; lining the lumen -Lamina Propria: contains connective tissue & glands -Muscularis Mucosae: smooth muscle layer -Lacteal: a lymphatic vessel b. Submucosa- external to Mucosa layer a layer of connective tissue containing major blood and lymphatic vessels and nerve fibers, branching to all other layers of the wall. Composed of: intermediate between loose areolar and dense irregular; glands ad blood vessels c. Muscularis Externa- external to Submucosa Consists of 2 layers: Circular Layer & Longitudinal Layer(superficial) -Smooth Muscle -Inner Circular Layer: whose fibres orient along the length of the canal. d. Serosa - the outermost layer Consists of 2 layers: -Simple Squamous Epithelium (mesothelium) -Areolar connective tissue

Describe the two divisions of the digestive system: alimentary canal (muscular digestive tract) and accessory structures/organs.

alimentary canal = one long tube that begins at the mouth and ends at the anus. organs = mouth, pharynx, esophagus, and stomach, small & large intestine (colon), anus > is the same thing as G.I. tract accessory structures/organs = any organ that is part of the digestive system but is not part of the tube (alimentary canal). organs = teeth and tongue, gallbladder, salivary glands, liver, and pancreas

What is the function of bile? a. Breakdown of carbohydrates b. Emulsification of lipids (fats) & vitamins c. Emulsification of nucleic acids d. Breakdown of proteins

b. Emulsification of lipids (fats) & vitamins

What is the name for the primary means of propulsion down the alimentary canal? a. Segmentation b. Peristalsis

b. Peristalsis

In which of following does water absorption primarily take place? a. Stomach b. Small intestine c. Large intestine d. Pancreas

c. Large intestine

What is the purpose of cardiac sphincter?

circular muscle, contracts and closes of the entrance to the stomach, prevents anything from going back to the esophagus heartburn/acid reflux=when material form the stomach goes up to the esophagus, problem? HCL = burning sensation

What are the names of the ducts that transport bile from the liver and gallbladder into the duodenum?

common bile duct

In order for the digestive system to accomplish its task, it needs to go through its.....

digestive processes

What is the function of chief and parietal cells?

gastric pits --> gastric glands in the stomach, within the gastric glands we have chief cells and parietal cell; they both further aid in the breakdown of the material thru the process of chemical digestion and mechanical digestion chief cells = make and release enzyme pepsinogen (inactive form that further breaks down protein and HCL activates it) > when activated by HCL pepsinogen becomes pepsin, in the active form pepsin breaks down protein and HCL continues chemical digestion with whatever parietal cells = make and release HCL

What is the function of pancreatic juice?

pancreatic juice -> goes into pancreatic duct -> duodenum (small intestine) juice is designed to continue the chemical digestion

What is digested in the duodenum? How do the liver/gallbladder and the pancreas aide in the digestion process in the duodenum? What does each of them secrete?

receives material from the stomach(acidic chyme), liver, pancreas, gallbladder; a lot of segmentation > Bruner glands release alkaline substance to neutralize the pH of the acidic chyme > receives digestive enzymes and bile > main pancreatic duct and common bile duct enter duodenum (sphincters control entry of bile and pancreatic juices) in order for the environment to not be too acidic, the stomach will typically empty into the duodenum, one tbsp at a time so it takes 3hrs to empty the contents of the stomach -> duodenum -> jejunum -> ileum @ ileum we have payers patches = lymphatic tissue that are monitoring the material for pathogen -> enter the large intestine

What are the two hormones secreted by the pancreas, and what are their functions (which cells secrete the hormones).

secretes two major hormones: insulin (beta cells) and glucagon (alpha cells) which lower and raise blood sugar levels.Its exocrine function is to produce most of the enzymes that digest foodstuffs in the small intestine.

Define the following (where in the digestive system does each occur): Secretion

the chemicals released for chemical digestion happen in the Salivary glands of the oral cavity, glands in the stomach wall and the liver and pancreas, which release their chemicals into the small intestine. [Alimentary System and Accessory Digestive Organs]

The pharynx

the membrane-lined cavity behind the nose and mouth, connecting them to the esophagus We swallow the food -> oral cavity -> pharynx -> nasopharynx -> oropharynx -> laryngopharynx The function of oropharynx &laryngopharynx = passages for air and food > lined with stratified squamous epithelium > external muscle layer (superior, middle, inferior pharyngeal constrictors)

Define the following (where in the digestive system does each occur): Excretion

the process of eliminating food from the body. It occurs in the anus. [Alimentary System]