Ch 33 & 34: Nutrition, Circulation & Gas Exchange in Animals

Question 1

Describe the 3 categories of animals based on their diet and provide examples for each

Answer 1

Herbivores - An animal that mainly eats plants or algae (cattle, caterpillars)

Carnivores - An animal that mainly eats other animals (lions, tigers, hawks)

Omnivores - An animal that regularly eats animals as well as plants (humans, cockroaches, crows)

Question 2

Define the terms:nutrition, ingestion, digestion, absorption, elimination, metabolism

Answer 2

• Nutrition: Food is taken in (eating & ingestion), taken apart (digestion), and taken up (absorption), and what cannot be digested is rejected (elimination)
• Ingestion is the process of taking food in mouth and swallowing it
• Digestion is the process of breaking down food into molecules small enough to absorb
  
  • Mechanical digestion (ex: chewing)
  • Chemical digestion (uses enzymatic hydrolysis, enzymes + water break bonds in molecules)
• Absorption is uptake of nutrients into the circulatory system
• Elimination is the passage of undigested material out of the alimentary canal / digestive system, and out of the body
• Metabolism is the totality of an organism’s chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism.

Question 3

Briefly explain enzymatic hydrolysis and generalize the process

Answer 3

Chemical digestion by enzymes reverses this process by breaking bonds through the addition of water. This splitting process is catalyzed by enzymes and is called enzymatic hydrolysis.

Question 4

Compare the feeding & digestion strategies found in animals

Answer 4

• Intracellular Digestion - Food vacuoles—cellular organelles in which hydrolytic enzymes break down food—are the simplest digestive compartments.
• Extracellular Digestion - Animals with relatively simple body plans typically have a digestive compartment with a single opening. This pouch, called a gastrovascular cavity, functions in digestion as well as in the distribution of nutrients throughout the body (hence the vascular part of the term). Animals with complex body plans have a digestive tube with two openings: a mouth and an anus (Alimentary Canal).

Question 5

Explain the advantages of compartmentalization in nutrition

Answer 5

Food generally moves along the alimentary canal in a single direction, encountering a series of specialized compartments that carry out stepwise digestion and nutrient absorption. An animal with an alimentary canal can ingest food while earlier meals are still being digested, a feat that is likely to be difficult or inefficient for an animal with a gastrovascular cavity.

Question 6

Contrast the vertebrate alimentary canals in relation with their diets

Answer 6

In general, herbivores and omnivores have longer alimentary canals relative to their body size than do carnivores. Plant matter is more difficult to digest than meat because it contains cell walls. A longer digestive tract furnishes more time for digestion and more surface area for nutrient absorption.

Question 7

Contrast the vertebrate dentition in relation with their diets

Answer 7

• Carnivores: generally have large, pointed incisors and canines that can be used to kill prey and rip or cut away pieces of flesh. The jagged premolars and molars crush and shred food.
• Herbivores: usually have premolars and molars with broad, ridged surfaces that grind tough plant material. The incisors and canines are generally modified for biting off pieces of vegetation. In some herbivores, canines are absent
• Omnivores: Humans are adapted to eating both plants and meat. Adults have 32 teeth. From front to back along either side of the mouth are four bladelike incisors for biting, a pair of pointed canines for tearing, four premolars for grinding, and six molars for crushing

Question 8

Explain the different aspects of metabolism in animals

Answer 8

• Breaking down (lysis) -> catabolism
  
  • The macromolecules ingested are broken down by the digestive system into nutrients monomers: glucose, fatty acids & amino acids, which will allow to generate ATP
• Building things (genesis) -> anabolism
  
  • Smaller compounds, monomers are combined to make a larger compound, such as proteins, nucleic acids, carbohydrates, lipids, & all other macromolecules -> biosynthesis
• Energy can be stored for later use
  
  • Animals convert nutrients into forms that can be stored (ex: fats in adipocytes)

Question 9

List the functions of circulatory systems

Answer 9

• Transport and Exchanges
  
  • Nutrients
  • Oxygen
  • Carbon dioxide & metabolic wastes
  • Regulatory molecules: Hormones
• Thermoregulation
• Protection
  
  • Defense against pathogens

Question 10

Compare direct versus indirect exchange systems

Answer 10

• Direct exchange system: A simple body plan that places many or all cells in direct contact with the environment; Each cell can thus exchange materials directly with the surrounding medium.
• Indirect exchange system: Animals that lack a simple body plan display an alternative adaptation for efficient exchange: a circulatory system.

Question 11

Contrast the structure of openand closed circulatory systems & identify the functional advantages of each

Answer 11

Open: Hemolymph bathes tissues and organs directly and there is no distinction between the circulating fluid and the interstitial fluid

Advantage: The lower hydrostatic pressures typically associated with open circulatory systems allow them to use less energy than closed systems;

Closed: Blood is confined to vessels and is kept separate from interstitial fluid

Advantages: Closed circulatory systems are particularly well suited to regulating the distribution of blood to different organs; Blood pressure that is high enough to enable the effective delivery of O2 and nutrients in larger and more active animals.

Question 12

Compare hemolymph with blood

Answer 12

Blood is used in closed circulatory systems of vertebrate species while hemolymph is found in open circulatory systems of invertebrates. Hemolymph and blood vary greatly in their composition and function. While blood’s main purpose is to transport oxygen around the body, hemolymph combines the functions of both blood and lymph fluid, transporting not only oxygen but other molecules and nutrients as well.

Question 13

Annotate the 3 types of vertebrate circulatory systems

Answer 13

Single Circulation: Blood travels through the body and returns to its starting point in a single circuit (loop); heart that consists of two chambers: an atrium and a ventricle; sharks, rays, fish

Double Circulation, 3 and 4 Chambered Heart: Amphibians, reptiles, and mammals have double circulation; Having both pumps within a heart simplifies coordination of the pumping cycle; Oxygen-poor and oxygen-rich blood is pumped separately from the right and left sides of the heart

Question 14

Define pulmonary and systemic circulation

Answer 14

Pulmonary - the system of transportation that shunts de-oxygenated blood from the heart to the lungs to be re-saturated with oxygen

Systemic - It carries oxygen and nutrients to the cells and picks up carbon dioxide and waste products.

Question 15

Describe the advantages of double circulation (with separation of pulmonary and systemic circulation)

Answer 15

It is important because it allows oxygenated blood to be separated from deoxygenated blood, whichincreases the efficiency of oxygen transport and energy production in the body.

Question 16

Explain what is meant by partial pressure

Answer 16

The pressure exerted by a particular gas in a mixture of gases

Question 17

Describe and contrast the structure of respiratory systems in fish, insects, birds, and mammals

Answer 17

Gills in Aquatic Animals: Gills are outfoldings of the body surface that are suspended in the water. Most gill-bearing animals either move their gills through the water or move water over their gills. The water has a higher PO2 than the incoming blood, and O2 transfer takes place.

Tracheal Systems in Insects: A network of air tubes that branch throughout the body; The largest tubes, called tracheae, open to the outside. At the tips of the finest branches, a moist epithelial lining enables gas exchange by diffusion. Because the tracheal system brings air within a very short distance of virtually every body cell in an insect, the efficient exchange of O2 and CO2 does not require participation of the animal’s open circulatory system.

Lungs in birds and mammals: Because the respiratory surface of a lung is not in direct contact with all other parts of the body, the gap must be bridged by the circulatory system, which transports gases between the lungs and the rest of the body.

Question 18

Describe countercurrent exchange in fish gills and explain why it enhances gas exchange

Answer 18

Countercurrent exchange: the exchange of a substance or heat between two fluids flowing in opposite directions.

In a fish gill, the two fluids are blood and water. Because blood flows in the direction opposite to that of water passing over the gills, at each point in its travel blood is less saturated with O2 than the water it meets. As blood enters a gill capillary, it encounters water that is completing its passage through the gill. Depleted of much of its dissolved O2, this water nevertheless has a higher PO2 than the incoming blood, and O2 transfer takes place.

Question 19

Describe the tracheal system in insects

Answer 19

Tracheal Systems in Insects: A network of air tubes that branch throughout the body; The largest tubes, called tracheae, open to the outside. At the tips of the finest branches, a moist epithelial lining enables gas exchange by diffusion. Because the tracheal system brings air within a very short distance of virtually every body cell in an insect, the efficient exchange of O2 and CO2 does not require participation of the animal’s open circulatory system.

Question 20

Describehow birds breath (lungs with airs and 2 cycles)

Answer 20

• Birds have posterior & anterior air sacs that function as bellows that keep air flowing through the lungs
• Air passes through the lungs of birds in one direction only
• Passage of air through the entire system—lungs and air sacs —requires two cycles in inhalation and exhalation

Question 21

Explainhow the lungs are ventilated in vertebrates and what structures are involved

Answer 21

• Mammals ventilate their lungs by negative pressure breathing, air is inspired (IN) and expired (OUT) due to the creating of a pressure gradient between the air inside the lung versus outside of the lungs.
• Inspiration is possible due to inside the lungs as compared to the outside
• Lung volume increases / decreases as the inspiration muscles (rib cage muscles) and diaphragm contract / relaxes

Question 22

Comparepositive-pressure VS negative pressure breathing

Answer 22

Positive-pressure: Air is forced into the lungs

Negative-pressure: Air is pulled into the lungs

Question 23

Explain how diseases such as emphysema can impact lung function

Answer 23

Alveoli are weakened and their walls can become damaged; Leads to shortness of breath and less oxygen entering the blood