DIGESTIVE SYSTEM UNIT TEST REVIEW Flashcards
Overall function of the digestive system
The mechanical and chemical breakdown of food and the absorption of nutrients by cells
What does the digestive system consist of
Alimentary canal (9 meters from mouth to anus) and accessory organs
Pathway of digestion
Mouth, pharynx, esophagus, stomach, small intestine, large intestine, anal canal
Alimentary canal
The whole passage along which food passes through the body from mouth to anus during digestion.
Structure of the wall of alimentary canal (4):
- Mucosa
- Submucosa
- Muscular layer
- Serosa
Mucosa
Mucous membrane. Protects tissues, and carries out absorption
Submucosa
Contains glands, blood vessels, lymphatic vessels, and nerves
Muscular layer
Smooth muscle tissue, circular and longitudinal fibers, pushes food
Serosa
Serosa layer. Visceral peritoneum, outer covering of the tube, moistens and lubricates structures
Mixing movements
Rhythmic contractions that mix food from digestive juices
Propelling movements
Rings of muscles contract and relax to push food down the canal called PERISTALSIS
PeristalsiS
Series of muscle contractions
Mouth
Begins digestion by reducing size of particles (chewing) and mixing with saliva
Tongue
Moves food during chewing, connects to the floor of mouth and contains papillae (taste buds)
Palate
Forms roof of oral cavity (hard and soft), uvula at back of mouth
Palatine tonsils
Back of the mouth/throat, they protect against infections
Teeth
Primary vs secondary teeth; incisors, cuspids, bicuspids (premolars), molars
Anatomy of a tooth (4):
- Crown
- Root
- Enamel
- Dentin
Crown (TOOTH)
Projects above gums
Root (TOOTH)
Anchored to alveolar process of jaw
Enamel (TOOTH)
Made of calcium salts, hardest substance in body
Dentin (TOOTH)
Similar to bone, surrounds tooth’s central cavity
Significance of blood vessels and nerves to tooth
They extend through the tooth through the root canal
Production of salivary amylase
Serous cells
What can salivary amylase do
Splits starch or glycogen + water into maltose
Production of mucous
Mucous cells produce mucus which are used for lubrication during swallowing
3 different salivary glands:
- Parotid glands
- Submandibular glands
- Sublingual glands
Pharynx
Tube located from behind the nose to the top of trachea and esophagus. Region where food and air passes
Esophagus
Hollow muscular tube that carries food and liquid from your throat to your stomach. It penetrates the diaphragm at the esophageal hiatus
Cardiac sphincter
Located above stomach. It prevents food and chemicals from moving up stomach
3 sets of stomach muscles
Longitudinal, oblique, circular
4 main parts of the stomach:
- Cardiac
- Fundic
- Body
- Pyloric
Cardiac (STOMACH)
Esophageal opening, cardiac sphincter
Fundic (STOMACH)
Temporary storage area, lies slightly above cardiac region
Body (STOMACH)
Central area of stomach
Pyloric (STOMACH)
Pyloric sphincter, controls emptying of the stomach into the small intestine
Lining of a stomach
Mucous membrane with small openings called gastric pits that contain gastric glands
What do gastric glands release
Gastric juice
What is gastric juice composed of
Pepsinogen + HCl = Pepsin
Pepsin
Breaks down proteins and water in peptides
Chyme
Paste of food molecules after it’s been broken down by the movement of stomach and gastric juices. It is released from pyloric sphincter valve into the duodenum
Rugae
Folds within the stomach, and increases surface area
Pancreas
Has exocrine functions and contains pancreatic glands that secrete pancreatic juice through the pancreatic duct. It also has endocrine functions that can produce and secrete hormones insulin and glucagon
Acronym for pancreatic juice
PLANTS
What is contained in pancreatic juice:
- Pancreas
- Lipase; breaks down fat and water into fatty acids and glycerol
- Amylase; breaks down starch and water in maltose
- Nuclease; breaks down nucleic acids and water into nucleotides
- Trypsin; breaks down proteins and water into peptides
- Sodium bicarbonate; acts as a buffer to neutralize the acid chyme to become a pH of 8-9
Where is insulin made
Beta cells
Where is glucagon made
Alpha cells
Insulin
Secreted when body has high sugar levels in blood
3 things insulin causes:
- Excess glucose stored as glycogen in liver
- Excess glucose converted and stored as adipose tissue
- Body cells uptake glucose and use for energy
Glucagon
Secreted when body has low sugar levels in blood
3 things glucagon causes:
- Glycogen converted back to glucose and put back into blood
- Body cells stop the uptake of glucose
- Adipose tissue can be converted back to glucose
Characteristic of the liver
Has large right and small left lobe
Biliary system
System of organs including the liver, gallbladder, and pancreas that are associated in the function to produce, store, secrete and transport bile
Hepatic portal vein
Delivers blood to the liver
7 functions of the biliary system:
- Maintains blood sugar. Glucose is stored as glycogen or glycogen can be converted to glucose
- Creates/secretes bile
- Deamination (removal) of excess amino acids
- Stores iron and vitamin
- Destroys damaged red blood cells
- Detoxifies and removes toxic substances
- Creates plasma proteins (Fibrinogen, blood clotting)
Bile
Yellowish-green liquid secreted from hepatic cells. Aids in digestion by breaking down fat globules into smaller droplets
Jaundice condition
Bile pigments build up in blood and skin becomes green
How is the common bile duct formed
When hepatic duct joins the cystic duct
Where is bile made
Liver but stored in gall bladder
Small intestine characteristic
Tubular organ that extends from the pyloric sphincter. It has many loops and coils and fills most of the abdominal cavity
Small intestine overall function
Secrete intestinal juice from intestinal glands. Intestinal juice used to break down food and carry nutrients to blood for absorption using villi
Where does the small intestine receive its secretions
Pancreas and the liver. It completes digestion of nutrients and chyme
First part of the small intestine
Duodenum
Second part of the small intestine and how long
Jejunum 2.2m
Third part of the small intestine and how long
Ileum 3.3m
Mesentery
Supports the coils of small intestine and contains blood vessels to carry nutrients
Greater omentum
Peritoneum membrane that drapes like an apron over parts of the system
Intestinal villi
Increases surface area for absorption
Intestinal glands
Release intestinal juice
Acronym for intestinal juice
My penis needs some love
What is contained in intestinal juice:
- Maltase; breaks down maltose + water into glucose and glucose
- Peptidase; breaks down peptides + water in amino acids
- Nucleosidase; breaks down nucleotides and water in phosphate group, pentose sugar and nitrogen base
- Sucrase; breaks down sucrose + water into glucose and fructose
- Lactase; breaks down lactose + water into glucose and galactose
Nutrients that can be absorbed in the villi (9):
- Glucose
- Amino acids
- Phosphate
- Pentose sugar
- Nitrogen base
- Vitamins
- Minerals
- Fatty acids
- Glycerol
Mode of transport for the nutrients that can be absorbed in villi
All are active transport except for fatty acids and glycerol which are through diffusion
Where in the villus are the nutrients absorbed
All are in the capillary net except for fatty acids and glycerol which are absorbed in the lacteal
Why are fatty acids and glycerol absorbed in the lacteal
Cannot be transported in the capillaries since fatty acids and glycerol will block the blood flow
Why is the large intestine called the large intestine
Has a larger diameter than the small intestine
Beginning of the large intestine
Cecum. It is pouchlike and the closed end is called the appendix
Colon
Ascending/transverse/descending/sigmoid
Rectum
Stores waste before expelled from body
Anus
Muscular sphincter which controls exit of waste
Function of large intestine
Absorption of water and electrolytes
What does large intestine contain and why
E.Coli to produce amino acids, vitamin K, and growth factors and can help digestion process
Mass movements large intestine
Large portions of colon contract to move materials through it using defecations.
Defecations
Process where feces stored in the rectum leave out the anus
Some disorders of the digestive system (6):
- Diarrhea
- Stomach ulcers
- Hepatitis
- Gallstones
- Celiac disease
- Crohns disease
Besides undigested food, what do feces contain
Bile pigment, bacteria
Physical/mechanical digestion
Chewing/movement of food throughout digestive tract
Chemical digestion
Enzymes and digestive juices breakdown food to be absorbed in body
Bolus
Chewed ball of food ready for swallowing
When you swallow, why does food not go down trachea
Epiglottis covers opening into trachea
When you swallow, why does food not go up nasopharynx into nose
Uvula covers nasopharynx opening
Tube connecting pharynx to stomach
Esophagus
Peristalsis process
Wave like rhythmic contractions pushes food along body
pH of food in stomach
2-4
Chyme
Semisolid food in stomach
How long does food usually stay in stomach
2-6 hours
How are ulcers caused
When HCL penetrates mucus lining of stomach, you get autodigestion of the wall
Where is bile produced
Liver
Where is bile stored
Gallbladder
How does bile get secreted into duodenum
Common bile duct
Hormone that stimulates release of bile
CCK (Cholecystokinin)
What food stimulates production of CCK
Fat
How does CCK reach gallbladder
Bloodstream through endocrine gland
Where does pancreatic juice perform function
Duodenum
How does pancreatic juice reach duodenum
Pancreatic duct through exocrine gland
Function of sodium bicarbonate in pancreatic juice
Neutralizes acidity of chyme from stomach
Hormone controlling secretion of pancreatic juice
Secretin
Where is secretin produced
Duodenal wall
What stimulates production of secretin
HCI present in chyme
Absorption
Process of taking nutrients from digestive system into the blood to be used for body
How is the small intestine specialized for absorption
Villi which has an increase in surface area beneficial for absorption
Where does absorption occur
Across wall of each villus in small intestine
