Digestive System Anatomy

Enzymes for Protein

Trypsin & Chymotrypsin Carboxypeptidase Elastase End product-> peptides and amino acids

Gallstones

When cholesterol crystallizes it forms gallstones. Gallstones can travel and lodge in the bile ducts.

Hepatocyte

Within hepatic lobules are liver cells called hepatocytes

Bile characteristics

Yellow-Green Color pH 7.6-8.6 Composed of cholesterol, bile salts, mucin, mineral salts, lecithin and bilirubin. No digestive enzymes An emulsifying agent

pylorus

a narrow, medially directed, funnel-shaped pouch that forms the terminal region of the stomach. Its opening into the duodenum of the small intestine is called the pyloric orifice. Surrounding this pyloric orifice is a thick ring of circular smooth muscle called the pyloric sphincter. T

Cardia

a small, narrow, superior entryway into the stomach lumen from the esophagus. The internal opening where the cardia meets the esophagus is called the cardiac orifice

Enzymes for Carbohydrate digestion

alpha dextrinase, maltose, sucrose, lactase -> End product: monosacharide

Proteins

amino acids -> active transport -> portal circulation

Pancreatic Juice

amylase; trypsin; chymotrypsin; lipase ; nucleases

Permanent Teeth

appear between 6 and 17 except for wisdom. 32; 4 types

Accessory Organs

assist in the digestion of food; teeth, tongue, salivary gland, liver, gallbladder, pancreas

Right Lobe

bigger lobe ; within it are the caudate(adjacent to inferior vena cava) and quadrate lobes (adjacent to gallbladder)

Bile ducts

bile travels through them from the liver to the gallbladder

Taste buds

bitter, salty, sweet, unami, sour

Mechanical digestion of the stomach

bolus is converted into soupy chyme

Stomach

bolus is mixed with gastric secretions including HCL, digestive enzymes, and mucin

Digestive system

break down ingested nutrients and absorb them

Digestion

breakdown of ingested food into smaller structures that may be absorbed from GI tract (mechanical and chemical)

Pancreatic amylase

carbohydrate digestion -> end product disacharide

Hepatic portal vein

carries blood from the capillary beds of the GI tract, spleen, and pancreas. It brings approximately 75% of the blood volume to the liver. This blood is rich in nutrients and other absorbed substances but relatively poor in oxygen.

Jaundice

ccurs when the liver's ability to eliminate bilirubin is impaired.

Parts of the large intestine

cecum, ascending colon, hepatic flexure, transverse colon, splenic flexure, descending colon, sigmoid colon, rectum (5-6 inches past sigmoid) Anal canal 1.5 inch at distal end of rectum and anus

Lips and Cheeks

cheeks contain buccinator muscles with help with chewing; lips are orbicularis iris muscles reddish hue because of abundant blood vessels

Bile is composed of .....

cholesterol, bile salts, mucin, water, mineral salts, lecithin, bilirubin.

Muscularis

circular (inner) and longitudinal( outer) smooth muscle layers, ; skeletal muscle in parts of tract under voluntary control; myerteric plexus (nerves) to control movement; Stomach has three layers of smooth muscle

Muscularis mucoase

circular and longitudinal smooth muscle ; contractions of smooth layover create movements of mucosa ; 1. release of secretions 2. increase contact of materials in the lumen with the mucosa

Alkaline mucous

coats the lining of the stomach

Esophagus anatomy

collapsed tubular passageway ; 10 inch; secretes mucous; guarded by sphincters ; gravity and peristalsis move the bolus along (4-8 seconds)

Brush boarder enzymes

complete chemical digestion of most nutrients immediately before absorption ; digest carbohydrates, proteins, and nucleotides

Intraperitoneal organs

completely surrounded by visceral; stomach, most of small intestine, part of large

Portal triad

composed of a hepatic duct bile ductule, and branches of the hepatic portal vein and the hepatic artery.

Function of the Gallbladder

concentrates and stores bile

Adventita or Serosa

connective epithelial layer; serosa (visceral peritoneum) covers organs in abdominal cavity ; adventita covers the esophagus

Lesser omentum

connects the superiomedial surface (lesser curve) and the proximal end of the duodenum to the liver (attaches liver to lesser curvature)

Bulimia

consumption of large amounts of food followed by self-induced vomitting or purging of the intestine with laxatives

Tongue

contains taste receptors; skeletal muscle; extrinsic and intrinsic muscles;

Visceral peritoneum

covers the surface of internal organs

Molars

crushing and grinding (12) -not in deciduous

first set of teeth

decidous or milk teeth ; begin at 6 months, are lost between 6 and 13, are 20

Ascites

develops because of decreased albumin production.

Constipation

difficult or infrequent defecation ;including a diet low in fiber (insufficient bulk), dehydration, lack of exercise, and improper bowel habits (not defecating when the urge arises, allowing additional water to be absorbed from the feces). Constipation is also a common side effect of general anesthesia.

Retroperitoneal organs

directly against the posterior abdominal wall, only anteriolateral portions are covered with peritoneum. Most of the duodenum, pancreas, ascending and descending colon, rectum

Ileum

distal 10 ft. attatches to cecum ; intraperitoneal

Mesentery

double layer of peritoneum that supports, suspends, and stabilizes, the intraperitoneal GI tract organs; blood vessels, nerves, and lymph vessels are sandwiched between two folds that supply the digestive organs

Peritoneum

double-layered membrane containing blood vessels, lymph nodes, nerves and fat

Small intestine

duodenum, jejunum, ileum. 10 foot tube for digestion and absorption ; 12 hours, finishes chemical digestion; pylorus to cecum

Mass Peristalsis

e powerful, peristaltic-like contractions involving the teniae coli, which propel fecal material toward the rectum. A wave of contraction begins in the middle of the transverse colon, forcing a large amount of fecal matter into the descending colon, sigmoid colon, and the rectum.

Salivation changes

exercise or when excited/anxious (sympathetic) results in more vicous saliva by decreasing water content. contracts capillaries decreases fluid

Elimination

expulsion of indigested components that are not absorbed

Greater omentum

extends inferiorly like an apron from the inferiolateral surface of the stomach and covers the abdominal organs "fatty apron-adipost tissue"

Mesentery proper

fan shaped fold of the peritoneum that suspends most of the small intestine (jejunum and ileum) from the internal surface of the posterior abdominal wall

Liver Cirrhosis

fibrosis and nodular regeneration

Vili

fingerlike projections off the mucosa; increase surface area; most numerous in the jejunum ; contain lacteal and blood vessels

Mesocolon

fold that attaches part of the large intestine to the internal surface of the posterior abdominal wall (transverse, sigmoid, etc)

Incisors

for biting (8)

Monoscharides absorption

fructose -> facilitated diffusion -> portal circulation Glucose and Galactose -> active transport with NA+ -> portal circulation

Pharynx anatomy

funnel shaped passageway for both food and air; superior middle inferior muscles

Gastrin

g cells secrete it (hormone - stomach secretions and motility)

Rugae

gastric folds; seen only when the stomach is empty; allows the stomach to expand

GERD

gastroesophageal reflex disease; lower esophageal sphincter fails to close

Premolars or Bicuspids

grinding (8)

Gingiva

gums; dense irregular connective tissue, overlying nonkeretinized stratified squamous epithelium

Movements of the large intestine

haustral churning; peristalsis, mass peristalsis, defecation reflex

Bile caniculi

his is a small channel that conducts bile produced by hepatocytes to the hepatic duct in the portal triad

Peritoneal cavity

in between parietal and visceral; allows them to move freely and avoid friction

Diarrhea

increased frequency of defecation, the fluidity and volume of feces.disruption in normal mechanisms to absorb intestinal water, or excessive amounts of osmotically active solutes that keep water in the intestinal lumen and prevent its reabsorption.

Sublingual gland

inferior to the tongue; 3-5% of saliva ; serous and mucin

Mucosa

innermost layer; secretes mucous; composed of three layers (epithelium, lamina propia, muscular is mucosae) Glandular except in the anus

Haustra

intestinal pouches (sacs)

ingestion

intro of solid and liquid nutrients to mouth

Fungiform

large and round, contain taste buds (side of tongue)

Parotid Gland

largest; anterior and inferior to the ear; 25-30% of saliva ; only serous

Partietal peritoneum

lines the inside surface of the body wall

Substrates produces by salivary glands

lingual lipase(intrinsic) ; Serous cells produce salivary amylase which starts the chemical digestion of carbohydrate into disaccharide

Liver lobules

liver is made up of six-sided functional units

lamina propria

loose connective tissue (areolar) containing blood vessels, lymphoid tissue and glands

Oral Cavity and Salivary Glands

mechanical digestion, saliva is secreted in response to food->forms a wet mass called a bolus. Salivary amalyse (hydrolytic enzyme that initiates chemical digestion of starch)

Brush boarder

microvilli ; fuzzy edge of simple columnar ; enzymes are embedded within

Segmentation

mixes chyme with accessory gland secretions through "back and forward" motions More prevalent in the beginning ; Chopping action

Histology of the Pancreas

modified simple cuboidal epithelial cells called acinar cells that are arranged in saclike acini

Esophagus

mucus lubricates the passage of the bolus

Mucus

mucus neck cells

Gastric pits

numerous depressions into the stomach lining; contains many specialized cells

Haustral churning

occurs after a relaxed haustrum fills with digested or fecal material until its distension stimulates reflex contractions in the muscularis. These contractions increase churning and move the material to more distal haustra

Voluntary phase

occurs after ingestion; controlled by the cerebral cortex ; Ingested materials and saliva mix in the oral cavity ; Chewing forms a bolus mixed and manipulated by the tongue pushed against the hard palate; Transverse folds help push them back posteriorly

Cephalic phase

occurs before the food enters the stomach; Involves the cerebral cortex, hypothalamus and medulla; Presence of food elicits gastric secretion and motility; Simple stress increases gastric emptying; Chronic stress decreases (Vagus nerve stimulate G cells -> Gastrin -> gastric secretion and motility increase)

Peristalsis

of the large intestine are usually weak and sluggish, but otherwise they resemble those that occur in the wall of the small intestine.

Microvilli

off the vilus to further increase surface area of the plasma membrane allowing epithelial cell to absorb more quickly

GI tract organs

oral cavity, pharynx (throat), esophagus, stomach, small intestine, and large intestine, ends at the anus. (30 ft)

Upper GI

oral cavity, pharynx, esophagus, stomach, duodenum

Enzymes for Fat

pancreatic lipaseEnd-products - fatty acids and monoglycerides

Absorption

passive movements and active transport of digested molecules, electrolytes and vitamins and water from GI tract -> blood or lymph

Chief cells

pepsinogen and gastric lipase

HCL functions

pepsinogen into pepsin and regular Ph ; kills microorganisms ; break down of plant cell walls and animal tissues ; denatures proteins

Falciform ligament

peritoneal fold that attaches the liver to anterior abdominal wall ; separates the liver into right and left lobe

Saliva

ph: 6.35 -6.85 ; 1000-1500 mL/day; contains water, buffers, mucus, lysosome, amylase. Under ANS control and influenced by higher brain centers

Involuntary phase

pharyngeal and esophageal phase

Functions of the Digestive System

physical and chemical breakdown of food; absorption of nutrients; elimination of solid waste (ingestion, motility, secretion, digestion, absorption, elimination)

Mechanical digestion

physically broken down (chewing)

Detoxification

poisons; alcohol; nicotine; barbituates; removing hormones

Epiploic Appendages

pouches of fat hanging off external haustra

Submandiublar gland

produce most of the saliva 60-70% inferior to floor of the oral cavity ; serous and mucin

Salivary Glands

produce saliva which moistens and cleanses the mouth and begins the chemical breakdown of food (sublingual, submandibular, parotid)

Secretion

produces and releases fluid products such as digestive enzymes acids and biles into GI tract. The secretions facilitate digestion

Hiatal Hernia

protrusion of an organ through the diaphragm into the thorax.

Anorexia Nervosa

psychological and physiological syndrome characterized by bizarre eating habits, distorted body image, abuse of laxative and diuretics, very vigorous exercise, self-imposed starvation

Pharyngeal phase

reflex of swallowing by tactile receptors; 1 second between pharynx and esophagus

Hormonal Regulation

regulated by gastrin ; stimuli are distention of stomach, partially digested proteins, increase in pH, caffeine, and acetylcholine

Intestinal Phase

regulates flow of chyme from stomach into intestine; tends to slow exit from stomach; has inhibitory effect. Stimuli (fatty acids Amino acids Hypertonic fluids Irritants Distension) g cells - secretin ccl- Decrease secretion of gastric juice. Decrease stomach motility. Promote feeling of satiety. (stimuli - distention of duodenum ->enterogastric reflex of duodenum -> medulla -> decreased motility of the stomach )

CCK

relaxes the spinchter of Oddi

Bile from liver

released from gall bladder into the duodenum (alkaline)

ligamentum teres

represents the remnant of the fetal umbilical vein

Palate

roof of the oral cavity, barrier for nasal cavity. anterior 2/3 is hard palate , posterior 1/3 is soft and muscular (soft palate)

Acini

s produce and release hydrolytic enzymes. Small ducts lead from each acinus into larger ducts that empty into larger pancreatic ducts that lead to the duodenum (as described earlier). The simple cuboidal epithelial cells lining the pancreatic ducts have the important function of secreting alkaline HCO3− fluid.

Diverticulosis

sac like outputting of mucosal layer of the colon

Stomach anatomy

sac-like organ that receives the bolus of food from the esophagus

Lipids

short-chain fatty acids -> simple diffusion -> portal circulation Long-chain fatty acids + monoglycerides + bile salts -> micelles (water soluble microemulsion) Diffused micelle products reform into triglyceride drops Triglyceride droplets +protein coat -> chylomicron -> lacteal thoracic duct -> left subclavian vein

Large intestine

shorter than the small but diameter is greater;Water is drawn out of chyme, and feces are formed and stored in the large intestine. ; 5 feet long

epithelium

simple columnar, which allows for secretion and absorption. abrasion organs (esophagus) are nonkertinized stratified squamous

Chemical digestion

specific enzymes to break chemical bonds ro change large components to smaller ones

Neural Regulation

stimuli are distension of stomach and increase in pH by proteins; Nerve impulses case release of gastric juice and increased peristalsis

Function of the stomach

storage from 2-4 hours; turns bolus into chyme; activation of lingual lipase; digestion of proteins and some fats; limited absorption of water, alcohol, and some drugs

Neural Regulation of intestinal phase

stretch receptors of duodenum send impulses to medulla. Sympatheti nerves to stomach are stimulated. Gastric motility slows down

Taeniae coli

strips of muscle act as an elastic waste band to bunch up large intestine into many sacs

Metabolism

sugars are converted to glycogen ; glycogen is converted to sugar and heat, H20 and CO2; Fats and fatty acids and glycerol; amino acids are converted to ammonia and urea

Deglutition

swallowing - voluntary phase; involuntary phase

Pharynx

swallowing of bolus; mucus secreted in saliva and in superior part of esophagus to initiate swallowing

functions of the liver

synthesis; storage; metabolism; detoxification; RBC processing

Filiform

tall and narrow, contain touch receptors (front of tongue)

Canines or cuspids

tearing (4)

Edema

the accumulation of fluid in body tissues, is evident due to reduced formation and release of albumin

fundus

the dome-shaped region lateral and superior to the esophageal connection with the stomach. Its superior surface contacts the diaphragm.

Defecation

the elimination of undigested waste

body

the largest region of the stomach; it is inferior to the cardiac orifice and the fundus and extends to the pylorus.

Absorptive cells

transport nutrients from chyme to the blood vessels and lacteals.

Circuvallate

v-shaped, contain taste buds (back of tongue)

Muscularis of the stomach

varies from the general GI tract pattern in that it is composed of three smooth muscle layers instead of two: an inner oblique layer, a middle circular layer, and an outer longitudinal layer. The oblique layer is most developed at the cardia and the body of the stomach. The presence of a third layer of smooth muscle assists the continued churning and blending of the swallowed bolus to help mechanically digest the food. The muscularis becomes increasingly thicker as it progresses from the body to the pylorus.

Motility

voluntary and involuntary contractions to mix and move materials through GI tract

Gastric lipase

works with pepsin to break down fat

Islets of langerhans

α-cells produce glucagon β-cells produce insulin

Circular folds of small intestine

(plicae circulars) mucosal and submucosal layer ; extend inward toward the lumen ; help increase surface area for absorption; speed bumps to slow down chyme ; least in the ileum

What does defecation involve

1. an intrisic reflex initiated by the stretch of the rectum 2. a parasympathetic reflex involves the spinal cord (intestacies rectal peristalsis, relaxes internal and sphincters) Higher brain centers control external anal sphincters

Duodenum

10 inches long originates at pyloric sphincter (attaches to stomach)C shaped around head of the pancreas receives accessory gland secretions

Gallbladder

3-4 inch sac Lined with rugae Capacity 40-50 mL

GI tract layers

4 layers called tunics. Mucosa; submucosa; muscular is; serosa or adventita

Esophageal phase

5-8 seconds; presence of bolus in the lumen stimulates waves of muscular contraction to propel it down; Spincters relax to allow passage

Enzymes for protein digestion

Aminopeptidase Dipeptidase End-products - peptides and amino acids

Submucosa

Areolar connective tissue; contains Meissner plexus (neurons)- regulate movement, secretion, and blood vessel size; 2 layer of the digestive tract

Product of the Liver from Gall Bladder

Bile

Synthesis function

Bile salts from cholesterol ; phrothrombin and fibrinogen; albumin and globulins; glycogen

Hormonal Regulation of Intestinal phase

CCK from small intestine responds to amino acids, and fatty acids. Pancreas produce juice rich in digestive enzymes, causes contraction of gall bladder, slows gastric emptying ; Secretin from small responds to acids ; Pancreas produce bicarbonate rich juice, slows production of acids

Enzymes for nucleic acid digestion

Enzymes for Nucleic Acid Digestion Nucleosidase Phosphatase End-products - bases, pentoses, and phosphates

Pancreas

Enzymes of the pancreas pass through the pancreatic duct into the duodenum; Secret insulin and glycogen (endocrine cells) and pancreatic juices (exocrine cells) ; Retroperitoneal

Defecation reflex

Filling of the rectum initiates the urge to defecate. This stimulus results in transmission of nerve signals from the receptors to the spinal cord. In response, parasympathetic output increases to both the sigmoid colon and rectum, while it decreases to the internal (involuntary) anal sphincter.

Components of Digestive system

GI tract (upper and lower) and accessory organs

If bile drainage is blocked...

Gallstones may occur

Storage

Glycogen; fats; amino acids; vitamins; metals

Formation of HCL

H20 is broken down into h and oh; H is pumped through ; OH bonds with CO2 to make HCO3 ; HCO3 leaves parietal cell and CL enters ; CL combines with H in the gastric gland

Chemical digestion of the stomach

HCL inactivates salivary amylase ; Pepsin breaks down proteins into peptides ; HCL activates lingual lipase which breaks down fats into fatty acids and monoglycerides; Gastric lipase breaks fat into fatty acids and monoglycerides in babies

Parietal Cells

HCL(H+ and Cl- separately) and intrinsic factor (b12 which is needed for red blood cells)

Peptic ulcer

Helicobacter pylori NSAIDs like aspirin Excess production of pepsin

Bile Drainage

Hepatic Cells -> Left and Right Bile Ducts -> Common Hepatic Duct -> Joins with Cystic Duct-> Common Bile Duct-> Common Bile duct and pancreatic duct -> Ampulla of Vater -> Duodenum

Clinical Signs of a failing liver

Liver cirrhosis; jaundice; edema; ascites

Products of the Paneth Cells

Lysozyme

RBC processing

Makes fetal RBC; destroys RBC; stores blood

Jejunum

Middle 7.5 ft. 2/5 of the small intestine; primary region for chemical digestion in the small intestine intraperitoneal

Gastric phase

Occurs when food enters the stomach ; distention of stomach by food and substances in food stimulate the gastric mucosa ; primary effect to speed up mechanical and chemical digestion (G cell- gastrin-Parietal cells release HCl. Gastric glands release gastric juice.) Neural Reg and Hormonal Reg

Enzymes the pancreas produces

Pancreatic amylase to digest starch Pancreatic lipase for the digestion of fats Inactive proteases (trypsinogen, chymotrypsinogen, and procarboxypeptidase) that, when activated, digest protein Nucleases for the digestion of nucleic acids (DNA and RNA)

Perstalisis

Peristalsis then propels material within the GI lumen by alternating contraction of the circular and longitudinal muscle layers in small regions. The rhythm of muscular contractions is more frequent in the duodenum than the ileum, thus the net movement of intestinal contents is toward the large intestine ; Forward movement

Secretin influence

Release of pancreatic juice rich in bicarbonate Release of alkaline rich-bile from the gallbladder

CCK influence

Release of pancreatic juice rich in enzymes. Release of bile from gallbladder Release of pancreatic juice and bile into the duodenum

Enzymes for nucleases

Ribonuclease Deoxyribonuclease End-products - nucleotides

Functions of the large intestine

Secretes mucus, absorbs water, absorbs NA and K synthesizes vitamin b and k ; completes digestion through bacterial activity (ferment sugars, putrefaction of protein residues (phenol, indol, skatol); stores feces

Products of the Endocrine Cells

Secretin Cholecystokinin (CCK)

Internal nerve plexes

Stomach stretch and rise in pH also stimulate the internal nerve plexes which increase stomach motility.

Role of Bacteria in large intestine

Synthesize vitamins B and K Ferment carbohydrates and sugars Putrefy proteins and amino acids into phenols, indoles, and skatoles Decompose bilirubin

Liver

The liver is the largest internal organ, weighing albs, and it constitutes approximately 2% of an adult's body weight. The liver is covered by a connective tissue capsule and a layer of visceral peritoneum