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Title: Chapter 41 Animal Nutrition
Description: 2nd semester Introduction to BIOL 2200 University of Virginia Instructor: Matthew Volny
Description: 2nd semester Introduction to BIOL 2200 University of Virginia Instructor: Matthew Volny
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Chapter 41: Animal Nutrition
Monday, April 1 8, 2 016
5:34 PM
Nutrition: Food being taken in, up and apart
Herbivores:
Omnivores:
Carnivores:
An animal's diet must supply chemical energy, organic molecules, and
essential nutrients
An adequate diet must satisfy three nutritional needs
1
...
Organic building blocks for macromolecules
3
...
Include essential amino acids, fatty acids, vitamins and
minerals
ii
...
Obtained from an animals diet
Essential Amino Acids
Animals require 20 amino acids to make proteins
Remaining amino acids must be obtained from food in
prefabricated form and therefore called essential amino acids
Many animals including adult humans require 8 amino acids
Essential Fatty Acids
Many animals lack the enzyme to form the double bonds found in
certain required fatty acids
Molecules that must be obtained from the diet are considered
essential fatty acids
Vitamins
Organic molecules that are required in the diet in very small
amounts
Molecules that must be obtained from the diet are considered
essential fatty acids
Vitamins
Organic molecules that are required in the diet in very small
amounts
Needed in small amounts because many serve as enzyme
cofactors so they're unchanged even when they take part in a
Crxn
For humans 13 vitamins have been identified
Classified as water-‐soluble or fat-‐soluble
Minerals
Inorganic nutrients
Diverse functions
Dietary Deficiencies
Malnutrition: A failure to obtain adequate nutrition
Under-‐nutrition: A diet that fails to provide adequate sources of chemical
energy
i
...
Eating disorders
Can diet influence the frequency of birth defects?
Yes, there is a controlled study that provides evidence that vitamin
supplementation protects against neural tube defects, at least after the
first pregnancy
...
The main stages of food processing are ingestion, digestion, absorption and
elimination
1
...
Digestion: Food is broken down into molecules small enough for the
body to absorb
i
...
Chewing) normally precedes
chemical digestion
ii
...
Enzymatic hydrolysis: Chemical digestion by enzymes that
break bonds by adding water
ii
...
Enzymatic hydrolysis: Chemical digestion by enzymes that
break bonds by adding water
3
...
Elimination: Completes the process as undigested material passes
out of the digestive system
Intracellular digestion is hydrolysis inside food vacuoles (which are the simplest
digestive compartments)
Occurs after a cell engulfs solid food by phagocytosis or liquid food by
pinocytosis
...
A central cavity with a single
opening -‐-‐-‐> exists in cnidarians and flatworms
Complete digestive tract aka the alimentary canal is a digestive tube extending
between two openings, a mouth and anus
...
The accessory glands include three
pairs of salivary glands, the pancreas, the liver and the gallbladder
...
Ingestion occurs in the oral cavity
i
...
Ingestion occurs in the oral cavity
i
...
Meanwhile the salivary glands deliver saliva through ducts to
the oral cavity
...
Saliva initiates
chemical digestion while also protecting the oral cavity
...
Enzyme amylase hydrolyzes starch and glycogen into smaller
polysaccharides
iv
...
Tongue aids in the digestive process by evaluating ingested
materials and allowing further passage
...
The pharynx (throat region) opens to two passageways
1) The trachea (windpipe) leads to the lungs
2) The esophagus connects to the stomach
2
...
Stomach stores food and begins digestion of proteins
...
Secretes a digestive fluid called gastric juice and mixes it with
food through a churning action
...
iii
...
This low pH denatures proteins in food,
increasing exposure of peptide bonds
...
Breaks peptide bonds into smaller
polypeptides
iv
...
Mucus secreted by the cells
in gastric glands protects against self-‐digestion
...
i
...
cell division adds a new epithelial layer before they are fully
eroded by digestive juices
...
Components of gastric juice are produced by two types of cells
in the gastric glands of the stomach
...
At the same time C l-‐ ions diffuse into the
lumen through specific membrane channel of the
parietal cells
...
HCl snips off a small portion of
the pepsinogen exposing its active site making it pepsin
Positive feedback: Pepsin itself helps activate the
remaining pepsinogen
...
This generates pepsin which in
turn activates more pepsinogen
...
Chemical digestion is facilitated by the churning action of the
stomach
...
Peristaltic
contractions empty the contents of the stomach every 2-‐6
hours
...
Digestion in the Small Intestine
i
...
The first 10 inches forms the duodenum
...
ii
...
Bicarbonate
neutralizes the acidity of the chyme and acts as a buffer
...
Bile: mixture of substances made in the liver but stored and
concentrated in the gallbladder
...
Absorption in the Small Intestine
i
...
Villi: Finger-‐like projection of the inner surface of the small
intestine
4
...
Absorption occurs at highly folded surfaces
ii
...
Microvilli: microscopic cellular membrane protrusions that
increase the surface area of cells and minimize any increase in
volume
...
Depending on the nutrient, transport across the epithelial cells can
be passive or active
v
...
From the liver the blood travels to the heart and then to other
tissues and organs
1) Allows the liver to regulate the distribution of nutrients to the
rest of the body
2) Allows the liver to remove toxic substances before the blood
circulates broadly
vi
...
Processing in the Large Intestine
i
...
Large intestine = colon, cecum and rectum
iii
...
The longer end is the colon ( 1
...
The other portion is called the cecum, which is important for
fermenting ingested material
...
Colon recompletes the reabsorption of water that begins in the
small intestine
...
Feces: wastes of the digestive system
...
Rectum: terminal portion of the large intestine, where the feces are
stored until they can be eliminated
...
Between rectum and anus are
two sphincters ( one is voluntary and one is involuntary)
Evolutionary adaptations of vertebrate digestive systems correlate with diet
Dental Adaptations
Different types of teeth meant to process different kinds of food
Omnivores, Herbivores and Carnivores all have different dental lay outs
Stomach and Intestinal Adaptations
Large expandable stomachs are common in carnivorous vertebrates
Length of the digestive system in different vertebrates
...
( Longer tracts allows for more time for
digestion and more surface area to absorb nutrients)
Mutualistic Adaptations
There are an estimated 10-‐100 trillion bacteria that live in the human
digestive system
...
Microbiome: collection of bacteria
Scientist identify the bacteria as beneficial or harmful using DNA
sequencing approach based on PCR
...
e
...
pylori-‐-‐> leads to a near complete elimination from the stomach of
all other bacterial species
...
2) In horses, koalas and elephants, microorganisms are housed
in large cecum
3) In rabbits and some rodents, mutualistic bacteria live in the
large intestine and in the cecum
...
Instead they obtain
all of their energy from mutualistic bacteria inside their body
Feedback circuits regulate digestion e nergy storage, and appetite
Enteric division: Branch of the nervous system that is dedicated to the digestive
organs and regulates these events as well as peristalsis in the small and large
Giant tube worm has no digestive system or mouth
...
Hormones
released by the stomach and duodenum help ensure that digestive secretions
are present only when needed
...
CCK stimulates the
release of digestive enzymes from the pancreas and of the bile from the
gallbladder and Secretin stimulates the pancreas to release HCO3-‐ which
neutralizes chyme
- If the cyme Is rich in fat, high levels of CCK and secretin inhibit peristalsis
and secretion of gastric juices
...
Stored in glycogen
...
When blood glucose levels rise above normal, the secretion of insulin
triggers the uptake of glucose from the blood into body cells, decreasing
BG conc
2
...
Both hormones are produced in the pancreas
...
Each pancreatic islet has alpha cells, which make
glucagon, and beta cells which makes insulin -‐-‐-‐> make up only 1-‐2% of
the mass of the pancreas
...
Each pancreatic islet has alpha cells, which make
glucagon, and beta cells which makes insulin -‐-‐-‐> make up only 1-‐2% of
the mass of the pancreas
...
Two types
Type 1: Insulin-‐dependent diabetes
Auto-‐immune disorder in which the immune system destroys the beta
cells of the pancreas, destroying a persons ability to make insulin
Type 2: Non-‐insulin dependent diabetes
Failure of target cells to respond normally to insulin
Insulin is produced but target cells fail to take up glucose from the blood
so the BG levels remain elevates
Ghlerin: hormone secreted by the stomach wall that triggers feelings of hunger before
meals
PYY: secreted by small intestine after meals, acts as an appetite suppressant that
counters ghlerin
Leptin: hormone produced by adipose tissue, suppressing appetite; plays major role in
regulating body fat levels
Title: Chapter 41 Animal Nutrition
Description: 2nd semester Introduction to BIOL 2200 University of Virginia Instructor: Matthew Volny
Description: 2nd semester Introduction to BIOL 2200 University of Virginia Instructor: Matthew Volny