Bio Chapter 41- Animal Nutrition/ Digestion

Herbivores

Animals that eat mainly plants or algae

Carnivores

Animals that eat other animals

Omnivores

Animals that regularly consume other animals as well as plants or algae

Most animals are also _______ feeders

opportunistic

An animal's diet must provide...

- Chemical energy for cellular processes
- Organic building blocks for macromolecules

essential nutrients

Required materials that an animal cannot assemble from simpler organic molecules

essential nutrients must be obtained from an animal's diet, they are divided in four classes:

Essential amino acids
Essential fatty acids
Vitamins
Minerals

Amino Acids in an animals diet...

- Meat, eggs, and cheese provide all the essential amino acids and are thus "complete" proteins
- Most plant proteins are incomplete in amino acid composition
- Vegetarians can easily obtain all essential amino acids by eating a varied diet of plant proteins

animals can synthesize about ______ of the amino acids they need from their diet.

half

Essential fatty acids in an animal diet include...

- certain unsaturated fatty acids (i.e., fatty acids with one or more double bonds)
- Animals typically obtain ample amounts of essential fatty acids in their diet

Vitamins

organic molecules required in the diet in very small amounts
Vitamins are grouped into two categories: fat-soluble and water-soluble

________ vitamins are essential for humans

13

Minerals

- Simple inorganic nutrients, usually required in small amounts
- Ingesting large amounts of some minerals can upset homeostatic balance

Malnutrition

failure to obtain adequate nutrition

- Deficiencies in essential nutrients can cause deformities, disease, and death
- In children, protein deficiency may arise when their diet shifts from breast milk to foods containing very little protein

Undernourishment

when a diet does not provide enough chemical energy

An undernourished individual will...

- Use up stored fat and carbohydrates
- Break down its own proteins
- Lose muscle mass
- Suffer protein deficiency of the brain
- Die or suffer irreversible damage

Food processing involves:

ingestion, digestion, absorption, elimination

Digestion

the process of breaking food down into molecules small enough to be absorbed

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

In ________, the process of enzymatic hydrolysis splits bonds in molecules with the addition of water

chemical digestion

Absorption

uptake of small molecules by body cells

Elimination

the passage of undigested material out of the digestive system

intracellular digestion

food particles are engulfed by phagocytosis and liquids by pinocytosis

In intracellular digestion, food particles are engulfed by _________ and liquids by _________.

phagocytosis, pinocytosis

Food vacuoles, containing food, fuse with...

lysosomes containing hydrolytic enzymes

Extracellular digestion

the breakdown of food particles outside of cells, It occurs in compartments that are continuous with the outside of the animal's body.

alimentary canal

Complex animals have a digestive tube with two openings, a mouth and an anus.

In mammals, several accessory glands secrete __________

digestive juices through ducts into the alimentary canal.

Mammalian accessory glands are the...

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

Food processing begins in the _______

oral cavity

Salivary glands

deliver saliva to lubricate food

Saliva contains ________, a viscous mixture of water, salts, cells, and glycoproteins
Saliva also contains ________, which breaks down starch

mucus, amylase

The _______ movements shape food into a ______ and help with swallowing

tongue, bolus

The throat, or ________, is the junction that opens to both the esophagus and the trachea

pharynx

esophagus

connects to the stomach

- Swallowing causes the epiglottis to block entry to the trachea, and the bolus is guided by the larynx, the upper part of the respiratory tract.

Coughing occurs when...

the swallowing reflex fails, and food or liquids reach the windpipe.

stomach

stores food and processes it into a liquid suspension

The stomach secretes ______
The mixture of this and ingested food is called _______

gastric juice, chyme

Gastric juice

- Has a low pH of about 2, which kills bacteria and denatures proteins
- Is made up of hydrochloric acid (HCl) and pepsin, a protease, which breaks peptide bonds to cleave proteins into smaller peptides
- Mucus protects the stomach lining from gastric juice

Cell division adds a new epithelial layer every three days (mitosis) True or false

TRUE

Coordinated contraction and relaxation of stomach muscles...

churn the stomach's contents

Sphincters

- Prevent chyme from entering the esophagus and regulate its entry into the small intestine.

What is Heartburn caused by?

If the sphincter at the top of the stomach allows movement of chyme back to the lower end of the esophagus.

Ulcers are usually caused by_______

bacteria

small intestine

the longest compartment of the alimentary canal, most enzymatic hydrolysis of macromolecules from food occurs here.

duodenum

The first portion of the small intestine
- Here, chyme from the stomach mixes with digestive juices from the pancreas, liver, gallbladder, and the small intestine itself

pancreas

Produces the proteases trypsin and chymotrypsin, which are activated in the lumen of the duodenum.
- Its solution is alkaline and neutralizes the acidic chyme

bile 3 main functions

- Salts facilitate digestion of fats
- Bile is made in the liver and stored in the gallbladder
- Bile also destroys nonfunctional red blood cells

The small intestine has a huge surface area due to _____ and ______ that are exposed to the intestinal lumen.

villi, microvilli

Transport across the epithelial cells are always passive. (True or False)

FALSE
Transport across the epithelial cells can be passive or active, depending on the nutrient

hepatic portal vein

carries nutrient-rich blood from the capillaries of the villi to the liver, then to the heart

liver

regulates nutrient distribution, interconverts many organic molecules, and detoxifies many organic molecules

7 Steps of processing in the large intestine:

1, The alimentary canal ends with the large intestine It includes the colon, caecum, and rectum.
2, The colon leads to the rectum and anus
The cecum aids in the fermentation of plant material and connects where the small and large intestines meet
3, The human cecum has an extension called the appendix, which plays a minor role in immunity
4, The colon completes the recovery of water that began in the small intestine
5, Feces, the wastes of the digestive system, become more solid as they move through the colon
6, Feces are stored in the rectum until they can be eliminated through the anus
7, Two sphincters between the rectum and anus control bowel movements

Dentition

an animal's assortment of teeth, is one example of structural variation reflecting diet

The success of mammals is due in part to their dentition, which is specialized for different diets. (True or false)

True :)

The coexistence of humans and many bacteria involves...

mutualistic symbiosis

Some intestinal bacteria produce vitamins (True or false)

True!

microbiome

the collection of the microorganisms living on the body

Scientists use a DNA sequencing approach based on the __________to study the microbiome

polymerase chain reaction
- There are differences in the microbiome associated with diet, disease, and age

The processes that enable an animal to obtain nutrients are matched to the....

organism's circumstances and need for energy

adipose cells

Where excess energy is stored in fat

The body stores energy-rich molecules that are not needed for metabolism right away (True or false)

True

In humans, energy is stored first in the liver and muscle cells in the _______

polymer glycogen

When fewer calories are taken in than expended, the human body expends _______ first, then _________, and fat.

liver glycogen, muscle glycogen

The hormones ______ regulate the breakdown of glycogen into glucose
The _____ is the site for glucose homeostasis.

insulin and glucagon, liver

A carbohydrate-rich meal raises ______ levels, which triggers the synthesis of glycogen
Low blood sugar causes ______ to stimulate the breakdown of glycogen and release glucose

insulin, glucagon

Insulin acts on...

all body cells to stimulate glucose uptake from the blood. (With the exception of brain cells)

Glucagon and insulin are both produced in the ______

islets of the pancreas,

_______ make glucagon, and ______ make insulin

Alpha cells, beta cells

diabetes mellitus 3 main characteristics

- Caused by a deficiency of insulin or a decreased response to insulin in target tissues
- Cells are unable to take up enough glucose to meet metabolic needs
- The level of glucose in the blood may exceed the capacity of kidneys to reabsorb it.

Type 1 Diabetes

- An autoimmune disorder in which the immune system destroys the beta cells of the pancreas
- It usually appears during childhood
Treatment consists of insulin injections, typically several times per day

Type 2 Diabetes

- non-insulin-dependent diabetes, is characterized by a failure of target cells to respond normally to insulin
- Excess body weight and lack of exercise significantly increase the risk of type 2 diabetes
- It generally appears after age 40, but may develop earlier in younger people who are sedentary

Over nourishment causes...

obesity, which results from excessive intake of food energy with the excess stored as fat
- Obesity contributes to type 2 diabetes, cancer of the colon and breasts, heart attacks, and strokes

Hormones regulate long-term and short-term appetite by affecting a ______ in the brain

"satiety center"

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

What food items are typical of an herbivorous diet?

Nuts, leaves, berries

Animals need two types of organic precursors from their food, __________, to serve as the raw materials for the synthesis of larger organic molecules.

organic carbon and organic nitrogen

A breakfast cereal advertises that it contains essential vitamins and minerals. In this context, the word essential means __________.

that the nutrients must be supplied in the diet and cannot be made in the body

In general, B vitamins function in your body as __________.

coenzymes

The fat-soluble vitamins include __________.

vitamins A, D, E, and K

An insufficient supply of chemical energy in the diet or a shortage of one or more essential nutrients results in what?

Malnutrition

Which of the following statements about nutrition and digestion is true?

During absorption, small molecules such as amino acids and simple sugars are absorbed.

What animal has a gastrovascular cavity with a single opening?

Hydra

What animal uses only intracellular digestion?

Sponge

peristalsis

Rhythmic contraction waves move food along the digestive system's length along the smooth muscle.

How is the stomach lining protected from the strongly acidic pH of its contents?

Mucous cells secrete a protective lubricant into the stomach.

What might make the most effective anti-ulcer medication?

A chemical that kills bacteria in the stomach

Which of the following processes, structures, or conditions are properly matched?

acid chyme backflow; heartburn

The liver and pancreas add their secretions to the partially digested food produced in the stomach, in the __________ of the small intestine.

duodenum

The natural antacid that protects the intestines against stomach acid is produced by the __________.

pancreas

Gallstone surgery sometimes requires that the gallbladder be removed. Patients are then advised to avoid ingesting large amounts of fat because __________.

the gallbladder stores large quantities of bile, which is used to emulsify fats

Where does absorption take place in the small intestine?

Microvilli

The lymphatic vessels in the villi absorb and transport __________.

chylomicrons

Symbiotic bacteria living in our large intestines provide us with __________.

vitamins

What is an adaptation to a carnivorous diet?

Sharp, pointed teeth

How would you expect the digestive system of a hawk to compare with that of a seed-eating sparrow?

The sparrow's digestive system would be longer.

Leptin, an appetite regulator, is produced in __________ and at high levels can lead to __________.

adipose tissue; suppressed appetite