Digestive System Flashcards
1
Q
What is the function of the digestive system?
A
To break down food into consumable parts and extract valuable nutrients and water. Also to allow mass processing of low nutrient value food.
2
Q
The digestion system is the creation and removal of?
A
Waste products
3
Q
What compounds does the digestion system deal with?
A
Toxic compounds
4
Q
What is the oral (buccal) cavity?
A
The mouth
5
Q
The roof of the buccal cavity is called?
A
The palate
6
Q
What are the different types of palates?
A
Hard and soft palate
7
Q
What do palatal folds form?
A
A second horizontal shelf that separates the nose and the mouth this is called the secondary palate
8
Q
The hard palate is made of?
A
Bony pre-maxilla and maxilla bones
9
Q
Do mammals have a soft or hard palate?
A
They have both
10
Q
In mammals, where is the soft palate?
A
It hangs from the bony hard palate
11
Q
What is pushed further back in the buccal cavity?
A
Internal nerves
12
Q
What is the uvula?
A
It is the thing that hangs down the back of the throat
13
Q
What does the soft palate allow?
A
Allows you to feel and allows gag reflex so that people don’t choke
14
Q
What does the secondary palate consist of?
A
The hard and soft palate
15
Q
Where does the primary palate form?
A
Anterior to the incisive foramen
16
Q
In tetrapods, how do nasal passages reach the mouth?
A
Through openings in the primary palate
17
Q
Where is the hard palate and soft palate in the mouth?
A
Hard palate is at the front and soft palate is at the back
18
Q
What is the function of the tongue in humans?
A
To move food around mouth and push food to the back of the mouth for swallowing
19
Q
In what animals is the tongue immobile?
A
Jawed fishes, turtles, crocodile and some birds
20
Q
What is the tongue like in snakes and nectar feeding bats?
A
Flexible and mobile
21
Q
What do the modifications in the frogs tongue allow?
A
Allows the tongue to protrude quickly and be drawn back, glands to create sticky fluid
22
Q
Labial is…
A
Near the lips
23
Q
Palatal is…
A
Near the palate, internasal and submaxillary
24
Q
Why can glands be modified?
A
To release venom,
Used for saliva for lubrication,
To seduce prey
25
What is the nasopharynx used for?
Air
26
What is the oropharynx used for?
Food
27
The pharynx opens for?
Opening for Eustacian tube which opens to the oesophagus which then opens to the larynx covered by epiglottis
Eustacian tube -> Oesophagus -> Larynx
28
What is swallowing?
When the bolus of food is pushed from the buccal cavity to the oesophagus and then to the stomach
Bolus -> Buccal Cavity -> Oesophagus -> Stomach
29
How do many vertebrates 'bolt' their food?
By swallowing it whole and then stretching the oesophagus
30
How do snakes eat their prey?
They take prey whole and move their jaws left and right to 'walk' the food down their throat and then muscular contractions squeeze the food down the oesophagus.
31
Swallowing may take time in a snake, so how does the snake cope with this?
The snakes trachea slips down and forwards beneath the prey item to keep their airway open whilst they swallow
32
What is the oesophagus?
A muscular tube that connects the pharynx to the stomach
33
Why does the oesophagus stretch?
To accommodate bolus of food
34
Why do some species have stratified epithelium and keratinised epithelium?
To allow ingestion of abrasive foodstuffs
35
Can the oesophagus be a site of storage?
Yes, when large amounts of food are swallowed at one time
36
What is different about a birds oesophagus?
They possess a crop
37
What is a crop?
It is an outgrowth of the oesophagus used to store food prior to digestion or regurgitation
38
In pigeons, what does the crop do?
Secretes a nutritional fluid to feed hatchlings for several days - pigeon milk
39
What is the stomach?
Muscular sac to receive, churn and process food using gastric juices
40
In carnivores, what do they use the stomach for?
Use it as a storage area when intake is irregular and large quantities of food are eaten
41
What are the gastric juices in the stomach?
HCL plus some enzymes and mucus
42
What is the function of acid secretion?
To prevent food decay by bacteria whilst food is stored prior to digestion
43
Mucosal histology divides the stomach into what?
Glandular and non-glandular epithelium
44
What does the gastric glands delineate?
The cardia, fundus and pylorus
45
What is cardia?
Only found in mammals, marks the transition between stomach and oesophagus, mostly mucous secreting cells
46
What is fundus?
Contains mucus cells, parietal cells (HCL) and chief cells (proteolytic enzymes)
47
What is pylorus?
Contains pyloric glands that create mucous that helps to neutralise acidic chime prior to release into the intestines
48
Where is non-glandular epithelium found?
In the stomach
49
Where do herbivores develop non glandular epithelium?
At the base of the oesophagus
50
In rodents, what results in a loss of gastric glands?
Leads to smooth muscle stomach that uses contractions to churn and mix food
51
Why might a rodent epithelium be keratinised?
To resist mechanical abrasion from insect exoskeletons, grasses and seeds
52
What is a gizzard?
A region of the stomach with thick muscular walls that grinds food against ingested stones
53
What animals have a gizzard?
Crocodiles and alligators
54
What part of the stomach lies before the gizzard?
Glandular part
55
Does a bird possess a gizzard or a crop?
Possess both
56
What joins the oesophagus that then joins the gizzard?
Proventriculus
57
What is the function of the proventriculus?
Secretes gastric fluid to digest the food bolus
58
What does ruminants and camels stomachs have?
4 chambered stomach
59
What are the 4 chambers of the stomach of ruminants and camels?
Rumen, reticulum, omasum and abomasum
60
Where are the rumen, reticulum and omasum derived from?
The oesophagus
61
Where is the abomasum derived from?
The stomach
62
What is the Rumen chamber of the stomach?
Large and serves to receive food from the oesophagus
63
What is the shape of the reticulum chamber of the stomach?
Small and honeycombed
64
What does the rumen and reticulum have in common?
Both are lines with oesophageal epithelium. The food is mixed with saliva and separates into layers of solid and liquid material
65
What is the omasum chamber of the stomach?
This is the third chamber and is lined with oesophageal epithelium but folded into overlapping leaves
66
What is the abomasum chamber of the stomach?
This is the final chamber and is the only chamber that possesses a cardia, fundus and pylorus. This is the true stomach
67
Functions of the liver?
Detoxification of blood and production of bile.
68
What animals have a gall bladder?
Bony fishes, amphibians, reptiles, some birds and most animals
69
What two types of functions happen in the pancreas?
Exocrine and endocrine
70
What are the intestines?
Elongated tube that separates into small and large intestines
71
What does peristalsis do?
Moves food along tract
72
What does mucus do in the intestines?
Protects gut tube walls from enzymes and provide lubrication
73
What do intestinal glands produce?
Enzymes to breakdown carbohydrates, proteins and lipids
74
What nutrients get absorbed by the intestines?
Carbohydrates, amino acids, fatty acids and water
75
What are the three areas of the small intestine?
Duodenum, jejunum and ilium
76
What is the duodenum?
The first part of small intestine that receives chime from stomach and exocrine secretions from the liver and pancreas
77
What do the Brunner's glands in the walls of the duodenum do?
Help neutralise acid from stomach
78
Jejunum and ileum are more distinct in?
Mammals
79
Where does the large intestine pass to?
Anal opening or the cloaca
80
What is the rectum?
Acts as a store before the anus
81
What do the sphincter muscle do?
Control release of content
82
What are the parts of the large intestine?
Ascending colon, transverse colon, descending colon and sigmoid colon
83
Where is the cloaca derived from?
The proctodeum at the end of the embryonic gut tube
84
What species is the cloaca not present in?
Fish or most mammal species because they have separate digestive (anal canal) and urogenital openings
85
Where does the large intestine empty?
Coprodeum
86
Why increase time spent in the digestive tract?
To maximise nutrient intake
87
What is the spiral valve
Helical partition in the gut tube that forces food to wind around a spiral channel, increasing the time spent in the intestines
88
What increases the surface area in the intestines in larval lampreys?
Typhlosole longitudinal fold
89
Does water absorption take place in large or small intestines?
Large
90
In lower vertebrates why is electrolytes and water reabsorbed in large intestines?
Don't concentrate urine well
91
Retrograde peristalsis can push digesta from cloaca to large intestine for?
Further resorption
92
GALT is?
Gut Associated Lymphatic Tissue and is a defence against ingested pathogens and parasites
93
What is down-regulation after food has been digested?
Decrease in cell proliferation or epithelial folding
94
Some animals go into fasting period after digestion, what animals do not?
Endothermic animals ( birds, mammals)
95
Why do birds down-regulate?
For long flights
96
Why do lactating mammals down-regulate?
Increase food intake and intestines enlarge in response
97
What does mechanical breakdown of food allow?
Pieces to be reduced in size and then swallowed
98
What starts the process of digestion?
Enzyme in saliva
99
What does carnassial teeth allow?
Allows soft, sinewy food to be sliced into pieces
100
What do the incisors do?
Snip vegetation
101
What do molars do?
Grind food to break down tough outer layers
102
Why do omnivore have a mixed dentition?
Because they have a mixed dietary intake
103
What acts on food to produce the end products of digestion?
Proteases (proteins), lipases (fats), cellulases, amylase (carbohydrates)
104
What are the end products of digestion?
Amino acids, sugars, fatty acids, vitamins and minerals
105
What is cellulose?
A structural component of all plants and as such is an important carbohydrate. It is insoluble and very resistant to chemical attack
106
How is cellulose broken down?
Fermentation by microorganisms/ bacteria/ protozoans
107
Fermentation releases what?
Organic acids that are used for oxidative metabolism
108
What does fermentation create?
Carbon dioxide and methane
109
Why are fermentation chambers needed?
To allow slow process of fermentation to occur
110
Microbial fermentation in the oesophagus and stomach are?
Foregut fermenters
111
Why regurgitate food?
This process occurs many time to break food up mechanically and chemically.
112
Intestinal fermentation is?
Microbial digestion of cellulose in the intestine
113
Advantage of gastric fermentation 1?
Very good at extracting the most from low-quality foods
114
Advantage of gastric fermentation 2?
Nutrients released early in the digestive tract so more time to absorb them and being able to re-chew food enables a mechanical breakdown of the plant cell walls
115
Advantage of gastric fermentation 3?
Ammonia is taken in by micro-organisms, which are flushed into the abomasum and omasum and digested
116
Advantage of gastric fermentation 4?
Urea taken into camels rumen and turned into ammonia taken up by bacteria (very little urea lost in urine)
117
Advantage of gastric fermentation 5?
Can take a large quantity of food in quickly and then go to a place of safety to digest it
118
Advantage of intestinal fermentation 1?
Food passes through digestive tract prior to fermentation which allows soluble nutrients to be absorbed before fermentation starts.
119
Advantage of intestinal fermentation 2?
Faster than gastric fermentation allowing quick absorption of nutrients and release of forage
120
Advantage of intestinal fermentation 3?
Some practice coprophagy and re-ingest faeces to pass nutrients though the digestive tract a second time - rodents and rabbits
121
What size of herbivores will most likely use intestinal fermentation?
Small
122
What size of herbivore will most likely use gastric fermentation?
Large
123
Why do plants use toxins?
As a form of defence
124
Tannins and caffeine taste?
Bitter
125
What is affected by Marijuana?
Reaction times
126
What type of animals use toxins as a type of defence?
Amphibians
127
What does ruminant saliva contain?
Proteins that bind with tannins to reduce toxicity and reduce effects on digestibility
128
Ruminants that eat a large quantity of tannin-rich food will have a large or small salivary gland?
Large
129
What is the proventriculus?
Glandular part of the stomach
130
Different shapes of the liver causes?
Different body morphology but similar functions
131
Chemicals make food?
Palatable or poisonous
132
Can animals use toxins as a defence?
Yes - amphibians
133
The smaller the animal, the higher?
Metabolic rate which means greater need to digest nutrients quickly
134
Large intestinal herbivores have long enough?
Digestive tract to extract sufficient nutrients
135
What do large herbivores have the body volume for?
To contain large many chambered stomach
136
What advantage does intermediate sized animals have?
Ruminant digestion dependant on quality of forage
137
What type of animals use gastric fermentation?
Animals that can stand harsh environments such as deserts, altitude or harsh winters
138
Advantage of gastric fermentation 6?
Nitrogen used as a resource (not a waste product), important in low protein diets
