In Person Exam I

Physiology

the study of the functions of living things, focusing on the mechanisms of action

Top Down level of Organization

examines higher levels of organization, and indoors functions for lower levels of organization

Bottom-Up level of organizaion

examines lower levels of organization and infers functions for higher levels of organization

The advent of genome projects has led to _________ approach

bottom-up

In Vivo

takes place inside an organism

In Vitro

performing a given experiment in a controlled environment outside of a living organism

In Situ

examines a phenomenon exactly in place where it occurs

In Silico

performed on computer on via computer simulation

Genomics

study of whole sets of genes, done by sequencing

Transcriptomics

study of full set of RNAs, done by microarrays sequencing

Proteomics

study of all proteins encoded by a genome, done by mass spectrometry

Metabolomics

study of metabolites, done by mass spectrometry and NMR

Dynamic Steady State

changes that occur are minimized by compensatory physiological responses

Homeostatic Control System

functionally Interconnected network of body components that operate to maintain a given factor in the internal environment relatively constant around an optimal level

In a Homeostatic Control System Must be Able to:

• Detect

• Integrate

• Make adjustments

________ is the main mechanism for homeostatis

Negative Feedback is the main regulatory

Regulators

use internal mechanisms to maintain a relatively constant state

Conformers

internal state varies with that of the environment

Acute Changes

occur within minutes to hours of exposure → reversible

Chronic Changes

occur after prolonged exposure → reversible

Acclimatization

refers to the physiological/biochemical/anatomical chronic changes in organisms in the natural environment

Phenotypic Plasticity

a single phenotype generates more than one phenotype depending on environmental conditions

Evolutionary Changes

occur after exposure of multiple generations to a new environment → not reversible

Isozymes

forms of enzymes within one species

Interspecific Enzyme Homologs

forms of enzymes between species

Metabolism

all chemical reactions occurring in an organism

Catabolism

reactions that break down complex, energy-rich molecules into simpler molecules → releases energy that can be captured in ATP

Anabolism

reactions that require energy and transforms simple compounds into more complex ones

__% of energy may be captured in ATP, _% is released as heat

40, 60

Uses of Energy

• Biosynthesis

• Maintenance

• Generation of External Work

Metabolic Rate

overall use of chemical energy by an animal per unit time

Basal Metabolic Rate (BMR)

minimum energy expenditure required to maintain basic physiological functions

→ used by Endotherms

Measuring Basal Metabolic Rate

measured under standardized conditions in the thermal neutral zone

Thermoneutral Zone

the range of ambient temperatures where an animal's body maintains a stable internal temperature without changing its metabolic rate or using evaporative cooling like sweating

Standard Metabolic Rate (SMR)

Varies with environmental temperature

→ used by Ectotherms

Resting Metabolic Rate (RMR)

Energy required to maintain basic biological functions while resting

RMR is measured under ___ restrictive conditions that BMR/SMR

less

Direct Calorimetry

measures heat production released by an organisms over a given period of time

Indirect Calorimetry

measures oxygen consumption and carbon dioxide production

Indirect Calorimetry How to Calculate Metabolism Rate

O2 consumed/min * (the cal produced by L of CO2 produced)

Respiratory Quotient

(molecules CO2 eliminated)/(molecules of O2 consumed) OR V_CO2/V_O2

Avogadro’s Law

for gas (at constant temperaure an pressure) the volume is directly proportional to the number of molecules in the gas

→ V_CO2 = constant * molecules of CO2

Specific Dynamic Actions (SDA)

the increase in metabolic rate following a meal, reflects the energy cost of:

• ingestion

• digestion

• absorption and transport of nutrients

• post-absorptive processing

Typical Increase in Metabolic rate after meal in:

1. Mammals

2. Fish

3. Pythons

1. 30% RMR

2. 2-8 SMR

3. 30-40 SMR

Scaling Relationship Equations

Y =aX^b

if b =/= 1 in the Scaling Relationship Y = aX^b

it is a non-linear Relationship with allometric scaling

Allomertric Relationship Equation

MR = aW^b

• MR = metabolic rate

• W = animal weight/mass

• a,b = constants, with a depending on animal and b=0.7

Equation for Body Size and Metabolic Rate

MR=aW^b OR log(MR) = log a + b (logW)

• MR = metabolic rate

• W = animal weight

• b = slope of log-log plot

• log a = y-intercept of log-log plot

Mass Specific Metabolic Rate

MR/W

• metabolic Rate

• Weight

MR/W = aW^b/W = aW^(b-1)

• a

• b

is 1 kcal/min = 1 Cal/min

True

1 cal = ?

4.184 J

Issues with Direct Calorimetry

complex procedure, stressed animals, expensive calorimeter

Allometry

the study of how specific body parts, biological traits, or metabolic rates change in proportion to an organism's overall body size

Conduction

transfer of heat through physical contact. Heat moves from warmer region to cooler region

Convection

transfer of heat by movement of a fluid (air/water). Moving fluid carries heat away from the body

Radiation

transfer of heat by electromagnetic radiation

Evaporation

heat loss when liquid water changes to water vapour → the energy required comes from the body as heat

Homeotherms

maintain a relatively stable body temperature despite changes in environmental temperature. Can remain active in wide range of environmental temperatures

Poikilotherms

body temperature varies with environmental temperature. Become less active at low temperatures

Endotherms

generate metabolic heat to help regulate body temperature (tb)

Ectotherms

rely primarily on environmental heat sources to regulate body temperature (ex: fish)

Ectotherms can regulate body temperature to some extent through ______

behavioural thermoregulation (lizards basking in sun)

Heterotherms

animals that can vary their thermoregulatory strategy of body temperature across space or time

Regional Heterotherms

different parts of the body have different temperatures

Temporal Heterotherms

body temperature varies over time. Animals can temporarily reduce metabolic heat production and allow body temperature to decrease (hibernation)

Stenothermal

can tolerate a narrow range of environmental temperatures

Eurythermal

can tolerate a wide range of environmental temperatures

Why do animals regulate body temperature?

metabolic reactions and enzymes are optimized for a particular temperature range → optimizes physiological performance

Thermal optimum

temperature where performance is maximal

Pejus Range

a zone of environmental temperature where an animal can still survive, but its physical performance and energy levels slowly drop

Q₁₀ Definition

temperature coefficient, the change in metabolic rate caused by a 10C change in body temperature

Q₁₀ Equation

R_T/R(_T-10) where,

R_T = MR at T degrees

R_T-10 = MR at T-10 degrees

Acute Temperate Change between Environment and MR

log MR = log a + n * TB

Compensation

long - term tendency to return to original level

Biological Significance of Compensaiotn

• reduces acute effects

• allows animal to maintain some level of activity

Compensation results from…

changes in enzyme concentrations, and shifts in relative isoforms

Chronic-Response Line

how MR varies if animals are allowed to acclimate at each temp

Cold-adapted enzyme varients

maintain efficient substrate binding and catalytic activity

Antifreeze Proteins (AFPs)

bind to ice crystals and prevent or limit their growth

Cryoprotectants in freeze-tolerant species

• accumulate molecules such as glucose and glycerol

• reduce cellular damage caused by freezing

• stabilize proteins and cell membranes

• limit tissue damage

Thermal Neutral Zone (TNZ)

range of temperature which MR is independent of Ta

(MR = metabolic rate, Ta =

Lower critical temperature

the lowest T in the thermal neutral zone

Upper critical termperature

the highest T in the thermal neutral zone

Basal Metabolic Rate

metabolic rate when resting and fasting in the thermal neutral zone

Outside Thermal Neutral Zone, ___ is insufficient to maintain __, causing an increase in the ____

BMR, Tb, MR

Endotherm’s Temperature regulation strategies

1. behavioural strategies

2. increase metabolic production

3. minimize loss and gain of heat (insulation, circulatory mechanisms)

Shivering Thermogenesis

using shivering; synchronized contraction and relaxation of skeletal muscle units at random. This used ATP and produced heat

Non-Shivering Thermogenesis

in specialized highly vascular brown adipose tissue (BAT)

piloerection

rising of hair → traps layer of air → serves as insulation

Why is Brown Adipose Tissue Brown?

caused by high blood supply and high mitochondria content

Steps of Oxidative Phosphorylation

1. The proton electrochemical gradient produced by electron transport: energy store

2. back-diffusion of protons via ATP sytnth

Counter-Current Heat Exchange

arrangement of arteries and veins in extremities that allows heat in warm arterial blood to be transferred to cooler venous blood returning from extremeties

→arteries are parallel to veins

→flow in opposite directions

Vasoconstriction and Dilation

alteration of blood flow to body surface depending on temperature:

• Cold: constriction of superficial (cutaneous) arterioles that reduces blood flow to extremities to minimize heat loss

• Heat: dilation which increases blood flow to skin to enhance heat loss

Evaporative Cooling

heat is used to evaporate water. Effective cooling but results in water loss:

• sweating, panting, spread saliva or urine over body

Gular Fluttering

rapid movement of the throat/floor of the mouth in birds for cooling

Temperature Detection and Thermoregulation Pathway

1. Thermal input via peripheral and visceral thermoreceptors

2. Signal modulation in the spinal cord and brain stem

3. signal is sent to the pre optic region of the anterior hypothalamus

4. stimulation of thermoregulatory responses

Torpor

short-term decrease in body temperature and MR. reduces energy expenditure in small small mammals and birds

Hibernation

prolonged periods of torpor, typically associated with winter. Lasting weeks to months where MR and Tb decrease. Tb is regulated at a much lower level and approaches environmental temperature

Bears do not undergo a _________ as small hibernators. Could be better described as _______

profound decrease in Tb, shallow hibernation/winter sleep

Estivation

prolonged reduction in metabolic activity during hot/dry conditions. Helps to conserve water and energy, and is common in ectotherms