Part 4.1: Digestion Flashcards
Methods of obtaining food (7)
1) direct absorption 2) phagocytosis (leukocytes) 3) suction feeding (rotifers) 4) filter feeding 5) fluid feeding (mosquitos, vampire bats) ex/ nectar bat contains very long tongue to feed on nectar in flowers with long nectar tubes. 6) herbivory 7) carnivory
vampire bat feeding mechanism
fluid feeder. makes knick in flesh with teeth. saliva contains sensation reducing analgesic and anticoagulant. Pees out all the water almost immediately.
4 key functions of digestive systems
1) motility: food must move through digestive tract, food must be homogenized by other muscle groups (mechanical digestion) 2) secretion: fluid burrowed from the plasma and resorbed 3) digestion: hydrolysis of structurally complex molecules (chemical digestion) 4) absorption: small moleucels transfferred from digestive system into the hemolymph (blood)
secretory functions of digestive systems borrow fluid from the ____ and resorbs them in the ____ ____
Plasma and resorbs the fluid in the large intestine
ruminnant stomachs
chambered stomachs
ingestion organs
mouth and pharynx
absorption and assimilation tends to happen in the
hindgut (small and large intestines)
vertebrate digestive tract outline
1) oral cavity
2) foregut/crop/esophagus
3) stomach (midgut)
4) small intesine
5) large intestine
6) excretory region (anus, rectum)
purpose of oral cavity
1) ingestion and procurement of food,
2) teeth (diverse types) for rudimentary mechanical digestion, or beaks (birds don’t have teeth), spider chelicerae. mouthparts are modified in many ways.
- fangs may be used for digestion (via venum) or procurement purposes
3) tongue ( manipulate and even capture food, for sensory purposes such as olfaction, secretes anti-microbial peptides)
teeth have been modified for social jobs (ex/ territorial defense) in addition to aiding in mechanical digestion. what is this called?
exaptation
digestion starts in the ___. How so? which structures in this region help out with the beginning of digestion?
mouth.
1) mechanical breakdown : herbivores, omnivores, some carnivores
2) fangs: deliver (oral secretion adaptation) venom. Can immobilize prey and has some digestive features.
3) tongue: can manipulate and capture food (ex/ nectar bats, frogs), olfaction and chemosensation(taste) purposes, anti-microbial peptides to prevent infection.
function of salivary glands in the oral cavity. Enzymes involved?
secretes fluid and mucous to help dissolve and lubricate ingested material so it can slide down the digestive tract. also helps with TASTE.
Enzymes secreted in saliva:
1) amylase: basic carb/starch digestion.
2) lysozymes
3) other enzymes such as in snake venom. ex/ swiftlet birds secrete salivary enzymes that can adhere things together and helps create a nest.
3 main salivary glans in humans
1) parotid 2)sublingual 3) submandibular.
salivary stimulation can be ___ or ____, such as mouth watering.
unconditioned or conditioned, such as mouth watering. Sympathetic and parasympathetic also both stimulate salivation.
salivary center is located in ___
medulla.
simple reflex for unconditioned salivation
1) pressure receptors and chemoreceptors in mouth 2) salivary center in medulla activate autonomic nerves 3) autonomic nerves activate salivary glands and cause secretion.
Conditioned salivation such as to associations activates the ____ ____, which has descending inputs to the __ ___ in the medulla.
Conditioned salivation such as to associations activates the CEREBRAL CORTEX, which has descending inputs to the SALIVARY CENTER in the medulla, which leads to the same response as the unconditioned response (salivation)
T/F: salivary glands is innervated by the sympathetic and parasympathetic nerves, which trigger the SAME response
TRUE. both nervous systems stimulated salivation.
why do you get dry mouth when you are nervous?
sympathetic activation. actually is producing a lot of saliva but the composition is different than digestive saliva. Contains lots of anti-microbial peptides and less mucous
Purpose of pharynx
it conducts the all or none reflex of swallowing (DEGLUITION).
Purpose of uvula and epiglottis.
direct bolus of food to the esophagus and prevent it from getting into airawy
the ____ connect oral cavity to esophagus
the pharynx
during the swallowing process, the swallowing center in the medulla inhibits the ___ ___ in the brain stem
respiratory center, so that you don’t breathe and swallow at the same time
the ____ prevents food from entering nasal passage
uvula
tight apposition of vocal folds across the __ prevents food from entering the airways
glottis.
the esophagus contains muscular ____ on each end to prevent the bolus from moving in the wrong direction. how many does the esophagus have?
sphincters: 1) pharyngoesophogeal sphincter: keeps air from entering stomach. 2)gastroesophageal sphincter: prevents reflex. failure of this sphincter causes heart burn
peristalsis
waves of smooth muscle contraction
what triggers more peristalsis in the esophagus?
STRETCHING
1) bolus stimulates stretch receptors
2) stronger wave of peristalsis
3) stimulates salivary reflex and mucous production for adequate lubrication.
Purpose of mucous that is secreted in the esophagus
PROTECTION. Not actually digestive, unlike in the saliva or the stomach. protects against abrasion
Modification of the esophagus in bugs and some birds
the crop.
purpose of the crop. Why is it super important for birds?
aids in storage of food. kind of like a stomach but with no digestive function (no glandular portions) very important for birds because digestion takes a long time. foraging efficiency is increased with more storage space. Also good for sea birds which need to venture far away in the ocean to find food.
in insects, the ___ lies behind the crop, which aids in more digestion
proventriculus. If the proventriculus is full, motility of the crop is inhibited. (NEGATIVE FEEDBACK)
exaptations of the crop (2)
1) bird lactation–> crop milk epithelial cells responds to prolactin hormone in some birds to synthesize lipids and are then regurgitated with food to supplement the diet of chicks. same hormone that triggers lactation in mammals
2) fermentation vat in some species (stink birds) for cellulose digestion and helps detoxify poisonous plants
Oultine the flow chard from gross energy to net energy
How are vitamins typically characterized?
by solubility: fat soluble –> vit A, D, E K
water soluble –> B and C
Minerals are metallic elements that participate in ___ ___
protein structure and function
typical use of a vitamin
many vitamins participate in catalysis as cofactors for enzymes
how many essentail amino acids are there
8
What are the essential fatty acids?
omega 3 ( ingested as linolenic acid) or omega 6 FA ( ingested as linoleic acid). the rest can be made from acetyl coA and other enzymes
