Digestive System(A&P) Flashcards
Divisions of the Digestive System
1) Alimentary Tract, Gastrointestinal Tract, Digestive Tract(tube like structure that extends from the mouth to the anus
2) Accessory Organs(Organs necessary for digestion but not part of the Gi tract(Salivary glands, liver, gall bladder, pancreas
Functions of the Digestive System(Ingestion)
- taking in food
- eating
Functions of the Digestive System(Digestion)
- breakdown of food we eat
- mechanical digestion: breaking large particles to small particles
- chemical digestion: breakdown of large molecules into small ones that can be absorbed
Functions of the Digestive System(Absorption)
-transfer of digested nutrients from the gi tract to the bloodstream
Functions of the Digestive System(Elimination)
-undigested material eliminated from tract; deformation
Functions of the Digestive System?
- Ingestion
- Digestion
- Absorption
- Elimination
Walls of the digestive tract(Innermost to outermost)
- Mucosa
- Sub Mucosa
- Muscle
- Serosa
Mucosa
- innnermost layer
- mucous membrane(goblet cells make mucous)
- protects underlying tissues
- many secretory gland
- ph of stomach=1-2 acidic
Muscle
-smooth muscle
most of gi tract has 2 layers:
-inner layer has fibers that are arranges in a circular pattern(contraction narrows the lumen)
-outer layer has fibers that are arranged in a longitudinal pattern(contractions make the gi tract shorter)
-combination of contractions of both muscle layers produce peristalsis
-stomach has an extra layer(total of 3 layers) to strengthen it and help with mixing food and digestive enzymes
Serosa
- visceral layer of the peritoneum is part of the wall of the gi tract
- esophagus is covered with fibrous connective tissue
- parietal layer lines the abdominal cavity
Peritoneal Membrane
- forms a large, flat, folded structure
- helps to anchor digestive organs
- contains: blood vessels, lymph vessels and nerves
- separates abdominal cavity into compartments which help to restrict the spread if infection
- membranes behind the digestive organs are the mesentery and mesocolon, membrane in front are the greater and lesser omentum
Mouth; Oral Cavity; Buccal Cavity(Function)
-ingestion
-mastication(chewing
mechanical digestion of food in smaller particles performed mainly by the teeth assisted with tongue, cheeks, lips, mixes food with saliva for lubrication
-saliva begins the chemical digestion of starch
-deglutition; swallowing, amount of food we swallow is bolus
Mouth; Oral Cavity; Buccal Cavity(Structure)
- naso cavity separated from oro-cavity by palate
- soft and hard palate
- uvula posterior margine of the soft palate
- gums/gingiva=ridges of mucosa that surrounds the base of each tooth
- maxillae=upper jaw
- mandible=lower jaw(only movable bone in skull
Mouth; Oral Cavity; Buccal Cavity(Accessory Structure)-Tongue
Tongue
- muscular organ that is anchored by the frenulum to the floor of the mouth
function: taste bud, help with chewing, swallowing, and speech - sublingual capillary bed
Mouth; Oral Cavity; Buccal Cavity(Accessory Structure)-Salivary Glands
Salivary Glands -three pairs: Parotid,Submandibular,Sublingual Parotid -anterior and inferior(largest Submandibular -near body of mandible Sublingual -under tongue Function: -secrete saliva -moistens food -helps with mastication and deglutition -amylase converts starch to sugar
Mouth; Oral Cavity; Buccal Cavity(Accessory Structure)-Teeth
Teeth
- made of dentin(calcium based salt)
- crown projects above the gun and is covered w/ enamel
- root: under the gum line and anchors tooth in the jaw
- overcourse of lifetime a person will have 2 sets of teeth
- decidous teeth(baby teeth) 20 total
- permanent teeth(32 total)
Pharynx(throat)
- common passage way for resp and gi system
- deglutition: tongue pushes a bolus of food mixed with saliva into the pharynx
- uvula extension of the palate, doses the nasopharynx during swallowing
- epiglottis covers larynx during swallowing
Esophagus(Gullett)
- muscular tube about 10inces long
- moves food mixed with mucus by peristalsis into stomach
- travels through the esophageal hiatus in the diaphragm before it reaches the stomach
Stomach(Function)
- food storage
- churn
- digestion
- HCL: kills pathogen/most that reach stomach
- Pepsin: begins chemical digestion in stomach
Stomach(location)
-upper right quadrant
Stomach(Muscle Layers, spincters)
-J shaped organ
-2spincters
-cardiac sphincter(lower esophageal spinster) at entrance
-pyloric sphincter at the exit
Three layers of muscle
-circular, longitudinal, oblique(strengthens for mixing/churning)
-when empty it has folds called rugae
Regions
Fundus -superior rounded edge of stomach -part next to diaphragm Body -greater and lesser curvature Pylorus -next to pyloric spinster
Gastric Pits
- cells that produce secretions
- secretion of gastric pits are called gastric juices
Goblets Cells
- make mucus
- protects lining of stomach
Chief Cells
- make digestive enzymes(pepsin)
- begins chemical digestion of protein
Parietal Cells
- make HCL and intrinsic factor
- HCL- part of the first line of immune defense
- Intrinsic factor to absorb b12
- not enough b12 can cause pernicious anemia
Control of Stomach Activity(Nervous Control)
- vagus nerve
- parasympathetic nerve(Cr Never 10)
- promotes stimulates system
Control of Stomach Activity(Hormonal Control)
gastrin produced by G cells in stomach in response to:
- stomach distension
- presence of caffeine in stomach
- presence of partially digested protein in the stomach
Function of gastrin
- secretion of large amounts of gastric juice
- closure of the cardiac sphincter
- food leaves stomach as chyme(highly acidic) through pyloric sphincter and enters the small intestine
Small Intestine(Structure)
- longest part of the digestive tract
- 20ft long and 1 inch in diameter
- lining is folded and it contains millions of finger like projections called villi
- villi increases surface area for absorption
- each villus contains blood capillaries and a lacteal
- lacteal is a lymph capillary
- lacteal: absorbs fat and fat soluble vitamins
Small Intestine(Divisions)(Duodenum)
- First 12 inches of small intestine
- C shaped
- receives chyme from stomach and digestive secretions from the liver and pancreas
- has many mucous secreting glands to protect it from acidic chyme
- most digestion and absorption takes place here
Small Intestine(Divisions)(Jejunum)
- 8ft long
- some digestion and absorption takes place
Small Intestine(Divisions)(IIeum)
- 12ft long
- ends at the ileocecal valve-valve btw ileum and cecum
- has peyers patches
- peyer patches: patches pf lymphatic tissue fluid found at distal end of ileum. prevent invasion of small intestine by normal flora from large intestine
Enzymes
secreted by small intestine
Lactase
enzyme that takes disaccharide(LACTOSE) and breaks down into two monosaccharides(GLACTOSE & GLUCOSE)
Sucrase
enzyme that takes disaccharide(Sucrose) and breaks down into two monosaccharides(FRUCTOSE & GLUCOSE)
Maltase
enzyme that takes disaccharide(MALTOSE) and breaks down into two monosaccharides(GLUCOSE & GLUCOSE)
Digestion in Small Intestine:
Enzymes secreted by the pancreas
Digestion in small intestine gets help by the pancreas:
- pancreatic amylase=acts on polysaccharide
- pancreatic lipase=acts on lipids
- pancreatic enzymes=trypsin and chymotrypsin acts on protein
- bile(emulsify fat) is secreted by the liver
Large Intestine(Structure)
- about 5ft long and 2.5inches in diameter
- begins at the ileocecal valve and ends at the anus
- walls from a series of pouches with creases(tinea coli)
Seven Subdivision of the Large Intestine:
- Cecum
- Ascending Colon
- Transverse Colon
- Descending Colon
- Sigmoid Colon
- Rectum
- Anal Canal
- Cecum
- receives material from the ileum
- attached to cecum is vermiform appendix
2.Ascending Colon
- located on the right side of the abdominal cavity
- extends from the cecum to the hepatic flexure
3.Transverse Colon
-extends across the abdomen from the hepatic flexure to the splenic flexure
4.Descending Colon
- located on the left side of the abdomen
- extends from the splenic flexure to the sigmoid flexure
5.Sigmoid Colon
- starts at the sigmoid flexure and empties into the rectum
- S shaped segment which bends posteriorly
6.Rectum
- last 15cm of large intestine
- stores fecal matter
7.Anal Canal
-last portion of the rectum
-contains two sphincter
internal anal sphincter(involuntary)
external anal spinster(voluntary)
Large Intestine(Function)
-absorption of water
-absorption of bile salts
normal flora in the large intesting produce:
-vit K
-biotin
-vit b12
-stores waste
-defacation
Pathway of Food
- Mouth(tongue, teeth, saliva(chemical digestion of starch in mouth)
- Pharynx-orophrynx-laryngopharnx-uvula-epiglottis
- Esophagus
- Stomach-mechanical and chemical digestion, cardiac sphincter and pyloric sphincter
- Small Intestine-Duodenum,Jejunum,Illium
- Large Intestine-cecum,ascend colon,transverse colon,descending colon,sigmoid rectum
- Anus-internal anal sphincter and external anal sphincter
Pancreas
Accessory Digestive organ
-located posterior to the stomach in the upper L quadrant
Produces pancreatic enzymes:
-Pancreatic amylase
-Pancreatic Lipase
-Proteolytic Enzymes(Trypsin-Chymotrypsin)
-produces sodium bicarbonate(alkaline-substance)
-Neutralize Chyme
Liver
Accessory Digestive organ
- larget gland located in RUQ
- two lobes right and left
- right lobe is larger
- left extends across the abdomen
- recieves blod from the gi tract and spleen by the hepatic portal vein
Liver(Functions)
Accessory Digestive organ
-stores glycogen, vitaminsADEK,Bcomplex, and iron(rbc removed by the spleen)
-synthesis of plasma proteins(albumin and clotting factors(prothrombin/fibrinigen))
-albumin=osmotic pressure, return of fluid from tissue to blood stream
-destroys old rbcs
-detoxifies harmful substances
-modifies lipids to enhance their use by cells
-synthesis of urea
-synthesis of bile
bile
-bile is needd for digestion of lipids
-bile(bile salts) emulsify fat
-emulsify means to break up into small droplets
-bile is a green secretion
Bile
- systhesis by the liver
- bile is needd for digestion of lipids
- bile(bile salts) emulsify fat
- emulsify means to break up into small droplets
- bile is a green secretion
Gall Bladder
Accessory Digestive organ
- muscular sac/pouch on the the inferior surface of the liver which stores bile
- bile ismade by the liver and flows into the hepatic ducts
- travels via cyctic duct to the gall bladder
- gall bladder absorbs water from concentrate bile
- chyme enters the duodenum, the gall bladder contracts and sends bile through the cyctic duct to the common bile duct to the duodenum
Enzymes and their actions
- enzymes and protein catalysts that speed the reaction invovled in digestion
- all digestion reactions are catabolic(breakdown)
- hydrolysis=type of chemical reaction that digestion reactions belong to, splitting apart using water
Amylase
- Produced by: Salivary Glands, Pancreas
- Location of action: Mouth, Duodenum
- Acts on: Starch or CHO and turns into disachccride
Pepsin
- Produced by: chief cells in stomach
- Location of action: stomach
- Acts on: protein-peptide
HCL
- Produced by: parietal cells in stomach
- Location of action: stomach
- Acts on: protein
Bile
- Produced by: Liver
- Location of action: Duodenum
- Acts on: Emulsifies fat
Lipase
- Produced by: Pancreas
- Location of action: Duodenum
- Acts on: lipids—>faty acids and glycerol
Tripsin/Chymotrypsin
- Produced by: Pancreas
- Location of action: Duodenum
- Acts on: Protein—> peptides
Sucrase,Maltase,Lactase
- Produced by: Duodenum
- Location of action: Duodenum
- Acts on: Disaccharides—>Monosacccharides
Peptidases
- Produced by: Duodenum
- Location: Duodenum
- Acts on: Peptides—–>amino acids
Carbohydrate Digestion(digestive process)
- starts in the mouth with salivary amylase
- continues in the small intestine w/
- pancreatic amylase and
- lactase: digest lactose into glucose and galactose
- maltase: digest maltose into 2 glucose molecules
- sucrase: digest sucrose into glucose and fructose
- end product of starch=carbohydrate
- digestion is monosaccaride
Protein Digestion(digestive process)
- starts in the stomach with HCL and pepsin
- continues in the small intestine with trypsin and chymotrypsin
- from the pancreas and peptidases secreted by the small intestine
- end product of protein digestion is amino acid
Fat Digestion(digestive process)
- starts in small intestines
- bile(bile salts) emulsify fat
- lipase from the pancreas digests into fatty acids and glycerol
- end product of fat digestion is fatty acids and glycerol
Nervous Control
-parasympathetic stimulation(vagus nerve) increase the production of digestive secretions and increase motility of the Gi Tract
parasympathetic stimulation occurs due to:
- sight and smell of food
- stomach distention
- stretching causes smooth muscle to contract
- presence of food in stomach stretches smooth muscle wall causing it to contract activating parasympathetic stimulation
-sympathetic stimulation leads to a decrease in production of digestive secretions and decreases motility of the Gi tract
Hormonal Control
Gastrin secreted by g cells in the stomach
- in response to stomach distention, presence of caffeine in stomach, presence of partially digested protein in the stomach
- function of gastrin: secretion of large amounts of gastric juice, and closure of cardiac sphincter
Hormonal Control (Small intestine Secretes 3 Hormones) GIP=Gastric Inhibitory Peptide
- -secreted when chyme enters small intestine
- inhibits the secretion of gastric juices and decreases gastric motility
- stimulates the release of insulin
Hormonal Control
(Small intestine Secretes 3 Hormones)
Secretin
- secreted when chyme enters the small intestinge
- function of secretin; decrease gastric secretions
- stimulate the release of water and bicarbonate from the pancreas
- stimulate the release of bile from the liver
Hormonal Control
(Small intestine Secretes 3 Hormones)
Cholecyctokinin
-cck is secreted when fat enters the small intestine
Function of cck
-stimulate the release of digestive enzymes from the pancreas
-stimulates the release of bile from the gallbladder
-inhibits gastric emptying
Small Intestine(absorption)
- absorption of digested starch, protein, lipids
- villi increase surface for absorption
- peristalsis causes movement
- villi has blood capillary(monosaccharide/aminoacids) and lacteal capillary(fattyacid/glycerol)
Large Intestine(absorption)
- absorption of water, vitamins, and minerals
- most of what is absorbed is water
- vitamin k in large intestine absorbed
- minerals
Defecation
- a spinal reflex initiated by the presence of fecal matter in the rectum
- internal anal sphincter(involuntary)
- external anal sphincter(voluntrary)
- both must relax in orer for defecation to take place
Effects of Aging on Digestive System:
- decrease sense of taste and appetite
- decrease in secretions of the Gi system
- decrease in peristalsis which leads to an increase in constipation
- decreased production of intrinsic factor may lead to pernicious anemia
- decreased muscle tone of the cardiac sphincter leads to an increase in GERD/pylosis
