digestive system Flashcards
1
Q
steps of digestion
A
- ingestion
- digestion
- absorption
- assimilation
- elimination
2
Q
ingestion
A
taking food into the body
3
Q
digestion
A
breaking down food
4
Q
absorption
A
moving food into cells
5
Q
assimilation
A
making food part of the cell
6
Q
elimination
A
removing unused food
7
Q
catabolism (metabolism)
A
larger molecule → smaller molceules + energy
8
Q
anabolism (metabolism)
A
smaller molecules + energy → larger molecule
9
Q
where does digestion take place
A
the gastrointestinal tract / alimentary canal
10
Q
main organs of the gastrointestinal tract
A
- mouth
→ + salivary glands - esophagus
- stomach
- small Intestine
→ + duodenum, jejunum, ileum - caecum (in some cases)
- large Intestine
→ + colon - rectum
11
Q
accessory organs of the gastrointestinaln tract
A
- liver
- gall bladder
- pancreas
12
Q
mastication
A
chewing
13
Q
incisors
A
- teeth at the front
- sharp
- used to cut food
14
Q
canine teeth
A
- in the corner of the mouth
- long roots
- used for grasping and tearing at food
15
Q
premolar teeth
A
- behind the canine teeth
- flat surface
- used for chewing
16
Q
molar teeth
A
- at the back of the mouth
- bigger than premolars
- flatter surface than premolars
- used to chew smaller pieces of food
17
Q
carnivore teeth
A
- canines
- inciosors
- premolars
- few molars
18
Q
herbivore teeth
A
- incisors
- molars
- premolars
- no canines
19
Q
omnivore teeth
A
- incisors
- canines
- molars
- premolars
20
Q
why does the body produce saliva?
A
to start enzyme breakdown of food and to protect the oral mucosa
21
Q
what enzymes are produced in the salivary glands?
A
- amylase (for carbohydrates)
- lingual lipase (for fats)
- lysozyme (acts as antiseptic)
22
Q
oesophagus
A
- tube connecting the mouth to the stomach.
- smooth muscle for moving food
- food + saliva being swallowed down is called a bolus
23
Q
mechanical digestion in the monogastric stomach
A
manual breakdown of food through the contraction of the stomach muscles moving the food towards the small intestine
24
Q
chemical breakdown in the monogastric stomach
A
enzymes breaking down the food
25
monogastric stomach
- single chamber
- musucular bag
- folds (rugae) on the inside
- stomach expands when food enters from the oesophagus
- three layers of muscle; oblique, circular, longitudinal
26
enzymes in the monogastric stomach
- pepsin → breaks protein into amino acids
- gastric lipase → continues to break down fats
27
mucosa of the mongastric stomach
- inner lining of the stomach
- covered in gastric pits which lead to gastric glands
- parietal cells secrete hydrochloric acid
- chief cells secrete proteases
- neck cells secrete mucus
28
mucus
- secreted in the mucosa of the stomach
- protects the stomach lining from acids
- prevents auto-digestion (stomach digesting itself)
29
small intestine
- mucosa is the innermost layer → made of villi that increase surface area for absorption + lacteals for fat absorption
- more enzymes to further break down food
30
mechanisms for absorption
- osmosis → across a semipermeable membrane
- diffusion → from high concentration to low concentration
- active transport → from low concentration to high concentration, requiring cellular work
31
three parts of the small intestine
1.) duodenum
2.) jejunum
3.) ileum
32
caecum
large organ containing micro-organisms specialised for digestion of cellulose (hindgut fermentation)
33
large intestine
- no enzymes made in the large intestine
- water + some nutrients absorbed back into the body
34
hindgut fermenters
efficient at digesting cellulose through fermentation in the caecum / large intestine → produce bacteria to digest food which produce the enzymes necessary to break down cellulose
35
examples of hindgut fermenters
- guinea pigs
- horses
- rabbits
36
coprophagy
when animals eat a kind of faeces called caecotroph → gives the animal two chances at digesting the nutrients in their food, making their digestive systems very efficient
37
examples of animals that exhibit coprophagy
- capybaras
- hamsters
- rabbits
- chimps
- pigs
38
liver functions
- bile production + excretion
- excretion of bilirubin, cholesterol, hormones + drugs
- metabolism of fats, proteins + carbs
- enzyme activation
- storage of glycogen, vitamins + minerals
- synthesis of plasma proteins, such as albumin, + clotting factors
39
gallbladder functions
- stores and concentrates bile from the liver
- bile is released into the first section of the small intestine (duodenum)
40
pancreas functions
- makes alkaline pancreatic juices and enzymes
- contains bicarbonate, an alkaline substance that acts to neutralise stomach acids
- makes hormones
41
ruminant
- efficient at digesting cellulose through fermentation + 'chewing the cud'
- food is digested by bacteria, which produce the enzymes to break down cellulose → bacteria located in the rumen
- ruminants don't have top incisors, but have a dental pad
42
ruminant stomach segments
- rumen
- reticulum
- omasum
- abomasum
43
rumen
- largest segment of the ruminant stomach
- rely on bacteria to produce enzymes
- bacterial fermentation
- fats absorbed in the rumen
- breaks down food
- releases methane through eructation (burping)
- stores undigested plant material
- absorbs fatty acids and cellulose
44
reticulum
- separated from the rumen by a muscle fold
- contracts for mechanical digestion
- has a honeycomb-like filter that stops large particles entering the omasum
45
omasum
- grinds + squeezes
- absorbs water + nutrients (fatty acids)
- filters large food particles to be returned to the reticulum
46
abomasum
- final compartment
- known as the true / actual stomach
- similar to monogastric stomach
- hydrochloric acid and enzymes are secreted for nutrient breakdown
- symbiotic bacteria is digested in the abomasum and is a main source of protein
