Digestive Systems (Part 1) Flashcards
What kind of diet can heterotrophs have?
- herbivores
- carnivores
- omnivores
Do sponges have a digestive system?
no
How do sponges do digestion?
intracellular digestion via endocytosis
How do all non-sponges do digestion?
extracellularly, in a digestive cavity
Do Cnidarians (and some flatworms) have a digestive system?
incomplete digestive tract and gastrovascular cavity
What is a complete digestive tract?
separate mouth and anus connected by a continuous digestive tube
What kind of digestive system do nematodes have?
complete, tube within a tube
What kind of digestive system do vertebrates have?
complete, beyond a simple tube
What locates food in vertebrate digestive systems?
sensory organs
What makes up the oral cavity?
mouth and pharynx
What is the function of the oral cavity?
entry, mechanical and initial chemical digestion
Are teeth always present in an oral cavity?
may or may not be present
What makes up the tubular gastrointestinal tract?
- esophagus
- stomach
- small intestine
- large intestine
- cloaca or rectum
Function of esophagus?
delivers food to stomach
Function of stomach?
mechanical, chemical, minor amount of absorption
Function of small intestine?
chemical digestion, absorption
Function of large intestine?
concentration of wastes
Function of cloaca or rectum?
waste storage
What is the function of teeth?
chewing/mastication
What does tooth shape match?
diet
Do birds have teeth?
no
How do birds do mastication?
gizzard using ingested pebbles (break up seeds)
What do some birds do with prey?
consume prey whole
What is the function of the crop?
storage, NO digestion
What is the esophagus?
a muscular tube that connects mouth to stomach
How do esophagus know to move food down?
presence of food bolus stimulates movement towards stomach, peristalsis
What does peristalsis mean?
muscles move food down
Does digestion or absorption occur in the esophagus?
no
What is the esophagus lined with?
muscle tissue
What kind of muscle makes up the esophagus?
1st part (1/3) is skeletal and 2/3 is smooth
Can food bolus be removed from skeletal muscle part of esophagus?
yes, we can control it
Can food bolus be removed from smooth muscles part of esophagus?
no, not unless vomit or forcibly removed
What prevents food from leaving the stomach and reentering the esophagus?
sphincter at esophageal-gastric
What kind of surface does the stomach have?
convoluted, folds
How many chambers does the stomach have?
varies by species
Why is the stomach surface folded?
greater surface area for digestion; also so it can stretch and increase volume
What are gastric juices made of?
2 kinds of secretory cells
What are the 2 kinds of secretory cells?
parietal and chief
What do parietal cells secrete?
HCl and intrinsic factor
What is the function of intrinsic factor?
vitamin B12 absorption
What is the function of chief cells?
secrete pepsinogen
What is pepsinogen?
inactive form of pepsin
What is the stomach?
a mixing chamber
What is not significantly digested in the stomach?
carbohydrates and fats
What does the stomach produce?
chime
What is chime?
slurry of partially digested food
How many sphincters does the stomach have?
2
What pH does the stomach have?
low
Why does the stomach have a low pH?
denature food proteins
What sphincters does the stomach have?
- esophageal
- pyloric
What are the parts of the small intestine?
- duodenum
- jejunum
- ileum
What happens in the small intestine?
chemical digestion (final) and absorption
What type of cells are in the small intestine?
mucosal cells
what do mucosal cells have?
villi, microvilli
What is the significance of mucosal cells having villi?
increase surface area
What is the function of the duodenum?
final chemical digestion
What is the function of the jejunum?
majority of absorption of nutrients
What is the function of the ileum?
picks up what didn’t get absorbed
What is the largest internal organ in humans?
liver
What does the liver produce?
bile
What are the types of bile?
bile products and bile salts
What are bile pigments?
waste products
What are bile salts for?
emulsification of fats
What does the live receive?
products of digestion (the first to recieve)
What does the liver detoxify?
metabolites
What is the function of the gallbladder?
stores and concentrates bile
When does the gallbladder secrete bile?
when food present in duodenum
What is the gallbladder connected to?
liver by the bile duct
Do all animals have a gallbladder?
no
What animals do not have a gallbladder?
- horses
- deer
- rats
- some birds
- lampreys
- laminoids
- all invertebrates
What types of functions does the pancreas have?
both endocrine and exocrine
What does endocrine involve?
hormones
What does exocrine involve?
digestive
What does the pancreas produce?
digestive enzymes
What does the pancreas secrete?
bicarbonate
What digestive enzymes does the pancreas produce?
trypsin, chymotrypsin, pancreatic amylase, and lipase
What does lipase do?
break down lipids
What does pancreatic amylase do?
digest carbohydrates
What does trypsin do?
digests proteins
Do all vertebrates have a pancreas?
yes
What is the pancreas connected to?
pancreatic duct to duodenum
What are the parts of the large intestine or colon?
ascending (up), transverse (across), descending (down), sigmoid
What is the function of the large intesine?
4% absorption of water, remaining electrolytes, and vitamin K; mainly concentration of waste
Where are the cecum and appendix?
at junction of ileum-colon
What are at the terminus of the digestive tract?
rectum and anus, (and cloaca in most)
What is the function of the rectum?
waste storage until defecation
What is the function of the anus?
exit point with inner voluntary sphincter and outer voluntary sphincter
Do most mammals have a rectum?
yes
What mammals do not have a rectum?
monotreme: echidna and platypus
Most ______ have what common cavity?
vertebrates; cloaca
What is the function of the cloaca?
single opening for digestive, urinary, reproductive products
Does digestion happen in the large intestine?
no