Lecture 19 Animal Nutrition and the Digestive System Flashcards
Steps of animal nutrition
Ingestion-food is taken in
digestion-food is taken apart
absorption -food is taken up
What is needed to maintain homeostasis
energy/atp
3 nutrition needs
A. Chemical energy for cellular processes
B. Organic building blocks for macromolecules
C. Essential nutrients
Minerals
simple inorganic nutrients, usually required in small amounts
consuming too much minerals can upset homeostatic balance
Vitamins
● Organic molecules
● Required in the diet in very small amounts.
● 13 vitamins are essential for humans.
● Two categories:
○ Fat-soluble (ADEK)
○ Water-soluble.
Essential fatty acids
Animals can synthesize many of the fatty acids they need.
The essential fatty acids must be obtained from the diet and include certain unsaturated fatty acids (i.e., fatty acids with one or more double bonds).
Essential amino acids
● Animals require 20 amino acids and
● can synthesize about half from molecules in their diet.
● The remaining amino acids, the essential amino acids, must be obtained from food in prefabricated form.
Malnutrition
Dietary Deficiencies
Malnutrition is a failure to obtain adequate nutrition.
undernourishment results when a diet does not provide enough chemical energy.
Digestive system process
- ingestion
2.digestion
3.absorption
4.elimination
Ingestion
the act of eating or feeding
digestion
The process of breaking food down into molecules small enough to absorb.
Mechanical digestion, chewing or grinding,
increases the surface area of food.
Chemical digestion splits food into small molecules that can pass through membranes; these are used to build larger molecules.
Intracellular digestion
food particles are engulfed by phagocytosis and liquids by pinocytosis (small vesicles).
extracellular digestion
is the breakdown of food particles outside of cells.
○ It occurs in compartments that are continuous with the
outside of the animal’s body
Where does gastrovascular cavity function in (2 places)
functions in both digestion and distribution of nutrients.
What do accessory glands do (digestive system)
secrete digestive juices through ducts into the alimentary canal
alimentary canal (digestive system)
salivary glands, the pancreas, the liver, and the gallbladder
The Oral Cavity, Pharynx, and Esophagus
● Food processing begins in the oral cavity.
● Teeth break down the food and salivary
glands deliver saliva to lubricate food.
● Saliva contains mucus, a viscous mixture
of water, salts, cells, and glycoproteins.
● Saliva also contains amylase, which
breaks down starch.
Digestion in the stomach
(what does it create)
The stomach stores food and processes it into a liquid
suspension.
The stomach secretes gastric juice.
The mixture of ingested food and gastric juice is called chyme.
(Chemical Digestion in the Stomach) what is gastric juice made up of
Gastric juice is made up of hydrochloric acid (HCl) and pepsin.
● Hydrochloric acid: Gastric juice has a low pH of about 2, which kills bacteria and denatures
proteins.
● Pepsin is a protease, which breaks peptide bonds to cleave proteins into smaller peptides.
Production of gastric juice
1.Pepsinogen and HCl are introduced into the lumen of the stomach
2. HCl converts pepsinogen to pepsin
3. Pepsin the activities more pepsinogen, starting a chain reaction. Pepsin begin the chemical digestion to proteins.
Positive feedback loop: Pepsin activates Pepsinogen
1.Pepsinogen and
HCl introduced
into lumen.
2.HCl converts
pepsinogen to
pepsin.
3.Pepsin
(active
enzyme)
Pepsin activates
more pepsinogen,
starting a chain
reaction.
Digestion in the Small Intestine
Enzymatic digestion is completed
as peristalsis moves the chyme
and digestive juices along the
small intestine.
Absorption is uptake of small
molecules by body cells.
Elimination is the passage of
undigested material out of the
digestive system.
small intestine
longest compartment of the alimentary
canal.
Small Intestine and Accessory glands
● Most enzymatic hydrolysis of macromolecules from
food occurs here.
● Here, chyme from the stomach mixes with digestive juices from the pancreas, liver, gallbladder, and the small intestine itself
duodenum
the first portion of the small intestine
Small Intestine form-function
The small intestine has a huge surface area, due to villi and microvilli that are exposed to the intestinal lumen
Absorption in the Small Intestine
The small intestine has a huge surface area due to villi and microvilli that are exposed to the intestinal lumen.
The enormous microvillar surface creates a brush border that greatly increases the rate of nutrient absorption.
Transport across the epithelial cells can be passive or active, depending on the nutrient.
Hepatic portal vein
The hepatic portal vein carries nutrient-rich blood from the capillaries of the villi to the liver, then to the heart.
Bile
-made in the liver and stored in the gallbladder
-bile salts facilitate digestion of fats and are a major of component of bile
Absorption of fat
● Epithelial cells absorb fatty acids and monoglycerides and recombine them into triglycerides.
● These fats are coated with phospholipids,
cholesterol, and proteins to form water-soluble
chylomicrons.
● Chylomicrons are transported into a lacteal, a
lymphatic vessel in each villus.
● Lymphatic vessels deliver chylomicron-containing
lymph to large veins that return blood to the heart
What is part of Microbiome, adaptations and hormonal system
large intestine
What is the Large intestine
-alimentary canal ends with the large intestine. it includes the colon, caecum, and rectum
-colon leads to the rectum and anus
-the cecum aids in the fermentation of plant material and connects where there small and large intestines meet
Appendix - the human cecum extension; plays a minor role in immunity
Absorption in the large intestine
● The colon completes the recovery of water that began in the small intestine.
● Feces, the wastes of the digestive system,
become more solid as they move through the
colon.
● The coexistence of humans and many bacteria involves mutualistic symbiosis. Some intestinal bacteria produce vitamins.
● They also regulate the development of the
intestinal epithelium and the function of the innate immune system.
The human microbiome(microorganisms)
At the interface of health and disease
the microbiome
-the collection of the microorganisms living on the body
differences in the microbiome associated with diet, disease, and the age
Stomach and intestinal adaptions (Carnivores)
have large, expandable stomachs
Stomach and intestinal adaptions (herbivores)
have fermentation chambers, where mutualistic (beneficial to all parties) microorganisms digest cellulose
Stomach and intestinal adaptions (herbivores and omnivores)
they generally have longer alimentary canals than carnivores, meaning there is a longer time needed to digest vegetation
Regulation of Appetite and Consumption
nervous and endocrine system
The enteric division of the nervous system helps to regulate the digestive process.
The endocrine system also regulates digestion
through the release and transport of hormones.
Hormones regulate long-term and short-term
appetite by affecting a “satiety center” in the
brain.
How hormones regulate appetite
Hormones regulate long-term and short-term appetite by affecting a “satiety center” in the brain
Ghrelin
a hormone secreted by the stomach wall, triggers feelings of hunger before meals
Insulin and PYY
a hormone secreted by the small intestine after meals, both suppress appetite
Leptin
produced by adipose (fat) tissue, also suppresses appetite and plays a role in regulating body fat levels
Insulin
Insulin acts on nearly all body cells to stimulate glucose uptake from blood
Brain cells are an exception; they can take up
glucose whether or not insulin is present.
Homeostatic glucose regulation
Glucagon
Glucagon and insulin are both produced in the
islets of the pancreas.
Pancreatic alpha cells make glucagon, and beta cells make insulin.
Homeostatic glucose regulation
What does the liver do?
The liver regulates nutrient distribution, interconverts many organic molecules, and detoxifies many organic molecules.
