Ch 24 Flashcards
How does pH change through GI tract?
Mouth neutral
Mumps
parotoid salivary gland infected with the mump virus
- Can attack one side OR both
- Characterized by extreme swelling, fever, throat pain, and malaise (low energy)
- More severe in males in fertility years, can descend to testicles causing infertility (usually just to one testicle)
Salivation process controlled by
ANS
Two components of digestive system
GI tract
Acesssory organs
6 basic processes of digestion
Ingestion
Secretion
mixing and propulsion
Digestion (Mechanical and chemical)
Absorption
Defactation
Secretion in GI tract
All the enzymes and acids released to chemically digest food
Absorption
The nutrition in the food that we’ve broke down is going from the GI tract into either blood or lymphatic fluid.
- Only thing that goes from small intestine into lymph fluid are long chain proteins.
- Abt 95% of absorption from small intestine.
Most absorption occurs where
Small instesine (95%)
Defecation
residual tissue or breakdown products that can’t be absorbed
Urination: Fluid elimination
- Fiber that can’t be absorbed
The layers of the GI tract
Mucosa
Submucosa
Muscularis
Serosa
Same 4 thorughout, but structure varies
Mucosa layer
Epithelium
For absorption will be simple cuboidal
Regenerative ability of cuboidal tissue 5-8 days
b) Lamina Propria means connective tissue
Everytime there’s an epitheleal layer there’s also a
Connective tissue layer
MALT
(Mucosa Associated Lymphatic Tissue): Clusters of lymphatic nodules (Not nodes) part of the immunity protection system.
- Name came from the fact that nodules located in mucosa tissue
Located in the lamina propria of mucosa layer
Muscularis mucosae
(smooth muscle)
- Produce ridges or folds which help with propulsion and surface area
part of mucosa layer
Submucosa
Where the nutrients have to travel to be absorbed if in the small intestine
- Lot of blood and lymphatic vessels
Muscularis
Typically a circular AND longitudinal layer (In stomach there’s a third layer called the oblique
Includes Voluntary function of skeletal muscle when swallowing
What is the extra layer of musclarais that exists in only one location (where)?
Oblique layer in the stomach
Serosa layer
Outer layer, on top of organs in the abdominopelvic cavity
- Areolar connective tissue
- Simple squamous
How do 4 layers of GI Tract change from mouth to anus
2 main networks of the ENS
- Myenteric plexus
Submucosal plexus
Myenteric plexus
Helps primarily with motility = mixing and pushing food forward (Bw circular and longitudinal layer)
Submucosal plexus
Predominantly involved in secretion
Why would someone get stomach ache on first day of school?
Sympathetic system dominating more than parasymp
Largest serous membrane in the body
Peritoneum
1.) Parietal Peritoneum
Membrane portion that lines the abdominal cavity (epithelial tissue)
Peritoneal cavity
Bw parietal peritoneum and visceral peritoneum
Small amount of fluid
Excess fluid in peritoneal cavity
Interferes with digestion and be site for infection
2.) Visceral Peritoneum
Membrane covering the organs
5 Peritoneal folds
Greater Omentum
2) Falciform Ligament
3) Lesser Omentum
4) Mesentery
5) Mesocolon
- Peritonitis
- Acute inflammation, taking up residence, fluid is excessive
- Vestibule
Entrance to mouth
Hard pallate
Anterior Roof of the mouth – it is bone
- Separates oral cavity (mouth) from nasal cavity
Soft pallate
Posterior roof of mouth
lined with mucous, typically muscle
Last site that the skull fuses
Midline in the mouth
What is a cleft palate
Improper fusion of the hard palate midline
Uvula purpose
- Supposed cover nasal pharynx during time when person is swallowing
- Doesn’t work when talking and eating well
What is the begining of chemical digestion
Saliva
What is saliva
99% water
Antibodies and enzymes
Breaks down carbs and starch
Ideal pH for mouth
6.35-6.85
Parotid glands
Beside ear
Sublingual glands
Under tongue
Submandibular glands
Under mandible
What type of glands are the salivary glands
Exocrine
Purpose of intrinsic muscles in tongue
Help change shape
Papillae
Elevations on tongue, taste buds
Some have tactile purpose
Lingual glands
producing lipase (enzyme_) that works on fats
Lingual lipase
Enzyme digesting fat (Lipids) not activated until the stomach
Enamel of teeth
top surface
Good dental health linked to
Cognitive functions
Gingivae
Gums
3 parts of tooth
Crown, root, neck
Pulp and dentin
Location of blood and lymp vessels and nerves
Deciduous teeth
Appear from 6 months to 12 yrs
Mastication
Chewing
Taste is improved with
More chewing
Bolus
Broken down food mixed with saliva
Salivary amalayse
most important in mouth, helps break down carbs and starch
- Without enough chewing and mixing this doesn’t happen
Deglutition
Swallowing
3 phases of swallowing
From mouth to oropharynx - Voluntary (1)
From oropharynx to esophagus - involuntary (2)
From esophagus to stomach - involuntary (3)
- Upper Esophageal Sphincter
(Circular muscle): Regulates bolus from throat into esophagus.
Muscle in swallowing that older adults can lose use of
- Esophageal Stage and Peristalsis
- Lower esophageal Sphincter
Controls bolus from esophagus into the stomach
Heart burn is a problem with
lower esophageal sphincter
pH in stomach
2
When stomach burns itself it is called an
ulcer
What protects stomach from the acid
mucous layer
What decreases ability for lower esophageal sphincter to close
- Smokers, coffee drinkers, and chocolate can cause decrease in the ability for lower sphincters to close and thus heart burn
Anatomy of stomach
Cardia
Fundus
body
Pylorus
Pyloric Antrum
Pyloric canal
Pyloric Sphincter
Cardia of stomach
Where esophagus joins stomach (threshold)
Fundus of stomach
first part of stomach AFTER the cardia
Pylorus
(anything CLOSE to the small instestine)
- Wants smaller doses of food going into small intestines at once
Pyloric antrum
trainglular area CLOSE to the small intestine
Pyrloric sphincter
Circular muscle controlling release of food from the stomach into the duedidum
Pyloric spasm
When pyloric sphincter is TOO tight, does not relax sufficiently, infant is breast feeding but stomach becomes distended bc milk cant leave the stomach – eventually reflexively impacts vomiting
Pyloric stenosis
Disabiltiy involving pyloric Narrowing, food has difficulaty leaving the stomach, SOME can leave, but person always have distended stomach (surgery or drugs)
Rugae
Folds on internal surface of the stomach
- only visibly in epty stomach, allowing for stretch
Gastric pit/gastric glands
Glands (Three kinds of exocrine gland cells in the gastric glands) : Tunnels ptis or holes on surface of the stomach, locatd on the walls of the pits, various type sof cels that secrete different elements
3 types of surace mucous cells
Layer 1
Mucous neck cells
Chief cells
Parietal cells
All exocrine glands
Mucous neck cells
- There are surface mucous cells that secrete mucous (1-3 mm thick to protect stomach from acid
- Also mucous secreting cells on the neck
Chief Cells
- Secrete chemical called pepsinogen (inactive enzyme)
- Acitivates when it hits low pH
- Pepsinogen works on proteins
Parietal cells
- Produce HCl, lowers the pH to 1-2
- Help denature proteins (break peptide bonds)
- Some bacteria cannot survive that
Extrinsic factors of surface mucous cells eventually help to
Absorb vitamin B
- Enteroendocrine Cell (G cell
Produces hormone, goes into blood and comes back to affect the stomach
Gastrin
Produced by G cells, function to activate muscles and relax the sphicnter allowing food to leave the stomach
Chime
Food mixed with gastric secretions
Gastric juice =
All secretions
Volume of gastric juice secretions per day
2000-3000mL
Stomach ulcers indicate
Mucous layer is too thin
Submucosa layer of stomach
2nd layer
Primarily areolar connective tissue
- Laminar propia: Connective tissue
Muscularis layer of stomach
- Having circular, longitudinal, AND oblique muscle
Serosa
- Simple squamous membrane layer on top (Most outer layer)
Mixing waves
Food is chruned around in the stomach begining several minutes after it has entered
Peristalic waves
Food is pushed forward into pyloric region
Gastric emptying
some amount of chyme is leaving the stomach and entering the small intestine
What is organ is the “gastric” associated with
Stomach
salivary amalyse
produced in the mouth
- once it hits low pH of the stomach it becomes inactive (Cannot function in acidic environment)
COnverts starch into sugar
Funnction of HCl
Denatures protein
Kills bacteria
Lingual lipase
Produced in the mouth, becomes active once it hits the stomach, works on fats (triglycerides)
Pepsin
Active form of pepsinogen, activates when pH is low
Gastric Lipase
: Another enzyme working on triglycerides but it is produced in the stomach
- Quite limited in adults, more prevalent in breast feeding infants, mainly works on milk fat
Pancreas function in digestion
Both an exocrine AND endocrine function
COnsidere accessory organ because it ads secretion to the small intestine
- Joins right up to small intestine right under ther small intestine
Key ducts of pancreas
Pancreatic duct
Side tract
Common Bile duct
Carrying secretions from galbladder, combines with side tract from pancreas and join into the hepato ampulla
Hepatopancreatic ampulla
- Where the secretions from the bile and pancreas join together and enter the dedendum
Accessory duct
Leads from the pancreas and empties into the duodenum
99% of cells in pancreas
Acini cells = exocrine (secretion through tube into another location)
1% of pancreatic cells
Pancreatic islets = endocrine (Secretion goes into blood, travels through body, then comes back to small intestine)
A cells in pancreas
(produce a hormone) glucagons (increase blood glucose)
B cells in pancreas
→ (produce) insulin (Decrease blood glucose by pushing it into cells)
- Generally just trying to work to stabilize blood glucose level
D cells in pancreas
somatostatin (Similar to human growth hormone, slows down release of both insulin AND glucogon)
- Also slows down absorbtion in the small intestine
- Net result = more time to finish up digestion
F cells in pancreas
(Hormon) pancreatic polypeptide
- Decrease exocrine pancreatic secretion
- Decreases bile release from the gallbladder
- More time for small intestine not to be overloaded by food and digestive enzymes
What would result in pancreatis (inflamation of pancreas)
Gallstones or alcohol abuse
Acute pancreatitis
Alcohol lonterm has damaged pancreas or some of the ducts in pancreas are blocked so digestive enzymes in pancreas cannot escape and a couple of them begin digesting pancreas
What cells make up pancreatic juice
Pancreatic amalayse
trypsin
chymotrypsin
carboxypeptidase
pancreatic lipases
ribonuclease
deoxyribonuclease
When do pancreatic enzymes become active
Once they reach the intestine (otherwise they would digest pancreas)
Neural regulation of pancreatic secretion
if parasympathetic function goes up, pancreatic secretions go up
- Sympathetic function goes up, pancreatic secretions decrease and thus digestion slows
How do SI hormones regulate pancreatic secretion
- Secretin: If secretin hormone goes up, pancreatic secretions go
up - CCK (cholecystokinin): When there is food or chime in the small intestine, CCK production goes up
- Secretions in the small intestine goes up
Two main lobes of liver seperated by
Falciform ligament
Fold of peritoneum extending from diaphragm to superior surface of liver = suspends liver
What would u have to be careful of if galbaldder is removed
Fatty foods since you can no longer store bile to break down excessive amounts of fat
Functional units of liver
Lobules
Hepatocyte
Liver cell
- The most common cell, perform the jobs of the liver
- Detoxify, produce the bile
- Major workers of each of the lobules
Bile canaliculi
- Collect the bile produced by the hepatocytes
- Bile is stored and concentrated in the galbladder
Hepatic sinusoids
Of liver
- Blood vessels
- stellate reticulocytes (Kupffer)
Stellate reticuloendothelial cell are phagocytic cell within hepatic sinusoids
Central vein/hepatic vein of liver
- Central part of each lobule
Portal Triad made up of
1 bile duct + 1 hepatic artery + 1 hepatic vein
How does bile move from liver to galbladder
Bile → bile canaliculi → bile ductules → bile ducts →Merge to form R and L hepatic ducts → Exit liver as common hepatic duct → Stored in gallbladder by way of cystic duct
Jaundice cause
- Due to pigment called bilirubin
- When RBC are recuycled, proteins go one way and pigment goes to be broken down in the liver
Two main suoures of liver blood supply into liver sinusoids
Hepatic Artery: Oxygen rich blood
Hepatic Vein: Oxygen poor blood
Role of bile
Emulsification of fats
operates best at pH 7.6-8.6
Functions of liver
Carb metabolism
Lipid metabolism
Protein metabolism
Drug and antiobiotic processing
Bilirubin excretion
Bile salt synthesis
Storage
Phagocytosis
Vit D activation
What is the carbohydrate metabolism
glycogenolysis + gluconeogenesis
Glycogenolysis: Breakdown of glycogen to produce glucose
- Gluconeogenesis: Production of glucose from non hydrolatic sources
Galstones caused by
Insufficient bile salts, excess cholesterol in gallbladder, produces crystals, form into gallstones.
Gallstone effects
- Pain and blockage of ducts, glabladder not able to empty bile
- Options: Drugs to interup stone formation, shockwave therapy (explode gallstones), surgery for serious occurances
Major role of SI
i) Digestion
ii) Absorption
Parts of SI
- Duodenum (2.5 cm) Beginning
- Jejunum (1m)
- Ileum (2m)] End
- Ileocecal sphincter
What is the hairy cilia border in the small intestine called
Brush border
3 types of cells making up intestinal glands and brush border
Goblet cells
Paneth Cells
Lacteal
Goblet cells
produce and secrete mucous
Paneth Cells
Secrete lysosomes (Which engage in phagocytosis)
What are enteroendocrine cells
Hormones
What hormones are secreted by cells along the brush border
S-cells (secretin)
CCK -cells (Cholecystokinin)
K-cells (Glucose-dependent insulinotropic peptide)
Lacteal
: In the middle of each villus, a lacteal is a part of the lymphatic system
- If very large fatty acid (tricglycerides), it travels through the lacteal
Villi
The collective villus fingers of the small intestine
Microvilli
Brushborder
Brunner’s glands (Duodenal), circular folds are part of what
Submucosa layer of small intestine
Brunner’s glands (Duodenal glands)
- Important, secretes alkaline secretion
- Important for neutralizing acidic environment coming from the stomach
of small intestine
- Circular folds (Plicae)
of small intestine
- Increase surface area for absorbtion secretion AND movement
How many layers of the muscularis are there in the SI
2
Serosa surrounds entire SI except
Small part of duedenum where it intersects with the stomach
How much intestinal juice secreted per day
1-2L
pH of intestinal juice
7.2-7.6
Segmentation in small intestine
- Localized mixing (with existing enzymes)
- Generally 12 times per minute
MMC
Migrating motility complex
- pushes the chime in SI forward after most absorption has taken place
Chemical digestion that occurs in mouth
CHOs (Carbs)
Chemical digestion that occurs in stomach
proteins/fats
Chemical digestion that occurs in SI
All (proteins, fats, and carbs)
Lactose intolerance
Cells lining villus and in brush border are lacking the enzyme lactase
What enzymes digest proteins
- Pepsin and Pancreatic Juice
- Peptidases
- Aminopeptidase
- Dipeptidase
What enzymes digest fats
- Lipases (Collectively called lipases)
- Lingual and Gastric Lipases
What digests nucleic acids
- Pancreatic Juice (Ribonuclease and Deoxyribonuclease)
- Nucleosidases
- Phosphatases
How fats absorbed into the bloodstream
Fats = micelle → brush border → TG → chylomicrons → lacteal of villus
How is alcohol consumption affected by food
- If stomach empty, absorption occurs quickly.
- If full, slows down gastric emptying, release into bloodstream slower.
large intestine also called
Colon
Pouches formed in the large intestine
haustra
Haustra
Pouches in the large intestine (the functional unit, equivalent to a lobule in the liver)
Role of the LI
Role: 5% of absorption, fine tuning vitamin absorption and H2o absorption
- Role in bacteria production (good)
- Some ions/vitamins absorption finished up
- Produce bacteria that will help digestion.
Appendicitis
Inflammation of the appendix usually from blockage (Blocking the exit) like foreign body from the large intestine
- Apendix laden with unhealthy bacteria
- WBC count elevated
- Temp elevated
- From pain to rupture can be from 24 hours
- Bacteria easily spreads from abdominal cavity
Anatomy of LI
Small intestine → Ileocecal sphincter → Ascending Colon → Transverse Colon → Descending Colon → Sigmoid colon → Anus → Rectum
Cells in mucosa/submucosa of LI
i) Intestinal Glands: Openings that go down into ducts
ii) Lamina Propria: Connective tissue (In each of the glands/elevations)
iii) Lymphatic Nodules: Green clusters part of immunity system
Goblet cells: produce mucous still
Muscularis layer of LI
Longitudinal and circular muscle
Teniae Colie
The longitudinal muscle in the LI
- Run the length of the colon
Why is Haustra formed
because the longitudinal muscle is contracting producing these pouches
Gastrolienal Reflex:
What controls the movement of the chime from SI to LI
- Hormone gastrin relaxes the sphincter allowing fro movement.
Haustral Churning
Each of the haustra, mix things together and contract and push food forward to next haustra
Peristalsis in LI
: Beginning in transverse colon, “momentum” ensuring that chime is continually pushes forward entire length
What is the muscle in the LI you have control over
External anal sphincter
Defecation reflex
Fecal material from sigmoid colon into rectum.
Stimulation of stretch receptors in rectal wall
Impulses to sacral spinal cord
From cord along parasympathetic route to colon, sigmoid colon, rectum, anus
Longitudinal muscles contract in rectum to shorten
Open internal anal sphincter
simulataneously
Diaphragm and abdominal muscles aid by increasing pressure
Voluntarily control of external sphincter
Dietary Fiber
Indigestible plant material;
insoluble type, skins of fruit and apples – speeds passage of chime through large intestine ;
soluble type: Beans oats, barely, prunes: Mixes with water and slows down passage of chime, binds to cholesterol and reduces blood cholesterol levels
Phases of digestion
Cephalic Phase
- Thinking abt/smelling/seeing food
- Salivation begins (Mainly mouth also stomach preparing for food)
- Limbic syst. role
Gastric Phase
- Begins when food has hit the stomach
- Gastrin increase motility and secretion
- Some control, when stretch receptors tell hypothalamus to stop eating
- Chemoreceptors, tell stomach when it is time to mix and time to push the food forward
Intestinal Phase
- Intestine produces bicarbonaine, pancreas producing hormones towards digestion of contents
Glycemic index
(How quickly do carbohydrates go from digestion to absorption)
- High glycemic (20-30 minutes from breakdown to absorption
- Low glycemic (1.5-2hr to go from digestion to absorption)
- Colorectal cancer
- Cancer of the colon
- Typically latter part into the rectum
- Some genetic element
- Food-based a little bit
Hepatitis
- Inflammation of the liver
- Transfusions, viral
