Anatomy, Digestive System

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Reticular cells

Make up framework of liver.
Small cells that have dense fibers in matrix

Adipose cells

Cells appear to be empty but contain fat molecules.
Fat molecules push the nucleus off to one side.

Main organs of Digestion

Mouth (2) & oral cavity (1)
Esophagus (9)
Stomach (10)
Small intestine (11)
Large intestine (6)

Accessory Organs of digestion

Liver (3)
Gallbladder (4)
Pancreas (5)

Oral Cavity

(1)
Mechanical processing:
Teeth
Tongue
Uvula

Produce enzyme to digest carbs:
Salivary glands (7)

Esophagus

(9)
No digestion occurs here

Digestion function

Physical & chemical digestion (break down molecules)
Absorption (get nutrients into blood)
Modify nutrients (liver)

Digestion purpose (energy)

Carbs (nutrients) become fuel
Fuel is monosacaride (simple sugar)
Energy is in the chemical bonds that hold molecules together
Break apart molecule to release energy

Digestion purpose (structure)

Build body with protein and lipids (fat)
(car is not made of fuel)

Digestion purpose (function)

Life is series of chemical reactions
Enzymes are catalyst for chem. reactions
Every reaction (cellular function) requires right enzyme
Proteins + vitamins = enzymes
Vitamins used to make cells function properly

GI Tract length

25-30'
Needs to be long because digestive process takes time.

GI Tract lining

Epithelial tissue with villi (2) and goblet cells
Lined with mucosa (1)
Lubricates
protects us from digesting ourselves.

Muscularis Externa

(3)
Smooth muscle layer:
Outer layer - longitudinal muscles - peristalsis
inner layer - circular muscles - segmentation

Peristalsis

Longitudinal (smooth) muscles (5) provide directional contractions
Move food through digestive tract

Segmentation

Circular (smooth) muscles (4) provide contractions that squeeze & release
Mixes food with digestive juices

bolus

A mass of food that has been chewed at the point of swallowing.
Digestion begins when it reaches the stomach.

Mesentery

(7)
Connects parietal & visceral layers.
Thin membranous material found between the folds of the small intestine.
Fan shaped
Dorsal side: 6-8"
Ventral side: 20'
Holds abdominal vescera in place but allows movement
Blood vessels, nerves and lymph, embedded between 2 layers, are involved in absorbing nutrients form the small intestine.
Extension of peritoneum

Mesentery (sag.)

(2)
Connects parietal & visceral layers.
Fan shaped
Dorsal side: 6-8"
Ventral side: 20'
Holds abdominal vescera in place but allows movement
Allows for passage of blood vessels, nerves and lymph between 2 layers.
Extension of peritoneum

Peritoneum

Lining of abdominal cavity
Not part of GI tract but holds it in place.
Parietal peritoneum (5) - membrane lining peritoneum
Visceral peritoneum (4) - membrane surrounding organs (2)
Mesentery (1) - connects parietal & visceral layers, extension of the peritoneum.

Parietal peritoneum

(5)
membrane lining peritoneum (abdominal cavity)

Visceral peritoneum

(4)
Membrane surrounding organs in the peritoneum (abdominal cavity)

Greater Omentum

(9)
mesentery that extends from the greater curvature of the stomach and drapes over the intestines like an apron.
Anterior to intestines
Extension of mesentery.
Stores lipids (fats)

Oral Cavity

Tongue
Teeth
Salivary Glands

Tongue

Manipulates food to back of mouth for swallowing
Muscle covered with chemoreceptors
Taste receptors highly concentrated in specific areas on surface
Attached by lingual frenulum
Has papillae on dorsum (superior) surface:
Filaform papillae (1)
Fungiform papillae (2)
Circumvallate papillae (3)

Also used to form words

Filaform papillae

(1)
No taste buds
For friction - to help manipulate food
Has many touch receptors - tip is very sensitive
Fewer temperature receptors - burn easily

Fungiform papillae

(2)
Cover the surface
Have 5 taste buds each, send impulse via facial nerve

Circumvallate papillae

(3)
Approx. 7-9, arranged in V-shape
Located on posterior portion
Have up to 100 taste buds each, send impulse via facial nerve

Taste

mostly involves smell.
Bitter
Sour
Sweet
Salty
Umami

Taste receptors are located all over mouth, uvula and pharynx but more highly concentrated in these areas.

Lingual frenulum

(A)
Attaches tongue on inferior surface

Teeth

2 Sets
Deciduous set (baby teeth), 20
Permanent set (adult), 28-32 (some don't get wisdom or molars)

Incisors

(1)
For tearing food
4/4
wedge shape
1 root

Cuspids

(2)
For tearing food
2/2
conical
1 root

Bicuspids

(3)
For chewing food
4/4
flattened
2-3 roots

Molars

(4)
For chewing food
6/6
flattened
3+ roots

Wisdom teeth

Some people don't have them
Can be hard to remove, roots twisted together.

Enamel

(4)
Hardest substance produced by the body
Only formed when tooth is made
Must last lifetime
Doesn't go into neck (2) - where deterioration occurs

Dentine

(5)
White of tooth under enamel (4)
Made of calcium, not bone
Not as hard as enamel

Pulp

(6)
Contains nerves & blood vessels

Cementum

(9)
Cements tooth to bone
In peridontal joint (synarthrosis, non-movable joint)
Held with connective tissue fibers, must break fibers to pull teeth.

Salivary glands

Secrete amylase (enzyme)
3 glands:
Parotid (2)
Sublingual (1)
Submandibular (3)

Amylase

Produced by the salivary glands
Enzyme that changes carbs (polysaccarides-many monosaccarides) into disaccarides, and then into monosaccarides (single sugar-glucose)

Starch contains many polysaccarides (if chew long enough it breaks down to monosaccaride and begins to taste sweet)

Parotid Salivary gland

(2)
Largest
Most active - produce more spit
Located at angle of mandible, near masseter
Has perotid duct - opens into mouth cavity near second upper molar

Sublingual salivary gland

(1)
near midline, beneath tongue.
Lots of mini ducts under tongue

Submandibular salivary gland

(3)
Lateral to sublingual (1)
Ducts enter floor of mouth (where we gleek)

Mumps

A virus that attacks the perotid salivary gland.
In adults it can attack the pancreas and gonads (causing sterility)

Esophagus

(9)
10-11" long
Empties into stomach (10) at hiatus (inferior to diaphragm)
Opening called esophageal sphincter
Made of smooth muscle
Smooth muscle creates peristaltic action, moving food into stomach

hiatal hernia

tear at hiatus, where esophagus (9) empties into stomach (10)

esophageal sphincter

(1)
The lower sphincter of the esophagus that opens to allow food to enter the stomach.
Also called cardiac sphincter because of location.

Stomach

Functions:
Temporary food storage (3-4 hours)
Mechanical (physical) digestion
Chemical digestion:
produces an enzyme that will digest protein
food digested from the outside - where in contact with digestive enzymes, HCI & pepsin
Produces "Intrinsic factor"

Food enters through esophageal sphincter
then into fundus, body, pylorus
then passes through pyloric sphincter and enters small intestine.

Stomach (temporary food storage)

Capacity: 1-1.5 liters
Can stretch:
The more you overeat, the larger it gets
The larger it gets the more you must eat to feel satisfied

Stomach (mechanical digestion)

Mixes food with chemicals
Can contract in any direction due to 3 muscle layers wall:
Circular (4)
Longitudinal (3)
Oblique (13)

Stomach (Chemical digestion)

Produces 2 chemicals:
HCI - hydrocloric acid
Made by parietal cells in wall of stomach
weakens chemical bonds
lowers threshold to allow reaction to take place more easily

Pepsin - enzyme
Made by Chief cells
1st of several proteolytic enzymes (protein digestor)
Breaks apart protein
Protein = chains of amino acids (300-3000)
Type of protein we make makes us different from each other

Intrinsic Factor

produced in the stomach
Chemical that stimulates erthropoiesis (production of RBC)

Pernicious anemia

lack intrinsic factor (for production of RBC)
treat with Vitamin B12

Fundus

(16)
The large rounded portion of the stomach that expands the most with food.
Nearest the spleen.

Pylorus

(9)
The last part of the stomach, which connects to the duodenum of the small intestine.

Pyloric sphincter

(6)
Opens to allow food to enter into the duodenum.

Cardia

(2)
the area joining the esophagus to the stomach

Gastric Rugae

(12)
Folds (muscular ridges) in wall of stomach that allow it to expand to accommodate food.

HCI (hydrocloric acid)

Part of chemical digestion of stomach
Produced by parietal cells in wall of stomach
weakens chemical bonds
lowers threshold to allow reaction to take place more easily

Pepsin

Part of chemical digestion of stomach
Made by Chief cells
1st of several proteolytic enzymes (protein digestor)
Breaks apart protein
Protein = chains of amino acids (300-3000)
Type of protein we make makes us different from each other

Small Intestine

Longest part of digestive tract, approx. 20' long, 2: diam.
Produces numerous enzymes that will digest protein and carbohydrates.
Where digestion (& absorption of nutrients) occurs
peristalsis pushes material through
3 parts:
Duodenum (1)
Jejunem (3)
Ileum (7)

Duodenum

(3)
approx. 10-12"
first curve of small intestine
Recieves chyme (partially digested food) from stomach
Stimulates:
pancreas to secrete digestive enzymes
liver to secrete bile
Received bile and enzymes through hepatophancreatic sphincter

Jejunum

(3)
Second part of small intestine
approx. 8' long
most of digestion and absorption occurs here
secretes enzymes from cells in wall

Ileum

(7)
Last part of small intestine, connects to the cecum of the large intestine.
approx. 12 ' long
Digestion & absorption of whatever didn't get digested or absorbed previously
Secretes enzymes

Intestinal Vili

(1)
Found lining the jejunem & ileum
Finger-like projections
Surface of each is columnar cells (3) with goblet cells (4)
Where nutrients are absorbed
contains:
Capillary loop
lacteal (4)

Capillary loop in intestinal villa

(5)
comes from Superior or inferior messenteric artery, embedded in the mesentery tissue
goes to liver through hepatic portal
Absorbs:
Digested carbs (monosaccarides)
Digested proteins (amino acids)

Lacteal

(3)
Absorbs digested lipids (fats) in lymph
passes from lymphatic vessel (9) into bloodstream and recombines to form triglycerides (3 fatty acids)

Large intestine

NO DIGESTION OCCURS HERE
Water absorption
Peristalsis pushes material through.
Approx. 5' long, 3" diam.

Consists of:
Ascending colon (3)
Transverse colon (2)
Descemdomg colon (13)

Muscles:
circular (lobes)
Taenia (longitudinal)

Function:
Temporary storage/excretion of digestive waste
Absorbs water
Houses bacteria involved in making vitamins: B complex, K
Propels waste to the anal region

Ileocecal sphincter (valve)

(4)
Opens to allo material to enter the cecum (5) from the ileum (7)

Cecum

(5)
Once food enters here it is considered waste.
The appendix attaches here

Appendix

(6)
No known function

Ascending colon

(3)

Hepatic Flexure
(right colic flexure)

(1)
The bend of the large intestine from the ascending colon to the transverse colon.

Transverse colon

(2)

Splenic flexure
(left colic flexure)

(15)
The bend of the large intestine from the transverse colon to the descending colon.

Descending colon

(13)

Sigmoid colon

(9)

Rectum

(8)

Haustra

(12)
Folds that allows for distention, lobes formed by circular muscles.
performs peristaltic action.

Muscles of large intestine (colon)

Circular (12) - lobes
Taenia (11) - longitudinal muscles

Taenia coli

(11)
Ribbon of smooth muscle that extends the length of the large intestine.
Longitudinal (smooth) muscles of colon
2-3 running the length of each section of the colon
perform peristaltic action in the colon.

Function of large intestine (colon)

1) Temporary storage/excretion of digestive waste:
Food not digested or absorbed
Foreign substances not digested or absorbed

2) Absorbs water

3) Provides vitamins:
B complex (all B vitamins)
vitamin K (important in clotting-makes clotting proteins)
Vitamins produced from resident bacteria (E. coli) in colon

E. coli

Found in large intestine
Processes undigestable carbohydrates (celuose-in cell wall of plants)
Fiber (found in raw plants) helps colon work properly

Produces:
B complex
vitamin K
Methane (from processing fiber)

Pancreas

(19)
Digestive gland
Inferior & posterior to stomach
Produces numerous digestive enzymes
Secretes through pancreatic duct (11) into duodenum
Enzymes digest carbohydrades, proteins and fat.
Partly exocrine - external secretion (enzymes secreted through duct (14 & 18))
partly endocrine - internal secretion (hormones (insulin) secreted through vein)

Type II diabetes

Caused by overuse of pancreas.
Pancreas stops working, doesn't produce insulin

Type I diabetes

Genetic
Pancreas doesn't work properly, doesn't produce insulin.

Liver (structure)

2 major lobes: Right (1-largest), Left (7)
2 minor lobes: located posterior

Contains:
falciform ligament (4), membrane that separates right & left major lobes
round ligament (9), was umbilical vein in embryo (fetal scar)

Liver (functions)

1) Produces/secretes bile (not an enzyme)
2) Produces proteins
3) Destroys old RBC (along w/ spleen), RBC live 120 days
4) Erythropoiesis (makes RBC) in embryo
5) Interconversion of nutrients (transamination & deamination)
6) Neutralize toxins
7) Stores iron, fat soluble vitamins (A, D, E, K), and Glycogen

Bile

Produced in the liver by hepatocytes
Stored in the gall bladder
Does not digest
Emulsifies fat (lipids) - breaks into smaller droplets, increases surface area for digestion
(like homogenization - add substance that breaks fat into smaller droplets that wont glob back together)

Clotting proteins

Prothrombin and Fibrinogen
Produced by liver
Blood doesn't clot until chemicals are released
Fibrinogen turns into fibrin
Need vitamin K for clotting

Erythropoiesis

Produce RBC
Done in liver during embryo stage
After birth, RBC produced in bone marrow

Interconversion of nutrients in Liver

1) Transamination: convert one amino acid into another kind

2_ Deamination: break down amino acids if there is an excess of protein intake (turns to waste)
During starvation body deaminates itself

3) change fats into carbs
too much carbs - becomes fat
too few carbs - convert fat to carb for energy

4) change fructose & galactose to glucose (monosaccarides)
Glucose in the only form cells can burn

Glycogen

"animal starch"
consists of 12-18 glucose units
On demand energy reserve

Hepatic duct

Where bile enters
right (23), left (22)
Common (21)

Cystic duct

(5)

Common bile duct

(9)
Bile passes from here through the hepatopancreatic sphincer and into the duodenem

Pancreatic duct

(14 & 18)
Enzymes travel through this to enter into the duodenum after passing through the hepatopancreatic sphincter.

Hepatopancreatic sphincter

(12)
where the enzymes from the pancreas and the bile from the liver reach the small intestines through the duodenum.

Body of stomach

(14)
The main portion involved with digestion.

Plicae

(1)

Gallbladder

(4)
Stores bile produced by the liver, approx. 30-50ml
Contracts when bile is needed and bile enters cystic duct (5), then enters the common bile ducts, passes through the hepatopancreatic sphincter and enters the duodenum

If the hepatophancreatic sphincter is closed, bile will "back up" in the common bile duct and flow through the cystic duct into the gallbladder (filling the gallbladder).

Gustatory cells

cells that make up taste buds
send signal to brain for interpretation of taste via the cranial nerve VII (facial nerve)

Uvula

(4)
As food passes by this, a signal is sent to brain that swallowing is about to take place
Signal sent to epiglottis (10) causing it to close over opening to trachea (glottis), forcing food to enter esophagus instead of trachea

Palatoglossal (palatopharyngeal) arches

(7)
as food passes, sends signal to brain that swallowing is about to occur, causing the epiglottis to close over opening to trachea.
(Same function as uvula)

esophageal hiatus

where the esophagus passes through the diaphragm.

pyloric sphincter

where food passes from the stomach to the small intestines through peristaltic action

circular muscles of the stomach

(4)

Longitudinal muscles of the stomach

(3)

Oblique muscles of the stomach

(13)

hepatocytes

liver cells
produce bile

Pancreatic lobules

produce numerous digestive enzymes

internal anal sphincter

(3)
opening between the rectum and the anus

External anal sphincter

(4)
Opening that allows waste to leave body.

Heartburn

When a person eats too rapidly, the stomach begins to churn the food before the esophageal sphincter closes. Stomach acid can reflux into the esophagus, causing a burning sensation. (Burning is felt in area of sternum)

Hiatal Hernia

When the esophagus bulges upward through the hiatus (where the esophagus passes through the diaphragm)

Stomach ulcers

Occurs when the acid within the stomach begins to erode the lining of the stomach. This happens when the mucus cells lining the stomach malfunction and do not produce enough mucus to protect the stomach.

Duodenal ulcers

Caused by acid leaving the stomach and entering the duodenum. The duodenum does not have the same type of protection as the stomach.
Can also be caused by a bacterium , heliobacter pylori, in the duodenum Can be treated by antibiotics

Pancreat cancer

Reduces the pancreas' ability to produce insulin in the pancreatic islets. Without insulin cellular metabolism is reduced. Without cellular metabolism, the body cannot produce energy

Reduces the pancreas' ability to produce digestive enzymes in the pancreatic lobules. Without these enzymes, the process of digestion is reduced.

Pancreatic islets

Clusters of cells within the lobules that produce hormones, such as insulin.

Pancreatic lobules

Consists of cells that produce digestive enzymes
(Can't see)

Gallstones

In order to produce concentrated bile, water is absorbed from the gallbladder to the blodstream. The less water in the gall bladder, the more concentrated the bile becomes. If the gallbladder absorbs excess water into the bloodstream, very high concentration of bile salts could result in crystals. Crystals can coalesce together, forming stones.

Hepatitis

Inflammation of the liver due to a virus. Infection damages liver cells, causing the enzyme to leak into the bloodstream.

Hepatitis A (infectious hepatitis) - contracted by ingesting fecal contaminated foods.

Hapatitis B (serum hepatitis) - contracted by sexual contact of infected blood and other body fluids

Hepatitis C (non-A, non-B hepatitis) - Contracted by infected blood or other body fluids.

Jaundice

When the liver malfunctions it has a difficult time incorporating bilirubin into bile. Excess bilirubing enters the bloodstream, causing the skin to appear yellow.

Bilirubin

When erythrocytes breakdown some of their components are converted to this in the liver. It becomes part of bile and is removed from the body via fecal waste.

Digestion

break down large molecules into smaller molecules that can be used by the cells of the body.

Greater curvature of the stomach

(11)
The inferior, convex curve of the stomach.

Lesser curvature of the stomach

(5)
The superior, concave curve of the stomach.

Sigmoid flexure

(10)
The bend of the large intestine from the descending colon to the sigmoid colon.

Lesser Omentum

(3)
Mesentery that extends from the lesser curvature of the stomach to the liver.

Falciform ligament

(4)
Mesentery type tissue that marks the boundary between the right and left lobe of the liver.

Coronary ligament

(5)
The falciform ligament that divides and spreads across the top of the liver, just inferior to the diaphragm.

Hepatocytes

Cells of the liver that produce bile.

Lipase

the enzyme that does the digestion of fat.

Fundus of the liver

(1)
The large rounded portion of the liver on the superior, right side.

Fundus of the gallbladder

The rounded portion of the gallbladder

Pancreatic head

(3)
adjacent to the duodenum

Pancreatic tail

(6)
the narrow portion, nearest the spleen

Pancreatic body

(5)
Main portion between the head (3) and the tail (6)

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