3.3 Digestive System Flashcards
The digestive tract is a long tube-like structure from the _____ to the ____ that is typically considered _______ the body
mouth, anus, outside
How is the digestive tract separated?
Different sphincters exist along the track
How long does it take for material to pass through the digestive tract? Where does it take the longest?
Around 2 days. Most of the time spent in the large intestine
Surround the digestive tract is a _-layer wall that all faces into the lumen. What is the lumen?
7, where digestive practices occur
What is the mucosa?
1st layer from inner small intestine, where nutrients are absorbed
What is the submucoso?
3rd layer from inner small intestine, where blood vessels are (where nutrients get sent)
What is the muscularis?
5th layer from inner small intestine, smooth muscles (longitudinal and circular smooth). Helps us change diameter for tract
What is the serosa?
7th layer from inner small intestine, helps bind digestive tract to nearby structures and provides fluid motion
How does the mouth contribute to digestion?
- Teeth rip food apart
- Tongue pushes food to teeth and mixes with saliva
- Salivary glands secrete saliva, which contain amylase, lingual lipase, lubrication, and lysozyme (disinfectant)
What is a bolus?
A ball of food when it leaves the mouth
How does the pharynx contribute to digestion?
Just a common passage for food, has no active digestion or absorption.
What is the epiglottis?
A muscle flap that directs food from the throat posterially into the esophagus instead of the trachea (windpipe)
What is peristalsis?
The circular smooth muscles contracting in a wave like fashion to push food down. For example, in the esophagus
How does the stomach contribute to digestion?
- Temporary reservoir for food (4-5 hours) before small intestine is ready for it.
- 3 layers of muscle allow it to churn (longitudinal, circular, and diagonal)
What is chyme?
The form food is when it leaves the stomach in a semi-liquid form
What is in gastric juice? What is the purpose for each component?
- Mucus: lubrication, site for chemical reactions and protection
- Gastric lipase: break down lipids
- Hydrochloric Acid: Unravels proteins, activate pepsinogen
- Pepsinogen: Becomes pepsin, which digests protein
How does the small intestine contribute to digestion?
Primary site of digestion and absorption
What are the 3 sections of the small intestine? Where are the located?
Duodenum (beginning), jejunum (middle), and ileum (end)
What is the length and surface area of the small intestine?
6m, size of tennis court due to folds, villi, and micro villi
How is the body protected from the stomach’s gastric juice?
Lower esophageal sphincter and pyloric sphincter close as stomach churns food and gastric juice
What are villis?
Functional units of the small intestine that actually absorb nutrients into blood vessels.
What are micro villis?
Additional villis and villis that increase surface area and secrete some digestive enzymes
What is the brush boarder? What are brush boarder enzymes?
Brush boarder is the collection of micro villi as it looks like a brush stroke
Brush boarder enzymes are enzymes secreted by the micro villi
What are some absorption processes that nutrients can use to be taken into the villi?
Osmosis - Water
Passive diffusion - lipids, fat-soluble vitamins
Facilitated diffusion - fructose
Active transport (requires energy) - glucose, amino acids
What are protein transporters?
Proteins embedded in the cell that allow nutrients to pass through
Which types of absorption use protein transporters?
Facilitated diffusion and active transport
How does the large intestine contribute to digestion?
Any unabsorbed material is either packaged for removal or acted upon by bacteria
Where does the food spend most of it’s time within the digestive tract?
Large intestine
How long is the large intestine?
1.5 meters
What is the main part of the large intestine?
The colon
What is the microbiota?
All the non-human organisms found in our body
What is a microbiome?
The genetic material of the non-human organisms found in our body
What does the microbiota help with?
- Vitamin K, B2, and B12 synthesis
- Energy harvesting (ferment some fibres)
- Health/disease
- Appetite
- To be determined
Where is the largest population of microbiota found in?
Large intestine
How many species of bacteria can be found in the microbiota?
300-500
What are some accessory organs to the digestive tract?
Liver, pancreas, and gallbladder
What is the enteric nervous system?
The collective entity of all nerves and nerve plexuses found in the digestive tract
What are the 3 main salivary glands?
Parotid, submandibular, and sublingual
What sphincter controls access to the small intestine?
pyloric
What stomach has many _______ that increase surface area and allow more stomach cells to be involved in digestion
crypts
What are enterocytes? What is there role?
Small intestine cells that line the villus surface. To increase surface area
What are lacteals?
A lymphatic vessel where larger lipids and fat soluble vitamins are absorbed into in the small intestine
What is the thoracic duct?
A vessel that drains items from the lacteal into the bloodstream.
