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