Digestive System Flashcards
Sections of alimentary canal (5)
Oral Cavity Esophagus Stomach Small Intestine Large Intestine
Accessory organs of digestive system
- Salivary glands
- Pancreas
- Liver
- Teeth & tongue (not organs)
- Gallbladder
Salivary glands
Secrete saliva. Saliva is made of mucus, serous fluids (salivary amylase), and lysozyme & antibodies.
Pancreas
Exocrine function: secretes digestive enzymes
Mechanical digestion
Physical changes that occur from chewing, stomach churning, and segmentation by small intestine
Four major types of teeth
Incisors (2/quadrant)
Canine (1/quadrant)
Premolars/bicuspids (2/quadrant)
Molars (3/quadrant)
Chemical digestion
Hydrolisis reactions where enzymes break large food molecules down to their building blocks
Transverse section of alimentary canal, layers
Serosa Muscularis externa - Longitudinal fibers - Circular fibers Submucosa Mucosa
Esophagus
Conducts food from pharynx to stomach, ~10 inches
Gastric gland
- Situated in gastric pits
- Secretes gastric juice
Parietal cells
Excrete HCl (hydrochloric acid)
Chief cells
Excrete enzyme pepsinogen, which changes to its active form pepsin with the addition of HCl
Small Intestine
- Duodenum (4%) (mostly nutrient absorption)
- Jejunum (40%)
- Ileum (56%) (water absorption and mucous production, lots of goblet cells)
Segments of large intestine (7)
- Cecum
- Ascending colon
- Transverse colon
- Descending colon
- Sigmoid colon
- Rectum
- Anus
Primary functions of large intestine
- Dry out indigestible food residue by absorbing water
- Eliminate these residues from body as feces
- no villi
Gastrin
- Produced by enteroendocrine cells
- Stimulates release of gastric juice
- Stimulates stomach emptying
Secretin
- Causes the liver to increase bile output (bile is necessary for fat absorption)
Cholecystokinin (CCK)
- Causes the gallbladder to release stored bile
Brush border enzymes
- Break down double sugars into simple sugars
- Complete some protein digestion
Pepsin
- Active protein-digesting enzyme
- In the protease category
Rennin
- Digests milk protein in infants
Pancreatic amylase
- Digestion of starch
Lipase
- Fat digestion
Nuclease
- Nucleic acid digestion
Trypsin, chymotrypsin, carboxpeptidase
- Protein digestion
Carbohydrates
- Derived mainly from plants, also lactose in milk and glycogens in meats
- End products are galactose, glucose, fructose
- Contain cellulose which act as fiber and aids digestion
Lipids/fats
- Saturated fats from animal products
- Unsaturated fats from nuts, seeds, veggie oils
- End products are fatty acids and glycerol
- Cholesterol from egg yolk, meats, milk products
- Fats build myelin sheaths and cell membranes
Proteins
- End product: amino acids
- Complete proteins contain all essential amino acids
- Most from animal, some incomplete from legumes and beans
- Uses are functional and structural proteins (or ATP if other materials are lacking or there is excess)
Vitamins
- Found in all major food groups
- Most are coenzymes (act with an enzyme to accomplish a particular type of catalysis)
Anabolism
- Larger molecules or structures are built from smaller ones
Catabolism
- Substances are broken down to simpler substances
Liver (digestion)
- Detoxifies drugs and alcohol
- Degrades hormones
- Produces cholesterol, blood proteins
- Manufactures bile
Glycogenesis (liver)
- Glycogen formation
- Glucose molecules are converted to glycogen, glycogen is stored in the liver
Glycogenolysis (liver)
- Glucose splitting
- Glucose is released from the liver after conversion from glycogen
Gluconeogenesis (liver)
- Formation of new sugar
- Glucose is produced from fats and proteins
Carbohydrates in cell metabolism
- ATP
- Excess stored as glycogen or fat
- Can be broken down by liver for ATP formation or broken down to glucose and released in blood
Fats in cell metabolism
- ATP synthesis by liver, after being broken down to acetic acid
- Build myelin sheaths and cell membranes
Proteins in cell metabolism
- Broken down to amino acids
- Amine groups are removed from proteins as ammonia
- Liver converts harmful ammonia to urea
Factors that influence metabolic rate
- Surface area: smaller body has higher basic metabolic rate (BMR)
- Gender: males have higher BMR
- Age: children and adolescents have higher BMR
- Amount of thyroxin: more means higher metabolic rate
Swallowing
- Buccal phase: voluntary, forces bolos (chewed up food) into pharynx
- Pharyngeal-esophageal phase: involuntary, transports down pharynx and esophagus, everything moves in unison, longitudinal then circular muscles contract
Pyloric sphincter
- Stomach enters small intestine
Cellular respiration
- Oxygen-using events take place within the cell to create ATP from ADP
- Glycolysis: energizes a glucose molecule
- Krebs cycle: produces all carbon dioxide and water from cell respiration
Cholesterol
- Not used for ATP
- Structural basis for steroid hormones, building block for plasma membranes
- Most is not eaten, but produced in the liver
