Animal Phys Exam 1

What is animal physiology?

• How animals work

• All levels, from whole animal to molecular level

What are examples of limiting factors?

• Temperature

• Water

• Oxygen

How do small desert animals avoid heat?

Living in burrows that have a more favorable microclimate

How do small mammals avoid extremely cold temperatures?

Living in the subnivean space beneath the snow cover

External Layer of Body

Contacts external environment

Cells

Only in contact with internal environment

The __ environment influences the __ environment that cells and tissues are in contact with

External, internal

The internal environment of animals can be __ to be different from the external environment they are living in

Regulated

Internal conditions can either

• Vary and follow external changes (conformers)

• Remain constant & not follow external changes

Animals are. either __ conformers or __

Physiological, regulators

Physiological conformers

Internal systems follow changes

Regulators

Internal systems oppose changes

Animals that regulate internal physiological parameters do it by using

Homeostatic mechanisms

What do homeostatic mechanisms do?

Maintain internal conditions within set limits using negative feedback loops

Metabolism

• Sum of processes by which animals acquire energy

• Energy channeled into useful functions

• Unused energy dissipated from body

Chemical Energy

Does all forms of physiological work, maintenance, external work, it always generates heat - “totipotent”

Electrical & Mechanical Energy

Only do some forms of physiological work

Heat Energy

Heat is low-grade energy, not usable for physiological work

Metabolic Rate

• Determines how much food is needed; how much food energy animal removes from ecosystem

• A measure of total activity because energy-using processes produce heat

• A measure of rate at which chemical energy is converted into work & heat

• Chemical energy in food converted into chemical energy in body, heat, & work

Energy use per unit of time

C6H12O6 + 6O2 —> 6CO2 + 6H2O + ATP + heat

Units of Heat Energy

Measured in calories or joules

calorie (cal)

One calorie of heat is required to heat one gram of water by one degree Celsius

Kilocalorie (kcal)

1,000 calories = 1 Calorie

One calorie of heat raises…

1 gram of water by 1 degree Celsius

One Calorie (kcal) of heat raises…

1 kg water (= 1 liter) by 1 degree Celsius

Joule (J)

SI unit of energy

Kilojoule (kJ)

1,000 Joules

To convert calories to Joules

1 cal = 4.186 J

Watt (rate)

1 Watt (W) = 1 J/s

Metabolic Rate units for heat production

• kcals/min

• 1 kcal = 4.186 kJ

Use direct calorimetry to measure metabolic rate:

If aquatic animal, measure the difference in water temp. between 2 identical containers, one with an animal and one without

Respiratory Quotient (RQ)

• CO2 produced/O2 consumed

• RQ which fuel used in metabolism

Basal Metabolic Rate (BMR)

Resting metabolic rate that applies to mammals & birds

Standard Metabolic Rate (SMR)

Resting MR that applies to poikilotherms (ectotherms)

Specific Dynamic Action (SDA)

Metabolic rate increase that follows food ingestion

What type of relationship is BMR vs BW?

Allometric

Metabolic Rate vs BW allometric relationship has important

Physiological implications

Respiratory & Circulatory physiology varies allometrically with changes in ___

Body weight

Weight-specific resting metabolic rate of small animals is __ than in large animals

Higher

Number of capillaries & mitochondria in muscle fibers is __ in small species than large species

Higher

The resting heart beat of small animals is __ than that of large animals

Higher

In one week, the meadow vole eats how much?

6x its body weight

In one week, a rhino eats how much?

1/3 its body weight

Although a given area of African grassland has fewer large animals & more small animals, there are fewer small animals than expected, due to their higher food demands from their

High weight-specific BMR

When an animal grows in size, its surface area & volume both increase, but

at different rates

Animals with high body temp. (38°C) __

constantly lose heat to environment

Rate of heat loss proportional to surface area (b = 0.63) because

heat lost across body surface

Small mammals have

high weight- specific SA (& high rate of heat loss)

large mammals have

low weight-specific SA (& low rate of heat loss)

Reason why weight-specific BMR of small mammals greater than that of large mammals

They lose more heat across body surface & this needs to be replaced by increased metabolism to maintain constant internal body temp. of 38°C

Rubner’s Surface Heat Loss theory was developed for __ but does not apply to __

Homeotherms, poikilotherms

Explanation for why the MR/BW relationship has an allometric exponent (slope b) ~0.7

Remains unknown

ATP is the __ of the Cell

Universal Energy Carrier

Cells Make ATP from

Glucose

Lot of free energy released when third phosphate group of ATP removed by hydrolysis

ATP + H2O -> ADP + Pi

ATP __ between cells; ATP __ in cells

• Not transferred

• Not stored

Cells make own ATP in 2 pathways

• Aerobic

• Anaerobic

ATP made

ADP + Pi + energy from food —> ATP

ATP used

ATP —> ADP + Pi + energy usable by cells

Enzyme Cofactors NAD and FAD

‘e- carriers’; cell gets NAD from niacin (vitamin B3), FAD from riboflavin (vit. B2)

Cell makes reduced form of NADH2

NAD+ + 2H —> NADH + H+ (NADH2 makes 2.3 ATP)

Cell makes reduced form of FADH2

FAD+ + 2H —> FADH + H+ (FADH2 makes 1.4 ATP)

Inner membrane folded into crests that project into __

Matrix

__ supports the proteins of the electron-transport chain

Inner membrane

Matrix contains the enzymes that catalyze the breakdown of pyruvic acid & run the __

citric acid cycle

Respiration in cells

GLUCOSE + 602 = 6CO2 + 6H2O + ENERGY

Aerobic catabolism of glucose consists of 4 major sets of reactions

1. Glycolysis

2. Krebs Cycle

3. Electron Transport Chain

4. Oxidative Phosphorylation

Glycolysis - Energy Expenditure & Gain in Glycolysis per mol. of glucose

1. 2 mols. of pyruvic acid made

2. 2 mols. NAD reduced to 2 mols. NADH2

3. 2 mols. ATP used, & 4 Mols. ATP formed; 2 mols. ATP net gained

Glycolysis step 1 - Each glucose molecule (6-Carbon sugar) broken down to

2 mols. of pyruvic acid (3-C molecule)

Glycolysis step 2 - Each glucose molecule reduces

2 molecules of NAD to 2 molecules of NADH2

Glycolysis step 3 - 2 mols ATP used;

4 mols ATP produced per molecule of glucose (net gain of 2 ATPs)

If O2 present (aerobic): Glycolysis proceeds to

Krebs cycle

Pyruvic acid oxidized by enzyme

pyruvate dehydrogenase complex (PDC)

Pyruvic acid (3C) decarboxylated resulting in

2C acetate

Pyruvic Acid (3C) + Coenzyme A —>

Acetyl Coenzyme A (2C)

Krebs Cycle step 1 - Pyruvic Acid (3C) decarboxylated to

Acetyl-CoA (2C)

Krebs Cycle step 2 - Acetyl-CoA (2C) coupled to

Oxaloacetic Acid (4C)

Krebs Cycle step 3 - Cycle undergoes series of

enzymatic steps (C6, C5, C4)

Krebs Cycle step 4 - final step regenerates Oxaloacetic Acid (4C) which

combines with Acetyl-CoA (2C) & makes Citric Acid (6C) and Cycle turns again

Krebs Cycle - Each glucose molecule produces

6 mols of CO2; 8 mols of NADH2; 2 mols of FADH2; 2 mols of ATP

What does the Electron Transport Chain do?

Completes transfer of energy from food bonds in glucose to ATP

ETC - Consists of 4 protein complexes

1. Complex I (NADH dehydrogenase)

2. Complex II (succinate dehydrogenase)

3. Complex III (cytochrome b-c)

4. Complex IV cytochrome oxidase (CO1) (cytochrome a)

5. plus: Ubiquinone (coenzyme Q)

What moves along the electron transport chain?

Movement of H+ & Electrons

Reduced coenzymes __ & __ are fed into the ETC

NADH2 & FADH2

ETC - H2 removed from coenzymes releases

e- & H+ (energy)

Electrons transferred in steps along ETC; ends with

O2

ETC - Protons (H+) pumped against their conc. gradient (active transport) from

matrix into intermembrane space using energy released by e- transport)

ETC & OP - When O2 present in cell

1 mol glucose makes ~30 ATP via Krebs Cycle & ETC

ETC passes electrons in steps to oxygen (final electron acceptor) to produce

Water

ETC pumps H+ to

intermembrane space (creates proton gradient)

Chemiosmosis in Mitochondria

High conc of protons (H+) sets up strong proton diffusion gradient that drives H+ return to matrix through ATP synthase; phosphorylates ADP, makes ATP

ETC & OP - Each molecule of glucose yields

29.8 ATP net (31.8 ATP gross) when glycolysis, Krebs cycle, & ETC work together (1 glucose mol. yields 2 pyruvic acid mols, & these turn the Krebs Cycle 2 times)

Summary of ATP production - step 1

12 pairs of electrons removed from each glucose molecule

Summary of glycolysis

glucose to pyruvic acid: 2 NADH2 (2 x 2.3 = 4.6 ATPs)

Summary of Pyruvic acid to acetyl CoA & Krebs Cycle

8 NADH2 (8 x 2.3 = 18.4 ATPs)

Summary of Krebs Cycle

2 FADH2 (2 x 1.4 = 2.8) making Total of 25.8 ATPs

Summary of ATP production - last step

Plus 4 ATPS produced directly (2 in glycolysis, 2 in Krebs Cycle) = 29.8 ATPs (~30 ATPs)

When O2 absent from cell (anaerobic)

glycolysis only (Krebs Cycle & ETC disabled): 1 mol glucose produces 2 ATPs

Anaerobic catabolism of glucose forms

Pyruvic acid

Anaerobic Respiration - pyruvic acid reduced to either

lactic acid (muscles) or ethanol (yeast)