Part 4.1: Digestion

Question 1

Methods of obtaining food (7)

Answer 1

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

Question 2

vampire bat feeding mechanism

Answer 2

fluid feeder. makes knick in flesh with teeth. saliva contains sensation reducing analgesic and anticoagulant. Pees out all the water almost immediately.

Question 3

4 key functions of digestive systems

Answer 3

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)

Question 4

secretory functions of digestive systems borrow fluid from the ____ and resorbs them in the ____ ____

Answer 4

Plasma and resorbs the fluid in the large intestine

Question 5

ruminnant stomachs

Answer 5

chambered stomachs

Question 6

ingestion organs

Answer 6

mouth and pharynx

Question 7

absorption and assimilation tends to happen in the

Answer 7

hindgut (small and large intestines)

Question 8

vertebrate digestive tract outline

Answer 8

1) oral cavity
2) foregut/crop/esophagus
3) stomach (midgut)
4) small intesine
5) large intestine
6) excretory region (anus, rectum)

Question 9

purpose of oral cavity

Answer 9

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)

Question 10

teeth have been modified for social jobs (ex/ territorial defense) in addition to aiding in mechanical digestion. what is this called?

Answer 10

exaptation

Question 11

digestion starts in the ___. How so? which structures in this region help out with the beginning of digestion?

Answer 11

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.

Question 12

function of salivary glands in the oral cavity. Enzymes involved?

Answer 12

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.

Question 13

3 main salivary glans in humans

Answer 13

1) parotid 2)sublingual 3) submandibular.

Question 14

salivary stimulation can be ___ or ____, such as mouth watering.

Answer 14

unconditioned or conditioned, such as mouth watering. Sympathetic and parasympathetic also both stimulate salivation.

Question 15

salivary center is located in ___

Answer 15

medulla.

Question 16

simple reflex for unconditioned salivation

Answer 16

1) pressure receptors and chemoreceptors in mouth 2) salivary center in medulla activate autonomic nerves 3) autonomic nerves activate salivary glands and cause secretion.

Question 17

Conditioned salivation such as to associations activates the ____ ____, which has descending inputs to the __ ___ in the medulla.

Answer 17

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)

Question 18

T/F: salivary glands is innervated by the sympathetic and parasympathetic nerves, which trigger the SAME response

Answer 18

TRUE. both nervous systems stimulated salivation.

Question 19

why do you get dry mouth when you are nervous?

Answer 19

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

Question 20

Purpose of pharynx

Answer 20

it conducts the all or none reflex of swallowing (DEGLUITION).

Question 21

Purpose of uvula and epiglottis.

Answer 21

direct bolus of food to the esophagus and prevent it from getting into airawy

Question 22

the ____ connect oral cavity to esophagus

Answer 22

the pharynx

Question 23

during the swallowing process, the swallowing center in the medulla inhibits the ___ ___ in the brain stem

Answer 23

respiratory center, so that you don’t breathe and swallow at the same time

Question 24

the ____ prevents food from entering nasal passage

Answer 24

uvula

Question 25

tight apposition of vocal folds across the __ prevents food from entering the airways

Answer 25

glottis.

Question 26

the esophagus contains muscular ____ on each end to prevent the bolus from moving in the wrong direction. how many does the esophagus have?

Answer 26

sphincters: 1) pharyngoesophogeal sphincter: keeps air from entering stomach. 2)gastroesophageal sphincter: prevents reflex. failure of this sphincter causes heart burn

Question 27

peristalsis

Answer 27

waves of smooth muscle contraction

Question 28

what triggers more peristalsis in the esophagus?

Answer 28

STRETCHING

1) bolus stimulates stretch receptors
2) stronger wave of peristalsis
3) stimulates salivary reflex and mucous production for adequate lubrication.

Question 29

Purpose of mucous that is secreted in the esophagus

Answer 29

PROTECTION. Not actually digestive, unlike in the saliva or the stomach. protects against abrasion

Question 30

Modification of the esophagus in bugs and some birds

Answer 30

the crop.

Question 31

purpose of the crop. Why is it super important for birds?

Answer 31

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.

Question 32

in insects, the ___ lies behind the crop, which aids in more digestion

Answer 32

proventriculus. If the proventriculus is full, motility of the crop is inhibited. (NEGATIVE FEEDBACK)

Question 33

exaptations of the crop (2)

Answer 33

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

Question 34

Oultine the flow chard from gross energy to net energy

Answer 34

Question 35

How are vitamins typically characterized?

Answer 35

by solubility: fat soluble –> vit A, D, E K

water soluble –> B and C

Question 36

Minerals are metallic elements that participate in ___ ___

Answer 36

protein structure and function

Question 37

typical use of a vitamin

Answer 37

many vitamins participate in catalysis as cofactors for enzymes

Question 38

how many essentail amino acids are there

Answer 38

8

Question 39

What are the essential fatty acids?

Answer 39

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