Intro to Physiology and Homeostasis

Question 1

Define physiology.

Answer 1

Study of how structure and
function of the body work
together to allow behavioral
responses to the environment

Question 2

What are some applications of animal physiology?

Answer 2

Understanding human health and diseases
* Agricultural production of animals for food
* Understanding invasive species
* Understanding environments/habitats and
interrelationships

Question 3

What is the importance of environment with physiology?

Answer 3

Environment is often related to structure.

Question 4

What are the 5 limitations environmental limitations discussed? Which is the most limiting?

Answer 4

1. Temperature*
2. pH
3. Lack of water
4. Radiation
5. Light

Question 5

What are the 3 limitations that affect animal physiology?

Answer 5

Environmental limitations
- Scaling limitations
- Evolutionary limitations

Question 6

What is the biggest challenge for animals living in aquatic environments? Why?

Answer 6

Not having easy access to oxygen. Oxygen is 20x more available in air; extracting from water takes a lot of energy

Question 7

What are 5 conditions animals living in aquatic environments are exposed to?

Answer 7

Wet all the time
Less light
More dense, more viscous
Oxygen is hard to extract
Abundant suspended nutrients

Question 8

What factors are animals in terrestrial environments expose to?

Answer 8

Dry all the time (dehydration)
More light (easier to regulate temp)
Less dense, less viscous
Oxygen easier to extract
No suspended nutrients (need to actively seek out food)

Question 9

What conditions make Earth optimal for life?

Answer 9

Carbon is very abundant and works optimally under the present planetary conditions
Water is the most abundant liquid molecule (though organisms did have to adapt to some drawbacks)
Light is plenitful
Averages temperatures allow for versatile organic covalent compounds

Question 10

What happens when an object doubles in size?

Answer 10

• Its surface area (SA) increases by a factor of 4
• Its volume (V) increases by a factor of 8
• Its surface area to volume ratio decreases

Question 11

Why does scaling matter?

Answer 11

The surface of organism is involved in exchange of material
with the environment while the volume is responsible for
the processing and use of these materials.

Question 12

What is the difference in thermoregulation between large and small animals?

Answer 12

Small animals –
SA:V large, problems when
undercooling
Large animals –
SA:V small, problems when
overheating

Question 13

How can evolution limit an animal’s physiology?

Answer 13

Diversity of adaptations to the environment is limited by ancestry

Question 14

What is homeostasis?

Answer 14

The ability of organisms to maintain steady conditions internally despite environmental conditions. i.e., maintaining pH, chemical concentration, temperature, etc.

Question 15

What is meant by homeostasis being dynamic?

Answer 15

The organs and organ systems within animals are constantly adjusting to any internal or external stages to maintain this steady state. It’s not a matter of this state just staying stable, but the body being able to regulate conditions as needed to maintain it.

Question 16

What is the mechanism that maintains homeostasis?

Answer 16

Negative feedback

Question 17

What is negative feedback?

Answer 17

A mechanism that aims to reduce a deviation from normal conditions in order to get things back within normal, livable ranges.

Question 18

What are the basic components of a negative feedback system? What do they do?

Answer 18

A sensor/receptor that monitors a physiological value
The control centre, which compares values measured by the sensor to the normal range.
An effector that induces the change in order to reverse the situtation and return to the set point.

Question 19

Can set point ever be altered?

Answer 19

set point may be altered in some instances. For example, during an infection, which results in a fever. This makes internal conditions unfavourable for bacterial

Question 20

What is set point?

Answer 20

A set point is the value at which homeostasis aims to maintain.

Question 21

What is thermoregulation?

Answer 21

The process that maintains homeostasis of temperature

Question 22

Explain the difference between vasodilation and vasoconstriction in thermoregulation.

Answer 22

Vasodilation brings more blood and heat to the surface of the body, initiating radiation and evaporative heat loss, which helps cool the body. Vasoconstriction bring blood toward vital organs, conserving heat.

Question 23

What is positive feedback?

Answer 23

A deviation from the normal range
results in more change, and the system
moves farther away from the normal
range.

Question 24

What processes does positive feedback occur in?

Answer 24

Positive feedback occurs infrequently in biological systems but
is involved in important processes:
* the production of the action potential
* childbirth
* clot production

Question 25

Explain the loop of positive feedback in giving birth.

Answer 25

Head of baby pushes against cervix.
Nerve impulses from cervix transmitted to brain
Brain stimulates pituitary gland to secrete oxytocin
Oxy carried in bloodstream to uterus
Oxy stimulates uterine contractions and pushed baby towards cervix
Continues untilbaby is delivered and there is no longer and pressure on the cervix

Question 26

Explain the difference between conformers and regulators.

Answer 26

a) Conformers internal environment varies with the external environment
b) Regulators maintain internal stability even as external conditions change

Question 27

What are the limits of conformers and regulators?

Answer 27

Regulators cannot control internal conditions under extreme conditions.
Even conformers have limitations. They cannot endlessly conform no matter the environment.

Question 28

Explain the difference between ectotherms and endotherms.

Answer 28

Ectotherms: Animals that do not have internal control of their body temperature. The body
temperature is generally similar to the temperature of the environment.
Endotherm : An animal that maintains a constant body temperature in the face of environmental
changes These animals are able to maintain a level of activity because they generate internal heat
that keeps their cellular processes operating optimally even when the environment is cold.

Question 29

What are some adaptations of elephants as endotherms?

Answer 29

Endotherm mechanisms…
Elephants:
- skin is several sizes too big as more skin = more heat loss
- mud collects in folds, holding moisture close to the skin; evaporates and cools over time
- ears radiate a lot of heat; blood vessels open and allow cooling of the thin skin; also flap their ears to aid in cooling of blood, which travels to rest of the body and cools it.

Question 30

What are some adaptations of penguins as endotherms?

Answer 30

• huddle together, taking turns in the middle
• densely-packed, overlapping, waterproof feathers
• feathers can trap a layer of insulating air against body
• small, fat-lined feet
• blood warms body before reaching the feet

Question 31

What are some benefits of being a regulator?

Answer 31

Pros:
- Can inhabit broader range of niches because their internal conditions can adjust to different environments
- More metabollically active
- Can get much larger than conformers

Question 32

What are some drawbacks of being a regulator?

Answer 32

:
- require more energy in order to maintain internal conditions
- require constant food supply in order to meet energy needs
- have altered social behaviours as their internal regulations are not enough in extreme environments to survive alone

Question 33

What are some benefits of being a conformer?

Answer 33

• Less energy required overall
• Can slow down metabolic activity when required as they don’t spend energy regulating internal temperatures
• Can survive in solitude

Question 34

What are some drawbacks of being a conformer?

Answer 34

limited in size