Lecture 19 Animal Nutrition and the Digestive System

Question 1

Steps of animal nutrition

Answer 1

Ingestion-food is taken in
digestion-food is taken apart
absorption -food is taken up

Question 2

What is needed to maintain homeostasis

Answer 2

energy/atp

Question 3

3 nutrition needs

Answer 3

A. Chemical energy for cellular processes
B. Organic building blocks for macromolecules
C. Essential nutrients

Question 4

Minerals

Answer 4

simple inorganic nutrients, usually required in small amounts

consuming too much minerals can upset homeostatic balance

Question 5

Vitamins

Answer 5

● Organic molecules
● Required in the diet in very small amounts.
● 13 vitamins are essential for humans.
● Two categories:
○ Fat-soluble (ADEK)
○ Water-soluble.

Question 6

Essential fatty acids

Answer 6

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).

Question 7

Essential amino acids

Answer 7

● 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.

Question 8

Malnutrition

Answer 8

Dietary Deficiencies

Malnutrition is a failure to obtain adequate nutrition.

undernourishment results when a diet does not provide enough chemical energy.

Question 9

Digestive system process

Answer 9

1. ingestion
   2.digestion
   3.absorption
   4.elimination

Question 10

Ingestion

Answer 10

the act of eating or feeding

Question 11

digestion

Answer 11

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.

Question 12

Intracellular digestion

Answer 12

food particles are engulfed by phagocytosis and liquids by pinocytosis (small vesicles).

Question 13

extracellular digestion

Answer 13

is the breakdown of food particles outside of cells.
○ It occurs in compartments that are continuous with the
outside of the animal’s body

Question 14

Where does gastrovascular cavity function in (2 places)

Answer 14

functions in both digestion and distribution of nutrients.

Question 15

What do accessory glands do (digestive system)

Answer 15

secrete digestive juices through ducts into the alimentary canal

Question 16

alimentary canal (digestive system)

Answer 16

salivary glands, the pancreas, the liver, and the gallbladder

Question 17

The Oral Cavity, Pharynx, and Esophagus

Answer 17

● 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.

Question 18

Digestion in the stomach
(what does it create)

Answer 18

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.

Question 19

(Chemical Digestion in the Stomach) what is gastric juice made up of

Answer 19

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.

Question 20

Production of gastric juice

Answer 20

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.

Question 21

Positive feedback loop: Pepsin activates Pepsinogen

Answer 21

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.

Question 22

Digestion in the Small Intestine

Answer 22

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.

Question 23

small intestine

Answer 23

longest compartment of the alimentary
canal.

Question 24

Small Intestine and Accessory glands

Answer 24

● 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

Question 25

duodenum

Answer 25

the first portion of the small intestine

Question 26

Small Intestine form-function

Answer 26

The small intestine has a huge surface area, due to villi and microvilli that are exposed to the intestinal lumen

Question 27

Absorption in the Small Intestine

Answer 27

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.

Question 28

Hepatic portal vein

Answer 28

The hepatic portal vein carries nutrient-rich blood from the capillaries of the villi to the liver, then to the heart.

Question 29

Bile

Answer 29

-made in the liver and stored in the gallbladder
-bile salts facilitate digestion of fats and are a major of component of bile

Question 30

Absorption of fat

Answer 30

● 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

Question 31

What is part of Microbiome, adaptations and hormonal system

Answer 31

large intestine

Question 32

What is the Large intestine

Answer 32

-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

Question 33

Absorption in the large intestine

Answer 33

● 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.

Question 34

The human microbiome(microorganisms)

Answer 34

At the interface of health and disease

Question 35

the microbiome

Answer 35

-the collection of the microorganisms living on the body

differences in the microbiome associated with diet, disease, and the age

Question 36

Stomach and intestinal adaptions (Carnivores)

Answer 36

have large, expandable stomachs

Question 37

Stomach and intestinal adaptions (herbivores)

Answer 37

have fermentation chambers, where mutualistic (beneficial to all parties) microorganisms digest cellulose

Question 38

Stomach and intestinal adaptions (herbivores and omnivores)

Answer 38

they generally have longer alimentary canals than carnivores, meaning there is a longer time needed to digest vegetation

Question 39

Regulation of Appetite and Consumption

Answer 39

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.

Question 40

How hormones regulate appetite

Answer 40

Hormones regulate long-term and short-term appetite by affecting a “satiety center” in the brain

Question 41

Ghrelin

Answer 41

a hormone secreted by the stomach wall, triggers feelings of hunger before meals

Question 42

Insulin and PYY

Answer 42

a hormone secreted by the small intestine after meals, both suppress appetite

Question 43

Leptin

Answer 43

produced by adipose (fat) tissue, also suppresses appetite and plays a role in regulating body fat levels

Question 44

Insulin

Answer 44

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

Question 45

Glucagon

Answer 45

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

Question 46

What does the liver do?

Answer 46

The liver regulates nutrient distribution, interconverts many organic molecules, and detoxifies many organic molecules.