any phys

before fall midterm

define membrane potential

the difference in charge between the inside and outside of the cell

what is the resting membrane potential of a typical neuron

-70 mV

define action potential

brief electrical signal characterized by a rapid rise and fall in the membrane potential

are voltage gated sodium channels open or closed at rest?

closed

what part of the hypothalamus is the thermostat of the body?

the preoptic area (POA)

what are the 4 steps that lead to an action potential?

1. resting membrane potential

2. rising phase

3. falling phase

4. recovery

why does a lower core body temperature lead to a longer life span?

decreased body temperature means decreased metabolic rate (energy savings)

or

lower metabolic demands = slower aging

how do ectotherms maintain a healthy temperature?

behavioral thermoregulation

how could an ectotherm bring its core body temp down if it was too high?

• move to a shady location

• pant

• reduce contact with hot surfaces (stilting)

how could an ectotherm bring its core body temp up if it was too low?

• move to a sunny spot

• increase contact with hot surfaces

define acute changes

• Short-term changes in the physiology of individual animals, exhibited within minutes of the environment changing.

• Acute changes are reversible 

define chronic changes

• Long-term changes in the physiology of individual animals, exhibited within days, weeks, or months of the environment changing

• Chronic changes are reversible

define evolutionary changes

Changes that occur by alteration of gene frequencies in populations, exhibited over the course of multiple generations

what are the three steps for any animal to regulate body temperature?

• Sense

• Integrate

• Respond

define threshold potential

the energy level that must be met in order to trigger an action potential

at what temps is the difference in metabolic rate between ectotherms and endotherms the greatest?

at the lower temperature because ectotherms don’t have the ability to regulate internally so their bodies slow and in turn, so do their metabolic rates. endotherms can maintain their temps internally, but that takes energy so their metabolic rates remain elavated.

what are the three parts of the core concept of information flow?

• information stored in DNA is expressed as RNA and proteins

• organisms have special mechanisms for sensing internal and external change and signaling to coordinate responses

• if one step is interrupted, future steps are too

why would increasing positive ions in the neuron cause an action potential sometimes but not always?

Possibility #1: If the change in membrane potential is not enough to reach threshold

Possibility #2: If voltage gated Na+ channels were not functioning

Possibility #3: If membrane potential is farther away from threshold

define basal metabolic rate

an animal’s energy consumption while resting and fasting

what are the three parts of the core concept of evolution?

• mutations to proteins can affect anatomy and function of all levels

• most organisms have traits that increase fitness for a particular environment

• physiological systems have limits that lead to tradeoffs that affect fitness

define metabolic rate

an animal’s rate of energy consumption; the rate at which it converts food into heat and movement

give two more synonyms for chronic changes

acclimation or phenotypic plasticity

define phenotypic plasticity

the ability of an individual animal to express multiple traits/phenotypes

what are the two parts of the core concept of structure function?

• physical properties affect the function of biological structures

• specialization in one structure may inhibit the performance of another