What are the organs of the Alimentary Digestive System?
- Small Intestine
- Large Intestine
What are the 2 parts of the digestive system?
- Alimentary Canal
- Accessory Digestive Organs
What does digestion do?
- Breaks down digested food
- Absorbs nutrients into the blood
What is metabolism?
Production of cellular energy (ATP)
What is the uvula?
Fleshy projection of the soft palate
What is the hard palate?
Anterior Roof of mouth
What is the soft palate?
Posterior roof of mouth
What is the vestibule?
Space between lips externally and gums internally
What is the oral cavity?
Area contained by the teeth
Where is the tongue attached?
Hyoid and Styloid processes of the skull by the lingual frenulum
What are the parts of the pharynx?
- Nasopharnyx - not part of the digestive system
- Oropharynx - posterior to oral cavity
- Laryngopharynx - connected to esophagus
What does the pharynx do?
Allow food and air to pass
What are the 2 muscle layers of the esophagus?
- Longitudinal Inner Layer
- Circular Outer Layer
What is peristalsis?
Contraction of the muscle layers to move substances (like food)
Where is the esophagus?
- From pharnyx to stomach through diaphragm
- Only good goes through the esophagus
What is the mucosa?
- Inner most layer
- Moist membrane
What is the submucosa?
- Layer just beneath the mucosa
- Soft connective tissue with blood vessels
What is muscularis externa?
- Inner circular layer
- Outer longitudinal layer
What is serosa?
Outer most layer - visceral peritoneum
What is the alimentary canal nerve plexuses?
- Submucosal Nerve Plexus
- Myenteric Nerve Plexus
- Subserous Plexus
Where does food enter the stomach?
Where is the stomach?
Left side of abdominal cavity
4 regions of the stomach
- Cardiac Region - near the heart
- Phylorus - funnel shaped terminal end
Where does food empty into the small intestine?
What are the external regions of the stomach?
- Lesser Curvature
- Greater Curvature
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
What does the stomach do?
- Stores food
- Breaks food down
- Begins breakdown of protiens
- Delivers chime to the small intestines
What kind of tissue is the mucosa of the stomach?
Simple Columnar Epithelium
What do the gastric glands produce in the stomach?
What do parietal cells produce in the stomach?
What do endocrine cells produce in the stomach?
What do chief cells produce in the stomach?
Pepsinogens - protien digesting enzymes
What do the mucous neck cells produce in the stomach?
sticky alkaline mucous
What are gastric pits?
Pits formed by folded mucosa
What is the small intestine?
Body's major digestive organ that absorbs nutrients into the blood
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
How does digestion in the small intestine take place?
- Enzymes mix with chime
- Bile enters from the gallbladder
What are the vill of the small intestine and what do they do?
Small fingerlike structures that give the small intestine more surface area.
What are the microvilli of the small intestine and what do they do?
Small projections of the plasma membrane found on absorbptive cells
What structures are involved in the absorption of nutrients?
- Absorptive cells
- Blood capillaries
- Lacteals (special lymphatic capillaries)
Which part of the small intestine has peyers patches?
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
What are the 5 structures of the large intestine?
- Cecum - first part
- Appendix - lympatic tissue, hangs from cecum
What are the 4 parts of the colon?
- Sigmoid (s-shaped)
What is the teniae coli?
Band of muscle that run along the colon
What are the accessory digestive organs?
- Salivary Glands
- Gall bladder
What are the 3 saliva producing glands?
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
What is a full set of teeth?
What are Deciduous teeth?
What are the 4 types of teeth?
What are the regions of a tooth?
- Crown - exposed part
- Neck - region in contact with the gum
- Root - part attached to the bone
What does the pancreas do?
- Produce digestive enzymes, which are secreted to the duodenum
- Produce the hormones Insulin and Glucagon
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
What is bile?
Liquid made of bile salts, pigment, cholesterol, phospholipids and electrolytes, produced in the liver
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.
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
What is segmentation?
Moving materials back and forth to aid in mixing
What are carbohydrates broken down to?
What are protiens broken down to?
What are fats broken down to?
fatty acids and alcohols
What is absorption?
End products of digestion are absorbed in the blood or lymph
What controls digestive activity?
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
How is gastric juice regulated?
Neural and hormonal factors
What causes the release of gastrin in the stomach?
Food presense of falling pH levels
Why does the stomach have to be so acidic?
Provids a hostile environment for microorganisms
What are the protien digestion enzymes?
- Pepsin - regular protiens
- Rennin - milk protien
How long does it take the stomach to empty?
- 4 - 6 hours
- 30ml at a time
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
How do substances get to the liver from the small intestine?
How are lipids absorbed?
How does the large intestine work?
- Bacteria break down nutrients
- Absorbs water
- Absorbs vitamins K and B
How are substances propulsed through the large intestine?
- Sluggish Peristalsis
- 3 - 4 times a day
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
What is catabolism?
- substances broken down to simpler substances
- releases energy
What is anabolism?
larger molecules built from smaller ones
What is glycolysis?
Turns sugar into ATP
What is the Krebs cycle?
Produces carbon dioxide and water from cell respiration
How is fat metabolized?
In the liver, somtimes to make ATP
How is protien metabolized?
- Protiens are conserved by body cells
- Ingested protiens are turned into amino acids
What is the livers role in metabolism?
- Detoxifies drugs and alcohol
- Degrades hormones
- Produces cholesterol, blood protiens
- Plays central role in metabolism
What is glycogenesis?
Glucose molecules converted to glycogen and stored in the liver
What is Glycogenolysis?
Glucose is released from the liver
What is glucogenesis?
Glucose is produced from fats and protiens
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
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
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