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BIO 1110 > Lecture 8: Animal Digestion > Flashcards

Lecture 8: Animal Digestion Flashcards

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1
Q

What are the 4 steps of food processing?

A
  1. Ingestion
  2. Digestion
  3. Absorption
  4. Elimination
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2
Q

Define ingestion and where it occurs in a body with an alimentary canal. Which step of food processing is it?

A

Ingestion is the act of eating, this can vary between different animals.
Ingestion occurs in the mouth (oral cavity) of the alimentary canal and is the first step to processing food.

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3
Q

Define digestion. What are the two kinds of digestion?

Which step of food processing is it?

A

Digestion is the process of breaking down the large organic molecules of food into smaller molecules animal bodies can use.
Digestion is the second step of food processing.
Two kinds:
mechanical and chemical digestion

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4
Q

Define absorption and where it occurs in a body with an alimentary canal. Which step of food processing is it?

A

Absorption is how the nutrients enter the cells

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5
Q

Define elimination and where it occurs in a body with an alimentary canal. Which step of food processing is it?

A

Elimination is how waste materials leave the body

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6
Q

What are the 4 kinds of ingestion? describe and provide an example of each

A
  1. Suspension and filter feeders: Aquatic animals that sift particles and small organisms out of water
    - ex. baleen whales, sponges
  2. Substrate feeders: live on their food source either for a period of their lives or throughout their whole lives.
    - ex. caterpillars live on leaves until they metamorphosis
  3. Fluid feeders: suck nutrient filled fluids from their food source
    - ex. nectar feeding birds like hummingbirds
  4. Bulk feeders: eat large pieces of food or whole organisms
    - ex. humans
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7
Q

What are the three big energy molecules that come from food? What process are they all important for?

A
  • proteins
  • carbohydrates
  • fats
    Important in cellular respiration process for ATP production
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8
Q

Why does digestion need to occur in animals?

A

Animals cannot use the large organic molecules (proteins, carbs, and fats) directly so they must be digested and broken down into their smaller components

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9
Q

Compare and contrast mechanical and chemical digestion? Where does each occur?

A

Mechanical digestion is the physical break down of large food molecules into smaller particles.
This occurs firstly in the mouth with teeth grinding or chewing and secondly in the stomach with muscular contractions.

Whereas, chemical digestion is the breakdown of large food molecules into smaller compounds through the use of enzymes.
Chemical digestion occurs in the salivary glands of the mouth first and continues all the way through the alimentary canal.

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10
Q

Define intracellular digestion.

A

The breakdown of food particles INSIDE cells. This occurs when cell membranes form a pocket around a large food particle (endocytosis) and the lysosome organelle releases digestive enzymes inside the cell to break down the large food particle

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11
Q

Define extracellular digestion

A

The breakdown of food particles that occurs OUTSIDE of cells and within the digestive cavity (can be either gastrovascular or alimentary canal).
Extracellular digestion can include chemical and/or mechanical digestion.

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12
Q

Compare and contrast intracellular and extracellular digestion?

A

Intracellular digestion and extracellular digestion are both forms of breaking down large food particles into smaller components so animals are able to absorb essential nutrients.

Intracellular digestion is the breakdown of food particles WITHIN cells. Whereas, extracellular digestion occurs outside of cells and within the digestive cavity.

Intracellular digestion is purely an enzymatic process of chemical digestion. Whereas, extracellular digestion can include chemical and/or mechanical digestion.

Intracellular digestion allows for an animal that is reliant on this form of digestion (only Porifera) to be able to digest and absorb nutrients from all areas within the body.
Whereas, in most other animals that rely on a combination of both extracellular and intracellular digestion, digestion and absorption occur in sequential orders at different stages of the digestive cavity.

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13
Q

Which animals use only intracellular digestion?

A

PORIFERA (SPONGES) are the ONLY animals that depend completely on intracellular digestion

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14
Q

T or F: A gastrovascular cavity has one opening where food enters and waste exits? give an example.

A

TRUE.

Phyla Porifera and species Hydra (from phyla cnidaria) are examples of animals with gastrovascular cavities

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15
Q

T or F: in a gastrovascular cavity, digestion and absorption occur all throughout the cavity? why/why not?

A

TRUE. Because organisms with gastrovascular cavities have no circulatory system, instead the GVC extends throughout the entire body so the nutrients can be distributed to all cells in contact with the cavity

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16
Q

T or F: in an alimentary canal, digestion and the processes involved occur sequentially through the animal’s body? why/why not?

A

TRUE. Ingestion through the mouth, moves through the digestive cavity, absorbed in a different area, waste out the anus

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17
Q

In animals with alimentary canals, where does most of the digestion occur/what kind of digestion?
In animals with gastrovascular cavities?

A

In animals with alimentary canals, digestion occurs mostly inside the canal before entering the cells = EXTRACELLULAR. But some intracellular digestion will still occur.

Whereas, in animals with gastrovascular cavities, most of the digestion occurs within the cells = INTRACELLULAR

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18
Q

Why does digestion not occur everywhere within an alimentary canal like it would in a GVC?

A

Digestion occurs in sequential stages within isolated compartments of the alimentary canal because the canal is not in contact with all body cells.
Most animals with ACs, also have a circulatory system to distribute nutrients.

19
Q

What are some advantages of having digestion occur sequentially in alimentary canals?

A

Animals with an AC can ingest more food before the digestion of the current meal is complete due to large storage compartments and sequential processing.
Beneficial for animals in nature who don’t receive regular meals.

Animals with an AC can ingest bigger food items

More diverse diet

Faster metabolism - breaking down large food molecules mechanically in the gut speeds up the process of the food particles being absorbed into body cells

20
Q

Why is a circulatory system beneficial for animals with an alimentary canal?

A

Because the alimentary canal is not in contact with all body cells, so the circulatory system distributes nutrients from where absorption occurs to other cells in different areas of the body.

21
Q

T or F: Alimentary canals are typically found in animals that have circulatory systems? why/why not?

A

TRUE.

Circulatory systems distribute nutrients to different body cells that are not in contact with the alimentary canal.

22
Q

What is a major difference between a gastrovascular cavity and an alimentary canal (complete gut)?

A

Gastrovascular cavities extend throughout the entire body of an animal and reaches all body cells. Whereas, an alimentary canal does not extend to all body cells and nutrient absorption is isolated to the small intestine.

23
Q

Is the trend in animal evolution toward increasing dependence on intra- or extracellular digestion? why?

A

Extracellular digestion because larger and more diverse food sources can be introduced into diets (key adaptation)

24
Q

T or F: Everything that happens in the alimentary canal is extracellular? why?

A

TRUE, it all occurs within the digestive cavity (AC).

25
Q

Where in the alimentary canal do carbohydrates, proteins, and fats begin chemical digestion?

A

Carbohydrates: ORAL CAVITY

Proteins: STOMACH

Fats: DUODENUM of the SMALL INTESTINE

26
Q

What are the structures and functions of the oral cavity? Which part of food processing occurs here? which of the 3 main food molecules begins chemical digestion here?

A

Both ingestion and some digestion occur in the oral cavity.

Structures: tongue, teeth, salivary glands

Functions:

  • tongue to move food around
  • teeth to mechanically digest (grind/chew)
  • salivary glands begin to chemically digest CARBOHYDRATES with enzymes
27
Q

What are the structures and functions of the esophagus?

A

The esophagus is the passage between the mouth and stomach that is regulated by muscular sphincters and the epiglottis. It is the passage way for food to move via peristalsis from the mouth to the stomach

28
Q

What is a sphincter?

A

Sphincters protect different compartments of the digestive tract

29
Q

What is the epiglottis?

A

The epiglottis is a flap that blocks the trachea while eating so that food does not enter the lungs

30
Q

What is peristalsis?

A

Wave-like muscle contractions in the esophagus that push chewed food down from the mouth to the stomach

31
Q

What are the 5 major compartments of the alimentary canal?

A
  1. Oral cavity
  2. Esophagus
  3. Stomach
  4. small intestine
  5. large intestine
32
Q

Describe the function of the 3 accessory organs and to which major component of the alimentary canal are they CONNECTED to?

A
  1. liver: produces bile
  2. gallbladder: stores and concentrates bile until it is needed in the duodenum.
  3. pancreas: secretes alkaline pancreatic juice into the duodenum and neutralizes acid chyme
    - enzymes sent from the pancreas to the duodenum help complete the breakdown of carbs, proteins, and fats.

These are connected to the duodenum in the small intestine.

33
Q

What are the structures and functions of the stomach? Which of the 3 main food molecule begins chemical digestion here?

A

Structure: The stomach is a compartment that contains RUGAE which are accordion-like folds that can expand to accommodate food.

Function: The stomach performs MUSCLE CONTRACTIONS to MECHANICALLY break down food and released stomach ACID and ENZYMES to CHEMICALLY break down PROTEINS

34
Q

What is the result of the mechanical and chemical digestion in the stomach?

A

the chemical breakdown of proteins with stomach acid and enzymes combined with the mechanical churning creates ACIDIC CHYME.

35
Q

What are the structures and function of the small intestine? Which of the 3 major food molecules begins chemical digestion here?

A

Chyme that was created in the stomach enters the first segment of the small intestine called the DUODENUM through a sphincter.

Structure:

  1. first segment: Duodenum
  2. second segment: jejunum and ileum
  3. Villi: projections that grow off the circular folds of the intestinal lining
  4. Microvilli: projections off the cells that line the villi
  5. Major function of the duodenum is CHEMICAL DIGESTION of FATS though some absorption occurs here too.
  6. Function of the jejunum and ileum is nutrient ABSORPTION

3 & 4. Function of villi and microvilli and circular folds: increase surface area for increased absorption of minerals.

36
Q

T or F: most chemical digestion occurs in the first segment of the small intestine (the duodenum)?

A

TRUE.

37
Q

Where is bile produced? Where is it sent? What is its function?

A

Bile is produced in the LIVER and stored in the GALLBLADDER where it is concentrated until it is needed in the DUODENUM where it begins to chemically digest FATS.

38
Q

T or F: Chemical digestion occurs in the accessory organs?

A

FALSE. The accessory organs produce the enzymes that are necessary for the chemical digestion that occurs in the duodenum of the small intestine.

39
Q

How does chyme move through the small intestine?

A

Peristalsis! Wave-like muscle contractions that move chyme.

40
Q

Which major component of the alimentary canal does the majority of nutrient absorption occur?

A

The second section of the following the duodenum of the SMALL INTESTINE (structures: jejunum and ileum)

41
Q

What are the 3 structures of the large intestine and their functions? Which is the major component of the 3?

A

Structure:

  1. colon - the major component
  2. cecum
  3. rectum

Function: collective main function is to absorb water and solidify species

  1. the colon absorbs water
  2. cecum: fermentation chamber - enlarged in herbivores
  3. rectum: feces storage until elimination through anus
42
Q

What are two general adaptations for plant vs. meat based diets?

A
  1. teeth

2. digestive systems

43
Q

Contrast animal teeth that are adapted for meat vs. plant based diets?

A
  • Carnivores have large canines and less molars
  • molars are usually sharp to tear flesh
  • possess carnassial pair of molars that have a space between them to hold bones
  • Herbivores generally lack large canines and have many flattened molars to grind and chew cellulose and plant materials
  • some herbivores do have large canines (ex. gorillas) for defense
  • must chew a lot before ingesting plant material because cellulose is hard to break down
  • usually have a large space (diastema) between their incisors and their molars for elongated faces that allows them to see surroundings while they eat.
44
Q

How do carnivore digestive systems differ from herbivore digestive systems?

A

Carnivores:

  • Stomach is much more expandable than a herbivores to be able to store food for longer periods of time and eat as much as they can at once.
  • reduced cecum because they do not need to ferment much
  • reduced large intestine, likely cause nutrients from meat are easier to break down

Herbivores:

  • enlarged cecum for fermenting (with bacteria) hard to digest plant materials like fibres
  • alimentary canal is more extensive because plants take longer to digest and more surface area to absorb

BIO 1110 (24 decks)

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