Chapter 41 Flashcards

1
Q

Animal’s diet must supply

A
  • chemical energy
  • organic molecules
  • essential nutrients
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2
Q

Main stages of food processing:

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

Evolutionary adaptations of vertebrate digestive systems

A

correlate with diet

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4
Q

Feedback circuits regulate

A
  • digestion
  • energy storage
  • appetite
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5
Q

Animal’s fall into three nutrition categories:

A
  1. Herbivores (eat mainly plants and algae)
  2. Carnivores (eat other animals)
  3. Omnivores (regularly consume animals as well as plants/algae)

*most animals are opportunistic feeders

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6
Q

Animal’s diet provides:

A
  • chemical energy (converted to ATP = power for cellular processes)
  • organic building blocks
  • Essential nutrients
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7
Q

Essential nutrients

A

materials that an animal cannot assemble from simpler organic molecules; must be obtained from the diet.

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8
Q

(Four) classes of essential nutrients

A
  1. essential amino acids
  2. Essential fatty acids
  3. Vitamins
  4. Minerals
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9
Q

Animals and their Aminos

A

require 20 amino acids

  • can synthesize about half from their diet
  • the essential amino acids (remaining) must be obtained from food in preassembled form
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10
Q

Essential amino acids

A

obtained from ingestion of “complete” proteins

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11
Q

Essential fatty acids

A

must be obtained from the diet and include certain unsaturated fatty acids
-deficiencies in fatty acids are rare

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12
Q

unsaturated fatty acids

A

fatty acids with one or more double bonds

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13
Q

Vitamins

A

are organic molecules required in a diet in very small amounts
-13 essential for humans

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14
Q

Vitamin (two) categories

A
  1. Fat-soluble

2. Water-soluble

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15
Q

Minerals

A

simple inorganic nutrients, usually required in small amounts; ingestion of large amounts of some minerals can upset homeostatic balance

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16
Q

Malnutrition

A

is a failure to obtain adequate nutrition

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17
Q

Ingestion

A

is the act of eating

-strategies for extracting resources from food differ widely among animal species

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18
Q

Suspension feeders

A

(many aquatic animals) which sift small food particles from the water

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19
Q

Substrate feeders

A

animals that live in or on their food source

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20
Q

Fluid feeders

A

suck nutrient-rich fluid from a living host

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21
Q

Bulk feeders

A

eat relatively large pieces of food, less frequently

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22
Q

Types of feeders

A
  1. Suspension feeders
  2. Substrate feeders
  3. Fluid feeders
  4. Bulk feeders
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23
Q

Digestion

A

The process of breaking down food into molecules small enough to absorb:

  1. Mechanical digestion (chewing; increases size of food)
  2. Chemical digestion (splits food into small molecules that can pass through membranes)
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24
Q

Chemical digestion

A
  • used to build larger molecules

- enzymatic hydrolysis splits bonds in molecules with the addition of water

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25
Absorption
the uptake of nutrients by body cells
26
Elimination
passage of undigested material out of the digestive system
27
Digestive compartments
(most animals process food in them) reduce risk of an animal digesting its own cells and tissues
28
Intracellular digestion
*sponges food particles are engulfed by phagocytosis; food vacuoles (containing food) fuse with lysosomes containing hydrolytic enzymes.
29
Extracellular digestion
is the breakdown of food particles outside of cells; occurring in compartments continuous with outside of animal's body cavity.
30
Gastrovascular cavity
(animals with simple body plans) have this; functions in both digestion and distribution of nutrients
31
more complex animal's general digestive structure:
digestive tube with two openings (mouth and anus)
32
Alimentary canal
(aka: complete digestive tract) is the digestive tube with mouth and anus as openings * has specialized regions that carry out digestion and absorption in stepwise fashion.
33
Contents of mammalian digestive system
- alimentary canal | - accessory glands (that secrete digestive juices through ducts)
34
Mammalian accessory glands
- salivary gland - pancreas - liver - gallbladder
35
Peristalsis
method at which food is pushed along tract; rhythmic contractions of muscles in the wall of the canal
36
sphincters
(valves) that regulate movement of material between compartments
37
First stage of digestion
- mechanical - occurs in oral cavity - salivary glands deliver saliva (lubricate food) - teeth chew food (increasing surface area) - salivary amylase initiates breakdown of glucose polymers - saliva also contains mucus (salts, water, cells, glycoproteins)
38
Second stage digestion
- stomach stores food and begins digestion of proteins; secretes gastric juice, converting meal to chyme. - gastric juice pH=2; kills bacteria and denatures proteins
39
Gastric juice contents
HCl and pepsin
40
Pepsin
protease; protein-digesting enzyme which cleaves proteins into smaller peptides
41
Parietal cells
secrete hydrogen and chloride ions separately into the stomach lumen (cavity)
42
Chief cells
secrete inactive pepsinogen
43
Pepsinogen
is activated to pepsin when mixed with HCl in stomach
44
Mucus in stomach
protects the stomach lining from gastric juice
45
Gastric ulcers
lesions in lining, caused mainly by H. Pylori
46
Small intestine
the longest section of the alimentary canal; site of most enzymatic hydrolysis of macromolecules from food
47
Duodenum
is the first portion of small intestine; where stomach chyme mixes with digestive juices from pancreas, liver, gallbladder and SI itself
48
Pancreas
produces proteases, which are activated in the lumen of duodenum: - trypsin - chymotrypsin *solution is alkaline and neutralized acidic chyme
49
Bile
aids in digestion and absorption of fats in SI - made in liver - stored in gallbladder - also destroys nonfunctional RBC's
50
Villi and Microbilli
exposed to the intestinal lumen; increasing surface area of SI -creates a brush border that greatly increases rate of nutrient absorption
51
SI transport across epithelial cells
can be (depending on the nutrient): - passive - active
52
Hepatic Portal Vein
carries nutrient-rich blood from the villi capillaries to the liver, then to the heart
53
Liver
- regulates nutrient distribution - interconverts many organic molecules - detoxifies many organic molecules
54
Epithelia cells in SI
absorb fatty acids and momoglycerides; recombines them into triglycerides
55
Colon of LI
attached to SI - recovers water that has entered alimentary canal - houses bacteria that live on unabsorbed organic material (e-coli, for example)
56
Cecum
aids in fermentation of plant material; connects where SI and LI meet
57
Human Cecum
contains appendix; plays a minor role in immunity
58
Feces
include undigested material and bacteria; become more solid as they move through colon
59
Vertebrates digestive systems
are variations on a common plan. Most adaptations (intriguing) are often related to diet
60
many carnivores have
large, expandable stomachs
61
herbivores and omnivores
generally have longer alimentary canals than carnivores; reflecting longer time needed to digest vegetation
62
Mutualistic adaptations
some intestinal bacteria produce vitamins; also regulate development of intestinal epithelium and function of innate immune system
63
ruminants
most elaborate adaptations for herbivorous diet evolved in animals -most herbivores have fermentation chambers where mutualistic microorganisms digest cellulose
64
helps to regulate digestive processes
- enteric division of nervous system | - endocrine system
65
Regulation of energy storage
- body stores E-rich molecules (not needed right away for metabolism - in humans: liver 1st, muscle cells *in the polymer glycogen - excess energy stored as fat *adipose tissue
66
most space-efficient storage tissue
adipose tissue
67
when fewer calories are taken in than needed
the human body expends liver glycogen first, then muscle glycogen and fat.
68
Ghrelin
hormone secreted by stomach wall triggers feelings of hunger before meals
69
Insulin and PYY
hormones secreted by the small intestine after meals, both suppress appetite
70
Leptin
produced by adipose tissue; also suppressed appetite and plays role in regulating body fat levels.