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304 Cards in this Set
- Front
- Back
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Digestion
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Breaking down food to a size able to cross plasma membranes of cells
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Importance of digestion - to provide what two things?
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Provide:
Energy for body metabolism Basic building blocks for the body to make substances necessary for life |
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Metabolism
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chemical reactions of the body
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Two primary processes/functions of digestive system:
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- Digestion
- Absorption |
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Digestion in three words.
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breakdown of food
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Two kinds of digestion
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Mechanical
chemical |
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Mechanical digestion
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chewing, churning
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chemical digestion
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like with digestive enzymes
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Absorption
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The process of getting digested food from the digestive tract to the blood
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________: Use of the products of digestion by cells in the chemical reactions of the body
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Metabolism
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Summary of overall process of digestion is four scientific terms:
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Digestion
Absorption circulation Metabolism |
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Structure of digestive system is in two parts
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Digestive tract
Accessory organs |
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Central muscular tube/passageway from mouth to anus?
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Digestive tract
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What part of the digestive system is like a hallway through a building or a tunnel through a mountain?
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Digestive tract
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Four other names for the digestive tract
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Alimentary tract
Food tract Gastrointestinal tract GI tract |
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_____________: central continuous space/opening along the length of the digestive tract
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Lumen
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Accessory organs are what?
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Organs connected to digestive tract by a duct
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Accessory organs release what into what to aid digestion?
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Release substances into digestive tract
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The accessory organs include... (4)
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Salivary glands
Liver Gallbladder Pancreas |
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4 wall components of the wall of the digestive tract (inner to outermost)
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Mucous membrane
Submucosa Smooth muscle layer Serous membrane |
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Mucous membrane is a.k.a.
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a.k.a. mucosa
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What tissue makes up the mucous membrane of digestive tract wall?
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Simple columnar epithelium
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The mucous membrane of the digestive tract is made of simple columnar epithelium except in these three areas. What are those areas and what tissue is found there?
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Stratified squamous epithelia in areas of the mouth, esophagus & anus
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Why is the mucosa of the mouth area, esophagus, & anus made of stratified squamous epithelia?
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For protection of the lining
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What tissue makes up the submucosa of the digestive tract?
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Connective tissue layer
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Connective tissue layer (submucosa) of digestive tract contains what two things?
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Blood vessels & lymphatics
Nerve plexus |
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Why does the submucosa have blood vessels and lymphatics?
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for absorption
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Nerve plexus
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Nerve network
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Why does the submucosa contain a nerve plexus?
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To control digestive tract lining & muscle movements
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Smooth muscle layers of digestive tract are a.k.a.
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muscularis
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Two layers of the muscularis of digestive tract
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Inner circular
Outer longitudinal |
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How is are the smooth muscle layers of the esophagus special?
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Tough skeletal muscle in its upper portion
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How are the smooth muscle layers of the stomach special?
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Has additional inner oblique smooth muscle layer to enhance its ability to churn food (so three muscle layers)
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Muscularis of digestive tract produces movements. What two kinds of movements?
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Segmentation
Peristalsis |
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Digestive tract movements: Segmentation
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Mixing movements (sloshing back and forth) → mix food with digestive juices
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Which part of the digestive tract especially sloshes food back and forth?
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The small intestine
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Digestive tract movements: peristalsis
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Peristalsis:
propelling movements → move food along tract |
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Serous membrane is a.k.a.
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serosa
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Function of digestive tract's serous membrane
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covers digestive organs in abdominopelvic cavity
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Serous membrane is made of what two types of tissue?
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Made of simple squamous epithelium + loose CT
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Which part of the digestive tract's wall is a thin, moist membrane that contributes to the peritoneum?
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Serous membrane
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Peritoneum
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Inner & outer lining of abdominopelvic cavity
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Why does the serous membrane cover digestive organs?
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To allow organs to slide easily past one another
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Serous membrane gives rise to these supporting structures.
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Mesenteries
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Mesenteries location
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Tough membranes attached to GI organs
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Mesenteries function
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Convey nutrients from GI organs in its many blood vessels to the liver
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Organs of the digestive system (9)
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1. Mouth
2. Pharynx 3. Esophagus 4. Stomach 5. Small intestine 6. Large intestine 7. Rectum 8. Anus 9. Accessory organs |
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Scientific term for the mouth
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Oral cavity
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Three major structures of mouth
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- hard palate
- soft palate - tongue & its muscles |
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Hard palate
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Anterior roof of mouth
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What is the hard palate made of?
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Bone covered by mucosa
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Soft palate
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posterior roof of mouth
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What is the soft palate made of?
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Muscle covered by mucosa
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Where are the tongue & its muscles located?
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Floor of mouth
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Functions of the mouth (3)
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- Ingestion
- Prepare food for digestion - Begin some digestive processes |
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Ingestion
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Receive food
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The mouth begins some digestive processes, especially digestion of this.
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carbohydrate [starch] digestion
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Accessory structures of the mouth (3)
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- Salivary glands
- Tongue - Teeth |
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What is the major component of saliva?
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amylase
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Amylase
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an enzyme for starch digestion
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Tongue's multiple functions (4)
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Manipulation/mechanical disruption of food
Swallowing Speech Provides sites for taste buds |
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Name the four main kinds of taste your taste buds can detect
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Bitter, sweet, sour, salty
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Function of teeth
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Chewing/breaking up food
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Mastication
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Chewing/breaking up food
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Number of baby teeth
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20 baby teeth
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Scientific term for baby teeth
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Deciduous teeth
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Children have all of their baby teeth during what age range?
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2-6 years old
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About what age does a child get their first tooth?
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After about six months
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About what age do children get all of their baby teeth
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age 2-3
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How many adult teeth?
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32 adult teeth
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How many adult teeth per jaw?
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16/jaw
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Cutting teeth in front
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Incisors
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How many pairs of incisors
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2 pairs
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Locations of incisors
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Central & lateral
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Canines have two other names
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Cuspids or eyeteeth
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Location of canines
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behind incisors
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function of canines
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piercing/tearing
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how many pairs of canines?
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1 pair canines
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Premolars are a.k.a.
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bicuspids
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Function of premolars
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grinding
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how many pairs of premolars
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2 pairs
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Molars are a.k.a.
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tricuspids
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Function of molars
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grinding
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How any pairs of molars
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2 pairs of molars
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Wisdom teeth are a kind of what?
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kind of molar. ("third molars"
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how many pairs wisdom teeth?
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`1 pair wisdom teeth
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Upper jaw
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Maxilla
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Lower jaw
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mandible
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Where do teeth develop?
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in maxilla or mandible
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Outer part of teeth
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enamel
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inner part of teeth
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dentin
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What cavity at core of a tooth has blood vessels?
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pulp cavity
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where is the nerve for a tooth?
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in root canal
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3 sets of salivary glands?
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Parotid glands
Submandibular glands Sublingual glands |
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How do salivary glands empty into mouth?
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empty by ducts
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Location of parotid glands
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inferior & anterior to ear
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Ducts of parotid glands
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opening in upper cheek opposite 2nd molar
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Submandibular glands location
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Floor of mouth, internal to & near angles of the mandible
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Ducts of submandibular glands
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Enter mouth at base of (under) the tongue
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Sublingual glands location
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under the tongue
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ducts of sublingual glands
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Floor of mouth (under tongue)
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Two components of saliva
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Mucus
Salivary amylase |
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Function of mucus in saliva
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Moistens & lubricates food
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_________ ____________: a digestive enzyme that breaks down starch
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Salivary amylase
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what does salivary amylase break starch down into?
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Small sugar molecules
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Three functions of salivary gland secretions
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Moisten food
Facilitate chewing and swallowing Hygeine |
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Term for swallowing
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Deglutition
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How do salivary gland secretions help with hygiene? (two parts)
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Keeps teeth & mouth clean
Reduces bacterial growth |
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Spell "Hi-gene"
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Hygiene (i before e)
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Term for throat
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pharynx
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Pharynx is what kind of tube?
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muscular tube
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what lines the pharynx?
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a mucous membrane
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what part of the digestive system is also part of the respiratory system?
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pharynx
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Three regions of pharynx
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Nasopharynx
Oropharynx Laryngopharynx |
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2 associated structures of pharynx
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Tonsils
Soft palate |
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tonsils are this kind of structure with this kind of function
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lymphatic structures with immune functions
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What structure forms the back of the roof of the mouth?
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soft palate
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Uvula:
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Soft fleshy projection hanging from the back of the soft palate
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Uvula is involved in this process
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Speech production
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What two structures close off the nasopharynx when we swallow?
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Uvula and soft palate
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Wpharynxhat structure do the uvula and soft palate close off when we swallow?
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close off nasopharynx
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Why close off the nasopharynx when we swallow?
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Prevents food from coming out of the nose
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Digestive function of pharynx
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Swallowing
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What is a rapid, involuntary reflex performed by the pharynx?
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swallowing
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Bolus
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Small, rounded portion of food formed by tongue, mixed with saliva & swallowed
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Bolus is pushed by tongue to the back of the what?
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to the back of pharynx
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Soft palate & uvula rise to block off the what?
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block off nasopharynx
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Tongue rises to block off what?
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block of the front of oropharynx
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Epiglottis covers the what?
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glottis
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Glottis
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Opening to the larynx
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Layman's term for the larynx
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Voicebox
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After the pharynx, nasopharynx, oropharynx and opening to the larynx have been closed off, where does the bolus go?
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Goes to esophagus
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What is the esophagus? (two words)
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muscular tube
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length of esophagus
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10-11 inches long
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3 functions of esophagus
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- Lubricates food with mucus
- Moves food by peristalsis to stomach - No digestion occurs in the esophagus |
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Esophagus enters the abdominal cavity through an opening in the diaphragm. What is this opening called?
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Esophageal hiatus
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Esophageal hiatus
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Opening in diaphragm through which esophagus enters abdominal cavity
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Hiatal hernia
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Weakness in the diaphragm that allows opening to become enlarged around esophagus
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what problem does a hiatal hernia cause?
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Permits stomach or other organs to protrude through it into thorax
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A hiatal hernia permits stomach or other organs to protrude through it into the thorax. What problem can this cause?
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Can allow backward movement of stomach contents into esophagus
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Gastroesophageal reflux (GERD)
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Backward movement of stomach contents into esophagus
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GERD stands for what?
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gastroesophageal reflux
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What are the two more common names for GERD?
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Heartburn
Acid indigestion |
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What is the shape of the stomach
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J-shaped organ
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Capacity of stomach
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up to 1/2 gallon
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3 muscle layers of stomach (outer → inner)
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longitudinal muscle
circular muscle oblique muscle |
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Four regions of stomach
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Cardiac
Fundic Body Pyloric |
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Cardiac region of stomach
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Where esophagus joins stomach
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Fundic region of stomach
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superior bulge under diaphragm
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Pyloric region of stomach
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Inferior region just before pyloric sphincter
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___: wrinkles/folds in the internal lining when stomach is empty
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Ruage
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When do rugae smooth out?
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When stomach is filled with food
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Two sphincters of stomach
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Lower esophageal sphincter
Pyloric sphincter |
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Sphincters
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2 muscular rings that serve as one way valves
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Two other names for lower esophageal sphincter
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Gastroesophageal sphincter
cardiac sphincter |
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Occasionally this sphincter has a transient lack of relaxation (sensation that food can't get past that point). Which sphincter?
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lower esophageal sphincter
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Location of pyloric sphincter
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Pyloric (distal) end of stomach where it joins the small intestine
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Which sphincter is general closed, with only periodic openings?
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Pyloric sphincter
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Which sphincter regulates rate of food passage into small intestine?
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pyloric sphincter
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Four functions of stomach
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Grind food to increase its surface area
Secrete digestive juices Mix food with digestive juices Temporary food storage |
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Why grind food to increase its surface area?
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To increase exposure to digestive juices
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Stomach secretions
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gastric juice
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What two components make up gastric juice?
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hydrochloric acid
pepsin |
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Origin of stomach secretions
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Microscopic gastric glands in stomach wall
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Two functions of HCl
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kills foreign organisms in food
softens connective tissue in meat |
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What is pepsin made from?
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Inactive precursor pepsinogen
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What is pepsin
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protein-digesting enzyme
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how is pepsin activated?
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by presence of food & HCl
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what quality of mucus makes it a good protective fluid?
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the fact that it's alkaline
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Point of mucus in stomach
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Protects stomach lining so gastric juice does not digest the stomach itself
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How is secretion of gastric juice regulated?
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Regulated in part by nervous & endocrine signaling
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Chyme
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Semi-liquid mixture of gastric juice/food that enters the small intest.
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Location of pancreas
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Mainly on left side of the abdomen
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Shape of pancreas
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tadpole-shaped organ
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pancreas extends from the what to the what?
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from duodenum (of small intestine) to spleen
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Endocrine functions of pancreas
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Production of hormones for regulating blood sugar levels
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What hormones does the pancreas produce to regulate blood sugar levels?
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Insulin & glucagon
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Which function of the pancreas is the digestive function?
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The exocrine function is digestive
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Exocrine function of pancreas
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Produce enyzmes for enzymatic digestion.
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Pancreas produces enzymes for enzymatic digestion of the four main nutrient classes, which are...?
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Fats,
proteins, carbohydrates, nucleic acids |
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Besides regulating blood sugar, what is the other endocrine function of the pancreas?
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Endocrine control of...
release of alkaline fluid containing sodium bicarbonate |
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Alkaline
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Basic
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Pancreas controls the release of alkaline fluid containing sodium bicarbonate via what hormone?
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Via secretin hormone
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Why does the pancreas control the release of alkaline fluid containing sodium bicarbonate?
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To neutralize acidic chyme
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Why does the pancreas work to neutralize acidic chyme?
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To protect the digestive tract lining
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Where are pancreatic digestive juices released?
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Released into a duct that joins the common bile duct &/or opens into the duodenum near the common bile duct
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Protein-digesting enzymes are released in what form?
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in inactive form
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How are inactive protein-digesting enzymes activated?
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activated by other enzymes in the small intestine
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Largest glandular organ
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Liver
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which lobe of the liver is larger?
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Larger right lobe
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The liver has two smaller medial lobes. What are they called?
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Quadrate and caudate lobes
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Location of liver
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Just inferior to the diaphragm, primarily on the right side
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color of liver
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reddish-brown color
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Vascularization of liver (3 parts)
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- Hepatic artery
- hepatic vein - hepatic portal veins |
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Function of hepatic artery
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Deliver oxygen
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Function of hepatic vein
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Returns venous blood to inferior vena cava
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Hepatic portal veins (f.)
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connects to blood vessels from the mesenteries of the small intestine
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What do hepatic portal veins bring to the liver?
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Bring blood loaded with end-products of digestion from the small intestine
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Why do the hepatic portal veins bring nutrients from the small intestine to the liver?
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So they can be processed, stored, and/or circulated to the body
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How much blood does the liver receive per minute?
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Receives 1.5 quarts of blood per minute
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Carbohydrate metabolism of liver
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glucose ← → glycogen storage
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what is the storage form of glucose in animals?
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glycogen
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Glycogen is the storage form of glucose in animals; comparable to _______ [glucose storage form] in plants
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comparable to starch
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Why does the liver convert glucose into glycogen during carbohydrate metabolism?
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So glucose is available to keep blood glucose levels in normal range
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What does the liver form?
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Forms blood plasma proteins
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What are blood plasma proteins?
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Albumin, clotting factors
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What does the liver synthesize?
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Synthesizes urea
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How does the liver synthesize urea?
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Breaks down amino acids of old proteins, makes urea
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When the liver breaks down amino acids of old proteins, it creates urea. Why?
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Because urea is a waste product of protein metabolism
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The liver releases urea into the blood. Then what happens to the urea?
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Released into blood for elimination in urine by kidneys
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What does the liver destroy?
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Destroys worn-out red blood cells
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Go into detail of liver's destruction of worn out red blood cells.
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Recycling or elimination of breakdown products
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The liver recycles or eliminates breakdown products of worn-out red blood cells. Explain this.
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The pigment bilibrubin is eliminated in bile
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Why are stools a dark color?
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Because bilirubin (pigment) is eliminated in bile
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Detoxification function of liver
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Neutralize poisonous properties of harmful substances
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What harmful substances does the liver neutralize?
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Drugs and alchohol
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What does the liver store?
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Stores certain vitamins and iron
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What is the liver's involvement in digestion?
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Lipid/fat metabolism
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Primary digestion function of liver
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Bile synthesis
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Functions of bile (2)
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Emulsifies fats
Aids in fat absorption |
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What does it mean that bile emulsifies fats?
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Acts like a detergent to break fats up into small droplets
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Why does bile act like a detergent to break fats up into small droplets?
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To increase surface area for digestive enzymes to break fats down
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The liver aids in fat absorption from what organ?
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From the small intestine
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Why is the liver involved in fat modification?
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Must modify fat into usable forms for body cells
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What is the gallbladder and where is it?
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Muscular sac inferior to liver
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What color is the gallbladder typically?
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typically yellowish green
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Function of gallbladder
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Bile storage
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Bile path (use arrows)
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Liver → gallbladder → duodenum
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What structure is the first ten inches of the small intestine?
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Duodenum
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Is there a chronic or a periodic need for bile?
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Periodic need
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Chronic
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continuous
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When chyme with fat enters the duodenum, what hormone is released from the duodenum into the blood?
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cholecystokinin (CCK)
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What does the release of cholecystokinin (CCK) into the blood cause?
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causes gallbladder contraction
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When the gallbladder contracts, what happens?
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bile is released
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Gallstones
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Semi-solid blockages of common bile duct leading to duodenum
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Gallstones consist mainly of what?
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consist mainly of cholesterol
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Three sections of small intestine
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duodenum
jejunum ileum |
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Longest portion of digestive tract
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Small intestine
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How long is the small intestine compared to the large intestine?
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10 feet vs.. 5 feet
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which intestine is smaller in diameter?
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the small intestine
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how big in diameter is the small intestine compared to the large intest.?
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1 inch vs. 2.5 inches
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How is surface area increased in the small intestine?
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Series of folds in intestinal wall
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Why increase the surface area of the small intestine?
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Important for absorptive function
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Circular folds of small intestine?
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Plicae
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What are the multiple projections extending in into the small intestine's lumen?
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Circular folds
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___________: Millions of small folds in the mucosal lining on the plicae
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Villi
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What's within each villus? (2)
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Capillary network for absorption
Lymphatic vessel (lacteal) |
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What are lacteals for?
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Lipid/fat absorption
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__________: Numerous microscopic, fingerlike projections on the surface membrane of each epithelial cell of the mucosa that makes up each villus
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Microvilli
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Where are the microvilli of the small intestine?
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on the surface membranes of each epithelial cell of the mucosa that makes up each villus
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Functions of small intestine (4)
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Peristalsis
Provides secretions from intestinal glands Most of the digestive process Most of the absorption of nutrients |
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Peristalsis
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rhythmic contractions of wall of GI tract that moves food along
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Why does the small intestine provide secretions from intestinal glands?
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to protect lining & to breakdown food
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What secretions come from intestinal glands?
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mucus, enzymes
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Where does most of the body's absorption of nutrients occur?
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Through the small intestinal walls
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Where does most of the digestive process occur?
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In the small intestine
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First 10 inches of small intestine
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Duodenum
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Middle 3-4 feet of small intestine
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Jejunum
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Last 4-5 feet of small intestine
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ileum
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Large intestine is a.k.a.
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a.k.a. colon
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How long and how wide is the large intestine?
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5 feet long, 2.5 inches wide
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Which intestine has more surface expansion: the large or small?
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Small intestine has more surface expansion
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Which intestine has no villi?
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Large intestine has no villi
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Functions of large intestine (4)
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- Mucus secretion
- Storage & ultimately elimination of undigested waste - Reabsorption of water and salts - Normal bacteria in colon |
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How does the large intestine secrete a lot of mucus?
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Lots of goblet cells
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Why does the large intestine secrete lots of mucus?
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To facilitate the movement of feces/stools
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What enzyme secretion or digestion occurs in the large intestine?
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No significant enzyme secretion or digestion occurs in the large intestine
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Normal bacteria in the colon produce 2 things.
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Vitamin K
Some B-complex vitamins |
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What happens to the large intestine during excessive antibiotic treatment?
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Excessive antibiotic treatment can kill the helpful bacteria which live there
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2 pouch-like structures off the initial portion of the large intestine
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Cecum
Vermiform appendix |
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Cecum
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Initial short pouch-like portion at junction of small & large intestine
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Ileo-cecal valve
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Separates cecum from ileum
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What does "vermiform appendix" mean?
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"worm-like"
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Vermiform appendix
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Small blind tube containing lymphoid tissue with immune function
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Location of vermiform appendix
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Near ileo-cecal junction
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Appendicitis
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Inflammation of the appendix
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Subdivisions of the large intestine (6)
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Ascending colon
Transverse colon Descending colon Sigmoid colon Rectum Anal canal & Anus |
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Ascending colon
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Extends superior along right side of abdomen
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Transverse colon
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Extends horizontal across the abdomen
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Descending colon
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Extends inferior along the left side of the abdomen
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Sigmoid colon
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Posterior S-shaped bend descending into the pelvis
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Rectum
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Relatively straight portion of the colon ending in the anal canal & anus
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Rectum function
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Used for storage of waste material prior to elimination
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What does stretching of the rectal wall lead to?
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Leads to contraction of its smooth muscle
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contraction of the rectum's smooth muscle is aided by what other contractions?
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voluntary contractions of diaphragm & abdominal muscles
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Term for elimination of feces
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Defecation
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Anal canal & anus
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Final pathway for feces out of the body
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Two division of anal sphincter muscle
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Inner anal sphincter
Outer anal sphincter |
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What kind of muscle makes up inner anal sphincter?
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Smooth, involuntary muscle
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Outer anal sphincter is made up of what kind of muscle?
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Striated muscle
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Outer anal sphincter function
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Provides voluntary control of defecation
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Site of hemorrhoids?
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anal canal & anus
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Hemorrhoids
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Enlarged veins in ano-rectal area
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Normal passage of food through stomach and small intestine takes how many hours?
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6-8 hours
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Normal passage of food through the large intestine takes about how many hours?
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About 40 hours
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How many hours does normal food passage take through the small intestine for men? For women?
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33 for men
47 for women |
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Total time from ingestion to defecation
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About 40-55 hours
(about 2 days) |
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Diarrhea
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More fluid stools due to rapid passage and thus less water reabsorption
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Food passage through the body takes how long if you have diarrhea?
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less than 1-2 days
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How do you spell "fluid stools"?
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Diarrhea
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Constipation
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More solid stools due to prolonged passage through large intestine
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What happens if stools stay in the large intestine for longer than normal?
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Excessive water reabsorption
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Why is feces retained if excessive water is reabsorbed from it?
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Because of reduced stimulation of bowel emptying reflex
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How long does passage of food through the body take if someone is constipated?
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more than 3-4 days
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