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What are the organs of the Alimentary Digestive System?
- Mouth
- Pharynx
- Esophagus
- Stomach
- Small Intestine
- Large Intestine
- Anus
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What are the 2 parts of the digestive system?
- Alimentary Canal
- Accessory Digestive Organs
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What does digestion do?
- Breaks down digested food
- Absorbs nutrients into the blood
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What is metabolism?
Production of cellular energy (ATP)
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What is the uvula?
Fleshy projection of the soft palate
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What is the hard palate?
Anterior Roof of mouth
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What is the soft palate?
Posterior roof of mouth
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What is the vestibule?
Space between lips externally and gums internally
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What is the oral cavity?
Area contained by the teeth
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Where is the tongue attached?
Hyoid and Styloid processes of the skull by the lingual frenulum
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What are the parts of the pharynx?
- Nasopharnyx - not part of the digestive system
- Oropharynx - posterior to oral cavity
- Laryngopharynx - connected to esophagus
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What does the pharynx do?
Allow food and air to pass
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What are the 2 muscle layers of the esophagus?
- Longitudinal Inner Layer
- Circular Outer Layer
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What is peristalsis?
Contraction of the muscle layers to move substances (like food)
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Where is the esophagus?
- From pharnyx to stomach through diaphragm
- Only good goes through the esophagus
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What is the mucosa?
- Inner most layer
- Moist membrane
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What is the submucosa?
- Layer just beneath the mucosa
- Soft connective tissue with blood vessels
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What is muscularis externa?
- Inner circular layer
- Outer longitudinal layer
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What is serosa?
Outer most layer - visceral peritoneum
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What is the alimentary canal nerve plexuses?
- Submucosal Nerve Plexus
- Myenteric Nerve Plexus
- Subserous Plexus
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Where does food enter the stomach?
Cardioesophageal Sphincter
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Where is the stomach?
Left side of abdominal cavity
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4 regions of the stomach
- Cardiac Region - near the heart
- Fundus
- Body
- Phylorus - funnel shaped terminal end
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Where does food empty into the small intestine?
Pyloric Sphincter
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What are the external regions of the stomach?
- Lesser Curvature
- Greater Curvature
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What are the layers of the peritoneum?
- Lesser Omentum - attaches the liver to the lesser curvature
- Greater Omentum - attachers greater curvature to posterior body wall
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What does the stomach do?
- Stores food
- Breaks food down
- Begins breakdown of protiens
- Delivers chime to the small intestines
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What kind of tissue is the mucosa of the stomach?
Simple Columnar Epithelium
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What do the gastric glands produce in the stomach?
Gastric Juice
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What do parietal cells produce in the stomach?
Hydrochloric Acid
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What do endocrine cells produce in the stomach?
Gastrin
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What do chief cells produce in the stomach?
Pepsinogens - protien digesting enzymes
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What do the mucous neck cells produce in the stomach?
sticky alkaline mucous
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What are gastric pits?
Pits formed by folded mucosa
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What is the small intestine?
Body's major digestive organ that absorbs nutrients into the blood
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What are the subdivisios of the small intestine?
- Duodenum - Attached to the stomach, curves around head of pancreas
- Jejunum - Attaches to the duodenem
- Ileum - Extends from jejunum to large intestine
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How does digestion in the small intestine take place?
- Enzymes mix with chime
- Bile enters from the gallbladder
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What are the vill of the small intestine and what do they do?
Small fingerlike structures that give the small intestine more surface area.
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What are the microvilli of the small intestine and what do they do?
Small projections of the plasma membrane found on absorbptive cells
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What structures are involved in the absorption of nutrients?
- Absorptive cells
- Blood capillaries
- Lacteals (special lymphatic capillaries)
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Which part of the small intestine has peyers patches?
Submucosa
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What are the functions of the large intestine?
- DOES NOT PARTICIPATE IN DIGESTION
- Absorbs water
- Creates feces
- "Goblet cells" produce mucous to act as a lubricant
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What are the 5 structures of the large intestine?
- Cecum - first part
- Appendix - lympatic tissue, hangs from cecum
- Colon
- Rectum
- Anus
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What are the 4 parts of the colon?
- Ascending
- Transverse
- Descending
- Sigmoid (s-shaped)
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What is the teniae coli?
Band of muscle that run along the colon
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What are the accessory digestive organs?
- Salivary Glands
- Teeth
- Pancreas
- Liver
- Gall bladder
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What are the 3 saliva producing glands?
- Parotid
- Submandibular
- Sublingual
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What is saliva and what does it do?
- Mixture of mucous and serous fluids
- Helps form food bolus, dissolves chemicals so they can be tasted, begins starch digestion
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What is a full set of teeth?
32 teeth
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What are Deciduous teeth?
Baby teeth
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What are the 4 types of teeth?
- Incisors
- Canines
- Premolars
- Molars
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What are the regions of a tooth?
- Crown - exposed part
- Neck - region in contact with the gum
- Root - part attached to the bone
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What does the pancreas do?
- Produce digestive enzymes, which are secreted to the duodenum
- Produce the hormones Insulin and Glucagon
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What is the liver?
- Largest gland in the body
- Located on right side under diaphragm
- Connected to gall bladder via hepatic duct
- Has 4 lobes
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What is bile?
Liquid made of bile salts, pigment, cholesterol, phospholipids and electrolytes, produced in the liver
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What is the gall bladder?
Sac found in the hollow foss of the liver that receives and stores bile from the cyctic duct, and sends it to the duodenum in the presense of fatty food.
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2 Processes of the digestive system
- Ingestion - getting food into the mouth
- Propulsion - moving food from one region to the other
- Mechanical Digestion - chewing in mouth, churning in stomach, segmentation on small intestine
- Chemical Digestion - enzymes break down food molecules
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What is segmentation?
Moving materials back and forth to aid in mixing
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What are carbohydrates broken down to?
Simple sugars
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What are protiens broken down to?
amino acids
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What are fats broken down to?
fatty acids and alcohols
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What is absorption?
End products of digestion are absorbed in the blood or lymph
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What controls digestive activity?
Parasympathetic division
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What are the 2 types of deglutition (swalling)?
- Buccul phase - in the mouth, voluntary
- Pharyngeal-esophagal phase - Involuntary, all passageways exept the stomach are blocked
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How is gastric juice regulated?
Neural and hormonal factors
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What causes the release of gastrin in the stomach?
Food presense of falling pH levels
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Why does the stomach have to be so acidic?
Provids a hostile environment for microorganisms
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What are the protien digestion enzymes?
- Pepsin - regular protiens
- Rennin - milk protien
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How long does it take the stomach to empty?
- 4 - 6 hours
- 30ml at a time
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Why do pancreatic enzymes play the major role in digestion?
- Digestion of starch
- Half of all protien digestion
- Fat digestion
- Neutralizes chyme
- Digests nucleic acids
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How do substances get to the liver from the small intestine?
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How are lipids absorbed?
Diffusion
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How does the large intestine work?
- Bacteria break down nutrients
- Absorbs water
- Absorbs vitamins K and B
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How are substances propulsed through the large intestine?
- Sluggish Peristalsis
- 3 - 4 times a day
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What are the 6 nutrients?
- Carbohydrates - plants
- Lipids - saturated/unsaturated fats & cholesterol
- Protiens - contain amino acids
- Vitamins - found in all major food groups
- Minerals - veggies, legumes, milk, meat
- Water - everything is dependant on water
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What is catabolism?
- substances broken down to simpler substances
- releases energy
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What is anabolism?
larger molecules built from smaller ones
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What is glycolysis?
Turns sugar into ATP
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What is the Krebs cycle?
Produces carbon dioxide and water from cell respiration
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How is fat metabolized?
In the liver, somtimes to make ATP
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How is protien metabolized?
- Protiens are conserved by body cells
- Ingested protiens are turned into amino acids
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What is the livers role in metabolism?
- Detoxifies drugs and alcohol
- Degrades hormones
- Produces cholesterol, blood protiens
- Plays central role in metabolism
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What is glycogenesis?
Glucose molecules converted to glycogen and stored in the liver
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What is Glycogenolysis?
Glucose is released from the liver
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What is glucogenesis?
Glucose is produced from fats and protiens
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What is the function of cholesterol?
- Structural basis for steroid hormones and vitamin D
- Building block of plasma membranes
- Cannot freely circulate in the blood stream
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What is BMR (basic metabolic rate?)
- Amount of heat produced by the body per unit of time at rest
- Small bodies have higher BMR
- Males have higer BMR than females
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What is TMR (total metabolic rate?)
- Amount of kilocalories the body must consume to fuel ongoing activities
- TMR must equal calories consumed to maintain weight
- TMR increased with bodily activity
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