21. Mammalian Digestive System Flashcards
what is the strucutre (2) of the gastrointestinal system (GI)
it consists of the GI tract
associated glandular organs to produce secretions in the GI tract
what are three functions of the GI tract?
- transportation of food
- digestoin - reduce food particle to molecules that can be absorbed by the blood
- absorbtion - allows nutrients to pass through membranes
- synthesis of vitamins
- excretion - elimation of waste produce
- immune function
what are the four stages of food processing?
- ingestion
- digestion
- absorbtion
- elimination
how does the GI system have a large surface area? (5 points)
its very long - 6 metres in humans
walls are folded to increase surface area
there are villi on the walls
the villi have microvilli to have maximum surface area
epithelial cells only one cell thick for short diffusion distance
what are two adaptations of the mouth (in different species) that allow for functional use of the mouth
prehension - to bring the food to the mouth (using arms, claws, mouth, teeth etc)
chewing - to crush food - increase surface area and release of chemical enymes
what is the difference in carnivoures and herbivous in terms of what the function of their mouth does to the food they consume?
carnivours only need to reduce the size of the particle
herbviours must continuously chew to break down the cellulose
what are dental adaptations herbviours have for mastication of food (chewing food) (4 points)
- horny pad replaces upper incisor and canines
- jaws move verically and laterally (to grind food more effiencently)
- teeth have open roots to continuosuly grow
- diastema - a gap to seperate newly nibbled food from that being chewed at the back
what are intestinal adaptations of herbviours to masticate their food? one point
they have a long gut because digestion of plants is difficult
what is the problem with cellulose and how is it digested in herbviours? (two problesm and two slutions)
problem: mammals dont produce the enzymes required to break it down
cellulose is digested by cellulase - secreted by symbiotic micro-organisms
problem: the micro-organisms need to be protected from the aciditiy of the stomach
there is a seperate compartment in the digestive tract to house these micro organisms
give five steps of a ruminants digestive system
- consumtion of cellulose based feed (eg grass)
- partially chewed, stored in the rumen where micro organisms break it down
- few hours later the ruminant reguritates food to the mouth, thourghly chews it then re swallows it
- then the ‘cud’ enters the omasum and abomasum (true stomach)
give four funky facts on the ruminants mouth
- theres no amylase in saliva (chemical digestion)
- prehensile tounge
- lots of bicarbinate in saliva
- teeth can be used to determine age
how do non-ruminant herbivours digest cellulose?
they have a large caecum and appendix to accomadate micro-organisms for digestion of cellulose
what are three advantages and three disadvantages of utilising cellulose?
advantages:
- abundant in the enviornment
- easily obtained (dont ‘hunt’ for plants
- plant cell walls and fibre high in energy
disadvantages:
- indigestible by mammalian digestive enymes
- cellulase is found only in bacteria
- low in nutrients
what type of mammals has foregut fermentation and what are three features of this way of fermentation?
ruminants are foregut fermentors.
- more effiecent fermination per unit volume of food
- slower digestive process
- animal can starve with a full belly
- size restricted
- wild animals can eat and run
what type of mammal has hindgut fermination and what are two features of it?
non-ruminant mammals have hindgut fermination
- more effiecent relative to time
- faster turnover of food
3.
what are five dental adaptation of a carnivours jaw?
- incisors are sharp
- canines are long and pointed
- large carnassial teeth for crushing bones
- teath of upper jaw overlap to slice meat
- jaw muscels highly developed
- large verticle movement of jaws to open wide
